Verification 21
Table 2-5. Constant Current (CC) Tests (continued)
Action
Normal Result
CC Load Effect (cont)
4 Observe the DVM reading. Divide this by the resistance of the current
monitoring resistor to obtain the output current. Record the result.
You may want to use an averaged
reading for this measurement.
5 Short the Electronic Load input and repeat Step 4.
You may want to use averaged reading
for this measurement.
6 Check the result.
The difference between the current
readings taken in Step 4 and Step 5 must
be within specified “Load Effect” limits.
CC Source Effect
This test measures the change in output current resulting from a change in ac line voltage from its minimum to its maximum
value within the line voltage specifications. It is recommended that you use averaged readings for Steps 6 and 8 of this test
(see "Averaging AC Measurements" at the end of this chapter).
1 Turn off the power supply and connect the ac power input through a
variable-voltage transformer.
2 Set the transformer to the nominal ac line voltage. Connect the DVM
across the current monitoring resistor (see Figure 2-1).
3 Turn on the power supply and program the current to its full-scale value
and the voltage to its maximum programmable value (see Table 2-2).
4 Set the Electronic Load to CV mode and its voltage to full scale.
The power supply output current is full
scale and its CC annunciator is on. If
not, reduce the Electronic Load voltage
slightly until the annunciator comes on.
5 Adjust the transformer to decrease the ac input voltage to the low-line
condition (174Vac or 191Vac).
6 Observe the DVM reading. Divide this voltage by the resistance of the
current monitoring resistor to obtain the output current. Record the result.
You may want to use an averaged
reading for this measurement.
7 Adjust the transformer to increase the ac input voltage to the high-line
condition (220Vac or 250Vac).
8 Observe the DVM reading. Divide this voltage by the resistance of the
current monitoring resistor to obtain the output current. Record the result.
You may want to use an averaged
reading for this measurement.
9 Check the test result. The difference between the current
readings found in Step 6 and Step 8 is
within the specified current Source
Effect limits.
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