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Eskom’s unique type test requirements for
Lightning Surge Arrester Ground Lead Disconnectors
Presented at: AMEU Convention 2007
Author & presenter: Rossouw Theron (IARC)
Co-author: Hendri Geldenhuys (IARC)
Industry Association
Resource Centre
By: Rossouw Theron
Date: 15-10-2007
Slide: 1 of 20
Typical surge arrester
Arrester
Arrester
GLD
GLD
Industry Association
Resource Centre
By: Rossouw Theron
Date: 15-10-2007
Slide: 2 of 20
Ground lead disconnector (GLD)
Arrester
Grading
resistor
Spark gap
Spark gap
{
• 22 Blank
cartridge
• 22 Blank
cartridge
Industry Association
Resource Centre
By: Rossouw Theron
Date: 15-10-2007
Grading
resistor
Slide: 3 of 20
Ground lead disconnector (GLD)
Arrester
• 22 Blank
cartridge
Grading
resistor
Spark gap
• 22 Blank
cartridge
Industry Association
Resource Centre
By: Rossouw Theron
Date: 15-10-2007
Slide: 4 of 20
IEC 60099-4: GLD test requirements
IEC 60099-4: Specification for metal-oxide surge arresters
without gaps for a.c. systems
Type test requirements for GLDs according to IEC 60099-4 are:
•Disconnector operation test
•Disconnector withstand tests
Industry Association
Resource Centre
By: Rossouw Theron
Date: 15-10-2007
Slide: 5 of 20
IEC 60099-4: 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
GLD Operating curve
Time in seconds
10
20 A
1
200 A
0.1
800 A
0.01
10
Industry Association
Resource Centre
100
Current in Am pere
By: Rossouw Theron
1000
Date: 15-10-2007
Slide: 6 of 20
IEC 60099-4: 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 test
The arrester and GLD are subjected to a series of
18 long-duration current impulses (2000 μs square wave).
• Operating duty test
The 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: 15-10-2007
Slide: 7 of 20
Field failures
• GLDs that fail to operate
• Premature GLD operation
Industry Association
Resource Centre
By: Rossouw Theron
Date: 15-10-2007
Slide: 8 of 20
Field failures: GLDs that fail to operate
Arresters
failed
GLDs did
not operate
Industry Association
Resource Centre
By: Rossouw Theron
Date: 15-10-2007
Slide: 9 of 20
Field failures: Premature GLD operation
Undamaged
arrester
GLD operated
Industry Association
Resource Centre
By: Rossouw Theron
Date: 15-10-2007
Slide: 10 of 20
Field failures: GLDs that fail to operate
GLD operating curves
100
SEF setting philosophy
• Trip delay: 3 s to 15 s
• Pick-up: 3 A to 6 A
Time in seconds
10
SEF setting
setting range
SEF
range
1
0.1
0.01
1
10
Product A
Industry Association
Resource Centre
By: Rossouw Theron
Current in Ampere
100
Product B
Date: 15-10-2007
1000
Product C
Slide: 11 of 20
Field failures: GLDs that fail to operate
GLD operating curves
100
Specified minimum GLD
operating time:
3s@5A
10
Time in seconds
Typical SEF setting:
5s@5A
SEF setting
setting range
SEF
range
1
0.1
0.01
1
10
Product A
Industry Association
Resource Centre
By: Rossouw Theron
Current in Ampere
100
Product B
Date: 15-10-2007
1000
Product C
Slide: 12 of 20
Field failures: GLDs that fail to operate
New GLD operating curves
100
Time in seconds
10
SEF setting range
1
0.1
0.01
1
10
100
1000
Current in Ampere
Product A
Product B
Product C
Typical SEF setting
Eskom's 5 A, 3 s requirement
Industry Association
Resource Centre
By: Rossouw Theron
Date: 15-10-2007
Slide: 13 of 20
Field failures: Premature GLD operation
GLD current impulse test points according to IEC 60099-4
1000000
Effective duration of typical
lightning current impulses
4/10
8/20
Current [ A ]
100000
10000
1000
0/2000
100
1
10
100
1000
10000
Time [ us ]
Effective duration of impulse (tail time - rise time)
Industry Association
Resource Centre
By: Rossouw Theron
Date: 15-10-2007
Slide: 14 of 20
Field failures: Premature GLD operation
Surge arrester “X”: MOV failure level
1000000
4/10
100000
Effective duration of typical
lightning current impluses
8/20
Current [ A ]
30/80
10000
15/350
1000
0/2000
100
1
10
100
1000
10000
Time [ us ]
Effective duration of impulse (tail time - rise time)
MOV failure level
Industry Association
Resource Centre
By: Rossouw Theron
Date: 15-10-2007
Slide: 15 of 20
Field failures: Premature GLD operation
MOV failure level vs transient operation curve for GLD X
1000000
4/10
100000
Effective duration of typical
lightning current impluses
8/20
Current [ A ]
30/80
10000
15/350
1000
0/2000
100
1
10
100
1000
10000
Time [ us ]
Effective duration of impulse (tail time - rise time)
MOV failure level
Industry Association
Resource Centre
By: Rossouw Theron
GLD X
Date: 15-10-2007
Slide: 16 of 20
Field failures: Premature GLD operation
MOV failure level vs transient operation curves for GLD X & X1
1000000
4/10
100000
Effective duration of typical
lightning current impluses
8/20
Current [ A ]
30/80
10000
15/350
1000
0/2000
100
1
10
100
1000
10000
Time [ us ]
Effective duration of impulse (tail time - rise time)
MOV failure level
Industry Association
Resource Centre
By: Rossouw Theron
GLD X
GLD X1
Date: 15-10-2007
Slide: 17 of 20
Field failures: Premature GLD operation
Benchmarking with 30/80 μs current impulses
40
Ipeak [kA]
30
20
10
0
GLD X
GLD C
GLD B
Withstood
Industry Association
Resource Centre
By: Rossouw Theron
GLD A
GLD X1
Operated
Date: 15-10-2007
Slide: 18 of 20
Eskom’s GLD test requirements
1. Disconnector operation test
GLD operating time is determined at 20 A, 200 A and 800 A, as well as at 5 A / 3 s
2. Long duration current impulse withstand test
18 x 2000 μs square wave current impulses
GLD resistance measurements and 5 A operation verification test
3. Operating duty withstand test
20 x 8/20 μs, 10 kA and 2 x 4/10 μs, 100 kA current impulses
GLD resistance measurements and 5 A operation verification test
4. High lightning duty current impulse withstand test
2 x 30/80, 30 kA current impulses
GLD resistance measurements and 5 A operation verification test
5. Repetitive surge withstand ability test
1000 voltage impulses, sufficient to ensure spark-over of the GLD’s internal gap
GLD resistance measurements and 5 A operation verification test
6. Moisture ingress test
GLD is immersed in boiling water for 42 hours
Industry Association
Resource Centre
By: Rossouw Theron
Date: 15-10-2007
Slide: 19 of 20
QUESTIONS ?
Industry Association
Resource Centre
By: Rossouw Theron
Date: 15-10-2007
Slide: 20 of 20