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B - Performance, Calibration, and Configuration
150
f. Turn on the dc source and set the current range readback to 3A. Program the output voltage to zero
and the current to full scale as in Table B-2.
g. Record the current reading on the front panel display. Divide the voltage drop (DVM reading) across
the current monitoring resistor by its resistance to convert to amperes and record this value. The
difference between the two current readings should be within the limits specified in the performance
test record card under 3A Range Current Readback Accuracy @ −3A.
CC Load and Line Regulation (performance)
The following CC Load Effect and CC Source Effect tests verify the dc regulation of the output current.
To insure that the values read are not the instantaneous measurement of the ac peaks of the output current
ripple, several dc measurements should be made and the average of these readings calculated. An
example of how to do this is given below using an Agilent 3458A System Voltmeter programmed from
the front panel. Set up the voltmeter and execute the "Average Reading" program follows:
a. Program 10 power line cycles per sample by pressing NPLC 1 0 ENTER .
b. Program 100 samples per trigger by pressing (N Rdgs/Trig) 1 0 0 ENTER .
c. Set up voltmeter to take measurements in the statistical mode as follows:
Press Shift key, f0, Shift key, N
Press ^ (up arrow) until MATH function is selected, then press >.
Press ^ (up arrow until STAT function is selected then press (ENTER).
d. Set up voltmeter to read the average of the measurements as follows:
Press Shift key, f1, Shift key, N.
Press down arrow until RMATH function is selected, then press >.
Press ^ (up arrow) until MEAN function is selected, then press ENTER.
e. Execute the program by pressing f0, ENTER, TRIG, ENTER
f. Wait for 100 readings and then read the average measurement by pressing f1, ENTER.
To repeat the measurement, perform steps (e) and (f).
CC Load Effect (performance)
This test measures the change in output current for a change in load from full scale output voltage to
short circuit.
a. Turn off the dc source and connect the output as shown in Figure B-1b with the DVM connected
across the current monitoring resistor.
b. Turn on the dc source and if it was set to low range readback in the previous test, set it back to high
or auto. Program the current to full scale and the output voltage to the maximum programmable
voltage value (Vmax) in Table B-2.
c. Adjust the load in the CV mode for the UUT full scale voltage in Table B-2 as indicated on the front
panel display. Check that the CC annunciator of the UUT is on. If it is not, adjust the load so that the
output voltage drops slightly.
d. Record the output current reading (DVM reading/current monitor resistance value in ohms). You
may want to use the average reading program described under “CC Load and Line Regulation”.
e. Short the load switch and record the output current reading. The difference in the current readings in
steps (d) and (e) is the load effect and should not exceed the limit specified in the performance test
record card for the appropriate model under CC Load Effect.