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3-1 TURN-ON CHECKOUT PROCEDURE
3-2
The following checkout procedure describes the
use of the voltage control and ensures that the supply
is operational.
a. Before connecting input power to unit, connect
external voltmeter across +S and —S terminals at rear
terminal board.
b. Connect unit to input power source using
AC, ACC. and ground terminals at rear. (Use proper
wire size in accordance with the input AC current
rating.)
c. Observe output voltage of supply on external
meter. Output is factory set to nominal voltage. If de¬
sired. VOLTAGE ADJUST (screwdriver control, ac¬
cessible through cutout on front panel) potentiometer
can be used to set output to any voltage within adjust¬
ment span (±0.5 V or ±5% as applicable).
NOTE
The current limit may require readjust¬
ment if the output voltage is set away
from nominai. Refer to Paragraph 3-8.
d. To verify operation of current limit circuit,
remove voltmeter and disconnect input power. Connect
short across output terminals of supply and reconnect
input power. Using clip-on milliammeter (HP Model
428B, or equivalent) observe that short circuit output
current is approxi mately 3% to 15% of rated output
current.
e. Remove short and milliammeter. Before con¬
necting actual load to supply, read the following para¬
graphs.
3-3 OPERATION
3-4
The supply can be operated in one of two oper¬
ating modes; normal or remote sensing. Auto-Series,
Auto-Parallel, Auto-Tracking and remote programming
operation are not feasible with this supply. The follow¬
ing paragraphs describe both of those modes plus
supplementary operating information. More theoreti¬
cal descriptions regarding the operational features of
power supplies in general are given in application note
90A, DC Power Supply Handbook (available at no
charge from your local HP sales office).
3-5 Normal Operating Mode
3-6
The power supply is shipped with the rear term¬
inal straps connected for Constant Voltage/Current
Limiting, local sensing, operation. This strapping
pattern is illustrated in Figure 3-1. Before connecting
a load to the supply, check the rear terminals to ensure
that the connections are correct and that the connect¬
ing straps are tightened securely.
3-7 Current Limit
3-8
Figure 3-2 shows typical current limiting charac¬
teristics for all HP modular supplies. As indicated on
the drawing, the current limit point varies in accord¬
ance with the output voltage. As received from the
factory, the initial current limit point is set to 104 ±1 %
of the current rating with the output voltage at its
nominal value. This same current limit setting is recom¬
mended for ail output voltages within the adjustment
span because: (1) the current limit crossover point
must be at least 3% higher than the maximum expected
operating current to prevent performance degradation;
and (2) a current limit setting of higher than 105% of
rating creates the possibility of excessive internal heat¬
ing as specified in the caution note of Figure 3-2. Hence,
the current limit potentiometer (accessible through a
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