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Table 3-2. DC Voltage
Performance
Check (2V to 1200V
Rangel
3.4.3 DC Voltage
Accuracy
Check (20mV and 200mV
Rangesl
1. Select
DCV and 20mV range.
2. Disconnect
test leads at the DC calibrator
and short
them.
Adjust
Model
177 front panel ZERO for a display
indication
of O.OOOmV *O.OOlmV
flashina.
3. Connect
the DC calibrator
and select 200mV
range.
4. Set the DC calibrator
to an output
of +O.l9OOOOV.
5. Verify that the Model 177 reading is between
+ 189.89 to
+ 190.11mV.
Note that the allowable
reading includes
a
i2
digit
allowance
for
the
uncertainty
of the
DC
calibrator.
Table 3-3. AC Voltage
Accuracy
Check
Range
Applied
Voltage
@lkHz
lOO.OOmV
1 .oooov
1o.ooov
1oo.oov
1ooo.ov
@45Hz
1o.ooov
@2OkHz
1o.ooov
Allowable
Readings at
180 to 28Y.z
6. Repeat steps 4 and 5 with negative
voltage.
7.
Select 20mV M"Qc?.
8. Connect
the
DC calibrator,
low thermal
resistor
and
Model 177 as shown
in Figure 3-1.
9. Temporarily
disconnect
the leads from the DC calibrator
and short them. Adjust Model 177 front panel ZERO for a
display
indication
of 0.000
* O.OOlmV flashing.
10. Set the DC calibrator
to an output
of +O.l9OOOOV.
200mV
2v
2ov
2oov
1ooov
99.35 to 100.65mV
0.9935 to 1.0065V
9.935 to 10.065V
99.35 to 100.65V
993.5 to 1006.5V
2ov
2ov
9.915 to 10.085V
9.915 to 10.085V
11. Verify that the Model
177 readin
is between
+ 18.987
3.4.5 Resistance
KU Accuracy
Check
~~^^_^
.,~
3. Set the DMM to the 200mV
range and apply 1OOmV AC
to the
DMM.
The reading
must
be within
the limits
specified
in Table 3-3.
4. Select the 2,20 and 200mV ranges and apply the required
voltages
as specified
in Table 3-3. Verify that the readings
are within
spcifications.
5. To
check
1OOOV range,
connect
the
AC
calibrator
amplifier
to the output
of the AC calibrator
per the
manufacturer's
instructions.
Connect the amplifier
output
to the Model 177 INPUT terminals.
Set the AC calibrator
for amplifier
output
of lOOO.OOOV at 1kHz. Verify that the
DMM
reading is within
the specified
limits in Table 3-3.
6.
To check accuracy
at 45kHz and 20kHz.
select the 20V
range. Apply
the voltage
specified
in Table 3-3 at 45Hr.
then repeat at 20kHz.
Verify that the DMM
readings are
within
the specified
limits.
1
I
ancl + IY.VIXnV.
Note, that,
the allowable
reading
in-
cludes
*2
digits for DC calibrator
uncertainty
and * 1
1. Select resistance
function
by depressing
n pushbuttons.
digit for low thermal
resistor uncertainty.
2.
Select 2000 range.
12. Repeat steps 10 and 11 with negative
voltage.
3. Connect
the decade
resistor to the DMM.
4. Set the decade
resistor to zero and compensate
for lead
resistance
by adjusting
front panel ZERO for a display in-
THERMAL
dication
00.10 f .OlQ flashing.
R6SlSTOR
5. Set the decade resistor to 190% Verify that the reading for
the 200R range is within
the limits specified
in Table 3.4.
6.
Select the 2k0 ra"Qe.
7.
Set the decade resistor to zero and measure the resistance
of the test leads. Subtract
this reading from the displayed
reading
in all of the following
steps.
Figure 3-I. Test Circuit
For 20mV DC Accuracy
Check
8. Set the decade resistor to 1.900kfI.
Verify that the reading
is within
the limits specified
in Table 3-4.
9. Continue
by selecting
the next range and measure the next
3.4.4 AC Voltage
Accuracy
Check
resistance
as specified
in Table 3-4. Test each item in the
1. Select
AC voltage
function
with
the
AC/DC
and V
table and verify that each reading is within
specifications.
pushbuttons.
2. Connect
the AC calibrator
to the DMM.
Set the calibrator
frequency
to 1 kHz.
3-2
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