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Quantitative analysis of gas circuit breaker physics through direct comparison of 3D simulations with experiment

N.P.Basse, M.Abrahamsson, M.Seeger and T.Votteler

2007 IEEE Pulsed Power andPlasma Science Conference

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Introduction

We study interruption of short-circuit current in high-voltage gas circuit breakers

Pressure produced by the arc is used to extinguish the arc, i.e. the self-blast principle

We measure the pressure buildup using two spatially separated sensors

The pressure and other measured quantities are compared to a 3D computational fluid dynamics (CFD) simulation

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CFD simulation setup

Left-hand plot shows the grid used for the CFD simulation A 180 degree cut is simulated

No turbulence is included

Right-hand plot shows the heating volume and the positions where pressure is simulated Position 3 is the

actual sensor location

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CFD pressure animation

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Current interruption phases

Sequence of events

1. Ablation controlled arc, backheating from arc zone to heating volume

2. Flow reversal when the heating volume pressure equals the arc pressure

3. Axially blown arc, flow from heating volume to arc zone

4. Arc extinction Plot above shows pressure

monitor points in the 3D simulation Here, we analyze results from

position 1 and 21

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Heating volume pressure and arc parameters

Left: Heating volume pressure

Right: Arc current and voltage

-0.02 -0.01 0 0.01 0.020

5

10

15

20

25

30

Time [s]

Pre

ssu

re [b

ar]

Measurement3D simulation

-0.02 -0.01 0 0.01 0.02-70

-35

0

35

70

Cu

rre

nt [

kA]

Time [s]-0.02 -0.01 0 0.01 0.02

-600

-300

0

300

600

Arc

vo

ltag

e [V

]

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Transient between flow reversal and CZ

A pressure transient a few ms before current zero (CZ) has been identified using cross correlation analysis

The oscillation is between the arc zone and the heating volume

Time [s]

Tim

ela

g [s

]

Cross correlation (hv1 and hv2)

-0.02 -0.01 0 0.01 0.02

-1.5

-1

-0.5

0

0.5

1

1.5

x 10-3

-1

-0.5

0

0.5

1

Time [s]

Tim

ela

g [s

]

Cross correlation (p1 and p21)

-0.02 -0.01 0 0.01 0.02

-1.5

-1

-0.5

0

0.5

1

1.5

x 10-3

-1

-0.5

0

0.5

1

Left simulations, right measurements

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Early transient in heating volume

Below we show auto correlation functions for both pressure measurements

An oscillation is observed at -0.01 s with a period of about 1.7 ms at one sensor position (left-hand plot)

Time [s]

Tim

ela

g [s

]

Auto correlation hv1

-0.02 -0.01 0 0.01 0.02

-1.5

-1

-0.5

0

0.5

1

1.5

x 10-3

-1

-0.5

0

0.5

1

Time [s]

Tim

ela

g [s

]

Auto correlation hv2

-0.02 -0.01 0 0.01 0.02

-1.5

-1

-0.5

0

0.5

1

1.5

x 10-3

-1

-0.5

0

0.5

1

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Pressure mixing

The pressure ratio 180 degrees apart is used to gauge the uniformity of pressure

Simulation (measurement) up to 1% (25%) difference, respectively

-0.02 -0.01 0 0.01 0.020.7

0.8

0.9

1

1.1

1.2

Time [s]

Pre

ssu

re r

atio

[hv2

/hv1

]

-0.02 -0.01 0 0.01 0.020.99

0.995

1

1.005

1.01

Time [s]

Pre

ssu

re r

atio

[p2

1/p

1]

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Temperature

Left: Temperature at sensor positions is very different after flow reversal Average heating volume temperature reflects current behavior

Right: With the sound speed of SF6 and dimensions of the circuit breaker, cross correlation periods can be used to derive average temperatures

-0.02 -0.01 0 0.01 0.020

500

1000

1500

2000

2500

Time [s]

Te

mp

era

ture

[K]

Averagep1p21

500 1000 1500 2000 2500 30000

200

400

600

800

1000

1200

Temperature [K]

SF

6 so

un

d s

pe

ed

[m/s

]

1 bar25 bar

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Pressure in arc zone and heating volume

Left: Simulated heating volume and arc zone pressure

Right: Cross correlation of the pressures

-0.02 -0.01 0 0.01 0.020

5

10

15

20

25

Time [s]

Pre

ssu

re [b

ar]

p1Stagnation point

Time [s]

Tim

ela

g [s

]

Cross correlation (p1 and psp

)

-0.02 -0.01 0 0.01 0.02

-1.5

-1

-0.5

0

0.5

1

1.5

x 10-3

-1

-0.5

0

0.5

1

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Pressure fluctuations

Power spectra of the two pressure measurements integrated up to 20 kHz are shown below

Most fluctuations during the final rise of the pressure

-0.02 -0.01 0 0.01 0.020

5

10

15

20

25

30

35

40

Time [s]

Pressure [bar]Fluctuations [a.u.]

-0.02 -0.01 0 0.01 0.020

5

10

15

20

25

30

35

40

Time [s]

Pressure [bar]Fluctuations [a.u.]