3 Calibration Procedures
70 Keysight E3633A and E3634A Service Guide
Common Mode Current Noise
The common mode current is that ac current component which exists between
the output or output lines and chassis ground. Common mode noise can be a
problem for very sensitive circuitry that is referenced to earth ground. When a
circuit is referenced to earth ground, a low level line-related ac current will flow
from the output terminals to earth ground. Any impedance to earth ground will
create a voltage drop equal to the output current flow multiplied by the
impedance.
1 Turn off the power supply and connect a 100 kΩ resistor (R
S
) and a 2200 pF
capacitor in parallel between the (-) terminal and chassis ground.
2 Connect a digital voltmeter across R
S
.
3 Turn on the power supply. Select the 8V/20A
[1]
or 25V/7A
[2]
range, enable the
output, and set the display to the limit mode. When the display is in the limit
mode, program the output to the full rated value (8.0 V and 20.0 A)
[1]
or (25.0
V and 7.0 A)
[2]
.
4 Record the voltage across R
S
and convert it to current by dividing by the
resistance (DVM reading/100 kΩ). Note that the current is less than 1.5 μA.
[1] For Keysight E3633A Model
[2] For Keysight E3634A Model
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