Fluke 540B - Page 24

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540B

STEP

CONTROL

POSITION OPERATION

a RANGE

SH

UNT

Set

the

OUTPUT MODE

switch

to DC,

if

using

the

POWER

ON

A45

Transfer

swi

tch.

Adjust

the

de

source

until

SE

NS

ITIVITY LOW

the

de

current

exactl

y

equals

the

rms

value

of

the

MODE

OFF

ac

current

to

be

calibrat

ed.

Tap

the

GAL V switch

GALV

against

the

spring

t

ensio

n to MOMENTARY

just

REFERENCE

COARSE long enough

to

see

if

the

GALVANOMETER

needle

ADJUST MEDIUM

will

stay

on

scale.

Adjust

the

COARSE AND

MEDIUM REFERENCE ADJUST

control

s

until

a

zero

reading

is

obtained.

b

GALV OPEN

Adjust

the

GALV

ZERO

control

for

zero

reading

SENSITIVITY MED on

the

GALVANOMETER.

GALV

ZERO

c GALV LOC K

Adju

st

the

MEDIUM

and

FINE

control

s

for

a

zero

REF

EREN

CE

MEDIUM

reading

on t he GALVANOMETER.

ADJUST F

IN

E

d GALV

OPEN Adjust

the

GALV Z

ERO

control

for

zero

reading

SENSITIVITY

HIGH on

the

GALVANOMETER.

GALV

ZERO

e

GALV

LOCK

Adjust

the

FlNE

control

f

or

a

ze

r o

reading

on

the

REFERENCE

GALVANOMETER.

ADJUST

FINE

f GALV

OPEN

Disconnect

the de s

ource

f

ro

m

the

shunt

an

d

SENSIT

IV

I

TY

LOW

connect

the

ac

to

be

calibrated

to

it.

If

using

the

A45

Tran

s

fer

Switch

set

the

OUTPUT MODE

switch

to

AC.

g GALV

Tap

the

GALV s

witch

against

the

spring

tension

to

MOMENTARY

just

long enough

to

see

if

t he

GALVANOMETER

needle

w

ill

stay

on

scale

while

adjusting

the

level

of

the

ac

to

be

calibrated.

Re-

peat

until

a

zero

reading

is

obtained

. Do n

ot

ad -

just

the

REFERENCE

ADJUST

controls

in t

his

mode.

h

GALV

LOCK

Further

refine

the

level

adjus

t

ment

of

the

ac

to

be

SENSIT

IV

IT

Y MED

calibrat

ed

for

a

zero

reading

on

the

GALV ANO-

HIG

H

METER

in

the

MED

and

HIGH

sensitivity

posi

tions.

1 GALV OPEN

Disconnect

the

ac

being

calibrated

and

reconnect

the

de

source.

If

using

the

A45

Tra

n

sfer

Switch,

set

the

OUTP

UT MODE s wi

tch

to

DC.

j GALV

LOCK

Readjust

th

e FINE

REFERE

N

CE

control

for

ze

ro

re

adin

g on

th

e GALVANOMETER.

k GALV OPEN

Disconnect

the

de

sourc

e

from

the

shunt

inp

ut

an

d

reconnect

the

ac

to

be

calir>rated.

If

using

t he A45

T

ransfer

Switch,

set

the

OUTPUT

MODE

s

wit

ch

to

AC.

1 GALV LOCK Adjust

the

ac

curren

t to be

calibrated

to

maint

a in

zero

on

the

GALVANOMETER.

Record

ac

cur -

rent

source

se

tting.

m

Repeat

steps

i

through

l

at

least

three

times

or

un

til

repeatibility

is

at

tained.

Record

the

ac

current

source

setting.

n

Reverse

the

input

polarity

to

the

thermocouple

by

depressing

the

POLARITY

switc

h.

Repea

t

steps

i

through

l

at

least

three

times

or

until

repeatibility

is

attained.

Record

th

e

ac

curre

nt

source

setting.

0

Set

th

e

ac

current

source

adjustment

in

the

cent

er of

the

two

settings

recorded

in

steps

m

and

n.

The

rm

s

value

of the ac

curren

t now

equals

that

desired.

Figure

2-

1

0,

CALI

BRATI

NG

AN

AC

CU

RRENT

SOURCE

2-12

r-

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