Performance Verification Tests; Zeroing The Calibrator - Fluke 5520A Service Manual

5520A
Service Manual

3-17. Performance Verification Tests

The following tests are used to verify the performance of the 5520A Calibrator. If an out-
of-tolerance condition is found, the instrument can be re-calibrated using the front panel
or the remote interface as described previously in this chapter.
Use the same test equipment and connection methods as used in the preceding calibration
procedures.
Zero the 5520A Calibrator before testing by completing "Zeroing the Calibrator" as
described next.

3-18. Zeroing the Calibrator

Zeroing recalibrates internal circuitry, most notably dc offsets in all ranges of operation.
To meet the specifications in Chapter 1, zeroing is required every 7 days, or when the
5520A Calibrator ambient temperature changes by more than 5 C. There are two zeroing
functions: total instrument zero (ZERO) and ohms-only zero (OHMS ZERO). Before
performing the verification tests, perform the total instrument zero.
Complete the following procedure to zero the calibrator. (Note: The 5520A Calibrator
rear panel CALIBRATION switch does not have to be enabled for this procedure.)
1. Turn on the Calibrator and allow a warmup period of at least 30 minutes.
2. Press the
3. Install a low-ohm copper short circuit across the 20 A and AUX LO terminals.
4. Press the
5. Press the CAL softkey, opening the calibration information menu.
6. Press the CAL softkey.
7. Press the ZERO softkey to totally zero the 5520A Calibrator. After the zeroing
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"active," lists output shifts as a result of a calibration just performed but whose
calibration constants are not yet stored.
"consts," which is a listing of the active set of raw calibration constant values.
key.
key, opening the setup menu.
routine is complete (20 minutes), press the key to reset the calibrator.