Keysight e3620a, Operating And Owners Manual

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A-2
PERFORMANCE TESTS
The following paragraphs provide test procedures for verify-
ing the power supply's compliance with the specifications of
Table 1. Proceed to the troubleshooting procedures if you
observe any out of specification performance.
Before applying power to the supply, make certain
that its line voltage selector switch (S1) is set for the
line voltage to be used. (See CAUTION notice in
operating section for additional information on S1.)
General Measurement Techniques
Connecting Measuring Devices. To achieve valid results
when measuring load regulation, ripple and noise, and transient
response time of the supply, measuring devices must be con-
nected as close to the output terminals as possible. A measure-
ment made across the load includes the impedance of the leads
to the load. The impedance of the load leads can easily be sev-
eral orders of magnitude greater than the supply impedance and
thus invalidate the measurement. To avoid mutual coupling
effects, each measuring device must be connected directly to
the output terminals by separate pairs of leads.
When performance measurements are made at the front ter-
minals (
Figure A-2 ) the load should be plugged into the front
of the terminals at (B) while the monitoring device is con-
nected to a small lead or bus wire inserted through the hole in
the neck of the binding post at (A). Connecting the measuring
device at (B) would result in a measurement that includes the
resistance of the leads between the output terminals and the
point of connection.
Selecting Load Resistors. Power supply specifications are
checked with a full load resistance connected across the sup-
ply output. The resistance and wattage of the load resis-
tor,therefore, must permit operation of the supply at its rated
output voltage and current. For example, a supply rated at 25
Figure A-2. Front Panel Terminal Connections
volts and 1 amp would require a load resistance of 25

at the
rated output voltage. The wattage rating of this resistor would
have to be at least 25 watts.
Electronic Load. Some of the performance test procedures
require to use an electronic load to test the supply quickly and
accurately. An electronic load is considerably easier to use
than a load resistor. It eliminates the need for connecting
resistors or rheostats in parallel to handle the power, and it is
much more stable than a carbon-pile load. It is easier to
switch between load conditions as required for the load regu-
lation and load transient response tests.
Output Current Measurement. For accurate output current
measurements, a current sampling resistor should be
inserted between the load and the output of the supply. To
simplify grounding problems, one end of this sampling resis-
tor should be connected to the same output terminal of the
supply which will be shorted to ground. An accurate voltmeter
is then placed across the sampling resistor and the output
current is calculated by dividing the voltage across the sam-
pling resistor by its ohmic value. The total resistance of the
series combination should be equal to the full load resistance
as determined in the preceding paragraphs. Of course, if the
value of the sampling resistor is very low when compared to
the full load resistance, the value of the sampling resistor may
be ignored. The meter shunt recommended in
Table A-1 , for
example, has a resistance of only 100 m

and can be
neglected when calculating the load resistance of the supply.
Figure A-3 shows a four terminal meter shunt. The load cur-
rent through a shunt must be fed from the extremes of the
wire leading to the resistor while the sampling connections
are made as close as possible to the resistance portion itself.
Figure A-3. Current Sampling Resistor Connections
Rated Output, Meter Accuracy, and Current Limit
To check that all supplies will furnish their maximum rated output
voltage and current, that the front panel meters are accurate,
and that the current limit circuits function, proceed as follows:
Rated Output Voltage and Voltmeter Accuracy
a. With no loads connected: turn on the supply and push the
V1 METER switch in. Connect a DVM between the V1 +
and - terminals and set V1 VOLTAGE control until front
panel voltmeter indicates 17.00 volts.
b. Check the DVM indication. It should be within ±(0.5% + 2
counts) of the front panel voltmeter indication (16.90 to
17.10 V).
c. Set V1 VOLTAGE control clockwise until front panel volt-
meter indicates 25.0 volts.
d. DVM should indicate 25 volts ±(0.5% + 2 counts) (24.675
V to 25.325 V).
e. Repeat steps (a) through (d) for the V2 supply.
Rated Output Current and Ammeter Accuracy
f. Connect the test setup shown Figure A-4 to the V1 sup-
ply's + and - output terminals.