Line Arresters: Evaluating Flashover Performance and

Discharge Duty

T. E. McDermott

Univ. of Pittsburgh

tem42@pitt.edu

1-412-648-9585

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mailto:tem42@pitt.edu

Two open-source software programs with spreadsheet interfaces estimate line performance with arresters.

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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.

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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.

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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.

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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.

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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)

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Critical currents for two 230-kV lines; results are used to check for acceptable tower ground resistances.

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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.

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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.

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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.

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