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Verification 21
Table 2-5. Constant Current (CC) Tests (continued)
Action Normal Result
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 Fig. 2-3).
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 (180Vac or 360Vac).
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 (235Vac or 440Vac).
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.