(3) Set the GALV switch to OPEN.
Depress the POLARITY switch until it
locks and remains in the depressed position.
Wait approximately 5 seconds; then
place the GALV switch in the LOCK position.
(4) The resulting GALVANOMETER deflection indicates the amount of DC
reversal error. The percent change may be computed by multiplying the deflection
sensitivity determined in step (a) by the amount of DC reversal error.
(5) Set the GALV switch to OPEN.
Set the POLARITY switch to its normal
(up) position.
g. Throughout the following AC voltage measurement
procedure, refer back to
Figure 2-3 as necessary to ensure your understanding of
the operating procedure.
Before connecting and energizing the Model 540B, always
set the RANGE switch to
1000, MODE switch to OFF, and make sure the GALV switch
is in the OPEN position.
Perform the battery check as described in para 10.
(1) Set the SENSITIVITY switch to MEDIUM, POWER switch to ON and adjust the
GALV zero control for zero on the galvanometer after sufficient warmup time.
(2) Connect the unknown AC voltage to the AC INPUT terminal(s).
Set the
MODE switch to AC SEARCH and down range the RANGE switch slowly until the PERCENT
INPUT meter has an indication in the green area.
For example, with the RANGE
switch set to 10 and a PERCENT INPUT meter indication of 80 percent the input
voltage must be approximately 8 volts.
(3) Set the MODE switch to AC TRANSFER. The galvanometer can now be nulled
as follows: set the SENSITIVITY switch on LOW and tap the GALV switch to MOMENTARY.
Observe the deflection on the galvanometer; if it deflects left, turn the REFERENCE
ADJUST COARSE control clockwise until the galvanometer reads zero, if the
galvanometer deflects right, adjust the COARSE control counterclockwise until the
galvanometer reads zero.
(4) Once the galvanometer reads zero in the LOW SENSITIVITY position, go to
the MEDIUM SENSITIVITY position and again use the GALV switch and the MEDIUM and
FINE REFERENCE ADJUST controls for zero on the galvanometer.
(5) After you zero the galvanometer in the MEDIUM position, go to the HIGH
position and again, tapping the GALV switch, adjust the FINE REFERENCE ADJUST
control until the galvanometer indicates zero. After this final zero, do not touch
the REFERENCE ADJUST controls again.
(6) Disconnect the AC input and connect a DC voltage standard to the DC
INPUT terminals. From the foregoing procedure, you know that the unknown is about
8 VAC, 80 percent of the 10 range, so you can set the DC voltage standard for about
8 VDC output. Set the MODE switch to DC SEARCH and the PERCENT INPUT meter should
indicate about 80 percent.
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