TB 9-4931-700-50
NOTE
Each time measurement of TI output is directed, a minimum
of four readings should be taken. The first reading should be
disregarded and the other three readings averaged. The
average reading is the indication to be recorded for future
use. The ac/dc voltmeter (A1) indication should be read
between 15 and 20 seconds after thermal transfer standard
(A9) transfers to the dc output.
(3) Measure TI output, using thermal transfer standard in auto mode. Record
(4) Compute and record difference between the indication recorded in (3) above
and TI voltage controls setting. If indication in (3) is large a + (plus) sign is assigned to
difference. If it is smaller, a - (minus) sign is assigned to difference. Convert difference
to percentage retaining assigned sign.
(5) Refer to test report for thermal transfer standard to obtain percentage of
ac/dc difference for 1 V at appropriate frequency.
(6) Add algebraically two percentages obtained in (4) and (5) above. The result is
percentage of TI output error. If TI output error is 0.035 percent or more, perform b(1)
through (3) below.
(7) Repeat technique of (1) through (6) above with autotransformer (A2) set at 105
and 125 V ac. If error does not remain within 0.035 percent and adjustments were not
performed in (6) above, perform b(1) through (3) below and repeat (2) through (6) above.
(8) With decade resistor (A3) set to 22 ohms, connect at input to thermal transfer
standard, using cable (B7).
(9) Repeat technique of (1) through (6) above. The TI output will remain within
specified limits.
(10) Perform technique of (1) through (6), (8), and (9) above, using settings and
(11) Disconnect decade resistor.
(12) Set TI frequency to 1 kHz and voltage range to 1 V.
(13) With thermal transfer standard in manual balance mode and dc output state,
adjust its manual balance controls to obtain an ac/dc voltmeter indication of 1.000000 V
dc.
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