HP 6960A - Page 20

Model 6960 A
b) Current Limiting.
Section V
Switch off Model 6960A under test and connect the Model 412A with the cur-
rent range across the output terminals. Turn the CURRENT LIMIT fully clock-
wise. VOLTAGE ADJUST should be in a mid range position. Push the buttons
18 V-0.6 A or 36-0.3 A and wait 15 minutes. When the instrument has warmed
up measure the maximum short circuit current in both ranges. The 412A should
read
about 340 rnA in the 36V range and 680 rnA in the 18 V range.
c) Ripple.
Attach the load resistor for 18 V and 0.6 A to the output terminals and adjust
the output voltage and current to these ratings. Connect the floating input of
AC-Voltmeter 4038 (or equivalent) ungrounded AC-voltmeter to the output ter-
minals. The readout of the 4038 should not exceed 150 ;UV. In the 36 V-0.3 A
range
the same result should appear.
d) Load regulation.
For the connections, refer to block diagram in Figure 5-1. If the load is switch-
ed off ond on the output voltage change in both ranges should not exceed 5 mV.
Th\" "internal resistance" of the power supply under test should be positive, that
is, with load off the output voltage should be higher than with load on.
If you lock a good differential voltmeter, take a second Model 6960A or another
constant voltage source and compare the output voltage changes to the power
supply under test using a sensitive
DC-voltmeter like the 1j Model 412A or
ilj Model 425 A.
e) Line regulation.
Take the same connections as in paragraph 5-8d, change the line voltage of the
Model 6960A under test by means of a variable Iine transformer between 198 V
and 242
V. The change in output voltage should not exceed 5 mV on both
ranges.
5-3