Contact the factory for a Repair Authorization Number and return instructions if service is
required. A Repair Authorization (RA) number will be assigned for proper handling of the unit
when it arrives at the factory. Any non-warranty repair cost incurred for the repair or replacement
of parts and/or materials shall be the responsibility of the purchaser.
Provide the factory with model number, Unit serial number, serial number of VI-Gen if
appropriate, nature of the problem or service, return address, your name, and how to contact you
should the factory need to discuss the service request.
You may need to provide a purchase order number, cost limit, billing, and return shipping
instructions.
If an estimate is requested, provide the name and contact information.
6.4
Calibration Check
Prerequisites
For best accuracy, it is recommended that tests be conducted at a normal ambient operating
temperature of 25
°
C ± 5
°
C. When testing AC and DC current outputs it is best to limit the test
time to a minimum to make an accurate measurement. This will limit the accuracy drift due to the
heating effect of the output current (normally only applicable to test currents of 15 Amperes, or
above, for extended test periods). It is also recommended that current measurements start on the
low range first and progress to the higher ranges. For best results it is also recommended that the
amplifier be allowed to cool down between tests. Cool down time will vary depending on the
ambient temperature and the test current applied.
Test Equipment/Minimum Requirements
Measurements must be made with equipment that is more accurate than the Unit Under Test
(UUT). The instruments listed below are recommended. If equivalent instruments are not
available, then total measured accuracies of the measuring instrument and the UTT will need to
be to taken into account.
Digital Multimeter DCV ± 0.0625% Keithley 197A or equivalent.
Current shunt DCA
±
0.0625% w/c.f. or equivalent
Yokogawa ACV
±
0.025%, ACI
±
0.025% WT-3000 or equivalent.
Phase angle meter
±
0.0125
°
, North Atlantic 2000 or equivalent.
Counter
±
1.8X10-6, H.P. 5335A or equivalent.
Counter
±
3 PPM, Fluke PM6680 or equivalent.
Multi-calibrator
±
0.0125% DCA/DCV
Power Multimeter, Megger Model PMM-1 or equivalent
Notes and Precautions
High voltages and high currents used in this calibration check.
Allow UUT and equipment a minimum of ½ hour warm-up time for best results.
Allow sufficient cool down between tests on the current channels to eliminate possible
accuracy drift due to heating.
-
163
www
. ElectricalPartManuals
. com
