Elgar SW5250A Service Manual download pdf (Page 43)

SERVICE MANUAL CALIBRATION

3-7

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

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Elgar SW5250A Service Manual Page 43