Fluke 540B - Calibrating an AC Voltage Source

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540B

STEP

CONTROL

POSITION

OPERATION

a

POWER

ON

Set

the

RANGE

switch

in a

position

that

will

cause

GALV

OPEN

the

PERCENT

INPUT

meter

to

indicate

close

to,

SENSITIVITY LOW

but

not

exceed,

100%

for

the

level

to

be

calibrated.

RANGE

Adjust

the

de

source

voltage

to

the

exact

rms

value

MODE

DC SEARCH

of

the

ac

voltage

to

be

calibrated.

(Note

PERCENT

INPUT

meter

indication.

)

b MODE

DC

TRANSFER

Tap

the

GALV

switch

against

the

spring

tension

to

GALV

MOMENTARY

just

long enough

to

see

if

the

GAL-

REFERENCE

COARSE

VANOMETER

needle

will

stay

on

scale

.

Adjust

ADJUST

MEDIUM

the

COARSE

and

MEDIUM

controls

until

a

zero

reading

is

obtained.

c GALV

OPEN

Adjust

the

GALV

ZERO

control

for

zero

reading

SENSITIVITY MED

on

the

GALVANOMETER.

GALV

ZERO

d

GALV

LOCK

Adjust

the

MEDIUM

and

FINE

controls

for

zero

REFERENCE

MEDIUM

reading

on

the

GALVANOMETER.

ADJUST

FINE

e

GALV

OPEN

Adjust

the

GALV

ZERO

control

for

a

zero

reading

SENSITIVITY HIGH.

on

the

GALVANOMETER.

GALV

ZERO

--

f GALV

LOCK

Adjust

the

FINE

control

for

a

zero

reading

on

the

REFERENCE

GALVANOMETER.

ADJUST FINE

g GALV

OPEN

SENSITIVITY

LOW

h MODE

AC SEARCH

Adjust

the

ac

level

to

be

calibrated

until

a

reading

is

obtained

on

the

PERCENT

INPUT

meter

that

is

equal

to

the

reading

obtained

and

noted in

step

a.

i

MODE

AC

TRANSFER

NOTE: DO NOT ADJUST

THE

REFERENCE

ADJUST CONTROLS IN THIS MODE.

j

SENSITIVITY

LOW

Tap

the

GALV

switch

against

the

spring

tension

to

GALV

MOMENTARY

just

long enough

to

see

if

the

GAL-

VANOMETER

needle

will

stay

on

scale

while

adjust-

ing

the

level

of

the

ac

to

be

calibrated.

When

an

on

scale

reading

is

obtained

adjust

the

ac

level

for

a

zero

reading

on

the

GALVANOMETER.

k GALV

LOCK

Further

refine

the

adjustment

of

the

ac

voltage

until

SENSITIVITY

MED a GALVANOMETER

reading

of

zero

is

obtained

in

HIGH

the

MED

and

HIGH

SENSITIVITY

positions.

Record

the

ac

voltage

source

setting.

1

Repeat

steps

b

through

k

at

least

three

times

or

until

repeatibility

is

attained.

Make

note

of

the

ac

source

setting.

m

Reverse

the

input

polarity

to

the

thermocouple

by

depressing

the

POLARITY

switch.

Repeat

steps

b

through

k

at

l

east

three

times

or

until

repeatibility

is

attained.

Make

note

of

the

ac

source

setting.

n

Set

the

ac

source

voltage

adjustment

in

the

center

of

the

two

settings

recorded

in

steps

l

and

m.

The

rms

value

of

the

ac

voltage

now

equals

that

desired.

Figure 2- 7. CALIBRATING

AN

AC VOLTAGE

SOURCE

2-9

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