*

Effect of Barrier on Creeping Discharge along Cylinder Dielectric Surface

NISHI Toshiyuki*

The study of the creeping discharge is very important on the engineering from the viewpoint of the dielectric

breakdown prevention The creeping discharge develops on the dielectric surface when the abnormal voltage like

an inductive lightning surge invades to the equipment inside Creeping discharge can develop on the plane and the

cylinder dielectric surface and it causes the dielectric breakdown phenomenon It is necessary to clarify the

creeping discharge phenomenon in order to prevent the accidents of dielectric breakdown in the equipment

However there are many unsolved points in the characteristics of the creeping discharge The cylinder dielectrics

are used for the coating for wires inside a high voltage equipment like the transformer The creeping discharge

develops along the insulated wire surface inside the high voltage equipment when the inductive lightning surge

invades to one In a high voltage installation it is important to stop the development of creeping discharge in

safety aspect In this paper I report the characteristics of creeping discharge which develops along the cylinder

dielectric surface with the barrier It has been clarified that the blocking effect on the development of positive and

negative creeping discharges

*e-mail:nishi@toyama-nct ac jp

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Fig.1. Experimental circuit.

Fig.2. Shape of barrier.

Fig.3. Shape of high voltage electrode.

. .

Still camera with I.I.

I.I.

I.I. : Image intensifier

I.G.: Impulse voltage generator

h : Height of barrier

d : Distance from electrode to barrier

Meas. ofvoltage

Meas. ofcurrent

Creepingdischarge

Back sideelectrode

High voltage electrode

Vinyl chloridepipe

Barrier

d

r

R

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L

L

a b ,

a

b

Fig.4. Relation between length of creeping discharge and peak value of applied impulse voltage without barrier.

Fig.5. Typical aspects of positive creeping discharge with a barrier.

30 50 60 70 800

60

Peak value of applied impulse voltage m (kV)

De

ve

lop

ing

len

gth

L(c

m)

40

40

20

:Positive creeping discharge

:Negative creeping discharge

2.0

Barrier

High voltage electrode

Vinyl chloride pipe

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a b

a

b

a b

a

b

d=

a b

a

Fig.6. Typical aspects of positive creeping discharge with a barrier.

Fig.7. Typical aspects of positive creeping discharge with a barrier.

b

2.0

Barrier

High voltage electrode

Vinyl chloride pipe

L=20.7cm L=11.0cm

2.0

Barrier

High voltage electrode

Vinyl chloridepipe

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Fig.8. Typical aspects of negative creeping discharge with a barrier.

Fig.9. Typical aspects of negative creeping discharge with a barrier.

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Fig.10. Typical aspects of negative creeping discharge with a barrier.

2.0

BarrierHigh voltage electrode

Vinyl chloridepipe

Fig.10. Typical aspects of negative creeping discharge with a barrier.

2.0

Barrier

High voltage electrode

Vinyl chloride pipe

(a) L=32.1cm (b) L=1.9cm

2.0

Barrier

High voltage electrode

Vinyl chloride pipe

L=23.4cm L=6.0cm

2.0

Barrier

High voltage electrode

Vinyl chloridepipe

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a

b

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(a) Positive creeping discharge.( = kV)

(b) Negative creeping discharge.( = kV)

Fig.12. Relation between development

stopping ratio and distance from

electrode to barrier.

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pp -

M S A A

Hammam

pp -

5.00

60

Distance from electrode to barrier : d(cm)

De

ve

lop

me

nt

sto

pp

ing

ra

tio

(%)

40

20

:h=1.0cm

:h=2.0cm

:h=3.0cm

:h=4.0cm

80

100

10.0 20.015.0 25.0

5.00

60

Distance from electrode to barrier : d(cm)

De

ve

lop

me

nt

sto

pp

ing

ra

tio

(%)

40

20

:h=1.0cm

:h=2.0cm

:h=3.0cm

:h=4.0cm

80

100

10.0 20.015.0 25.0

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pp -

pp -

pp -

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