Appendix Service Information
Constant Current (CC) Verifications
191
Service
Information
3 Set the voltage of the electronic load to (8.0 V)
†
to operate it in constant voltage mode
since a voltage drop occurs on the load wires. Check that the
CC annunciator is on.
If it is not, adjust the load so that the output voltage drops slightly. Record the current
reading by dividing the voltage reading on the digital voltmeter by the resistance of
the current monitoring resistor.
4 Operate the electronic load in short (input short) mode. Record the current reading
immediately 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 during the
immediate change should be within the limit of:
5 Repeat steps (1) through (4) for the other output.
CC Source Effect (Line Regulation)
This test measures the immediate 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).
1 Turn 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 (R
M1
).
2 Connect the ac power line through a variable voltage transformer.
3 Turn 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 maximum programmable value and the current to the full rated value
(3 A)
†
.
4 Operate 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.
5 Adjust the transformer to low line voltage limit (104 Vac for nominal 115 Vac, 90
Vac for nominal 100 Vac, or 207 Vac for nominal 230 Vac). Record the output current
reading by dividing the voltage reading on the digital voltmeter by the resistance of
the current monitoring resistor.
E3646A E3647A E3648A E3649A
0.55 mA 0.33 mA 0.75 mA 0.39 mA
†
For E3646A model, and see Table A-3 for other models
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