Chapter 3 Calibration Procedures
Constant Voltage (CV) Verifications
50
CV Line Regulation
This test measures the change in output voltage that results from a change in
ac line voltage from the minimum value (10% below the nominal input voltage)
to maximum value (10% above the nominal input voltage).
1Turn off the power s upply and conn ect a digital v oltmeter betwee n the (+) and
(-) terminals of the output to be tested as shown in Figure 3-1.
2Connect the ac power line through a variable voltage transformer.
3Turn on the power supply and select the desired output to be tested using the
meter and adjust selection key on the front panel. Enable the outputs and set
the display to the limit mode. When the display is in the limit mode, program
the current of the selected output to the maximum programmable value and
the voltage to full-scale value (see Table 3-2).
4Operate the electronic load in constant current mode and set its current to the
full scale value (see Table 3-2) of the output to be tested. Check that the front
panel CV annunciator remains lit. If not lit, adjust the load so that the output
current drops slightly until the CV annunciator lights.
5Adjust the transformer to low line voltage limit (104 Vac for nominal 115 Vac,
90 V ac fo r n om in al 10 0 Va c, or 20 7 V ac fo r no mi na l 2 30 Va c) . R e co rd th e o ut pu t
reading on the digital voltmeter.
6Adjust the autotranformer to high line voltage (127 Vac for nominal 115 Vac,
110 Vac for nominal 100 Vac, or 253 Vac for nominal 230 Vac). Record the
voltage reading on the digital voltmeter. The difference between the digital
voltmeter readings in steps (5) and (6) is the CV line regulation. The difference
of the readings should be within the limit specified below for each output
tested.
7Repeat steps (1) through (6) for the remaining outputs.
Output Difference
+6V 2.6 mV
+25V 4.5 mV
-25V 4.5 mV