Keysight Technologies RP7900 Series, Operating And Service Manual

Page: 265 / 318

Measurement Setups
Voltmeter
To ensure that the values read by the voltmeter during both the verification procedure and the
calibration procedure are not affected by the instantaneous measurement of the AC peaks of the
output current ripple, make several DC measurements and average them.
If you are using a Keysight 3458A DMM, you can set up the voltmeter to do this automatically. From
the instrument’s front panel, program 100 power line cycles per measurement. Press NPLC 100
ENTER. Additionally, turn on auto-calibration (ACAL) and the autorange function (ARANGE).
Current Shunt
The 4-terminal current shunt is used to eliminate output current measurement error caused by
voltage drops in the load leads and connections. It has special current-monitoring terminals inside the
load connection terminals. Connect the voltmeter directly to these current-monitoring terminals.
Electronic Load
Many of the test procedures require the use of a variable load capable of dissipating the required
power. For all tests, a Keysight RP79xxA unit can be used as a load, provided that its voltage rating is
equivalent to the unit under test. The RP79xxA load unit is considerably easier to use than load
resistors.
Fixed load resistors may be used in place of a variable load, with minor changes to the test
procedures. To avoid contact with any high voltages during operation, use switches to connect,
disconnect, or short the load resistors.
Also, if computer controlled test setups are used, the relatively slow (compared to computers and
system voltmeters) settling times and slew rates of the RPS may have to be taken into account. "Wait"
statements can be used in the test program if the test system is faster than the RPS.
Keysight RP7900 Series Operating and Service Guide 265
6 Verification and Calibration