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Verification and Performance Tests - 2
19
CC Noise (PARD)
Periodic and random deviations (PARD) in the output combine to produce a residual ac current, as well, as an ac
voltage superimposed on the dc output. Constant current (CC) PARD is specified as the rms output current in a
frequency range 20 Hz to 20 Mhz with the supply in CC operation.
a. Turn off the supply and connect the load, monitoring resistor, and rms voltmeter across the monitoring resistor
as shown in Figure 2-1a. The Current Monitoring resistor may have to be substituted by one with a higher
resistance and power rating, such as a 1 ohm 50 W current shunt in series with the appropriate 3, 24, or 99 ohm
resistor, to get the RMS voltage drop high enough to measure with the RMS voltmeter. Leads should be as short
as possible to reduce noise pick-up. An electronic load may contribute ripple to the measurement so if the RMS
noise is above the specification a resistive load may have to be substituted for this test.
b. Check the test setup for noise with the supply turned off. Other equipment (e.g. computers, DVMs, etc.) may
affect the reading.
c. Turn on the supply and program the current to full scale and the output voltage to the maximum programmable
value.
d. The output current should be at the full scale rating with the CC annunciator on.
e. Divide the reading on the rms voltmeter by the monitor resistor to obtain rms current. It should not exceed the
values listed in the performance test record card under CC NOISE (RMS).
Performance Test Equipment Form
Test Facility:_________________________
Report Number ________________________
____________________________________ Date _________________________________
____________________________________ Customer _____________________________
____________________________________ Tested By ____________________________
Model ______________________________ Ambient Temperature (C) ________________
Serial No. ____________________________ Relative Humidity (%) ___________________
Options _____________________________ Nominal Line Frequency __________________
Firmware Revision ____________________
Special Notes:
Test Equipment Used:
Description Model No. Trace No. Cal. Due Date
AC Source
_________________ _________________ _________________
DC Voltmeter
_________________ _________________ _________________
RMS Voltmeter
_________________ _________________ _________________
Oscilloscope
_________________ _________________ _________________
Electronic Load
_________________ _________________ _________________
Current Shunt
_________________ _________________ _________________
_________________ _________________ _________________