“INSULATORS 101” PRESENTED BY ANDY SCHWALM PRESIDENT – VICTOR INSULATORS, INC. IEEE LIFE MEMBER PRESENTED TO: SWEDE MAY 8, 2014- SAN ANTONIO, TX.

“INSULATORS 101”

PRESENTED BY ANDY SCHWALM

PRESIDENT – VICTOR INSULATORS, INC.IEEE LIFE MEMBER

PRESENTED TO: SWEDEMAY 8, 2014- SAN ANTONIO, TX

WHO DEVELOPED INSULATORS 101?

INSULATOR WORKING GROUP 15.09.09 OF THE (THEN) L&I SUBCOMMITTEE – NOW OHL SUBCOMMITTEE

• TONY BAKER – VICE PRESIDENT – TECHNOLOGY – K-LINE INSULATORS USA

• AL BERNSTORF – PRINCIPAL ENGINEER – INSULATORS – HUBBELL POWER SYSTEMS

• TOM GRISHAM – CONSULTANT – GRISCUT LTD

• ANDY SCHWALM – PRESIDENT – VICTOR INSULATORS, INC.

WHAT IS AN INSULATOR? WHAT DOES IT DO? AN INSULATOR IS A “DAM***”

POOR CONDUCTOR!

AND MORE, TECHNICALLY SPEAKING!

AN INSULATOR IS A MECHANICAL SUPPORT!

PRIMARY FUNCTION - SUPPORT THE “LINE” MECHANICALLY

SECONDARY FUNCTION– ELECTRICAL

AIR IS THE INSULATOR OUTER SHELLS/SURFACES

ARE DESIGNED TO INCREASE LEAKAGE DISTANCE AND STRIKE DISTANCE

MAINTAINS AN AIR GAP SEPARATES LINE FROM GROUND

LENGTH OF AIR GAP DEPENDS PRIMARILY ON SYSTEM VOLTAGE, MODIFIED BY DESIRED SAFETY MARGIN, CONTAMINATION, ETC.

RESISTS MECHANICAL STRESSES

“EVERYDAY” LOADS, EXTREME LOADS

RESISTS ELECTRICAL STRESSES SYSTEM VOLTAGE/FIELDS,

OVERVOLTAGES RESISTS ENVIRONMENTAL

STRESSES HEAT, COLD, UV,

CONTAMINATION, ETC.

HISTORY• WHERE DID INSULATORS COME FROM?

BASICALLY GREW OUT OF THE NEEDS OF THE TELEGRAPH INDUSTRY – STARTING IN THE LATE 1700S, EARLY 1800S

• HISTORY FROM APPROX. 1840 TO PRESENT GLASS PLATES USED TO INSULATE TELEGRAPH LINE DC TO BALTIMORE

• TYPES OF INSULATORS DISTRIBUTION, TRANSMISSION, SUBSTATION, PORCELAIN, GLASS, NCI, CYCLOALIPHATIC, HDPE ETC.

• COMPARISON OF TYPES (MATERIALS) THE “PLUS AND MINUS” OF THE MULTITUDE OF DESIGNS AND

MATERIALS IN USE TODAY

INSULATOR TYPES - COMPARISONS

• CERAMIC

• PORCELAIN OR TOUGHENED GLASS

• METAL COMPONENTS FIXED WITH CEMENT

• ANSI STANDARDS C29.1

THROUGH C29.10

• NON CERAMIC• TYPICALLY FIBERGLASS

ROD WITH RUBBER (EPDM OR SILICONE) SHEATH AND WEATHER SHEDS

• HDPE LINE INSULATOR APPLICATIONS

• CYCLOALIPHATIC (EPOXIES) STATION APPLICATIONS, SOME LINE APPLICATIONS

• METAL COMPONENTS NORMALLY CRIMPED

• ANSI STANDARDS C29.11 – C29.19

INSULATOR TYPES - COMPARISONS

• CERAMIC

• MATERIALS VERY RESISTANT TO UV, CONTAMINANT DEGRADATION, ELECTRIC FIELD DEGRADATION

• MATERIALS STRONG IN COMPRESSION, WEAKER IN TENSION

• HIGH MODULUS OF ELASTICITY - STIFF

• BRITTLE, REQUIRE MORE CAREFUL HANDLING

• HEAVIER THAN NCIS

• NON CERAMIC• HYDROPHOBIC MATERIALS

IMPROVE CONTAMINATION PERFORMANCE

• STRONG IN TENSION, WEAKER IN COMPRESSION

• DEFLECTION UNDER LOAD CAN BE AN ISSUE

• LIGHTER – EASIER TO HANDLE

• ELECTRIC FIELD STRESSES MUST BE CONSIDERED

INSULATOR TYPES - COMPARISONS

• CERAMIC• GENERALLY DESIGNS ARE

“MATURE”

• LIMITED FLEXIBILITY OF DIMENSIONS

• PROCESS LIMITATIONS ON SIZES AND SHAPES

• APPLICATIONS/HANDLING METHODS GENERALLY WELL UNDERSTOOD

• NON CERAMIC• “MATERIAL PROPERTIES

HAVE BEEN IMPROVED – UV RESISTANCE MUCH IMPROVED FOR EXAMPLE

• STANDARDIZED PRODUCT LINES NOW EXIST

• BALANCING ACT - LEAKAGE DISTANCE/FIELD STRESS – TAKE ADVANTAGE OF HYDROPHOBICITY

• APPLICATION PARAMETERS STILL BEING DEVELOPED

• LINE DESIGN IMPLICATIONS (LIGHTER WEIGHT, IMPROVED SHOCK RESISTANCE)

DESIGN CRITERIA - MECHANICAL• AN INSULATOR IS A MECHANICAL SUPPORT!

ITS PRIMARY FUNCTION IS TO SUPPORT THE LINE MECHANICALLY

ELECTRICAL CHARACTERISTICS ARE AN AFTERTHOUGHT

WILL THE INSULATOR SUPPORT YOUR LINE?

DETERMINE THE MAXIMUM LOAD THE INSULATOR WILL EVER SEE - INCLUDING NESC OVERLOAD FACTORS.

DESIGN CRITERIA - MECHANICAL• LINE POST INSULATORS

• PORCELAIN• CANTILEVER RATING

• REPRESENTS THE AVERAGE ULTIMATE STRENGTH IN CANTILEVER – WHEN NEW.

• MINIMUM ULTIMATE CANTILEVER OF A SINGLE UNIT MAY BE AS LOW AS 85%.

• NEVER EXCEED 40% OF THE CANTILEVER RATING – PROOF TEST LOAD

• NCIS (POLYMER INSULATORS)• S.C.L. (SPECIFIED CANTILEVER LOAD)

• NOT BASED UPON LOT TESTING• BASED UPON MANUFACTURER TESTING

• R.C.L. (REFERENCE CANTILEVER LOAD) OR MDC OR MDCL (MAXIMUM DESIGN CANTILEVER LOAD) OR MCWL OR WCL (WORKING CANTILEVER LOAD)

• NEVER EXCEED RCL OR MDC OR MDCL OR MCWL OR WCL

• S.T.L. (SPECIFIED TENSILE LOAD) • TENSILE PROOF TEST=(STL/2)

DESIGN CRITERIA - MECHANICAL

• SUSPENSION INSULATORS• PORCELAIN

• M&E (MECHANICAL & ELECTRICAL) RATING• REPRESENTS A MECHANICAL TEST OF THE UNIT

WHILE ENERGIZED.• WHEN THE PORCELAIN BEGINS TO CRACK, IT

ELECTRICALLY PUNCTURES.• AVERAGE ULTIMATE STRENGTH WILL EXCEED THE

M&E RATING WHEN NEW.• NEVER EXCEED 50% OF THE M&E RATING

• NCIS (POLYMER INSULATORS)• S.M.L. – SPECIFIED MECHANICAL LOAD

• GUARANTEED MINIMUM ULTIMATE STRENGTH WHEN NEW.

• R.T.L. – ROUTINE TEST LOAD – PROOF TEST APPLIED TO EACH NCI.

• NEVER LOAD BEYOND THE R.T.L.

DESIGN CRITERIA - ELECTRICAL

• DESIGN CRITERIA - ELECTRICAL FOCUS ON THE IMPORTANCE OF STRIKE DISTANCE AS THE PRIMARY CHARACTERISTIC FOR DETERMINING ELECTRICAL PROPERTIES, WITH CONSIDERATION GIVEN TO LEAKAGE (CREEPAGE)

• STRIKE AND LEAKAGE

•DRY 60 HZ F/O AND IMPULSE F/O – BASED ON STRIKE DISTANCE.

•WET 60 HZ F/O - SOME WOULD ARGUE LEAKAGE DISTANCE AS A PRINCIPAL FACTOR. AT THE EXTREMES THAT ARGUMENT FAILS – ALTHOUGH IT DOES PLAY A ROLE.

•LEAKAGE DISTANCE HELPS TO MAINTAIN THE SURFACE RESISTANCE OF THE STRIKE DISTANCE.

DESIGN CRITERIA – ELECTRICALWHAT’S AN APPROPRIATE LEAKAGE

DISTANCE?“Application Guide for Insulators in a Contaminated Environment” by K. C.

Holte et al – F77 639-8

ESDD (mg/cm2)

Site Severity

Leakage Distance

I-string/V-string

(“/kV l-g)

0 – 0.03 Very Light 0.94/0.8

0.03 – 0.06 Light 1.18/0.97

0.06 – 0.1 Moderate 1.34/1.05

>0.1 Heavy 1.59/1.19

IEC 60815 Standards

ESDD (mg/cm2)

Site Severity

Leakage Distance

(“/kV l-g)

<0.01 Very Light 0.87

0.01 – 0.04 Light 1.09

0.04 – 0.15 Medium 1.37

0.15 – 0.40 Heavy 1.70

>0.40 Very Heavy 2.11

DESIGN CRITERIA – ELECTRICAL

WHAT’S AN APPROPRIATE LEAKAGE DISTANCE?

Leakage Distance Recommendations

0

0.5

1

1.5

2

2.5

0 0.1 0.2 0.3 0.4 0.5

ESDD (mg/cm^2)

Lea

k ("

/kV

l-g

)

IEEE V

IEEE I

IEC

Poly. (IEC)

Poly. (IEEE V)

Poly. (IEEE I)

Flashover Vs ESDD

0

50

100

150

200

250

300

0.01 0.1

ESDD (mg/cm^2)

Fla

sh

ov

er

Vo

lta

ge

Porcelain

New EPDM

Aged EPDM

New SR

Aged SR

CEA 280 T 621SR units - leakage equal to porcelainEPDM Units - leakage 1.3 X Porcelain

DESIGN CRITERIA - ELECTRICAL

• IMPULSE WITHSTANDIF ONLY CRITICAL IMPULSE FLASHOVER IS

AVAILABLE – ASSUME 90%

(TAKE POSITIVE OR NEGATIVE POLARITY, WHICHEVER IS LOWER

SAFE ESTIMATE FOR WITHSTAND)

• IMPORTANCE OF CORONA (GRADING) RINGS

INSULATOR ELECTRICAL RATINGS

Dry 60 Hz Flashover Data

0

200

400

600

800

1000

1200

1400

0 20 40 60 80 100 120 140 160

Dry Arcing Distance (inches)

Fla

sh

ov

er (

kV

)

Station Post and Line Post

Suspension Insulator

STANDARDS

• FOCUS ON ANSI STANDARDS

• REVIEW OF MECHANICAL AND ELECTRICAL RATINGS

• ANALYSIS OF RATINGS VS. DESIGN FOR IN SERVICE LOAD REQUIREMENTS

STANDARDSC29 ANSI C29 Insulator Standards (available on-line at nema.org)

.1 Insulator Test Methods

.2 Wet-process Porcelain & Toughened Glass - Suspensions

.3 Wet-process Porcelain Insulators - Spool Type

.4 “ - Strain Type

.5 “ - Low & Medium Voltage Pin Type

.6 “ - High Voltage Pin Type

.7 “ - High Voltage Line Post Type

.8 “ - Apparatus, Cap & Pin Type

.9 “ - Apparatus, Post Type

.10 “ - Indoor Apparatus Type

.11 Composite Insulators – Test Methods

.12 “ - Suspension Type

.13 “ - Distribution Deadend Type

.17 “ - Line Post Type

.18 “ - Distribution Line Post Type

.19 “ - Station Post Type (under development)

STANDARDS• ANSI STANDARDS APPLY TO NEW INSULATORS

AND COVER:

• DEFINITIONS

• MATERIALS

• DIMENSIONS & MARKING (INTERCHANGEABILITY)

• TESTS1.PROTOTYPE & DESIGN, USUALLY PERFORMED ONCE FOR

A GIVEN DESIGN.

(DESIGN, MATERIALS, MANUFACTURING PROCESS, AND TECHNOLOGY).

2.SAMPLE, PERFORMED ON RANDOM SAMPLES FROM LOT OFFERED FOR ACCEPTANCE.

3.ROUTINE, PERFORMED ON EACH INSULATOR TO ELIMINATE DEFECTS FROM LOT.

STANDARDS

STD. No. Insulator Type Sample test Routine test

C 29.2 Ceramic Suspension M&E Tension

C29.3, C29.4

Ceramic Spools and Strains

Tension None

C29.5 Pin Type Puncture Electrical

C29.6 “ Pin Type Cantilever Electrical

C29.7 “ Line Post Cantilever 4 quad. cantilever

C29.8 “ Cap & Pin Cantilever, T, To

Tension

C29.9 “ Station Post Cantilever, T Cantilever, T or BM

C29.10 Indoor Apparatus Cantilever Electrical

C29.12 Composite Suspension SML Tension

C29.13 “ Deadend SML Tension

C29.17 “ Line Post Cantilever, T Tension

C29.18 “ Dist. Line Post Cantilever Tension

STANDARDS – NEW C29.2

C29.2A AND C29.2B

•FOR TRANSMISSION CLASSES (C29.2B) NOW TWO RATINGS CLASS FOR EACH “LEVEL”

•E.G. PREVIOUSLY ONLY CLASS 52-3

•NOW: 52-3L AND 52-3H

STANDARDS – NEW C29.2

ANSI Class

Connection type

Dimensional Values Mechanical Values Electrical ValuesRadio-influence

Voltage Leakag

e distanc

e, inches (mm)

Spacing, inches (mm)

Shell diamete

r, inches (mm)

M&E strengt

h, pounds

(kN)

Impact strengt

h, inch-

pounds (N-m)

Tension proof,

pounds (kN)

Low-frequency dry flashover, kV

Low-frequenc

y wet flashover

, kV

Critical impulse

flashover, positive,

kV

Critical impulse

flashover,

negative, kV

Low-frequenc

y puncture voltage,

kV

Low-frequency test

voltage, kV

Maximum

RIV at 1,000 kHz, µV

52-3-LB&S Type B

11-1/2 (292)

5-3/4 (146)

10-3/4 (273)

15,000 (67)

55 (6.0)7,500 (33.5)

80 50 125 130 110 10 50

52-3-HB&S Type B

11-1/2 (292)

5-3/4 (146)

10-3/4 (273)

20,000 (89)

55 (6.0)10,000 (44.5)

80 50 125 130 110 10 50

52-4-L Clevis11-1/2 (292)

5-3/4 (146)

10-3/4 (273)

15,000 (67)

55 (6.0)7,500 (33.5)

80 50 125 130 110 10 50

52-4-H Clevis11-1/2 (292)

5-3/4 (146)

10-3/4 (273)

20,000 (89)

55 (6.0)10,000 (44.5)

80 50 125 130 110 10 50

52-5-LB&S

Type J11 (279)

5-3/4 (146)

10-3/4 (273)

25,000 (111)

60 (7.0)12,500 (55.5)

80 50 125 130 110 10 50

52-5HB&S

Type J11 (279)

5-3/4 (146)

10-3/4 (273)

30,000 (133)

60 (7.0)15,000 (66.5)

80 50 125 130 110 10 50

52-6-L Clevis11 (279)

5-3/4 (146)

10-3/4 (273)

25,000 (111)

60 (7.0)12,500 (55.5)

80 50 125 130 110 10 50

52-6-H Clevis11 (279)

5-3/4 (146)

10-3/4 (273)

30,000 (133)

60 (7.0)15,000 (66.5)

80 50 125 130 110 10 50

52-8-LB&S Type K

11 (279)

5-3/4 (146)

11-3/4 (298)

36,000 (160)

90 (10)18,000

(80)80 50 125 130 110 10 50

52-8-HB&S Type K

11 (279)

5-3/4 (146)

11-3/4 (298)

40,000 (178)

90 (10)20,000

(89)80 50 125 130 110 10 50

52-10-L Clevis11 (279)

6-1/2 (165)

11-3/4 (298)

36,000 (160)

90 (10)18,000

(80)80 50 125 130 110 10 50

52-10-H Clevis11 (279)

6-1/2 (165)

11-3/4 (298)

40,000 (178)

90 (10)20,000

(89)80 50 125 130 110 10 50

52-11B&S Type K

15 (381)

6-1/8 (155.5)

12-1/4 (311)

50,000 (222)

90 (10)25,000 (111)

80 50 140 140 125 10 50

52-12 Clevis15 (381)

7 (178)

12-1/4 (311)

50,000 (222)

90 (10)25,000 (111)

80 50 140 140 125 10 50

STANDARDS – NEW C29.2

COMBINED MECHANICAL AND ELECTRICAL-STRENGTH TEST

TEN ASSEMBLED INSULATORS SHALL BE SELECTED AT RANDOM FROM THE LOT AND TESTED IN ACCORDANCE WITH 5.2 OF ANSI C29.1. THE CRITERIA FOR DETERMINING CONFORMANCE WITH THE STANDARD ARE AS FOLLOWS:

ALL INSULATORS SUBJECTED TO THE COMBINED MECHANICAL AND ELECTRICAL-STRENGTH TEST SHALL EQUAL OR EXCEED THE RATED COMBINED MECHANICAL AND ELECTRICAL STRENGTHS AS GIVEN IN TABLE 2 OF THIS STANDARD.

STANDARDS – IMPLICATIONS EXAMPLE C29.2 M&E TEST

Coefficient

of variation, vR

Strength value at -3σ

5% 90% of M&E rating

10% 79% of M&E rating

15% 67% of M&E rating

STANDARDS – IMPLICATIONS EXAMPLE C29.7, 8, 9 CANTILEVER TEST

Coefficient

of variation, vR

Strength value at -3 σ

5% 85% of Cantilever rating

10% 70% of Cantilever rating

15% 55% of Cantilever rating

NESC ANSI C2 TABLE 277-1 ALLOWED PERCENTAGES OF STRENGTH RATINGS

Insulator Type % Strength Rating2 Ref. ANSI Std.

Ceramic3

Suspension 50%Combined

mechanical & electrical strength (M&E) C29.2-1992

Line Post40%50%

Cantilever strengthTension/compression

Strength

C29.7-1996

Station Post4

40%50%

Cantilever strengthTension/compression/torsion strength

C29.9-1983

Station Cap & Pin4

40%50%

Cantilever strengthTension/compression/torsion strength

C29.8-1985

Nonceramic5

Suspension 50%Specified mechanical load

(SML)C29.12-1997C29.13-2000

Line Post 50%Specified cantilever load (SCL) or

specified tension load (STL)C29.17-2002C29.18-2003

Station Post 50% All strength ratings ----------

STRENGTHS – MORE IN DEPTH DISCUSSION

2 NEW IEEE PAPERS

•IEEE TF ON INSULATOR LOADING, “HIGH VOLTAGE INSULATORS MECHANICAL LOAD LIMITS –PART I: OVERHEAD LINE LOAD AND STRENGTH REQUIREMENTS,” IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 27, NO. 3, JULY 2012

•IEEE TF ON INSULATOR LOADING, “HIGH VOLTAGE INSULATORS MECHANICAL LOAD LIMITS –PART II: STANDARDS AND RECOMMENDATIONS,” IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 27, NO. 4, OCTOBER 2012.

INSPECTION & EVALUATION – HAVE THE INSULATORS DETERIORATED IN SERVICE?

ANSI C29.2 – 1971 Quality Control(Lot) Tests – M&E Tests

Select random sample from lot: n=10

Determine Average M&E Strength & Standard Deviation s:

Requirements for Average& Standard Deviation: L ≥ M&E Rating + 1.2 s ≤ 1.72 , where = historical standard deviation

Assuming s ≈, the above requirements can be re-stated as

XL = M&E Rating + 1.2 s

Sample Mean

Possible % of M&E Strengths

Less Than Rating = L 11.4 %

If = M&E + 2 s 2.2 %

M&E X L

1.2 š

-1 s

-1 s -2 s

Minimum standard

Typical – good mfg

INSPECTION & EVALUATION – HAVE THE INSULATORS DETERIORATED IN SERVICE?

SOURCES

DOMESTIC MANUFACTURING

• TRANSMISSION PORCELAIN, GLASS – NONE

NCIS- FULL LINES (CHANGING)

• SUBSTATION PORCELAIN – FULL LINES (FOR

NOW)

NCIS- FULL LINES (CHANGING)

• DISTRIBUTION PORCELAIN – ONLY 1 PLANT LEFT

NCIS – FULL LINES

GLASS – NONE

• PORCELAIN: SPOOLS, STRAINS – NONE

CUT OUT PORCELAIN – NONE

LINE POSTS – MIXED

PIN TYPES – 1 PLANT

MARKET SIZE

DATE TOTAL LVPOST HVPOST LVSUSP HV SUSP STATION

SALES SALES SALES SALES SALES SALES

2005 $162,659,854 $9,175,541 $50,689,720 $21,321,445 $37,249,650 $44,223,498

2006 $186,134,838 $8,764,774 $56,879,248 $21,326,689 $42,944,457 $54,341,020

2007 $178,871,136 $8,148,902 $54,370,706 $19,123,333 $41,294,116 $55,934,079

2008 $184,703,067 $9,033,449 $55,328,125 $20,249,198 $45,963,460 $54,128,835

2009 $199,346,541 $7,212,093 $55,796,547 $16,462,470 $64,840,398 $50,381,412

2010 $204,434,456 $5,631,635 $57,686,263 $19,853,611 $57,254,895 $64,008,052

2011 $265,809,282 $8,490,867 $82,247,066 $21,663,012 $78,483,176 $74,925,161

2012 $275,534,244 $8,761,597 $81,904,852 $21,427,918 $91,549,038 $71,890,839

MARKET DISTRIBUTIONS

• DISTRIBUTION – STILL MAINLY PORCELAIN BELOW 35 KV, EXCEPT FOR DEAD ENDS – 90% NCI, GROWING USE OF HDPE

• TRANSMISSION – MAINLY NCI BELOW 345 KV, >50% CERAMIC ABOVE THAT

ECONOMICS

• TRANSMISSION LINES – INSULATORS TYPICALLY <3% TOTAL COST OF LINE

• DISTRIBUTION LINES – INSULATORS TYPICALLY 1% - 3% OF COST OF LINE

INSPECTION & EVALUATION – INSPECTION TECHNIQUES AND EVALUATION OF RESULTS

• VISUAL INSPECTION-• INDIVIDUAL INSULATORS

FROM A BUCKET TRUCK OR HELICOPTER

• BINOCULAR ASSIST

• VIDEO IMAGING-• DAYTIME (DAYCOR)• NIGHT TIME (THERMAL

IMAGING)• EVALUATING CORONA

ACTIVITY• RIV MEASUREMENTS• ESTABLISHED BASIS OF GOOD

AND BAD

• REPLACEMENT OF INSULATORS-• DO NOT “HOT” WORK ANY

LINE WITH KNOWN FAILURES.• PROCEDURES TO WORK “HOT”

LINES IS NO DIFFERENT FOR CERAMIC OR NCI’S.

• UNCERTAIN IF WE SHOULD REPLACE INSULATORS IN THE “HOT” MODE!

• SELECT A RANDOM SAMPLE, N= 30.

• SUBJECT TO M&E TEST AND DETERMINE 30 & S

• WOULD LIKE (3300 – KS) ≥ M&E RATING

• USE STUDENT’S T STATISTIC

• FOR Α = .05 (95% CONFIDENCE), WANT T≥ 1.699.

kk Want Want 30 30 ≥≥

11 M&E + 1.31 sM&E + 1.31 s

22 M&E + 2.31 sM&E + 2.31 s

33 M&E + 3.31 sM&E + 3.31 s