Biddle MEGGER - Page 39

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Where

the

resistance

of

the

circuit

under

test

is

high,

i.e.,

above

the

middle

of

the

scale

of

instrument

being

used,

approx-

imately

full

rated

voltage

will

be

obtained

when

using

the

<

Earth

and

Line

connections.

In

this

case

no

dangerous

over-

_

load

will

occur

under

any

conditions

because

of

the

protective

ballast

resistance

within

the

instrument.

See

Figure

45.

NOTE:

Heavy-Duty

Megger

Insulation

Testers

supplied

after

Septem-

ber

1969

DO

NOT

HAVE

a

guard

circuit

for

protective

resist-

ance.

If

the

instrument

is

ever

used

for

Dielectric

Strength

or

Breakdown

tests

by

using

the

Earth

and

Guard

terminals

—a

protective

resistance

of

40,000

ohms

should

be

con-

nected

externally

in

series

with

the

guard

terminal.

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