Cal Power TrueWave TW5250 Service Manual page 43

SERVICE MANUAL
Measure the current offset by sending the following GPIB query and record the return
string as MEAS1:
MEAS{1,2,3}:CURR?
Calculate the offset value:
VALUE1 = -1.0 * MEAS1
Send the calculated offset to the TW:
CAL{1,2,3}:MEAS:LOC:HIR:CURR:OFFSET VALUE1
Set the TW to 440 volts DC by sending the following GPIB string:
SOUR{1,2,3}:VOLT:OFFSET 440
Wait for the DMM to settle. Take a DMM reading and record the value as RDGN1.
Query the output voltage of the TW and record the return string as MEAS1:
MEAS{1,2,3}:VOLT?
Set the TW to -440 volts DC by sending the following GPIB string:
SOUR{1,2,3}:VOLT:OFFSET –440
Wait for the DMM to settle. Take a DMM reading and record the value as RDGN2.
Query the output voltage of the TW and record the return string as MEAS2:
MEAS{1,2,3}:VOLT?
Calculate the gains and offset for the phase being calibrated:
GAIN1 = (MEAS1 – MEAS2) / (RDGN1 – RDGN2)
GAIN2 = (880.0) / (MEAS1 – MEAS2)
OFFSET = GAIN2 * MEAS1 – 440.0
Update the TW calibration registers by sending the following GPIB strings:
CAL{1,2,3}:MEAS:LOC:HIR:VOLT:GAIN GAIN2
CAL{1,2,3}:OUTP:LOC:HIR:VOLT:GAIN GAIN1
CAL{1,2,3}:OUTP:LOC:HIR:VOLT:OFFSET OFFSET
Reset the TW's output to a safe condition:
SOUR{1,2,3}:VOLT:OFFSET 0.0
OUTPUT OFF
CALIBRATION
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