Post on 21-Dec-2015
“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