AERODROME DESIGN MANUAL PART 5 ELECTRICAL SYSTEMS FIRST EDITION - 98 3 Approved by the Secretary General and publi shed under his authority INTERNATIONAL CIVIL -4VI-ATION ORGA NIZATION
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AERODROME
DESIGN
MANUAL
PART 5
ELECTRICAL SYSTEMS
FIRST EDITION- 983
Approved by the Secretary General
and published under his authority
INTERNATIONAL CIVIL -4VI-ATION ORGA NIZA TION
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AerodromeDesign
Manual(Doc 9157-AN/901)
Part 5
Electrical Systems
First Edition - 983
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AMENDMENTS
Amendments are announced in the supplelnenfs to the Catalogue of ICAOPublications; the Catalogue and its supplements are available on the ICA O w ebsite
at www.icao.int. The space below is provided to keep a record o f such amendments.
%%ECO;taD F AMENDMENTS AND CORRIGENDA
CORRIGENDA
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P ro pe r d e s ig n , i n s t a l l a t i o n a nd m ai nt en an ce of e l e c t r i c a l s y s te m s f o r n av i
g a t i o n a i d s , b ot h v i s u a l and n o n v i s u a l , a r e p r e re q u i s i t e s f o r t h e s a f e t y , r e g u l a r i t y ,
a nd e f f i c i e n c y o f c i v i l a v i a t i o n . To t h i s e n d , t h i s m an ual p r o v i d e s g u i da n c e o n t h e
d e s i g n an d i n s t a l l a t i o n of e l e c t r i c a l s ys te ms f o r a er od ro me l i g h t i n g a nd r a d i o n av ig a-
t i o n a i d s .
The e l e c t r i c a l s ys te ms f o r ae rod ro me l i g h t i n g an d r a d i o n a v i g a t i o n a i d s
i n c l u d e f e a t u r e s w hi ch a r e n o t u s u a l ly i nv ol ve d i n o t h e r e l e c t r i c a l i n s t a l l a t i o n s . T h
m an ual t h e r e f o r e d i s c u s s e s n o t o n l y t h e g e n e r a l f e a t u r e s o f e l e c t r i c a l p r a c t i c e s a nd
i n s t a l l a t i o n s b ut a l s o t h o s e f e a t u r e s w hi ch a r e of s p e c i a l s i g n i f i c a n c e f o r ae ro dr om e
i n s t a l l a t i o n s . It i s a ss um ed t h a t r e a d e r s o f t h e ma nu al w i l l b e f a m i l i a r w i t h e le c -
t r i c a l c i r c u i t s a nd g e n e r a l d e s i g n c o n c e p ts , b u t may n o t be k no wl ed ge ab le o f c e r t a i n
f e a t u r e s o f ae ro dr om e i n s t a l l a t i o n s w hic h a r e l e s s f r e q u e n t l y e n c o u n te r ed i n o t h e r
i n s t a l l a t i o n s . It i s i m po r ta nt t o n o t e t h a t t h e m a t e r i a l p r e s en t e d i n t h i s m anual i s
i n te n d ed t o complement n a t i o n a l s a f e t y c od es r e l a t e d t o e l e c t r i c a l i n s t a l l a t i o n s .
The manual d o es n o t d i s c u s s e l e c t r i c a l s y st em s f o r b u i l d i n g s l o c a t e d on a n
a i r p o r t o t h e r t h a n t h e e f f e c t o f s uc h b u i l d i n gs o n t o t a l power r e q ui r em e n ts f o r p r im ar
a nd s e co n d a r y p ow er s u p p l i e s . S i m i l a r l y , t h e m an ua l d o e s n o t d e a l w i t h t h e m a i n te n a nc
o f e l e c t r i c a l sy st em s. F or g ui da nc e on t h i s l a t t e r i s s u e t h e r ea d e r i s a d vi se d t o r e f et o t h e A i r p o r t S e r v i c e s M anu al, (Doc 9 1 3 7 ) , P a r t 9 , A i r p o r t M a i n t e n a n c e P r a c t i c e s .
F u t u r e e d i t i o n s of t h i s man ual w i l l b e im pr ov ed o n t h e b a s i s o f e x p e r i e n c e
ga ine d and o f comments and sug ges t io ns rece ived f rom us e r s of t h i s manual . Reade rs o f
t h i s m an ua l a r e i n v i t e d t o g i v e t h e i r v i e w s, comments an d su g g e s t i o n s t o t h e S e c r e t a r y
Genera l o f ICAO .
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Chap te r 1. I n t r o d u c t i o n .................................................... -1
1.1 Purpose ............................................................ -1
1.2 O r g a n i z a t i o n o f t h e m an ua l ............................................-1............................................hapter 2. E l e c t r i c i t y S u pp l ie s 5-2
2'1 Sources of power ......................... ~ ~ P O O O O O O O O i O O O
2.1.1 Gene ra l ..................................................... -2........................................1.2 Primary power sources 5-2
2.1.3 Secondary power s ou rc es ..................................... -2...........................1.4 D i s t r i b u t i o n o f i n t e r m e d i a t e power 5-3
2.2 Power t r a n s f e r c h a r a c t e r i s t i c s ...................................... -32.2.1 T r a n s f e r ( s w i t c h - o v e r ) t im e r e q u i r e m e n t s .................... -3
2.2.2 Cont inuous power sources .................................... -3
2.2.3 Methods o f t r a n s f e r ......................................... -5
2.3Secondary power equipment
..........................................-72.3.1 Components .................................................. -7
2.3.2 Eng ine -gene ra to r se t s .......................................-92.3.3 Power t r a n s f e r s w i t c h i n g .................................... -10...............................3.4 U n i n t e r r u p t i b l e p ower s u p p l i e s 5-10..............................3.5 Spe c ia l seconda ry power de v ic e s 5-11
2.4 V a u lt s an d s h e l t e r s f o r e l e c t r i c a l eq uip me nt ....................... -11.....................................................4.1 She l t e r s 5-11
2.4.2 L a c a t i o n ....................................................-13...........................................4.3 S p e c i a l p r o v i s i o n s 5-13
2.5 Di s t r i bu t i on of power .............................................. -14.....................................................s5sl Genera l 5-14
2.5.2 P ri ma ry p ower f e e d e r c i r c u i t s ............................... -15
2.5.3A bo ve -g ro un d ( o v e r h e a d ) p r i m ar y d i s t r i b u t i o n s y s t e m s
.......=5--152.5.4 L i n e - v o l t a g e r e g u l a t o r s ....................... ( r ( r ( r ( r ( r ( r ( r O s D D D..................................................5.5 Power l i n e s 5-16
2.5.6 Conductors .................................................. -16...................................................5.7 I n s u l a t o r s 5-17
2.5.8 Lacknuts .................................................... -18.................................................5.9 Transfo rmers 5-18
2.5.10 C a p a c i t o r s .................................................. -19.................................5.11 C i r c u i t i n t e r r u p t i o n d e v ic e s 5-19
2.5.12 L i g h t n i n g p r o t e c t i o n ........................................-20...................................................5.13 C l e a r a n c e s 5-20
2.5.14 Grounding ................................................... 5-20.............................5.15 U nd er gr ou nd d i s t r i b u t i o n s ys t e m s 5-21
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Chapter 3. E l e c t r i c a l C i r c u i t s f o r Aerodrom e L i g h t i n g a nd R a d io
Navigat ion Aids ........................................................... -23
.......................................ypes of e l e c t r i c a l c i r c u i t s 5-23
3.1.1 E l e c t r i c a l c h a r a c t e r i s t i c s .................................. -23
..............................................1.2 S e ri e s c i r c u i t s 5-23
3. 1.3 P a r a l l e l c i r c u i t s ........................................... -24
..........1.4 Comparison of s e r i e s an d p a r a l l e l l i g h t i n g c i r c u i t s 5-25
............................e r i e s c i r c u i t r y f o r aero dro me l i g h t i n g 5-25
.....................................2.1 F a c t o r s t o be c o n s i d e r e d 5-25
P a r a l l e l ( m u l ti p l e ) c i r c u i t r y ...................................... -41
3.3.1 Use of p a r a l l e l ( m u l t i p l e ) c i r c u i t r y i n ae ro dr om e l i g h t i n g .. -41..............................on t ro l o f ae rodrome l ig h t in g sys tems 5-42
............................................4.1 C o nt r ol c i r c u i t r y 5-42
3.4.2 C o n t r o l p a n e l s .............................................. -433.4.3 Use of re lays ............................................... -443.4.4 I n t e r c o n n e c t i o n o f c o n t r o l s ................................. -45
3.4.5 A u t o m a t i c c o n t r o l s .......................................... -45
3.4.6 Radio remote con t ro l s ....................................... -46..............................................................amps 5-46
3.5.1 C h a r a c t e r i s t i c s of i n c a n d e s c e n t la mp s ....................... -46
...................5.2 C h a r a c t e r i s t i c s o f g a s e o u s d i s c h a r g e lam ps 5-48
Methods of o b t a i n i n g i n t e g r i t y a nd r e l i a b i l i t y f o r a er od ro me
l i g h t i n g ......................................................... -493.6.1 D e f i n i t i o n o f t e rm s ......................................... -49
3.6.2 Summary o f means o f improv ing e l e c t r i c a l i n t e g r i t y
and r e l i a b i l i t y ........................................... -50M f n i t o r in g o f a er od ro me l i g h t i n g c i r c u i t s .......................... 5-51
3.7.1 Methods of monitoring . ~ ~ ~ ~ ~ . ~ ~ e ~ e ~ ~ ~ ~ . ~ ~ . ~ ~ ~ ~ e 6 6 6 6 6 L-51t - *
3.7.2 Des ign of moni to r ing d ev i ces................................
- 3 "
3.7.3 Clas se s of moni to rs .......................................a.-51....................................7.4 M on it or o v e r r i d e c o n t r o l s 5-52
E l e c t r i c a l c i r c u i t s f o r r a d i o na vi ga t i on a i d s ..................a.e.-523.8.1 Types of r a d i o n a v i g a t i o n a i d s .............................. -52
3.8.2 E l e c t r i c a l c h a r a c t e r i s t i c s ....................C*......e a O O 0 5 - 5 23.8.3 C on tr ol c i r c u i t s f o r r a d i o n a v ig a ti o n a i d s .................. -53
3.8.4 R e l i a b i l i t y a nd i n t e g r i t y of r a d i o n a vi g a t i on a i d s .......... -54
3.8.5 M o ni to r in g of r a d i o n a v i g a t i o n a i d s ......................... -54
A c ce p ta n ce t e s t i n g o f aerodrom e e l e c t r i c a l c i r c u i t s ................ -54
3.9.1 A p p l i c a t i o n ................................................. -543.9.2 Guaran tee pe r iod ............................................ -55
........................................9.3 I n s p e c t i o n p r o c e d u r e s 5-55
3.9.4 E l e c t r i c a l t e s t of s e r i e s - c i r c u i t e qu ip men t
.................-57
3.9.5 E l e c t r i c a l t e s t s of o t h e r ca b l e s ............................ -59
3.9.6 E l e c t r i c a l t e s t s of r e g u l at o r s .............................. 5-60
........................................9.7 T r ou b l es h o ot i n g t e s t s 5-61
3.9.8 E l e c t r i c a l t e s t s of o t h e r e quip men t .........*...........*...-62............................................9.9 Tes t s o f moni to rs 5-62
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1.1 PURPOSE
1.1.1 To e n s u r e t h e r e g u l a r i t y a nd s a f e t y of a v i a t i o n , i t i s n e c e s s a r y t h a t a e r o -
drome l i g h t i n g a nd r a d i o n a v i g a t i o n a l a i d s ha ve hi g h i n t e g r i t y a nd r e l i a b i l i t y . It i s
c o n s id e r ed t h a t t h e p r o b a b i l i t y o f f a i l u r e o f w e l l d es i gn e d a nd m ai n ta i ne d l i g h t i n g a n d
r a d i o a i d s a t a c r i t i c a l moment i s ex t reme ly low ,
1.1.2 The f o l l o w i n g m a t e r i a l i s i n t e n d e d as a g u i d e t o t h e r ecommended e l e c t r i c a
e n g i n e e r i n g p r a c t i c e s f o r d e s i g n a nd i n s t a l l a t i o n of new sy st em s a nd t h e m o d i f ic a t i o n o
e x i s t i n g sy s te m s of a e ro dr om e f i x e d l i g h t i n g an d of d i s t r i b u t i o n o f pow er t o r a d i o
n a v i g a t io n a i d s . It does n o t im ply t h a t e x i s t i n g i n s t a l l a t i o n s , i f d i f f e r e n t , a r e wron
and shou ld be changed au t om a t i ca l ly . It d o e s mean t h a t some of t h e e a r l i e r d e s i g n s
a d o pt e d a r e n o t recommended f o r r e p e t i t i o n s i n c e t h e y h av e b ee n s u p e r s e d e d by l a t e r
t h i n k i n g . B ecause of t h e d i f f e r e n c e s i n e n g i n e e r in g s t y l e an d e qu ip me nt i n d i f f e r e n t
c o u n t r i e s , t h i s m a t e r i al e s t a b l i s h e s o n ly b a s i c d e si g n p ri n c i p l es .It i s
n o t i n t e n d e dt o i l l u s t r a t e d e t a i l e d d es i g n o r p a r t i c u l a r pi e c e s o f e qu ip men t o r s y st em s un iq ue t o an
o n e S t a t e .
1.1.3 The e l e c t r i c a l s y st em s f o r a er od ro me v i s u a l a i d s a n d n a v i g a t i o n s y s te m s
r e q u i r e good q u a l i t y i n s t a l l a t i o n s a nd c o n s i de r a t i o n f o r f e a t u r e s wh ich a r e no t u s u a l l y
i n vo lv e d i n o t h e r e l e c t r i c a l i n s t a l l a t i o n s . T hi s manual d i s c u s s e s t h e g e n e r a l f e a t u r e s
o f e l e c t r i c a l p r a c t i c e s an d i n s t a l l a t i o n s w i t h e mp has is on t h o s e f e a t u r e s wh ich a r e l e s
commonly i n v o l v e d o r h av e s p e c i a l s i g n i f i c a n c e f o r a er od ro m e o p e r a t i o n s . I t i s assumed
t h a t t h o s e u s i n g t h i s m an ual w i l l be f a m i l i a r w i t h e l e c t r i c a l c i r c u i t s a nd g e n er a l
p r a c t i c e s b u t may n o t b e k n ow l ed g ea b le of c e r t a i n f e a t u r e s o f ae ro dr om e i n s t a l l a t i o n s
w hi ch a r e l e s s f r e q u e n t l y e n c ou n t er e d i n o t h e r e l e c t r i c a l s y st e ms . Some o f t h e s e
f e a t u r e s a r e t h a t most e l e c t r i c a l c i r c u i t s a r e i n s t a l l e d un der gr oun d, s e r i e s c i r c u i t s
a r e u se d f o r m ost l i g h t i n g s ys te ms , h i g h e r r e l i a b i l i t y i s r e q u i r e d o f t h e i n p u t p ower
s o u r c e s , a nd r a p i d , a u t o m a t i c t r a n s f e r t o s ec o nd a ry power i n c a s e of power f a i l u r e s .
Each aerodrome i s unique , and i t s e l e c t r i c a l i n s t a l l a t i o n s h ou ld be d e s ig n ed t o p r o vi de
economic a l ly power and co n tr o l which i s s a f e , r e l i a b l e , a nd e a s i l y m ai nt ai ne d.
1.2 ORGANIZATION OF THE :NNUAL
1 .2.1 T h i s m an ual p r o v i d e s i n f o r m a t i o n o n t h e E l e c t r i c i t y S u p p l i e s i n C h a pt e r 2,
E l e c t r i c a l C i r c u i t s f o r A erodrom e L i g h t i n g a nd N av i g a ti o n Ai ds i n C h a pt e r 3, Undergroun
E l e c t r i c a l S ys tem s i n C h ap te r 4 , and Cab le s f o r Unde rg round Se rv ice a t Aerodromes i n
Chap te r 5.
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2 .1 SOURCES OF POWER
2 . 1 . 1 Gene ra l
2 .1 .1 .1 The p r imary sou rc e s o f power f o r a erod romes shou ld be de te rmined be fo re t h e
d e s i g n s of t h e aer odr om e l i g h t i n g i n s t a l l a t i o n s and t h e r a d i o n a v i g a t i o n a i d s a re
i n i t i a t e d . The e l e c t r i c a l power f o r t h e s e i n s t a l l a t i o n s i s u s u a l l y o n ly a s m a l l p a r t o f
t h e e l e c t r i c a l pow er u s e d by t h e a er od ro me . W he th er t h e v i s u a l an d r a d i o n a v i g a t i o n
a i d s b e i n g i n s t a l l e d a r e f o r a n ew ae ro dr om e o r f o r m o d er n i za t io n a nd e x p a n s io n of a n
e x i s t i n g a er od ro me , t h e s o u r c e s o f power s h o u l d b e a n a ly z ed f o r a v a i l a b i l i t y , c a p a c i t y ,
r e l i a b i l i t y , p r a c t i c a l i t y f o r t h e p ro po se d i n s t a l l a t i o n , and f o r f u t u r e e xp a ns i on . T h is
a n a l y s i s s h o u l d i n c l u d e b o t h t h e p r i m a ry p ower s o u r c e a nd t h e s e c o n d a ry pow er s o u r c e
required by Annex 1 0 , Volume I , 2 .9 and Annex 1 4 , 8.1 f o r u s e i n c a s e s of f a i l u r e o r
ma l fu nc t ion o f th e p r imary power sou rce .
Pr imary power sources
2 . 1 . 2 . 1 The p r imary sou r ce s o f power f o r most a e rod romes a r e f ee de rs f rom a w i d e l y
i n t e r co n n e c te d e l e c t r i c i t y ne tw or k o u t s i d e t h e a e ro dr om e, u s u a l l y f ro m e i t h e r a commer-
c i a l o r a p u b l i c m ains s u pp ly . In some ca se s t h e power may come f rom a l o c a l g en e r a t i ng
p l a n t o r f ro m a l i m i t e d d i s t r i b u t i o n s ys te m. Two independ ent incoming power s ou rc es a r e
d e s i r a b l e f o r m a jo r a er o dr o me s , i n s t e a d o f a s i n g l e pr i m ar y power s o u r c e . T hey s h o u l d
come fr o m w i d e l y s e p a r a t e d s e c t i o n s o f t h e e l e c t r i c i t y ne t wo r k b ey on d t h e a e ro d ro m e w i t h
e ac h s up p ly in g s e p ar a t e c i r c u i t s t h a t would p r ov id e i n t e g r i t y o f f a c i l i t i e s if one
f a i l e d . P r e f e r a b l y , t h e s e s o u r c e s w i l l h ave s e p a r a t e f e e d e r s f ro m s e p a r a t e s u b s t a t i o n s
an d w i l l a l s o be f ro m d i f f e r e n t g e n e r a t o r s . O t he r s u p p l y a r r a n g em e n t s may b e u s e d
depend ing on th e security, r e l i a b i l i t y , s t a t i s t i c s , o r economics a p p l ic a b l e t o a
p a r t i c u l a r situation,
2 , 1 . 2 . 2 This power i s u s u a l l y s u p p l i e d a t h i g h e r v o l t a g e ( o v er 5 0 0 0 v o l t s ) t o t h e
aerodrome main power substa t ion .
2 . 1 . 3 Secondary power sources
2 .1 .3 .1 Most a e ro d ro m es w i t h a e ro dr om e l i g h t i n g a n d r a d i o n a v i g a t i o n a i d s s h o u l d b e
p r o v i d e d w i t h s e c on d a ry e l e c t r i c a l power f o r t h e a i d s r e q u i r e d a s a minimum f o r o p e ra -
t i o n s . The c i r c u i t s an d f a c i l i t i e s t o be pr o vi d ed w i th s ec on d ar y power v a r y w i t h t h e
m os t c r i t i c a l c l a s s o r c a te g o ry of f l i g h t o p e r a ti o n s . The ae ro dro me f a c i l i t i e s f o r
which a seco ndary power supply i s recommended a r e i nd ic a t ed i n Annex 1 4 , C h a p t e r 8 f o r
v i s u a l a i d s an d i n Annex 1 0 , Volume I , P a r t I , Chap te r 2 f o r r a d i o n a v ig a t i o n a i d s .
Those f a c i l i t i e s f o r w hi ch s e c on d ar y p ower i s r e q u i r e d s h o u ld be a r r an g e d t oa u t o m a t i c a l l y c o n ne c t t o t h e s e c o nd a r y power s u p p l y on f a i l u r e of t h e p r im a r y s o u r c e
power.
2.1.3 .2 So urc es of se co nd ar y power. As recommended i n Annex 1 4 , Chap te r 8, s o a r c e s
of secondary power may be independent p ub l i c power so ur ces o r s tand-by power u n i t s .
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2.1.3.3 For ae rod romes w i th t hep r i ma r y s u pp d ep e nd e nt e l e c t r i c a l
t r an smi ss i on power l i n e s may be u sed t o p rov i de seconda ry power . These independen t
power s o u r c e s a r e n o t u s u a l l y c o n ne ct e d t o t h e a er od ro me l i g h t i n g an d r a d i o n a v i g a t i o n
a i d s l o a d s b u t c an be a u t o m a t i c a l l y c on ne ct ed t o t h e s e l o a d s i n c a s e of f a i l u r e of t h ep r imary power sou rce . These independen t power sou r ce s may be i n a r e se rv e s t a t u s on ly
o r may b e s u p p ly i ng e l e c t r i c a l p ower t o o t h e r f a c i l i t i e s on t h e a er od ro me . An
i n d ep e n de n t s o u r ce s u p p l yi n g power t o o t h e r f a c i l i t i e s s h o u ld ha ve a d e q u a t e c a p a c i t y t o
p r o v i d e t h e p ower f o r t h e more e s s e n t i a l a er od ro me l i g h t i n g an d r a d i o n a v i g a t i o n a i d s i n
a d d i t i o n t o t h e u s u a l l o a d o r s w i t c h i n g a r ra n ge m en ts s h o ul d be p r o v i de d t o d i s c o n n e c t
f rom i t s u s u a l l o a d a s i t i s c on ne ct ed t o t h e l i g h t i n g a nd r a d i o a i d s l o ad . The
improvement i n in t eg r i t y o f o pe r a t i ons p rov ided by independen t power sou rc e s depends on
t h e s e p a r a t i o n a nd i n de p e nd e n ce of t h i s s o u r c e f ro m t h e p r i m ar y s o u r c e . I f t h e two
s o u r c e s come f ro m i n t e r c o n n e c t e d d i s t r i b u t i o n n et w or k s, a f a i l u r e i n t h e n et w or k may
c au s e b o th s o u r c es t o f a i l . An ind epe nde nt power sou rc e may be used as a seconda ry
power so u rc e i f i t h a s t h e c a p a c i t y t o s u pp ly i t s own l o a d p l u s t h e a e r o dr o me l i g h t i n g
a nd r a d i o a i d s load and i s s o s e p a r a t e d t h a t a n y s i n g l e c au s e o f power f a i l u r e of t h e
p r i m a r y s o u r c ew i l l
n o t i n t e r f e r e w i t h power f r om t h e o t h e r s o u r c e .Unless
t h ei n d e p e n d e n t s o u r c e Is c o m pl e te l y i s o l a t e d f r om t h e p r i ma r y s o u r c e a nd w i l l n o t b e
o v e r l o a de d u po n f a i l u r e o f t h e p ri m a r y s o u r c e , l o c a l s e co n d ar y pow er s h o u l d b e pr o v id e d
f o r t h e v i s u a l an d r a d i o n a v i g a t i o n a i d s e s s e n t i a l t o t h e o p e r a t i o n s of t h e a er od ro me .
2 .1 .3 .4 Independent l o c a l power sou rce . Some aerodromes may have t u rb o - a l t e r na t o r
m ot or u n i t s whic h a r e us e d t o s up p ly power t o n o n - c r i t i c al f a c i l i t i e s . T he se l o c a l
power s o u r c e s may b e u s e d a s t h e s e c o n d a r y s o u r c e of power f o r c r i t i c a l a e ro d ro m e l i g h t -
i n g and r a d i o n a v i g a t i o n a l a i d s . I f t h e p ri ma ry power f a i l s , t h e c r i t i c a l l i g h t i n g and
r a d i o a i d s a r e t r a n s f e r r e d a u t o m a t i c a l l y t o t h e l o c a l power s o ur c e . I f t h e l o c a l power
s o u r c e h a s a d e qu a t e c a p a c i t y , t h e l i g h t i n g a nd r a d i o a i d s l o a d may be i n a d d i t i o n t o t h e
u s u a l l o a d . I f t h e c a p a c i t y o f t h e l o c a l power s o u r c e i s l i m i t e d , t h e l o c a l power
s o u r c e may ne ed t o d i s c o n n e c t some of t h e n o n - c r i t i c a l l o a d b e f o r e c o n n e c t i n g t o t h e
c r i t i c a l l i g h t i n g and r a d i o a i d s l oa d.
2.1.3.5 . Another a rrangement i s t o s u p p l y t h e pow er
f o r t h e ae ro dr om e l i g h t i n g a nd r a d i o n a v i g a t i o n a l a i d s f r om t u r b o - a l t e r n a t o r m ot or u n i t s-w hi ch may a l s o be s u p p l y in g power t o o t h e r f a c i l i t i e s . I f t h i s s o u r c e o f power f a i l s ,
t h e c r i t i c a l l i g h t i n g and r a d i o a i d s l o a d may be t r a n s f e r r e d a u t o m a t i c a l l y t o t h e
p r imary power sou rc e f o r t he aerodrome .
2.1.3.6 Stand-by power so ur ce s. Secondary power so ur ce s may be en gi ne -g en er at or
s e t s , o r t u r b i n e g e n e r a t o r s f r o m w hi ch e l e c t r i c a l power c an be o b t a i n e d a n d w hi ch ca n be
a u t o m a t i c a l l y c on ne ct ed t o t h e f a c i l i t i e s r e q u i r i n g s e co nd ar y p ower. The maximum lo a d
which can be connec ted shou l d be w i th in th e ca pa c i t y o f th e st and-by u n i t s . S tand -by
u n i t s w i t h c a p a c i t i e s r a n g i n g f ro m 5 0 t o more t h a n 1 0 00 k i l o v o lt - a m p e r e s a r e u s e d a s
seconda ry power sou r ce s fo r a i rp o r t s . The seconda ry power sou rc e shou ld be capab l e o f
supp ly ing power f o r a t i me pe r i od th a t exceeds th e maximum t ime needed t o r e s t o re powerf rom th e p r imary sou rce . E n gi ne - ge n er a to r s e t s a r e o f t e n e x p ec t ed t o o p e r a t e f o r 24 t o
7 2 h o u r s w i t h o u t r e f u e l l i n g . O th er s e c on d a ry power s o u r c e s , u s u a l l y f o r s m a l l l o a d s ,
may be b a t t e r y u n i t s , f u e l c e l l s , e t c .
2.1.4.1 T1e v o l t a g e f r om t h e p r i ma r y pow er s o u r c e i s u s u a l l y r e d u c ed a t t h e a e r o -
drome s u b s t a t i o a t o a n i n t e r m e d t a t e v o l t a g e ( 2 000 t o 5 500 v o l t s ) f o r d i s t r i b u t i o n
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5-4 A e r o d r o l l l e D e s i g n Manual
Table 2-1. ry Pawer Supply AidsdRBdioAlds
( b m X 14 and &X 10)
P-
- WO ids
C l a s sl icat ion
V i s u a l aids requiring ai
F r r % rt i n e time
Noll-in% trurnent Visual approach slope idicatorsa
W edgeRLmway threshold
e d
Obstaclea
No qm ci si on Approach Lighting sy st wVisual approach slope indicatorsa
m g em y hreshold
b a y nd
Obstaclea
Precision approach
category I
Approach lighting systan
- ~~RLmwq threshold
Kurway ad
Essential taxiway
Obstaclea
Prec ision approach Approach li gh ti ng sys tan
ca tep ry II -Y &S
Runway th re ib ldRumay e rd
Ihlmq oentre line
Runwrny mchdown zone
Stop bars at taxi-holding pcxsitions
Esserltial taxiway including stop bars
other than those at taxl-holdiq
p i t ons
Obs ta cl ea
Precision approach (%me as category I1 excepl- all
ca te rp ry I11 stop bars - I second)
15 seconds
15 seconds
15 seconds15 seconds
15 secarads
L5 seconds
15 seconds
15 seconds15 seconds
l5 &S
15 sec&
15 secorads
1 second
15 s e d s
1 s e d1 second
l &cord
l sfxotki
1 secorad
15 seconds
15 seconds
a. %ppLif?d w i t h s e a m e r when tlleir operatim is essential to tk safety
m
m
MDBD/F facility
IIS locallzer
ILS glide pathIIS middle marker
ILS outer nrucker
PAR
IIS locallzer
ILS glide path
m I n n s ~ ~ l i l l h
ILs middlem outer llm-ka
of f 1igt-s operations.
15 seconds
l5 seconds
15 seconds15 seconds
10 seconds
10 secords
10 seconds
10 secords
10 seconds
0 s e d
0 seconds
1 second1 second
10 seconds
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wi th in th e aerodrome. This power i s u s u a l l y d i s t r i b u t e d by a " p a r a l l e l " s y s te m t o t h e
v a r i o u s t r a ns f or m e r s t a t i o n s f o r f u r t h e r step-down o f v o l t a g e t o w t c h t h e i n p u t v o l ta g
o f t h e e q ui p me n t. Two i n d ep e n de n t i n co m in g e l e c t r i c a l s u p p l i e s t a k e n f ro m w i d e l y
s e p a r a t e d s e c t i o n s o f t h e e l e c t r i c i t y ne t wo r k be yo nd t h e a er od ro m e a r e r ecommended.
W it hi n t h e a er od ro me , r e l i a b i l i t y i n t h e s u pp ly of power t o t h e i n d i v i d u a l s t a t i o n s c a nbe improved by using a c l o s e d r i n g h i g h v o l t a g e i n p u t c i r c u i t w i t h b a l a nc e d v o l t a g e
p r o t e c t i o n o n t h e d i s t r i b u t i o n t r a n s f o r m er s o r by u s i n g a d o u bl e l o o p s y st e m f ro m
i n d ep e n de n t p r i m a ry s o u r c e s o p e r a t i n g a s o pe n r i n g s f e e d i n g two t r a n s f o r m e r s a t e a c h
s t a t i o n . T hi s l a t t e r s ys te m i s i l l u s t r a t e d i n F i g ur e 2-1. I f a c e n t r a l i z e d m o n i to r i ng
s y st e m of t h e l o op s w it c h es a t e a ch s t a t i o n a nd of f a u l t c u r r e n t s l i k e l y t o o cc ur i n
e a ch s e c t i o n a r e u se d p r a c t i c a l l y c om pl et e e l i m i n a t i o n o f p ower f a i l u r e s t o t h e
t r a n s f o r m e r s t a t i o n s c an b e a ch i ev e d. S i mp le r a r ra n ge m en t s p r o v i d i n g l e s s e r r e l i a b i l i t y
may b e u s ed a t s m a l l e r a i r p o r t s .
2.2 POWER TRANSFER CHARACTERISTIC S
2 .2 .1 T ra ns f e r ( swi tch -ove r ) t ime requ i remen ts
2.2.1.1 When t h e p r im a ry power s u p pl y t o t h e more c r i t i c a l v i s u a l a i d s , f a c i l i t i e s ,
a nd r a d i o n a v i g a t i o n a i d s f a i l s , t h e l o a d must b e t r a n s f e r r e d t o t h e s e c o n d a r y power
sou rce . The secondary power sou rce must be s t a r t e d a nd s pe e d a nd v o l t a g e s t a b i l i z e d
b e f o r e t h e l o a d i s t r a n s f e r r e d .
2.2.1.2 The t r a n s f e r , o r s w i t c h - o v e r , t i m e s p e r m i t t e d d ep en d o n t h e m os t c r i t i c a l
i n s t r u m e n t c l a s s i f i c a t i o n o f t h e a e ro d ro m es o p e r a t i o n . Annex 14 , C h a p t e r 8, and Annex
10, Volume I , P a r t I , Attachment C l i s t t h e m aximum p e r m i s s i b l e t r a n s f e r t i m e s f o r t h e
c om po ne nt s of a er od ro m e l i g h t i n g s y s t em s a n d r a d i o a i d s a s s o c i a t e d w i t h n o n - i ns t r um e n t ,
n o n - p r e c i s i o n , a nd p r e c i s i o n a p p r o a ch runw ay c a t e g o r i e s I , I T , an d I I I ; (See Table
2-1. >
Continuous power sources
2.2.2.1 C e r t a i n t y p e s o f l am ps c an n ot b e r e s t a r t e d f o r s e v e r a l m i n ut e s i f t h e r e i s a
break i n t h e cu r r en t th rough th e lamp of more than a few te n t hs o f a s econd . Some types
of r a d i o n a v i g a t i o n a n d co mp ut er d e v i c e s a l l o w n o i n t e r r u p t i o n o f p ow er, I t i s neces-
s a r y t o p r o v i d e a n u n i n t e r r u p t i b l e o r n e a r c o n t i n u o u s s o u r c e o f power when t h e p r i m ar y
power s o u r c e f a i l s t o c a t e r t o s u c h e q ui p me n t. Some d e v i c e s , s u c h a s some c om p ut er s ,
a r e c a p a b l e of a cc om mo da ti ng o n l y v e r y l i m i t e d f l u c t u a t i o n s of f r e q u e n c y o r v o l t a g e a n d
r e q u i r e a t r u l y u n i n t e r r u p t i b l e power su p p ly .
2.2.3 Methods of t r a n s f e r
2 .2 .3 .1 The f o l l o w i n g m et ho ds a r e s u g g e s te d a s p o s s i b l e ways t o r e s t o r e t h e power
s u p p l y w i t h i n t h e s p e c i f i e d maximum t r a n s f e r t i m e s . It i s a d v an t a ge o u s t o g r o u p l o a d s
w i t h s i m i l a r l i m i t i n g t r a n s f e r t im e s s o t h a t t he y may be c o n t r o l l e d a t t h e t r a n sf o r me r
s u p pl y o r a t t h e f e e d e r d i s t r i b u t i o n co n n ec t i on s f r om t h e same s e c on d a ry s o u r c e .
2 ~ i n u t e r a n s f e r t i m . m - e r e a 2 - m in u t e t r a n s f e r t i m e i s p e r m i s s i b l e ,I
l o c a l g a s o l i n e o r d i e s e l e n gi n e- g en er a to r o r g a s tu r b in e -g e n er a t or s e t s
w i t h a u t o m a ti c o r r em ot e s t a r t i n g an d s w i t c h i n g a r e s a t i s f a c t o r y . I n
t h i s 2--m inute p e r i o d t h e e n g i n e o r t u r b i n e c a n b e s t a r t e d a nd t h e speed
and v o l t a g e r e g u l a t i o a ca n b e s t a b i l i z e d .
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o . i g u ~ e2-1, Example of a doub le - loop open-r ing i n t e r -me d i a t e vo l t a g ed i s t r i b u t i o x network
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Pa r t 5.- E le c t r i c a l Sys tems 5-7
2 . 3 .
t h e
majo
b) 15-second t ra n s fe r t ime. Where a 15-second t r a n s fe r t i m e i s r e q u i r e d ,
s t a nd b y d i e s e l a nd g a s o l i n e e n g in e -g e ne ra t or s e t s w i t h r a p i d - s t a r t
c a p a b i l i t y and f a s t - a c t i n g a u t om a t ic s w i t c h i n g o r a n in d ep e nd e nt s o u r c e
w i t h a u t o m a t i c t r a n s f e r s w i t c h i n g c an be used.
c ) 10-second t ra n s fe r t ime. Where a 10-second t r a n s fe r t i m e i s r e q u i r e d ,
s ec o nd a ry power u n i t s w i t h s u i t a b l e s t a r t i n g and s w i tc h -o v er c a p a b i l i t y
can be used.
d) One-second t ra n sf e r t ime. Where a one second swi tch -ov er t ime i sr e qu i r e d , one of t he f o l l ow i ng two m et hods a r e u s ua l l y u s e d f o r t h i s
ra pi d t r a n s f e r of power. One method i s t o s t a r t t h e sta nd -b y d i e s e l
e ng i ne o r ga s t u r b i ne - ge ne r a t o r s e t a s s oon a s t h e RVR i s of the ord er
of 600 m an d o p er a t e t h e more c r i t i c a l l i g h t i n g a nd r a d i o a i d s f ro m t h i
g e n e r a t o r s e t w i th a u t o m a t i c t r a n s f e r t o t h e p r i m a r y power s o u rc e i n
c a s e t he s e conda ry power f a i l s . The c r i t i c a l l oa d power s houl d c on t i nu
t o be fu rn is he d by t he secondary power s ou rce u n t i l an RVR of 800 m i s
reached on a f i rm tre nd of improvements. The second method i s t oa u t om a t i c a l l y s w it c h- ove r t o a s a t i s f a c t o r y i ndepe nden t power s upp l y .
e ) Near z e r o t r a n s f e r ti m e . Very f a s t - a c t i n g ( s w i t c h i ng i n 0 .3 se cond o r
l e s s ) a u t o m a t i c t r a n s f e r d e v i c e s which c a n s w i t c h t h e l o a d f ro m t h e
o p e r a t i n g s ta nd -b y g e n e r a t o r t o t h e pr im a ry s o u r c e a r e r e q u i r e d f o r
l i g h t s u s i ng some t ype s of d i s c ha r ge l am ps i n o r de r t o m a i n t a i n t he
d isch arge . Another method of ob ta in i ng a near - ze ro t r a n s fe r t ime i s t o
us e an i n e r t i a f lyw he e l - d ri ve n ge ne r a t o r wh ic h i s c a pa b l e of m a i n t a i n i n
th e power supply dur ing th e s ta r t -u p of th e secondary power source .
f ) Zero t r a n s f e r ti me . Fo r t h os e f a c i l i t i e s r e q u i r i n g u n i n t e r r u p t i b l e
power and a c c e p t i ng on l y l i m i t e d va r i a t i o ns of vo l t a ge o r f r e que nc y ,
b a t te r y- d ri v e n s t a t i c i n v e r t e r ( s ) o r g e n e r a t o r ( s ) ( s e e F i g u r e 2-2) maybe used . A l though th e secondary power t r an s f e r should us ua l l y be
a cc om pl is he d i n o n l y s e v e r a l s e co n ds , t h e b a t t e r y s e t ( s ) s h ou l d be
c a pa b l e of ope r a t i ng t he f a c i l i t i e s f o r a minimum of 15 m i nu te s w i t hou t
r echarg ing .
2 .3 SECONDARY POWER EQUIPMENT
Component S
1 .1 S ec onda ry e l e c t r i c a l power s hou l d be of s uc h qu a l i t y t h a t it w i l l pr ov i de
r e l i a b i l i t y , a v a i l a b i l i t y , and v o l t a g e s and f r e q u en c i e s n ee de d by t h e f a c i l i t y . Th
r i te ms of secondary power equipment commonly used f o r aerodrome l i g h t i n g and r a d i o
n a v i g a t i o n a i d s a r e en g i n e- g e ne r at o r s e t s , p ow e r- tr an s fe r s w i t c h i n g d e v i c e s , b a t t e r i e s ,
an d b a t t e r y c h a r g e r s t o f u r n i s h power f o r s t a r c i n g t h e e n g i n e g e n e r a t o r s , and v a u l t s o r
s h e l t e r s f o r t h i s e qu ip me nt . L es s o f t e n u s ed , u s u a l l y f o r s p e c i a l f a c i l i t i e s , a r e
un in te r r up t i b l e power (UPS) sys tems , s tandby ba t tery-power sys te ms , s o l a r o r wind
g e n e r a t o r s w i t h b a t t e r y s y st em s , i n de p en d en t g e n e r a t i n g d e v i c e s s u ch a s t h e s m e l e c t r l c ,
nuc l e a r , o r f u e l c e l l s . The s ec ondar y power equi pm en t s houl d be l oc a t e d a s c l o s e a s i s
p r a c t i c a l t o t h e i np u t of t h e f a e i l i t h e a s er ve d.
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--
UPS MODULE
IIIIlII
STATIC
P S UTPUT TO mITICA L BUS
*UPS ( U n i n t e r r u p t i b l e Power Supp ly)
-.r l g u r e 2-2, Ty p i c a l non redundan t uninterruptibfe power s u pp l y
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2 . 3 , 2 . 1 The ba s i c seconda ry power eng ine - gene r a to r s e t co ns i s t s o f a p r ime move r, a
g e n e r at o r o r a l t e r n a t o r , a s t a r t i n g de v ic e , s t a r t i n g c o n t r o l s , and a f u e l t a n k o r
s u p p l y . E n gi ne - ge n er at o r s e t s f o r s e co n da r y power u n i t s a r e u s u a l l y i n 1 00 t o
500 k i lovo l t - ampe re s c a pa c i t i e s b u t may range f rom 50 t o 1 000 k i lovo l t - ampe re s i n
c a p a c i t y .a ) Prime movers. The pr ime movers f o r most secon dary power u n i t s a r e
g a s o l i n e , d i e s e l , o r g a s en g i ne s o r t u r b i n e s , t h e c h o i ce b e i n g b as ed on
c o s t an d a v a i l a b i l i t y of f u e l s . T hes e p ri me movers a r e u s u a l l y
a v a i l a b l e i n s t a n d a r d i ze d s i z e s w i t h a d e qu at e power t o h a n d l e t h e
k i l o v o l t- a m p e r e r a t i n g of t h e g e n e r a t o r . The p r im e m ov er s f o r m os t
m aj or ae ro dr om es a r e r a p i d - s t a r t t y p e s w hi ch c an s t a r t a u t o m a t i c a l l y ,
s t a b i l i z e t h e s p e e d , a n d be c o n ne ct e d t o t h e l o a d w i t h i n 1 0 s e c on d s .
b ) G e n er a t or s . The g e n e r a t o r , u s u a l l y a n a l t e r n a t o r , i s m e c h a n i c a l l y
c o u pl e d t o t h e p r im e mover an d p r o v i d e s s e c o n d a r y e l e c t r i c a l pow er a t
t h e f r e qu e n cy , v o l t a g e , a n d power r a t i n g of t h e u n i t . T he se g e n e r a t o r smay b e e i t h e r s i n g l e p h a se o r t h r e e p ha se . They shou ld have h igh
e f f i c i e n c y i n c o n v e rt i n g m ec ha ni ca l e ne rg y t o e l e c t r i c a l e n e r g y.
c ) S t a r t i n g d e v i c e s . Most s e c on d a ry pow er e n g i n e - g e n e r a t o r s e t s u s e
b a t t e r y pa ck s t o s t o r e e ne rg y f o r s t a r t i n g . B eca us e o f t h e i n f r e q u e n t
u s e , s h o r t o p e r a t i n g p e r i o d s , h i g h s t a r t i n g c u r r e n t d em and s, a nd c o s t ,
l ea d -a ci d t y p e b a t t e r i e s a r e u se d most f r e q u e n t l y f o r s t a r t i n g t h e s e
u n i t s . The b a t t e r y pa ck ( o f t e n a s e t of b a t t e r i e s c on n ec te d i n s e r i e s
a n d / o r p a r a l l e l ) must b e c ap a b le of p r o v i d i n g t h e v o l t a g e a n d c u r r e n t
n eed ed t o s t a r t t h e e ng i n e w i t h i n t h e r e q u i r e d t im e l i m i t s a n d u n d e r t h e
m os t s e v e r e c o n d i t i o n s ( u s u a l l y a l ow t e m p e r a t u r e of - 7 °C ) a t which the
secondary power unl t i s e x p ec t ed t o o p e r a t e . A b a t t e r y c h a r g er w i t h
ove r - cu r re n t and ove r-charge c on t r o l i s p e r ma n e nt l y c o n n e c t ed t o t h ee l c t r i c a l power t o m a in t a in t h e s t o r e d e ne rg y i n t h e b a t t e r i e s . The
b a t t e r y p ac k s h o u ld b e w e l l v e n t i l a t e d t o p r e v e n t a c c u m u l a t i on of
h y dr o ge n g a s a nd s h o u l d be p r o t e c t e d f r o m a r c s , s p a r k s , o r f l a m e s wh i ch
cou ld cause an exp los io n o f any accumula ted ga s . Nickel-cadmium
b a t t e r i e s may be us e d w he re s p e c i a l c o n d i t i o n s w ar r a n t t h e i r h i g h
i n i t i a l c o s t . F l yw h ee l s, p n eu m at ic - pr es s ur e v e s s e l s , o t h e r -t h a n - b at t e r y
s t o re d - en e rg y d e vi c es a r e us ed i n f r e q u e n t l y f o r e n g in e s t a r t i n g be ca us e
o f u n r e l i a b i l i t y o r c o s t .
d ) S t a r t i n g c o n t r o l s . The c o n t r o l s f o r t h e e n g in e - ge n er a t or s e t a r e
u s u a l l y a u to m a ti c s t a r t w i t h t h e s e n s o r f o r p ri ma ry power f a i l u r e a s
p a r t o f t h e t r a n f e r s w i t c h in g d e v i c e . M anual o r re m ot e c o n t r o l s a r e
s om etim es u s ed f o r f a c i l i t i e s w i t h low c r i t i c a l r eq u i re m e nt s . Oncei t
i s s t a r t e d , s p ee d an d power a r e a u t o m a t i c a l l y r e g u l a t e d b y t h e e n g i n e
and t h e e l e c t r i c a l lo ad i s c o n ne c te d by t h e t r a n s f e r s w i t c h . The e n g i n e
g e n e r a t o r s h o u l d o p e r a t e a u t o m a t i c a l l y w it h o u t a d ju s t m en t o r o t h e r
a t t e n t i o n . T r a n s f e r o f power b ac k t o t h e p r i m ar y s o u r c e a n d s t o p p i n g
th e eng ine may be au toma t i c o r by remote con t r o l .
e 1 . L iq ui d f u e l f o r s e co nd ar y power i s u s u a l l y s t o r e d i n t a n k s
n e a r t h e e n g i n e g e n e r a t o r l o c a t i o n . The c a p a c i t y o f t h e f u e l t a n k s
shou ld be adequa te f o r t h e m a x i m um o p e r a t i n g t ime expec ted of t h e
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e n g i n e - g e n e r a t o r . Some a u t h o r i t i e s r eq ui re a minimum of 72 ho ur ss u p p ly . O t h er s d e s i g n f o r a l e s s e r ti m e p e r i o d , b u t t h e t i m e p e r i o d
u s u a l l y s h o u l d b e a t l e a s t t w i c e t h e maximum d u r a t i o n e x p e c t e d o f
c o n d i t i o n s t h a t c o u l d r e q u i r e t h e u s e o f s ec o n d ar y pow er. F u e l t a n k s
an d c o n ne c ti o n s s h o u l d meet a l l s a f e t y r e q u i re m e n ts a nd s h o u l d p r o v i d e
c o n ve n i en t a c c e s s f o r r e f u e l l i n g . T he se t a n k s s h o u ld a l s o p r o v i d e
a rr an ge me nt s f o r t e s t i n g f o r co n ta m in a ti o n of t h e f u e l , e s p e c i a l l y t h e
a c c um u l a ti o n of w a t e r i n t h e t a n k .
Power t r a n s f e r s w i t c h i n g
2.3.3.1 A s u i t a b l e t r a n s f e r d e v ic e i s n ee de d f o r t r a n s f e r r i n g power f r o m t h e p r im a ry
s o u r c e t o t h e s e co n da r y s o u r ce . F o r m an ua l s t a r t i n g a nd c o n t r o l t h i s may be a s i m p l e
s w i t c h o r r e l a y t h a t d i s c o n n e c t s t h e l o a d f r om on e power s o u r c e an d c o n n e ct s i t t o t h e
o t h e r . A d d i t i o n al c o n t r o l s a r e n eed ed f o r a u t om a t ic t r a n s f e r . T he se a r e u s u a l l y
co mbined i n t o a s i n g l e c o n t r o l u n i t o r c u b i c l e . Such a u n i t s h o u l d b e c a p a b l e o f
s e n s i n g t h e f a i l u r e o f p r im a ry pow er, i n i t i a t i n g t h e s t a r t i n g of t h e pr im e mover of t h e
s e c on d a ry g e n e r a t o r s e t , d e t e r m i n in g t h a t t h e v o l t a g e an d f r e q u e n c y of t h e g e n e r a t o r
h a ve s t a b i l i z e d a d e q u a t e l y , a nd c o n ne c t in g t h e l o a d t o t h e g e n e r a t o r . T h i s u n i t may
a l s o d i s co n n ec t n o n - e s s e n t i a l l o a d s a nd f a c i l i t i e s w hi ch a r e n o t t o be e n e r gi z e d by t h e
s e c on d a r y s o u r c e a nd t r a n s f e r t h e s e l o a d s b ack t o t h e p r i m ar y s o u r c e a f t e r t h a t power
h as b ee n r e s t o r e d . The s w i t c h e s o r r e l a y s f o r d i s c o n n e c t i n g a nd c o n ne c t i n g t h e l o a d
s h o ul d h av e t h e c a p a c i t y t o h a n d l e t h e r a t e d l o a d of t h e g e n e r a t o r . T h e f u n c t i o n i n g o f
t h e s e s w i t c h e s o r r e l a y s i s s i m i l a r f o r e i t h e r 2 a r in u te , 1 5 s ec o nd , o r l s e c o n d t r a n s f e r
t i m e s , a l t h o u g h more r a p i d - a c t i n g r e l a y s may be n ee de d f o r t h e s h o r t e s t t r a n s f e r t i m e .
For a 2 -minute t r an s fe r , t h e power f a i l u r e s e n s o r s may d e l a y a f ew s ec o nd s i n d e t e r -
m i ni n g i f th e pr imary power ha s f a i l e d o r i s o n ly f l u c t u a t i n g and a l s o t o d e te rm in e i f
t h e s e c o n da r y power h a s s t a b i l i z e d . F or a 1 5 s e c o n d t r a n s f e r , t h e s e n s o r s m us t r es po nd
i n l e s s t h a n 3 s ec on ds e ac h be ca us e t h e q u i ck s t a r t i n g e ng i n es n ee d 1 0 s e co n ds t o s t a r t
and t o s t a b i l i z e . F or t r a n s f e r t i me s of 1 s ec on d o r l e s s , t i m e i s t oo s h o r t t o s t a r t
t h e e n g i n e , b u t t h e l o a d c a n b e s w i t c h ed f r om o ne pow er s o u r c e t o a n o t h e r o p e r a t i n g
s o u rc e w ir h i n t h i s t i m e l i m i t ; h ow ev er , t h e pow er f a i l u r e s e n s o r ~ a s t e s p ~ n dwi thdn af e w c y c l e s .
2 .3 .4 Un in t e r r up t ib l e power su pp l i e s (UPS) sys t ems
2 .3 .4 .1 An u n i n t e r r u p t i b l e e l e c t r i c pow er s u p p l y i s n e ce s sa ry f o r e l e c t r o n i c o r
o t h e r e qu ip me nt t h a t p e rf or ms a c r i t i c a l f u n c t i o n and r e q u i r e s c o n t i n u o u s , d i s t u r b a n c e -
f r e e e l e c t r i c p ower t o o p e r a t e p ro p e rl y .
2.3.4.2 UPS equipment. The u n i n t e r r u p t i b l e power su pp ly (UPS ) s y st em c o n s i s t s o f
o ne o r more UPS m od ul es , a n e n e r g y - s t o r ag e b a t t e r y , a nd a c c e s s o r i e s a s r e q u i r e d t o
p r o v i d e a r e l i a b l e a rid h i g h q u a l i t y p ow er s u p p l y . The UPS s y s t e m i s o l a t e s t h e l o a d f r o m
t h e pr i m a ry a nd s e co n d a ry s o u r c e s an d i n t h e e v en t o f a p ow er i n t e r r u p t i o n p r o v i d e s
r e g u l a te d power t o t h e c r i t i c a l l o ad f o r a s p e c i f i e d p e r io d . (The b a t t e r y t y p i c a l l y ha sa 1 5 - m in u te c a p a c i t y when o p e r a t i n g a t f u l l l oa d . ) ( S ee F i g u r e 2 -2.)
a ) UPS modu le. A UPS module i s t h e s t a t i c power c o n v e r si o n p o r t i o n o f t h e
UPS s ys te m and c o n s i s t s of a r e c t i f i e r , a n i n v e r t e r , and a s s o d a t e d
c o n t r o l s a l on g w it h s y n c h r o ~ ~ i z i n g , r o t e c t i v e , a nd a u x i l i a r y d e v i c es .
UPS mo du le s may b e d e s i g n e d t o o p e r a t e e i t h e r i n d i v i d u a l l y o r i n
p a r a l l e l .
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b A nonred undan t UPS sy st em i s s u i t a b l e f o r mo st o p e r a t i o n s .
H ow ev er, i f t h e e x p en s e i s j u s t i f i e d , a r e d u n d a n t UPS c o n f i g u r a t i o n ( s e e
F i g u r e 2 -3 ) may be u se d t o p r o t e c t a g a i n s t m od ule f a i l u r e o r v e r y
f r e q u e n t p r im a r y po wer f a i l u r e s .
c > The b a t t e r y s h o u l d b e a h ea vy -d uty i n d u s t r i a l u n i t of t h e
l ea d-c ad miu m t y p e h a v i n g a n a mp er e- ho ur r a t i n g s u f f i c i e n t t o s u p p l y
d i r e c t c u r re n t t o t h e i n v e r t e r as r eq u i r ed by t h e UPS sys t em
m a nu f ac t ur e r' s i n s t a l l a t i o n i n s t r u c t i o n s . The b a t t e r y i s u s u a l l y
f u r n i s h e d w i t h t w o - t i e r r a c k s ; h o we ve r, w h e r e s p a c e i s l i m i t e d t h r e e-
t i e r r a c k s may be n e c e s s a r y .
d ) Remote a lar ms. The UPS equipment sh oul d be su pp l i ed w i t h a remote-a larm
p a ne l t o b e i n s t a l l e d i n t h e o p e r a t i n g s p ac e s er v e d by t h e UPS u n i t o r
i n a n o t h e r c o n t i n u o u s l y o c c u p i e d roo m, s u c h as a g ua rd o f f i c e . S in ce
UPS e q ui p me n t rooms a r e u s u a l l y u n a t t e n d e d , a d d i t i o n a l r e m o t e i n d i c a t i n g
d e v i ce s s h o u l d be p r o vi d ed t o m on i to r t h e e n v ir o n m en t a l c o n t r o l a nd f i r e
a la rm sys te m of UPS module and ba t t e r y rooms.
e ) UPS and b a t t e ry room requ i r em en t s . The UPS modul es and t h e i r a s so c i a t ed
b a t t e r y s e t s h o u ld b e i n s t a l l e d i n s e p a r a t e rooms. C o n s t r u c t i o n s h o u ld
be of a permanent type . The w a l l se pa ra t i ng t h e UPS modu l e room f rom
t h e b a t t e r y room s h o u l d b e f i r e p r o o f ( l- h ou r r a t i n g ) . When f e a s i b l e ,
s p a c e s h o u l d b e p r o v i d e d i n t h e UPS mo du le a n d b a t t e r y r oo ms f o r t h e
a d d i t i o n o f f u t u r e UPS eq u ip m en t .
f ) E n v i r on m e n ta l c o n t r o l . B ot h t h e UPS m od ul e a n d b a t t e r y r oo ms s h o u l d b e
p r o v id e d w i t h a n e n v i ro n m e n ta l c o n t r o l s y s t e m t o m a i n t a i n t h e p r e s c r i b e d
room c o n d i t i o n s . E ach e n v i r o n m e n t a l c o n t r o l s y s t e m s h o u l d c o n s i s t o f a
p r i m ar y s y s te m w i t h a se c o n d ar y s y s te m c a p a b i l i t y . Upon f a i l u r e o f t h e
p ri ma ry e n v i ro n m e n ta l c o n t r o l s y s t em , a u t o m a t i c t r a n s f e r t o t h e s e cs n d-
a r y s y st er n s h o u l d o c c u r a nd s h o u l d s ou nd a n a l a r m i n d i c a t i n g t h e n e edf o r m a in t en a nc e .
2.3.5.1 O th e r s e c o nd a r y p owe r d e v i c e s wh ic h may be u s e d f o r s p e c i a l f a c i l i t i e s a r es t a n d b y b a t t e r y p o w e r s ys te ms , w i t h o r w i t h ou t d c t o a c i n v e r t e r s ; p h o t o v o l t a i c o r wind
g e n e r a t o r s w i t h b a t t e r y s y s te ms a nd w i th o r w i th o ut d c t o a c i n v e r t e r s ; i n d ep e n d en t
g e n e r a t i n g d e v i c e s , s u ch as t h e r m o e l e c t ri c , n u c l e a r , o r c h em i ca l f u e l c e l l s ; a nd
i n e r t i a - f l y w h e e l g e n e r a t o r s . The m a n u f a c t u r e r ' s i n f o r m a t i o n s h o u ld e x p l a i n t h e
f u n c t i o n i ng and i n s t a l l a t i o n s f o r u s in g t h e s e d e v ic e s.
2. 4 VAULTS A N D SHELTEKS FOK ELECTRICAL EQUIPMENT
2. 4 . 1 She l t e r s
2 .4 .1 .1 Host e l e c t r i c a l e qu ip me nt f o r a i r p o r t L i gh t in g an d o t h e r f a c i l i t i e s i s
l o c a t e d i n v a ui c s o r s p e c i a i s h e l t e r s f o r p r o t e c t i o n f ro m t h e w ea th er a nd f o r b e t t e r
s e c u r i t y . S u b s t a t i o n s f o r h i g h v o l t a g e a r e u s u a l l y o u t d o o r s , a nd medium v o l t a g e
d i s t r i h ~ f i o n r a ns fo rm er % a r e o f t e n p o l e m ou nted o r p l a c e d on f e n c ed t r a n s f o r m e r p a ds .
H os t e l e c t r i c a l v a u l t s & r e a bo ve g ro un d aad made of f i r e ~ r o ~ faterials. P e i n f o r c e d
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5-1 2 Aerodrome Desinn I?lanual
UPS MODULE NO. 2PS NoDVLEm.1
BATTERY PACK
NONAUTOMATIC
CIRCUIT BREAKER
UPS OUTPUT T
CRITICAL BUS
F i g u r e 2 - 3 - i y p i c a i dP5 s tana-by r e du n na n t c o n f i g u r a t i o n
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c o n c r e te f o r t h e f l o o r s an d c o n c r e t e , c o n c r e t e o r c i n d e r b l o ck , a n d / o r b r i c k f o r t h e
w a l l s a r e m a t e r i a l s commonly u s ed i n t h e s e v a u l t s . Th e u s e of s u c h m a t e r i a l s r e d u ce t h
h az ar d of e l e c t r i c s ho ck , s h o r t i n g of e l e c t r i c a l c i r c u i t s , a n d f i r e h a z ar d s. P r e fa b r i-
c a t e d m e ta l s t r u c t u r e s a r e o c c a s i o n a l l y us ed a s s h e l t e r s f o r t r a n s f or m e r s a nd e ng in e-
g e n er a t or s e t s . These v a u l t s a r e u se d t o ho us e t h e p ower d i s t r i b u t i o n a n d c o n t r o l
equ ipment, s econda ry power equ ipment , and t h e va r i ous d ev i ces used t o p rov ide power and
c o n t r o l f o r t h e a i r p o r t l i g h t i n g s y st em s . These v a u l t s s h o ul d b e of a d e q u a t e s i z e t o
c o n t a i n t h e n e c e s s a r y e qu ip m en t w i t h o u t c ro wd in g. T h es e v a u l t s may b e d i v i d e d i n t o
rooms f o r b e t t e r s e g r e g a t i o n o f e qu ip me nt a nd a c t i v i t i e s .
2.4 .2 Loca t ion
2.4 .2 .1 E l e c t r i c a l v a u l t s s h o u l d n o t b e l o c a t e d wh er e t h e y w ould i n f r i n g e o n o b s t a -
c l e l i m i t a t i o n s u r f a c e s . The d i s t a n c e s fr om t h e c o n t r o l t ow er t o t h e v a u l t s sh o ul d be
s h o r t e no ug h t o a v oi d e x c e ss i v e v o l t a g e d ro p i n t h e c o n t r o l c a b l e s . T h e p e r m i s s i b l e
l e n g t h of t h e s e c ab l e s v a r i e s w i t h t h e s i z e of t h e c a b l e , t h e c o n t r o l v o l t a g e , and t h e
t y p e s of c o n t r o l r e l a y s u s ed , but some of t h e l o n g e r c o n t r o l s y st em s l i m i t t h e l e n g t h o
c o n t r o l c a b l e s t o a b ou t 2 250 m e tr e s. V e hi cu l ar a cc e s s t o t h e v a u l t s i n a l l t y p es of
w e a t h e r c o n d i t i o n s i s n e c es s ar y a nd minimum c o n f l i c t w i t h a i r c r a f t t r a f f i c i s d e s i r a b l eThe l o c a t i o n s h o ul d b e co n ve n ie n t f o r c o n ne c ti n g t o t h e a p p r o p r i a t e l i g h t i n g c i r c u i t s
and f a c i l i t i e s t o k eep f e e d er c a b le l e n g t hs a s s h o r t a s i s p r a c t i c a l . The v a u l t s s h o ul
b e i s o l a t e d f ro m o t h e r b ui l di n g s and f a c i l i t i e s t o pr e ve n t t h e s p r e ad of f i r e s o r
e x p l o s i o n s , e x c ep t t h e s h e l t e r s f o r s ec o n da r y e n g i n e - g e ne r a t o r s e t s may b e n e a r t h e
e l e c t r i c a l v a u l t t o r ed uc e c a b l e l e ng t h and s i z e and t o s i m p l i f y t h e p ower t r a n s f e r
sys tem. Aerodro mes w i t h a p p r o ac h l i g h t i n g s y s t e ms may n e ed s e p a r a t e a p p r o a c h l i g h t i n g
v a u l t s f o r ea c h a p p ro a c h l i g h t i n g s y st e m. F o r m a jo r a e r od r o m es , some a u t h o r i t i e s u s e a
v a u l t n e a r e a c h e nd of t h e runway o r a p pr o a ch l i g h t i n g s y s t em t o m ore e a s i l y a r r a n g e f o
i n t e r l e a v i n g of t h e l i g h t i n g c i r c u i t s and t o im prove i n t e g r i t y of t h e s ys te ms .
2.4 .3 S p e c i a l p r o v i s i o n s
2 = 4 + 3 . 1 A s s p e c i a l p ur po se b u i l d in g s , e l e c t r i c a l v a u l t s may r e q u i r e s p e c i a l f e a t u r et o p r o v i d e s a f e t y a nd r e l i a b l e p e rf o rm a nc e of t h e e q ui p me n t. Some o f t h e s e f e a t u r e s a r
a s f o l lo w s :
a ) V e n t i l a t i o n . P ro vi de a d eq u at e v e n t i l a t i o n t o p r e v e n t t r a n s f o rm e r
t e m p e r a t u r e s e x ce e d i n g t h e v a l u e s p r e s c r i b e d by t h e m an u f a ct u r e. Most
of t h e e l e c t r i c a l h e a t l o s s e s must be rem oved by v e n t i l a t i o n ; o n l y a
m in or p a r t c a n be d i s s i p a t e d by t h e v a u l t w a l l s . Some e l e c t r i c a l co de s
recommend 20 s q u ar e c en t i me t re s o f c l e a r g r a t i n g a r e a p e r k i l o v o l t -
a mp er e of t r a n s f o r m e r c a p a c i t y . I n l o c a l i t i e s w i t h a b ov e -a v er a ge
t em p er at u re s , s u ch a s t r o p i c a l o r s u b t r o p i c a l a r e a s , t h e g r a t i n g a r e a
s h o u l d b e i n c r e a s e d o r s up p le m en t ed by f o r c e d v e n t i l a t i o n .
b ) A cc es s. A de qu at e a c c e s s s h o u l d b e p r o v i d e d f o r r e p a i r s , m a i n t e n a n c e ,i n s t a l l a t i o n , a nd r em ov al o f e qu i pm e nt .
c ) Dra inage . A l l va u l t s shou l d be p rov ided wi th d ra in age . When norma l
d r a i n a g e i s n o t p o s s i b l e , p r o v id e a sump p i t t o p e r m i t t h e u s e of a
portable pump.
d j S e c ur i ty . Each e l e c ~ r i c a l a u i c s h ou l d b e e qu ip pe d t o d e t e r i n a d v er t e n
o r p r e m e d i t a t ed a c c e s s by u n a u t h o r i z ed p e r s o n s . T h i s s e c u r i t y i s
n e c e s s a r y t o p r e v e n t i n t e r f e r e n c e w i t h e qu ip me at o p e r a t i o n an d t o
p r o t s c t t h o s s persGns f r o m p ~ s s i b l e l e c t r i c s h ~ c k . Some rnerhods used
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a r e ba r r ed and s c re ened windows , heavy-du ty me ta l doors wi th pad locks ,a n d s e c u r i t y f e n ci n g.
e > . E l e c t r i c a l v a u l t s s h o ul d be w e l l i l l u m i n a t e d f o r u s ee i t h e r day o r n i g h t . T h is l i g h t i n g i s u s u a l l y p r ov id ed by i n t e r i o r
l i g h t s of a s i z e , t y p e, and l o c a t i o n t o p r ov id e good v i s i b i l i t y i n a l l
a r e a s. Poor v i s i b i l i t y c an i n c r ea s e t h e p o t e n t i a l f o r a c c i d e n t s
r e s u l t i n g i n e l e c t r i c a l s ho ck o r i mp ro pe r c o n t r o l a nd a d j u s t m e nt s .
f ) Local communicat ions. Most e l e c t r i c a l va u l t s shou ld be p rov i ded wi th
c o n v e n ie n t an d r e l i a b l e c om m un ic at io ns t o t h e c o n t r o l t o w er , o t h e r
v a u l t s , and p er ha ps o th e r f a c i l i t i e s o r o f f i c e s . S p e c i al t e le p ho n e o r
i n t e r co m m u n i c a ti o n s y st e m s may a v o i d o u t s i d e i n t e r f e r e n c e w i t h t h e s e
c i r c u i t s , b u t o t h e r d e p e nd a b le ar r a ng e m en t s c a n b e us e d.
g ) E l e c t r i c a l c o nd u it s . E l e c t r i c a l v a u l t s sh o u ld be p ro v id ed w i t h a
s u f f i c i e n t number of c o n d u i t s and c a b l e e n t r a n c e a c c e s s es t o a v o i d l a t e r
m o d if i ca t io n of t h e s t r u c t u r e t o pe rm it t h e i n s t a l l a t i o n o f a d d i t i o n a l
i n p u t o r o u t p ut c i r c u i t s . Th ese ca b l e s e n t r an c e s a r e u s u a l l y t hr ou g hu n de rg r ou n d c o n d u i t s wh ic h may b e c o n n e ct e d t o e x i s t i n g c a b l e d u c t s ,
d i r e c t - b u r i a l c a b l e s , o r unu sed c o n d u it s a v a i l a b l e f o r f u t u r e e xp an si on .
Unused co ndu i t s shou ld be p lugged , and co ndu i t s w i th cab le s shou ld be
s e a l e d .
h ) I n s t a l l a t i o n s of eq u ip m en t . A rr an ge t h e e q ui p me n t, e s p e c i a l l y t h e
l a r g e r i te m s su ch a s r e g u l a t o r s , d i s t r i b u t i o n t r a ns f or m er s , c o n t r o l
p a n e l s, an d c i r c u i t s e l e c t o r o r c o n t r o l d e v ic e s , t o p ro v i de a s i m p le ,
u n c l u t t e r e d , unc rowded p lan . Th i s a r rangement shou ld con s id e r s a fe ty ,
e s p e c i a l l y p r o t e c t i o n f ro m h i g h v o l t ag e e l e c t r i c a l c o n n e c ti o n s , a s w e l l
a s a c c e ss t o t h e eq ui pm ent and c o n t r o l s . The e l e c t r i c a l c i r c u i t s sh o ul d
a i s o be a r r a n g ed i n a s im p l e p a t t e r n w he re ve r p o s s i b l e . F o ll ow t h e
a pp l i ca b l e e l e c t r i c s a f e t y c odes f o r i n s t a l l i n g a l l e l e c t r i c a l c i r c u i t sa n d c o n t r o l s .
2 .5 DISTRIBUTION OF POWER
2 .5 .1 Genera l
2 . 5 . 1 . 1 The eq uip men t d i sc u s se d i n t h i s s e c t i o n r e l a t e s o n l y t o t h a t u s ed i n
t r a n s m i t t i n g e l e c t r i c a l power f o r t h e aer od ro me l i g h t i n g a nd r a d i o n a v i g a t i o n a i d s
b etw een t h e m ai n a er od ro me s u b s t a t i o n ( s ) a nd t h e l i g h t i n g v a u l t s o r t h e l o c a l s i t e
d i s t r i b u t i o n t r a n sf o r m e r s. D e s c r ip t i o n s o f eq ui pm en t a r e i n g e n e r a l te rm s o f c h a r a c t e r -
i s t i c s an d n ee ds and u s u a l l y a r e n ot r e l a t e d t o s p e c i f i c t y p e s o r i te m s o f e q u ip m en ts .
Types of equipment and number of devices w i l l v a ry g r e a t l y w i t h t h e s i z e a n d c o mp l ex i t y
of t h e aerodrome. Economics i s a n im p o rt a nt p a r t of i n s t a l l a t i o n s , a nd o n l y e qu ip me nt
w hich c o n t r i b u t e s t o p er fo rm an ce , s a f e t y , r e l i a b i l i t y , and i n t e g r i t y s h ou l d be used .
T h e c i r c u i t s a nd eq ui pm en t us ed s h o u l d p r o v i d e f o r a r e a s o n ab l e e x p an s io n of f a c i l i t i e s w
E f f i c i e n t u s e of e l e c t r i c a l power i s a lw a ys a d e s i r a b l e g o a l , b u t t h e po we r c o s t f o r
a er od ro me l i g h t i n g an d r a d i o navigation a i d s i s u s u a ll y a r a t h e r s m a ii p a r t o f t h e t o t a l
aerodrome ene rgy co s t and shou ld no t be emphasized t o the po i n t o f ov e r l y i nc re as in g
l r i s t a l l a t i o n c o s t s 01- of d i m i n i s h in g p e r fo r m a~ l c e, s a f e t y , o r r e l i a b l l i t y i F o ll o w r h e
l o c a l e l e c t r i c a l s a f ec y co de s.
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2.5.2.1 Primary power i s u s u a l l y r ed uc ed i n v o l t a g e a t t h e main a e ro dr om e s u b s t a t i o
f o r d i s t r i b u t i o n o n t h e a er od ro me . F o r m a jo r a e r od r o m es , t h i s pow er a t t h e f i r s t s t a ge
may b e a t a n i n t e r m e d i a t e v o l t a g e ( u s u a l l y 5 000 t o 20 000 v o l t s ) , b u t f o r s m a l l e r, l e s
complex ae rod romes, t h i s power may be d i s t r ib u t ed a t a medium vo l t ag e (u su a l ly 1 000 t o
5 000 v o l t s ) . The d i s t a n c e and t o t a l lo a d on t h e c i r c u i t a r e im p or t an t f a c t o r s i n
d e t er m i n in g t h e v o l t a g e l e v e l o f t r a ns m i s si o n . F o r a n i n t e r m e d ia t e - v o lt a g e d i s t r i b u t i o
sys tem, power i s o f t e n r u n t o s u b s t a t i o n s n e ar l a r g e p ower u s a g e a r e a s w h er e i t i s
r ed uc ed t o medium v o l t a g e f o r l o c a l d i s t r i b u t i o n . A c o m b in a t io n o f t h e s e v o l t a g e
d i s t r i b u t i o n s y s te m s may b e u s e d . Primary power i s t r a n s m i t t e d f ro m t h e m ain s u b s t a t i o n
t o t h e l o c a l s u b s t a t i o n o r d i s t r i b u t i o n s i t e s u s ua l l y as m u l ti - p ha s e c i r c u i t s by a bo ve
g ro un d ( o v er h e ad ) c i r c u i t s , u n de rg r ou n d c i r c u i t s , o r a co m bi n at io n o f t h e s e c i r c u i t s .
Above g rou nd c i r c u i t s a r e l e s s e x pe ns iv e t o i n s t a l l a nd a r e u s u al l y u s ed i f f e a s i b l e ,
b u t t h e s e c i r c u i t s may b e more e x po s ed t o damage a n d i n some a r e a s a r e a h a z a r d t o
a i r c r a f t a nd c r e a t e e l e c t r o m a g n e t i c i n t e r f e r e n c e f o r o t h e r e qu ip m en t. U nd er gr ou nd
f e e d e r c a bl e s a r e u s u a l l y i n s t a l l e d i n d u c t s , b u t s ometimes d i r e c t b u r i a l i s used . Eac
t y p e of c i r c u i t , w h et h er o v er h ea d o r un de rg ro un d, i n v o l v e s s p e c i f i c t y p e s o f e qu ip me nt
and de s ign .
2 .5 .3 Above-ground (ove rhead ) p r imary d i s t r i b u t io n sys t ems
2 .5 .3 .1 The f o l l o w i n g f a c t o r s s h o u l d b e c o n s i d e r e d i n t h e d e s i g n o f a n o v e rh e a d
power d i s t r i b u t i o n s y st em :
a ) A p p li c at i o n. Use o ve rh ea d d i s t r i b u t i o n i n l i e u of u nd er gr ou nd d i s t r i b u -
t i o n wh er ev er f e a s i b l e .
b ) C a pa ci ty . P ro vi de f o r s p a r e c a p a c i t y i n e a ch p o r t i o n of t h e c i r c u i t .
P eak l oa d s do no t r e l a t e d i r e c t l y t o s p a r e c a p a c i t y .
c ) W ire s i z e . S e l e c t t h e w i r e s i z e i n a c c or d a nc e w i t h t h e c u r r e n t - c a r r y i n gc a p a c i t y r e q u i r e d a n d, w h er e a p p l i c a b l e , t h e vo l t ag e - dr o p l i m i t a t i o n .
2.5.4 L i n e v o l t a g e r e g u l a t o r s
2.5.4.1 R e g u l a t o r s a r e u s e d f o r c o r r e c t i o n o f 1 i n e v o Z t a g e v a r i a t i o n s r e s u l t i n g f ro m
c h an g in g l o a d s o r u t i l i t y company i n p u t v o l t a g e ch an ge s. Do n o t u s e t h e s e r e g u l a t o r s t o
c o r r e c t f o r ex c e s s i v e v o l t a g e d r o ps . B o os te r t ra n s f o r m e r s w hich c o r r e c t f o r v o l t a g e
d r op s h ou ld be us ed o n l y i n r a r e i n s t a n c e s a s , i n most c a s e s , c o r r e c t d e s i g n e l i m in a t e s
e x c e s s i v e v o l t a g e d r o p .
a ) R a ti n g. C hoose t h e r a t i n g o f t h e r e g u l a t i n g d e v i c e s i n a c co r d an c e w i t h
th e amount of r ebw la t io n requ i r ed .
b ) S e l e c t i o n . C hoos e t h e t y p e o f r e g u l a t o r s f r om f i x e d c a p a c i t o r s ,
s w i t ch e d c a p a c i t o r s , m u l t i s t e p ( m o to r- dr iv en t a p c ha n g in g ) r e g u l a t o r s ,
a nd i n d u c t i o n ( s t e p l e s s v o l t a g e c h an g e) r e g u l a t o r s .
c ) M u l t i s t e p o r i n d u c t io n r e g u l a t o r s . P ro vi de l i n e d r o p c om pe ns at io n f o r
a u t o m a t i c o p e r a t i o n when t h e s e r e g u l a t o r s a r e u se d o n more t h a n o n e
sour ce o r when more than one re gu la to r i s used on a s i n g l e c i r c u i t .
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Power l i n e s
2.5.5.1 S e l e c t t h e t y p e o f power l i n e s i n a c c or d a nc e w i t h t h e t y p e o f c i r c u i t
i n v o l v e d an d t h e c o n d i t i o n s t o w hi ch i t i s s u b j e c t e d f r om t h e f o l l o w i n g :
a ) Open w i r e ( b a r e o r w e a t h e r p r o of ) on i n s u l a t o r s .
b ) A e r ia l c ab l e, s e l f s u p p o r t e d o r s up po rt ed by a h i g h s t r e n g t h s t e e l
( m es s en g er ) c a b l e , c o n s i s t i n g o f i n s u l a t e d , b u nd l ed , s i n g l e - c o n du c t o r
c a b l e o r m u l t i p l e - c o n d u c t o r c a b l e .
P o le s . Wood, c o n c r e t e ( r e i n f o r c e d w i t h p r e s t r e s s i n g o r p o s ta ) Pe n s i o n i n g ) , o r m e t a l ( s t e e l o r al um in um ) may b e u s ed . C o n c r e t e o r
m e t a l p o l e s s h o u l d b e u s ed o n l y w he re t h e y a r e more e c o n o m i c a l o r
s p e c i a l c o n s i d e r a t i on s w a r ra n t t h e i r u se .
b ) F o o t in g s . P r ov i de f o o t i n g s , o r r e i n f o r c em e n t s o f t h e p o l e b u t t - e n d , a sr e q u i r e d by f o u n d a t i o n c o n d i t i o n s .
c ) C o n f ig u r at i o n. A rm les s c o n s t r u c t i o n f o r a e r i a l l i n e s i s u s u a l ly l e s s
c o s t l y t h a n c r o s s ar m c o n s t r u c t i o n a nd i t s u s e i s p r e f e r r e d , as i s m u l t i -
c or ld uc to r s e co n da r y c a b l e w i t h a l a r g e n e u t r a l c o n d uc t o r a s t h e s u p p o rt -
in g member ove r in d i v i du a l supp or t ed conduc to r s . Use c ros sa rm s ma in ly
f o r e q ui pm e nt s u p p o r t .
d ) Guys a nd a n c h o r s . P r o v id e g uy s a nd a n c h o r s t o s u p p o r t p o l e s o r l i n e
t o we r s a g a i n s t h o r i z o n t a l un b al an c ed l o a d s c au s ed by a n g l e s , c o r n e r s ,
a nd t e r m i n a t i o n s of l i n e s a n d w he re r e q u i r e d b e c a us e o f e x t r e m e w in d
l o a d i n g s . C o n s u lt m a n u f a c t u r er s 7 c a t a l o g u e s f o r t y p e s o f e a r e h anchors
a nd d e s i g n d a t a . S e l ec t equipm ent s u i t a b l e f o r t h e p a r t i c u l a r s o i lc o n d i t i on s a nd t h e c o n s t r u c t i o n m t h o d t o b e us ed .
2.5.6 Conductors
2 .5 .6 .1 S i z e l i m i t a t i o n s . L i mi t t h e u s e o f p o l e - l i n e c o n du c t or s i n a c c o r d a n c e w i t h
T a b l e 2-2 f o r a n e co no m% ca l s y s t e m f r o m t h e i n s t a l l a t i o n , o p e r a t i o n a l , a nd m a in t e na n c e
p o i n t s of vi ew . S p e c i a l i r l s t a n ce s may r e q u i r e l a r g e r c o n du c t or s . I n a l l i n s t a n c e s b e
s u r e t h a t t h e t yp e an d s i z e of c o nd u ct or s u se d p ro v i de s a d e q u at e s t r e n g t h f o r t h e s p an
l e n g t h s a nd l o a d i n g c o n d i t i o n s .
Table 2-2
Conductor type
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2.5.6.2 B as e w i r e s i z e on t h e r a n g e s shown i n T a b l e 2-2 . Pr imary w i re
s i z e s u s u a l l y s h ou ld n o t b e l e s s t h a n 13.0 mm2 coppe r o r 33 .0 mm2 aluminum. For prim ary
c o n d u c t or s , s e l e c t fr om t h e f o ll o w i n g :
a ) B ar e c o pp e r c o n d u c t o r, s t r a n d e d o r s o l i d c o pp e r.
b ) Ba re a luminum-a lloy condu c to r , s t r a nde d o r s o l i d a luminum-a l loy .
c ) B ar e aluminum c o n d u c to r , s t e e l r e i n f o r c e d .
d ) B ar e h i g h s t r e n g t h a ll -a lu mi nu m a l l o y co n d uc t or .
2.5.6.3 S p e c i a l c o n d u c t o r s . I n s p e c i a l i n s t a n c e s , u s e of t h e f o l l o w i n g c on d u ct o r s
may b e a p p r o p r i a t e f o r p r i m a ry c o n d u c t o r s :
a ) I n s u l a t e d c o n d u c t o r , c o p pe r o r al um in um , p r e a ss e m b le d n o n - m e t a l l i c -
s h e a t h e d o r m e t a l l i c - s h e a t h e d , s t e e l - ca b l e - s u p p or t e d (messenger-
s u p po r t ed ) a e r i a l c a b l e i s u s e d w he re n e c e s s a r y t o a v o i d e x p o s u r e t o
o pe n w i r e h a z a r d s , f o r e xa mp le , h i g h r e l i a b i l i t y s e r v i c e i n h eav y s t or ma r e a s .
b ) Compound conduc to r ma te r i a l s such a s coppe r -c lad s t e e l , a luminum-clad
s t e e l , g a l v a n i z e d s t e e l , o r b ro nz e a r e u s ed t o p r o v id e h i g h s t r e n g t h and
c o r r o s io n r e s i s t a n c e .
2.5 .6 .4 Dis s im i la r conduc to r s . Where i t i s neces sa ry t o connec t a luminum cond uc to r s
t o co p pe r c o nd u c to r s , a p p r o p r i a t e c o n n e c t o r s s p e c i f i c a l l y d e s i g ne d f o r s u c h u s e s h o u ld
be i n s t a l l e d i n ac co r da nc e w i t h t h e i n s t r u c t i o n s o f t h e m a nu f ac tu r er .
2.5.7 I n s u l a t o r s
2,5 ,7 ,1 T yp es of i n s u l a t o r s - S e le c t f r o m t h e f o l l o w i n g l i s t t h e ty p e of i n s u l a t o rt o s u p p o r t b a r e o r we at h er p ro o f i n s u l a t e d c o n d u c to r s .
a ) S us pe ns io n t y p e , s i n g l e o r m u l t ip l e .
b ) Spoo l type .
c ) L i n e - p o s t t y p e ( o n e - p i ec e p o r c e l a i n on a b o l t f o r mo u nt i ng o n c r o s s a r m s
o r on a s a d d l e on t h e s i d e of a p o l e ) .
d ) S t r a i n t y p e ( s us p en s io n u n i t s w i t h s t r e n g t h e q u a l o r e x ce e di n g t e n s i l e
s t r e n g t h of t h e c o n du c to r u s u a l l y h av in g one t o t h r e e e x t r a d i s k
s e c t i o n s a nd a r c i n g h or n s o r r i n g s ) .
e ) P i n t y p e ( p o r c e l a i n , u s u a l l y two o r more s e p a r a t e s h e l l s ce me nt ed
t o g e t h e r , w i t h a n i n t e r n a l t h r e a d f o r s c r e wi n g o n t o a wood o r m e t a l
p i n ) .
f ) Combina t ions . Va r ious typ es o f in su la to r s may be combined ; fo r example ,
s t r a i n t y p e f o r a nc ho r p o le s o r t e rm i n at i on s w i t h e i t h e r p i n o r l i n e -
p o s t t y p e s f o r l i n e i n s u l a t i o n . L i ne -p o st t y p e s a r e c o n s i d e re d t o be
b o th l e s s e x p e ns i ve a nd s u p e r i o r t o p i n t y p es .
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2.5.7.2 I f o ve rh ea d l i n e s a r e u s ed i n l o c a t i o n s e n s i t i v e t o e l e c t r o m a g n e t i c i n t e r -
f e r e n c e , t h e i n s u l a t o r s s h o ul d b e of a s t a t i c - f r e e t yp e .
2.5.8 Locknuts
2 .5 .8 .1 Hardware componen ts shou ld be p rov ided w i th loc knu t s t o avo id lo os e connec t -
io ns wh ich cou ld cause s t a t i c . Locknu t s mus t be th rea ded and o f a type wh ich w i l l
pre ven t l oo se ni ng of th e conn ect ion when wood members sh ri nk .
2 .5 .9 Transfo rmers
2 .5 .9 .1 Mount t r an s fo rme rs on po l e s o r a t g r o u n d l e v e l .
When sh ee t me ta l enc lo su r e s a r e no t t ampe rp roo f , g round moun ted u n i t s shou ld be p rov ided
w i t h a f e n c e d e n c l o s u r e . A c o n c r e t e o r b r i c k s t r u c t u r e s h ou l d be us e d wh er e a d v e r s e-
w e a th e r c o n d i t i o n s make s u c h a n i n s t a l l a t i o n a d v i s a b l e .
a 1 F o r s i n g l e - p o l e m o u n t i n g , l i m i t t h e s i z e o f
s i n gl e - ph a s e o r t h re e- p ha s e u n i t s i n a cc o r da n ce w i t h a p pr o ve d p r a c t i c e s .
b ) Po le -p la t fo rm moun t ing . Po le - p la t f o rm mount ing ( two-po le s t r u c t u r e s )
s h o ul d n o t b e u s ed , e x c e p t i n i n s t a n c e s w he re o t h e r m e th od s a r e n o t
s a t i s f a c t o r y . F or i n s t a l l a t i o n s of 225 o r 500 k i lo v o lt - am p e rs ,
pad-mounted compartmenta l- type t r an sf or me rs become an a t t r a c t i v e
e co no mi c a l t e r n a t i v e t o p ol e- mo un te d u n i t s *
c ) Ground mou n t i ng For g round mount ing on a con c re te ba s e , t h e r e i s n o
k i lovo l t - ampe re l i m i t . U s u al l y t am pe rp ro of t r a n s f o r m e r s ( c l a s s i f i e d a s
g ad -m o un te d c o mp a rt m en ta l -t yp e u n i t s ) s h o u l d n o t b e s p e c i f i e d f o r
r a t i n g s o f o v e r 5 00 k i l o v o l t -a m p e r e s .
2 .5 .9 .2 R a t i n g s . S e l e c t t r a n s f o r m e r s w i t h s t a n d a r d k i l o v o l t- a m p e r e r a t i n g s a n d
i n p u t and o u t p u t v o l t a g e a s s ing le -phase o r th ree-phase u n i t s , T r a n s f o r m e r s w i t h i n p u tv o l t a g e t a p s f o r s e l e c t i n g t h e most s u i t a b l e i n p u t v o l t a g e l e v e l may be d e s i r a b l e f o r
s o m e i n s t a l l a t i o n s .
2 .5 .9 .3 Indoor in s t a l l a t i o n s . O il -immersed ( f l ammab le ) t r ans fo rm ers shou ld no t be
i n s t a l l e d i nd o o rs e x c ep t i n v a u l t s c on fo rm in g t o t h e r e q u ir e m en t s of t h e a p p l i c a b l e
e l e c t r i c c o de . S uch v a u l t s s h o u l d b e p r o v i d e d o n l y when o t h e r t y p e s of t r a n s f o r m e r s a r e
l e s s e co n om i ca l o r a r e p r o h i b i t e d by s p e c i a l c o n s i d e r a t i o n s . Where s u c h a v a u l t i s no t
p r o vi d ed , s e l e c t t ra n s fo r m er s f o r i n d oo r i n s t a l l a t i o n f ro m t h e f o l l o w in g :
a ) h i g h - f i r e - p o i n t , l i q u i d - i m m e r s e d ;
b) dry- type , v e n t i l a t e d ;
c ) d r y -t y p e, s e a l e d t a n k ; a n d
d) nonhaza rdous ga s - in su l a t ed .
2 .5 .9 .4 T o xi c i n s u l a t i o n f l u i d s . The t r a n s f o r m e r s s h o u l d n o t u s e p o l y - c h l o r i n a t e d
b i p h e n y l (PCB) o r o t h e r h i g h l y t o x i c i n s u l a t i o n f l u i d s . L ea ka ge o r m i s h a n d l i ng o f t h e s e
c h e m i c a l s d u r i n g m a i nt e n an c e t e s t i n g c a n b e h az a r do u s t o p e r s o n n e l .
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2.5.10 Capaci tors
2,5.10.1 Use shun t c a pa c i t o r s t o i mprove t h e powe r f a c t o r o f
t h e l o a d c a r r i e d by t h e c i r c u i t . I n a p p ly i n g c a p a c i t o r s , c o n s i d er t h e f o ll o w in g :
a ) F i xe d c a pa c i t a nc e . F i xe d c a pa c i t a nc e i s t h e amoun t o f c a p a c i t a n c e t h a t
c a n be a p p l i e d c o n t i n u o u s l y w i t h o u t e x c e s s i v e v o l t a g e r i s e a t r ed uc ed
load .
b) Swi tched capac i tanc e . Switched cap ac i tan ce i s a n a dd i t i o na l a mount o f
c a p a c i ta n c e t h a t c a n be a p p li e d , i f p r o v i s i o n i s made t o s w i t c h o f f t h i s
ad di t i on a l amount a t r educed demand.
c ) C a p a c i t o r s w i t c h in g . S e l e c t a t y p e o f c a p a c i t o r s w i t c h i n g t h a t i s
s u i t a b l e f o r t h e co n d i t i o n a t hand. P o s s i b l e c ho i ce s i n c l u d e re mo te
c o n t r o l o f t h e c a p a c i t o r s w i t c h i n g d e v i c e , t i me -c lo ck c o n t r o l , p ower-
f a c t o r r e l a y c o n t r o l o r v ol t a ge - se n s it i ve r e l a y c o n t r o l.
2 .5 .1 0. 2 L o c at i o n of c a p a c i t o r s . I n s t a l l c a p a c i t o r s i n b an ks on p o l e s , a t g ro un dl e v e l , o r i n a s u b s t a t i o n a s ne a r l y a s p o s s ib l e t o t h e c e n t ro i d o f t h e a r e a where
c o r r e c t i o n i s r e qu i r e d .
2 .5.11 C i r c u i t i n t e r r u p t i o n d e v i c e s
2.5.11.1 F u se s. A f t e r c o n s i d e r a t i o n o f t h e n e c e s s ar y c u r r e n t - c a r r y i n g c a p a c i t i e s ,
i n t e r r u p t i n g d u t i e s , and t im e -c u rr en t m e l t i n g and c l e a r i n g c h a r a c t e r i s t i c s , s e l e c t f u s e s
f ro m t h e f o l l o w i n g t y p e s :
a ) o pe n f u s i b l e l i n k ;
b ) e x p u l s i o n t y p e ;
c ) bo r i c - a c i d t ype ; a nd
d ) c u r r e n t - l i m i t i n g t y p e .
2 .5 .1 1. 2 C i r c u i t b r e a k e rs . C o - or d in a t e t h e c i r c u i t b r e a k e r r a t i n g w i t h t h e l o a d
i n t e r r u p t i n g du t y and w i t h c i r c u i t b r e a k e r s and f u s e s a he ad of o r a f t e r t h e c i r c u i t
b r e a ke r .
2 .5 .11.3 A u tom at i c c i r c u i t r e c l o s e r s . Use of a u t om a t i c r e c l o s e r s f o r o t he r t ha n
overhead l i n e loads may cause problems f rom h ig h- r es i s ta nce ground f a u l t s . I f an au to-
m a ti c c i r c u i t r e c l o se r i s u s ed , c o n s i d er t h e r e l i a b i l i t y a nd c o n t i n u i t y re q u ir e me n t s o f
t h e s e r v i c e . R e c l o s e rs may c o ns i s t o f a c i r c u i t - b r e a k e r o r m u l t i p l e s w i t c h i n g d e v i c e s .
R e c lo s e rs o p e r a t e s o t h a t a f a u l t e d c i r c u i t may b e op en ed a nd t h e n , e i t h e r i n s t a n t a n e -o u s l y o r w i t h d e l i b e r a t e ti me d e la y , r e c l o se d . Up t o t h r e e r e c l o s u r e s w i t h v a r yi n g t i m e
i n t e r v a l s may be u se d. C o -o rd i na t e a u t om a ti c c i r c u i t r e c l o s e r s w i t h f u s e s o r c i r c u i t
b r e a k e r s on t h e same c i r c u i t .
2 .5 .11. 4 S w it c hes . Use s w i t c he s t o l o c a l i z e de f e c t i ve po r t i o ns o f a e r i a l a nd unde r-
g r ound c i r c u i t s a nd t o a c c om pl i s h de a d - c i r c u i t work. S e l e c t f rom one o f t h e f o l l ow i ng
p r i n c i p a l t y pe s:
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a ) Non load -b reak sw i t c hes . Use non load -b reak s w i t ch es on ly f o r t h e in t e r -t c a r r y no a p p r e c i a b l e l o ad . S e l e c t t h e t y p e
a p p l i c a b l e , d e pe nd i ng o n c i r c u i t i mp o r ta n ce , l o a d , v o l t a g e , a n d f a u l t
c i r c u i t d u t y. The t y p e s a v a i l a b l e a r e p o r c e l a i n d i s c o n ne c t f u s e
c u t o u t s , p l a i n o r f u s ed s i n gl e - p o l e a i r di s co n n ec t s w i t c h e s , a nd
d i s c o n n e c t f u s e c u t o u t s of v a r i o u s t y p e s . D i s c o n n e ct i n g a nd h or n- ga p
swi t ches may a l s o be u sed a s non load -break sw i t ch es ,
b ) L oa d- br ea k s w i t c h e s . b a d - b r e a k s w i t c h e s a r e p r o vi d ed w i t h a n i n t e r -
r u p t i n g d e v i c e c a p a b le o f d i s c o n n e c t i n g c i r c u i t s u nd e r l oa d . F us e
c u t o u t s , w hi ch a r e d e si g n ed t o b e l oa d -b r ea k a nd l o a d - i n t e r r u p t e r
s w i t c h e s , a re av a i l ab le . Vacuum swi t ches a l s o p rov ide load -b reak
c a p a b i l i t y .
2 .5 .1 2.1 To d e t e r m i ne t h e r e q u i r e m e n t s f o r l i g h t n i n g p r o t e c t i o n , c o n s i d e r o v e r h e a d
g ro un d w i r e , o pe n o r e x p u l s i o n g a p s, a nd d i s t r i b u t i o n - t y p e s u r g e ( l i g h t n i n g ) a r r e s t e r s .
The w e a t h e r s h o u l d a l s o b e c o n s i d e r e d . P r o t e c t i o n f o r l ig h t n i n g -i n d u c e d s u r g e s may b eu n n ec e s sa r y i n a r e a s w he re a nn u a l l i g h t n i n g s to r m s a r e few . A d m i n i s t r a t i v e p o l i c y o r
l o c a l e l e c t r i c power company p r a c t i c e s h o u l d u s u a l l y b e fo l lo w e d. S e l e c t t h e p r o p e r
a r r e s t e r i n a cc o rd an c e w i t h t h e c h os en b a s i c i mp ul se i n s u l a t i o n l e v e l f o r w hi ch t h e
c i r c u i t must b e b u i l t .
2 .5 .13 Clearances
2 .5 .1 3.1 P r ov i de t h e n e c e s s a ry h o r i z o n t a l an d v e r t i c a l c l e a r a n c e s f r o m a d j a c e n t
p h y s i c al o b j e c t s , s uc h a s b u i l d in g s , s t r u c t u r e s , and o t h e r e l e c t r i c l i n e s , a s r eq ui r ed
by t h e a p p l i c a b l e e l e c t r i c a l s a f e t y c od e. P ro vi de a g a i n s t c o nt in g en c y i n t e r f e r e n c e s ,
s u c h as b r o ke n p o l e s , b r o k e n c r o s s a r m s , a nd b r o ke n c i r c u i t c o n d u c t or s . P r o v i d e f o r
c l e a r a n c e c o n d i t i o n s a r i s i n g f r o m m u .l ti p ur p os e j o i n t u s e of p o l e s . !%e t h e a p p l i c a b l e
e l e c t r i c a l s a f e t y co de f o r cl i m bi n g s p a c e c l e a r a n c e s , j o i n t u s e , a nd su p p ly c o n du c to rp r o t e c t i o n .
2.5.14 Grounding
2 .5. 14. 1 F or i n f o r m a t i o n on g r o u n d i n g o f o v e rh e ad d i s t r i b u t i o n s y s t e m s , u s e t h e
a p p l i c a b l e e l e c t r i c a l s a f e t y c od e o r A d m i n i s t ra t j v e p o l i c y. F or s a f e t y p r o v i d e grnund-
i n g f o r a l l eq ui pm en t an d s t r u c t u r e s a s s o c i a t e d w i t h e l e c t r i c a l sy st em s t o p r e v en t s h oc k
f rom s t a t i c o r dynamic vo l t ag es . Maximum g round re s i s t an ce sho u ld no t exceed va lue s
s p e c i f i e d i n t h e ap p l i c ab l e e l e c t r i c a l s a f e t y co de . C on si de r t h e s o ur ce of e l e c t r i c
power , c a pa c i t y , magn i tude o f f a u l t cu r r en t , and method o f sys t em g round ing , a s they
a f f e c t t h i s r e s i s ta n ce .
2 .5 .14.2 Ground rods . Ground rods may be u sed e i t h e r s i ng ly o r i n c lu s t e r s . Dr ivet h e gr ou nd r o d s t o gr ou nd w at e r l e v e l f o r a n e f f e c t i v e a nd pe rm an en t i n s t a l l a t i o n .
P r o vi d e f o r c o r r o s i o n p r e v e n ti o n by a p r o p e r c h o i c e of m e t a l s o r by c a t h o d i c p r o t e c t i o n .
Where ground water cannot be reached, chem ica ls s uch a s magnesium su lp ha te (MgS04) or
coppe r su lp ha t e (CuSO,+) may be u sed t o improve s o i l cond uc t iv i ty whe re ne ce s sa r y . Manu-
f a c t u r e r s of g r o un d r o d s c a n p r o v i d e d a t a o n s u c h t r e a t m e n t . P r o v i d e f o r e a s y m a in t e-
n a n c e a n d p e r i o d i c t e s t i n g . A l though d r i v i ng g round rods deepe r ( s ec t i on a l ty pe ) may be
more e f f e c t i v e t h a n m u l t i p l e r o d s , i n many c a s e s , s o i i v a r i a t i o n s a nd p o s s i b l e be dr oc k
may make p r o v i s i o n o f a d d i t i o n a l r o d s l e s s e x p e n s iv e .
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2.5.14.3 A bur ied ne twork o f g round conduc to r s w i l l a s s u r e a n
e f f e c t i v e s a f e t y g round i n p oo r s o i l an d w i l l e l i m i n a te l a r g e v o l t a g e g r a d i e n t s a t
s u b s t a t i o n s f o r u t i l i t y a er od ro me i n t e r c o n n e c t i o n s . Mesh s p a c i n g s o f 3 t o 3.5 m e t r e s
a r e commonly used and us ua l l y such spa c ings c an c o n t r o l s u r f a c e v o l t a g e g r a d i e n t s even
t h o ug h t h e gr ou nd r e s i s t a n c e may be r e l a t i v e l y h i g h .
2.5.14.4 Wate r p ipe connec t ions . The e l e c t r i c a l s y s t em may b e gr o u n de d t o a w a t e r
s u p p l y s y s t e m e x c e p t w he re n o n m e t a l l i c p i p e s , c a t h o d i ca l l y p r ot e c t e d m e t a l l i c p i pe s , o r
i n s u l a t i n g c o u p l in g s a r e i n c o r p o r a t e d i n t h e w a t e r p i p e s y st em . The wa te r p ipe connec -
t i o n s h o u l d be s u pp l em e nt e d by o t h e r g r ou n d i ng e l e c t r o d e s w he re r e q u i r e d b y t h e
a p p l i c ab l e e l e c t r i c a l s a f e t y c ode.
2 .5 .14.5 Combinat ion of groundin g methods. Where t h e ground r e s i s t a n c e i n a n
e x i s t i n g s y s te m i s hi gh , two o r more of t he afo rem entio ned methods may be combined t o
e f fec t improvemen t .
2 .5 .14.6 Ground connec t ions . Wi res runn ing f rom p r o t ec t i ve dev ice s ( f o r example ,
g a p s , g r a d i n g r i n g s , e x p ul s i on o r p r o t e c t i o n t u b e s , and s u r g e a r r e s t e r s ) t o gr ou nd
s h o u ld be ke p t a s s t r a i g h t and s h o r t a s p o s s ib l e . Where bends a r e nec e ss a ry they sh ou ldb e of l a r g e r a d i i t o k e e p t h e s u r g e i m pe da nc e a s l ow a s p o s s i b l e .
2.5.14.7 Ove rhead g round w i re s . Where ove rhead g round w i r e s a r e u sed f o r p r o t ec t i on
o f e l e c t r i c l i n e s , a gr ou nd c o n ne c ti o n s h ou l d b e p r o v id e d a t t h e b a s e of e a c h po l e f ro m
t h e o v er h ea d gr ou nd w i r e t o a w i r e l o o p o r a g ro un d p l a t e o r t o a d r i v e n r o d , d e pe n di n g
o n t h e e x i s t i n g s o i l co n d i t i o n s. Use o f wi r e w ra ps o r p o le b u t t p l a t e s i s a l lowed on ly
i n a r e a s of v er y low s o i l r e s i s t i v i t y .
2.5.14.8 Measurement of ground r e s i s t a n c e . Two methods of meas urin g gro un d
r e s i s t a n c e a r e:
a ) T h r e e - e l e c tr o d e m eth od . I n t h e t h r e e - e l e c t r o d e m e th od , t wo t e s t e l e c -
t r o d e s a r e u s e d t o m ea su re r e s i s t a n c e of t h e t h i r d e l e c t r o d e , t h e gr ou ndp o i n t . A s e l f - c o n ta i n e d s o u rc e of a l t e r n a t i n g c u r r e n t a nd a b a t t e r y
o p e r a t e d v i b r a t o r s o u r c e e qu ip me nt p r o v i d i n g d i r e c t r e a d i n g s a r e a v a i l -
a b l e .
b ) F a l l - o f - p o t e n t i a l m eth od. The f a l l - o f - p o t e n t i a l m ethod i n v o l v e s a n
u ng ro un de d a l t e r n a t i n g c u r r e n t s o u r c e wh ic h c i r c u l a t e s a m ea su re d
c u r r e n t t o gr ou nd . V ol ta ge r e a d i n g s t a k e n , of t h e c o n n e c t i o n t o
au x i l i a r y g rounds , a l low use o f Ohm's l aw t o de te rmine th e g round
r e s i s t a n c e .
U nd er gr ou nd d i s t r i b u t i o n s ys t e m s
2 .5.15 .1 P ri ma ry power d i s t r i b u t i o n c i r c u i t s i n c e r t a i n a r e a s o n a nd n e a r a er od ro m esm us t b e i n s t a l l e d u nd er gr ou nd . A l th o ug h u n de r gr o un d i n s t a l l a t i o n s c o s t mo re t h a n o v er -
h ea d s y s te m s , r a d i o i n t e r f e r e n c e pr obl em s o r t h e p ro x im i ty of t h e l i g h t i n g f a c i l i t i e s t o
a r e a s o f a i r c r a f t o p e r a t i o n s o f t e n r e q u i r e s t h e u se of u n de rg ro un d d i s t r i b u t i o n s ys te ms .
U nd er gr ou nd c i r c u i t s may be i n s t a l l e d by d i r e c t b u r i a l o r by t h e p u l l - i n m et ho d ( p u l l i n g
t h e c a bl e s t hr ou gh c o nd u it s ). D i r e c t b u r i a l of d i s t r i b u t i o n c i r c u i t s i s u s u a l l y l e s s
c o s t l y t h an i n s t a l l a t i o n i n d u c t s ( p u l l i n m et ho d) , b u t b ec au se of t h e p o o r e r p r o t e c -
t i o n , d i r e c t b u r i a l i s u s u a l l y u se d o n l y f o r s m a l l lo a d s wh ere r e i i a b i i i i y r e q ui r e me n t s
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a r e lo w. M e d i u m v o l ta g e d i r e c t b u r i a l c a b l e s h o u l d b e p r o v id e d w i t h a m e t a l a r m orc o v e r i ng o r s h i e l d f o r p r o t e c t i o n a g a i n s t m e ch a ni ca l i n j u r y . Where c o r r o s i o n r e s i s t a n c e
i s i m p o r t a n t , a rm or ed c a b l e s may r e q u i r e a p l a s t i c o r s yn t h e t i c- r u b b e r j a c k e t o v e r t h e
armor. The u nd er gr ou nd d i s t r i b u t i o n c i r c u i t s us ed f o r ae ro dr om e l i g h t i n g a n d r a d i o
n a vi ga t i on f a c i l i t i e s a r e pu l l - i n c i r c u i t s .
2 . 5 . 15 . 2 D e t a i l s of t h e i n s t a l l a t i o n of u nd er gr ou nd d i s t r i b u t i o n s ys te m s a r e g iv e n i n
Chapter 4 , and c h a r a c t e r i s t i c s of c a b l e s u i t a b l e f o r un de rg ro un d s e r v i c e a r e g i v en i n
Chapter 5.
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EUeTRZGBL CIRCUITS FOR AEBO L I G H T W m W I O I G BT Z O N B I D S
3.1 TYPES OF ELECTRICAL CIRCUITS
3.1.1 E l e c t r i c a l c h a r a c t e r i s t i c s
3.1.1.1 E l e c t r i c a l p ower f o r a e ro dr om e l i g h t i n g a i d s i s a lm os t e n t i r e l y a l t e r n a t i n g
c u r r e n t ( a c ) . (Some c o n t r o l c i r c u i t s a re d i r e c t c u r r e n t ( d c) and en er gy f o r s t a r t i n g
s e c o n da r y p owe r e n g i n e s o r f o r some u n i n t e r r u p t i b l e p owe r s y s te m s i s s t o r e d i n b a t t e r -
i e s . ) T hi s a l t e r n a t i n g c u r r e n t i s u s u a l l y 50 t o 60 h e r t z . Both s e r i e s a nd p a r a l l e l
c i r c u i t s a r e u se d i n t h e s e l i g h t i n g i n s t a l l a t i o n s . Most o f t h e a e ro d ro m e l i g h t s a r ee n e r g i z e d by s e r i e s c i r c u i t s , b u t t h e i nc om in g power i s d i s t r i b u t e d by p a r a l l e l c i r -
c u i t s , a nd some s i n g l e u n i t s o r s h o r t e r c i r c u i t s o f l i g h t s may be e ne r g i z e d by p a r a l l e l
c i r c u i t s . S eq ue nc e- fl as hi ng l i g h t s of a pp r oa c h l i g h t i n g s y st e ms , some f l o o d l i g h t s , a nd
some o b s t a c l e l i g h t s a r e t h e more i m p o rt a nt l i g h t i n g sy s te m s u s i n g p a r a l l e l c i r c u i t s .
3.1 .2 S e r i e s c i r c u i t s
3.1.2.1 The c i r c u i t e l e me n t s o f s e r i e s c i r c u i t s a r e c o nn e ct e d i n a s t r i n g w i th t h e
same c u r r e n t f l o w in g i n e a c h e l em e nt . The c i r c u i t i s o ne c o nt i n uo u s l o o p s t a r t i n g an d
e n d i ng a t t h e i n p u t p ower s o u r c e . I f a f i x e d i n p u t v o l t a g e w ere c o nn e c te d t o t h e l o a d ,
t h e c u r r e n t i n t h e c i r c u i t wou ld v a r y w i t h t h e c o nn ec te d l o a d ; h ow ev er, c o n s t a n t - c u rr e n t
r e g u l a t o r s w i l l m a i n t a i n a c o n s t a n t c u r r e n t i nd ep en de nt o f t h e l o ad o n t h e c i r c u i t .
Thus t h e same cu r r e n t w i l l f l ow i n a l on g c i r c u i t a s i n a s h o r t e r c i r c u i t and w i l l
r e m a i n t h e same e v en i f s ome o f t h e la mp s f a i l . T h i s c o n s t a n t c u r r e n t m ean s t h a t a
s h o r t - c i r c u i t a c r o s s t h e o u t p ut of a c o n s t a n t - c u r r e n t r e g u l a t o r i s a n o -l o ad c o n d i t i o n
a n d a n o p e n - c i r c u i t i s a n o v e r l o a d . I n a s i m p l e d i r e c t - c o n n e c t e d se r i e s c i r c u i t , a lamp
f a i l u r e c a us e s a n o p e n -c i r ui t ; h en ce , i t i t n e c e s s a r y t o p r o v i d e a b y- pa ss d e v i c e , s u c h
as a f u s e d f i l m cu t o u t o r a n i s o l a t i n g t r a n s fo r m er , as p a r t o f e ac h l i g h t i n g f i x t u r e .
I s o l a t i n g t ra n sf o rm e rs a r e p r e f e r r ed f o r a ero dro me l i g h t i n g c i r c u i t s .
3.1.2.2 . Some o f t h e a d v a n t a g e s o f s e r i e s
c i r c u i t s f o r aero drome l i g h t i n g a r e :
a ) a l l lamps a r e o p e r a t i n g a t t h e same c u r r e n t a n d t hu s a t t h e s ame i n t e n -
s i t y . T h i s u n if o rm i n t e n s i t y an d a p pe a ra n ce of t h e l am ps a re h e l p f u l ;
b ) a s in g le - co n du c to r c a b l e o f o ne c o nd u ct o r s i z e an d i n s u l a t i o n v o l t a g e
r a t i n g c an b e u s ed t h ro u gh o ut t h e c i r c u i t ;
c ) i n t e n s i t y c o n t r o l o f t h e l i g h t s ca n b e o b t a in e d o v e r a w i d e r a n g e ;
d ) t h e c i r c u i t may h av e a s i n g l e g ro un d f a u l t a t a ny p o i n t a l o n g t h e
c i r c u i t w i th ou t a f f e c t i n g t h e o p e r a t i o n o f t h e l i g h t s ; a nd
e ) ground f a u l t s a r e e a sy t o l o c a t e .
3 ,1 .2 .3 D i sa d va n ta g es o f s e r i e s l i g h t i n g c i r c u i t s . The m a jo r d i s a d v a n t a g e s o f
s e r i e s c i r c u i t s when us ed f o r l i g h t i n g a r e :
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a ) i n s t a l l a t i o n c o s t s a r e h ig h - t h e c o n st a n t - c u r re n t r e g u l a t o r a nd t h e
i s o l a t i n g t r a n s f o r m e r s o r b y-pass d e v ic e s add a p p r e ci a b l y t o t h i s c o s t ;
b ) p oo r e f f i c i e n c y , p r i m a r i l y o f t h e m o vi ng -c oi l t y p e c o n s t a n t - c u r r e n t
r e g u l a t o r , i n u s e of e l e c t r i c a l power;
c ) a l l com ponents - c a b l e , i s o l a t i n g t r a n s f o r m e r s an d lamp s o c k e t s - must
be i n s u l a t e d f o r f u l l vo l ta g e i f i s o l a t i n g t r a ns f or m er s a r e n o t u sed ;
d ) a n op en -- ci rc ui t f a u l t anywhere i n t h e c i r c u i t makes t h e e n t i r e c i r c u i t
i n o p e r a t i v e a n d p o s s i b l y may damage t h e c a b l e i n s u l a t i o n o r t h e
c o n s t a n t- c u r r e n t r e g u l a t o r ; a nd
e ) l o c a t i o n of f a u l t s , e s p e c i a l l y o p e n- c i rc u i t f a u l t s , may b e d i f f i c u l t .
3.1.3 P a r a l l e l c i r c u i t s
3.1 .3.1 The c i r c u i t e le m en t s of p a r a l l e l ( m u l t i p l e ) c i r c u i t s a r e c o nn e ct e d i n
p a r a l l e l a c r o s s t h e c o n d uc to r s t o w hi ch t h e i n p u t v o l t a g e i s a p p l i e d . I n t h e o r y t h e
s a m e v o l t a g e i s a p p l i e d t o ea c h l i g h t ; h ow ev er , t h e c u r r e n t t h ro u gh t h e c o n d u c t o r s
c a u s e s a d e c r e a s e i n v o l t a g e ( l i n e d r o p ) w hi ch f o r l o n g e r c i r c u i t s may r e d u c e a p p r ec i -
a b l y t h e v o l ta g e t o , and c on se qu en tl y t h e i n t e n s i t y o f , t h e l i g h t s a t t h e f a r en d of t h e
c i r c u i t . I n d i s t r i b u t i o n c i r c u i t s w he re t h e v o l t a g e may be h i g h and t h e c u r r e n t l ow,
t h e v o l t ag e d ro p i n t h e l i n e s i s l e s s i mp or ta nt , and p a r a l l e l c i r c u i t s a r e o f t e n us ed
f o r s uc h c i r c u i t s . I f i n t e n s i t y c o n t r o l o f t h e l i g h t s i s r e q u i r e d , t a p pe d t r a n s f o r m e r s
o f i n d u c t i o n - v o l t a g e r e g u l a t o r s may be u s ed , b u t t h e s e i n c r e a s e t h e c o s t of t h e i n s t a l l -
a t i o n and r e du c e t h e e f f i c i e n c y of t h e c i r c u i t .
3.1.3.2 Some of t h e adv ant age s o f
p a r a l l e l c i r c u i t s f o r a erodrome l i g h t i n g ar e :
a ) lo we r c o s t of t h e i n s t a l l a t i o n , e s p e c ia l l y i f v ~ l t a g e e g u l a t io n an di n t e n s i t y c o n t r o l a r e n o t r e qu i re d ;
b ) more e f f i c i e n t u t i l i z a t i o n of e l e c t r i c a l power;
c ) e a sy t o add t o o r r ed uc e a n e x i s t i n g c i r c u i t ;
d ) t h e c i r c u i t s a r e more f a m i l i a r t o most p e o pl e ;
e ) c a b l e f a u l t s , e s p ec i . a l l y o p e n- c i rc u i t f a u l t s , may be e a s i e r t o l o c a t e ;
f ) a n o p en - ci r cu i t may n o t d i s a b l e t h e e n t i r e c i r c u i t ; a nd
g ) t h e s e c i r c u i t s d o n o t n e ed b y - p as s d e v i c e s an d may n o t n ee d i s o l a t i n gt r a n s f o r m e r s .
3 .1 .3 .3 D i s ad v a n ta g e s of p a r a l l e l l i g h t i n g c i r c u i t s . Some o f t h e m a j o r d i s a d v a n t -
a g es o f p a r a l l e l c i r c u i t s f o r aerodro me l i g h t i n g a r e :
a ) t h e i n t e n s i t y of t h e l i g h t s de c re a s es w i th l i n e d ro p a l o ng t h e c i r c u i t .
Th i s may be mis i n t e r p r e t ed i f i t i s n o t i c e a bl e i n a p a t t e r n o f l i g h t s ;
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b ) two c o n du c to r s a r e r e q u i r e d a l o n g t h e c om pl et e c i r c u i t , a nd l a r g e r
c o n d u c t or s may b e ne ed ed t o r e d u c e t h e l i n e v o l t a g e d r o p ;
c ) lam p f i l a m e n t s a r e u s u a l l y l o n g e r wh ic h may r e q u i r e l a r g e r o p t i c s a n d
l a r g e r l i g h t E i x tu r e s;
d ) i n t e n s i t y c o n t ro l , e s p e c i a l l y a t t h e lo we r i n t e n s i t i e s , i s m o r e d i f f i -
c u l t t o f u r n i s h a c c u r a t e l y , o r t h e e qu ip me nt c o s t a dd s a p p r ec i a b ly t o
t h e i n s t a l l a t i o n c os t;
e ) a s i n g l e gr ou nd f a u l t on t h e hi g h - v o lt a g e f e e d e r w i l l d i s a b l e t h e
c i r c u i t s ; an d
f ) ground f a u l t s a r e d i f f i c u l t t o l oc a te .
C om parison o f s e r i e s and p a r a l l e l l i g h t i n g c i r c u i t s
3.1.4.1 O ft en ac c e p t a b l e l i g h t i n g c an be p ro v id ed by e i t h e r s e r i e s o r p a r a l l e l
c i r c u i t s . S e r i e s c i r c u i t s a r e u s u a l l y us ed f o r aer odr om e l i g h t i n g s ys te ms wh er e t h e
p a t t e r n p r o v i d e s g u i da n ce i n f o r m a t i o n be ca u se o f t h e more un i fo r m i n t e n s i t y o f t h e
l i g h t s a nd b e t t e r i n t e n s i t y c o n t r o l . S uc h s y s te m s i n c l u d e m os t runway an d t a x iw a y
l i g h t s and most s te ad y -b u rn in g l i g h t s o f a pp ro ac h l i g h t i n g s y st em s . P a r a l l e l c i r c u i t s
a r e u s e d f o r most a r e a i l l u m i n a t i o n , i n d i v i d u a l o r s m a l l num bers o f v i s u a l a i d s , a nd
power d i s t r i b u t i o n . Aerodrome l i g h t i n g s y st em s u s u a l l y u s i n g p a r a l l e l c i r c u i t s a r e
a p ro n f l o o d l i g h t i n g , o t h e r a pr on l i g h t s , s e qu e nc e- f la s hi ng l i g h t s , s p e c i a l p u rp o se
v i s u a l a i d s s uc h a s b e ac on s a nd wind d i r e c t i o n i n d i c a t o r s , some o b s t a c l e l i g h t s a nd
e l e c t r i c a l d i s t r i b u t i o n c i r c u i t s .
3.2 S E R I E S C I R C U I T R Y FO R AERODROME L I G H T I N G
F a c t o r s t o be c o n s i d e r e d
3.2.1.1 If a s e r i e s c i r c u i t i s t o be u s e d , c e r t a i n o p t i o n s o n t h e e qu ip me nt t o b e
used should be eva lua ted . Often when one cho ice i s made i t r e du c e s t h e o p t i o n s of o t h e r
equipment. F i r s t , t h e c o mp le te c i r c u i t s h ou ld be a n al y s ed f o r c r i t i c a l pe rf or ma nc e,
r e l i a b i l i t y , economy of i n s t a l l a t i o n s an d o p e r a t i o n s , e a s e of m a i nt e n an c e , a nd how t h e
s e v e r a l t y p e s o f equ ip me nt a r e i n t e r r e l a t e d . Some o p t i o n a l f a c t o r s a r e t h e f o l l o w i n g
i t e m s .
3 .2 .1 .2 Choice of cu r r en t . Equ ipment deve lopmen t ha s l i mi t e d th e av a i l a b l e op t io ns
of c u r r e n t t o be u se d i n a p a r t i c u l a r s e r i e s c i r c u i t . Most aer od rom e l i g h t i n g s e r i e s
c i r c u i t s a r e e i t h e r 6.6 o r 20 am peres a t r a t e d f u l l i n t e n s i t y , a l th o ug h o t h e r c u r r e n t sa r e so m et im es u se d. The l i n e power l o s s f o r a f i x e d c a b l e c o n d u ct o r a nd l e n g t h f o r 6 .6
a m p e r e c i r c u i t s i s a bo ut o n e n i n t h t h a t f o r 20 ampere c i r c u i t s . E i t h e r v a l u e o f c u r r e n t
c an be c a r r i e d i n 5 0 00 v o l t i n s u l a t i o n c a b l e by c o n d u c t o r s of 4 mm d i a m e t e r w i t h o u t
e x c e s s i v e t e m pe r at u r e r i s e . The l o a d o n t h e r e g u l a t o r of s e r i e s c i r c u i t s , s h o u l d be a t
l e a s t o ne -h al f o f i t s r a t e d c a p a c i t y . 6.6 a m pe re c i r c u i t s a r e commonly u s e d f o r l o ng
c i r c u i t s w i t h s ma ll er e l e c t r i c a l l o a d s , and 20 aa pe re c i r c u i t s a r e u se d f o r l a r g e r l o a d s
a nd s h o r t e r c a b l e l e n g t h s ( s e e p ar a g ra p h 3 .2 .1 .4 f o r r e g u l a t o r c a p a c i t i e s . ) Runway e dg e
l i g h t s a nd t ax iw ay e dg e l i g h t s a r e u s u a l l y 6 ,6 a olpere c i r c u i t s , a nd a pp r o ac h l i g h t s a n d
rouchdown zone l i g h t s a r e o f t e n 20 a m p e r e c i r c u i t s , Kunway c e n t r e l i n e a n d t a x i w a y
c e n t r e l i n e l i g h t s may be e x t h e r 6.6 a n p e r e o r 20 ampere c i r c u i ~ s , Koce t h a t &he c l r -
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c u i t c u r r e n t i s n o t n e c e s s a r i l y d e t er mi n ed by t h e c u r r e n t of t h e l am ps i n t h e f i x t u r e s .
F o r ex am pl e by s e l e c t i n g t h e i s o l a t i n g t r a n s fo r m e r s p r o p e r l y , 6.6 ampere lamps can be
used on 20 ampere c i r c u i t s and 20 ampere lamps on 6.6 a mp ere c i r c u i t s o r c o m b i na t i on s of
lamp c u r r e n t s c an be us ed on e i t h e r c i r c u i t .
3.2.1.3 The p r e f e r r e d a r ra ngem e n t f o r a er od rom e l i g h t -
i n g c i r c u i t s i s a number of h i g h v o l t a g e s e r i e s c i r c u i t l o o p s w i t h a s e r i e s i s o l a t i n g
t ra n sf or me r f o r e a ch f i t t i n g , and e ac h c i r c u i t f e d f ro m a n e l e c t r i c a l s u pp l y s u b s t a t i o n
ad ja ce nt t o th e runway end . One su bs ta t i on pe r runway end i s p r e f e r r e d f o r a l l aero-
dromes.
a ) 8.2 of Annex 1 4 s p e c i f i e s t h a t f o r a pr e c i s i o n a pp roa c h r unwa y t he
e l e c t r i c a l c i r c u i t s be de si gn ed s o t h a t t h e f a i l u r e of o n e c i r c u i t w i l l
n o t l e a v e t h e p i l o t w i t ho u t v i s u a l g u id an ce a nd w i l l n ot r e s u l t i n a
m i s l e a d i n g p a t t e r n .
b Every approach and runway l ig h t -
i n g sy s te m s h o u l d b e i n t e r l e a v e d o v e r a t l e a s t t wo c i r c u i t s . Exam ples
of c i r c u i t i n t e r l e a v i n g t o i mp ro ve i n t e g r i t y a r e shown i n F i g u r e s 3-1 t o3-7. E ach c i r c u i t i n a n i n t e r l e a v e d s e r v i c e s h o u l d e x t e n d t h r o u g h o u t
t h e w ho le of t h a t s e r v i c e an d b e s o a r ra n g e d t h a t a ba lanced symmetr ica l
l i g h t i n g p a t t e r n r e m aj n s i n t h e e v e n t of f a i l u r e of o n e o r more of t h e
c i r c u i t s . T hr es ho ld l i g h t s a r e u s u a l l y o n s e p a r a t e c i r c u i t s . Runway
c e n t r e l i n e l i g h t s must b e i n t e r l e a v e d i n a way t h a t w i l l n o t d e s t r o y
t h e c o lo u r c o di ng of t h e s e l i g h t s . S e ct i o ns of t h e c e n t r e l i n e s ys te m
c o n s i s t i n g of w h i t e l i g h t s o n l y an d o f r e d l i g h t s o n l y may be i n t e r -
leave d a s shown on Figure 3-5a. Annex 1 4 r e q u i r e s t h e c e n t r e l i n e
l i g h t s i n t h e s e c t i o n o f t h e runway f ro m t h e p o i n t 900 m f rom the runway
end (o r from th e midpoin t of th e runway f o r runways l e s s t ha n 1 800 m i n
l e n g t h ) t o t h e p o i n t 3 00 m f rom t h e runway e nd be a l t e r n a t e l y va r i a b l e
w h it e and r e d l i g h t s e x c e p t t h a t f o r runway c e n t r e l i n e l i g h t s s pa ce d a t
7 .5 n a l t e r n a t e p a i r of v a r i a b l e w h i te and r e d l i g h t s a r e r e q u i r e d .Exam ples of c i r c u i t i n t e r l e a v i ng wh ic h w i l l m a i n t a i n t h e r e q u i r e d c o l o u r
coding a r e shown i n F ig ure s 3-5b and 3-5c. When one c i r c u i t f a i l s where
t h e p a t t e r n o f l i g h t s an d i n t e r l e a v i n g a r e a s shown i n F i g u r e 3-5c, a
p a t t e r n of a l t e r n a t i n g r ed an d w h i t e l i g h t s u n i fo r m ly s p a c ed a t tw ice
t h e n or ma l i n t e r v a l w i l l show. This sp ac in g i s t h e same a s t h a t o f t h e
a l l w hi te and a l l r e d s e ct i o n s when one c i r c u i t f a i l s . With t h e p a t t e r n
o f l i g h t s a nd i n t e r l e a v i n g shown i n F i gu r e 3-5b, t he s pa c i ng would be
a l t e r n a t e l y t h r e e t i m es t h e n orm al i n t e r v a l a nd t h e n t h e n o rm al
i n t e r v a l .
c ) V i s u a l a p pr oa c h s l o p e i n d i c a t o r s ys t em s . V i s u a l a p p ro a c h s l o p e i n d i c a -
t o r sys tems should have two c i r c u i t s pe r runway end . When a v i su a l
a pp ro ac h s l o p e i n d i c a t o r s y st e m i s a VASIS, 3-BAR VASIS, o r T-VASIS,power t o a l l l i g h t u n i t s on on e s i d e of t h e r unway s h o u l d b e s u p p l i e d by
t h e same c i r c u i t . T hi s a rr an ge me nt e n s u r e s t h a t s h o u ld o ne c i r c u i t f a i l
a c om pl e te pa t t e r n w i l l be r e t a i ne d on t h e o t h e r s i d e of t h e runw ay .
When ap p ro a ch s l o p e i n d i c a t o r s a r e i n s t a l l e d on o n l y o ne s i d e o f t h e
runway a s w i t h t h e PAPI, t h e AVASIS, t h e 3-BAR AVASIS, an d t h e AT-VASIS,
p a r t o f t h e l am ps i n e a ch L ig h t u n i t s h o ul d be c o nn e ct ed t o o n e c i r c u i t
and t h e r em ai nd er t o t h e o t h e r c i r c u i t i n o r d er t o m a in t ai n t h e
i n t e g r i t y of t h e p a t t e r n , b u t w i t h r e d u c e d i n t e n s i t y . V i s ua l a pp r oa c h
s l op e i nd i c a t o i s y st e m s s hou l d be de e ne r g i z e d when a m i s l e ad i n g s i g n a l
r e s u l t s fro m rh e f a i l u r e of a L i g h t u n i t .
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d Taxiway l i g h t i n g s h o ul d b e d e s ig n e d f o r s e r i e s
c i r c u i t s . Taxiway c e n t r e l i n e l i g h t i n g c i r c u i t s s h ou ld b e i n t er l e a v e d
a s shown i n F i g u re 3 -5a o n t h o s e p a r t s o f t h e t a x i w a y s y s t e m t h a t a r e
u s e d i n C a te g or y 111 c o n d i t i o n s , b u t f o r e co no mi c r e a s o n s a s i n g l e
c i r c u i t may b e u s ed f o r o t h e r t ax i wa ys . T axiw ay l i g h t i n g s h o u l d b e
c i r c u i t e d t o p e r mi t s e l e c t i v e l i g h t i n g of s eg me nt s of t h e s y s te m t o
p r o vi d e r o u t e g ui da nc e t o p i l o t s . Th i s c a pa b i l i t y may be ob ta i ned by
u s i n g a n i n d i v i d u a l c o n s t an t - c u r re n t r e g u l a t o r f o r e a c h s eg m en t o r by
c on n ec ti n g s e v e r a l s eg me nt s t o a s i n g l e r e g u l a t o r an d u s i n g s e l e c t o r
r e l a y s , e i t h e r i n th e f i e l d o r a t t h e r eg u l a t or , t o s h o r t - c i r c u i t t ho s e
s eg me nt s w hi ch a r e n o t p a r t of t h e r o u t e . Note t h a t t h e v o l t a g e r a t i n g
o f t h e s e l e c t o r r e l a y s must be h i g h e r t h an t h e o p e n - c i r c u i t v o l t a g e of
t h e r e g u l a t o r . S e l e c t i v e s w i t c h i n g may b e o b t a i n e d i n s e v e r a l w ays.
Among t h e s e ar e :
1) t h e u s e of a c o n t r o l s w i t c h f o r e a c h s eg me nt . The p r e f e r r e d
l o c a t i o n of s u c h s w i t c h es i s o n a f a c s i m i l e d i ag r am o n t h e c o n t r o l
p a n e l i n t h e c o n t r o l t o we r w i t h e a c h s w i t c h l o c a t e d o n t h e s eg me nt
which i t c o n t r o l s ;
2 ) i n t e r c o n n e c t i n g t h e c o n t r o l s w hi ch e n e r g i z e t h e r e g u l a t o r s o r
s e l e c t o r r e l a y s o t h a t a c t u a t i n g a s i n g l e s w i tc h w i l l c au s e a l l
s eg me nt s on a d e s i g n a t e d r o u t e t o b e l i g h t e d ; a nd
3 ) u s i n g a m in i co m pu t er programmed t o l i g h t t h e o pti mu m r o u t e a f t e r t h e
o p e r a t o r d e s i g n a t e s t h e r unway e x i t t o be us ed a nd t h e d e s t i n a t i o n
of t h e a i r c r a f t .
e ) S t o p b a r s . S to p b a r s mu st b e c o n t r o l l e d i n d e p e n d e n t l y o f e a c h o t h e r a n d
of t h e t ax i wa y l i g h t s . The e l e c t r i c a l c i r c u i t s s h ou l d be d e s i gn e d s o
t h a t a l l of t h e l i g h t s of a s t o p b a r w i l l n o t f a i l a t t h e same t im e.
The l i g h t s o f a s t o p b a r s h ou l d b e i n t e r l e a v e d . They may be s u p p l i e d b ytwo s e p a r a t e c i r c u i t s o r f r om two common c i r c u i t s w i t h c o n t r o l r e l a y s
l o c a te d a d j a c e n t t o t h e s t o p ba r. S top ba r s may be connec ted i n t o
i n t e r l e a v e d runway o r t a x iw a y l i g h t i n g s y st em s w i t h e a c h s t o p b a r
c o n t r o l l e d by r e l a y s wh ic h s h o r t - c i r c u i t t h e l i g h t s of t h e s t o p ba r when
i t i s d e s i r e d t o d ee n er g i ze t h e b a r. I n o r d e r t o r ed u ce t h e v o l t a g e
r e qu i r em e n ts o f t h e s e r e l a y s , l i g h t s of t h e s t o p b a r s h o u l d be c o nn e ct ed
i n t o a runway o r t a xi wa y l i g h t i n g c i r c u i t t hr o ug h an i s o l a t i n g
t r an s f or m e r of s u i t a b l e c a pa c i t y w i t h t h e s h o r t - c i r c u i t i n g r e l a y
c o nn e ct e d a c r o s s t h e s e co n d ar y o f t h e i s o l a t i n g t r a n s f o r m e r . The
a p p l i c a b l e r unway o r t a x i wa y l i g h t i n g c i r c u i t m us t b e e n e r g i z e d w hen ev er
t h e u s e of a s t o p b a r i s r e q u i r ed . The r e l a y s c o n t r o l l i n g a s t o p b a r
m ust b e s o c o nn e c te d t h a t t h e a p p l i c a t i o n o f c o n t r o l po we r i s r e q u i r e d
t o t u r n t h e s t o p b ar o f f . Thus t h e s t o p b a r w i l l be l i g h t e d i f t h ec o n t r o l c i r c u i t s h ou ld f a i l .
f ) G ro un din g, A l l t h e e qu ip men t i n t h e c o n t r o l / d i s t r i b u t i o n c e n t r e s h o ul d
be bonded t o ea r th . A g ro un d w i r e ( c o u n t e r p o i s e ) s h o u l d a l s o b e r u n
f ro m t h e d i s t r i b u t i o n c e n tr e s w it h t h e s e r i e s c i r c u i t c a b l e s . The
s ec on da ry s i d e of a l l i s o l a t i n g t ra n s fo r m er s and t h e s u p p o r t s of a l l
e l e v a t e d l i g h t s s ho u l d b e c o nn e ct ed t o t h i s w i r e . The gr o un d w i r e
s h o u l d be p o s i t i o n e d a bo ve t h e c i r c u i t c a b l e s i n a c o n d u i t nearer t h e
s u r f a ce o r i n t h e s ame r r e n c l ~ or l e s s t h an 10 c m a b o v e t h e cop, cable. .
U s u a l l y u n i n s u l a t e d c o n d u c t o rs a r e u se d a s g r ou n d w i r e s .
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0 CIRCUIT 1
Q) CIRCUIT 2
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0 CIRCUIT 3
@ CIRCUIT 4
F i g u r e 3-2, S u pp le me nt ar y l i g h t i n g t o e x pa nd a p r e c i s i o n a p p ro ac h b i g h t i n g
s y s t e m t y p e A ( sys tem wPth d i s t a n c e coded c e n t r e l i n e ) t o a p r e c i s i o n
approach ca tegory I1 an d 111 l i g h t i n g s y st e m
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5-3 0 Aerodrome Design Manual
RUNWAY THRESHOLD
0 CIl iCh i iT i
0 C I R C U I T 2
O P T I O N A . I N T E R L E A V I N G BY A L T E R N A T I N G B A R R E T T E S
-r ' l gu re 3-3. P r e c i s i o n approach lighting s y s t e m t y p e B
( s y s t e m w i t h b a r r e t t e c e n t r e l i n e )
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0 CIRCUIT 16 CIRCUIT 2
OPTION B. INTERLEAVING BY ALTERNATING LIGHTS IN EACH
BARRETTE TO FROVIDE S I M I M R APPEARANCE IN EITH
SINGLE-CIRCUIT OPERATION
Figure 3-3, P r e c i s i o n a p p r o a c h l i g h t i n g s ys te m t y pe B( sys tem w i t h b a r r e t t e c e n t re l i n e )
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RUNWAY THRESHOLD
0 CIRCUIT 1.
$ CIRCUIT 2
OPTION C. INTERLEAVING BY ALTERNATING LIG HTS IN EACH
BARRETTE WITH ALL S T AT IO N A L I K E I N ANY
OPERATING CI RC UI T MODE
F i g u r e 3 - 3 . P r e c i s i o n a p p r o a c h iighting s y s t e m t y p e B
( s y s t e m w i i h b a r r e t c e c e n t r e iinej
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RUNWAY THRESHOLD RUNWAY THRESHOLD
e
PART OF CENTRE LlNE LIGHTS
Q CIRCUIT 1
CIRCUIT 2
OF PRECISION APPROACI-I
LIGHTING SYSTEM TYPE B
PART OF CENTRE LlNE LIGHTS
OF PRECISION APPROACH
0 CIRCUIT l LIGHTING SYSTEM TYPE B
@ CIRCUIT 2
OPTION A. INTERLEAVING BY ALTERNATlNG BARRETTES OPTION B. INTERLEAVING BY ALTERNATING LIGHTS IN EACH
BARRETTE TO PROVIDE SIMILAR APPEARANCE FOR
EITHER SINGLE-CIRCUIT OPERATION
Figure 3-4. Supplementary lighting to expand a precision approach lighting
system type B (system with barrette centre line) to a precision approach
category 11 and I11 lighting system
(Supplementary lighting for a system with distance coded centre line
is shown in Figure 3-2.)
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A . I N T ER L E A V IN G I N S E C T I O N S
I N W HI CH ALL L I G H T S A R E
O F T HE SAME COLOUR
Q W H I T E L I G H T
C I R C U I T 1
C I R C U I T 2
C I R C U I T l
B . I N T E RL E A V IN G I N S E C T I O N S
C O N S I S T I N G O F A L T E R NA T I N G RE D
AND W H I TE L I G H T S F O R L I G H T
S P A C I N G S O F 15 AND 30 METERS
0 W H I T E L I G H T
C I R C U I T I.
@ 'WfiITE EIZHT
C I R C U I T 2
C I R C U I T l
C . I N T E RL E A V IN G I N S E C T I O N S
CO NSI STI NG O F ALTERNATE TWO RE D
AND TWO WHITE LI GH TS FOR LI GH T
S P A C I N G S O F 7.5 METERS
Figure 3-5. Runway or taxiway c en tr e L ~ n e rg ht in g on two interleaved circuits
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Part 5, - Electrical Svstems 5-35
0 CIRCUIT 1
@ CIRCUIT 2
F i g u r e 3 -6 . Runway edge Lights on two ~ n t e r l e a v e d eries circuits
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RUNWAY
NOTE: When used i n co n ju nc t i o n w i t h Type A p r e c i s i o n a p p r o a c h l i g h t i n gsys terns each barret te s h a u l d hav e f o u r l ights .
F k ~ u r e3 - 7 , Touchdown zone L i g h t s o i l t w ~n t e r l e a v e c j s e r i e s c i r c u i t s
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3.2.1.4 The e l e c t r i c a l pow er f o r m o st a e r od r om e g r o un d
l i g h t i n g c i r c u i t s i s s u p p l i e d by c o n st a n t- c u rr e n t ( s e r i e s c i r c u i t ) r e g u l a t o r s . T he se
r e g u l a t o r s a r e d e si g ne d t o p ro du ce a c o n s t a n t- c u r r e n t o u t p u t i n d ep e n de n t o f v a r i a t i o n s
i n t h e c i r c u i t l o a d a nd i n t h e v o l t a g e of t h e power s o ur ce . They a r e a l s o d es i gn e d t o
p r o v i d e tw o o r m ore o u t p u t c u r r e n t s when dim ming of t h e l i g h t s i s r e q u i r e d . Some ty p e s
of c o n st a nt - c ur r e nt r e g u l a t o r s u s e d f o r a er od ro me l i g h t i n g a r e a s f o l l o w s .
a ) Moving c o i l r e g u l a t o r s . Moving c o i l r e g u l a t o r s h a v e b ee n u s e d f o r many
y e a r s t o su pp ly power t o s e r i e s l i g h t i n g c i r c u i t s . T h is t y p e r e g u l a t o r
h a s s e p a r a t e p r i m a ry a n d s ec o nd a ry c o i l s w hi ch a r e f r e e t o move w i t h
r e s p e c t t o e a ch o t h e r , t h u s v a r y i n g t h e m ag n e ti c l e a k a g e r e a c t a n c e o f
t h e i n p u t a nd o u t p u t c i r c u i t s . T hi s r e a c t an c e a u t o m a t i c a l l y a d j u s t s
i t s e l f t o a va lu e which , when added t o t h e l oa d impedance , pe rm i t s a
c o n s t a n t c u r r e n t t o fl ow . The d e s i r e d o u t p u t c u r r e n t s e t s up a f o r c e o f
r e p u l s i o n w hi ch f l o a t s t h e moving c o i l i n t h e p o s i t i o n w h ic h pr o du c es
t h i s c u r re n t . A s t a t e o f m e ch a ni ca l e q u i l i b r i u m i s a t t a i n e d s u ch t h a t
t h e f o r c e of r e p u l s i o n e x a c t l y b a l a n c e s t h e w e ig h t o f t h e m oving c o i l .
Any c h an ge i n l o a d o r i n p u t v o l t a g e i s immed ia te ly cou n te rac ted by a
movement o f t h e f l o a t i n g c o i l t o r e s t o r e t h e m ec ha ni ca l e l e c t r i c a lb a la nc e . I n t e n s i t y c o n t r o l i s o b t a i n e d t h r o u gh t h e u s e o f a t a p p ed
t r a n s f o r m e r a c r o s s t h e o u t p u t of t h e r e g u l a t o r . Th e m ai n d i s a d v a n t a g e s
o f m oving c o i l r e g u l a t o r s a r e t h e m e c ha n i ca l movement o f t h e c o i l s a n d
t h e low power f a c t o r s f o r l o a d s l e s s t h a n r a t e d lo a d . F o r a l oad o f 50
p e r c e n t o f t h e r a t e d l o a d , t h e power f a c t o r may be 75 p e r c e n t o r l e s s .
I n a d d i t i o n some moving c o i l r e g u l a t o r s m ust b e p r e c i s e l y l e v e l l e d a nd
i s o l a t e d f ro m v i b r a t i o n .
b ) M o n oc y cl ic s q u a r e r e g u l a t o r s . One s t a t i c t y p e ( n o m oving p a r t s )
c o n st a n t- c ur r e nt r e g u l a t o r f o r s e r i e s c i r c u i t s i s t h e m o n o c yc l i c s q u a r e
r e g u l a t o r . The c u r r e n t r e g u l a t i n g n et w or k u s u a l l y c o n s i s t s of t wo
i n d u c t i v e an d tw o c o n de n s iv e r e a c t o r s , e a c h o f e q u a l r e a c t a n c e
( r e s o n a n ce ) a t t h e p ower f r e q u e n cy , a rr a ng e d i n a b r id g e t y p e c i r c u i t .Wi th such a ne twork , t h e seconda ry cu r r en t i s indep enden t of t h e imped-
a n c e o f t h e l o a d . I n t e n s i t y c o n t r o l c a n b e p r o vi d e d by a t a p p e d i n p u t
o r o u t p u t t r a n s f o rm e r o r by c o n t i n u o u s ly v a r i a b l e i n p u t t r a n s f o r m e r.
The a d v a n t a g es o f t h i s t y p e o f r e g u l a t o r a r e n o m ov in g p a r t s a nd h i g h
p ow er f a c t o r . The d i s a d v a n t a g e s a r e l a c k o f co m pe n sa t io n f o r v a r i a t i o n s
i n i n p u t v o l t a g e a nd a d v er s e e f f e c t s o n t h e r e g u l a t i o n c a u se d by l o a d s
w hi ch c au s e h i g h ha rm o ni c f r e q u e n c i e s i n t h e r e s o n a n t c i r c u i t , s u ch a s
o p e n - c i rc u i t e d s e c o n d a r i e s o f s e r i e s i s o l a t i n g t r a n s f o r m e r s a nd g a se o us -
vapour lamps.
c ) C om pe ns at io n s t a t i c - t y p e r e g u l a t o r s . By s e n s i n g t h e s e co n da ry c u r r e n t
f rom th e re gu la to r , ad jus tmen t may be made i n th e monocyc l i c squa r e o r
i n t h e c u r r e n t - r e g u l a t i n g n et wo rk t o c om pe ns at e f o r p ri m a r y v o l t a g e
v a r i a t i o n s a nd f o r ha rm on ic f r e q u e n c i e s c a u s ed by o p e n - c i r c u i t e d s ec on d-
a r i e s o f i s o l a t i n g t r a n s f o r m e r s . T h i s c o mp e ns a ti o n p r o v i d e s i mp ro ve d
current r e g u l a t i o n an d p r e v e n t s s h o r t e n i n g of lamp l i f e f ro m a bo ve r a t e d
s e c o n d a r y c u r r e n t .
d ) S o l i d s t a t e c o n t r c l c o n st a n t- c u rr e n t r e g u l a t o r s . These r e g u l a t o r s u s e
a c s o l i d s t a t e c i r c u i t s f o r c o n t r o l l i n g t h e t r an s fo r me r l ea k ag e r e ac t -
a n c e. T h is t e c h n i q ue p e r m it s t h e u s e of l ow c o n t r o l l e v e l s t o o b t a i n
c o n st a nt c u r r e n t fr om r e g u l at o r s w it h t h e e l e c t r i c a l c h a r a c t e r i s t i c s of
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c o n st a n t v o l t a g e, s e r i e s - re s o n a n t c i r c u i t s . These s o l i d s t a t e c o n t r o l s
p r o v i d e f a s t r es p o n s e , h i g h power f a c t o r , co mp ac t r e g u l a t o r s w i t h e a s y
m a in t en a nc e o f t h e r e g u l a t o r c o n t r o l s .
3 .2 .1 .5 Cons tan t -cu r ren t
r e g u l a t o r s s u p p ly i n g power t o a er od ro me l i g h t i n g c i r c u i t s s h o ul d ha ve t h e f o l l o w i n g
c a p a b i l i t i e s :
a ) m a i n t a i n a c o n s t a n t -c u r r e n t o u t p u t w i t h i n k 2 p e r c e n t f o r a n y l o ad f r om
o ne -h alf t o f u l l l o a d w i t h up t o 30 p e r c e n t o f i s o l a t i n g t r a n s f o rm e r s
h a v i n g o p e n - c i r c u i t s e c o n d a r i e S ;
b ) i n d i c a t e a gr ou nd in g f a u l t on t h e c i r c u t t w h i le p e rm i t t i n g t h e c i r c u i t
t o o p e r a t e n o r ma l ly when a s i n g l e g ro un d f a u l t p r e v a i l s ;
c ) h av e a h ig h d e g r e e o f r e l i a b i l i t y an d t h e r e f o r e h av e n o m oving p a r t s ;
d ) i n c o r p o r a t e a n o p e n - c i r c u it d e v i c e w hi ch l o c k s o u t t h e p r i ma r y v o l t a g e
w i t h i n t wo s ec on ds a nd r e q u i r e s r e s e t t i n g o f t h e r e g u l a t o r ;
e ) r es po nd t o c i r c u i t c ha ng es w i t h i n 1 5 c y c l e s ;
f ) i n co r p or a t e a s e c u r i t y d e vi ce t h a t s e t s t h e r e g u la t o r o u t o f s e r v i c e o r
a s s u r e s a r e d u c t i o n o f t h e c u r r e n t i n e a s e of a n o v e r c u r r e n t ;
g ) p r o v id e t h e r e q u i r e d number o f i n t e n s i t y s e t t i n g s o r a c o n t i n u o us l y
v a r i a b l e c o n t r o l a s r e qu i r ed . The r e g u l a t o r s h o u ld b e d e s i g n e d s o t h a t
t h e i n t e n s i t y s e t t i n g c an be c ha ng ed w i t ho u t d e e n e r g i z in g t h e r e g u l a t o r ;
h ) e l e c t r i c a l l y i s o l a t e t h e pr im ar y power c i r c u i t fr om t h e s e co nd ar y l i g h t -
i n g c i r c u i t ; and
i) o p e r a t e c o n t i n u o u s ly a t f u l l l o a d i n a mb ie nt t e m p e r a t u re s b e tw ee n -40°C
and +55"C and r e l a t i v e humid i ty be tween 10 and 100 pe r c en t and a t
a l t i t u d e s up t o 2 000 m.
3 .2 .1 .6 R a t i n g c h a r a c t e r i s t i c s o f c o n s t a n t - cu r r e n t r e g u l a t o r s . The f o l l o w i n g a r e
e xa mp le s of r a t i n g c h a r a c t e r i s t i c s o f c o n s t a nt - cu r r en t r e g u l a t o r s w hic h a r e a v a i l a b l e :
Power . Output (sec onda ry) lo ad s be tween 4 a nd 7 0 k i l o w a t t s . Many s i z e sa )i n t h i s r an ge a r e a v a i la b l e .
b 6 .6 and 20 amperes a r e most common. Un it ss u p p l y i n g 6.6 a mp er es f o r l o a d s up t o 3 0 k i l o w a t t s a n d 20 am p er e s f o r
l o a d s o f 1 0 k i l o w a t t s a nd more a r e o f t e n u se d .
c ) F requency . A s r e q u i r e d by t h e f r eq u e n c y of t h e p r i m ar y p o we r , u s u a l l y
5 0 o r 60 h e r t z .
d Ra ted p r imary vo l t ag es be tween 120 and 12 000 v o l t sh av e b ee n u se d. P r im a ry v o l t a g e s of 240 v o l t s f o r s i z e s u p t o 30
k i l o w a t t s a n 4 2 400 v o l t s f o r s i z e s of i O t o 7 0 k i l o w a t t s a r e us ed by
one S t a t e , O the r p r imary vo l t ag es may a l s o be u sed .
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P a r t 5,- E l e c t r i c a l Svstem s 5-39
3.2.1.7 Most a er od ro me l i g h t i n g c i r c u i t s u s e i s o l a t i n g
t r a ns f o rm e r s t o p ro v id e c o n t in u i t y of t h e s e r i e s c i r c u i t s o t h a t f a i l u r e o f a lamp do es
n o t make a n o p e n - c i rc u i t f a u l t . The s ec on d f u n c t i o n o f i s o l a t i n g t r a n s f o r m e r s i s t o
p ro v id e e l e c t r i c a l i s o l a t i o n o f t h e lamp fr om t h e h ig h v o l ta g e c i r c u i t f o r s a f e t y
p u r p o s e s . C i r c u i t c o n t i n u i t y c a n a l s o b e a t t a i n e d by u s i n g b y- pa ss d e v i c e s , s u c h a s
f i l m c u t o u t s , w hi ch s h o r t a c r o s s t h e lamp when t h e l amp f a i l s , b u t i n t h i s a r r an g em e nt
t h e lamp may b e a t a h i g h p o t e n t i a l when t h e c i r c u i t i s e n e r g i z e d . I s o l a t i n g t r a n s-
f o rm e rs a r e us ed t o p ro v i de t h e p r o p er c u r r e n t t o t h e lamp i f t h e l amp c u r r e n t d i f f e r s
f ro m t h a t o f t h e s e r i e s c i r c u i t .
a > An i s o l a t i n g t r a n s f o r m e r c o n s i s t s of a pr imary and
a s e c on d a ry c o i l wound o n a m a g n e t ic c o r e i n a w a t e r p r o o f c a s e w i t h
p ri ma ry a nd s ec o nd a ry l e a d s f o r c o nn e c ti n g t h e s e r i e s c i r c u i t t o t h e
lam p. The p r im a ry a nd s e co n da ry c o i l s a r e i s o l a t e d e l e c t r i c a l l y b u t
l i n k e d by t h e m a g n et i c c i r c u i t . The s e c on d a ry c i r c u i t i s s u b je c te d t o a
l e s s e r e l e c t r i c a l p o t e n t i a l a nd on e s i d e of t h e s e c on d ar y s ho u l d be
b r o u gh t o u t t o a g r o u n d in g c o n n e c t io n . The c o r e of a n i s o l a t i n g t r a n s -
f o r m r i s m a g n e t i c al l y u n s a t u r a t e d i n o p e r a t i o n b u t becom es s a t u r a t e d i f
t h e lamp f a i l s o r t h e s e co nd ar y c i r c u i t i s o p e n - c i r c u i t e d , t h u s m ain -t a i n i n g t h e i n t e g r i t y o f t h e p rim ar y c i r c u i t . I f t h e lamp c i r c u i t
s h o ul d be s h o r t - c i r c u i t e d , t h e i s o l a t i n g t r a n s f o r m e r would b e i n a no-
l o a d c o n d i t i o n an d h a ve minimum e f f e c t o n t h e s e r i e s c i r c u i t . T he se
t r a n s f o r m er s s h o u l d b e c a pa b l e o f c o n t i nu o u s o p e r a t i o n a t r a t e d l o a d ,
o p e n - c i r c u i t , o r s h o r t - c i r c u i t w i t h o u t damage. The t u r n s r a t i o o f t h e
p ri ma ry c o i l t o t h e s e co nd ar y c o i l of a s e r i e s l s e r i e s t r a n s f o r m e r i s 1 :1
i f t h e lamp c u r r e n t i s t h e same a s t h e s e r i e s c i r c u i t c u r r e n t b u t i s
i n v e r s e l y p r op o r t i o na l t o t h e c u r r e n t r a t i o o t he r wi se .
b ) E n c l os u r e. The w a t er p r oo f c a s e f o r e n c l o s i n g t h e c o r e , w i n d i n g s , a n d
l e a d s may be of m e t a l , r u b be r , o r p l a s t i c a nd s h o u l d b e s u i t a b l e f o r
i n s t a l l i n g by d i r e c t b u r i a l , u nd er wa te r, i n b as e s , o r ex po su re d t o t h e
w e a th e r . T he c a s e s h o u ld p r o t e c t t h e u n i t f r o m damage i f t h e t r an s f o rm -e r i s dropped o r i s c a r r i e d by a s i n g l e l e a d . The c a s e s h o u l d p re v e n t
w a t e r f ro m e n t e r i n g t h r ou g h t h e c a s e o r w he re j o i n e d t o t h e l e a d s ,
m a i n t a i n r e s i l i e n c e t o a v o id s h a t t e r i n g o r d amage a t v e r y l o w te mp er a-
t u r e s , and p r o t e c t t h e u n i t d u ri n g h a n dl i n g, s t o r a g e , i n s t a l l i n g , a nd
s e r v i c e . The p r i m ar y l e a d s s h o u l d b e n o t l e s s t h a n 8.4 mm2 i n s i z e a nd
s h o u l d be i n s u l a t e d f o r n o t l e s s t ha n 5 000 v o l t s . T he se l e a d s s ho u ld
b e n o t l e s s t h a n 5 0 cm l o n g . U s u a ll y t h e s e l e a d s w i l l b e p r o vi d e d w i t h
a p l u g t y p e c on n e ct o r on o ne l e a d an d a r e c e p t a c l e on t h e o t h e r s u i t a b l e
f o r c o nn ec t in g t o t h e s e r i e s - c i r c u i t c a b l e . The s e c o n d a r ~ e a d s sh o ul d
b e tw o- co nd uc to r w i t h c o n d u ct o r s i z e n o t l e s s t h a n 3.3 mm a n d i n s u l a t e d
f o r n o t l e s s t h a n 6 00 v o l t s and h av e a l e n g t h o f n o t less t h a n 100 cm.
U s u a l l y t h e s e l e a d s a r e p r o v id e d w i t h a s u i t a b l e tw o- co nd uc to r c o n n e c t o r
f o r c o nn ec ti ng t o t h e l i g h t .
c ) Ambient t empe ra tu re . These t r ans fo rm ers shou ld be cap ab l e o f op e r a t in g
i n temp era tur es be tween -55°C and +65 "C .
d ) S e r i e s l s e r i e s i s o l a t i n g t ra n sf o rm e r r a t i n g s . R at in gs o f i s o l a t i n g
t r a n s f o r m e r s a r e by o u t p u t p ow er , p r i m ar y an d s ec o n d a r y c u r r e n t , t h e
f requency , and t h e i n s u l a t i o n v o l t a g e of p r im a ry an d s e c o n d a r y c i r c u i t s .
T h es e t r a n s f o r m e r s may b e e a s i l y m a n uf a ct u re d f o r a l m o s t a n y d e s i r e d
r a t i n g . Seme ccmr",cnly a v a i l a b l e r a t i n g s a r e a s f o l l o w s :
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1) Power. Rat ing s of 3 0 / 4 5 , 6 5 , 1 0 0 , 2 0 0 , 3 0 0 and 5 0 0 w a t t s a r e
f r eq ue n t ly used and somet imes 1 0 0 0 an d 1 5 0 0 w a t t u n i t s a r e us ed .
2) C u rr e nt . C u rr en t r a t i n g s a r e u s u a l l y g iv e n a s a r a t i o of p r i ma ry t o
seconda ry cu r r en t . Common cur ren t r a t in g s a r e 6 . 6 / 6 . 6 , 2 0 1 2 0 , 6.6,'-2 0 and 2 0 / 6 . 6 amperes.
3 ) Frequency. The common fr eq ue nc ie s a r e 5 0 and 6 0 h e r t z . P r e f e r a b ly
th e t rans fo rm er shou ld be used on the f requ ency fo r which i t was
des igned .
4 ) I n s u l a t i o n . Most i s o l a t i n g t r a ns f o rm e r s a r e i n s u l a t e d f o r 5 0 0 0
v o l t s on t h e pi i ma r y c i r c u i t and 6 0 0 v o l t s on t h e s e c on d a r y. L a r g e r
power s i ze s o f t r a ns fo r mers may re qu i r e a h i gh e r s econda ry ins u l a -
t i o n b e ca u se of t h e i r h ig h e r op e n -c i r cu i t v o l t a g e .
e ) S e v e r a l l am ps f ro m a s i n g l e t r a n s f o rm e r . P r e f e r a b l y e ac h l i g h t i s
s u p p l i e d b y i t s own i s o l a t i n g t rans fo rmer . Somet imes to reduce thei n s t a l l a t i o n c o s ts , su ch a s f o r i n s t a l l i n g c e n t r e l i n e l i g h t s on e xi s t -
in g n inways , o r t o reduce the mass and s t r en g t h of ca b l e s , as f o r t a l l
f r a n g i b l e a pp r o a ch l i g h t s u p p o r t s , s e v e r a l la mp s may be c o n ne c te d i n a
s e r i e s a c r o s s a s i n g l e i s o l a t i n g t r a n s f o r m e r. Of c o u r s e t h e tr a n s f o r m e r
must h av e t h e c a p a c i t y t o s u p p ly t h e t o t a l lamp l o a d p l u s l i n e l o s s e s .
Two p ro bl em s of t h i s a r ra n ge m en t a r e : f i r s t , i f one lam p f a i l s c a u s i n g
a n o p e n - c i r c u i t , t h e o t h e r l am ps a r e i n o p e r a t i v e u n l e s s s u i t a b l e b y- pa ss
d e v i c e s a r e u se d ; a n d s e c o n d l y , a t t h e i n s t a n t of t h e o p e n - c i r c ui t
f a i l u r e t h e i n s t a n t a n e o u s s e c o n da r y v o l t a g e may become v e r y g r e a t
e s p e c i a l l y f o r th e l a r g e r s i z e s of i s o l a t i n g t r a ns f o rm e r s. T he se
prob lems a r e d i s cu s se d below.
f ) E f f e c t s o f o p e n - c i r c ui t e d s e c o n d a r i e s o f i s o l a t i n g t r a n s f o r m e r s . Thed e s i g n of m ost i s o l a t i n g t r an s f o r m e r s l i m i t s t h e r o o t m e a n - s q u a r e ( r ms )
v o l t a g e of o p e n - c i r c u i t e d s e c o n d a r i e r s t o 3 0 0 v o l t s o r l e s s . H owever,
t h e i n s t a n t a n e o u s v o l t a g e of some i s o l a t i n g t r a n s f o r m e r s a t t h e t i me t h e
ope n-c i rc ui t occ ur s may exceed 1 0 0 0 v o l t s . I s o l a t i n g t r an s f or m e r s w i t h
m ag ne ti c c o re s d e si g ne d t o s a t u r a t e a t a v o l t a g e o n l y s l i g h t l y g r e a t e r
t h a n t h e i r o p e r a t i n g v o l t a g e u s u a l l y ha ve l o w e r r m s a n d i n s t a n t a n e o u s
p e ak o p e n - c i r c u i t s e c on d a ry v o l t a g e s t h a n do l e s s s a t u r a t e d t r a n s f o r m -
e r s . H i g h r m s o p e n - c i r cu i t v o l t a g e s r e q u i r e h i g h e r se c on d ar y i n s u l a t i o n
a nd p r e s e n t a g r e a t e r e l e c t r i c a l s ho ck h a z a r d , b u t t h e y a l s o make f i l m
c u t o u t o p e r a t i o n s more r e l i a b l e . The r e a c t a n c e of s e r i e s / s e r i e s i s o l a t -
i n g t r a n s f o r m er s w it h o p en - c i r c u i t s e c o n d a r ie s d i s t o r t s t h e p r i m ar y
c u r r e n t wa ve fo rm , a n d t h e r e s u l t i n g h a rm o n ic f r e q u e n c i e s may a f f e c t t h e
re gu la t i on of some types of cons tan t -cu r ren t re gu la to rs .
g ) Lamp by-pass dev ic es . Whe ther l amps a r e connec ted d i r e c t ly in t o th e
s e r i e s c i r c u i t o r a s a gro up i n s e r i e s a c r o ss a s i n g l e i s o l a t i n g t ra n s -
fo rmer , when the f i l am en t o f one lamp burns ou t , a l l the l amps of th e
g r ou p a r e o u t u n l e s s a s u i t a b l e by -p ass d e v i c e i s c o n n e c t e d a c r o s s t h e
t e r m i n a l s of t h e f a i l e d la mp . From t h e e a r l y da ys of s e r i e s l i g h t i n g
c i r c i n i ts wi tb -- ,* i s o l a t t n g t r a n s f ~ r m e r s , u s e d f i l m c u t o u ts have been
u s ed t o b y- pa ss f a i l e d l am ps . F or t h i s d e v i c e , sp r i n g- l o ad e d c o n t a c t s
a re c o n ne c t ed a c r o s s t h e t e r m i n a l s of each lamp. The s p r i n g - l o a d e d
consarrs zrcl separa ted by 3 f i l n l c i l t o u ~w h i c h i s a s m a P i eisk of a tklm
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n o n- c on d uc t in g f i l m b et we en c o n d u c t in g o u t e r s u r f a c e s . When t h e lamp i s
o p e r a t in g , t h e f i l m d i s k ke ep s t h e lamp t e r d n a l s i n s u l a t e d f ro m e ac h
o t h e r a nd t h e lam p f i l a m e n t c o mp l et es t h e s e r i e s c i r c u i t . I f a lam p
f i l am e n t f a i l s , t h e v o l ta g e ac r o s s t h e lamp t e r m in a ls r a p i d l y r i s e s t o a
v a l u e (pe rhaps 1 000 v o l t s ) wh ic h p e r f o r a t e s t h e f i l m a nd s h o r t s o u t t h e
lamp t e r m i n a l s an d r e s t o r e s t h e s e r i e s c i r c u i t b e f o r e t h e c o n s t a n t -
c u r r e n t r e g u l a t o r ' s o p e n - ci r cu i t p r o t e c t i o n o p e r a t e s. When t h e lamp i s
r e p l a c e d a new f u s e d f i l m c u t o u t m ust be i n s t a l l e d . The o u t a g e o f t h e
o t h e r l am ps o f a s m a ll c i r c u i t c o n ne ct ed i n s e r i e s w i t h t h e s ec o nd a ry of
a n i s o l a t i n g t r a n s f o r m e r when o ne lamp f a i l s may n o t b e a c c e p t a b l e , an d
b y - p a s s d e v i c e s f o r t h e s e la mp s a r e n ee de d. The o p e n - c i r c u i t s e c o n d a r y
v o l t a g e p e a k o f some i s o l a t i n g t r a n s f o r m e r s may be 1 0 0 t o 2 0 0 v o l t s o r
l e s s . Fused f i l m c u t o u t s w hi ch o p e r a t e a t t h e s e v o l t a g e s a r e a v a i l a b l e
b u t may be u n r e l i a b l e a s t h e o p e n - c i r cu i t v o l t a g e may f a i l t o p e r f o r a t e
t h e f i l m c u t o u t an d s h o r t o u t t h e f a i l e d lamp. A recen t deve lopment o f
a b y-pass d e v i c e f o r l am ps i n t h e s e c i r c u i t s i s a s h o r t i n g r e l a y . T he se
r e l a y s a r e more e x p e n si v e t h a n f u s e d f i l m c u t o u t s b u t p r o v i d e m ore
r e l i a b l e o p er a t io n .
3.2.1.8 C on ne ct io ns f o r s e r i e s c i r c u i t s . The c o n ne c t io n s i n s e r i e s c i r c u i t s s h o u l d
b e c a r e f u l l y made t o a s s u r e c i r c u i t c o n t i n u i t y a nd t o p r e v e n t d ev el op m en t o f g ro un d
f a u l t s . An o p e n -c i r cu i t f a u l t i n t h e p ri ma ry w i l l c au se an ou ta ge of a l l l i g h t s i n
t h a t c i r c u i t . U nl es s t h e c o n st a n t- c u rr e n t r e g u l a t o r i s e q ui p pe d w i t h o p e n - c i r c u i t
p r o t e c t i o n , t h e r e g u l a t o r may b e dam aged. Most g r ou n d- t yp e f a u l t s o n s e r i e s c i r c u i t s
o c c u r a t c o n ne c t io n s . A s i n g l e gr ou nd f a u l t d o es no t c a u s e a n ou t a ge of t h e l i g h t s , b ut
two o r more g round f a u l t s w i l l s h o r t - c i r c u i t a l l l i g h t s between t h e f a u l t s .
3.3 PARALLEL (MULTIPLE) CIRCUITRY
3.3.1.1 The u se of p a r a l l e l ( m u l t i p le ) c i r c u i t s f o r a v i a t i o n g ro un d l i g h t i n g i s n o t
recommended f o r l a rg e ae rodromes and /o r compl ica ted l i g h t i n g sys tems f o r t h e f o ll o wi n g
r e a s o n s :
a ) p a r a l l e l c i r c u i t s u s u a l l y e n t a i l a much more ex p en s iv e c a b l i n g i n s t a l l -
a t i o n t h an do es a h ig h- vo lt ag e s e r i e s c i r c u i t ;
b ) a c cu r a te b r i l l i a n c y b a la nc e of a l l l i g h t s i n t h e p a t t e r n c an no t b e
o b t a i n e d e a s i l y ; and
c ) t h e mass b ur n o u t of l am ps i n a c i r c u i t i s much more l i k e l y d u e t o t h ei n a b i l i t y o f a v e ra ge v o l ta g e r e g u l a t o r s t o c o n t r o l v e ry r a p i d f l u c t u a-
t i o n s i n i nc om in g su p p ly v o l t s .
3.3.1.2 I n v ie w o f t h e s e c o n s i d e r a t i o n s , p a r a l l e l c i r c u i t s s h o u l d o n l y b e u se d when
t h e r e a r e o n ly a few f i t t i n g s e x i s t i n g i n t h e c i r c u i t and a c cu r a te i n t e n s i t y b al an ce i s
n o t c r i t i c a l ; f o r ex am pl e, a s h o r t t ax i wa y . S m al l er a er od ro m es w i t h s h o r t runw ays a n d
t a x iw a y s c an employ p a r a l l e l v o l t a g e f o r t h e l i g h t i n g .
2 2 1 2J O J - I e J E f f e c t s ~f f a u l t s . I f t h e l i g h t f i x t u r e s a r e connec ted a c r o s s t h e l i g h t i n gcircui t , L UL , l c ~ - O i i taiiiipr a n op t . n - c i r e u i ta u l t in a fixture oes : lo t s e r io i ; s l y
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a f f e c t t h e l i g h t i n g c i r c u i t , b u t a s h o r t -c i r c u i t f a u l t w i l l b e a n o ve r lo a d c o n d i t i o na n d , d e p en d i ng o n w h ic h p r o t e c t i v e d e v i c e ( f u s e o r c i r c u i t b r e a k e r ) o p e r a t e s , may make
t h e c i r c u i t o f l i g h t s i n op e r a ti v e . To p r o t e c t t h e l i g h t i n g c i r c u i t , o f t e n e a ch lamp i s
c o nn e ct ed t o t h e l i n e v o l t a g e s i d e of t h e c i r c u i t by a f u s e .
3. 3.1 .4 Most p a r a l l e l - t y p e l i g h t f i x t u r e s a r e d e s i g n ed f o r
lo w a p p l i e d v o lt a g e s ( l e s s t h a n 3 00 v o l t s ) , and t h e c i r c u i t v o l t a g e i s t h a t r e q u i r e d by
th e l amps o r st ep -down t rans fo rm ers a r e u sed . The l i g h t s may be sup p l i ed f rom a s in g l e
c i r c u i t c o nn e ct ed b et we en t h e l i n e and n e u t r a l o r by a l t e r n a t i n g be tw ee n n e u t r a l an d
l i n e v o l t a g e on e ac h s i d e of t h e n e u t r a l . Examples o f t h e s e c i r c u i t s a r e 12 0 v o l t s
l i n e - t o - n e u t r a l a nd 2401120 v o l t ( 24 0 v o l t s l i n e - t o - l i n e and 1 20 v o l t s l i n e - t o - - n e u t r a l )
c i r c u i t s . O th er v o l t a g e s a r e o f t e n u s ed . U su al ly t h e c a b l e i n s u l a t i o n of p a r a l l e l
l i g h t i n g c i r c u i t s i s r a t e d a t 600 v o i t s , which limits t h e vo l ta g e f o r p a r a l l e l l i g h t i n g
c i r c u i t s t o n o t m ore t h a n 500 v o l t s .
3.3.1.5 S tep-down t r a n s f o r m e r s . The u s e of h i g h e r v o l t a g e s f o r t r a n s m i s s i o n o f
p ow er r e d u ce s t h e l i n e v o l t a g e d r o p a n d t h e n st ep -do wn d i s t r i b u t i o n t r a n s f o r m e r s r e d u c e
t h e v o l t a g e t o t h a t more s u i t a b l e f o r l o c a l d i s t r i b u t i o n . S i m i l a r l y , t h e power t o a e ro -
drome l i g h t i n g c i r c u i t s may be a t a h i g h e r v o l t a g e o n t h e f e e d e r c i r c u i t s a n d r ed u ce d by
a step-dow n t r a n s f or m e r a t t h e b eg i n ni n g o f t h e l i g h t i n g c i r c u i t t o ma tc h t h e d e s i r e d
c i r c u i t v o l t a ge . Of c o u rs e , t h e s e f e e d e r c a b l es must be a d eq u a te l y i n s u l a t e d f o r t h e
fe ede r vo l t ag e . Somet imes i t i s d e s i r a b l e t o u s e l o n g l o w -v o l ta g e c ab l e s f o r f e e d e r s ,
s u c h a s when t h e s e c a b l e s a r e a l r e a d y i n s t a l l e d a nd a v a i l a b l e . A ssuming t h e s e f e e d e r s
h a ve 6 0 0 - v o l t i n s u l a t i o n , t h e l i n e d ro p ca n b e r ed u ce d by u s i n g a h i g h e r v o l t a g e w i t h i n
t h e i n s u l a t i o n l i m i t o f t h e c a b l e on t h e f e e d e r s a nd r e d u c i n g t h e v o l t a g e w i t h s tep -d ow n
t ra ns f or m er s a t t h e i n p ut t o t h e c i r c u i t o r t o t h e i n d iv i d u a l l i g h t f i x t u r e s . An
example i s t o u s e 4 80 v o l t s o n t h e f e e d e r s a nd step-down t o 1 20 v o l t s a t t h e l i g h t i n g
c i r c u i t . Use o f la mp s i n t h e v o l t a g e r a n ge o f 6 t o 3 0 v o l t s i n aer od ro me l i g h t f i x t u r e s
i s us ua l ly more e f f ec t i v e than th e u se of 120 o r o f 240 v o l t l amps. Thus , when s t ep -
down t r an s f o r m e rs a r e t o b e us ed f o r i n d i v i d u a l l i g h t s , o r f o r a s m a l l g ro u p of l i g h t s
i n a b a r r e t t e , c o n s i d e r a t i o n s h o u l d b e g i ve n t o c h oo s in g l i g h t s wh ic h u s e l ow -v ol ta ge
l am ps . U n le s s i n d i v i d u a l l y f u s e d , s tep -d ow n t r a n s f o r i n e r s u s e d a s i n d i c a t e d abave s h o u l db e of t h e h i gh - re ac ta nc e t y p e s o t h a t a s h o r t - c i r c u i t i n t h a t p a r t o f t h e l i g h t i n g
sys tem fe d by one t r ans f o rme r w i l l n o t c a us e f a i l u r e of t h e e n t i r e s y st em .
3 .3 .1 .6 The u s e o f a c o n s t a n t v o l t a g e t r a n s f o r m e r a t
t h e l o c a t i o n o f a l i g h t s u p p l i e d by a l o n g f e e d e r c a b l e t o c o mp en sa te f o r l i n e - v o l t a g e
drop changes may be advantageous. For example , an aerodrome beacon su pp l i ed by a l o n g
f e e d e r c a b l e w hi ch a l s o s u p p l i e s a number of i n t e r m i t t e n t l o a d s w hi ch c a u s e s t h e l i n e -
v o l t a g e d r op t o f l u c t u a t e w i de ly .
3.4 CONTROL OF AERODROME LIGHTING SYSTEMS
3.4.1 , l The c o n t r o l c i r c u i t r y f o r ae ro dr om e l i g h t i n g p r o v i d e s t h e m eans o f s w i t c h i n g
o n o r o f f an d o f c ha ng i ng t h e i n t e n s i t y of t h e v a r i o u s l i g h t i n g s y s te m s . T h es e c o n t r o l s
may be manual o r auto mat ic .
3.4.1.2 Local manual co nt ro l . Tne s i m p l e s t c o n t r o l s ys t em i s a s w i t c h a t t h e power
s u p p l y u n i t of t h e c i r c u i t . which i s o p e r a t e d by a p er s on t o e n e r g i z e o r d e e n e s g i z e the
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c i r c u i t . T h is c o n t r o l method i s used a t some s m a l l aerodromes o r some misce l la neo us
a s s o c i a t e d l i g h t i g c i r c u i t s . Some a er od ro me s may u s e l o c a l m an ua l c o n t r o l s as an
a l t e r n a t e c o n t r o l p o i n t f o r e mergency o p e r a t i o n s .
3.4.1.3 Remote control . The l i g h t i n g s y s te m s f o r l a r g e r a e r od r om e s a r e c om pl ex a nd
p r o p e r c o n t r o l i s r e l a t e d t o a t m os p h er i c c o n d i t i o n s , t i me o f d ay , p e r h ap s t h e p i l o t ' s
p r e f e r e n c e , th e po s i t io ns and manoeuvr ing of s e v e r a l a i r c r a f t , and o t h e r a c t i v i t i e s on
t h e f i e l d . The pe r s on o r p e r so n s m ost k no wl ed ge ab le of t h e s e c o n d i t i o n s a r e t h e a i r
t r a f f i c c o n t r o l l e r s ; t h e r e f o r e , m ost of t h e ae ro dr om e l i g h t i n g c o n t r o l s a r e on a r em ot e
l i g h t i n g c o n t r o l p a ne l i n t h e a er od ro me c o n t r o l t ow er an d op e r at e d by t h e t r a f f i c
c o n t r o l l e r s . Some a er od ro me s may h a ve s p e c i a l c o n t r o l s t a t i o n s o t h e r t h a n i n t h e
c o n t r o l t ow er w i th t h e o p e r a t o r i n d i r e c t c om munication w i t h t h e a i r t r a f f i c c o n t r o l l -
e r s . The r em o te l i g h t i n g c o n t r o l p a n e l i s c on ne ct ed t o t h e a p p r o p r ia t e l i g h t i n g v a u l t
by a s ys te m o f c o n t r o l c a b l e s t o p r ov i d e c a p a b i l i t y o f c o n t r o l l i n g t h e v a r i o u s l i g h t i n g
c i r c u i t s .
3.4.1.4 T yp es of r em ot e c o n t r o l sy s t em s . S e v e r a l t y p e s of c o n t r o l s y s t e m s a r e u s e d
f o r a er od ro me l i g h t i n g . A l t e r n a t i n g c u r r e n t ( a c ) power i s o f t e n u se d t o e n e r g i z e t h e
c o n t r o l s . T h is a c power may be a t t h e l o w d i s t r i b u t i o n v o l t a g e o r a t a s p e c i a l v o l ta g emore s u i t a b l e f o r t h e l e n g t h of t h e c o n t r o l c a b l e r u n s and t h e s i z e o f t h e c o nd u ct o r.
T he se c o n t r o l s may b e c on n e ct e d d i r e t l y t o t h e power c o n t r o l d e v i c e f r o m t h e r e m ot e
c o n t r o l p a n e l o r by a u x i l i a r y r e l a y s t o o p e r a t e t h e c o n t r o l d e v ic e s. Some c o n t r o l
c i r c u i t s u s e d i r e c t c u r r e n t f o r t h e c o n t r o l v o lt a g e, e s p e c i a l l y t o re du ce i n d u c t i v e
c o u p l i n g be tw ee n c i r c u i t s . Some m a jo r a er o dr o me s w i t h v e r y c om pl ex c o n t r o l c i r c u i t s u s e
m u l ti p l ex c o n t r o l s y st em s t o p r ov id e g r e a t e r f l e x i b i l i t y f o r e x t e n si o n s an d v a r i a t i o n s
t o l i g h t i n g p a t t e r n s a nd t o f a c i l i t a t e ch an ge s i n t h e c o n t r o l r eq u ir em e nt s. Some a er o-
dromes u se r a d i o s i g n a l s f o r c o n t r o l , e i t h e r a i r- t o -g r o un d f o r p i l o t s o r gr ou nd -t o
g ro und f o r e qu ip men t l o c a t e d i n a r e a s n o t e a s i l y a c c e s s i b l e t o c o n t r o l c i r c u i t s . These
c o n t r o l sy s te m s s h o u l d b e c a p a b l e o f a h i g h d e g r e e o f o p e r a t i o n a l r e l i a b i l i t y an d s h o u l d
be d es ig ne d t o pr o vi de , a s f a r a s po s s i b le , t h e i n t e g r i t y o f t h e l i g h t i n g p a t t e r n s
s e l e c t e d r e g a r d l e s s of c o n t r o l c a b l e f a u l t s o r eq ui pm ent f a i l u r e s . S o l id s t a t e e qu i p-
ment may be u se d w he re p r a c t i c a b l e , a l t h o u g h r e l a y s may be more s a t i s f a c t o r y a t t h ei n t e r f a c e b etw een t h e c o n t r o l c i r c u i t s a nd t h e l i g h t i n g c i r c u i t power e q ui pm e nt .
C o n t r o l p a n e l s
3.4.2.1 Pr imary co n t ro l pane l . The p r imary co n t ro l pan e l i s u s ua l ly l o c a te d i n t h e
c o n t r o l t ow er a t a l i g h t i n g c o n t r o l de sk o r pa n el . T h i s p a n el s ho u ld be d e s ig n e d t o
p r ov id e t h e o p e r a t o r wi th c o n t r o l s w i t c he s , o p e r a t i n g c i r c u i t i n d i c a t o r l i g h t s and
i n t e n s i t y c o n t r o l s , and t h e i r a s s o ci a t e d i n d i c a t i n g f e a t u r e s whi ch a r e e a s i l y i n d e n t i f i -
a b l e un de r a l l c o n d i t io n s o f i l l u m i n a t i o n i n t h e c o n t r o l room. F or t h i s p u r p os e i t may
b e ne c e ss a r y t o p r o v i de s e l f - i l l u m i n a t e d l eg e nd s f o r c o n t r o l s e l e c t o r s and a desk
b r i l l i a n c y l e v e l s e l e c t o r f o r t h e i n d i c a t o r lamps. T he re a r e a d v a n ta g e s t o b e d e r i v e d
f ro m a s t a n d a r d i ze d f or m o f l a y o u t f o r c o n t r o l and i n d i c a t i n g f a c i l i t i e s a n d t h e c u r r e n t
t r e n di s
t o wa r ds s t a n d a r d m o du la r p a n e l l a y o u t s . E ac h s e r v i c e s h o u l d b e p r o v i d e d w i t hi t s own c o n t r o l s e l e c t o r an d g r o u p o f i n d i c a t o r l am ps . Where a s e p a r a t e c o n t r o l d es k i s
prov ided f o r each runway , a d iag ram can be combined wi th t h e co n t ro l desk b u t where one
c o n t r o l d e s k s e r v e s t h e w h ol e a i r p o r t a s e p a r a t e f a c s i m i l e d i a gr am may n ee d t o b e
prov ided . Complex t a x i i n g g u id a nc e s y st em s u s i n g s e l e c t i v e s w i t ch i n g o f c e n t r e l i n e
l i g h t s and s t o p b a r s c an b e s t b e c o n t r o l l e d f ro m a n o p e r a t i o n a l d ia gr am f i t t e d w it h
co mb in ed i n d i c a t i o n l a m pl p us h b u t t o n s f o r s t o p b a r s a nd i n d i c a t o r l a mp s f o r t a x iw a y
r o u t e s .
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3.4.2.2 F a c s i m i l e d i a gr a m s a r e r e q u i r e d f o r a e r od r o m es h a v in g
co mp le x p a t t e r n s . They a r e s p e c i a l l y made t o s u i t i n d i v i d u a l l a y o u t s an d s o i n v o l v e
c o n s i d e r a b l e c o s t . P a ne ls w i t h runw ays an d t ax i wa y s d e l i n e a t e d i n a c o n t r a s t i n g c o l o u r
a r e accommodated t o p r o v id e a d ia g ra m ma ti c d i s p l a y of l i g h t i n g s e r v i c e s . F i b r e o p t i c s
may a l s o b e u se d f o r t h i s p u r po s e.
3 .4 .2 .3 C o n t r o l s . The s w i t c h e s a nd c o n t r o l s s h o u l d b e t y p e s w hi ch a r e e a s y t o
i d e n t i f y , p r o vi d e p o s i t i v e i n d i c a t i o n of t h e o p e r a t i n g s t a t u s , and be gr ou pe d t o
a s s o c i a t e r e l a t e d f u n c t i o n s an d c i r c u i t s . T hese c o n t r o l s s h o ul d be a t y p e w hi ch a r e n o t
e a s i l y s w i tc h ed i n a d v e r t e n t l y .
3.4.2.4 A l t e r n a t e c o n t r o l p a n e l . P r o v i s i o n s h o u l d be made f o r l o c a l c o n t r o l o f
aerodrom e l i g h t i n g i n t h e l i g h t i n g v a u l t s o r c o n t r o l c e n t r e s t o e n a bl e o p e r a t i o n of t h e
l i g h t i n g s y s t e m s a t t i m es when t h e r em ot e c o n t r o l s y s t e m i s i n o p e r at i v e . A l l l i g h t i n g
s y st e ms e s s e n t i a l t o t h e a er od ro me o p e r a t i o n s h o ul d ha ve a n a l t e r n a t e c o n t r o l p a n el .
The a l t e r n a t e c o n t r o l p a ne l s h o u ld be l o c a t e d s o t h a t i t i s a c c e ss i b l e t o a n o p er a to r
w i t h o u t h i s h a v i n g t o e n t e r a n a r e a h o u s i n g h i g h v o l t a g e e qu ip me nt o r s w i t c h g e ar .
O ft en t h e a l t e r n a t e c o n t r o l pa n e l i s l o ca t ed i n a s e c t i o n of t h e l i g h t i n g v a u l t n e a r t h e
e n t r a n c e , w h i c h i s s e p a r a t e d f r o m t h e a r e a c o n t a i n i n g t h e pow er e q u ip m en t . U s u a l l y o n l yo ne a l t e r n a t e c o n t r o l p a ne l i s prov ided , and i t i s l o c a t ed i n t h e v a u l t c o n t a i n in g t h e
e qu ip m en t f o r s u p pl y i ng power t o t h e p a r t i c u l a r l i g h t i n g c i r c u i t s i n v o l ve d . T hu s t h e r e
may be s e v e r a l a l t e r n a t e c o n t r o l pa n e l s , e ac h of w hi ch c o n t r o l s d i f f e r e n t c i r c u i t s .
Some a er o dr o me s may u s e a c e n t r a l a l t e r n a t e c o n t r o l p a n e l , s i m i l a r t o t h e p r i m a r y r em o te
c o n t r o l p a n e l l o c a t e d i n a c o n t r o l c e n t r e , f o r em er ge ncy o p e r a t i o n s . C o n s ta n t -c u r re n t
r e g u l a t o r s u s u a l l y p r ov i d e c o n t r o l s on e a ch r e g u l a t o r f o r o p e r a t i o n o f t h a t r e g u l a t o r
f o r m ai n t en a n ce o r d u r i n g a n e me rg en cy . A u t ho r i ze d p e r s o n s a r e u s u a l l y t h e o n l y o n es
p e r mi t te d t o o p e r a te t h e s e c o n t r o l s .
3.4.2.5 T r a n s f e r r e l a y pa n e l. F or s a f e t y o f m ai n te n an c e p e r s o n n e l a n d t o a v o i d
c o n f l i c t i n g o p e r a t io n of t h e c o n t r o l s , o n ly on e c o n t r o l s t a t i o n s ho u l d b e a b l e t o op er -
a t e a g iv en c i r c u i t a t a ny ti me . T r an s fe r r e l a y p an el s a r e u se d t o s w it c h t h e o p e r a t in g
c a p a b i l i t y f ro m t h e p r i m ar y c o n tr o l. pan el. t o t h e a l t e r n a t e c o n t r o l p a n e l , To accommo-d a t e a l l t h e c o n t r o l c i r c u i t s i nv ol ve d i n t h e t r a n s f e r , s e v e r a l t r a n s f e r c o n t r o l p an e l s
may be u se d b u t u s u a l ly a s i n g l e t r a n s f e r s w i t c h a c t u a t e s a l l of t h e c o n t r o l p a n el s .
The t r a n s f e r c o n t r o l p a n el s and t h e t r a n s f e r s w i t ch a r e u s u a l l y l o c a t e d a t t h e s i t e o f
t h e a l t e r n a t e c o n t r o l p an el .
3.4.3 Use of r el a y s
3.4.3.1 R el ay p a n el s f o r l o n g c o n t r o l c i r c u i t s . Where c o n t r o l c i r c u i t s a r e l o n g ,
t h e v o l t a g e d r o p i n t h e l i n e s may be s u c h t h a t p ower c o n t r o l d e v i c e s c a n no t b e o p e r a t e d
d i r e c t l y f ro m t h e pr i ma ry r em o te c o n t r o l p a n e l . Even c i r c u i t s w hi ch e a r l i e r o p e r a t e d
s a t i s f a c t o r i l y may become i n o p e r a t i v e a f t e r a d d i t i o n a l c o n t r o l c i r c u i t s a r e a dd ed . To
p e r m it c o n t r o l a t t h e l o n g e r d i s t a n c e , r e l a y s w i t h l o w - cu r r e n t c o i l s may be u s e d t o
e n e r g i z e t h e c o n t r o l s of t h e pow er e qu ip me nt . T h es e r e l a y s a r e o f t e n a s s e mb l e d i np a n e l s c o n t a i n i n g s e v e r a l (1 6 o r mo re) r e l a y s . ( Th es e r e l a y p a n e l s a r e s om et im es c a l l e d
p i l o t r e l a y p an el s .) A r e l a y may be p r o vi d e d f o r e a c h c o n t r o l l i n e f r om t h e p r i m a r y
r em ot e c o n t r o l pa n e l. The c o n t a c t s o f t h e s e r e l a y s c o n t r o l t h e power t o t h e s w i t c h e s o r
co n t ro l s of th e power equ ipment func t ion s .
3 .4 .3 ,2 Some i n d i v i d u a l v i s u a l a i d s o r s h o r t l i g h t i n g c i r c u i t s
( ae ro dr om e b ea co ns , w ind d i r e c t i o n i n d i c a t o r s , s e c t i o n s of o b s t a c l e l i g h t s , s i m p l e
a p p ro a c h l i g h t i n g sy s t em s , e t c . ) may o b t a i n power f ro m a l i g h t i n g v a u l t o r f r o m a l o c a l
so ur ce of power . If t h e power is; froin a l o c a l scjurce, t h e r e l a y f o r c o n t r o l l i n g t h es eruwcr, If t h el i g h t s is u s u a l l y l o c a t ed a t o r t h e l i g h t o r s oi ir ce o f
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c a b l e s a r e l o n g , t h e c o n d u ct o rs o f t h e c o n t r o l c a b l e may n ee d t o b e l a r g e t o r e d uc e t h e
v o l t a g e d r o p . The r e l a y s h ou ld b e s e l e c t e d t o o p e r a t e f ro m t h e c o n t r o l v o l t a g e a v a i l -
a b l e when t h e r e l a y i s a c t u a t e d . Al so i f t he r e l a y i s t o b e l o c a t e d o u t d o o r s , i t w i l l
ne ed t o be p rov i ded w i t h p r o t e c t i o n f rom t h e most s e ve r e w e a t he r t o w hi c h i t w i l l be
s u b j e c t e d . It s h o ul d ha ve a p r o v i s i o n t o l o c k i t f o r s e c u r i t y .
3 .4 .4 I n t e r c onne c t i on o f c o n t r o l s
3.4.4.1 O ft en t h e o p e r a t i o n s a t t h e a ero dr om e a r e s u c h t h a t c e r t a i n c o m b in a t io n s o f
l i g h t s a r e a lw ay s u se d t o g e t h e r o r o t h e r c om b in a ti o ns a r e p r o h i b i t e d . E xa mp le s a r e :
a ) runway e dge l i g h t s , t h r e s h o l d l i g h t s , a nd runway end l i g h t s may be
ope ra te d a t t he same t ime a l though th e power may be provi ded f rom
d i f f e r e n t c i r c u i t s ;
b) runway e dge l i g h t s may be ope r a t e d w i t hou t t h e runway c e n t r e l i n e l i g h t
b u t i f t h e runway c e n t r e l i n e l i g h t s a r e u s e d t h e runway e d g e l i g h t s a r e
a lways energ ized ;
c ) t h e s e q ue n c ed - fl a sh i n g l i g h t s o f t h e a p p ro a c h l i g h t i n g s y s t e m c an b e
us e d on l y when t h e i nc a nde s ce n t l i g h t s of t h e s y s t e m a r e a t t h e h i g he r
i n t e n s i t y s t e p s ;
d ) s e t t i n g of t h e i n t e n s i t y c o n t r ol f o r a g i ve n a t m os ph e r i c c ond i t i o n may
o p e r a t e t h e a p pr oa ch l i g h t i n g s ys te m a t o ne i n t e n s i t y s t e p , t h e runway
l i g h t s a t an o t he r i n t e n s i t y s t e p , a nd t h e t ax iw ay l i g h t s a t y e t a n o t h e r
i n t e n s i t y s t e p ; and
e ) i n t e r s e c t i ng runw ays s hou l d no t be l i gh t e d s i m u l t a ne ous l y . O nl y by
p r o p e r ly i n t e r c o n ne c t i n g t h e c o n t r o l s and c o n t r o l c i r c u i t s , c an t h e
de s i r e d c om bi nat i ons be ob t a i ne d o r unde s i r e d c om bi na ti ons p r oh i b i t e d
w i t h s i m p l e r o p e r a t i o n s by t h e c o n t r o l l e r an d l e s s e r ch a n ce of e r r o r ;Each a er od rome s hou ld c ons i de r pos s i b l e c o n t r o l i n t e r c on ne c t i o n
c om bi na ti on s i n r e l a t i o n t o t h e i r i n s t a l l a t i o n s and o p e r a t i n g
procedures .
3.4.5 A ut om a t i c c on t r o l s
3.4.5.1 Some t ype s o f a er od rome l i gh t i ng a i d s may be c on t r o l l e d s a t i s f a c t o r i l y by
a u t om a t ic c o n tr o l s . More o f t e n t h e s e au t o ma t ic c o n t r o l s a r e us ed a t s m a l l e r a i r p o r t s ,
b u t t h e y may be us ed f o r l e s s c r i t i c a l v i s u a l a i d s a t l a r g e ae ro dr om es e s p e c i a l l y a t
l o c a t i o n s n o t e a s i l y c on ne ct ed t o t h e c o n t r o l c i r c u i t s . P h o t o e l e c t r i c c o n t r o l s may b e
us ed t o e ne r g i z e a nd de e ne r g i z e ae rodr om e be a cons , w ind d i r e c t i o n i n d i c a t o r s , a nd
o b s t a c le l i g h t s i n l e s s c r i t i c a l a r e a s . The c o n t r o ls a r e u s u a l ly a c t u at e d by sk y
i l l u m i n a n ce l e v e l s . Most of t h e s e c o n t r o l s e n e r g i z e t h e c i r c u i t when t h e i l l u m i n a n c ef rom the n o r t h s k y d e c r e a s e s t o a b o u t 400 l u x an d d e e ne r g i z e s t h e c i r c u i t when t h e
i l lum i- nanc e i nc r e a s e s t o a bou t 600 l ux . T im e- cl oc k c on t r o l s may be u s e d t o a u t om a t i c a l -
l y c o n t r o l t h e a e ro dr om e l i g h t i n g a t a e ro dro me s w i t h n on -i n st ru m en t c a p a b i l i t y o n l y .
Time-clock c o n t r o l s a r e o f t e n us ed a t a er od ro me s w here t h e v i s u a l a i d s a r e t u r n e d o f f
a f t e r a c e r t a i n h ou r a t n i g h t t o c on s e rv e e n e rg y . T he rm al c o n t r o l s may b e u s ed t o
a c t u a t e h e a t e r s of some v i s u a l a i d s t o p r ev e n t t h e f o r m a ti o n o r a c c u m u l a t io n of i c e ,
snow o r c onde nsa t i on . T he se t he r m a l c on t r o l s may be ob t a i n e d w i t h f i x e d o r a d j u s t a b l e
c o n t r o l f o r many d i f f e r e n t t e m p e r a tu r e s . Some i n s t a t l a t i o n may ne ed ma nu al c o n t r o l t o
o v e r r i d e t h e a u t o m at i c c u i i t r u i o f c e r t a i n lighting circulLts .
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3.4 .6 Radio remote co nt ro ls
3.4.6.1 R ad io s i g n a l s f ro m a i r c r a f t t o c o n t r o l a er od ro me l i g h t i n g s y s t e m s h av e b ee n
u se d, t o a l i m i t e d d e g re e , a t s m a l l e r ae ro dr om es f o r s e v e r a l y e a r s . T h i s c o n t r o l method
h a s s e v e r a l a d v a nt ag e s i n t h a t i t p er mi ts t h e p i l o t t o s e l e c t t h e l i g h t i n t e n s i t y of h i s
c h o i c e , e l i m i n a t e s t h e ne ed f o r c o s t l y c o n t r o l c a b l e s , an d co n s er v e s power by h a v in g t h e
l i gh t i n g sys t em deene rg ized when no t needed . R ad io c o n t r o l s f o r a i r - t o - g r o u n d , g ro un d-
to-ground, and a combina t ion of a i r - to-ground and ground-to-ground systems a r e
a v a i l a b l e . R adio c o n t r o l c an p r o vi d e i n t e n s i t y c o n t r o l a s w e l l a s e n e r g i z i n g t h e
l i g h t i n g c i r c u i t s . Most r a d i o c o n t r o l s au t o ma t ic a ll y d e en e rg i ze t h e l i g h t i n g c i r c u i t s
15 t o 6 0 m in ut es a f t e r t h e l a s t c o n t a c t . R adio c o n t r o l s h av e b een us ed t o c o n t r o l
runway e d ge l i g h t s , t a xi w ay e d ge l i g h t s , s i m p le ap p ro a ch l i g h t i n g s y s t e m s , v i s u a l
a pp ro ac h s l o p e i n d i c a t o r s y st em s , a s i n d v i d u a l s ys t em s o r i n p r e d e t e r d n e d c o mb i na ti o ns .
R ad io c o n t r o l o f a e ro dr om e l i g h t i n g s ys te ms f r o m a i r c r a f t s h o u ld b e us e d o n l y a t
u n c o n t r o l l e d a e r o d r o m e s o r a t o t h e r a er od ro me s du r i n g p e r i o d s when t r a f f i c c o n t r o l i s
n o t i n o p e r a t i on . L i g h t i n g s y st em s w hi ch s h o ul d n o t b e r a d i o c o n t r o l l e d i n c l u d e
o b s t a c l e l i g h t s , a er od ro me b ea c o ns , p r e c i s i o n a p p ro a ch l i g h t i n g s y s te m s , r un wa y c e n t r e
l i n e l i g h t s , and touchdown z on e l i g h t s .
3.4.6.2 F or a i r- t o -g r o un d o p e r a t i o n o nl y a r e c e i v e r an d de co d er a r e i n s t a l l e d on t h e
a i r p o r t . The a c t u a t i n g s i g n a l may b e p r ov i de d by a s p e c i f i e d s h o r t s e r i e s o f c l i c k s
a c co m pl i sh e d by k ey i n g t h e mi cr op ho ne o f a n a i r c r a f t c om m un ic at io ns t r a n s m i t t e r .
Ground-to-ground control i s u se d m os tl y when c a b l e c o n t r o l c i r c u i t s a r e n o t a v a i l a b l e
a nd a r e n o t p r a c t i c a l t o i n s t a l l . G ro un d- to -g ro un d c o n t r o l may b e u s e d o n l y t e m p o r a r i l y
u n t i l c a b l es c an be i n s t a l l e d o r p er m an en tl y e s p e c i a l l y t o r em ot e l o c a t i o n s .
3.5 LAMPS
? , 5 i l C h a r a c t e r i s t i c s ~ f i n ca x d es c e nt l a m p s
3.5.1.1 I n ca n de s ce n t lam ps a r e u se d i n most f i t t i n g s i n s t a l l e d i n ae ro dr om e l i g h t i n g
s y st em s . The f o l l o w i n g c h a r a c t e r i s t i c s of i n c a n d e s c en t la mp s a r e p e r t i n e n t t o t h e
d e s i g n of t h e a er od ro me l i g h t i n g c i r c u i t s .
3 .5.1.2 The l i g h t o u t p u t , l i f e , power co ns um ed , a n d e f f i c a c y ( e f f i c i e n c y ) of i n c a n -
descent lamps i s a c om pl ex f u n c t i o n of t h e a p p l i e d v o l t a g e o r c u r r e n t , a s i n d i c a t e d by
F igu re 3-8 and Table 3-1. For example , i f t he vo l t a ge app l i ed t o a lamp i s f i v e p er
c e n t g r e a t e r t h an r a t e d v ol t a g e , t h e l i g h t o ut p u t w i l l b e a b o u t 1 2 0 p e r c e n t o f r a t e d
l i g h t o u t p u t , and t h e lamp l i f e w i l l b e a b o ut o ne -h al f t h e d e s i g n l i f e . The e f f e c t s o f
c h an g es i n lamp c u r r e n t a r e g r e a t e r , I f t h e c u r r e n t t hr o u g h a lamp i s f i v e p e r c e nt
a bov e r a t e d c u r r e n t , t h e l i g h t o u t p ut w i l l b e a b o ut 1 3 5 p e r c e n t o f t h e r a t e d l i g h t o u t -
p u t , a nd t h e lamp l i f e w i l l be a b o ut t h r e e - t e n t h s t h e d e s i g n l i f e . T he se v a l u e si l l u s t r a t e t h e n eed f o r c l o s e c o n t r o l of t h e a p p l ie d v o l t a ge o r c u r r e n t .
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Tab le 3-1. Tab le of tamp Expon ents
o u t p u t - -OUTPUT
l i f e amperes 24.1- -L I FE [A.MPEmJ
wat t s amperes 2 .85- -WATTs [ m pE m , i
amperes -AMPERES
Note: C a p i t a l l e t t e r s r e p r e s e n t r a t e d v a l u es .
3.5.1.3 The de s i gne r of a n a er odr ome l i g h t i n g s y s t e m may ha ve some l a t i t u d e i n h i s
c h o ic e of lam ps f o r c e r t a i n ae ro dro me l i g h t f i x t u r e s , s e l e c t i n g a s e r i e s l am p, a low-
v o l t a g e m u l t i p l e l am p, o r a h i g h e r - v o l t a g e m u l t i p l e la mp . The f o l l o w i n g f a c t o r s are
p e r t i n e n t i n t h e c ho ic e:
a ) t h e v o l t a g e d ro p a cr o s s s e r i e s l amps u s u a l l y f a l l s i n t h e " lo w- vo lt ag e"
c a t e g o r y ; t h e v o l t a g e d r o p a c r o s s a 6.6 ampere, 200 wa tt runway edge
l i g h t i s 30 v o l t s , a nd t h e vo l t a ge d r op a c o r s s a 20 a m pe re , 500 w a t t
a pp roa c h l i g h t l amp i s 2 5 v o l t s ;
b ) b ec au se of t h e i r d i f f e r e n c e s i n d e s i g n t o l e r a n c e s , s e r i e s l am ps sh o u l d
n o t b e us ed i n p a r a l l e l c i r c u i t s , and m u l t i p le lam ps s h o ul d no'% be us ed
I n se r i e s c i r c u i t s ; and
c ) t h e l i f e of a " l o w- v o lt a g e" lamp w i l l b e g r e a t e r t h a n t h a t o f a "h igh-
v o l t a g e w * l am p, f o r a g i ve n r a t e d power c onsum pt i on and l i g h t ou t pu t .
-* " H i g h v o l t a g e " i s u se d i n t h i s s ec tr io n a s b e i ng t h e v o l t a g e
no r ma l l y u s e d f o r hous e ho l d l i gh t s .
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*z l4 0
m.5E3; 20
2.
F';,w* 3Z a
LY W
u n 80.(m
5
PER CENT NORMAL AMPERES
(a) SERIES TYPE LAMPS
PER CENT NORMAL VOLTS
(b) PARALLEL (MULTIPLE) TYPE LAMPS
Figure 3-8. E f f e c t s o f c u r r e n t a nd v o l ta g e v a r i a t i o n s o n
o p e r a t i n g c h a r a c t e r i s t i c s o f i n c a n d e s ce n t la mp s
3.5.1.4 Many lamps now be ing used f o r aerodrome l i g h t i n g
a r e t u n gs t e n- h a lo g e n l am ps . The f i l a m e n t s o f t h e s e la mp s a r e e n c l o s e d i n s m a l l q u a r t z
t u b e s w hi ch c o n t a i n s m a l l am ou nts of a h al o g en , s u c h a s i o d i n e , i n a d d i t i o n t o t h e u s u a l
i n e r t f i l l g a s. When t h e f i l a m e nt i s h e a t e d , t u n g s t e n e v a p o r a t e s f r om t h e f i l a m e n t a nd
condense s on th e in s id e wa l l s of th e lamp enve lope . The vapour i zed ha logen combines
w i t h t h i s co nd en se d t u n g s t e n f o r mi n g a v a po u r. T h i s v ap ou r t r a v e l s t o t h e h o t f i l a m e n t
where i t d i s a s s o c i a t e s an d r e d e p o s i t s t h e t u n g s t e n o n t h e f i l a m e n t . T hi s p ro c e s s
r e d u c e s b l a c k e ni n g o f t h e lamp bu l b , i n c r e a s e s t h e l i f e o f t h e l am p, m a i n t a i n s b e t t e r
l i g h t i n t e n s i t y , a n d i mp ro ve s t h e e f f i c i e n c y of t h e la mp . The c o s t of t h e la m ps i s
however increased .
3.5.2.1 The lamps use d i n
t h e s e q ue n c g e l i g h t s a n d n o t
in ca nd es ce nt lamps. The lamp i s a tube wh ich may be fo rmed i n t o va r i ous sha pes c on t a in -
i n g an i n e r t g a s s u c h a s a r g o n o r k r y p t o n w hi ch e m i t s l i g h t when a n a r c i s c r e a te d i n
t h e g a s . The power su p p ly c h a r g e s e l e c t r i c a l c a p a c i t o r s t o p r o v id e power f o r t h e a r c
and p rov ide s a t r i g g e r i n g v o l ta g e t o i n i t i a t e t h e a r c upon a p p l i c a t i o n o f t h e t r i g g e r i n g
s i g n a l . The a r c i n t h e g a s e m i ts a h i g h- i n te n sk t y f l a s h of i i g h t of s h o r t d u r a t i o n
( ~ c r o s e c o n d s )which r a p i d l y e xp en ds t h e ch a r ge of t h e c a p a c i t o r s a nd e x t i n g u i s h e s t h e
arc. Very h i g h voitages a r e P n v ~ i u e d o r t h e power s u p p l y and lamp. Th is h a z a r d s h o u l d
be c o n s l a e r e d i n ~ Z l edes ign of tlae i i g i ~ t i r ~ gysirem. The peak i i i t e i l s iC y uf ; k s e l ' ,gtits
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may be ve ry gre a t bu t o f s ho r t d u r a t i o n , The f l a s h must be i n t e g r a t e d t o de t er m in e t h e
e f f e c t i v e i n t e n s i t y o f t h e e mi t t e d l i g h t and i t s e f f e c t i v e n e s s a s a v i s u a l a i d . The
f re q ue n cy of f l a s h i n g o f t h e s e l i g h t s i s l i m i t e d by t h e t im e r e q u i r e d t o r e c h a r ge t h e
c a p a c i t o r s an d u s u a l l y i s on l y a f e w t i m e s pe r s e c ond . The o u t p u t o f t h e l i g h t i s pro-
p o r t i o n al t o t h e sq ua re of t h e vo l t a g e a p p li e d t o t h e l i g h t f i t t i n g , u n l e s s i t ha s a
r egula ted power supply .
3.5.2.2 . The h i g h e r e f f i c i e n c y o f g a s e o u s d i s c h a r g e
l am ps e nc ou r a ge s t h e i r u s e . T ypes o f t he s e la mps i nc l ud e f l uo r e s c e n t , m e rc ur y- va pou r,
m e t a l - ha l ide , a nd low- o r h i g h - p r e s s u r e s od i um - vapou r l i g h t s . The u s e o f l i g h t s of
t h e s e t y p e s i s u s u a l l y l i m i t e d t o i l l u m i n a t i o n of a r e a s s u ch a s a pr on a r e a s , e x ce p t f o r
t h e u s e o f f l u o r e s c e n t l am ps i n some t ax iw ay e d ge l i g h t s a nd f o r i l l u m i n a t i n g s i g n s .
When c o n s i d e r i n g u s i n g l i g h t s o f t h e s e t y p e s t h e f o l l o w i n g a r e f a c t o r s t h a t s h ou l d b e
i n v e s t i g a t e d .
a ) R e s t a r t i n e Some o f t h e s e l am ps c a n n o t b e r e s t a r t e d f o r s e v e r a l se c o n d
t o mi nu te s a f t e r t h e a r c i s e x t i n g u i s h ed . Power i n t e r r u p t i o n s o r
s w i t c h i n g c a n c a u se l o s s of l i g h t s a t c r i t i c a l t i m es . Emergency l i g h t -
in g by o th e r ty pes of l amps may be de s i r ab le .
b ) C ol d s t a r t i n g . Some o f t h e s e l am ps c a nno t be s t a r t e d o r a r e d i f f i c u l t
t o s t a r t i n l ow am bi en t t e m p er a tu r e s.
c ) I n t e n s i t y c o n t r o l . These l am ps o f t e n a r e n o t ca p a b le o f i n t e n s i t y c on -
t r o l o r h av e a l i m i t e d r an g e of c o n t r o l as compared t o incan desce nt
lamps.
d ) S t r o b o s c o p ic e f f e c t s . The s t r o b o s c o p i c e f f e c t s o f t h e l am p s may b e
d i s t u r b i n g . Where s u c h l i g h t s a r e u s ed , i n c l u d i n g f o r i l l u m i n a t i o n o f
a r e a s , t h e u s e of t h r e e -p h a s e e l e c t r i c a l s u p p ly sy s te m s w i t h a ba l a nc e
i n c o n n ec t i ng t h e l i g h t s may b e d e s i r a b l e .
e ) T y p i c a l l y t h e l i g h t e m i t t e d f ro m t h e s e l am ps c o ve r s al i m i t e d p a r t of t h e v i s u a l s pe ct ru m. T h i s makes r e c o g n i t i o n o f c o l o u r
c o d i ng d i f f i c u l t a s c o l o u r s may n o t h a ve t h e i r o r d i n a r y a p p ea r a nc e when
i l lu mi na te d by gaseous -d ischarge lamps . The co l our " r ed" i s par-
t i c u l a r l y a f f e ct e d .
3.6 METHODS OF OBTAINING INTEGRITY AND RELIABILITY FOR AERODROME LIGHTING
3 .6 .1 D e f i n i t i o ns o f t e r m s
3.6.1 .1 The t er ms i n t e g r i t y a nd r e l i a b i l i t y a s a p p l i e d t o a er od ro me l i g h t i n g a r e n o
p r e c i s e , e a s i l y d e f i n e d o r me asu re d te rm s. P re v io u s e f f o r t s t o d e f i n e t h e s e t erm s ha ve
c on cl ud ed t h a t r e l i a b i l i t y i s a qu es t i on of mean t ime be tween f a i l u r e of components
w h il e i n t e g r i t y i s a q u e s t i o n c o m p ri s i ng s u c h m a t t e r s as f a i l u r e s u r v i v a l o f t h e o v e r a l
sys tem. I t i s c o n si d e re d t h a t v i s u a l a i d s s h o u l d h av e a c om pa ra bl e i n t e g r i t y and r e l i a -
b i l i t y t o t h a t af f or d ed by n on -v is ua l a i d s . Thus r e l i a b i l i t y i s a f f e c t e d by t h e s e le c -
t i o n of c om pone nt s a nd op e r a t i o na l u s e , aiid i n t e g r l t j i i s a f f e c t e d by t h e d e s i g n an d
i n s t a l l a t i o n o f t h e s ys t e m s a nd m a i n te na nce o f t h e equ ipm en t . It i s d i f f i c u l t t o s t a t e
what t h e r e l i a b i l i t y of p resen t v i s u a l a i d s i s , I n g e n e r a l i t i s c o n s i d e r e d ch a t w e l l
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d e si g ne d an d m a in ta i ne d v i s u a l a i d s h av e a ve ry h i g h i n t e g r i t y a nd t h a t t h e p r o b a b i l i t yo f a f a i l u r e o c c ur r in g a t a c r i t i c a l moment i s e x t re m e ly low . N e v e r t h e le s s a l l r e as o n-
a b l e e f f o r t s s h ou l d be made t o i mp ro ve upon i n t e g r i t y an d r e l i a b i l i t y . E l e c t r i c a l f a c -
t o r s w hic h a f f e c t i n t e g r i t y and r e l i a b i l i t y may be c l a s s i f i e d as f o l l o w s :
a ) f a i l u r e of t h e c i r c u i t ;
b ) f a i l u r e o f t h e power s u p p l y ; a n d
c ) f a i l u r e of t h e c o n t r o l c i r c u i t .
3.6.2.1 R ed uc in g f a i l u r e of t h e c i r c u i t . A s t a nd a rd p r a c t i c e i s t o u s e s e v e r a l
c i r c u i t s t o p re v en t a f a i l u r e of one c i r c u i t b l ac k in g o u t a n e n t i r e l i g h t i n g s ys te m.
F ou r c i r c u i t s a r e s om et im es e mploy ed f o r l i g h t i n g t h e a p p r o a ch an d t h r e s h o l d . One
c i r c u i t i s u se d f o r t h e t h r e s h o l d l i g h t s an d t h r e e f o r t h e a p pr o ac h l i g h t i n g s ys te m.
The l a t t e r t h r e e c i r c u i t s a r e s o d es ig ne d t h a t i f one s ho ul d f a i l on ly e v er y t h i r d
b a r r e t t e would b e o u t of o p e r a t i o n . W here a l i g h t i n g p a t t e r n i s f e d by s e v e r a l
c i r c u i t s , t h e p r a c t i c e of e ac h c i r c u i t f e e d in g on e p a r t i c u l a r g e o g r ap h i ca l s e c t i o n of
t h e p a t t e r n i s n o t r ecom mended b e c a u s e l o s s o f o n e c i r c u i t c a n t h e n c h an g e t h e p a t t e r n
i n t o s om et hi ng e n t i r e l y d i f f e r e n t . F or ex am pl e, a n a p pr o ac h l i g h t i n g p a t t e r n c o m p ri s in g
a c e n t r e l i n e and f i v e c r o s s b a rs i f f e d i n two d i s t i n c t h a l v e s by two c i r c u i t s c o u l d
c han ge f r om a c e n t r e l i n e an d f i v e b a r s y s te m t o a c e n t r e l i n e an d t h r e e b a r s y s t em w i t h
t h e l o s s of o ne c i r c u i t .
3 .6 .2 .2 Reduc ing f a i l u r e o f th e power supp ly . S teps can be t aken t o en su re a con-
t i n u o u s s u pp l y o f power t o t h e l i g h t i n g s ys te m. h e of t h e m os t s im p l e an d m os t r e l i a -
b l e i s t o ha v e a l t e r n a t i v e s o u r c e s of power f r o m two d i f f e r e n t g e n e r a t o r s w h ic h a r e
c a p a b l e o f a u t o m a t i c a l l y s t a r t i n g i n c a s e o f a power f a i l u r e . E qu ip men t h a s b e e n d e ve l-
oped which w i l l r e d uc e t o a v er y s h o r t i n t e r v a l t h e t i me b et we en power f a i l u r e a nd d e l i -* - --"V C L ~ f c u r r e n t f ro m t h e a l t e r n a t i v e s ys te m. S w it ch in g r a t e s a s l o w a s 0=3 t o 0.5s ec on ds a r e b e i ng o b t ai n e d f o r e qu ip men t i n s t a l l e d i n c o n j u n c t io n w i t h p r e c i s i o n
a p p r oa c h r un wa ys . S w i t ch i n g r a t e s f o r o t h e r s y s te m s v a r y b e tw ee n 1 0 t o 20 s e c o n d s .
Another p roce dure which i s used i s t o o p e r a t e f r om t h e s e co n d a ry g e n e r a t o r s c o n t i n u o u s l y
d u r in g c r i t i c a l ti m es s u c h a s d u r i n g low v i s i b i l i t y c o n d i t io n s o r when a s t o r m i s
f o r e c a s t . I n c a s e of a f a i l u r e of t h e g e n e r a t o r , t h e s w i tc h - ov e r i s t h e n made t o t h e
p r imary power supp ly . These sys t ems and a r rangemen t s a r e d i s cus sed i n Chap te r 2.
3.6.2.3 So metim es a l t e r n a t e c o n t r o l c i r -
c u i t s a r e n e gl ec t ed . C a r ef u l a t t e n t i o n i s g iv en t o t h e l i g h t i n g c i r c u i t s a nd s e co nd ar y
power s u p p l i e s a r e p r ov i d ed f o r t he m, b u t pr ov i si on of a l t e r n a t e c i r c u i t s f o r c o n t r o ls
o f t h e l i g h t s f ro m t h e c o n t r o l to wer i s ove r looked . The p r o b a b i l i t y o f a c o n t r o l c i r -
c u i t f a i l i n g may be e q u a l t o t h a t of a l i g h t i n g c i r c u i t f a i l i n g , a nd du a l c o n t r o l
c i r c u i t s s h o u l d be p ro v id e d.
3.6.2.4 D es ig ni ng f o r i n t e g r i t y a nd r e l i a b i l i t y . The de s i g n and i n s t a l l a t i o n o f
a er od ro me l i g h t i n g s ys te ms c an a f f e c t i n t e g r i t y and r e l i a b i l i t y i n ways o t h e r t h a n
s e l e c t i o n of com ponents an d i n t e r l e a v i n g of c i r c u i t s . T hes e f e a t u r e s a r e o f t e n t h e same
a s t h o s e u s e d t o re d u ce a nd s i m p l i f y m a in t en a nc e . Some o f t h e f e a t u r e s d e t e r m i n e d i n
t h e d es i g n d e c i s i on s a r e i n s t a l l i n g c a b l e s i n c o nd u it ( d u c t s ) i n s t e a d of d i r e c t b u r i a l ,
u s i n g i n s e t l i g h t s i n s t e a d oE e l e v a te d l i g h t s i n a r e a s where s u r f a c e t r a f f i c o f t e n c ol -
l i d e s w i t h t h e l i g h t f i x t u r e s , p r ov id i ng g r ou nd -w ir e c i r c u i t s t hr ou gh ou t t h e s y st em t s
reduce t h e e f f e c t s of iigh~ning nd h i g h v o l t a g e s u r g e s , e qu ip pi ng l i g h t f i x t u r e s wkth
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con d i t i on occur s and does no t change any of t h e sys tems op e ra t i o ns . A human operator
must eva l u a t e t h e meani ng of t h e s i gn a l and t ake t he ap pro pr i a t e ac t i on . Examples of
p a s s i v e m o n i t o r i n g a r e t h e s e q u e n c e - f la s h i n g l i g h t s m o n it o r w hi ch a l e r t s when a
p re se l e c t ed number of l i g h t s i s i no pe ra t i v e , o r t he i nd i c a t o r l amp w hi ch show s t ha t
s p e c i f i c c i r c u i t s a r e e ne r g iz e d and o p e r a ti n g .
3 .7 .4 Monit o r ov e r r i de co n t r o l s
3.7.4.1 O ft en c o n t r o l s o r p r o c e d u r es wh i ch c an b e u s e d t o o v e r r i d e o r c i rc u m ve n t t h e
a c t i o n o f t h e m on it or a r e p ro v id e d. By a c t i v a t i n g a s p e c i a l c i r c u i t o r r e s e t t i n g a
c o n t r o l , t h e o p e r a t o r c a n m a i n t a i n t h e s y st e m s o p e r a t i o n w i t h o u t c h an ge f o r new o r
i n d e f i n i t e t i m e pe r i od . T he s i g n a l i n d i c a t i n g t h e m o n i t o r ' s r e s p o n s e may be provided
d u r i n g t h e o v e r r i d e o p e r a t i o n t o ke ep t h e o p e r a t o r i n fo rm ed t h a t t h e s y s t e m i s i n a n
u n d e s i r a b l e o p e r a t i n g s t a t u s . An example i s t o r e s e t t h e t im er t o f u l l i n t e n s i t y
o p e r a ti o n s a t t h e b eg in ni ng of e a ch ap pr oa ch i n low v i s i b i l i t y c o n d i ti o n s t o e n s u re t h a t
t h e l i g h t s w i l l n o t a u t o m a t i c a l l y b e ch an ge d t o a l ow e r i n t e n s i t y d u r i n g t h e a pp r oa c h.
3.8 ELECTRICAL CIRCUITS FOR RADIO NAVIGATION AIDS
3.8.1 T yp es of r a d i o n a v i g a t i o n a i d s
3.8.1.1 The t y p e s o f r a d i o n a v i g a t i o n a i d s w hi ch may b e l o c a t e d o n o r n e a r t h e
a er od ro me a n d r e q u i r e e l e c t r i c a l power e i t h e r f r om t h e a e ro dr om e power s y s t e m o r a s a
s e p a r a t e s y s te m v a r i e s w i t h t h e a e r od r om e . T hese r a d i o n a v i g a t i o n a l a i d s o f t e n i n c l u d e
i n s t ru m e n t l a n d in g s y s t e m ( I L S) , v e r y h i g h f r e q u en c y o m n i d i r e c t i o n a l r a d i o r a n g e (VOR),
non-d i r ec t i ona l beacon (NDB) , d i r e c t i o n f i n d in g (DF) f a c i l i t i e s , p r e c i s i o n a pp ro ac h
r a d a r s y s t e m s , d i s t a n c e m ea s u ri n g eq ui pm en t (DME), a i r s u r v e i l l a r ~ c e a d a r (ASR) , and
s i m i l a r e q ui pm e nt , Most aerodromes a r e equipped wi th some of th es e devic es and th e
e l e c t r i c a l power r e q ui r em e n ts may r e q u i r e s p e c i a l c o n s i d e r a t i o n . N ote t h a t t h e ILS f o r
c a t e g o r y I1 an d 111 o p e r a t i o n s i s more p r e c i s i o n e q ui pm en t t h a n t h a t r e q u i r e d f o r
c a t e g o r y I o p e r a t i o n s .
3.8.2 E l e c t r i c a l c h a r a c t e r i s t i c s
3.8.2.1 E l e c t r i c a l power f o r r a d i o n a v i g a t i o n a i d s i s u s u a l l y a l t e r n a t i n g c u r r e n t
( a c ) . B a t t e r i e s may be used t o p rov i de pow er f o r s t a r t i n g s econda ry power s our ces and
t o supp l y energy fo r some un i n t e r r up t i b l e power sys t ems . This a c power i s u s u a l l y
e i t h e r 50 o r 60 h e r t z .
3.8.2.2 P ri ma ry po wer. F or r a d i o n a v i g a t i o n a i d s l o c a t e d o n o r a d j a c e n t t o t h e
aerodrome, th e pr imary power sour ce i s us ua l l y t h e same a s t he ae rodrome p r i mary source .
'I'hese s o u r c e s a r e d i s c u s s e d i n p a r ag r a ph 2 .1 .2 , S i n ce t h e t o t a l k i l o w a t t s r e q u i r e d by
r a d i o n a v i g a t i o n a i d s u s u a l l y i s n o t l a r g e , t h e i n pu t power t o t h e s e i n s t a l l a t i o n s i so f t e n t r a n s mi t t ed a t t h e i n t e r m e d ia t e v o l t a g e l e v e l a nd f e d t o L oc al d i s t r i b u t i o n
t r a n sf o r m e rs f o r s tep -down t o t h e v o l t a g e s u i t a b l e f o r t h e e q ui pm en t,
3.8.2.3 S ec on da ry p ow er * S i n ce t h e s e r a d i o n a v i g a t i o n a i d s p r o v i d e s i g n a l s f o r
i n st r um e n t gu id an ce of t h e a i r c r a f t a nd a r e e s s e n t i a l f o r o p e r a t i o n s i n a t l e a s t some
condi t ions , Annex 10, Voiurne I , P a r t i , C'napter 2 r e qu i r e s s econda ry pow er ao in rces f o r
mos t o f t he se r ad i o a i ds . The sw i t ch -ove r t ime f o r some o f t he se r ad i o nav i ga t i on a i ds
a r e show n i n Tab l e 2-1 and d iscussed i n paragraphs 2 , 2 and 2 , 3 o f t h i s manua l. Ther a d i o navis--:a L L u u- a i d s a r e o f t e n l o ca t ed In .solated a r e a s o r a reas w e l l s e p a r a t e d f ro m
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o t h e r b u i l d i n g s r e q u i r i n g e l e c t r i c a l p ower. Secondary power i s u s u a l l y p r o v i d e d by
eng ine -ge ne ra to r power u n i t s because , f o r th e amount of power needed, seco ndar y power
may b e more ec o no m ic a l t o i n s t a l l t h a n a s ec o nd f e e d e r t o t h e s i t e . I f a n i n d e p e nd e n t
power source i s u se d, t h e f e e d e r f ro m t h i s s o u r c e s ho u ld b e i n a s e p a r a t e d u c t o r ev en a
s e p a r a t e r o u t e f r om t h e p r i m a r y power f e e d e r . Some o f t h e r a d i o n a v i g a t i o n a i d s a r e
m o r e l i k e l y t o r e q u i r e u n i n t e r r u p t i b l e p ower s u p p l i e s t h a n a r e a e ro dr om e l i g h t i n g
s y s t e m s . The re d u n da n t c o n f i g u r a t i o n o f F i g u r e 2- 3 i s o f t e n a d v i s a b l e f o r some r a d i o
n a v i g a t i o n a i d s a nd r e l a t e d c o m pu te rs .
3.8.2.4 Groundin@
S t a b l e g r ou n di n g t h a n
p a r a g r a p h 2 .5 .14 , a p p l
R ad io n a v i g a t i o n a i d s may r e q u i r e l o we r r e s i s t a n c e a n d mo re
do ae rodrome l i g h t i n g sys tems . The g round ing , as d i s c u s s ed i n
i e s b u t g r ou n di n g ne t wo r ks a r e m ore o f t e n r e q u i r e d . The grounding
r e qu i re m en t s o f b o th t h e e l e c t r i c a l sy st em a t t h e r a d i o a i d s b u i l d i n g a nd a t t h e a n t e n n
s h o u l d b e c on s i d e r e d c a r e f u l l y . Some o f th e an tenna s may re qu i r e sp e c i a l g round ing
p l a n e s i n some l o c a t i o n s . P r o t e c t i o n o f t h e gr o u n di n g s y s te m s f r o m c o r r o s i o n may b e
n e c e s s a ry f o r some r a d i o n a v i g a t i o n a i d s .
3.8.2.5 L i g h tn i n g a r r e s t e r s . L i gh t ni n g a nd s u r g e p r o t e c t i o n f o r r a d i o n av i g a t i o n
a i d s i s more i m p o r ta n t t h a n f o r most e l e c t r i c a l s ys te ms b e ca us e t h e r a d i o s i g n a l s a r emore e a s i l y a f f e c t e d , and an t en n as a r e o f t e n t h e t a r g e t o f l i g h t n i n g s t r i k e s . Pa ragraph
2.5 .12 d i s c u s s es l i g h t n i n g p ro t e ct i o n. A lso t h e s e r a d i o a i d s o f t e n u s e s o l i d - s t a t e
d e v i c e s w h ic h a r e v u l n e r a b l e t o v o l t a g e a nd power s u r g e s . O ft en b a t t e r i e s o r c o n v e r t e r
a r e us ed t o p ro v i d e d c power f o r t h e s o l i d - s t a t e d e v ic e s t o e l i m i n a t e o r r e du c e t h e
l i g h t n i n g a n d p ow er s u r g e p ro b le m s.
3.8.2.6 F e ed s t o a n t e n n a a r r a y s . The c a b l i n g b et w ee n t h e r a d i o eq u i p m en t a nd t h e
a n t en n a o f t e n r e q u i r e s s p e c i a l h a nd l in g . U su al ly c o a x i a l c a b l e s a r e u s ed t o co nd uc t
t h e s e s i g n a l s . The c a b l e may be r e q u i r e d t o p r o v i d e a p r o p e r i m pe da nc e m a t c h b et we en
t h e o u t p u t o f t h e s i g n a l g e n e r a t o r a nd t h e i n p u t t o t h e a n t e n n a b u t may a l s o n ee d t o b e
of a n a c c u r a t e l e n g t h f o r f r eq u e n cy p h a si n g. The r a d i o e qu ip me nt o f t e n e x p l i c i t l y
s t a t e s t h e s e c a b l i n g r e q u ir e m e nt s b u t some r a d i o a i d s may n o t f u r n i s h t h e s e d e t a i l s .
The feeds t o t h e a nt en n a a r r a y s s ho u ld be c a r e f u l l y c o o rd i n at e d w i th t h e s u p p l i e r of t h ee qu ip m en t an d t h e i n s t a l l e r s o f t h e a n t e nn a an d r a d i o e q ui pm en t.
3 .8 .3 ,1 Uses of c o n t r o l c i r c u i t s . The c o n t r o l c i r c u i t s f o r r a d i o n a v i g a t io n a i d s
a r e p r i m a r i l y u s ed t o e n e r g i z e and d e e n e rg i z e t h e s y st e ms , t o t r a n s f e r f r om pr im a ry t o
s ta nd -b y o r a l t e r n a t e t r a n s m i t t e r , a nd t o t r a n s f e r f ro m p ri ma ry t o s e c o n d ar y power
s o u r c e .3.8.3.2 The r a d i o n a v i g a t i o n a i d s may b e l o c a t e d o n t h e
a er od ro m e o r s e v e r a l m i le s away. Most r a d i o n a v i g a t i o n a i d s p r o v i d e l o c a l c o n t r o l a t
t h e t r a n s m i t t e r s i t e and r em ot e c o n t r o l a t o ne o r more a i r t r a f f i c o r e qu ip men t c o n t r o l
s i t e s . I f t h e r a d i o a i d s a r e l o c a t e d on o r n ea r t h e ae ro dr om e and t h e c o n t r o l s a r er e l a t i v e l y s im p le , a c o r d c power c o n t r o l c i r c u i t s s i m i l a r t o t h o s e u se d f o r a er od ro me
l i g h t i n g may be used . T he se c o n t r o l c i r c u i t s a r e d i s c u s s e d i n p a r a gr a ph s 3 . 4 . 1 . 4 ,
3 .4 .2 .3 , 3 .4 .3 .1 , and 3.4 .3 .2 a s gu i de s. If t h e d i s t a n c e s a r e g r e a t o r t h e c o n t r o l
c i r c u i t s a r e com plex, t e l ep h o n e c i r c u i t s a r e o f t e n u se d f o r re mo te c o n t r o l . By d i a l i n g
a p a r t i c u l a r c o de of o n e, tw o, o r t h r e e nu mb er s, t h e d e s i r e d s w i t c h i n g c a n be o b t a i n ed .
The t e l e p h on e d i a l i n g c o n t r c l s y s te m i s a form of m u l t i p l e x c o n t r o l wh ic h c a n be
e xp an de d f o r c o n t r o i l i n g v e r y c om pl ex sy s t em s .
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3.8.4 R e l i a b i l i t y and i n t e g r i t y o f r a d i o n a v i g at i o n a i d s
8.4.1 A s d i s c u s s e d i n p a ra g r ap h 3.6 .1 , t h e r e l i a b i l i t y an d i n t e g r i t y of n o n -v i su al
d s ( r a d i o n a v i g a t i o n a i d s ) s h o u ld be c om pa ra bl e t o t h a t of v i s u a l a i d s . I n a d d i t i o n
t h e e l e c t r i c a l f a c t o r s a f f e c t i n g aerodrom e l i g h t i n g of f a i l u r e of t h e c i r c u i t ,
f a i l u r e of t h e power s u p pl y , and f a i l u r e of t h e c o n t r o l c i r c u i t , t h e r a d i o n a v i g a t i o n
a i d s m u s t t r a n s m i t a s i g n a l h av in g s e v e r a l q u a l i t i e s w i t h i n a c c e p t a b l e t o l e r a n c e s .
T he se s i g n a l q u a l i t i e s a nd t o l e r a n c e s f o r t h e s e a i d s a r e d i s c u s s e d i n Annex 1 0 , Volume
I , P a r t 1 , C h ap t er 3. Not on ly must t he equipmen t be ope r a t in g and t r a ns mi t t in g a
s i g n a l , b ut i t s h o ul d be m o ni t or e d t o a s s u r e an a c c e p t a b l e s i g n a l . U s u a l l y n o s i g n a l i sp r e f e r a b l e t o a bad s i g n a l . To i mp ro ve r e l i a b i l i t y many r a d i o n a v i g a t i o n a i d s ha v e
a l t e r n a t e t r a n s m i t t e r s e n er g i ze d and r e a dy f o r s w i t c h in g t o t r a n s m i s s i o n upon f a i l u r e of
t h e p r im a ry t r a n s m i t t e r o r of a d e f i c i e n t s i g x a l . The r a d i o n a v i ga t i o n a i d s o f t e n h av e
in d i v i du a l seconda ry power s ou rce s t o au to ma t i ca l ly assume power i f t he p r imary power
s o u r c e f a i l s . The c o n t r o l sy st em s h ou ld be d es ig ne d s o t h a t i f t h e c o n t r o l s ho u ld f a i l
when t he a i d i s b e i n g o p e r a t e d by r em ot e m an ua l c o n t r o l , t h e r a d i o a i d w i l l remain
o p e r a t i n g an d s w i t c h t o a u t o m a t i c c o n t r o l . A tt ac hm en t F t o P a r t I of Annex 10 c o n t a i n s
a d d i t i o n a l g ui da nc e m a t e r i a l r e g a r d in g r e l i a b i l i t y and a v a i l a b i l i t y of r a d i o na v i g a ti o n
a i d s .
M o ni to r in g of r a d i o n a v i g a t i o n a i d s
3 .8 .5 .1 S i g n a l m o n i t o r i ng . The m o n i t o r i ng of r a d i o n a v i g a t i o n a i d s , e x c e p t f o r
l i g h t s t o i n d i c a t e t h a t t h e eq uip me nt i s e n e r g i z e d , r e q u i r e s a u t o m a t i c s e n s o r s of t h e
s i g n a l t o d et er m in e i f i t i s a c c e p t a b l e . S e v e r a l q u a l i t i e s of t h e s i g n a l and f u n c t io n -
ing of s ec t i on s of th e equipmen t may re qu i r e mon i to r ing . The mon i to r ing of t he s i gn a l
q u a l i t y f o r t h e s e r a d i o a i d s a r e d i s c u s s e d i n Annex 1 0 , Volume I , P a r t 1, C h a p t e r 3 .
The monitor may be r e q u i re d t o a u t o m a t i c a l l y s w it ch t o t h e a l t e r n a t e t r a n s m i t t e r o r
d e a c t i v a t e t h e e qu ip me nt and a l s o s i g n a l t h e d e s i g n a te d c o n t r o l p o i n t s of t r a n s m i t t e d
s i g n a l d e f i c i e n c i e s . O t he r l e s s e s s e n t i a l r a d i o n a v i g a t i o n a i d s may h av e m o n it o r s w hich
i n d i c a t e a t t h e c o n t r o l p o i n t s i f o p er a ti o n i s s a t i s f a c t o r y , I f i t i s n ot s a t i s f a c t o r y ,+-L.-l l =
o p e r a t o rcan
make th e r e qu i re d t r a n s f e r s , F or t h e r a d i o a i d s w it h c r i t i c a l s i g n a lr e q u i r e m e n t s , t h e m o n it o r may a u t o m a t i c a l l y d e a c t i v a t e t h e e qu ip m en t t o p r e v e n t t r a n s -
m is si on o f a d e f i c i e n t s i g n a l i f a s a t i s f a c t o r y s i g n a l fro m a n a l t e r n a t e t r a n s m i t t e r is
n o t o b t a i n e d .
3 .8 .5 .2 M o n i to r i ng a u x i l i a r y f u n c t i o n s . S e v e r a l o t h e r f u n c t i o n s may be moni to red t o
a s s u r e s a t i s f a c t o r y o p e r a t i o n of r a d i o n a v i g a t i o n a i d s . T he se may i n c l u d e b a t t e r y
v o l t a g e s f o r t h e s t a r t i n g of t h e s e co nd a ry power s e t o r f o r o p e r a t i n g u n i n t e r r u p t i b l e
power s u p p l i e s , a m bi e nt o r room t em p e r a t u r e t o m a i n t ai n s u i t a b l e e n v i r on m e n ts f o r t h e
equ ipmen t , and f u e l supp ly fo r th e seconda ry power sou rce . These mon i to r s may p rov ide
a la r ms o r i n d i c a t i o n s t h a t t h e f u n c t i o n s e xc ee d e s t a b l i s h e d c r i t e r i a .
3.9 ACCEPTANCE TESTING OF AERODROME ELECTRICAL CIRCUITS
3 .3 .1 .2 The t e s t p r o ce d u re s d e s c r i b e d i n t h i s s e c t i o n a p p l y t o t h e a c c e p ta n c e t e s t s
of new i n s t a l l a t i o ns and shou ld be per formed be fo re mak ing th e sys t em op e r a t i on a l .
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3.9.2.1 Each i n s t a l l a t i o n c o n t r a c t s h o ul d i n c l u d e a g u a r a n t e e c l a u s e s p e c i f y i n g a
p e r i o d of a t l e a s t on e y e a r d u r i n g w hi ch t h e i n s t a l l i n g c o n t r a c t o r c an be h e l d r e s p o ns i -
b l e f o r r e p a i r i n g and r e p l a c i n g a l l c a b l e an d e qu ip me nt f a i l u r e s r e s u l t i n g f r om p oo r
w or k o r d e f e c t i v e m a t e r i a l s a nd e qu ip m en t. (Damp o r d i r t y c a b l e c o n n e c t o r s a n d c a b l edamage d ue t o f a u l t y i n s t a l l a t i o n p r a c t i c e s o f t e n f a i l s e v e r a l months a f t e r
i n s t a l l a t i o n . )
3 .9 .3 .1 V i s u a l e x a m in a t io n . The m ost i m p o r t a n t o f a l l i n s p e c t i o n a nd t e s tp r o c ed u r es a r e t h or o ug h v i s u a l i n s p e c t i o n s . V i s u a l i n s p e c t i o n s s h o ul d be made
f r e q u e n tl y d u ri n g i n s t a l l a t i o n , a t co m pl et io n o f i n s t a l l a t i o n , a nd b e f or e e n e r g i z i n g t h e
c i r c u i t s . A c a r e f u l v i s u a l i n s p e c ti o n w i l l r e v e a l d e f e c t s t h a t c an be c o r r e c t e d p r i o r
t o a c ce p t an c e t e s t s and e n e r g i z a t i o n . S e r i o u s damage may o c c u r i f d e f e c t s a r e s u b j e c t e d
t o e l e c t r i c a l t e s t s o r en e r gi z a ti o n . V i su a l i n s p e c ti o n s s ho ul d i n c l u d e i n s p e c t i o n
a p p r a i s a l o f :
a ) c o r r e c t n e s s of e x t e r n a l c o n n e c t io n s ;
b ) good work perf orm ance ;
c ) c l e a n li n e s S ;
d ) s a f e t y h a z ar d s ; an d
e ) s p e c i f i c r eq u ir e me n ts f o r i n d i v i d u a l i t e m s .
A l l e q ui p me n t m an u fa c tu r ed u n d e r s p e c i f i c a t i o n s s ho ul d p as s s t r i c t f a c t o r y t e s t s p r i o r
t o sh i pm e nt , b u t i t s h o u l d be v i s u a l l y i n s p e c t e d f o r s h i p p i n g dam age i m m e d i a t e l y upo n
r e c e i p t .
3.9.3.2 . The primary and
s ec o nd a ry c a b l e l e a d s of t h e t r a n sf o r m e r s s h o ul d b e s u p p l i e d w i t h f a c t o r y i n s t a l l e d
m olded c o n n e c t o rs . V i s ua l i n s p e c t i o n o f t h e s e i t e m s d u r i n g i n s t a l l a t i o n i s e s p e c i a l l y
i m p o r t a n t , a s min or c u t s , b r u i s e s , o r m i sh a nd l in g may r e s u l t i n a p r o g r e s s i v e
d e t e r i o r a t i o n w hic h w i l l e v e n t u a l l y c au s e c o mp l et e f a i l u r e , b u t n o t u n t i l some ti m e
a f t e r a c c ep t a nc e t e s t s . D ur in g i n s t a l l a t i o n , t h e s e i t em s s h o ul d b e i n s p e c t e d t o
d e t er m i n e t h e f o l l o w i n g :
a ) t h a t t h e m a t in g s u r f a c e s o f m o ld ed c o n n e c t o r s a r e c l e a n a nd d r y when
p lu gg ed t o g e th e r . I f c l e a n a nd d r y i n s i d e , t h e s e h i g h v o l t a g e
c o nn e ct o rs w i t h t a p i n g f or m a c o n n e ct i on e q u a l t o , o r s u p e r i o r t o , a
c o n ve n t io n a l h i g h v o l t a g e s p l i c e . C on ve rs el y, i f t h e y a r e w et o r d i r t y
i n s i d e , n o am ou nt of t a p i n g ca n p r o d uc e a s a t i s f a c t o r y c o n n e c t i o n . Two
o r t h r e e t u r n s of t a p e a r e recom mended t o h o l d t h e c o n n e c t o r t o g e t h e r
a nd k e ep t h e p a r t i n g l i n e s c l e a n . C l e a n l i n e s s o f ma t in g s u r f a c e s ca n
b e s t be i n s u r ed by k ee pi ng t h e f a c t o r y i n s t a l l e d c a p s i n p l a c e u n t i l t h e
f i n a l c o n ne c ti o n i s made. The mati ng su rf ac es of uncapped co nn ec to rs
shou ld no t be l a i d down, touched , o r b rea thed upon . I f i t i s n e c e s s a r y
t o b re a k a connec t ion , th e conn ec to r s shou ld be immedia te ly capped ;
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5-5 6 Aerodrome Desirrn Manual
b ) t h a t t h e c o n ne c t or s a r e c o mp l et el y p lu gg ed t o g e t h e r . A f t e r i n i t i a l
p l u g gi n g , t r a p p e d a i r p r e s s u r e may p a r t i a l l y d i s en g a ge t h e p l u g an d
r e c e p t a c l e . I f t h i s ha pp en s, w a i t a few seconds and push them toge th e r
a g a i n . A pply two o r t h r e e t u r n s o f t a p e t o h o l d them i n p l a c e ;
c ) t h a t t h e c a b l e s h a ve n o t b ee n c u t by s h o v e l s , k i n k ed , c r u sh e d byv e h i c l e w h e e l s , b r u i s e d b y r o c k s , o r damaged i n an y way d u r i n g h a n d l i n g
a nd i n s t a l l a t i o n ;
d ) t h a t t h e c a b l e s a r e b u r i ed t o t h e s p e c i f i e d d e p t h below f i n i s h e d g r a d e
and a l l o t h e r d e t a i l e d r eq ui re me nt s of t h e i n s t a l l a t i o n s p e c i f i c a t i o n
a r e a c c o m p l i s h e d ;
e ) t h a t t h e c a b l e s d o n o t d i r e c t l y c r o s s e a c h o t h e r a nd a r e s e p a r a t e d by
t h e r eq u i r e d d i s t a n c e s ;
f ) t h a t s c r e e n e d m a t e r i a l h a s b ee n pl a c e d u n de r a nd o v e r t h e c a b l e s , a nd
t h a t r o c k s o r p eb b le s d o n o t c o n t a c t t h e c a b l e s ; and
g ) t h a t t h e c a b l e s h a ve n o t b ee n b e n t s h a r p l y w her e t h ey e n t e r ( o r l e a v e ) a
c o n d u i t a nd a r e s u p p o r t e d p r o p e r l y by t amped g r ou nd , s o f u t u r e s e t t l i n g
c a n no t c a u s e s h a r p b e n ds .
3 .9 .3 .3 C o n s t a n t - c u r r en t r e g u l a t o r i n s p e c t i o n . E ach c o n s t a n t - c u r r e n t r e g u l a t o r
s h o u ld be i n s p e c t e d t o e n s u r e t h a t p o r c e l a i n b us h in g s have no t been c racked , no sh ipp ing
damage h a s o c c u r r e d , c o n n e c t io n s a r e c o r r e c t , s w i t c h e s an d r e l a y s o p e r a t e f r e e l y a nd a r e
n o t t i e d o r b lo ck ed , f u s e s ( i f r e q u i r e d ) a r e c o r r e c t , and t h a t t h e o i l l e v e l o f o i l -
f i l l e d r e g ul a to r s i s c o r r e c t . Only r e l a y p a n e l c o v e r s s h o u l d b e removed f o r t h i s
i n s p e c t i o n . It i s n o t n e ce s s ar y t o op en t h e main t a n k of o i l - f i l l e d r e g u l a t o r s .
I n f o mr a t io n on t h e r e g u l a t o r i n s p e c t i o n p l a t e mus t b e f o l lo w e d. All c o v e r s s h o u l d b e
c le a ne d and t i g h t l y r e p la c ed a f t e r i n s p e c t io n and t e s t s a r e completed.
3.9.3.4 An i n sp ec t io n shou ld be made t o
d e te r mi n e t h a t t h e c o l ou r , q u a n t i t y , and l o c a t i o n s of l i g h t s a r e i n ac c or d an c e w i t h t h e
i n s t a l l a t i o n d ra wi ng s. Each l i g h t s h o ul d be i n s p e c t e d t o d e te r m i ne t h a t i t i s o p e r a b l e ,
t h a t g l a s s i s n o t b ro ke n o r c ra c ke d, t h a t c o r r e c t iam ps a r e i n s t a l l e d , a nd t h a t -i t has
been p ro pe r ly l ev e l ed and a imed .
3 .9 .3 .5 In sp ec t io n o f misc e l l an eous componen ts . Components such a s c o n t r o l pa ne l s ,
r e l a y c a b i n e t s , p a n e l b o a r d s , e t c . , s h o u ld be v i s u a l l y i n s p e c t e d f o r damage, c o r r e c t
c o n n e c t io n s , p r o p e r f u s e an d c i r c u i t - b r e a k d e r r a t i n g s , a nd co m pl ia nc e w i t h t h e
i n s t a l l a t i o n d r aw in gs .
3 .9 .3 .6 S ys te m o p e r a t i o n t e s t . A f t e r c om po ne nt s a nd c i r c u i t s h a v e b e en i n s p e c t e d ,
a s i n d i c a t e d i n t h e p r e ce e d in g pa r ag r a ph s , t h e e n t i r e s y s te m s h ou l d be r e s t e d a s
f o l l o w s :
a ) e a c h s w i t c h of t h e l i g h t i n g p a ne l s i n t h e c o n t r o l to we r s ho u l d b e
o p e ra t ed s o t h a t e a ch s w i tc h p o s i t i o n i s r e ac h ed a t l e a s t t w i c e , D ur in g
t h i s p r o c e ss , a l l L i g h t s an d v a u l t e qu ip m en t s h o u l d b e o b se r v e d t o
d e te rm i ne t h a t e a ch s w it c h pr o p er l y c o n t r o l s t h e c o r re s p o nd i n g c i r c u i t ;
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P a r t 5. - E l e c t r i c a l S v s t e m s 5-57
b ) t h e ab ov e t e s t s ho ul d be r ep e at e d u s i n g t h e p a ne l s i n t h e a l t e r n a t e
c o n t r o l s t a t i o n ( v a u l t ) and t h e n r e p ea t ed a g a i n u s i n g t h e l o c a l c o n t r o l
s w i tc h es o n t h e r e g u l a t o r s ; a nd
c ) e ac h l i g h t i n g c i r c u i t s h o u ld b e t e s t e d by o p e r at i n g i t c o nt i n uo u s ly a t
maximurn i n t e n s i t y f o r a t l e a s t6
h o u rs . V i s u a l i n s p e c t i o n s h o u l d b emade a t t h e b eg in ni ng and a t t h e e nd of t h i s t e s t t o d et er mi ne t h a t t h e
c o r r e c t num ber of l i g h t s are o p e r a t i n g a t f u l l i n t e n s i t y . Dimming o f
some o r a l l of t h e l i g h t s i n a c i r c u i t i s a n i n d i c a t i o n o f g ro un d
f a u l t s . I n a d d i t i o n , t h e l a m p- t e rm i n al v o l t a g e s h o u l d b e m ea su re d o n a t
l e a s t o ne l i g h t t n ea ch m u l t i p l e c i r c u i t , t o de te rm in e t h a t i t i s w i t h i n
t 5 p e r c e n t o f t h e r a t e d l a mp v o l t a g e a s ma rk ed o n t h e l a mp .
3.9.4 E l e c t r i c a l t e s t s o f s e r i e s - c i r c u i t e q ui pm en t
3.9.4.1 E l e c t r i c a l t e s t s a r e h e l p f u l i n de te rm in in g t h a t t h e q u a l i t y o f t h e i n s t a l -
l a t i o n i s a c c e p t a b l e a nd t h a t t h e p er f or m an c e w i l l m ee t t h e o p e r a t i o n a l r e q u i r e m e n ts .
Some of t h e t e s t s i n v o l v e t h e u s e a nd m ea sur em en ts o f h i g h v o l t a g e c i r c u i t s . T hes e
t e s t s s h o u l d be p e rf or me d o n l y by q u a l i f i e d p e r s o n s who a r e f a m i l i a r w i t h h i g h - v o l t a ge
e l e c t r i c a l e q ui pm en t an d t h e s a f e t y p r e c a u t i o n s w hi ch m ust b e o b s e r v ed .
3.9.4.2 E l e c t r i c a l t e s t s on c a b l e . C ab le s b u r i e d i n e a r t h ( t h a t i s , n o t i n d u c t )
s h ou l d b e t e s t e d b e f o r e and a f t e r b a c k f i l l i n g t h e c a b l e t r e n ch .
3.9.4.3 Each s e r i e s c i r c u i t s h o u l d b e t e s t e d f o r c o n t i n u i t y by ohmmeter o r e q u i -
v a l e n t m ethod. The r e s i s t a n c e o f t h e c i r c u i t t o g ro un d s h o u l d t h e n b e c he c ke d w i t h a
s u i t a b l e t e s t s e t t o make s u r e i t i s f r e e o f g r ou n ds . Any f a u l t s i n d i c a t e d by t h e s e
t e s t s s h o u l d b e l o c a t e d an d r e p a i r e d b e f or e p r o ce e di n g w i t h h ig h -v o lt a ge t e s t s .
3.9.4.4 Each s e r i e s c i r c u i t s ho ul d be s u b je c te d t o h i g h v o l t a g e i n s u l a t i o n r e s i s t -
a n c e t e s t s t o de t e rm i n e c om p le t f r ee d om f r om g r ou n ds . Whenever p o s s i b l e , t h e s e t e s t s
shou ld be performed when t h e ground i s t h o r o u g h l y w e t. E x p e r i e n c e h a s sh own t h a t c i r -
c u i t s w hich p as s i n s u l a t i o n r e s i s t a n c e t e s t s d u r in g d ry w ea th er may f a i l a f t e r a heavy
r a i n . Each c i r c u i t , i n c l u d i n g t r a n s f o r me r s , s h o u ld be t e s t e d a s f o l l o w s :
a ) M s co n il ec t b o t h l e a d s f ro m t h e r e g u l a t o r o u t p u t t e r m i n a l s . S u pp o rt b o t h
l e a d s s o t h a t a i r ga ps of s e v e r a l in c h es e x i s t b e tw ee n b a r e c o nd u c to r s
and ground. Make s u r e t h a t t h e c a b l e s h e a t h i s c l e a n an d d r y f o r a
d i s ta n ce of a t l e a s t 30 cm f rom th e end o f t he cab le . A l so make s u r e
t h a t e x po se d i n s u l a t i o n a t e ac h e nd of t h e c a b l e i s c l e a n a n d d r y .
b ) Each c i r c u i t s ho u l d b e t e s t e d i mm ed ia te ly a E t e r i n s t a l l a t i o n , i n a c co r d-
a n c e w i t h " F i r s t T e s t F o r New C i r c u i t s " d e s c r i b e d i n s ub - p ar a g ra p h e ) .
Any c i r c u i t which h a s bee n i n s t a l l e d f o r 60 d a y s o r m or e, e v e n i f i t h a s
n o t b e en o p e r a t e d , s h o u l d b e t e s t e d i n a c c o r d a n ce w i t h " S u c c e ed i n g T e s t
and Old Ci r cu i t s ". ( S e e s u b - p a r a g r a p h e ) . )
c ) The maximum ac ce p t ab le l e akage cu r r en t , i n mic roampere s , s hou ld no t
e xc ee d t h e v a l u e s i n d i c a t e d i n pa r a gr a p h 3.9 .4 .7 .
d ) When a d d i t i o n s a r e made t o o l d c i r c u i t s , o n l y t h e new s e c t i o n s s h o u l d b e
t e s t e d i n a cc o rd a nc e w i t h " F i r s t Tes t On New Ci rc u i t s " . The comple te
c i r c u i t s h ou l d be ch ec ke d a t t h e r ed uc ed v o l t a g e s t o e n s u r e r e l i a b l e
o p e r a t on.
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3.9.5.4 C o a x i a l c a b l e s . R ad io f r eq u en c y c a b l e s s h ou l d be t e s t e d f o r i n s u l a t i o n a nd
l oo p r e s i s t a n c e p r i o r t o i n s t a l l a t i o n an d t h e r e s u l t s r ec or de d. The i n s u l a t i o n t e s t
shou ld be made be tween th e ce n t re conduc to r and sh i e l d wi t h a 5 0 0 v o l t d c i n st r u m en t .
The l o op r e s i s t a n c e t e s t s h o u l d be a l s o made a s a b ov e, b u t w i t h t h e c e n t r e c o n d u c t o r s
s h o r t e d t o t h e s h i e l d a t t h e f a r en d o f t h e c a b l e . T hi s t e s t may be made w i t h a b r i d g e ,
ohm meter, o r o t h e r s u i t a b l e i n s t r u m e n t. A f t e r i n s t a l l a t i o n , t h e c o n d uc t o r- t o -s h ie l d a ndconduc to r- to -grond re s i s t an ce shou ld exceed 5 0 megohms when mea sur ed a t 5 0 0 v o l t s d c .
Loop r e s i s t a n c e s h o u l d be w i t h i n p l u s o r m in us 1 0 p e r c e n t o f t h e me as ur ed v a l u e s p r i o r
t o i n s t a l l a t i o n , e.g. m ea su red r e s i s t a n c e p e r 1 0 0 0 m e tr es of c a b l e o n r e e l , m u l t i p l i e d
by each 1 0 0 0 m e tr es and f r a c t i o n t h e re o f of i n s t a l l e d c a bl e . S h i e l d - t o g ro un d r e s i s t -
a n c e sh o u l d a l s o b e me as ur ed a n d t h e r e s u l t s r e c o r d e d .
3 . 9 . 5 . 5 C o a x ia l c a b l e , p r e s s u r i z e d . Upon c o m p le t i on o f t h e c a b l e i n s t a l l a t i o n , t h e
f o l l o w i n g t e s t s h o u l d be made:
a ) E l e c t r i c a l t e s t . A h i g h - v o l t a g e i n s u l a t i o n t e s t e r w i t h m ic ro am me te r
cur re n t - l eakag e me te r shou ld be used and 3 0 0 0 v o l t s d c a p p l i e d b etw ee n
t h e i n n e r a nd o u t e r c o n d u c t o r s f o r a minimum p e r i o d o f t h r e e m i n u t es .
W hil e t h i s v o l t a g ei s
a p p l i e d no n o t i c a b l e c u r r e n t s h o u l d f l o w bet we ent h e c o nd u ct or s a f t e r c h a r gi n g c u r r e n t h a s s t a b i l i z e d .
b ) N it ro ge n g a s t e s t . N it ro ge n g a s a t t h e s p e c i f i e d p r e s s u r e s h o u l d b e
a p p l i e d t o t h e c a b l e , t h e g a s v a l v e c l o s e d , and a mb i en t t e m p e r a t u r e
r e c o r d e d . S i x s u c c e s s i v e , h o u r l y me as ur em en t o f p r e s s u r e s h o u l d b e
t a k e n a nd r ec o r de d . A f t e r t h e s i x t h m ea su re me nt i s t a k en an d a f t e r a
t i me i n t e r v a l o f a b ou t 2 4 hou rs , a sev en th measurement sh ou ld be made.
I f v a r i a t i o n s i n g a s p r e s s u r e a r e d ue on l y t o c h an ge s i n a m bi e n t te mp er -
a t u r e , t h e l e n g t h of c a b l e i s a c c e p t a b l e . A t e m p er a t ur e c o r r e c t i o n
f a c t o r of 0.017 p e r d e g r e e C should be used.
3,9,6.X ' fi e s up p l y v o l t a g e a nd t h e i n p u t t a p o f t h e r e g u l a t o r s h o u l d he c h ec ke d t o
s e e t h a t t h e y c o r re sp o nd .
3.9.6.2-.w r t h l o a d d i s c o n n e c t e d , e n e r g i z e t h e r e g u l a t o r o n c e , a n d w a tc h t h e o pe n-
c i r c u i t p r o t e c t o r t o s e e t h a t i t d e e ne r g iz e s t h e r e g u l a t o r w i t h i n 2 o r 3 seconds .
a ) Connect t h e lo a d c i r c u i t a f t e r i t ha s been checked f o r opens and g round
a s r e q u i r e d i n p a r ag r ap h s 3.9.4 .3 and 3 . 9 . 4 . 4 and i n s p e c te d t o s e e t h a t
a l l t r a ns f o rm e r s a r e p r o p e r l y l an p ed .
b ) Obta in a vo l tm e te r and an ammete r w i t h an e r r o r of n o t more than L 1 p e r
c e n t o f f u l l s c a l e , a nd s i m u l t a n eo u s l y m ea su re i n p u t v o l t a g e a nd o u t p u t
c u r r e n t ( c o nn e c t t h e ammeter t o t h e t e r m i n a l s o f a n i s o l a t i n g t r a n s fo r m -
e r i n se r t e d i n t o th e o ut pu t c i r c u i t of t h e r e g u l at o r ) f o r e a ch i n t e n s i t y
s e t t i n g t ap .
c ) Use a r e c o r d i n g v o lt m e t e r o r t a k e r e a d i n g s d u r i n g b ot h da y a nd n i g h t a t
s u f f i c i e n t i n t e r v a l s t o o b t a i n a n av e ra g e su pp ly v o l t ag e .
d ) I f r e g u l a t o r h s s i n p u t v o l t a g e t a p s , s e l e c t t h e t a p w h i c h mos t nea r ly
c o r r e s p o n d s t o a v e r a g e s u p p l y v o l t a g e . The o u t p u t c u r r e n t f o r e a c h
i n t e n s i t y s e t t i n g t a p s h o u l d be wfchfn IL 2 p e r c e n t o f t h e n a m e pl a te
v a l u e s a f t e r any necessa ry s u p p l y v o l t a g e c o r r e c t i o n i s made.
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3 .9 .6 ,3 I n a l l c u r r e n t r e g u l a t o r s w hich hav e in p u t v o l t a g e t a p s , t h e o u t p u t c u r r e n t
w i l l v a ry i n p r o p o r t io n t o i n p u t v o l t a g e c ha ng es . I f a s u p pl y v o l t a g e o f 2 3 5 0 i s
a p p li e d t o t h e 2 4 0 0 v o l t t a p , t h e o u t p u t c u r r e n t v a l u e s sh o u l d b e 2 p e r c e n t b elo w t h e
namepla te va lues .
3.9.6.4 R e gu l at o rs w hic h h av e a u to m a t ic s u pp l y v o l t a g e c o r r e c t i o n i n l i e u o f i n p u t
t a p s d o n o t ch an ge t h e o u t p u t c u r r e n t a s t h e s u p pl y v o l t a g e v a r i e s .
a ) I f t h e o u t pu t c u r r e n t o n f u l l i n t e n s i t y d e v i a t e s f ro m t h e n a m e pl at e
va lu e by more than 2 p e r c e n t ( and i f t h e r e g u l a t o r i s n o t o v e r l o a d e d ) ,
t h e i n t e r n a l a d j us tm e n t s h ou l d be c h ec ke d, a s d e s c r i b ed o n t h e r e g u l a t o r
i n s t r u c t i o n p l a t e . S i n c e t h e a d j us t m e nt may b e d e l i c a t e , i t i s
recommended th a t a de v i a t io n o f +- 5 p e r c e n t h e a l lo w e d o n l ow e r s e t -
t i n g s b e fo r e a t t e m t i n g t o r e a dj u s t t h e r e g u l a t o r .
b ) F u r t he r m o r e, a c h e c k s h o u l d be made t o s e e w h e th e r t h e a d j u s t m e n t h a d
b ee n ch an ge d p u rp o se l y f o r a n u nu s ua l l o c a l f l i g h t o p e r a t i o n a l
requ i remen t .
3.9.7.1 The f ol lo wi ng t e s t s h o ul d h e l p l o c a t e t h e f a u l t i n t h e e v e n t t h a t t h e t e s t s
i n d i c a t e i m p ro p er o p e r a t i o n.
3.9.7.2 D is co nn ec t t h e l o a d , s h o r t - c i r c u i t r e g u l a t o r o u t p u t t e r m i n a l s t h r o u gh a n
a mm et er , an d m ea su re o u t p u t c u r r e n t . I f m ea su re d v a l u e s a r e e q u a l t o o r s l i g h t l y h i g h e r
t h a n n a me p la t e v a l u e s , t h e r e g u l a t o r i s o p er a ti n g s a t i s f a c t o r i l y and t h e l o a d c i r c u i t
s h o u l d b e ch ec ke d f o r f a u l t s .
3.9.7.3 C onn ect t h e l o a d c a b l e s ( a f t e r l o a d c i r c u i t h a s b ee n ch ec ke d f o r o p en s an d
g ro un ds , a s s p e c i f i e d i n p a ra g ra p hs 3.9 .4 .3 an d 3.9.4.4 and i n sp e ct e d t o s e e t h a t a l l
t r a n s f o r m e r s a r e p r o p e r l y l a mp ed ), a nd me as ur e o u t p u t c u r r e n t a nd o u t p u t v o l t a g e
s i m u l t a n e s us l y w i t h t h e regulator o pe ra ci ii g on i h e h i g h es t i n t e n s i t y s e t t i n g . The
s i g n i f i c a n c e o f t h e r e a di n g s i s a s f o l l o w s :
a ) S a c i s f a c to r y o p e r a t i o n i s i n d i c a t e d by c o r r e c t o u tp u t c u r r e n t a nd a n
o u t p u t v o l t a g e w h ic h i s s l i g h t l y h i gh e r t ha n t h a t e s t i m at e d f o r t h e
l o a d , b u t wh ic h d o e s n o t e x c ee d t h e r a t e d o u t p u t v o l t a g e . The vol tage
r e q u i r e d f o r t h e l o a d may b e e s t i m a t e d by m u l t i p l y i n g t h e i s o l a t i n g
t r a n s f o r m e r p r im a r y v o l t a g e a t r a t e d l o a d ( w a t t s d i v i d e d b y pr i m a ry
c u r r e n t ) by t h e num ber of t r a n s f o r m e r s c o nn e ct e d i n s e r i e s i n t h e l o a d
c i r c u i t .b) A c o r r e c t o u t p u t c u r r e n t w i t h an o u tp u t v o l t a g e a p p r e c i a b l y l e s s t h a n
t h e e s t im a t e d l oa d v o lt a g e i n d i c a t e s c om pl et e o r p a r t i a l s h o r t i n g o f t h e
l o a d .
c ) A c o r r e c t o u t p u t c u r r e n t w i th a n o u tp u t v o l t a g e e x c e ed i n g t h e r a t e d l o a d
o u t p u t v o l t a g e i n d i c a t e s a n o ve r lo a d.
d ) A r ed uc ed o u t p u t c u r r e n t w i t h a n o u t p u t v o l t a g e i n d i c a t i n g a n o v e r l o a d
i s p o s s i b l y c a u s e d by a p oo r c o nn e ct i on i n t h e l o a d c i r u i t . The
r e g u l a t o r s h o u l d b e d e e n e rg i z e d i m m ed i at e ly t o p r e v e n t d am ag e.
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e ) A r e du c ed o u t p u t c u r r e n t w i t h a n o u t p u t v o l t a g e n o t e x c e e d i n g t h e r a t e d
o u t p u t v o l t a g e i n d i c a t e s a f a u l t y r e g u l a t o r o r r e d uc ed s u p p l y v o lt a g e .
f ) A z e r o ou t p u t c u r r e n t w i t h e x c e s s iv e o u t p u t v o l t a g e i n d i c a t e s a n o pe n i n
t h e l oa d c i r c u i t a nd f a i l u r e o f t h e o p en - ci rc u it p r o t e c t o r i n t h e
r e g u l a t o r . I n t h i s c a s e , t h e r e g u l a t o r m ust be d e e ne r g iz e d i m m ed i a te l yt o p r e v e n t s e r i o u s damage.
g ) CAUTION: The o p e n - c i r c u i t p r o t e c t o r o f t h e r e g u l a t o r must n o t b e
d e a c t i v a t e d o r by -p ass ed d u r i n g t h e s e t e s t s .
3 . 9 . 8 E l e c t r i c a l t e s t s of o th e r equ ipment
3 .9 .8 .1 M ea su re t h e i n p u t a n d o u t p u t v o l t a g e s a nd c u r r e n t s a n d d e t e r m i n e t h e l o a d s
o f t h e c on n ec te d c i r c u i t s . Check t o d et er m in e i f t h e s e v o l t a g e s and l o a d s a r e w i t h i n
t h e m a n u f a c t u r e r ' s r a t i n g o f t h e e q ui p me n t. R ec or d t h e s e m e as ur em e nt s f o r f u t u r e
r e f e r e n c e d u r i n g m ai nt en an ce o r f o r m o d i f ic a t i o n of t h e c i r c u i t .
Tes t s of moni to rs
3.9.9.1 A f t e r t h e t e s t s l i s t e d a b ov e h a ve b e en c o mp l et e d a nd t h e s y s t e m i s f u n c t i o n -
i n g a s d e s i g n e d, m o ni to r s s h o u l d be t e s t e d by s i m u l a t in g s uc h f a i l u r e s a s o p e n - c ir c u i t s ,
s h o r t - c i r c u i t s , g ro un ds , f a i l u r e of l i g h t s , l o s s o f power i n b ot h t h e l i g h t i n g c i r c u i t s
a nd t h e c o n t r o l c i r c u i t s , a nd o b s e r v i n g t h e p e rf o rm a nc e o f t h e m o ni t or . M o n i t o r s w hi ch
f a i l t o p e rf o rm a s i n t e nd e d s h o u ld be r e p a i r e d b e f o r e t h e s y s te m i s a c c e p t e d .
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4.1 GENERAL KEQUIKEMENTS
4 .1 .1 I n i t i a l c o n s i de r a t i o ns
4 .1 .1 .1 I n s t a l l a t i o n of e l e c t r i c a l c a b l e s u nd er gr ou nd i s e x p e n s i v e a n d t e c h n iq u e s t
a s s u r e l o n g an d e f f e c t i v e s e r v i c e w i t h a minimum o f m a i n t e n an c e s h o u l d b e u s ed . A l l
work s h o u l d be d on e by e x p e r i e n c e d p e r s o n n e l r e g u l a r l y e n g ag e d i n t h e i r t y p e o f w ork.
Most underground cables w i l l b e l o c a t e d o n , o r v e ry c l o s e t o , t h e m a no eu vr in g a r e a of
t h e a e ro d ro m e. H ence, a t a c t i v e a er od ro m es g r e a t c a r e must b e e x e r c i s e d t o e n s u r e t h a t
t h e i n s t a l l a t i o n do es no t p r es e nt a h az ar d t o a i r c r a f t o r t o t h e i n s t a l l e r s .
4.1.2 Pre con s t r uc t ion a r rangements
4.1.2.1 O bt ai n p r i o r a p p r o v a l of t h e e n g i n e e r i n c h a r g e f o r t h e m a t e r i a l s , workmen,
t i m e of d a y o r n i g h t f o r t h e w or k, method an d p r oc ed u re s f o r t h e i n s t a l l a t i o n , and
p r o c e d u r e f o r a n y te m p o ra r y o r p e r ma ne nt r e p a i r s t o b e made. A rr an ge f o r c o - o r d i n a t i n gt h e e f f o r t w i th A i r T r a f f i c C o n tr c l i f i t may be invo lved . Ca re fu l l y de te r mine and mar
t h e r o u t e f o r t h e c ab l es . Take a l l r e a so n a bl e p r e ca u t io n s t o p r o t e c t e x i s t i n g
u nd er gr ou nd u t i l i t i e s s u c h a s f u e l t a n ks , w a t er l i n e s , b u r i e d c o n t r o l a nd power c a b l e s ,
e t c . A l l known u t i l i t i e s a nd power a nd c o n t r o l c a b l e s l e a d i n g t o a nd f r o m a n y o p e r a t i n g
f a c i l i t y s h o ul d be m arked i n t h e f i e l d b e f o r e an y work i n t h e g e n e r a l v i c i n i t y i s
s t a r t e d . T h e r e a f t e r a n d t h r o u gh o u t t h e e n t i r e t i m e of c o n s t r u c t i o n t h e y s h o u l d b e
pr o t ec te d f rom any po s s i b l e damage. Any unde rg round c ab le s which a r e damaged dur ing
i n s t a l l a t i o n s h ou l d b e im m ed ia te ly r e p a i r e d w i t h e q u a l q u a l i t y m a t e r i a l .
4 .1 .3 M ethods o f i n s t a l l a t i o n
4 ,1 ,3 .1 T he re a r e two m et ho ds o f i n s t a l l i n g u nd er gr ou nd e l e c t r i c a l c a b l e s , by d i r e c
b u r i a l o r i n d u c t ( c o n d u i t ) . T he se m eth od s a r e d i s c u s s e d be lo w.
4 . 2 UIUCT UUKXAL OF CABLE
4.2.1.1 The major s t e p s of i n s t a l l i n g e l e c t r i c a l c a bl e s by d i r e c t b u r i a l a r e
t r e n c h i n g , p l ac e me n t o f t h e c a b l e , an d b a c k f i l l i n g .
4.2.2 Trenching
4.2.2.1 B a s ic r e q ui r e m en t s . U nl es s r e q u i r e d o t h e r w i s e , a l l c a b l e s i n t h e s a n e
l o c a t i o n a nd r u n n in g i n t h e same g e n e r a l d i r e c t i o n s h o ul d be i n s t a l l e d i n t h e same
t r e n c h . W a ll s of t r e n c h e s s h ou l d b e e s s e n t i a l l y v e r t i c a l s o t h a t a minimum o f s h o u l d e r
s u r f a c e i s d i s t u r b e d . The b o tt o m s u r f a c e o f t r e n c h e s s h o u l d b e e s s e n t i a l l y sm oo th a nd
f r e e f ro m c o a r s e a g g r e g a t e. I f p o s s i b l e , t r e n c h e s s h ou l d be op en ed o n l y t o t h e e x t e n t
t h a t c a b l e s c an be i n s t a l l e d a nd t h e t r e n c h c l o s ed i n t h e same working day. Where t u r f
i s w e l l e s t a b l i s h e d a nd t h e sod can be reanved, i t s h o u l d h e c a r e f u l l y s t r i p p e d and
p r o p e r l y s t o r e d .
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4.2.2.2 The t r e n c h d e p t h s h o u l d b e n o t l e s s t h a n 5 cm b e lo w t h e l e v e lof th e lowes l e s sh ou ld be a minimum of 5 0 cm be low t h e f in i s he d g rade when
on the ae rod rome p ro pe r ty and 7 5 cm be low the f in i s he d g rad e when o f f t h e ae rod rome
p r o pe r ty . I f c a b l e s a r e t o be p l ac ed a t more th a n o ne l e v e l , t h e v e r t i c a l s e p a r a t i o n
s h ou l d be t h e same a s t h e h o r i z o n t a l s e p a r a t i o n i n d i c a t e d i n p a ra g ra p h 4 . 2 . 3 , e x c e p t
v e r t i c a l s e p a r a t i o n of c o n t r o l an d t e l e p h o ne c a b l e s a nd o f low v o l t a g e s p ow er c a b l e sshou ld be no t l e s s than 6 cm. The g round w i r e o r c oun te r po i se shou ld be a minimum o f
1 5 cm a bo ve t h e u pp er m os t l a y e r of c a b l e s . T r en c h d e p t h s s h o u l d a l l o w f o r t h e s e
v e r t i c a l s e p a r a t i on s .
4 .2 .2 .3 Heavy t r a f f i c a r e as . C ab le s s h o u ld n o t be d i r e c t b u r i e d u n d e r pa ve d a r e a s ,
r oad wa ys , r a i l r o a d t r a c k s , o r d i t c h e s . I n t h e s e a r e a s t h e c a b l e s h o ul d b e i n s t a l l e d i n
c o nc re te - en c as e d d u c t s o r i n r i g i d s t e e l c o n d u it .
4 .2 .2 .4 Areas of rock s. Where rock exc ava t io n i s e n c ou n t er e d t h e r o c k s h o u l d b e
removed t o a d ep th of a t l e a s t 8 cm below th e re qu i red ca b l e de p th and i t s h o u l d b e
r e p l a c ed w i t h b e dd in g m a t e r i a l o f e a r t h o r s a n d c o n t a i n i n g n o m i n er a l a g g r e g a t e
p a r t i c l e s l a r g e r t ha n S mm i n d i a m e t e r . When s o l i d r o c k i s e n c o u n t e r e d , a l t e r n a t i v e s
s uch a s r e r o u t i n g t h e t r en c h o r i n s t a l l a t i o n i n r i g i d s t e e l c o nd ui t s h ou ld b econs ide red .
4.2 .2 .5 T re nc h w i d th . T re nc h w i d th f o r a s i n g l e c a b l e s h ou l d b e n o t l e s s t h a n
1 5 cm. Where more th an one ca b l e i s l o c a t e d i n a t r e n c h , t h e t r e n c h w i d t h s h o ul d b e
a d j u s t e d s o t h a t t h e s e p a r a t i o n s g i v e n below c a n be m a i nt a i ne d .
4.2.3 Sepa ra t io n be tween cab l e s
a ) Power c a b l e s , of t h e same c i r c u i t , may be l a i d s i d e by s i d e i n t h e
t r e n c h w i t h o u t s e p a r a t i o n , e x c ep t a s n o t ed b el ow . S e r i e s l i g h t i n g
c a b l e s may b e c o n s i d e r e d a s o f t h e sam e c i r c u i t .
b) Power cables of t h e same o r d i f f e r e n t c i r c u i t s of l e s s t h a n 6 00 v o l t s ,
may be l a i d toge the r i n t h e same t r e n c h w i t h o u t h o r i z o n l s a i s e p a r a t i o n .
c ) Power c a b l e s of d i f f e r e n t c i r c u i t s w i t h v o l t a g e s b et we en 6 00 a n d 5 000
v o l t s sho uld be s ep ar at ed a miniimlim of 10 cm.
d ) A l l power cables , 5 0 00 v o l t s a n d b el ow , s h o u l d be s e p a r a t e d f r o m a l l
c o n t r o l , t e l e p h o ne , a nd c o a x i a l t y p e c a b l e s by a minimum of 1 5 cm .
e ) Power ca bl es , of more tha n 5 000 v o l t s , s h o ul d be s e p a r a t e d f r o m a l l
other cables by a minimum of 3 0 cm.
f ) C o n t r o l , t e l e ph o n e , a nd c o a x i a l c a b l e s may be l a i d i n t h e t r e n c h w i t h o u t
h o r i z o n t a l s e p a r a t i o n f r o m e a c h o t h e r .
g ) V e r t i c a l s e p a r a t i o n s sh o ul d b e s i m i l a r t o t ho s e gi v en i n a ) t h r o u g h f )
e x c e p t t h a t c a b l e s wh ic h do no t r e q u i r e h o r i z o n t a l s e p a r a t i o n s h o ul d be
s e p a r a t e d a minimum o f 6 cm v e r t i c a l l y . No c a b l e s h o u l d d i r e c t l y o v er -
l a p anot her ca bl e because compact ing may damage th e ca bl e .
h ) Ground w i r e s and coun te rpo i se s shou ld be app rox ima te ly 15 cm above the
u pp er mo st l e v e l of t h e c a b l e s .
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4.2.4 I n s t a l l a t i o n of d i r e c t - b u r i a l c a b l e s
4.2.4.1 . B e f o re p l a c i ng a ny c a b l e s , ba c k f i l l a nd c ompac t a 5 cm
l a y e r o f e i t h e r e a r t h o r s an d c o n t ai n i n g n o m a t e r i al a g g r e ga t e p a r t i c l e s l a r g e r t h an
6 mm i n d i am e te r.
4.2.4.2 W he re ve r p o s s i b l e , c a b l e s h o u l d be r u n i n o n e p i e c e ,
w i t h o u t s p l i c e s , f r o m c o n n e c t i o n t o c o n n ec t i on . Use t h e l o n g e s t p r a c t i c a b l e l e n g t h s of
c a b l e i n o r d e r t o mi ni mi ze s p l i c i n g r e q ui r em e n t s. When c a b l e c u t t i n g i s r e q u i r e d , c a b l
e n ds s h o ul d b e e f f e c t i v e l y s e a l e d a g a i n s t m o i s t u r e i m me d ia t el y a f t e r c u t t i n g . Bends of
a r a d i u s l e s s t h a n e i g h t t i me s t h e d i a m e te r f o r r u bb e r- o r p l a s t i c - co v e r e d c a b l e an d
t w e l ve ti m e s t he d i a m e t e r f o r m e t a l l i c -a r m or e d c a b l e s hou l d no t be made. C a b l e t h a t ha s
b ee n k i n k ed s h o u ld n o t b e i n s t a l l e d . A man s h ou l d b e s t a t i o n e d a t t h e r e e l t o o b s er v e
and r e p o r t any i r r e g u l a r i t i e s i n t h e c a b l e when t h e c a b l e i s be i ng un r e e l e d . C a bl e f o r
d i r e c t e a r t h b u r i a l s ho ul d be u n r ee l ed i n p l a c e i n t h e open t r e n c h o r u n r ee l e d n e a r t h e
t r e n c h a nd c a r e f u l l y p la c e d i n t h e t r e n c h bottom. P u l l i n g t h e c a b l e i n t o t h e t r e n ch by
d r a gg i ng ove r t h e g round s hou l d no t be pe r m i t t e d .
4 .2 .4 .3 C a bl e s l a c k l oops . A c a b l e s l a c k l oop of a pp r ox i m a t el y one m e t r e s hou l d be
l e f t o n ea c h e nd o f c a b l e r u n s , a nd a t a l l p o i n t s w he re c a b l e c o n n e c ti o n s a r e b ro ug ht
above ground. The s l a c k l o o p s h o u l d b e i n s t a l l e d a t t h e same minimum d e p t h a s t h e c a b l e
r un . Loops s hou l d ha ve be nds w i t h a n i n ne r r a d i u s no t l e s s t ha n t we l ve t i m e s t he
ou t s i d e d i a m e t e r o f t he c a b l e . Where c a b l e i s b r ou g ht a b o ve g ro un d, a d d i t i o n a l s l a c k
s hou l d be l e f t a bove gr ound. A t a l l c a bl e s p l i c e s , p ro v id e s l a c k l o o ps f r e e of bends a
t h e s p l i c e o r w it h i n 3 0 cm o f t he e nds o f t he s p l i c e .
4.2.4.4 F i n a l b a c k f i l l i n g . A f t e r t h e c a b l e h a s b ee n i n s t a l l e d , t h e t r e n c h s ho ul d b e
b a c k f i l l e d a s f ol l o ws :
a ) B a c k f i l l s e p a r a t i n g c a b l e s s h o u ld be f i r m l y tamped i n p l ac e . The cable
s e p a r a t i o n s g i ve n i n 4.2.3 . should be mainta ined. T he se s e pa r a t i o ns may
be e i t h e r h o r i z o n t a l , v e r t i c a l , o r a c om bi na ti on of t h e two.
b ) The f i r s t l a y e r of b a c k f i l l i n g sh o u l d b e n o t l e s s th a n 7 .5 cm deep,
l o o s e m ea su re me nt , a nd s h o u l d b e e i t h e r e a r t h o r s a nd c o n t a i n i n g no
m a t e r i a l a gg r e ga t e p a r t i c l e s l a r g e r t h a n 6 mm d i a m e t e r . T h i s l a y e r
s hou l d no t be c om pa ct ed , e xc e p t f o r t a mp ing t o m a i n t a i n s e pa r a t i on of
c a b l e s .
c ) The second la ye r should be no t l e s s than 12 cm deep , lo os e measurement ,
a nd s h o ul d c o n t a i n no p a r t i c l e s l a r g e r t h a n 2 5 mm d i a m e t e r .
d ) The r em a i nde r of t h e ba c k f i l l i n g may be e xc a va t e d o r i m por t e d m a t e r i a l
a nd s h o u l d n o t c o n t a i n s t o n e s o r a g g r e ga t e l a r g e r t h a n 1 0 0 mm i n
d i a m et e r . The t h i r d a nd s u b se q u en t l a y e r s o f t h e b a c k f i l l i n g s h o u ld n o t
exceed 2 0 cm i n maximum de pt h, lo o se measurement. The sec ond and
s ubs e que n t l a y e r s s hou l d be t ho r ough ly t am pe d a nd com pa ct ed t o a t l e a s t
t h e d e n s i t y o f t h e a d j a c e n t u n d i st u rb e d s o i l . I f n e c e s s ar y t o o b t a i n
t h e de s i r e d c ompa ct i on , t he b a c k f i l l m a t e r i a l may be m o i s t e ne d o r
a e r a t e d a s r e q u i r e d . T re n ch e s s h o u l d n o t b e e x c e s s i v e l y w e t an d s h o u ld
n o t c o n t a i n p o o l s o f wa t e r d u r i n g t h e b a c k f i l l i n g o p e r a t i o n s . The
t r e n c h s h o u l d be c o m p l e t el y b a c k f i l l e d a nd t amped l e v e l w i t h t h e
a d j a c e n t s u r f a c e .
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e ) When sod i s t o be p l ac e d ov e r t h e t r e n c h , t h e b a c k f i l l i n g s h o u l d be
s t o p pe d a t a d e p t h e q u a l t o t h e t h i c k n e s s of t h e so d t o b e u s ed . Any
e x c e s s e x c a v a t e d m a t e r i a l s h o u l d b e r em ov ed .
Where sod has been removed i t s h o u ld b e r e p l ac e d a s s oo n a s p o s s i b l e
a f t e r t he b a c k f i l l i n g i s comple ted . A l l a r e a s d i s t u r b e d by t h et r e n c h i ng , s t o r i n g of d i r t , c a b l e l a y i n g , pad c o n s t r u c t i o n , a nd o t h e r
work sh o ul d be r e s t o r e d t o i t s o r i g i n a l c o n d i t i on . The r e s t o r a t i o n
s h ou l d i n c l u d e a ny n e c es s a ry t o p s o i l i n g , f e r t i l i z i n g , l i m i n g , s e e d i n g ,
s o d d in g , s p r i g g i n g , o r n ru lc hi ng . I f t r e n c h i n g c u t s a r e made t h r o u g h
paved a r e a s , t h e c u t s , a f t e r p r o pe r b a c k f i l l i n g , s h ou l d b e r e s u r f a c e d
w i t h p av in g s i m i l a r t o t h e o r i g i n a l pa vi ng . R e su r fa ce d c u t s s h ou l d be
l e v e l w i t h t h e o r i g i n a l pa v in g , f r e e f r om c r a c k s , an d c a p ab l e o f
w i t hs t a nd i n g t r a f f i c l o a d s impos ed w i t ho u t s e t t l i n g o r c r a c k i n g.
4.3 INSTALLATION OF DUCTS (CONDUIT)
I n s t a l l a t i o n t e c h n i q u e s a n d p r o c e d u r e s
4 . 3 .1 , l S e l e c t i o n o f r o u t e s . D u c t- l i ne r o u t e s s h o u l d b e s e l e c t e d t o b a l a n c e maxirnum
f l e x i b i l i t y w i t h minimum c o s t a n d t o a v oi d f o u n da t i on s f o r f u t u r e b u i l d i n g s a nd o t h e r
s t r u c t u r e s . W h e r e i t may b e n e c e s s a r y t o r u n c om mu ni ca ti on l i n e s a l o n g w i t h e l e c t r i c
pow er d i s t r i b u t i o n l i n e s , two i s o l a t e d s ys t e m s i n s e p a r a t e rnan hole c o mp a rt m en t s s h o u l d
b e pr o vi d ed . Where p o s s i b l e , d u c t s s h o u ld be i n s t a l l e d i n t h e s ame c o n c r e t e e nv e l op e .
E l e c t r i c and c om mu nic at io n d u c t s s h o u l d be k e p t c l e a r o f a l l o t h e r u n d er g ro u nd
u t i l i t i e s , e s p e c i a l l y h ig h -t e mp e ra tu r e w a t er o r s t ea m p i p es .
4 . 3 . 1 , 2 Duct m a t e r i a l s . A cc ep ta bl e s t a n d a r d m a t e r i a l s f o r d u c t s i n c l u d e f i b e r ,
a sb es to s- ce me nt , t i l e , and p l a s t i c . K g i d s t e e l c o n du i t may a l s o be i n s t a l l e d belowg r a d e a nd s h o u ld b e pr o vi d ed w i t h f i e l d o r f a c t o r y a p p l i e d c o a t i n g s wh er e r e q u i r e d .
4 .3 .1 .3 S iz e o f duc t s . S ize o f con du i t s i n a duc t bank shou ld be no t l e s s t h a n
10 cm i n s i d e d i a m e t e r e x c e p t t h a t d u c t s f o r c o m m n i c a t i o n l i n e s w i t h a minimum d i a m e t e r
of 7.5 cm a r e accep tab le .
4.3.1.4 I n s t a l l a t i o n of d u c t s w i th o u t c o n c r e t e en ca se me nt . T r en ch es f o r s i n g l e - d u c t
l i n e s shou ld be no t l e s s th an 15 cm nor more than 30 cm wide , and th e t r e nc h f o r two o r
more d u c t s i n s t a l l e d a t t h e same l e v e l s h o u l d b e p r o p o r t i o n a t e l y w i d er . T re nc h b ot to ms
f o r d u c t s w i t h o u t c o n c r e t e e nc as em en t s h o l d b e made t o c on fo .rm a c c u r a t e l y t o g r a d e s o a s
t o p r o v i d e u n if o rm s u p p o r t f o r t h e d u c t a l o n g i t s e n t i r e l e ng th . A l a y e r of f i n e e a r t h
m a t e r i a l a t l e a s t 1 0 cm t h i c k ( l o o s e m ea su re me nt ) s h o u l d be p l a c e d i n t h e b o t t o m o f t h e
t r e n c h a s b ed di ng f o r t h e d u c t . The be dd in g m a t e r i a l s h ou l d c o n s i s t of s o f t d i r t , s a nd ,
o r o t h er f i n e f i l l , and i t s h ou l d c o n t a i n n o p a r t i c l e s l a r g e r t h a n 6 mn d iame te r . The
bedd ing ma te r i a l shou ld be tamped u n t i l f i rm . When two or rnore d u c t s a r e i n s t a l l e d i n
t h e same t r e n c h w t t ho u t c o n c r e t e e n ca s em e nt , t h e y s h o u l d be s p a c e d n o t l e s s t h a n 5 cm
a p a r t ( m ea s ur e d f r om o u t s i d e w a l l t o o u t s i d e w a l l ) i n a h o r iz o n t a l d i r e c t i o n o r o o t l e s s
t h a n 1 5 cm a p a r t i n a v e r t i c a l d i r e c t i o n . R i g i d s t e e l ancl h e a v y - w a l l c o n d u i t may b e
d i r e c t e a r t h b ur i ed . A l l o t h e r c o n d u i t s s h o u l d b e e n c as e d .
4 .3 .1 .5 Lns ta l l a t ion of d u c t s e n c as e d i n c o n c r e t e . Al.]. d u ct s i n s t a l l e d i n c o n cr e t e
encasement s h u u l d be p l a ced on a L ay er of concre te n o t l e s s t h a n 9 - 5 c m thick. Where
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( me as ur ed f r o m o u t s i d e w a l l t o o u t s i d e w a l l ) . A s t h e d u c t l a y i n g p ro g r e s s e s , c o n c r e t e
n o t l e s s t h an 7 .5 cm t h i c k s hou l d be p l a c e d a r ound t h e s i de s and t op o f t h e duc t ba nk .
F la red ends of d u c t s o r c o u p l i n g s sh o u l d b e i n s t a l l e d f l u s h w i t h t h e c o n c r e t e e nc as em en t
o r i n s i d e w a l l s of m anho le s o r handho l es . I n t e r l oc k s pa c e r s s hou l d be u s e d a t not more
t ha n 1.5 m e t re s p a c i n g t o i n s u r e u n i f o r m sp a c i n g b et we en d u c t s . J o i n t s i n a d j ac e nt
du ct s shou ld be s t agg ere d a minimum of 6 0 cm a pa r t and should be made wate rpro of p r i o rt o c o n c re t i ng . No d u c t h a vi n g a d e f e c t i v e j o i n t s h ou l d b e i n s t a l l e d . Concrete-encased
d u c t o r r i g i d s t e e l c o n d ui t s h ou ld be i n s t a l l e d s o t h a t t h e t o p o f t h e c o n c r e t e en ve lo pe
o r c o n d u it i s n o t l e s s t h an 4 0 cm below t he bot tom of th e pavin g where i t i s i n s t a l l e d
under roadways, r a i l ro ad s , r unways, t ax iways , o t he r paved a r ea s , and d i t ch es and no t
l e s s t h an 4 0 cm below t he f i n i sh ed g rade e l sewhere .
4 .3 .1 .6 Grounding bushings. Mhere r i g i d s t e e l c on d u i t e n t e r s o r l e a v e s a manhole o r
ha ndho le a g r ound ing bus h i ng s hou l d be p rov i ded f o r a l l c ondu i t s .
4.3.1.7 Arrangement of d uc t banks. An ar r angement of two duc ts wide or h i gh shou ld
b e u se d f o r b e s t h e a t d i s s i p a t i o n . C o rr e sp o n di n gl y , t h e d u c t ba nk s may b e s e v e r a l d u c t s
h i gh o r w i de . (This may be impo ss ib l e where a l a rg e number of du c ts a r e invol ved . ) The
v e r t i c a l two c ondui t- wi de a r ra nge m en t e na b l e s t h e c a b l e s t o be more e a s i l y r a c ke d onm anho le w a l l s bu t may no t be a s e c onom ic a l a s t he h o r i z on t a l two c ondu i t - h i gh
ar r angement . For d imensions and a r r angement of duc t banks, s e e F igu re 4-1 .
4 .3 .1 .8 Drainage. A l l d u c t l i n e s s h o u l d be l a i d s o a s t o s l o p e t ow ar d h an d h ol e s,
m anho le s a nd duc t e nds f o r d r a i na ge . G ra de s s hou l d be a t l e a s t 2.5 m i l l i m e t r e s p e r
metre. Where i t i s n o t p r a c t i c a b l e t o m ai n ta i n t h e s l o p e a l l o ne way, t h e d u c t l i n e s
may be s l ope d f rom t h e c e n t e r i n bo t h d i r e c t i o ns t ow ar d m anho le s, ha ndho l e s , o r duc t
ends . Pocke ts o r t r a ps where mois ture may accum ~i la te hould be avoided .
4 .3 .1 .9 P u l l w i r e. Each s pa r e duc t i n s t a l l e d s hou l d be p rov i ded w i t h a c oppe r - c la d
s t e e l p u l l w i r e of n o t l e s s t h a n 5 mm2 i n a r e a * The ope n e nds of t h e s p a r e duc t s s hou l d
be plugged wi t h r emovable tape red p lugs . The p lu g s h o u l d s e c u r e t h e p u l l w i r e f i r m l y .
4 .3 .1 .10 S u f f i c i e n t du c t s f o r p la nn ed i n s t a l l a t i o n s , f u t u r e
e xpa ns i on , p l u s a minimum of 2 5 p e r c e n t o f s p a r e d u c t s , s h ou l d be i n c l u d e d f o r a l l new
underground sys tems.
4.4 MANHOLES AND HANDHOLES
4 .4 .1 S e l e c t i o n
4 .4 .1 .1 Fac t or s be a r i ng on th e choic e of manholes and handholes a r e number ,
d i r e c t i o n , a nd l oc a t i on o f duc t r uns ; c a b l e r a c k a r r ange m e nt s ; m ethod o f d r a i na ge ;
adequacy of work space ( es pe c i a l ly i f equipment i s t o b e i n s t a l l e d i n t h e m an ho le ); a nd
t h e s i z e of t h e o p e n i ng r e q u i r e d t o i n s t a l l an d remove e q ui pm en t.
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SI NG L E DUCT
ELECTR IC OR COMMUNICATION CO M BI NED EL ECTRI C (E) A N D
CO M M UNlCAT lO N ( C)
1.5 cm TYPICAL
1.25 cm BARS AT 15 cm
TO 20 cm ON CENTRES$
7.5 cm TYPICA L(2.5 cm WIRE HOOP)
APPROXIMATELY 20 cm
ON C E N T R E S ~
REI NFO RCED DUCT BANKS
1. W HERE REI NFO RCEM ENT I S PRO VI DED UNDER RAI L R O AD TRA CKS I T SHO UL DE X T E N D A T L E A S T 3.5 m BEYO ND TH E O UTER RAI L S .
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4.4.2 Location
4 .4 .2 ,1 M an ho le s o r h a n d h o le s s h o u l d b e p l a c e d w h er e r e q u i r e d f o r c o n n e c t i o n s o r
s p l i c e s a nd where c o n f l i c t w i t h o t h e r u t i l i t i e s w i l l be avo ided* Manho le se pa ra t i on
s h o u l d n o t e x c e ed 2 00 m e t r e s o n s t r a i g h t r u n s a nd 1 0 0 metres on cu rved duc t runs .
Spac ing shou ld be dec r ea sed whe re nece ssa ry t o p r ev e nt i n s t a l l a t i o n d amage d u r i n gp u l l i n g of c a b l e s . S t r a i n s ho ul d be l im i. ted d u ri n g i n s t a l l a t i o n t o a p o i n t t h a t w i l l
n o t damage c a b l e i n s u l a t i o n o r d ef or m t h e c a b l e ( s e e T a b l e 4-1).
4.4.3 Stubs
4.4.3.1 It i s good p r a c t i c e t o p r o v id e a s e t o f t wo o r mor e s p a r e s t u b s ( s h o r t
l e n g t h s o f d u c t s l e a d i n g o u t f r om t h e m an ho le ) s o t h a t t h e manh ole w a l l n e ed n o t b e
d i s t u r b e d when a f u t u r e e x t e n s i o n i s made. The s t ub s shou ld be p lugged on bo th ends .
4.4.4 Hardware
4.4.4.1 Hardware a p p l i c a b l e t o t h e i n s t a l l a t i o n s h o u l d be c ho se n. W here f l a r e d e n d
o f d u c t s a r e p r o vi d ed , c ab le - du ct s h i e l d s a r e n e c e s sa r y o n ly f o r p r o t e c t i o n of m e t a l l i c -s h e a t h e d c a b l e s .
Two-section manholes
4 .4 .5 .1 T w o s e c t i o n m an ho le s s h o ul d b e u s e d t o m a i n t a i n s e p a r a t i o n of t h e c i r c u i t s
w h er e e l e c t r i c power a n d co mm un ic at io n l i n e s a r e i n s t a l l e d i n t h e same d u c t b ank o r u s e
the same manhole.
4.5 INSTALLATION OF UNDERGROUND CABLES
4.5.1 P r e ~ a r a t i o n f d u c t s
4.5.1.1 A f t e r t h e d u c t i n s t a l l a t i o n i s c om pl et ed , t h e c a b l e s a r e i n s t a l l e d b y
d r a wi n g o r p u l l i n g i n t o t h e d u c ~ s . The d u c t s h o u ld b e op en , c o n t i nu o u s , a nd c l e a r of
d e b r i s b e f o r e t h e c a b l e i s i n s t a l l e d . The c a b l e s h o ul d be i n s t a l l e d i n a manner t o
p r e v e nt h ar m fu l s t r e t c h i n g o f t h e c o nd uc to r, i n j u r y t o t h e i n s u l a t i o n , o r damage t o t h e
o u t e r p r o t e c t i v e c o v e r in g . The e n ds of a l l c a b l e s s ho u l d b e s e a l e d w i t h m o i s t u r e s e a l
t a p e b e f o r e i n s t a l l i n g , and t h e y s h o ul d b e k e pt s e a l e d u n t i l c o nn e ct i on s a re made.
Where more t h a n on e c a b l e i s t o be i n s t a l l e d i n a d u c t o r c o n d u i t , a l l c a b l e s h o ul d be
i n s t a l l e d a t t he same t i m e . In no c a s e s h o u ld a s p l i c e o r c o n n e c t io n be p l a c e d i n a
d u c t o r c o n d ui t .
4.5 .2 C a bl e p u l l i n g i n d u c t s
4.5.2.1 . The c a b l e t o be i n s t a l l e d i n t h e d u c t may b e p u l l e d by a
power winch o r by hand. An ade qua te amount of ca bl e p u l l in g compound sho ul d be used on
a l l p u l l s . P e t ro l eu m g r e a s e s h o u l d n o t b e u s e d. The s u r f a c e o f a n y c a b l e s h e a t h o r
j a c k e t s h o u l d n o t be damaged t o a d e p t h g r e a t e r t h a n 1110th i t s o r i g i n a l t h i c kn e s s . Th
c a b l e s h o u l d n o t b e f l a t t e n e d o u t o f r ou nd more t h a n 1 1 10 t h i t s o u t s i d e d i a m e t e r.
M ax im m p u l l i n g t e n s i a n s f o r commonly i n s t a l l - e d c a b l e s a r e l i s t e d i n T a b l e 4-1. The
l i m i t a t i o n s i n T ab le 4-1 a r e n o t i n t en d ed t o p re c lu d e t h e u s e of s t e e l o r w i r e r op e a s a
means of pu l l in g . However , ur i les s a dynamometer i s u se d t o i n d i c a t e t h e g r o p er t e n s i o n
f ~ sh e cab l e be i ng p u l l e d , a ha r nes s of Che p rope r sLze rope t h a t will l i m i t t h e
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Table 4-1
MAXIMUM ALLOWABLE NON-ARMOKED CABLE PULL USING DYNAMOMETER OR ROPE
CABLE TENSION ROPE DIAMETER
2 - l c 8 . 4 mm2 Sol 125 kg 4.8 mm C
3 - l c 8 . 4 mm2 S o l 1 6 5 kg 6.4 mm C 4.8 mm M
4 - l c 8.4 mm2 So l 250 kg 6.4 mm M
2 - 1 c 1 3 , 3 mm2 S t s 1 9 0 kg 6.4 mm C 4.8 mm M
3 - l c 1 3. 3 mm2 S t r 2 8 5 kg 8.0 mm C 6.4 mm M
4 - l c 13.3 mm2 S t r 3 8 0 kg 9.6 mm c 4.8 mm D
1 - 2c 8.4 mm2 S t r 140 kg 6.4 mm C
1 - 3c 8.4 mm2 S t r 180 kg 6.4 mm C
1 - 4c 8.4 mm2 S t r 26 5 kg 6.4 mm M
p--l - 2c 13.3 mm2 S t r 2 2 0 kg 6.4 mm C 4.8 mm M
1 - 3c 13.3 mm2 S t r 31 0 kg 8.0 mm C
1 - 4c 13.3 mm2 S t r 4 0 0 kg 9.6 mm C 8.0 mm M 4.8 mm D-1 - 6c 3.3 mm2 S t r 1 4 0 kg 6.4 mm C
1 - 12 c 3.3 mm2 ~ t r 285 kg 8. 0 mm C 6.4 mm M
KG - 213/U 55 kg 4.8 m C (formerly KG-8/U)
KG - 214/U 65 kg 4.8 mm C: ( f o r m e r l y KG--9/U)-p--- PKG - 216/U 60 kg 4.8 mm C (formerly RG-13/U)
RG - 217/U 115 kg 6.4 mm M (formerly RG-14/U)
RG - 2 1 8 / U 36 0 kg 11.5 mm C (formerly RG-17/U)
c - Conductor So l - S o l i d S t r - Stranded PK - P a i r
C - C o t t o n M - M a n i l a D - Dacron N - Nylon
Maximum p u l l i n g t e n s i o n s f o r c a b l e s n o t l i s t e d s h o u l d b e o b t a i n e d f ro m t h e m a n u f a c t u r er
o f t h e c a b l e .
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t e n s i o n of t h e p u l l t o f o r c e s i n d i c a t e d i n T ab le 4-1 s h o u l d b e u s e d . Any com bi nat ion of
a g r ou p of c a b l e s t o be p u l l e d i n t o a d u c t s h o u l d n o t e x c ee d t h e sum o f i n d i v i d u a l
a l l o w a b l e t e n s i o n o f e a c h c a b l e p l u s 1 5 p e r c e n t .
4.5.2.2 L en gt h o f p u l l . To m in im iz e s p l i c i n g , t h e l o n g e s t p r a c t i c a b l e l e n g t h s o f
c a b l e s h o u l d b e p u l l e d i n t o t h e d u c t s a t on e t im e . U n le ss o t h e r w i s e r e q u i r e d , m an ho le sand handho le s s ho ul d be a s f a r a p a r t a s p r a c t i c a b l e f o r t h e t y p e of c a b l e b e in g
i n s t a l l e d , b u t u n d er n o c o n d i t i o n s h o u l d t h e d i s t a n c e b e tw ee n h a n d ho l e s o r m a nh ol es
exceed 200 metres .
4 .5 .2 .3 S e v e ra l ca b l e s i n s t a l l e d i n one d u c t. The f o l lo w i n g a r e a p p l i c a b l e t o t h e
i n s t a l l a t i o n of two o r more c a b l e s i n t h e same d u c t.
a ) Power c a b l e s o f t h e sam e v o l t a g e may be i n s t a l l e d i n t h e s am e d u c t .
b ) Power c a b l e s o f l e s s t h a n 600 v o l t s may be i n s t a l l e d i n t h e sam e d u c t .
c ) Power c a b l e s of l e s s t h a n 600 v o l t s s h o u l d n o t b e i n s t a l l e d i n t h e sam e
d u c t w i t h c o n t r o l , t e le p ho n e, o r c o a x i a l t y p e c a b l es .
d ) Power c a b l e s of more t h a n 60 0 v o l t s s h o u l d n o t b e i n s t a l l e d i n t h e sa me
d u c t w i t h c o n t r o l . t e l e p h o n e , c o a x i a l o r p ower c a b l e s o f l e s s than 600
v o l t s .
e ) C o n t r o l , t e l e p h o n e , a nd c o a x i a l c a b l e s may b e i n s t a l l e d i n t h e sam e
d u c t .
f ) Power, c o n t r o l , a n d te l e ph o n e c a b l e s may b e i n s t a l l e d i n t h e s ame d u c t
s y st e m , s u b j e c t t o p r o v i s i o n s o f s u b- p ar a gr a ph s g ) an d h ) .
g ) C ab le i n s t a l l a t i o n i n m an ho le s o r h a n d ho l e s. Power an d c o n t r o l c a b l e s
s h o ul d be i n s t a l l e d i n s e p a r a t e m an ho le s a nd h an d h o le s u n l e s s r e q u i r e do t h e r w i s e . I f s p a c e i s a v a i l a b le , c a b le s l a c k s u f f i c i e n t f o r one s p l i c e
f o r e a c h c a b l e s h o u ld b e l e f t i n e a c h m an ho le .
h ) Sep a ra t i on o f cab l e s i n manholes and handho ie s . When i t i s n o t p o s s i b i e
t o i n s t a l l power a nd o t h e r t y p e c a b l e s i n s e p a r a t e m a nh ol es o r hand-
h o l e s , t h e y sh o ul d be i n s t a l l e d i n s e p a r a t e c om pa rt men ts o r o n o p p o s i t e
s i d es o f th e manho le o r handhole .
I n s t a l l a t i o n o f c a b l e s i n m an ho le s an d h a n d ho l e s
4 .5 .3 .1 C ab le r a c k s . C ab le s s h a l l be c a r e f u l l y f or me d a r ou n d t h e i n t e r i o r of man-
h o l e s o r h a nd h ol e s a v o i d i n g s h a r p b en ds o r k i n k s. A l l s p l i c e s an d c a b l e s s h o u l d be t i e d
t o c a b l e r a c k s u s in g 3. 2 mm d iame te r ny lon l i n e . Handhole and manho le rac ks shou ld be
t h e p l a s t i c t y p e o r p ro vi de d w i t h p o r c e l a i n i n s u l a t o r s . S p l i c e s o r c o n n e ct o r s s h ou l d be
a minimum of 0 .6 metre f rom the mouth of th e du ct openin g i n t o th e manhole o r handhole .
Where f e a s i b l e , s p l i c e s i n d i f f e r e n t c a b l e s s ho u ld be s t a g g er e d .
4 S . 3 . 2 C ab le t e r m i n a t i o n s . T e rm i n at i on o f a l l c o n t r o l , t e l e p h o n e , a n d c o a x i a l
c a b l e s s h o u l d b e a s r e q u i r e d . T e r m i na t i on o f a l l power c a b l e s r a t e d a b ov e 5 0 0 0 v o l t s
should be made with a s t r e s s r e l i e f d e v i c e . Where p o th e ad s a r e u s e d, s t r i c t conformance
t o man ufac tu re r ' s r ecommenda tions shou ld be fo l lowed . Where t e rm ina t io ns a r e made a t
t r a n s f o r m e r b u s h i n g s , e xp os ed c o a d u c t i n g s u r f a c e s on b o t h h i g h - a nd l o w - v o l r a g e s i d e s
s h o u l d be t a p e d f o r f u l l v o l t a g e a nd p a i n t e d w i t h a h i g h i n s u l a t i o n w a t e r - r e si s t a n t
co a t i n g e
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4.5.3.3 The f o l l o w i n g c o n d i t i o n s a p p l y t o t h e g r ou n d in g o f
c a b l e s .
a ) A l l s h i e l d e d power c a b l e s s h o u l d h a v e t h e s h i e l d g ro un de d a t e a c h e n d .
The grounding condu ctor sho uld be connected t o a ground rod by means of
a g r ou n di ng c o n ne c to r s p e c i f i c a l l y d e s ig n ed f o r t h i s p ur p os e. Thes h i e l d s o r a rmor on d i r e c t ea r th -bur i ed power ca b l e s shou ld be grounded
o n e ac h e nd , b u t n o t a t t h e s p l i c e s .
b ) A l l s h i e l d e d c o n t r o l c a b l e s s h o u ld ha v e t h e s h i e l d g r ou nd ed a t each end .
The s h i e l d a t e a c h s p l i c e s ho u l d h av e i n s u l a t i o n r e s i s t a n c e f ro m gr ou nd
e q u a l t o t h a t of t h e o r i g i n a l c a b le .
c ) T el ep ho ne c a b l e s s h o u l d h av e t h e s h i e l d s g r ou n de d a t-ne end only . The
s h i e l d a t e a ch s p l i c e s ho u l d ha ve i n s u l a t i o n r e s i s t a n c e f r om gr ou nd
e q ua l t o t h a t o f t h e o r i g i n a l c a bl e .
d ) C o a xi a l c a b l e s h i e l d s s ho u l d b e i n s u l a t e d fr o m g ro un d t h ro u g h o u t t h e
l e n g t h o f t h e c a b l e ru n . The s h i e l d s sh o u ld be g ro un de d o n l y a t t h ec o a x i a l c o n n e c to r t e r m i n a t i n g i n t o t h e e q ui pm en t on each end o f th e
c a b l e r u n ,
4.5.4 P r e s su r i z e d t y p e c o a x i a l c a b l e s
4.5.4.1 P r e c a u ti o n s . S p e c i a l p r e c a u t i o n s s h o u l d b e o b s er v e d d u r i n g t h e i n s t a l l a t i o n
o f g a s - f i l l e d c o a x i a l c a b l e s . T he se c a b l e s s h o u l d b e f u r n i s h e d a nd i n s t a l l e d i n one
p i e c e u nd e r n i t r o g e n g a s p r e s s u r e w i t h c a b l e an d s e a l s k e p t s e c u r e l y i n p l a c e a t a l l
t i m e s d u r i n g c a b l e h a n dl i n g, s h i p p i ng , an d i n s t a l l a t i o n . Do n ot c u t o r s p l i c e t h i s
c a b l e a t a n y t im e . A s t h e c a b l e i s unwound f rom th e re e l , a supp lementa ry de v i ce fo r
s t r a i g h t e n i n g t h i s c a b l e i s d e s i r a b l e , U tm os t c a r e s h o u l d b e e x e r c i s e d a t a l l t i m e s t o
p r e v e n t k j n k i ng an y p a r t o f t h e c a b l e du r i ng i n s t a l l a t i o n .
4.5.4.2 P r e - i n s t a l l a t i o n c h ec k, I n o r d e r t o d e t er m i ne w he th er t h e c a b l e h a s be e n
damaged o r p u n c t u r e d, d e t e r m i n e i f t h e n i t r o g e n g a s s h i p p i n g p r e s s u r e i s s t i l l r e t a i n e d
i n t h e c a b l e . I f t h i s g a s p r e s s u r e r e a d i n g h a s d e c re a se d a nd t h e l o s s i s n o t d ue t o
t e m p e r a t u r e c h an g e, a n i t r o g e n g a s t e s t s h o u i d b e c on d uc t ed .
4.5.4.3 . S t y r o f l e x c o a x i a l c a b l e o f 4 5 mm d i a m e t e r
s h o ul d n o t b e s u b j e c t e d t o a b en di ng r a d i u s o f l e s s t h a n o ne m e t re d u r i n g i n s t a l l a t i o n
o r l e s s t h an 0.6 metre ra d i us when s ecured i n p lace . The maximum a l low ab le p u l l i ng
t e ns i on f o r t h i s s i z e of c a bl e i s 800 kg. H e l i a x c o a x i a l c a b l e s h o u l d n o t b e s u b j e c t e d
t o a b e nd i ng r a d i u s of l e s s t h a n 0.75 m et re d u r in g i n s t a l l a t i o n no r l e s s t h a n a 0.5
m e t r e r a d i u s when se c u r e d i n p l a c e . The maximum a l l o w a b l e p u l l i n g t e n s i o n f o r t h i s s i z e
of cab le i s 380 kg.
4.5.4.4 S l a ck c o i l c a b l e l o o p s s h ou l d n o t b e us ed f o r p r e s s u r i z e d c o a x i a l c a b l e s .
T he c a b l e e n d s ho u l d be f e d t h r o u gh t h e o p e ni n g p r o vi d ed a t t h e b u i l d i n g f r o m t h e r e e l
l o c a t e d o u t s i d e t h e b u i l d i n g . The c a b l e b et we en t h e s t r u c t u r e e n t r a n c e a nd t h e
r e s p e c t i v e c a b l e end s h o ul d c on t in u e i n t o t h e b u i l d i n g o n r e l a t i v e l y t h e s a m e h o r i z o n t a l
p lane . Bends shou ld no t be l e s s than th e minimum pre sc r i bed above . Tempora r i ly suppo r t
t h e c a b l e en d s o t h a t t h e c a b l e w i l l n o t " dr oo p" o r " h an g" , p e n di n g f i n a l c o n n e c t i o n t o
t h e e l e c t r o n i c a p pa r at u s.
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C ab le i n s t a l l a t i o n i n saw c u t s
4 .5 .5 .1 Use o f saw c u t s . When new l i g h t s a r e i n s t a l l e d i n e x i s t i n g p a v em e n t s, f o r
example, runway c e n t r e l i n e a nd t ouchdow n zo ne l i g h t s a nd t a x iw a y c e n t r e l i n e l i g h t s ,
c a b l e i n s t a l l a t i o n i n saw c u t s o r k e r f s may be r e q u i r e d . Only s ec o n d ar y c i r c u i t s o f
i s o l a t i n g t r a n s f o r m e r s s h ou l d b e i n s t a l l e d i n saw c ut s . T h i s t e c h n i q u e s h o u l d = b eused i n new pavement a s i t weakens t h e pavement.
4 .5.5 .2 Cu t t i ng th e pavement . Saw cu ts a r e made wi th d iamond b l ad e s a w s . The saw
c u t o r k e r f s h ou l d be n o t l e s s t h a n 1 cm wide and not l e s s t han 2 cm dee p. The wi dt h
and d e p t h sh o ul d be i n c r e as e d i f s e v e r a l c a b l e s a r e t o b e i n s t a l l e d i n t h e s ame saw c u t
a nd a t e n t r a n c es t o l i g h t f i x t u r e s , t r a ns f o rm e r e n c l os u r e s , a nd s p l i c e ch am be rs . The
d e p t h o f t h e k e r f s h o u l d b e i n c r e a s e d s u f f i c i e n t l y t o a l l o w s l a c k w i r e u n d e r t h e p av e-
m en t j o i n t w here a s aw c u t c r o s s e s a c o n s t r u c t i o n j o i n t i n t h e p av em en t. A l l saw cu t s
s ho ul d be i n s t r a i g h t l i n e s w it h v e r t i c a l s i d e s . The i n t e r s e c t i n g e dg es s h o ul d be
c ha mf er ed w he re saw c u t s i n t e r s e c t t o r e d u c e damage t o t h e c a b l e i n s u l a t i o n . It may be
d e s i r a b l e t o c o l l e c t t h e d e b r i s f r om saw c u t t i n g an d p r o ce s s i t t o r e c o v e r t h e d iam ond
g r i t .
4.5.5.3 C l e a ni n g t h e s aw c u t . The s aw c u t s h o u l d be s a n d b l a s t e d t o r em ov e a l l
f o r e i g n a nd l o o s e m a t e r i a l . Sand f o r b l a s t i n g s h o u ld b e of t h e p r o pe r s i z e an d q u a l i t y
f o r t h i s work a nd a p p l i e d w i t h pr o p er s i z e n o z z l e s an d a i r p r e s s u r e . I m m ed i at el y p r i o r
t o i n s t a l l i n g t h e c a bl e s o r w i r e s , t h e s aw c u t s ho u ld be f l u s h e d w i t h a hi gh -s pe ed j e t
o f w a t er o r s t ea m a nd d r i e d w i t h a h i g h s p e e d j e t o f a i r . Keep t h i s a r e a c l e a n u n t i l
comple t ion o f th e work .
4.5.5.4 I n s t a L l a t i o n of c a b l e s i n saw c u t s . S i nc e t h e s e c a b l e s a r e f o r t h e
s ec on da ry c u r r e n t of i s o l a t i n g tr a n s f o r m e r s, 6 0 0 - vo l t i n s u l a t i o n s u i t a b l e f o r w et o r
damp l o c a t i o n s s h o u l d b e u s e d . P o l y v i n y l - c h l o r i d e , p o l y e t h y l e n e , r u b b e r , a n d e t h y l e n e -
p ro by le ne -r ub be r a r e s u i t a b l e t y p e s o f i n s u l a t i o n . A j a c k e t o ve r t h e i n s u l a t i o n i s n o t
r e q u i r e d . The c o n d u c t o r s h o u l d b e s t r a n d e d c o p p e r n o t l e s s t h a n 3.3 mm2 i n c ro ss -
s e c t i o n a l a r e a . I f t h e t o t a l l e n g t h of t h e c on du ct or w i l l exceed 350 me t re s , t h e
c ot ld uc to r s i z e s h o ul d be n o t l e s s t h a n 5 .2 mm2. U s u a i l y s i n g l e - c o n du c t o r w i r e i s u s e d ,
but two-conductor c ab le i s a c c e p t a b l e . Do n o t s p l i c e t h e c a b l e i n t h e s a w c u t s ; u se
o n l y f u l l l e n g t h r u ns of c a b l e . Tile c a b l e s s h o u l d b e p l a c e d a t t h e b o t t o m o f t h e s aw
c a t s a n d an c ho r ed w i t h r u b b e r o r p l a s t i c w edges o r w i t h n on - co r ro s iv e m e t a l c l i p s .
There i s n o n ee d f o r s e p a r a t i o n o f c a b l e s when more t h a n o n e c a b l e i s p l a c e d i n t h e s ame
c u t . The w ed ges o r c l i p s s h o ul d b e s pa c e d a p p r o x i m a t e ly on e m e t r e a p a r t e x c e p t t h a t
c l o s e r s p a c i n g may be d e s i r e d a t pavem ent j o i n t s , saw c u t i n t e r s e c t i o n s , a n d e n t r a n c e s
t o s p l i c e chambers o r l i g h t s . C ab le s s h ou ld be en ca se d i n f l e x i b l e t u b i n g of
p o ly e th l en e o r o t h e r s u i t a b l e m a t e r i a l of n o t l e s s t h a n 0 .3 m et re i n l e n g t h a t j o i n t s i n
t h e pa ve m en ts . The s i z e of t h e t u b i n g s h o u l d b e s u f f i c i e n t t o a l l o w movem ent o f t h e
c a b l e s . The t u b i n g s h ou l d b e c e n t e r e d on t h e j o i n t a nd t h e e n d s of t h e t u b i n g w r a p p e d
w i t h t a p e t o p re v en t t h e e n t r a n c e of s e a l i n g m a t e r i a l s .
4 .5 .5 .5 S e a l i n g t h e saw c u t . The s aw c u t s h o u l d b e s e a l e d w i t h s u i t a b l e a d h e s i v e
compounds a l o n g t h e e n t i r e l e n g t h a f t e r t h e c a b l e s a r e i n s t a l l e d . The compounds a r e-u s t i a l l y two-component l i q u i d t y p e s s u i t a b l e f o r t h e c a b l e i n s u l a t i o n a nd t h e t y p e of
conc r e te . Tes t sample s o f t he sea la n t shou ld have a minimum e l on ga t i on o f 45 pe r c en t .
The adh es iv e components sh oul d no t be o ld er tha n recommended by t he m anu fac tur er and
s h o u l d n o t b e s t o r e d w he re t h e t e m p e r a t u r e e x c e ed s 30°C o r t h e m a n u f a c t u r e r ' s
recommendations. The m a n u fa c t ur e r 's i r ~ s t r u c t i o n s h o ul d b e f o l lo w ed i n m i xi n g and
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i n s t a l l i n g . U s ua l ly i f t h e a d h e s i v e co mpo ne nts a r e p r e v a r m e d t o 25OC b e f o r e a n d d u r i n g
m ix in g, t h e compound may b e s a t i s f a c t o r i l y i n s t a l l e d an d cu r e d w i t h o u t t h e a p p l i c a t i o n
o f e x t e r n a l h e a t i f t h e a mb ie nt t e mp e r a tu r e i s 7OC o r g r ea t e r . The j o i n t s o f pavement
i n t h e a r e a s o f saw c u t s s h o u l d b e pa ck ed w i t h r o v i n g m a t e r i a l s u c h a s h emp, j u t e ,
c o t t o n , o r f l a x t o p re v en t t h e s e a l i n g m a t e r i a l f r om f lo w in g i n t o t h e o pe n j o i n t . A l l
s u r p l u s a n d s p i l l e d m a t e r i a l s h o u l d be r emoved.
4 .5 .5 .6 C ab le t e r m i n a t i o n s . C ab le s s h o u ld b e p r o p e r l y t er m i n at e d i n f i x t u r e s ,
t r a n s f o r m e r e n c l o s u r e s , a n d s p l i c e ch am be rs . The e n t r a n c e s t o t h e s e t e r m i n a t i o n u n i t s
s h o u l d b e s e a l e d . The t e r m i n a t i o n e n d s o f t h e c a b l e s s h o u l d b e s u i t a b l y c o n n e c te d a n d
t h e c a b l e p r o t e c t e d f ro m m o i s tu r e e n t e r i n g t h e c a b l e b etw ee n t h e c o n d u c t o r a n d t h e e n d
o f t h e i n s u l a t i o n .
4.5.6 C abl e mark i ng
4.5.6.1 A l l c a b l e s an d c a b l e r o u t e s s h ou ld b e marked f o r e a s y i d e n t i f i c a t i o n i n t h e
f u t u r e .
4 .5 .6 .2 C a bl e t a g g i n g . A l l c a b l e s s h o u l d b e t a g g e d i n e a c h m an ho le o r h a n d h o le w i t h
n o t l e s s t h a n two t a g s p e r c a b l e , o n e n e a r e a c h d u c t e n t r a n c e h o l e . T a gs s h o u l d b e
a t t a c h e d t o t h e c a b l e i mm ed ia te ly a f t e r i n s t a l l a t i o n . C ab le t e r m i n at i o n s a nd p ot h ea d s
s h ou l d b e t ag g ed a s t o f u n c t i o n , f a c i l i t y w hic h i t s e r v e s , a n d o t h e r p e r t i n e n t d a t a .
T ag s s h o u l d be of s u i t a b l e s i z e a n d t h i c k n e s s , p r e f e r a b l y o f c o p p er . They s h o u l d b e
s e c u r e l y a t t a c h e d t o t h e c a b l e u s i n g n y lo n co rd . M ark in g o f t a g s s h o u l d c o n s i s t of a n
a b b r e v i a t i o n o f t h e name of f a c i l i t y o r f a c i l i t i e s s er v e d by t h e c a b l e , t h e l e t t e ri n d i c a t i n g t h e t y p e of s e r v i c e (p ow er , t e l e p h o n e, c o n t r o l an d r a d i o f r e qu e n c y ( c o a x ) )
p r o v i d e d b y t h e c a b l e . W here t e l e p h o n e t y p e c a b l e i s u se d f o r c o n t r o l f u n c t i o n s , i t
shou l d be marked a s a c o n t r o l c a b l e , n o t a t e l e p h o n e c a b l e . Where two o r m ore i d e n t i c a l
c a b l e s are u se d t o s e r v e t h e same f a c i l i t y , t h e y may b e b u n dl e d u n d er o n e t a g .
4 .5 .6 .3 C a bl e r o u t e m a r ke r s. D i r e c t e a r t h - b u r i a l c a b l e r o u t e s s h o u l d b e m ar ke d
e v e r y 6 0 m e t r es a l o n g t h e c a b l e r u n, a t e a c h c ha n ge o f d i r e c t i o n o f t h e c a b l e , a nd a t
e a c h c a b l e s p l i c e w it h a c o n c r e t e s l a b m ar ke r of s u i t a b l e s i z e a nd t h i c k n e s s i % e s e
m ar ke rs sh o u ld b e i n s t a l l e d s h o r t l y a f t e r t h e f i n a l b a c k f i l l of t h e c a b l e t r e n c h . The
m ar ke rs s h o u l d be i n s t a l l e d f l a t i n t h e g r ou nd w i t h t h e t o p a p p r ox i ma t el y 2.5 c m above
t h e f i n i s h e d g r a d e, A f t e r t h e c o n c r e t e m ar ke r h a s s e t a minimum of 2 4 h o u r s , t h e t o p
s u r f a c e s h oi ll d be p a in t e d b r i g h t o r a n ge w i t h p a ir i t s u i t a b l e f o r un c ur ed e x t e r i o r
c o n c r e t e . E ac h c a b l e m a rk e r s h o u l d h a v e t h e f o l l o w i n g i n f o r m a t i o n i m p r e s s e d u p on i t s
t o p s u r f a c e :
a ) t h e word "CABLE" o r "SPLICL" . The l e t t e r d es i g na t i ng t h e t y p e of c a b l e
s p l i c e d s h o u l d p r e c e d e t h e word " SPL ICE" ;
b ) t h e name o f t h e f a c i l i t y s e r v e d ;
c ) t h e t yp e o f c a b l e i n s t a l l e d sh o u l d b e marked w i th "POWEK", "CONTROL","Tk3LEPHONE", o r "COAXIAL", o r w i t h s u i t a b l e a b b r e v i a t i o n s f o r t h e s e
t e rm s . The d e s i g n a t i o n of a l l t y p e c a b l e s i n s t a l l e d s h o u l d b e shown o n
t h e m a r k e r ;
d ) a rr ow s t o i n d i c a t e t h e d i r e c t i o n o r ch an ge o f d i r e c t i o n o f t h e c a b l e
r u n ;
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e ) t h e l e t t e r s s ho ul d n o t be l es s th an 10 cm hi gh , 7 c m w i d e a n d 1 c m d e e p ;
f ) c a b l e s i n s t a l l e d i n d u c t o r c o n du i t s h ou l d h av e c a b l e m ar ke rs i n s t a l l e d
e v e r y 60 met re s and a t e v e r y c ha ng e i n d i r e c t i o n of c a b l e , e x c e pt
m ar ke rs s h o ul d n o t b e i n s t a l l e d i n c o n c r e t e o r a s p h a l t s u r f a c e s ; a nd
g ) m an ho le s a nd h an d h o l es s h a l l be i d e n t i f i e d by p u r p o se .
4 .5.7 E n c l o s u r e s f o r c o n n e c t i o n s
4.5.7.1 I n s t a l l a t i o n of e n c l o s u r e s . Most c a b l e c o n n e ct i o ns t o t h e i s o l a t i n g
t r a ns f o rm e r s a r e i n t ra n s f or m e r en c l os u r e s, i n ba s es f o r l i g h t i n g f i x t u r e s w hic h a r e
b elo w t h e s u r f a c e a t t h e e d g e o f p av ed r un wa ys o r t a x i w a y s , o r i n t h e p a ve me nt .
P r e fe r a bl y , t h e s e e n cl o s ur e s a r e i n s t a l l e d a t t h e d e si g n a te d l o c a t i o n s i n a poured
c o n c r e t e f o u n d a ti o n wh ic h e n c as e s t h e e n c l o s u r e c o n t a i n e r b y n o t l e s s t h a n 1 0 t o 1 5 cm
o f c o n c r e t e ar o un d t h e b ot t om a nd s i d e s . M e t a l c o n d u i t s c o n ne c te d t o e n t r a n c e s o f t h e
c o n t a i n e r f o r a dm i t t i n g t h e c a b l e s o f t h e c i r c u i t s h o ul d e x te n d t hr o ug h t h e c o n c r e t e
w a l l s . T h es e c o n d u i t s s h o u l d b e p r o v i d e d w i t h c la mp s f o r c o n n e c t i n g t h e g r o un d w i r e s o r
c o u n t e r p o i s e s . The t o p o f t h e c o n t a i n e r m ust be l e v e l a n d a t t h e p r o p e r d e p t h be lo w t h et o p s u r f a c e of t h e c o n c r e te f o r mo un ti ng t h e l i g h t f i x t u r e o r c o v e r p l a t e . A h o l d i n g
d e v i c e o r j i g s h o u l d b e u s ed t o ma i n ta i n l e v e l , a l i gn m e n t, a nd p ro p e r d e p t h of t h e t o p
o f t h e e n c l o s u r e c o n t a i n e r d u r i n g i n s t a l l a t i o n an d c u r i n g of t h e c o n c r e t e . The e nd s of
c a b l e s a r e p u l l e d i n t o t h e e n c l o s u r e c o n t a i n e r a nd t h e e n d of t h e c o n d u i t o u t s i d e t h e
c o n c r e t e f o u n da t i on i s s e a l e d a r ou n d t h e c a b l e w i th a s u i t a b l e compound t o k e e p t h e
e n c l o s u r e f r e e o f w a t e r . The e l e v a t e d l i g h t s , s em i -f l us h l i g h t s , o r b l a n k c o v e r s
m ou nt ed o n t h e s e c o n t a i n e r s s h o u l d i n c l u d e a g a s k e t o r o t h e r means o f s e a l i n g t o p r e v e n t
w a t er f r om e n t e r i n g t h e c o n t a i n e r .
4.5.7.2 I n s t a l l a t i o n i n e x i s t i n g pave men t. I f l i g h t s a r e t o b e i n s t a l l e d i n
e x i s t i n g p av em en ts , i n s t a l l i n g t h e t r a n s fo r m e r e n c l o s u r e s i n c o n c r e t e f o u n d a t i o n s may
n o t b e p r a c t i c a l . U s ua l ly t h e t r a n s f o r m e r e n c l o s u r e i s l o c a t e d a t t h e e d g e o f t h e
pavement a nd t h e s ec on da ry c a b l e s t o t h e l i g h t a r e i n s t a l l e d i n saw c u t s . A t r a n s f o r m e r
e n c l os u r e, j u n ct i o n bo x, o r t h e l i g h t f i x t u r e may be i n s t a l l e d a t t h e l o c a t i o n f o r t h e
l i g h t f o r m aking t h e c o n n e c t io n s t o t h e l i g h t by b o r in g a h o l e of t h e p r o p e r s i z e an d
d e p t h i n t h e p av em en t. The l i g h t f i x u t r e may b e m ou nt ed o n a n e n c l o s u r e o r b e o f a t y p e
s u i t a b l e f o r i n s t a l l i n g d i r e c t l y i n t h e h ol e. H ol es of p r op er d i am e te r f o r r h e f i x t u r e s
o r e n c l o s u r e s s h o u l d b e b o r e d i n t h e p av em en t w i t h d ia mo n d- ed g ed b i t s . T he b ot t o m o f
t h e h o l e f o r j u n c t io n b ox es a nd l i g h t E i xt u re s s h o u ld be f l a t o r s l i g h t l y c on ca ve e x c e pt
t h a t a n a r e a 2 .5 cm w id e a ro un d t h e p e r i m e t e r s h o u ld b e f l a t , I f t h e h o l e s a r e d r i l l e d
t o o d e e p, t h e y s h o ul d b e f i l l e d w i t h s e a l a n t compound t o t h e d e s i r e d d e p t h a n d t h e
compound p e r m i t t e d t o c u r e b e f o r e p r o c e e d in g w i t h t h e i n s t a l l a t i o n .
4.5.7.3 I n s t a l l i n g t h e e n c l o s u r e . The s i d e s a nd b o t t om o f t h e t r a n s f o r m e r
e n c l o s u r e , j u n c t i o n b ox, o r f i x t u r e s h o ul d be s a n d b l a st e d im me d ia te ly p r i o r t o
i n s t a l l a t i o n . A ls o s a n d b l a s t t h e i n s i d e f a c e s o f t h e b o r e d h o l e . The b o t t o m a n d s i d e s
o f t h e e n c l o s u r e o r f i x t u r e a nd t h e f a c e s a n d bo tt om o f t h e b o r ed h o l e s h o u l d be c o v er e d
w i t h a c o a t i n g of a s u i t a b l e s e a l a n t w i t h a minimum am ou nt t h a t w i l l c om pl et el y f i l l t h e
s p a c e b e tw e en t h e c o n c r e t e a n d t h e f i x t u r e o r e n c l o s u r e . 'L'he s e a l a n t c om pou nd i s
us ua l l y a t w o- pa r t p as t e compound w hi ch i s mixed a nd i n s t a l l e d i n a cc o r d an c e w i t h t h e
m a n u f a c t u r e r ' s i n s t r u c t i - o n s . A h o l d in g d e v ic e o r j i g s h o u ld be u s ed f o r i n s t a l l i n g e a c h
l i g h t o r e n c lo s ur e t o a s s u r e i t s p r o p e r e l e v a t i o n a nd a l i g n m e n t . The h o l d i n g d e v i c e
s ho ul d be l e f t i n p ln c e u n t i l t h e s e a l a n t h as s e t - The c a b l e s s h o u ld b e p u l l e d i n a nd
b ro ug ht i n t o p o s i t i o n f o r c o n n ec t in g o r s p l i c i n g a s r e q u i r e d a nd t h e e n t r a n c e s ho ul d b e
qe a i e d . A l l s u r p l u s s e a l a n t o r embedding compound should be re:noved.
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4.5.7.4 D i r ec t - bu r i al i s o l a t i n gt r a n s f o r m e r s d e p t h a s t h e c a b l e s c o n n ec t e d t o
t h e t r a n s f o r m e r s . T r an s fo r m er s a nd c a b l e s s h o u l d b e a r r a n g e d s o t h a t t h e r e w i l l be no
b en ds o r s t r e s s e s o n t h e c o n n e c t o r s , a n d t h e c a b l e s a nd l e a d s s h o u l d be p r o v i d e d w i t h
s l a c k t o a ccom modate e a r t h s e t t l i n g an d f r o s t h e av es . Use p rope r con nec to rs and t ap e
t h e o u t s i d e j o i n t w i t h 2 o r 3 t u r n s o f e l e c t r i c a l ta pe . Do n o t make s p l i c e s f o rc o n n ec t i ng t h e c a b l e s t o t h e t r a n s f o r m e r s .
4.5.7.5 I n s t a l l i n g i s o l a t i n g tr a n sf o r m er s i n t r an s f or m e r e n c lo s u re s . When i s o l a t i n g
t r a n s f o r m e rs a r e i n s t a l l e d i n t r an s f or m e r e n cl o s ur e s , t h e t r a ns f o rm e r s s h o u l d be
p o s i t i o n e d w i t h a f l a t s i d e o n t h e b ot to ms of t h e e n c l o s u r e s , i f p o s s i b l e . C on nec t t h e
c a b l e s t o t h e l e a d s of t h e t r a n sf o r m er s us i n g s u i t a b l e c o n ne c to r s, n o t s p l i c e s , and t a p e
t h e j o i n t s . C on ne ct or s s h o ul d l i e f l a t on t h e b ot to ms of t h e e n c l o s u r e s w i t h o u t b en di ng
o r t e n s i o n i f p o s s i b l e . Ground co n n e ct i o ns on i s o l a t i n g t r a n s f o r m e r s s h o u l d b e
c o nn e ct e d t o t h e g ro un d w i r e i f s u c h c o n n ec t i on s a r e p r ov i de d . I f t h e i n t e r n a l te mp er a-
t u r e s i n t h e e n c lo su r es w i l l be more th an 120°C, a s ec t i o n of a lurninum f o i l be tween th e
l i g h t f i x t u r e s and t h e t ra n s fo r m e rs w i l l r e du c e t h e e f f e c t s o f t h e h e a t on t h e
t r a n s f o r m e r .
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W m S OR UPJD UND SERVICE AT AEELODROaS
5.1 FEATURES OF THE CABLES
5 .1 .1 .1 I n s u l a t i o n . The f o l l o w i n g i n s u l a t i o n m a t e r i a l s a r e commonly s p e c i f i e d
b e c a u se t h e y p r o v i d e t h e maximum r a t e d c o n d u c t o r t e m p e r a t u r e s f o r o p e r a t i n g , o v e r l o a d ,
a n d s h o r t - c i r c u i t c o nd i .t i on s f o r c a b l e s r a t e d up t o a maximum o f 3 5 k i l o v o l t s :
a ) C ros s - l i nked p o l ye t hy l ene (XLP). Th i s t he rmo- se t t i ng compound ha s
e x c e l l e n t e l e c t r i c a l p r o p e r t i e s , good c he mi ca l r e s i s t a n c e , good p h y s i c a
s t r e n g t h c h a r a c t e r i s t i c s , a n d r em ai ns f l e x i b l e a t low t e m p e ra t u re s .
b ) E t h y l e ne - p r o py l e n e r u b b e r (E PR ). T h i s compound h a s e l e c t r i c a l p r o p e r -
t i e s w hi ch a r e c o n s id e r e d e q u a l t o c r o s s- l in k e d p o l y e t h y l e n e ; t h e r e-
f o r e , t h e c o n t r a c t o r s h o ul d be g iv e n t h e o p t i o n t o p r o v id e e i t h e r t y pe .
5 .1 .1 .2 The f o l l o w i n g i n s u l a t i o n m a t e r i a l s may b e u s e d w he re s p e c i a l c i r c u m s t a n c e s
w a r r a n t t h e i r l o we r r a t e d c o n d u c t o r t e m p e r a t u r es o r t h e i r l o we r r a t e d maximum v o l t a g e
c l a s s .
a ) Ru bb er. R ub ber i n s u l a t e d c o n d u c t o rs p r o v i d e e a s e o f s p l i c i n g , g oo d
m o i s tu r e r e s i s t a n c e , a nd low d i e l e c t r i c l o s s e s .
b ) V a r n i sh e d c a m b r ic . V a r n is h e d c a m b r ic i n s u l a t i o n i s u se d f o r r e s i s t a n c e
t o o zo ne an d o i l and f o r e a s e of s p l i c i n g . Use v a r n i s h e d c a m b r ic p r i n -
c i p a l l y i n c on jl an ct io n w it h p a p e r i n s u l a t e d c a b l e wh er e o i l m i g r at i o n i s
a p ro bl em , Where i n s t a l l e d i n w et o r h i g h l y h umid l o c a t i o n s o r un d er -
g r o u n d , v a r ni s h e d -c a m b r ic i n s l i l a t i o n m us t b e p r o v i d e d w i t h a s u i t a b l e
s h e a t h .
P a p er i n s u l a t e d . Use p a p e r i r l s u l a t e d c a b l e f o r low i o n i z a t i o n , l o n g
l i f e , h i g h d i e l e c t r i c s t re n g t h , low d i e l e c t r i c l o s s e s , a nd good s t a b l e
c h a r a c t e r i s t i c s u n d er t e m p er a tu r e v a r i a t i o n s . A s w i t h v a r n is h e d - ca m b r ic
i n s u l a t i o n , p ap er i n s u l a t i o n r e q u i re s a s u i t a b l e p r o t e c t i v e m e t a l l i c
s h e a t h . I t may b e s p e c i f i e d a s a n o p t i o n when e x i s t i n g c a b l e s a r e p a p e
i n s u l a t e d , o r as a r e q u ir e m e n t when t h e e x t r a c o s t i s j u s t i f i e d b e ca us e
n e i t h e r c r o s s -l i n k ed p o l y et h y l en e o r e t h y l e n e - p r o p y l e n e r u b b e r p ro v i d e
t h e r e q u ir e d q u a l i t i e s .
d ) B u t y l r u b b e r . T h i s t h er m os e t t in g i n s u l a t i o n h a s h ig h d i e l e c t r i c
s t r e n g t h a nd i s h i g h l y r e s i s t a n t t o m o i s tu r e , h e a t , a nd o z on e. T t can
b e u s e d up t o 3 5 k i l o v o l t s , b u t h a s l o we r r a t e d c o n d u ct o r t e m p e r a t u r e st h a n e i t h e r c r o s s - l in k e d p o l y e th y l e ne o r e th y l e ne - p r op y l e n e r u bb e r.
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e ) S i l i c o n e r u b b e r. T h is t h e r m o s e t t i n g i n s u l a t i o n i s h i g h l y r e s i s t a n t t o
corona . It c a n b e u se d i n w e t o r d ry l o c a t i o n s ,
e xp o se d, o r i n c o n d u i t. I t h a s t h e h i g h e s t r a t e d c o n d uc t or t e m p e r a t u r e s
b u t c a n be u s ed o n ly f o r a p p l i c a t i o n s up t o f i v e k i l o v o l t s .
5 .1 .1.3 Cable sh ea th s
a ) N on m et al li c. N o nm e ta ll ic s h e a t h s s h o u l d b e f l e x i b l e , m o i s t u r e r e p e l -
l a n t , a nd l o n g l a s t i n g . N eo pr en e, w h ic h i s o f t e n u s ed as n o n m e t a l l i c
c a b l e s h e a t h s , i s u n s u i t a b l e i n many l o c a t i o n s . T h is mate r i a l f r e -
q u e n t l y a b s o r b s e x c e s s i v e a mo un ts o f w a t e r w h i ch may p e n e t r a t e t h r o u g h
t o t h e i n s u l a t i o n . Some n o n m e t a l l i c s h e a t h m a t e r i a l s , e s p e c i a l l y i n
some t r o p i c a l a r e a s , a re r ep or t ed t o be damaged by mi c ro -o rgan i sms ,
i n s e c t s , a nd p l a n t l i f e . Some s h e a t h mater ia l s , w h ic h p e r f o r m w e l l
w he re i n s t a l l e d u nd er gr ou nd o r i n c o n d u i t s , d e t e r i o r a t e r a p i d l y i f
i n s t a l l e d wh ere i t i s e xp o se d t o s u n l i g h t . M a t e r i a l s w hi ch become b r i t -
t l e a t low t e m p e r a t u r e s s h o u l d n o t b e u se d i n c o l d r e g i o n s . In some
l o c a t i o n s , r o d e n t s f r e q u e n t l y damage n o n m e t a l l i c - s h e a t h e d c a b l e . I n
t h e s e a r e a s t h e c a b l e sh o ul d be i n s t a l l e d i n d u c t s o r m e ta l li c -s h ea t he dc a b l e s h o u l d b e u s e d *
b ) M e t a l l i c . C a bl e s e x po se d t o m e c ha n ic a l damage o r h i g h i n t e r n a l p r e s s u r e
r e q u i r e a m e t a l l i c s h e a t h , s u c h a s l e a d , a luminurn, o r s t e e l . C e r t a i n
i n s u l a t i o n s , s u ch as p a p e r a nd v a r n i s h e d c a m b r ic , r e q u i r e s u c h
p r o t e c t i o n i n a l l c as es .
5 .1 .1 .4 Cable cov er in gs . A s u i t a b l e c o v e ri n g o r j a c k e t may be r e q u i r e d f o r
c o r r o s i o n p r o t e c t i o n o f m e t a l l i c s h e a t h s .
5 .1 .1 .5 S h i e l d e d c a b l e s . S h i e l d i n g o f a m e d iu m v ol ta g e d i s t r i b u t i o n c a b l e i sr e qu i re d t o c o nf in e t h e e l e c t r i c f i e l d t o t h e i n s u l a t i o n i t s e l f and t o p re v en t l ea ka ge
c u r r e n t s from r e ac h in g t h e o u t s i d e s u r f a c e of t h e c a b l e . I n s u l a t i o n s h i e l d i n g i sr e q u i r e d o n a l l n o n m e ta l l ic - s h ie l d e d c a b l e r a t e d t wo k i l o v o l t s a n d ab ov e, e x c e p t f o r
a er od ro m e- li gh t i ng s e r i e s - c i r c u i t c a b l e s , a nd a l l m e t a l l i c -s h e a th e d c a b l e r a t e d f i v e
k i l o v o l t s a nd a bo ve . S h i e l d s s h o u l d b e g ro u nd e d t o r e d u c e t h e h a z a r d s o f s h o c k .
tirouttding i s r e q u i r e d a t e a c h t e r m i n a t i o n , o t h e r w i s e d an ge ro u s i n du c e d s h i e l d v o i t a g e s
may occur.
5 .1 .1 .6 C a b l e f i r e p r o o f i n g . C a b le s i n m a n ho l es , h a n d h o l e s , and t r a ns f o rm e r v a u l t s
o p e r a t i n g a t 2 40 0 v o l t s o r o v e r, o r ex po se d t o t h e f a i l u r e o f o t h e r c a b l e s o p e r a t i n g a t
t h e s e v o l t a g e s , s h o u l d b e f i r e p r o o f e d w i t h a s u i t a b l e s p r a y c o a t i n g . E x c e p ti o n s may b e
made wh ere p h y s i c a l ~ e p a r a t i o n , s o l a t i o n by b a r r i e r s , o r o t h e r c o n s i d e r a t i o n s pe rm it .
5 .1 .1 .7 P r o t e c t i o n a g a i n s t c o ro n a damage. I n s u l a t i o n o f h i g h v o l t a g e c a b l e s w hi ch
may b e d am ag ed by o zo n e s h o u l d b e p r o t e c t e d a g a i n s t t h i s d am ag e by c o n t r o l l i n g c o r o n a ,
w h ic h p ro d u c e s o z on e , b y p l a c i n g a t h i n s e m i - c o n d u c t i n g f i l m b e tw e e n t h e c o n d u c t o r a nd
i t s i n s u l a t i o n . T h is f i l m f i l l s t h e v o id s betwe en t h e co nd u ct or an d t h e i n s u l a t i o n th u s
p r e v e n t i n g t h e g e n e r a t i o n of c o r o n a a n d h e n ce o zo n e . ( S e e 5. 1. 3. 6. )
5 .1 .1 .8 Cable con duc tors . Annealed coppe r i s u s e d i n m os t fo r ms of i n s u l a t e d c on -
d u c t o r s b e ca us e o f i t s h i g h c o n d ~ t c t i v i t y , l e x i b i l i t y , a nd e a s e of h a n d li n g . Medium-
h a r d d r a w n c o p p e r has g r e a t e r t e n s i l e s t r e n g t h t h a n s n n e a l e d c o p pF r , Aluminure c on -
d u c t o r s may be p e r m i t t e d a s a c o n d u c t o r P s o p t i o n e x c e p t wh er e c o r r o s i v e c o n d i t i o n s l i m i t
t h e i r tL sage;
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Classes o f s e r v i c e
5.1.2.1 L o w v o l t a g e c a b l e s -- i n s u l a t i o n r a t e d a t 600 v o l t s o r
l e s s -- a r e u se d t o co nn ec t t h e s e c on d a r ie s of s e r i e s / s e r i e s i s o l a t i n g transformers t o
t h e lamps i n t h e f i x t u r e s , f o r l o w v o l t a g e d i s t r i b u t i o n c i r c u i t s , an d as l o w v o l t a g e
f e e d er c i r c u i t s t o s i n g l e u n i t s an d t h e s h o r t e r c i r c u i t s . The co nd uc to rs a re u s u a l l yc o p p e r b u t may be al um in um , a nd e i t h e r s i n g l e - o r m u l t i - c o n d u c t o r c a b l e s a r e u s e d . Both
s o l i d an d s t r a n d e d c o n d uc t o rs a r e u s e d b u t s t r a n d e d i s p r e f e r r e d i f f r e q u e n t f l e x i n g o f
t h e c a b l e i s e x p e c t e d . The c r o s s s e c t i o n a l a r e a o f t h e c on d u ct o r may v a r y f r om 2 mm2 t o28 mm o r l a r g e r i f n e ce s sa r y t o d e c re a s e t h e v o l t ag e d ro p .
5 .1 .2.2 H i gh - vo l ta g e c a b l e s . F o r a er od ro m e l i g h t i n g , h i g h v o l t a g e c a b l e s a r e u s e d
m o s tl y f o r s o u r c e power d i s t r i b u t i o n a nd f e e d e r c a b l e s . The c r i t e r i a a nd mater ia ls a r e
t h e s a m e as f o r power d i s t r i b u t i o n c a b l e s d i s c u s s e d i n p a r a g ra p h s 2.5 .5 t o 2.5 .7. The
v o l t a g e s u s e d u s u a l l y r a ng e fr om 1 0 00 t o 5 000 v o l t s . C on du ct or s i z e s u s u a l l y a r e i n
t h e ran ge of 3 .3 mm2 t o 21 mm2 i n c r o s s s e c t i o n b u t l a r g e r s i z e s a r e o c c a s i o n a l l y us ed .
T h e se c a b l e s may b e e i t h e r s i n g l e - c o n d u c t o r o r two- o r t h r e e - c o n d u c t o r c a b l e s . C o n s i d e
t h e s o i l , e nv ir on me n t, m ethod o f i n s t a l l a t i o n , s u b j e c t i o n t o c h em i ca l s, a n d a ny s p e c i a l
p ro bl em s i n s e l e c t i n g t h e i n s u l a t i o n , j a c k e t s , s h e a th i n g , a nd s h i e l d i n g f o r t h e s ec a b l e s .
5 .1 .2 .3 S e r i e s a er od ro me l i g h t i n g c a b l e s . The r e q u ir e m e n ts o f t h e c a b l e s f o r t h i s
p u r p o se h a v e b e en s t a n d a r d i z e d m ore t h a n h a v e t h e c a b l e r e q u i r e m e n t s f o r m o st power
c i r c u i t s . The s e r i e s c u r r e n t u se d i n t h e s e c i r c u i t s i s between 6 and 20 amp ere s. The
condu c t o r s i z e commonly us ed i s 8.4 mm 2 i n c r o s s - s e c t i o n b u t some 3. 3 mm2 c a b l e i s a l s o
u s e d . T h es e c a b l e s a r e s i n g l e - c o n d u c t o r . The c o n d u c t o r i s u s u a l l y s t r a n d e d b ut s o l i d
c o n d u c to r c a n a l s o b e u se d. T he i n s u l a t i o n i s u s u a l l y 5 O O O vo l t r a t e d . A n o n - m e t a l l i
j a c k e t o v e r t h e i n s u l a t i o n i s commonly u s e d . M e t a l l i c - t a p e s h i e l d i n g b e t w e en t h e i n s u l -
a t i o n a n d j a c k e t o r b et we en t h e j a c k e t a n d n o n - m e ta l l ic c o v e r i n g i s o f t e n u s e d b u t may
n o t b e r e q u ir e d f o r some i n s t a l l a t i o n . The p r e f e r r e d s e r i e s - l i g h t i n g c a b l e s a r e
s t r a n d e d , c o p p e r , 8.3 mm2 c o n d u c t o r ; c r o s s - l i n k e d p o l y e t h y l e n e , e t h y le n e - p ro p y l e n e- r u b -
b e r , o r b u n a r u b b e r i n s u l a t i o n ; c h l o ro s u l fo n a t ed p o ly e t h yl e n e , p o l yv i n y l c h l o r i d e ,
p o l y e t h y l e n e , o r h ea vy d u t y n e o p r en e j a c k e t e d ; m e t a l- t a p e s h i e l d e d t y p e s .
5.1.2.4 C o nt r ol c a bl e s. C o nt ro l c a b l e s a r e l o w v o l t a g e c a b l e s u s u a l l y i n p a i r s o r
mul t i -condi ic tor . A g r o u p o f s i n g l e - c o n d u c t o r c a b l e s may be u s e d f o r so me s i m p l e c o n t r o
c i r c u i t s . Some c o n t r o l c a b l e s h av e o ne o r two l a r g e r c o n du c t o rs f o r t h e l i n e v o l t a g e
a n d /o r n e u t r a l an d s e v e r a l s m a l l e r c o nd uc to rs f o r t h e i n d i v i d u a l c o n t r o l s , O th er
i n s t a l l a t i o n s may u s e a p a i r o f l a r g e r w ir e s f o r t h e l i n e an d n e u t r a l and o t h e r c a b l e s
w i t h many s m a l l e r c o n d u ct o r w i r e s f o r t h e i n d i v i d u a l c o n t r o l s . M u lt i -c o nd u c to r c o n t r o l
c a b l e s h a v e 7 , 12 , 1 6 , o r many m ore c o n d u c t o r s a r e u s e d . M ost c o n t r o l c a b l e s h a v e
s t r a n d e d co p p er co n d u c to r s . T he s i z e o f t h e c o n d u c to r i s s e l e c t e d tc:, k e e p t h e l i n e
v o l t a g e d r o p w i t h i n a n a c c e p t a b l e r a n g e. The c r o s s s e c t i o n a l s i z e of t h e c o n d uc t or s i s
u s u a l l y b e t w e e n 3 . 3 mm2 and 0.5 mm2. The i n s u l a t i o n r e s i s t a n c e r a t i n g must be s u i t a b l e
f o r t h e c o n t r o l v o l t a g e w hich i s u s u a l l y 250 v o l t s o r l e s s . Ru bb er, p o l y e t h y l e n e , p ol y-
v i n y l c h l o r i d e , v a r n i s h e d c am b r ic , a n d p a p e r a r e some of t h e t y p e s o f i n s u l a t i o n f o r
c o n t r o l c a b l e s . T hin i n s u l a t i o n i s d e s i r a b l e t o r ed uc e t h e d i am e te r of t h e c a b l e .
T w i s te d p a i r s o r s p i ra 1 . i ng o f t h e c o n d u c t o r s i s d e s i r a b l e f o r a l t e r n a t i n g - c u r r e n t con-
t r o l c i r c u i t s t o re du ce t h e i nd u ce d v o l t a g e b etw een c i r c u i t s . M u lt i- co nd u ct or c a b l e s
m us t h a v e a n o u t s i d e j a c k e t a n d may be s h i e l d e d w i t h metal t a p e .
5,1,2,5 C or mn un ic ati on s c a b l e . S p e c i a l i n te r co ~ n mn u n ic a ti o n s o r t e l e p h o n e c i r c u i t s
s h o u l d b e i n s t a l l e d t o p r ov id e communications b etw ee n c o n t r o l t ow er , l i g h t i n g v a u l t s ,
a nd o f f i c e s o r s t a t i o n s , The c i r c u i t s a r e u s u a l l y o n e o r inore t w i s t e d - p a i r t el ep h or se
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t y p e c a b l e s . T hes e c a b l e s s h o ul d be s u i t a b l e f o r un de rg ro un d i n s t a l l a t i o n . Al though
t h e c o n t r o l c a b l e s may be u se d f o r c o m m n ic a t io n s a t some i n s t a l l a t i o n s , s e p a r a t e c a b l e s
i n s e p ar a t e co nd ui ts o r w e l l s e p ar a te d i n t h e t r e n c h, i f d i r e c t b u r i a l , a r e p r e f e r re d .
5.1.2,6 Ground wi re s. A g ro un d w i r e o r c o u n t e r p oi s e w i r e s h ou l d be i n s t a l l e d t o
p r o t e c t u n de r gr o un d power a n d c o n t r o l c a b l e s f r o m h i g h g r o un d c u r r e n t s u r g e s i n a re aswhere damage f rom l ig h t n i ng s t r i k e s may be expec ted . The gr ou nd w i r e s h o u l d b e i n s t a l -
l e d b e tw ee n t h e e a r t h ' s s u r f a c e an d t h e u n de rg ro un d c a b l e s . It i s u s u a l l y a n u n i n s ul -
a t e d , s t r a n d e d co p pe r c o nd u c to r . The s i z e of t h i s gr ou nd w i r e s ho u l d b e n o t l e s s t h a n
t h e l a r g e s t s i z e c o n du c to r s w hi ch i t p r o t e c t s . C r o s s - s e c t i o n a r e a o f t h e c o n d u c t o r may
range f rom 8.4 mm2 t o 21 mm2 o r l a r g e r . It s h o u l d b e a c o n t i n u o u s c o n d u c t o r a n d
c o nn e ct ed t o e a c h f i x t u r e , l i g h t b a s e , a nd gr ou nd r o d o r c o n n ec t i on a l o n g i t s r o u t e .
5.1.3 Causes of ca bl e damage
5.1.3.1 C ab le f a u l t s a r e f r e q u e n t r e as o n s f o r a er od ro me l i g h t i n g c i r c u i t f a i l u r e s
a nd o f t e n r e q u i r e c n s i d e r a b l e t im e and e f f o r t t o l o c a t e and r e p a i r . E f f e c t i v e m ethods
o f r e d u ci n g c a b l e f a u l t s im pr ov e r e l i a b i l i t y of t h e sy s te m . B e t t e r k no wl ed ge o f t h e
c a u s e s o f damage t o c a b l e s h o u l d a i d i n c h o o s i ng t y p e s of c a bl e and i n s t a l l a t i o np rocedure s . Some o f the se cause s a r e d i s cus sed be low .
5 .1 .3 .2 Mechanica l damage. P robab ly mos t c a b l e f a u l t s a r e c aused by mech an ica l
damage. Poor i n s t a l l a t i o n t e chn ique s and p rocedure s a r e p robab ly th e most common cause
of m e c ha ni ca l damage, b u t f r o s t he av e s, v i b r a t i o n f r om a i r c r a f t o r v e h i c l e t r a f f i c ,
r o d e n t s , g ro un d s h i f t i n g o r s e t t l i n g , a nd many o t h e r r e a s o n s may p h y s i c a l l y d am age t h e
ca bl e. Some ty pe s of mechanical damage a r e :
a ) N ic ks an d s c r a p e s of t h e i n s u l a t i o n .
b ) Over s t r e s s i n g of t h e c a b l e when p u l l i n g i n t o d u c t s o r u n r o l l i n g t h e
c a b le f o r d i r e c t b u r i a l .
c ) S to ne s o r f o r e i g n o b j e c t s i n t h e be ds o r b a c k f i l l s of t r e n c h e s .
d ) I n ad e qu a te s l a c k a t e nt r a n c e s t o o r i n s i d e o f h a nd h ol es , m a n ho le s, l i g h t
b a s e s , c o n d u i t s , f i x t u r e s , c o n ne c t io n s t o e q ui p me n t, c o n n e c t o r s ,
s p l i c e s , a lo n g t r e nc h e s o r c o n du i t , o r o t h e r l o c a t i o n s where s e t t l i n g ,
m a in t en a nc e, i n s t a l l a t i o n s , o r w e at h er may i n c r e a s e s t r e s s e s .
e ) N ick ing of t h e c o nd u ct o r a t s p l i c e s o r c o n n e c to r j o i n t s may l a t e r b r ea k
t h e c o n d u c t o r .
f ) I na de qu at e s e p a r a t io n of c a b l e s i n t r e n c h es , e i t h e r v e r t i c a l l y o r h o r i -
z o n t a l l y , a t s l a c k l o o p s of c a b l e , o r p l a c e s w here e a r t h co m pa ct io n o r
f r e e z i n g a c t i o n may f o r c e t wo s e c t i o n s o f c a b l e i n t o d i r e c t c o n t a c t .
g ) F re ez in g o r f r o s t he av es f o r c i n g t h e c a b le a g a i n s t i c e , f r o z e n e a r t h , o r
an y o t h e r s o l i d o b j e c t o r m a t e r i a l . P ro pe r c u sh i on in g a nd s l a c k t o
r ed uc e s t r e s s a t t h e s e p o in t s i s n e c e s s a r y .
h ) I m p ro p er l y s u p p o r t e d c a b l e s i n m an ho le s o r o t h e r a r e a s w h er e s a g g i n g o r
e x p o s u r e may r e s u l t i n o b j e c t s o r p e r s o n s p u tt L ng p r e s s u r e o n t h e c a b l e .
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i ) V i b r a t i o n fr o m t r a f f i c p a s s i n g o v e r t h e c a b l e o r f r o m e qu ip me nt o p e r a -
t i o n a t t a c h e d t o o r n e a r t h e c a b l e may c a u se f a t i g u e o f t h e c o n d uc t o r o
o f t h e j a c k e t a nd i n s u a l t i o n . W here s u c h c o n d i t i o n s may e x i s t o r b e
d ev el op ed , i n s t a l l t h e c a b l e s i n d u c t s wh ic h e x t en d w e l l b eyond t h e a r e
o f v i b r a t i o n .
j ) B r ea k in g o r s e p a r a t i o n o f c o n d u i t s o r d u c t s may b r e a k t h e c a b l e . The
i n s t a l l a t i o n of t h e d u c t s a nd co n d u i t m ust b e p r o p e r l y j o i n e d a nd
s u i t a b l y b a c k f i l l e d a n d tam ped.
5.1.3.3 Wate r pene t ra t ion . A g r o u n d f a u l t i s formed when water i s a b l e t o p e n e t r a t
t h r ou g h t h e c a b l e s h e a t h a nd i n s u l a t i o n t o t h e c on du ct or . W at er p e n e t r a t i o n o r l e a k a g e
may o c c ur a t s p l i c e s , c o n n e c t io n s , c a b l e t e r r d i i a t i o n s , p h y s i c a l damage a r e a s , s n s a t i s -
f a c t o r y i n s u l a t i o n , p i n ho l e s f ro m l i g h t n i n g o r o v er v o l t a g e , o r o t h e r d e f e c t s .
a ) I mp ro pe rl y made s p l i c e s a nd i m p r o pe r l y i n s t a l l e d c o n n e c t or k i t s a r e a
f r e q u e n t s o u r c e o f w a t e r p e n e t r a t i o n . S ee S e c t i o n 5.2 f o r i n s t r u c t i o n s
f o r m aking s p l i c e s and i n s t a l l i n g c o nn e c to r s .
b ) I n o r d e r t o av o id w a t e r p e n e t r a t i o n a t t h e en ds of c a b l e , t h e s e e n d s
s h ou l d be k e p t c l e a n a nd f r e e f r om m o i s tu r e b e f o r e a s w e l l a s a f t e r
c o n n e c t i n g t o t h e e q u i pm e nt . The e n d s of s p a r e c a b l e s s h o u l d b e
s i m i l a r l y p r o t e c t e d . Some t y p e s o f i n s u l a t i o n , e s p e c i a l l y p a p er a nd
m i n e ra l f i l l e d , may a t t r a c t m o i s tu r e fr om t h e a t m os ph er e d u r i n g p e r i o d s
o f h igh humid i ty . The ends o f the cab l e s of t he se type s shou ld be ke p t
s e a l e d a t a 1 1 t im e s e ve n a f t e r c on n ec ti n g t o t h e e qu ip m en t.
c ) Some i n s u l a t i o n s , e i t h e r f ro m d e f e c t s o r composition, may perm it ex ces -
s i v e w a te r p e n et r at i on . Q u al i t y t e s t s of i n s u l a t i o n r e s i s t a n c e s h o ul d
d e t e c t s u c h d e f e c t s . T he re a r e r e p o r t s t h a t some n e o p re n e -j a ck e t ed
c a b l e i s n ot a d e qu a te ly wa te r r e s i s t a n t , a l th o u gh o t h e r r e p o r t s s t a t e
t h a t c a b le of t h i s t y p e p er fo rm s w e l l . B e fo r e c a b l e i s p u r c h a s e d , t h ep er fo rm an ce o f t h e t y p e of c a b l e a t o t h e r i n s t a l l a t i o n s , p r e f e r a b l y f ro m
t h e s ame m a n uf a c t u r e r , s h o u l d be i n v e s t i g a t e d .
d ) L i g h t n i n g s t r i k e s may s e v e r i y dam age c a b l e s o r t h e i n d u c e d v o l t a g e s m ay
b e en ou gh t o d amage t h e i n s u l a t i o n by c r e a t i n g p i n h o l e s . T h e s e p i n h o l e s
a r e more l i k e l y t o o cc u r a t p o i n t s o f c r o s s i n g c a b l e s o r wh er e t h e c a b l e
i s n e a r o r i n c o n t a c t w i t h m e t a l c o n du c t or s . P r o p e r l y i n s t a l l e d g ro un d
w i r e o r c o u n t e r p o i s e s s h o u ld r e du c e t h e d amage f ro m l i g h t n i n g s t r i k e s .
e ) E x ce s si v e v o l t a g e may be a p p l i e d t o a c a b l e , e i t h e r a c c i d e n t a l l y o r f r o m
f a u l t y o p e r a t i o n . Damage t o t h e c a b l e may n o t b e n o t i c e a b l e
immedia te ly .
5.1.3.4 Chemical damage. O ft en a ero dr om e l i g h t i n g c a b l e s a r e l o c a t e d i n a r e a s w h er e
f u e l , o i l , a c i d s , o r o t h e r c h em i ca ls may b e p r e s e n t r e g u l a r l y o r o c c a s i o n a l l y . T he se
c h e m ic a l s a f f e c t t h e i n s u l a t i o n r e s i s t a n c e of some t y p e s o f c a b l e s . I f i t i s known, o r
s u s p e c t e d , t h a t c a b l e s may b e e x po s ed t o s u c h c i l em i c a ls , s e l e c t a t y p e o f c a b l e w hi ch i s
r e s i s t a n t t o t h e s e ch em ic al s.
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5.1.3.5 I n some a r e a s , d i r e c t b u r i a l c a b l e i s damaged by roden t s ,
e s p e c i a l l y g t h e i n s u l a t i o n . T he re i s some e v i d e n c e t h a t t h e r o d e n t s may
be a t t r a c t e d t o t h e c a b l e e i t h e r b y t h e h e a t e m it t e d f ro m i t o r by i t s t a s t e . Where
rodent damage i s a s e r i o u s p ro bl em , it may be d e s i r a b l e t o i n s t a l l t h e c a b l e i n d u ct s o r
t o u s e m e t a l s h e a t h e d c a bl e ,
5 .1 .3 .6 M ic ro -o r ga n is m o r p l a n t d am ag e. M i cr o -o r g an i sm s a n d p l a n t s a r e r e p o r t e d t o
h a ve damaged some t y p e s o f c a b l e s i n t r o p i c a l o r s u b t r o p i c a l a r e a s . O t h e r t y p e s of
c a b l e a r e n o t s e r i o u s l y a f f e c te d . I f i t i s a n t i c i p a t e d t h a t s u c h p ro b le ms may o c c u r ,
s e l e c t a t y p e o f c a b l e wh i ch i s known t o b e r e s i s t a n t t o s u c h m i cr o -o r ga n is m s a nd
p l a n t s .
5.i.3.7 Ozone and corona damage. Some c a b l e i n s u l a t i o n s a r e d am ag e6 b y o z o n e a n d
t h u s by t h e c or on a p ro du ce d by t h e c i r c u i t o r by n e ar by c i r c u i t s . C a bl e i n s u l a t i o n s a r e
a v a i l a b l e which s a t i s f a c t o r i l y r e s i s t t h e se e f f e c t s . S e l ec t c a b le s w i t h t h e s e q u a l i t i e s
i f t h e c ab l e i s c a r r y i n g h i g h v o l t a g e s o r may be e xp o se d t o o t h e r s o u r c e s o f o z on e o r
c o ro n a . I n t h e p a s t some S t a t e s ha v e u s e d c a b l e s w hi ch w er e n o t p r o t e c t e d a g a i n s t
c o r o n a dam ag e f o r r un wa y a nd a p p r o a ch l i g h t s e r i e s s y s t em s r e a so n i n g t h a t t h e s e s ys te ms
a r e o pe r a te d a t f u l l i n t e n s i t y f o r o n l y a r e l a t i v e l y s m a l l number o f h o u r s p e r y e a r .
C o n s e q u e n t l y , t h e s e c a b l e s a r e s u b j e c t e d t o h i g h -v o l t ag e s t r e s s d u r i n g o n l y a s m a l l
f r a c t i o n oE t h e t i me i n s e r v i c e . T h is p r a c t i c e h a s be en fo un d t o be u n d e s i r a b l e s i n c e
t h e r e d u c t i o n i n c o s t i s sm a l l a nd b e ca u s e some o f t h i s c a b l e i n v a r i a b l y i s i n s e r t e d
i n t o t h e power d i s t r i b u t i o n c i r c u i t s a nd a r e s u bj e ct ed t o c on ti nu ou s h i g h v o l t a g e
s t r e s s .
5.1.3 .8 U l t r a v i o l e t da mag e. Some c a b l e i n s u l a t i o n , w h ic h p e rf o rm s s a t i s f a c t o r i l y i n
u nd er gr ou nd i n s t a l l a t i o n s , may become b r i t t l e a n d d e t e r i o r a t e r a p i d l y w he re e x po se d t o
s u n l i g h t i f u s ed o n e l e v a t e d s u p p o r t s s u c h as a p pr o ac h l i g h t t ow er s. I f t h e c a b le w i l l
r ec e. iv e t h i s s o r t of e xp os ur e, s e l e c t c a b l e w i th i n s u l a t i o n wh ic h r e s i s t s u l t r a v i o l e t o r
i n s t a l l t h e c a b le i n me ta l c on du i t .
5,! .3 ,9 Ca ble d e t e r i o r a t i o n , Nosh c a b l e I n s u l a t i o n d e t e r i ~ r z t e s l o w ly -s e r v i c e L i f e o f u n de r gr o un d c a b l e s s h o u l d be 1 0 t o 20 y e a r s .
5 .2 CABLE CONNECT ION S
5 .2 .1 C a b le s p l i c e s
5.2.1.1 A l l c a b l e s p l i c e s s h o u l d b e pe r fo r me d by e x p e r i e n c e d a n d q u a l i f i e d c a b l e
s p l i c e r s u s i n g h ig h s t a n d a r d s o f w ork ma Sls hip . S p l i c i n g m et ho ds a n d m a t e r i a l s s h o u l d be
o f t y p e s r ecommended by t h e m an u f a c tu r e r o f t h e s p l i c i n g m a t e r i a l f o r t h e p a r t i c u l a r
t y p e o f c a b l e b e in g s p l i c e d . A 1 1 c a b l e s p l i c e s s h o u ld meet t h e f o l l o w i n g r e q u i r e m e n t s .
5 .2 .1 .2 Power c a b l e s i n s u l a t e d f o r m ore t h a n 5 000 v o l t s . S p l i c e k i t s d e s i gn e d f o r
t h e t y p e of c a b l e b e i n g s p l i c e d s h o u l d b e u s ed . When s u c h k i t s a re n o t a v a i l a b l e , t a p ed
s p l i c e s m ade i n a c c o r d an c e w i t h p a r a g r a p h 5.2.2 may be u s ed . Epoxy o r r e s i n s p l i c e s
s h o u l d n o t b e u s e d .
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5 .2 .1 .3 Power c a b l e s w i t h 610- t o 5 0 0 0- vo lt i n s u l a t i o n . P r e s s u r e e p o x y - r e s i n
s p l i c e s e nv el op e s an d c a s t s p l i c e k i t s d es ig ne d f o r t h e c a b l e s h o ul d be u s e d i n s t r i c t
c on fo rm a nc e w i t h t h e m a n u f a c t u r e r " i n s t r u c t i o n s . Taped s p l i c e s s h o u l d b e u s ed o n l y i f
n e c e s s a r y .
5.2.1.4 Power c a b l e s i n s u l a t e d f o r 6 00 v o l t s o r l e s s . Cast s p l i c e k i t s o r p r e s s u r e
e po xy -r es in s p l i c e e nv el op es s u i t a b l e f o r a l l d i r e c t e a r t h - b u r i a l c a b l e may b e us ed .-Taped s p l i c e s u s i n g p r e s t r e t c h e d o r h e a t - s h r i n k a b l e t u b i n g as a c o v e r i n g may a l s o b e
used.
5.2.1.5 C o n t r o l a nd t e l e p h o n e c a b l e s . A t y pe of r e - e n t e r a b le f i l l e d s p l i c e e nv el op
i s a v a i l a b l u l a t e d n o n- p re s su r iz e d c a b l e s . S p l i c e s t o
e x i s t i n g p r e s su r i ze d , l e ad - co v e re d , o r p a p e r - i n s u l a t e d c a b l e s s h o u l d b e lil c c o r d a n c e
w i t h t h e r e q u i re m e n t s of t h e a u t h o r i t y i nv o lv e d.
5 .2 .2 Taped s p l i c e s
5.2.2.1 Taped s p l i c e s a r e u s u a l l y u s ed o n l y when s a t i s f a c t o r y c o n n e c t o r s a n d s p l i c e
k i t s c a nn o t be o b t a in e d . I f t a p ed s p l i c e s a r e t o b e made, t h e c o r r e c t t e c h n i q u e mu st b
used i n o r d e r t o o b t a i n s a t i s f a c t o r y s e r v i c e . The t e c h n i q u e d e s c r i b e d b e l ow i s i n t e n d e
f o r si n gl e -c o n du c to r c a b l e b u t a p p l i e s w i th s u i t a b l e a d a p t i o n t o m u lt i- c on d u ct o r c a b l e
s p l i c e .
5 .2 .2 .2 Keep t h e e n d s o f t h e c a b l e s t o b e j o i n e d c l e a n a n d p r o t e c t e d f r o m m o i s t u r e
a t a l l t i m e s .
5 .2 .2 .3 C a r e f u l l y t a p e r a nd remove t h e c o v e r i n g , j a c k e t , m e t a l l i c s h i e l d , s h e a t h ,
a n d i n s u l a t i o n f r o m t h e e n ds o f t h e c a b l e s t o be jo i n e d . Remove a l l t r a c e s of i n s u l a-
t i o n f ro m t h e c o n d u c to r s f o r a l e n g t h o f a p pr o xi m at e ly 2 cm b e i n g v e r y c a r e f u l n o t t o
n i c k t h e c o n d u c to r , S mo ot hl y t a p e r t h e i n s u l a t i o n b a ck f r om t h e c o n d u c t o r f o r 2 cm o r
more. Remove t h e s h e a t h , m e t a l t a p e , j a c k e t , e t c . b a ck a l o n g t h e o u t e r s u r f a c e of t h e
i n s u l a t i o n l a y e r f o r an a d d i t i o n a l 2 c m ( s e e F i gd z e S - la ), T h i s o f f s e t o f t h e t a p e r i n gs h o u l d b l o c k p a t h s of w a t er p e n e t r a t i n g a l o n g t h e t a p e r i n g . Keep i n t a c t t h e metal t a p e
f o r s h i e l d i ng , i f i n vo lv ed , o v e r t h e e n t i r e l e n g th o f t h e s p l i c e . S i m i l a r l y , t a p e r t h e
n o n m e t a l l i c s h e a t h f o r 2 cm o r more. Remove any s t e e l o r m e t a l a rm or o r o u t e r metal
c o v e ri n g b u t l e a v e s t u b s o r e nd s f o r r e c on n e c t i n g a c r o s s t h e s p l i c e .
5.2.2.4 Use a c ri mp -t yp e c o n n e c to r t o j o i n t h e e n d s o f t h e co n d u c to r . Crimp t h e
c o n n e c t o r o n t o t h e e n d s of t h e c o n d u c t o r s u s i n g a t o o l d e s i g n e d t o make a comple te cr imp
b e f o r e t h e t o o l c a n be re mov ed ( s e e F i g u r e 5 - l b ) . The c o n d u c t o r c o n n e c t o r may a l s o b e
s o l d er e d i f d e s i re d .
5.2.2.5 U si ng r u bb e r o r s y n t h e t i c r u b b e r t a p e of g o od q u a l i t y , c a r e f u l l y w rap t h e
j o i n t o ne l a y e r a t a t i me m a i n t a i n i n g en ou gh t e n s i o n o n t h e t a p e f o r a p p r o x i m a t e l y 2 5
p e r c e n t e l o n g a t i o n a nd o v e r l a p p i n g t h e t a p e a p p r o x im a t e ly 5 0 p e r c e n t o f i t s w i d t h .E a c h l a y e r w i l l e x te n d f u r t h e r up t h e t a p e r a l o n g t h e i n s u l a t i o n . C o nt in u e t h i s b u i ld -
up of l a y e r s o f r ub b er t a p e t o t h e f u l l s i z e of t h e i n s u l a t i o n l a y e r . Se e F i g u re 5 -l c-
5 .2 .2 .6 I f s h i e l d i n g t a p e i s u se d o v e r t h e i n s u l a t i o n , c o nn e ct t h e meta l t a p e , w h i c
s h ou l d h av e b ee n k e p t i n t a c t , a c r o s s t h e s p l i c e by s o l d e r i n g o r u s i n g s u i t a b l e
c o n n e c t o r s . Wrap w i t h e x t r a m e t a l t a p e o f s i m i l a r t y p e i f n ee de d.
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(a) T A P E R I N G I N S U L A T I O N .
CONNECTOR*
* A t t a c h w i t h a t o o l de s i gne d t o make a c om pl e te c r im p be f o r e t he
t o o l can be r emoved.
( b ) CONDUCTOR CONNECTION.
T W E A T HE R -R E S IS T A NT P L A S T I C T A P E
R U B B E R I N S U L A T I O N T A P E 2I n d i c a t e t a p e l a y e r s a re wound i n b o t h d i r e c t i o n s
( c ) C R OS S S E C T I O N O F SPLICE.
:r r g u r e 5-i. s p l i c e of s~ .ng ie -conduc to r c a b l e
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5.2.2.7 C o nt in ue t o w ra p t h e r u b b e r t a p e a s i n 5 . 2 . 2 , 5 t o n o t l e s s t h an 1.5 t i m e s
t h e d i am e t e r o f t h e c a bl e . C a r e f u l l y ap p l y t e n s i o n on t h e t a p e t o p r e v e n t an y v o i ds a nd
o b t a i n g ood a d h e s io n t o t h e c a b l e s u r f a c e s a nd e a c h i n s i d e l a y e r o f t a p e .
5.2 .2 .8 Over t h e r ub b e r t a p e , a dd s e v e r a l l a y e r s o f h i g h - i n s u l a t i o n - re s i s t an ce ,
f l a m e - r e ta r d a n t , w ea th er - a nd c o l d - r e s i s t a n t t a p e . A pply t h e p l a s t i c t a p e w i t h a p p r e c i -
a b l e t e n s i o n a nd o v e r l a p p i n g e a c h t u r n by a p p r o x i m at e l y 5 0 p e r c e n t o f i t s width . The
p l a s t i c t a p e s ho u ld ex t en d f o r 3 cm o r m ore a l o n g t h e s u r f a c e o f t h e i n s u l a t i o n o f
s h e a t h on ea ch s i d e of t h e s p l i c e .
5 .2 .2 .9 I f t h e c a b l e h a s a s t e el - a r m o r o r o t h e r m e t a l l i c co v e r , c o n n e ct a l e n g t h o f
g ro un di ng b r a i d a c r o s s t h e s p l i c e an d f a s t e n t o t h e ar mor o n t h e c a b l e w i t h s u i t a b l e
c la mp c o n n e c to r s a n d / or s o l d e r o n e a c h s i d e o f t h e s p i i c e s ( s e e F i g u r e 5 -2 a) . If t h e
c a b l e i s l e a d e n ca s e d, make a s u i t a b l e w ip ed -l ea d j o i n t o v e r t h e s p l i c e t o p r ov i d e a
w a te rp r oo f s e a l t o t h e l e a d c o v e r i n g o n t h e c a b l e . I f t h e m et a l c o v e r i n g i s p r o t e c t e d
f ro m c o r r o s i on by a c o a t i n g , a p pl y a c o a t i n g of s i m i l a r m a t e r i a l o v e r t h e e n t i r e s u r f a c e
o f t h e c a b l e and s p l i c e i n t h e a r e a o f t h i s w ork.
5.2.3.1 Use o f co n n ec t o r k i t s . I n r e c e n t y e a r s mo st s e r i e s - c i r c u i t c o n n e c ti o n s h a v e
b e en made u s i n g c o n n e c to r k i t s . A l th o ug h t h e c o s t of c o n n e c t o r k i t s i s s i g n i f i c a n t , t he
t im e s a ve d i n i n s t a l l a t i o n a nd t h e e a s e w i t h w ic h c i r c u i t s c an b e o pen ed a n d r e c l o s ed
when l o c a t i n g f a u l t s ha v e made t h e i r u s e d e s i r a b l e . S i n c e t h e l e a d s o f m o st i s o l a t i n g
t r a n s f o r m e r s a r e now m a nu f ac t ur e d w i t h c o n n e c t o r s , c a b l e c o n n e c t o r s a r e r e q u i r e d an d
p r o v i d e a n e a s y means of c o n n e c t in g o r d i s c o n n e c t i n g t h e t r a n s f o r m e r i n t o t h e s e r i e s
c i r c u i t an d t o t h e l i g h t . S i ng l e- c on d uc t or c o n n e c t o rs a r e shown i n F i g u r e 5-3.
5 .2 .3 .2 I n s t a l l a t i o n of c o n n e c t o r s . The c a b l e e n ds s h o u l d b e p r e p a r e d c a r e f u l l y i n
a c co r d an c e w i t h t h e i n s t r u c t i o n s , k e e pi n g b ot h t h e c a b l e en d s an d t h e c o n n e c t o r s u r f a c e s
f r e e of d i r t an d m o i s t u r e , Make c e r t a i n t h a t a ny c a v i t i e s b et w e en . th e c a b l e a nd
i n i e t i o r o i t h e c on ne ct or a r e f i l l e d w i t h t h e g e l p ro vi de d CO p r e v e n t v o i d s . A f t e rj o i n i n g t h e c o nn e ct o rs e n s u r e t h a t a i r i s n o t t r a p p e d w h ic h may t e n d t o f o r c e t h e c on -
n e c t i o n a p a r t . T ap in g o ve r t h e j o i n t w i t h v i n y l e l e c t r i c t a p e t o keep t h e a r e a c l ea n
and f ro m s e p a r a t i n g i s sugges ted .
5.2.4 C o a x i a l c a b l e s
5.2.4.1 N o n- p re s su r iz e d c o a x i a l c a b l e s . C o a x i a l c a b l e s h o u l d b e j o i n e d u s i n g a p p r o -
p r i a t e c o a x i a l c o n n e c t o rs . E ac h c o n n e c t o r s h o u l d b e c o v er e d w i t h a 1 5 cm minimm le ng th
of h e a t s h r i n k a b l e t u b in g h a v in g a 3 : 1 o r h i gh e r s h r i n k r a t i o . A s u i t a b l e s p r ay c a b le
a d h e s i v e may be s p r a y e d o n t h e c a b l e b u t n o t t h e c o n n e c t o r p r i o r t o s h r i n k i n g . A f lame-
l e s s h e a t g un s ho u ld be us ed f o r s h r i n k i n g t h e h e a t s h r i n k a b l e t u b in g . An a l t e r n a t e
c o v e r i n g may b e p r e s t r e t c h e d , m e c h a n i c al l y s h r i n k a b l e t u b i n g a p p l i e d as recommended by
t h e m a n u f a c t u r e r .
5 .2 .4 .2 S p l i c e s i n p r es s u ri z ed c o a x i al c a b le s . No f i e l d - i n s t a l l e d s p l i c e i n
p r e s s u r i z e d c o a x i a l c a b l e s h ou l d be a l lo w ed u n l e s s s p e c i f i c a l l y a u t h o r i z e d .
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I--- V I N Y L P L A S T I C T A P E A NC HO R F O R B R A I D
METAL ARMOR
SOLDER F I L L E L E C T R I C A L G RO UN D B R A I D
R U B B E R I N S U L A T I O N T A P E
( a ) C O N N EC TI NG ARMOR AC R O SS TH E S P L I C E
W E A T H E R - R E SI S T A N T P L A S T I C T A P E
( 4 L A Y E R S - 1 / 2 L A P P E D , W I TH L I Q U I D
E L E C T R I C A L C O A T IN G A P P L I E D )
(b) O U T E R C O V ER I NG O F T HE S P L I C E
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(a) FACTORY MOLDED PLUG
(b) F A C T O R MO LD ED R E C E P T A C L E
PIN-
- _ -
M E T A L S O C K E T
MIN 2 SAW SLOTS
SOCKET
OPTION& INTERN OPTIONAL INTER
L O m I NG BESIGH LbCRlNG DESIGN
( c ) F I E L D A T T A C H ED C O NN E CT O RS
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5.2.5 Connection of con duc tor s
5.2.5.1 Power cond ucto rs . Connect ions of ca bl e cond uctor s sho uld be made us in g
c ri mp c onne c t o r s u t i l i z i n g a c r i m p ing t o o l de si gne d t o make a c om pl et e c ri m p be f o r e t h e
tool can be removed. S p l i t - b o l t c o n n e c t o rs may b e u s ed f o r l o w v o l t a g e c i r c u i t s o f 60 0
v o l t s o r l e s s .
5 .2 .5 .2 C on t r o l a nd t e l e phone c a b l e s . J o i n i ng o f t e l e phone o r c o n t r o l c onduc t o r s
should be done w i th a t w i s t e d and s o l d e re d s p l i c e o r a n a p p r o p r i a t e s e l f - s t r i p p i n g ,
p r e i n s u l a t e d c o n n ec to r i n s t a l l e d w i t h t h e s p e c i f i c t o o l d e si g ne d t o c ri mp t h e c o n ne ct o r.
C o lo r c od i ng o f t he c onduc t o r s s hou l d be fo l l ow e d t h roughou t t he i n s t a l l a t i on .
5.2.5.3 Cable armor and sh ie ld s . Armor sh ie l d s s hou l d b e e l e c t r i c a l l y b on de d a c r o s s
t h e s p l i c e by c l e a n i n g a nd s o l d e r i n g . Use s e c t i o n s of m e t a l b r a i d a nd c o n d uc t i n g t a p e ,
i f ne ede d. Armor a nd s h i e l d i ng s hou l d be c om pl e te l y i n s u l a t e d f r om e a c h a nd f r om
ground, e xc e p t a s no t e d i n pa r a g r a ph 4 .5 .3 .3 .
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