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Industry Association Resource Centre By: Rossouw Theron Date: 28-05-2007 Slide: 1 of 18
IEC’s test requirements for Ground Lead Disconnectors,
not sufficient for Eskom applications
Presented at: UPDEA Colloquium Electrotechnical Standardisation
Presented by: Rossouw Theron (IARC)
Industry Association Resource Centre By: Rossouw Theron Date: 28-05-2007 Slide: 2 of 18
Arrester
Arrester
GLD
GLD
Typical surge arresterTypical surge arrester
Industry Association Resource Centre By: Rossouw Theron Date: 28-05-2007 Slide: 3 of 18
Arrester
Grading resistor
Grading resistor
Spark gapSpark gap {
Ground lead disconnector (GLD)Ground lead disconnector (GLD)
Industry Association Resource Centre By: Rossouw Theron Date: 28-05-2007 Slide: 4 of 18
Spark gap Grading resistor
Arrester
• 2 Cartridge
• 2 Cartridge
Ground lead disconnector (GLD)Ground lead disconnector (GLD)
Industry Association Resource Centre By: Rossouw Theron Date: 28-05-2007 Slide: 5 of 18
IEC 60099IEC 60099--4: GLD test requirements4: GLD test requirements
IEC 60099-4: Specification for metal-oxide surge arresters without gaps for a.c. systems
Type test requirments for GLDs according to IEC 60099-4 are:•Disconnector withstand tests•Disconnector operation test
Industry Association Resource Centre By: Rossouw Theron Date: 28-05-2007 Slide: 6 of 18
IEC 60099IEC 60099--4: GLD test requirements4: GLD test requirements
Disconnector withstand tests:When an arrester is fitted with a GLD it shall withstand, without operating, each of the following tests:
• Long-duration current impulse testThe arrester and GLD are subjected to a series of 18 long-duration current impulses (2000 μs square wave).
• Operating duty testThe arrester and GLD is subjected to a series of 20 lightning current impulses (10 kA, 8/20 μs) and 2 high current impulses (100 kA, 4/10 μs).
Industry Association Resource Centre By: Rossouw Theron Date: 28-05-2007 Slide: 7 of 18
IEC 60099IEC 60099--4: GLD test requirements4: GLD test requirements
Disconnector operation test:The time delay for the operation of the disconnector is determined for three values of current, 20 A, 200 A and 800 A r.m.s
GLD operation curve
0.01
0.1
1
10
10 100 1000Current in Ampere
Tim
e in
sec
onds 20 A
200 A
800 A
Industry Association Resource Centre By: Rossouw Theron Date: 28-05-2007 Slide: 8 of 18
Failures Failures –– Prior to 2003Prior to 2003
Arresters failed
GLDs did not operate
Industry Association Resource Centre By: Rossouw Theron Date: 28-05-2007 Slide: 9 of 18
SEF setting philosophy• Trip delay: 3 s to 15 s• Pick-up: 3 A to 6 A
0.01
0.1
1
10
100
1 10 100 1000Current in Ampere
Tim
e in
sec
onds
Grading of Sensitive Earth Fault (SEF) with GLDGrading of Sensitive Earth Fault (SEF) with GLD
Typical GLD operation curves
Industry Association Resource Centre By: Rossouw Theron Date: 28-05-2007 Slide: 10 of 18
Typical SEF setting:5 s @ 5 A
Specified minimum GLD operating time:
3 s @ 5 A
0.01
0.1
1
10
100
1 10 100 1000Current in Ampere
Tim
e in
sec
onds
Specified GLD operating timeSpecified GLD operating time
Industry Association Resource Centre By: Rossouw Theron Date: 28-05-2007 Slide: 11 of 18
Failures: 2004 Failures: 2004 -- 20052005
GLD operated
Arrester not damaged
Industry Association Resource Centre By: Rossouw Theron Date: 28-05-2007 Slide: 12 of 18
100
1000
10000
100000
1000000
1 10 100 1000 10000
Time [ us ] Effective duration of impulse (tail time - rise time)
Cur
rent
[ A
]
Typical
lightning
flash current
duration
8/204/10
0/2000
GLD test points according to IEC 60099GLD test points according to IEC 60099--44
Industry Association Resource Centre By: Rossouw Theron Date: 28-05-2007 Slide: 13 of 18
100
1000
10000
100000
1000000
1 10 100 1000 10000Time [ us ]
Effective duration of impulse (tail time - rise time)
Cur
rent
[ A
]
MOV failure level
Typical
lightning
flash current
duration
8/204/10
0/2000
30/80
Arrester damage curveArrester damage curve
Industry Association Resource Centre By: Rossouw Theron Date: 28-05-2007 Slide: 14 of 18
100
1000
10000
100000
1000000
1 10 100 1000 10000Time [ us ]
Effective duration of impulse (tail time - rise time)
Cur
rent
[ A
]
MOV failure level Old GLD
Typical
lightning
flash current
duration
8/204/10
0/2000
30/80
Arrester damage curve vs transient operation curve of GLDArrester damage curve vs transient operation curve of GLD
Industry Association Resource Centre By: Rossouw Theron Date: 28-05-2007 Slide: 15 of 18
100
1000
10000
100000
1000000
1 10 100 1000 10000Time [ us ]
Effective duration of impulse (tail time - rise time)
Cur
rent
[ A
]
MOV failure level Old GLD New GLD
Typical
lightning
flash current
duration
8/204/10
0/2000
30/80
Arrester damage curve vs transient operation curve of GLDArrester damage curve vs transient operation curve of GLD
Industry Association Resource Centre By: Rossouw Theron Date: 28-05-2007 Slide: 16 of 18
GLD operation for 30/80 us current impulseGLD operation for 30/80 us current impulse
0
10
20
30
40
Product X (Old) Product A Product B Product C Product X (New )
Ipea
k [k
A]
Withstood Operated
Industry Association Resource Centre By: Rossouw Theron Date: 28-05-2007 Slide: 17 of 18
Eskom’s GLD test requirementsEskom’s GLD test requirements
1. Disconnector operation testGLD operating time is determined at 20 A, 200 A and 800 A, as well as at 5 A
2. Long duration current impulse withstand test18 x 2000 μs square wave current impulsesGLD resistance measurements and 5 A operation test
3. Operating duty withstand test20 x 8/20 μs, 10 kA and 2 x 4/10 μs, 100 kA current impulsesGLD resistance measurements and 5 A operation test
4. High lightning duty current impulse withstand test2 x 30/80, 30 kA current impulsesGLD resistance measurements and 5 A operation test
5. Repetitive surge withstand ability test1000 voltage impulses, sufficient to ensure spark-over of the GLD’s internal gap GLD resistance measurements and 5 A operation test
6. Moisture ingress testGLD is immersed in boiling water for 42 hours
Industry Association Resource Centre By: Rossouw Theron Date: 28-05-2007 Slide: 18 of 18
QUESTIONS ?