TB 9-6625-133-40
(7) Press ACI (if necessary) and set TI to the first range in table 9.
NOTE
When using the 1 mA active current shunt, DC current is
used to establish the reference as stated in steps (8) through
(12) below. All other passive current shunts use the DC
resistance value of the current shunt to establish the reference.
(8) Set calibrator current output to +100 uA DC, output to OPR
(9) When indication on AC measurement standard has settled, press SET REF soft
key. Display should be set to indicate PPM units.
(10) Set calibrator current output to -100 uA, output to OPR. When indication on AC
measurement standard has settled, press AVG REF soft key.
(11) Set calibrator frequency to the first 100 uA value in table 9, output to OPR.
(12) Using calibrator edit controls, adjust output until AC measurement standard
indicates as close as possible to the test reported ACDC dif error value of the current shunt
(calibrator resolution is limited 10 ppm).
NOTE
TI averaging may be used for better stability.
(13) Note TI indication. Calculate TI error using the formula below.
CTUAL - NOMINAL
ERROR ppm = A
,
,
NOMINAL
Where:
ACTUAL= TI indication in A
NOMINAL = 100 A
(14) TI will indicate within the limits of table 9. If not, perform b below.
(15) Repeat technique of (11) through (14) above for remaining calibrator frequencies
at 100 uA in table 9. Calibrator may require significant editing at higher frequencies (e.g.
~20% at 10 kHz).
(16) Press CLEAR REF on AC measurement standard.
(17) Set calibrator to STBY, remove and de-energize 1 mA current shunt.
(18) Set TI to the next range in table 9.
(19) Connect current shunt specified in table 9 for this range.
(20) Set calibrator current and frequency for this range to the values in table 9,
output to OPR.
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