Arc Machines 207 - Manual (Page 63)

MODEL 207A AND 207A-1
OPERATION MANUAL
Doc. No. 740044
Rev F
SECTION VII - CALIBRATION
7.2 CURRENT CALIBRATION
9. DO NOT INSERT THE PROBES UNTIL AFTER THE ARC IS STRUCK.
The high frequency start may damage some meters.
10. Press the SEQ START key.
11. As soon as the arc is struck (after prepurge) insert the Probes into the center
plate test points or into the external shunt if it is being used.
12. During all ODD numbered Levels (100 amperes) the DMM should read as
follows:
Center Plate Test Points.. = 4.00 VDC +/- 0.02 VDC
(3.98 VDC to 4.02 VDC)
AMI External Shunt ....... = 100 mv DC +/- 0.05 mv DC
(99.95 mv to 100.05 mv)
If out of tolerance adjust the “Current Gain” trim resister adjusting screw on
the Center Plate .
13. During all EVEN numbered Levels (10 amperes) the DMM should read as
follows:
Center Plate Test Points.. = 0.400 VDC +/- 0.002 VDC.
(0.398 VDC to 0.402 VDC)
AMI External Shunt ....... = 10 mv DC +/- 0.05 mv DC
(9.95 mv to 10.05 mv)
If out of tolerance adjust the “Current Off Adj” trim resister adjusting screw on
the Center Plate .
NOTE
Repeat Steps 12 and 13 until no adjustment is required.
14. Press the SEQ STOP key.
15. After Postpurge turn the power off, remove all test leads and lower the
computer cover and install the retaining screws.
7.4