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871A & 871AB
END-SCALE
DEFLECTION
|
NULL
|
VOLTAGE
|
|
SWITCH
|
DIALS
1100-0-1100
No effect
110-0-110
No effect
11-0-11
No effect
1.1-0-1.1
No effect
0.11-0-0. 11
All zero
070112020 000
All zero
| 0. 0011-0-0. 0011
|
All zero
Figure 2-1.
VTVM RANGES
2-9.
MEASUREMENT OF VOLTAGE EXCURSIONS ABOUT A NOMINAL VALUE
a.
Perform preliminary operation as stated in paragraph 2-1 or 2-2.
b.
Connect voltage to be observed between INPUT and COMMON
posts.
If
one side is grounded,
always connect it to COMMON
post.
Deflection to the
left indicates voltage being measured is negative; set polarity switch to negative
position in this case.
This will cause meter needle to deflect to the right.
c.
Set RANGE
switch to lowest range which will give an on-scale meter
indication and note nominal value of voltage indicated.
d.
Set the four voltage readout dials to nominal voltage.
e.
Turn NULL
switch to lowest position that will allow voltage excursions
to remain
on scale.
l
f.
Read voltage excursions from meter.
Note that full scale right and
left meter deflections are equal to the NULL
range setting (disregarding
10% over-range at end of scale).
Meter deflection to the right indicates
that the voltage under observation has increased above the nominal value
while deflection to the left indicates it has decreased.
2-4
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