Biddle MEGGER - Page 12

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PREPARATION

OF

APPARATUS

FOR

TEST

1.

Take

Out

of

Service

Shut

down

the

apparatus.

Open

switches.

De-energize.

Dis-

connect

from

other

equipment

and

circuits,

including

neu-

tral

and

protective

(workmen’s

temporary)

ground

connections.

See

Safety

Precautions,

page

11.

2.

Make

Sure

Just

What

Is

Included

in

the

Test

Inspect

the

installation

very

carefully

to

determine

just

what

equipment

is

connected

and

will

be

included

in

the

test,

espe-

cially

if

it

is

difficult

or

expensive

to

disconnect

associated

apparatus

and

circuits.

Pay

particular

attention

to

conductors

that

lead

away

from

the

installation.

This

is

very

important,

because

the

more

equipment

that

is

included

in

a

test,

the

lower

the

reading

will

be,

and

the

true

insulation

resistance

of

the

apparatus

in

question

may

be

masked

by

that

of

the

associated

equipment.

It

is

always

possible,

of

course,

that

the

insulation

resistance

of

the

complete

installation

(without

disconnecting

every-

thing)

will

be

satisfactorily

high,

especially

for

a

spot

check.

Or,

it

may

be

higher

than

the

range

of

the

“Megger”

instrument

in

use,

in

which

case

nothing

would

be

gained

by

separating

the

components,

because

the

insulation

resistance

of

each

part

would

be

still

higher.

For

an

initial

test,

it

may

be

necessary

to

separate

the

com-

ponent

parts,

even

though

labor

and

expense

are

involved,

and

test

each

one

separately.

Also

make

a

test

of

all

the

components

connected

together.

With

this

information

on

record,

it

may

not

be

necessary

to

separate

the

components

on

future

tests

unless

unaccountably

low

readings

are

observed.

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