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6 Verification and Calibration
Step 3. Divide the voltage drop (DMM reading) across the current shunt by the shunt resistance to
convert to amps and record this value.
Step 4. Turn off the unit under test and connect the RP79xxA load unit between the current shunt and
the output terminals (see
Test Setup
B).
Step 5. Set the RP79xxA load for voltage priority mode and program its voltage and current limit as
described in the test record under "CC Load Effect". Enable the load's output.
Step 6. Program the unit under test to the settings as described in the test record under "CC Load
Effect". Enable the output of the unit under test. The output status should be "CC". If it isn't, adjust the
load so that the output voltage drops slightly.
Step 7.Divide the voltage drop (DMM reading) across the current shunt by the shunt resistance to
convert to amps and record this value. The difference in this current reading and the reading in step 3
is the load effect, which should not exceed the value listed in the test record for the appropriate model
under "CC Load Effect".
Current Sink Capability Verification
This test checks the ability of the power supply to sink up to 100% of its rated output current.
Step 1. Turn off the unit under test and connect the RP79xxA unit as an external source to the + and -
output terminals (see
Test Setup
B).
Step 2. Set the RP79xxA external source for voltage priority mode and program it to the voltage as
described in the test record under "100%of Current Rating (Isink)".
Step 3. Turn on the unit under test. Set the operating mode to current priority. Program the instrument
settings as described in the test record under "100%of Current Rating (Isink)".
Step 4. Check the front panel display of the unit under test and verify that it is sinking 100% of its rated
current and has a -CL status. Divide the voltage drop (DMM reading) across the current shunt by the
shunt resistance to convert to amps and record this value. The readings should be within the limits
specified in the test record form under "Current Sink Tests".
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Keysight RP7970 & RP7980 Series Operating and Service Guide
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