3% of range within frequency and voltage ranges
AC accuracy.
listed under "ac accuracy as a differential voltmeter."
DC accuracy.
3% of range.
c. General.
(1) Electrical design.
Completely solid-state.
(2) Input resistance of null detector.
10 megohms for 2 least
sensitive null ranges, all input ranges; 1 megohm for 2 most sensitive null
ranges; all input ranges.
(3) Reference
element.
Temperature-compensated
zener
temperature coefficient less than 1 ppm/C over operating temperature range.
(4) Regulation of reference supply.
0.0002% for 10% line voltage
change.
(5) Stability of reference supply.
0.0005% peak-to-peak per hour.
0.0007% peak-to-peak per day. 0.0013% peak-to-peak per 60 days.
(6) Stability of instrument.
0.00025% peak-to-peak per 60 days.
5% of null range (3% with
(7) Accuracy of off-null deflection.
voltage dials at zero).
(8) Kelvin-Varley divider accuracy. 0.0012% of setting from 1/10 of
full scale to full scale.
0.0012% terminal linearity below 1/10 full
scale.
(9) Recorder output.
Adjustable from 0 to 20 mv minimum for full
scale right and left deflection.
Front panel switch selects DC, -DC and AC.
(10) Polarity.
(11) Warmup time.
dc 30 seconds; ac one minute.
(12) Common mode rejection.
130 db dc; 85 db at 60 Hz; 70 db at 400
Hz.
NOTE
Battery operation of Model 887AB provides complete
isolation from power system ground, for elimination of
error due to ground loops.
0C to 50C (see accuracy)).
(13) Operating temperature range.
98
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