User`s guide

Chapter 3 Calibration Procedures

Constant Voltage (CV) Verifications

CV PARD (Ripple and Noise)

Periodic and random deviations (PARD) in the output (ripple and noise) combine to

produce a residual ac voltage superimposed on the dc output voltage. CV PARD is

specified as the rms or peak-to-peak output voltage in the frequency range from 20

Hz to 20 Mhz.

• VRMS measurement techniques:

When measuring Vrms ripple and noise, the monitoring device should be plugged into

the front of the terminals at (B) in Figure 3-2. Use the coaxial cable and BNC female

to banana plug adapter to connect the monitor device to the power supply. To reduce

the measurement error caused by common mode noise, it is recommended that you

use a common mode choke between the cable and the BNC adapter. The common

mode choke is constructed by inserting coaxial cable into Ferrite Toroidal core. The

load resistor should be connected to the terminal at (A) in Figure 3-2. Twisted leads

between the load resistor and the power supply helps reduce noise pickup for these

measurements.

1 Turn off the power supply and connect the output to be tested as shown in Figure 3-

1 to an oscilloscope (ac coupled) between (+) and (-) terminals. Set the oscilloscope

to AC mode and bandwidth limit to 20 MHz. Connect a resistive load (2.0

Ω)* or

(12.5

Ω)** to the terminal at (A) in Figure 3-2.

2 Turn on the power supply. Select the 20V/10A* or 50V/4A** range, enable the output,

and set the display to the limit mode. When the display is in the limit mode, program

the current to the full rated value (10.0 A)* or (4.0 A)** and the voltage to the full

rated value (20.0 V)* or (50.0 V)**.

3 Check that the front panel CV annunciator remains lit. If not lit, adjust the load down

slightly.

4 Note that the waveform on the oscilloscope does not exceed the peak-to-peak limit

of 3 mV.

5 Disconnect the oscilloscope and connect the ac rms voltmeter in its place according

to the VRMS measurement techniques above. The rms voltage reading does not

exceed the rms limit of 0.35 mV* or 0.5 mV**.

*For Agilent E3633A Model **For Agilent E3634A Model