Biddle MEGGER - Page 23

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10.

Outdoor

Oil

Circuit

Breakers

The

four

illustrations

(Figs.

23,

24,

25

and

26)

show

the

usual

methods

of

testing

bushings

and

associated

parts

of

an

outdoor

oil

circuit

breaker,

and

the

accompanying

table

indi-

cates

the

test

procedure

by

steps.

If

the

test

values

are

below

10,000

megohms

in

any

of

the

4

steps,

the

tank

should

be

lowered

or

drained

so

that

the

ex-

cessive

losses

can

be

isolated

by

further

tests

and

investigations.

If

the

test

values

are

below

50,000

megohms

in

test

#1,

the

trend

of

the

condition

of

the

particular

bushing

involved

should

be

watched

by

making

more

frequent

tests.

See

page

44.

Test

Breaker

Bushing

Bushing

Bushing

Part

Position

|

Energized

Guarded

|

Grounded

Measured

1

open

1

(2

to

TT

Pe

hams

air

setts

Bushing

1

guard)

2

open

1

1

2

Bushing

1

in

parallel

with

cross

member

3

open

κο

ο

ος.

Bushing

1

&

2

in

parallel

4

closed

Tee?

ο

ο

τος,

Bushing

1

&

2

in

parallel

with

lift

rod

BUSHING

N°2

BUSHING

N°]

"MEGGER"

INSULATION

TESTER

FIGURE

23.

Step

1.

[21]