User`s guide

Verification and Calibration Appendix B
Series N5700 User’s Guide 97
CV Source Effect
Test category = performance
This test measures the change in output voltage that results from a
change in AC line voltage from the minimum to maximum value
within the line voltage specifications.
1 Turn off the power supply and connect the ac power line through
a variable voltage transformer.
2 Connect a DVM and an electronic load as shown in figure A. Set
the variable voltage transformer to nominal line voltage.
3 Turn on the power supply and program the output current to its
maximum programmable value (Imax) and the output voltage to
its full-scale value.
4 Set the electronic load for the output’s full-scale current. The CV
annunciator on the front panel must be on. If it is not, adjust the
load so that the output current drops slightly.
5 Adjust the transformer to the low-line voltage (85 VAC for
100/120 nominal line; 170 VAC for 200/240 nominal line).
6 Record the output voltage reading from the DVM.
7 Adjust the transformer to the high-line voltage (132 VAC for
100/120 nominal line; 265 VAC for 200/240 nominal line).
8 Record the output voltage reading on the DVM. The difference
between the DVM reading in steps 6 and 8 is the source effect,
which should not exceed the value listed in the test record card
for the appropriate model under CV Source Effect.
CV Noise
Test category = performance
Periodic and random deviations in the output combine to produce a
residual AC voltage superimposed on the DC output voltage. This
residual voltage is specified as the rms or peak-to-peak output
voltage in the frequency range specified in Appendix A.
1 Turn off the power supply and connect the load resistor,
differential amplifier, and an oscilloscope (ac coupled) to the
output as shown in figure C. Use the xx Ω load for 750 W outputs;
use the xx Ω load for 1500 W outputs.
2 As shown in the diagram, use two BNC cables to connect the
differential amplifier to the + and − output terminals. Each cable
should be terminated by a 50 Ω resistor. The shields of the two
BNC cables should be connected together. Connect the output of
the differential amplifier to the oscilloscope with a 50 Ω
termination at the input of the oscilloscope.
3 Set the differential amplifier to multiply by ten, divide by one,
and 1 Megohm input resistance. The positive and negative inputs
of the differential amplifier should be set to AC coupling. Set the
oscilloscope’s time base to 5 ms/div, and the vertical scale to 10
mV/div. Turn the bandwidth limit on (usually 20 or 30 MHz), and
set the sampling mode to peak detect.