Fluke 540B - Page 19

540B
STEP
CONTROL
POSITION
OPERATION
a
POWER
ON
Set the RANGE switch to succeedingly lower volt-
GALV
OPEN
age ranges un til an indication between 50% and 100%
SENSITIVITY
LOW
is obtained
on the PERCENT INPUT meter. (Better
RANGE 1000v
transfer resolution is obtained with readings closer
M OD E
AC SEARCH
to 100% .)
b
SENSITIVITY
LOW
T ap the GAL V switch against th e spring tension to
MODE
AC TRANSFER
MOMENTARY just long enough to see if the GAL-
GALV
V ANOMETER
needle will stay on scale. Adjust
REFERENCE
COARSE
th e COARSE and MEDIUM controls until a zero
ADJUST MED IUM
reading is obtained.
c
GALV
OP EN
Adjust
the GALV ZERO cont r ol for zero reading on
SENSITIVITY
ME D
the GALVANOMETER.
GALV
ZERO
d GALV
LOCK
Adjust the MEDIUM and FINE controls for zero
REFERENCE
MED IUM
reading on the GALVANOMETER.
ADJUST
FINE
e
GALV
OP EN
Adj
ust the GALV ZERO control for zero reading on
SENSITIVITY HIGH
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
DC SEARCH
A
djust th e de source voltage until a reading is
obtained on the P E RCENT INPUT meter t ha t is
equal to the reading noted in step a.
i MODE
DC TRANSFER
NOTE: DO NOT ADJUST
THE REFERENCE AD-
JUST CONTROLS IN THIS MODE.
j
SENSITIVITY
LOW
Tap the GAL V switch against the s pring tension to
GALV
MOMENTARY
just long enough to see if the GAL-
V AN OMETER needle will s tay on s cale. Adjust
the de source voltage until ze r o is obtained.
k GALV
LOCK
Further refine the adjustmen t of the de source volt-
SENSITIVITY
MEDIUM
age until zero reading on t he GALVANOMETER is
HIGH
obtained in the HIGH SENSITIVITY position.
l
Recor d th e exact de sourc e voltage.
m
R epeat steps b through l at l east three times or until repeatibility is attained.
R ecord the exact
de voltage .
n
Reverse the input polar i ty to the thermocou ple by depressing the POLARITY switch.
Repeat
steps b through l at least three times or until repeatibility is atta ined.
Record the exact de voltage .
0
The rms value of the unknown ac voltage is equal to the average of the two de voltages recorded in
steps 1 and n.
NOTE:
If a tes t report from a standards laboratory is used ,
calculate the unknown ac voltage from the
following equation:
Eac =(1 +ao Edc
100
Where:
Edc
=
average of two de voltages recorded
ao
=
Eac - Edc
100 =
ac to de percent difference from
Edc
the test report
Figure 2- 6. MEAS URING AN UNKNOWN AC VOLTAGE
2-7