Protections and interlocks for 210 MW LMW turbines P.Christopher, AEE / C&I / MTPS TURBINE PROTECTIONS : Condenser V ac! "er# $o% . Trine $e oi$ "er# $o%. A'ia$ shi(t hi)h. These are the three !ain protections (or *+M- M- trines. A$$ these trippin) are e!anatin) (ro! trine re$a# pane$. 1. Condenser vacuum pr ot ect ion: Condenser "ac! is essentia$$# reired (or creatin) a stea! ($o% in the trine and it 0eeps the e'hast hood te!peratre nder contro$. I( "ac! drops e$o% the set "a$e , %hich !a# case increase in PT e'hast hoo d te!peratre raise. The PT $ades are shrn0 (itted %ith the sha(t. 1e to the increase in e'hast hood te!peratre the PT $ades !a# )et $oosen and starts "i ratin) and the PT !a# )et da!a)ed. I( "ac! decreases there !a# not e a s((icient stea! ($o% and hence the nit $oad cannot e !aintained. T o a"oid the trine $ades (ro! (ai$re, the "ac! protection is "er# !ch essentia$. Nor!a$$# the "ac! is !aintained arond 2 34!! 5). I( "ac! drops to 2 36!!, "ac! $o% %i$$ e annnciated to a$ert the operator to ta0e necessar# !easres to i!pro"e the "ac!. I( "ac! (r ther drop s to 7 68!! , trip co!!and %i$$ e init iated to trip the tr ine i!!ediate$#. T o a"oid (rea0ish trippin), t%o ot o( three $o)ic is adopted (or ensrin) the "ac! "er# $o% condition. Nor!a$$# pressre s%itches are ein) sed (or sensin) the "ac! $o% and "ac! "er# $o%. B# 0eepin) the "ac! protection s%itch in the test position , the protection can e chec0ed drin) the nit is in rnnin) condition. I( the protection s%itch is 0ept in test position the trine %i$$ not e trip (or "ac! "er# $o% protection. 9"ac! protection ot: %i$$ e annnciated %hi$e the protection s%itch is in test position. The $o)ics sed (or Vac! protection in trine re$a# pane$ is )i"en e$o% .;or eas# nderstandin) the $o)ics are represented # ($o% chart $oc0 dia)ra!. 1
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Protections and Interlocks for 210 MW LMW Turbines
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7/26/2019 Protections and Interlocks for 210 MW LMW Turbines
* / > $o)ic in OP1R pane$ =.AR 8 7 this re$a# )et ener)i@ed %hen "ac! drops to 2 36 !! o( 5) thro)h PS *. 9Vac! $o%: %i$$ e annnciated thro)h this re$a#.AR 6B & 6C 2 "ac! protection read# circit.AR 3 7 "ac! "er# $o% protection re$a#, %hich %i$$ )et ener)i@ed thro)h the contacts o( AR >? & AR 6C
re$a#s. Be(ore "ac! p$$in) the re$a#s AR >? & AR 8 are in ener)i@ed condition ecase there is no "ac!in the condenser. AR 6A, 6B & 6C are in de ener)i@ed condition. -hi$e "ac! p$$in)< the "ac! is raisin)(ro! at!ospheric pressre to 7 36 !! o( 5) = re$a#s AR >? and AR 8 )et de e)ner)ised. Theannnciations 9Vac!! $o% 9 and 9 Vac!! protection ot 9 %i$$ )et reset.-hi$e the nit is in trippedcondition and there is n "ac! in the condenser 9 Vac! "er# $o%: %i$$ not e annnciated .Theannnciation (or "ac! protection ot is deri"ed (ro! one o( the contact o( "ac! protection ot s%itch , %hich is in para$$e$ %ith the N/C contact o( AR 6A.5ence 9 "ac! protection ot 9 %i$$ e annnciated tho)hthe protection ot s%itch is in ON condition.
-hen AR 8 )et deener)ises and thro)h its N/C contact AR 6A & AR 6B )et ener)ise. AR 6B is ati!er re$a# VTT ++ < de$a#ed pic0 p = its contact c$oses a(ter a preset ti!e. In or case it is set at * secondsand hence , the contact o( AR6B )et c$oses a(ter a ti!e de$a# o( * seconds. Thro)h the contact o( AR6B the
re$a# AR 6C )et ener)ise.AR 6C is a ti!er re$a# VTT+* < de$a#ed drop ot = its contacts c$oses i!!ediate$#a(ter the spp$# e'tended to the re$a# and a(ter spp$# ct ot its contact opens a(ter a pre set ti!e de$a#. Inor case it is set at * seconds.
In the circit <(i) *=AR>+ is a N/C contact o( AR>+ re$a# %hich c$oses %hen MSSV is in opencondition and AR +6 A is the N/C contact o( AR +6 A %hich c$oses %hen ESV & IV are in open condition.These are para$$e$ contacts .Once the ro$$in) is started contact AR+6A %i$$ )et c$oses and e(ores#nchroni@ation contact AR >+ %i$$ )et c$oses < a(ter openin) o( MSSV=.
Prot -out
$w.
Reset
nit "'n.
AR)3
AR+ AR1 AR1)A
AR),
AR)3
AR7
AR6AR)3AR),AR)AAR+AR7
P"1 P"2
AR 6
AR7
22* D3
7/26/2019 Protections and Interlocks for 210 MW LMW Turbines
-hi$e nit is rnnin) the re$a#s AR6A, AR 6B & AR 6C %i$$ e in ener)i@ed condition. On ener)isationthe ($a) %i$$ e in (a$$en condition inAR6A & AR6B t in AR 6C the ($a) %i$$ e in reset condition.
< (i) 2 > =
I( the protection s%itch is in ON condition and the c$osin) o( N/O contacts o( AR 3 $eads toener)isation o( TR 1 < Trine oc0ot Re$a# = and thro)h its contacts TTS < Trine Trip So$enoid = %i$$)et ener)i@ed to trip the trine.
I( the protection s%itch is in test position 9 Vac! Protection Ot: %i$$ e annnciated .I( the AR 6A isin deener)ised condition a$so thro)h its N/C 9 Vac! Protection Ot: %i$$ e annnciated.
Thro)h the N/O contacts o( AR 3 & AR ? , 9 Vac! "er# $o%: %i$$ e annnciated. AR? is a !ana$resettin) re$a#, its ($a) and contacts ha"e to e reset !ana$$#.
“ Reset before cuttin in of !acuum protection"
+
22* D3
AR 1)A
AR7AR6
Vac.Prot.%ut
Annunciation.
AR )A
Prot.out
"w.
TLR D
o
To ener4i$e
TT"
AR 6AR 6
oo
Vac.Ver'.Low
Annunciation.
AR 7
AR 6AR 6
o
+8 Ann. $uppl'
7/26/2019 Protections and Interlocks for 210 MW LMW Turbines
;or an i$$stration .eep the protection s%itch is in test position. AR +6A and AR 6C contacts are inc$osed condition<ESV & IV are in open= .Reset s%itch is nor!a$$# c$osed t#pe, %hi$e resettin) on$# it )ets
open.No% the "ac! is droppin) to 2 68 !! 5). AR >? %i$$ )et ener)ise and its N/O contact )et c$osed,as the AR 6C contact is a$read# in c$osed condition AR3 %i$$ ener)ise and the N/O contacts o( AR 3 )etc$osed t the TR 1 %i$$ not e ener)i@ed and the trine %i$$ not e tripped. A(ter !a0in) correcti"e actions the "ac! is raised to its nor!a$ "a$e or !ore than 2 68!! AR >?)et deener)ised , t de to se$( cei$in) created # the N/O contact o( AR 3 in series %ith reset s%itch the AR3 %i$$ re!ain in ener)i@ed condition and hence the contacts o( AR 3 in series %ith protection ot s%itch are inc$osed condition. In this condition i( %e ct in the "ac! protection the nit %i$$ trip tho)h the "ac! is innor!a$ "ae. I( %e reset, the AR 3 )et deener)ised< de to the re$easin) o( se$( sea$in)= and s%itch on the protections%itch, the nit %i$$ not trip. 5ence a$%a#s re!e!er to reset e(ore ct in the protection s%itch. Thisprocedre has to e (o$$o%ed (or oi$ and A'ia$ shi(t protections a$so.
Causes for vacuum droppin:
• Redced )$and stea! pressre.
• ;ai$re o( eectors de to $o% PR1S stea! pressre.
• Ver# hi)h 5ot %e$$ $e"e$.
• ;ai$re o( coo$in) %ater p!ps.
• 1rains in "ac! s#ste! open to at!osphere & condenser< AS > &8=.
• In)ress o( air to to "ac! s#ste! (ro! $oose ($an)es and instr!ent tappin) points.
PS 2 oi$ pressre s%itch in OP1R pane$ , %hich %i$$ act at .3 sc.
AR 4 , oi$ pressre $o% re$a# , thro)h this 9 oi$ pressre $o%: %i$$ e annnciated and thro)h itscontact ACOP %i$$ )et started at .3 sc.
F6 2Contact pens in case o( po%er spp$# (ai$re to earin) )ear !otor and re!ain c$osed so $on) as po%erspp$# is a"ai$a$e.F3 2 Contact c$oses at the !o!ent o( initiatin) arrin) )ear !otor start p and sha$$ open in the e"ent o(nor!a$ stoppin) o( !otor or stoppin) o( !otor # inter$oc0.F? 2 contact c$oses on ener)i@in) o( arrin) )ear contactor and opens in the e"ent o( nor!a$ stoppin) o(!otor or ato stop.
AR 4 2 oi$ pressre $o% re$a#, thro)h %hich 9 oi$ Pressre o% 9 %i$$ e annnciated and ACOP %i$$e started.
AR *? 2 oi$ protection re$a# , oi$ pressre "er# $o% %i$$ e co!!nicated thro)h its contact (ro! $oi$ pressre "er# $o% pressre s%itch to AR GA and AR GB re$a#s. %hi$e the TD is on arrin) )ear AR *? )etsener)i@ed thro)h F6 & F3 contacts %ith a se$( sea$in) o( AR *4 & AR *? contacts. Once the ESV & IV s areopened this %i$$ ener)i@ed thro)h the contact o( AR+6 A. I( the AR*? is not ener)i@ed , oi$ protection
8
AR28
=)
=7
=6
AR28
AR27
AR1)A
P"1 P"1
AR27AR 8
22* V D3
7/26/2019 Protections and Interlocks for 210 MW LMW Turbines
!a# not act and hence oi$ protection ot %i$$ e annnciated thro)h the N/C contact o( AR *? as sho%ne$o%.
AR *4 2 This is a de$a#ed o(( ti!er re$a#.< VTT +* = This re$a# %i$$ )et ener)i@ed %hen the Barrin) )ear !otoris in ser"ice. oi$ protection is ena$ed thro)h the contacts o( AR *? & AR *4 %hi$e the TD is on Barrin)
AR 8? 2 oi$ protection ot re$a#, I( the protection s%itch is in test position ,AR 8? %i$$ )et ener)[email protected] S%itch 2 Nor!a$$# c$osed 2 %hen the s%itch is trned , the contact )ets open.
Reset this s%itch e(ore cttin) in the $ oi$ protection as said (or "ac! protection.
<
te$t te$ton te$t
nit$'nchroni$e5
Re$et "#
+8VAnn."uppl'.
AR 27
AR +7AR 1*AR <,
P" 2
AR 27
AR <A
22* V D3
AR <A
Prot."#
Lub iol prot. %ut
Annunciation
7/26/2019 Protections and Interlocks for 210 MW LMW Turbines
AR GA & AR GB 7 N/O contacts o( AR GA and AR GB re$a#s respecti"e$#.AR 8? 2 N/ C contacts o( AR 8? re$a#AR 4 2 N/O contact o( AR 4 re$a#.It c$oses to start the ACOP !otor in the e"ent o( $ oi$ pressre drops to
.3 0sc.
CA 3 2 "ac! rea0er 2 AC operated !otori@ed "a$"e,it )ets opened (or $ oi$ and a'ia$ shi(t protections to rin) the TD rotor to the rest position as ic0 as possi$e.
The protection is in 9ON: condition, N/C contacts o( AR 8? in c$osed condition. -hen the $ oi$ pressredrops to .> 0sc AR GA and AR GB )et ener)i@ed. The c$osre o( N/O contact o( AR GA in series %ith contactAR 8? < (i)74= $eads to ener)isation o( TR 1 to trip the trine.The c$osre o( N/O contact o( AR GB in series %ith contact AR 8? < (i)74= $eads to open the "ac! rea0er.
I( the TD is on Barrin) )ear and the $ oi$ pressre drops to .> 0sc , # the openin) o( AR GB N/C contact
the arrin) )ear !otor %i$$ trip.I( the protection is in 9ot: condition , Barrin) )ear !otor %i$ not e tripped asthe para$$e$ contact AR 8? N/O %i$$ )et c$osed %hi$e the protection is ot.;or oth the cases the "ac! rea0er )ets opened.Thro)h the contacts o( AR 4 ACOP )ets started at .3 sc o( $ oi$ pressre.At .6 0sc the 1COP )et started direct$# thro)h the $oca$ pressre s%itch. There is no re$a# (or 1COP.
L$% +&L )''$'C&)#&+'
1*
22* D3
AR +7AR <,
N03/
AR 8
TLR D
AR +7AR +7AR +7AR +7
AR <,AR <,AR <AAR <A
3A
6contactor
11* A3 control $uppl'
To $top
,arrin4 ;ear
motor
To $tartA3L%P
7/26/2019 Protections and Interlocks for 210 MW LMW Turbines
AR4 2 thro)h this contact $ oi pressre $o% %i$$ e annnciated.AR GA & AR + 2 thro)h these para$$e$ contacts oi$ pressre $o% %i$$ e annnciated.
Reset before cuttin “in" t,e protection s-itc, refer fi /
et s ta0e an incident . Protection s%itch is in test position. AR *? contact is in c$osed condition .Reset
s%itch is nor!a$$# c$osed t#pe, %hi$e resettin) on$# it )ets open.
No% the $ oi$ pressre is droppin) to .> 0sc. 1e to the c$osre o( PS * ,AR GA and AR GB %i$$ )etener)ise. The N/O contacts o( AR GA & AR G B )et c$osed. No% de to the protection s%itch is in test positionthe AR 8? )et ener)i@ed and its series contact %ith AR GA & AR GB )et opened and hence the TR 1 %i$$ not )et ener)i@ed and the trippin) o( trine %i$$ e a"oided.
A(ter de"e$opin) the $ oi$ pressre < ao"e .> 0sc= PS* )ets opened .Bt the ARGA & GB %i$$re!ain in ener)i@ed state < se$( sea$in) # AR GA contact=. In this condition i( %e s%itch ON the protections%itch, AR 8? )et deener)ised and thro)h N/C contact o( AR8? and AR GAHs N/O contact <in c$osedcondition= the TR 1 )et ener)i@ed and the trine %i$$ trip.
Once the $ oi$ pressre is nor!a$i@ed, sho$d not (or)et to reset e(ore cttin) IN o( the protections%itch.
.)3ial s,ift protection
11
AR 8AR 1*AR <A
+8 V Annunciation $uppl'
Lub oil Pre$$ure
Low
Annunciation
Lub oil Pre$$ure er'
Low Annunciation
7/26/2019 Protections and Interlocks for 210 MW LMW Turbines
The A'ia$ !o"e!ent o( trine sho$d e %ithin per!issi$e $i!its. I( this $i!it e'ceeds there %i$$ e a da!a)eto the thrst earin) and in %orst case trine !a# )et da!a)ed se"ere$# .In desi)n care is ta0en to 0eep thetrine nder a$anced condition # ad!ittin) the stea! ($o% in opposite directions. 1e to so!e reasonsthere is a chance o( trine sha(t )ettin) !o"ed to either )enerator side <positi"e= or to%ards (ront pedesta$
<ne)ati"e=I( trine sha(t a'ia$$# !o"es # +.?!! ne)ati"e or +.*!! positi"e ,the trine has to e tripped
i!!ediate$#.Vac! rea0er has to e opened to rin) the trine to rest as ic0 as possi$e as said (or$e oi$ protection.
This protection can a$so e tested %hi$e trine is in ser"ice # 0eepin) the protection s%itch in testposition.
The $o)ics sed (or a'ia$ shi(t protection is sho%n e$o%.
>i4 - 1*
)3ial s,ift protection circuit
12
22* D3
AR-2
A?ial
$hi!t
@
te$t
nit
"'n.
A?ial
"hi!tProt. out
!
AR+6
&
&
AR-
A?ial
"hi!t
@i.@i
D
TLR-D
Vacuum ,9r.
%pen
!
Prot."#
in
AXIAL SHIFT PROTECTION
7/26/2019 Protections and Interlocks for 210 MW LMW Turbines
;or an# protection trippin) < inc$din) e'terna$ trips= re$a# TR 1 )et ener)i@ed , thro)h its N/Ocontacts in series %ith AR+6C N/C contact < %hi$e ESV / IV in open condition= and AR +3 the TTS )etener)i@ed and trips the trine< CVSM,ESV and IV )et c$osed=.As soon as the ESV / IV c$osed the AR +6C contact )et open < TR 1 contacts re!ains in c$osedcondition=,+ M Oh! resistor and + M (d capacitor co!e in series %ith trip so$enoid and AR +3. The "o$ta)eacross the trip so$enoid dischar)ed # the + M oh! resistance.As the hi)h resistance is co!e in toseries the crrent ($o%in) thro)h the trip so$enoid and AR +3 %i$$ a$so !ini!i@ed. And hence the tripso$enoid and AR +3 coi$ )et deener)ised.The contact and (a) ha"e to e reset # !ana$.Thro)h the contact o( AR +3 9Trine protection trip: %i$$ e annnciated.
;and trip from $C% :
;or an# e!er)enc# # trnin) the trine hand trip s%itch in the contro$ des0, ** V 1c is direct$# app$ied tothe trip so$enoid in series %ith AR >> and AR +6 C contact and the trine %i$$ )et tripped.
Thro)h the contact o( AR >> 9Trine 5and trip UCB: %i$$ e annnciated.
#urbine local trip:
The trine can e tripped (ro! $oca$ # pressin) the p$n)er in the e"ent o( (ai$re o( e$ectrica$ trippin).1rin) this trippin) 9Trine $oca$ trip: %i$$ e annnciated thro)h AR >* re$a#.
TURBINE TRIPPE1 ANNUNCIATION
2*
AR * 3
AR 17A
22* D3 "uppl'
AR 16 AR AR 2 AR
AR 16
@an5 trip$witch
TLR C DAR 17 ,
Annunciation "uppl'
7/26/2019 Protections and Interlocks for 210 MW LMW Turbines
AR +3 2 Trine protection trip re$a#, (or ener)isation o( TTS thro)h the contacts o( TR 1 the AR +3 )etener)i@ed and thro)h its N/O contact 9Trine protection trip: %i$$ e annnciated.Resettin) the re$a# #!ana$ the annnciation %i$$ )et reset.
AR >> 2 Trine hand trip (ro! UCB. B# hand trippin) the trine (ro! UCB AR >> )et ener)i@ed and thro)hits contact 9Trine 5and trip c: %i$$ e annnciated.B# !ana$ resettin) the ($a) this annnciation %i$ )etreset. AR >* 2 This re$a# )et ener)i@ed thro)h the N/O contact o( AR > C re$a#. Pro"ided AR+3 and AR >> !ste in deener)ised condition. ;or the c$osre o( ESV / IV %ith nit s#nchroni@ed condition re$a# AR > C %i$$)et ener)i@ed.
TRIP CIRCUIT SUPERVISION J
+.* oh! resistance and AR +? B are sed (or sper"isin) the trine trip circit . -hi$e nit is inser"ice AR +?B is in ener)i@ed state. The !a'i!! "o$ta)e drop %i$$ e a"ai$a$e across the re$a# AR +? Bis arond +G4 V .-hen e"er a open circit occrred in Trine trip so$enoid or AR +6 C contact or in AR +3re$a# coi$ , AR +? B )et dener)ised and thro)h its N/C contact re$a# AR +? A )et ener)i@ed and thro)h itsN/O contact 9Trip circit (a$t#: %i$$ e annnciation .-hen the nit is in tripped condition AR +6 C )ets openand AR +? B )et e ener)i@ed and 9 Trip circit (a$t#: %i$$ e annnciated and )et reset a(ter openin) o( ESV
& IV..
$'&# PR+#(C#&+'7
CL)77 “)" #R&PP&'*.
Protections reired i!!ediate iso$ation o( Denerator / Denerator Trans(or!er / Unit A'i$iar# Trans(or!ersare )roped in t he C$ass 9A: trippin). %e can sa# as 9E!er)enc# shtdo%n:. ;or this protections trip i!p$seis instantaneos$# )i"en to the D.T. rea0er thro)h 43 D+, 43 D*& 43 D> )enerator !aster re$a#s and (or
trippin) the trine trip i!p$se is )i"en thro)h the 43 T trine !aster re$a# in DRP.
CL)77 “%" #R&PP&'*.
This t#pe o( trippin) is ca$$ed as 9 Nor!a$ Sht do%n: or non e!er)enc# trippin). Protections o( )enerator (or %hich i!!ediate e$ectrica$ iso$ation is not reired ,Trine protections and Boi$er protections are )roped into this cate)or#.Most o( the Denerator a'i$iar# protections are in c$ass 9B: trippin).
21
AR 2
Turbine protection trip
Turbine @an5 trip
3,
Turbine Local trip
7/26/2019 Protections and Interlocks for 210 MW LMW Turbines