Appendix Service Information
Constant Current (CC) Verifications
176
4Operate the electronic load in short (input short) mode. Record the current
reading again by dividing the voltage reading on the digital voltmeter by the
resistance of the current monitoring resistor. The difference between the
current readings in step (3) and (4) is the load regulation current. The
difference of the readings should be within the limit of:
CC Source Effect (Line Regulation)
This test measures the change in output current that results from a change in
ac line voltage from the minimum value (10% below the nominal input voltage)
to the maximum value (10% above nominal voltage).
1Turn off the power supply and connect the output to be tested as shown in
Figure A-1 with the digital voltmeter connected across the current monitoring
resistor (RM1).
2Connect the ac power line through a variable voltage transformer.
3Turn on the power supply. Select the low voltage range (8V/3A)†, enable the
output, and set the display to the limit mode. When the display is in the limit
mode, program the voltage to the full scale rated value (8.0 V)† and the current
to the full scale rated value (3 A)†.
4Operate the electronic load in constant voltage mode and set its voltage to
(8.0 V)†. Check that the CC annunciator remains lit. If not lit, adjust the load
so that the output voltage drops slightly until the CC annunciator lights.
5Adjust the transformer to low line voltage limit (104 Vac for nominal 115 Vac,
90 Vac fo r no minal 100 Vac, or 20 7 Vac for no minal 230 Vac). Record the output
current reading by dividing the voltage reading on the digital voltmeter by the
resistance of the current monitoring resistor.
6Adjust the transformer to 10% above the nominal line voltage (127 Vac for a
115 Vac nominal input, 110 Vac for a 100 Vac nominal input or 253 Vac for a
230 Vac nominal input). Record the current reading again by dividing the
voltage reading on the digital voltmeter by the resistance of the current
monitoring resistor. The difference between the current readings in step (5)
and (6) is the load regulation current. The difference of the readings should be
within the limit of:
E3640A E3641A E3642A E3643A E3644A E3645A
0.55 mA 0.33 mA 0.75 mA 0.39 mA 1.05 mA 0.47 mA
E3640A E3641A E3642A E3643A E3644A E3645A
0.55 mA 0.33 mA 0.75 mA 0.39 mA 1.05 mA 0.47 mA
†For E3640A model, and see Table A-3 for other models