Technical data

8 Service and Maintenance
Constant Current (CC) Verifications
198 E364xA User’s and Service Guide
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 the nominal voltage).
1 Turn off the power supply and connect the output to be
tested as shown in
Figure 8- 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
(8 V/3 A)
[1]
, 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- scale rated value (3 A)
[1]
.
4 Operate the electronic load in the constant voltage mode
and set its voltage to 8.0 V
[1]
. 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 up.
5 Adjust the transformer to the 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.
6 Adjust 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 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 5 and
step 6 is the load regulation current. The difference of the
readings during the immediate change should be within
the following limits:
[1] For the E3640A model. For other models, refer to Tabl e 8 -5 .