Appendix Service Information
Constant Current (CC) Verifications
189
Service
Information
Constant Current (CC) Verifications
Constant Current Test Setup
Follow the general setup instructions in the General Measurement Techniques‚ on
page 182, and the specific instructions will be given in the following paragraphs.
Current Programming and Readback Accuracy
This test verifies that the current programming and GPIB or RS-232 readback
functions are within specifications. Note that the readback values over the remote
interface should be identical to those displayed on the front panel. The accuracy of
the current monitoring resistor must be 0.01% or better.
You should program the power supply over the remote interface for this test to avoid
round off errors.
1 Turn off the power supply and connect a 0.01
Ω current monitoring resistor (R
M1
)
across the output to be tested and a digital voltmeter across the current monitoring
resistor (R
M1
) as shown in Figure A-1.
2 Turn on the power supply. Select the output to be tested and the low voltage range
(8V/3A)
†
and then enable the output by sending the commands:
INST:SEL {OUT1|OUT2}
VOLT:RANG P8V
(E3646A model)
OUTP ON
3 Program the output voltage to full scale rated voltage (8.0 V)
†
and output current to
zero amps by sending the commands:
VOLT 8
(E3646A model)
CURR 0
4 Divide the voltage drop (DVM reading) across the current monitoring resistor (R
M
)
by its resistance to convert to amps and record this value (I
O
). This value should be
within the limit of (0 A ± 10 mA). Also, note that the
CC, Adrs, Limit, and Rmt
annunciators are on.
5 Readback the output current over the remote interface by sending the command:
MEAS:CURR?
†
For E3646A model, and see Table A-3 for other models
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