Electrical Test Instruments MAC-21
Section III
–
MAC-21
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Copyright(C) 1994-2004 Electrical Test Instruments, LLC All Rights Reserved
Page III-8
important, because waveform distortion is more prevalent at lower levels.
7.
If the MAC-21 reading differs from the standard by more than rated
accuracy, adjust the gain potentiometer on the analog board for proper
reading. If an error of more than 5% is noted, and unit has been in service,
the accuracy and validity of previous tests may be questionable; otherwise,
there may be a problem in the test setup.
8.
Check calibration at 200, 400, 600, and 1000 Amperes.
9.
Adjust the current to zero, and press RESET key.
10.
Raise the current slowly, until the timer begins to run. This is the Current
Latch Threshold, which should be about 10% of range.
11.
Set the current at 50% of full scale (500 A) and stop the current.
12.
Set the MAC-21 to MEMORY mode and press the RESET Switch.
13.
Initiate a fast-momentary pulse of no more than 6 cycles (0.1 Sec) duration.
The meter should read the same value, within 1% of r 1% of range,
that was set in step 11 above.
14.
Check pulse reading operation in this manner for currents of 200, 400, 600,
and 1000 Amperes, and varying duration.
15.
Set Timer Time base to SECONDS. Press Master Reset Switch. Set N.O.
mode. Using a stopwatch, initiate for exactly ninety (90) seconds. Timer
should read 90.00 Seconds, +/- 0.01 Seconds. (Note: actual reading may
vary because of inability to control and measure pulse length.)
16.
If everything checks out, the MAC-21 can be assumed to be in calibration,
and no other adjustments are required.
