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Line Arresters: Evaluating Flashover Performance and
Discharge Duty
T. E. McDermott
Univ. of Pittsburgh
1-412-648-9585
1
mailto:[email protected]
Two open-source software programs with spreadsheet interfaces estimate line performance with arresters.
2
http://sourceforge.net/projects/epri-openetran/
GPL v3
License
http://sourceforge.net/projects/ieeeflash/
BSD
License
IEEE Flash “Classic” focused on shielding and grounding; no arrester models.
3
OpenEtran simulates traveling wave effects on line segments, insulators, grounds, surge arresters and lightning surges.
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M InsulatorArrester
Span 2 Span 3 Span 4Span 1
Pole 1 Pole 2 Pole 3 Pole 4 Pole 5
TerminationUngrounded Pole
Surge Current
Termination
DC BiasDC Bias
Arresters have nonlinear and frequency-dependent discharge characteristics.
5
OpenEtran waveforms show the effects of line arresters (at every other pole) on the insulator voltages.
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-4.0E+05
-3.5E+05
-3.0E+05
-2.5E+05
-2.0E+05
-1.5E+05
-1.0E+05
-5.0E+04
0.0E+00
5.0E+04
0.0E+00 5.0E-06 1.0E-05 1.5E-05 2.0E-05 2.5E-05
Vo
ltag
e [
V]
Time [s]
P16 ph A P17 ph A P17 ph B
-4.0E+05
-3.5E+05
-3.0E+05
-2.5E+05
-2.0E+05
-1.5E+05
-1.0E+05
-5.0E+04
0.0E+00
5.0E+04
0.0E+00 5.0E-06 1.0E-05 1.5E-05 2.0E-05 2.5E-05
Vo
ltag
e [
V]
Time [s]
P16 ph A P17 ph A P17 ph B
54-kA Stroke
No Flashover
55-kA Stroke
Causes Flashover
IEEE Flash calls OpenEtran with a root-finding method to find critical stroke current causing flashover.
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5max max( ) 1 ( ) 10flashoverF I SI T t
-4.0E+05
-3.5E+05
-3.0E+05
-2.5E+05
-2.0E+05
-1.5E+05
-1.0E+05
-5.0E+04
0.0E+00
5.0E+04
0.0E+00 5.0E-06 1.0E-05 1.5E-05 2.0E-05 2.5E-05
Vo
ltag
e [
V]
Time [s]
P16 ph A P17 ph A P17 ph B
-4.0E+05
-3.5E+05
-3.0E+05
-2.5E+05
-2.0E+05
-1.5E+05
-1.0E+05
-5.0E+04
0.0E+00
5.0E+04
0.0E+00 5.0E-06 1.0E-05 1.5E-05 2.0E-05 2.5E-05
Vo
ltag
e [
V]
Time [s]
P16 ph A P17 ph A P17 ph B
I = 54 kA; SImax = 0.99
Almost a flashover
I = 55 kA; SImax = 1.00
Flashover did occur
This function of peak stroke current, I, is zero when a
flashover just barely occurred somewhere on the line.
This lightly-weighted
term is zero when
flashover occurred
right at the end of
the simulation.
For a stroke to shield wire, most of the stroke current goes directly into the tower footing resistance.
8
For a stroke to tower, line arresters prevent insulator flashover with little energy or charge duty.
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-1.2E+05
-1.0E+05
-8.0E+04
-6.0E+04
-4.0E+04
-2.0E+04
0.0E+00
0.0E+00 5.0E-06 1.0E-05 1.5E-05 2.0E-05 2.5E-05
Cu
rre
nt
[A]
Time [s]
T11 grnd
0.0E+00
1.0E+05
2.0E+05
3.0E+05
4.0E+05
5.0E+05
0.0E+00 5.0E-06 1.0E-05 1.5E-05 2.0E-05 2.5E-05
Vo
ltag
e [
V]
Time [s]
T11 ph A T11 ph B T11 ph C
0.0E+00
2.0E+02
4.0E+02
6.0E+02
8.0E+02
1.0E+03
1.2E+03
1.4E+03
0.0E+00 5.0E-06 1.0E-05 1.5E-05 2.0E-05 2.5E-05
Curr
ent [
A]
Time [s]
T11 ph A T11 ph B T11 ph C
Tower ground current
Insulator voltages
Arrester currents
For a stroke to phase conductor, the arrester energy and charge duty is much higher.
10
Arresters also share the current discharge for a stroke to the phase conductor on a distribution line.
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0
5
1 0
1 5
2 0
2 5
3 0
3 5
0 2 5 5 0 7 5 1 0 0 1 2 5 1 5 0 1 7 5 2 0 0
A r r e s t e r a n d S t r o k e C u r r e n t s - U n d e r b u i l t G r o u n d W i r e
Cu
rr
en
t
(k
A)
T im e (u s )
L e ft M id d le S tro k e
Microsoft Excel provides the user interface, running simulations through Visual Basic for Applications (VBA)
12
Critical currents for two 230-kV lines; results are used to check for acceptable tower ground resistances.
13
IEEE Flash checks Lightning Detection Network events to identify lines with possible design issues (black dots).
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0 2 4 6 8 10 12 14 16 18 200
20
40
60
80
100
120
140
160
180
200
Event #
Peak C
urr
ent |k
A|
BackFlash
Shield
For a stroke to shield wire, the arrester duty is higher but nearby arresters will share much of the duty.
15
0
0.5
1
1.5
2
2.5
3
0 50 100 150 200
Arr
est
er
Ch
arge
[C
]
Stroke Current [kA]
Ph Charge [C] 65 kA 4x10 100 kA 4x10
SL 5 kA SI 10 kA SH 20 kA
Want to help with OpenEtran? Try improving the model of induced voltages from nearby strokes.
16
037.3
4.7
eff
m
eff
hU I CFO
y
h h
IEEE Std. 1410-2010 (Rusck / Darveniza)
Proposed New Model: Høidalen, “Calculation of Lightning-induced
Voltages in MODELS Including Lossy
Ground Effects”, [Online] at www.ipst.org
Want to help with IEEE Flash? Try implementing the CFO-added method, or transmission counterpoise.
17