Measurement Techniques
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. If a variable resistor is used, switches should be used to connect, disconnect, or short the load
resistor. For most tests, an electronic load can be used. The electronic load is considerably easier to
use than load resistors, but it may not be fast enough to test transient recovery time and may be too
noisy for the noise (PARD) tests.
Fixed load resistors may be used in place of a variable load, with minor changes to the test
procedures. Also, if computer controlled test setups are used, the relatively slow (compared to
computers and system voltmeters) settling times and slew rates of the power system may have to be
taken into account. "Wait" statements can be used in the test program if the test system is faster than
the power system.
Test Considerations
For optimum performance, all verification and calibration procedures should comply with the
following:
l
Ambient temperature is stable, between 18 and 28 °C.
l
Ambient relative humidity is less than 80%.
l
30 minute warm-up period before verification or adjustment.
l
Cables as short as possible, twisted or shielded to reduce noise.
Keysight N6900/N7900 Series Operating and Service Guide
309
7 Verification and Calibration
Summary of Contents for N6900 Series
Page 1: ...Keysight Advanced Power System N6900 N7900 Series Operating and Service Guide...
Page 2: ......
Page 63: ...1 kW Models Keysight N6900 N7900 Series Operating and Service Guide 63 1 Quick Reference...
Page 64: ...2 kW Models 1 Quick Reference 64 Keysight N6900 N7900 Series Operating and Service Guide...
Page 78: ...2 Installing the Instrument 78 Keysight N6900 N7900 Series Operating and Service Guide...
