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II — FEATURES
FRONT PANEL ACCESS. The front panel provides a
power ON/OFF switch controlling input power and a "VDC
ON" light which indicates when the unit is operating.
NOTE: The ON/OFF switch must be set to OFF before
removing unit from rack adapter. The front panel "MAS-
TER ON" LED lights when 1) the unit operates indepen-
dently, or 2) the unit is used in parallel redundant
configurations while a) the output is less than 10% of
nominal or b) the output is within 10% to 100% of nominal
and the unit is functioning as a master. In parallel redun-
dant configurations, the module with the highest voltage
functions as the master. The other units are slaves, and
track the output voltage of the master. Refer to Current
Share Bus (CSB) on page 3 for details. (The "MASTER
ON" LED is not used on 3.3V model; it is always off.) The
front panel Vadj trimmer provides adjustment of the output
voltage within the limits specified in Table 1; test points
connected to the +S and –S lines are available at the front
panel for measuring the output.
BUILT-IN OR-ING DIODES. OR-ing
configuration of all models for hot-swap and parallel-
redundant N+1 operation where current distribution is not
equal and the idle unit takes over in the event of failure.
PS1
3042496
FIGURE 2. HSF-1UR 150 WATT POWER SUPPLIES (4) INSTALLED IN RA 19-1U RACK ADAPTER
FORCED CURRENT SHARE CIRCUIT. (Not
able on 3.3V model). When units are configured for N+1
parallel redundant operation, it is desirable (but not
required) for current to be divided equally among the paral-
leled supplies. When the CSB (forced Current Share Bus)
lines of paralleled HSF-1UR units are connected together,
the load current is forced to divide equally between all par-
alleled units; units operate at less than maximum, reducing
stress and increasing reliability of the system. If one unit
fails, the remaining units will continue to supply the load,
and the load current will be divided equally among the
remaining operating units. The failed unit is automatically
isolated from the circuit by a built-in isolation diode. Refer
to Current Share Bus (CSB) on page 3 for details.
REMOTE ON-OFF. Remote on/off control (X and Y
models only) is via ±RC assigned to pins of the RA 19-1U
I/O connector: off = no voltage, short circuit, or 0 to 0.8V,
KEPCO, INC. 131-38 SANFORD AVENUE FLUSHING, NY. 11355 U.S.A. TEL (718) 461-7000 FAX (718) 767-1102
2
diodes
allow
PS2
avail-
http://www.kepcopower.com email: hq@kepcopower.com
228-1621 REV 8
t
T
3043527
24V Model can supply Peak current listed in Table 1 if the
four conditions listed below are met. This model includes
thermal protection, voltage shutdown type. Restart by
removing a-c input; after sufficient cooling, reapply a-c
input (wait at least 30 seconds).
1. Time: t 10 Seconds
2. I
Peak Current (Amperes)
1
3. Effective Current:
2
2
Rated current (Amperes)
I 2
+
–
DI 1
I D
4. Effective Power P Maximum Power (Watts)
(output RMS current x output voltage)
FIGURE 1. PEAK CURRENT REQUIREMENTS
PS3
on = 4.5 to 12.5V (or 12.5 to 24.5V via 1.5K Ohms). To
reverse on-off polarity contact Kepco. There is no isolation
between ±RC, d-c output and alarm circuit. Refer to the
RA 19-1U Manual for details. NOTE: POWER switch must
be ON for remote control to be active.
CURRENT MONITOR. Current monitor (C and Y
models only) is via ±IMON assigned to pins of the RA 19-
(X)B I/O connector. Monitored Output Current (Amps) =
Voltage drop across R
EQ
R
is the sum of R
(see Table 1) + trace resistance to
EQ
S
point where current monitor is connected, approximately
4mOhms. The voltage drop across R
across ± IMON pins (requires millivoltmeter, range 0 to
250mV). Accuracy is ±10%; contact Kepco if greater
accuracy is required. There is no isolation between
±IMON, alarm circuit and d-c output. Refer to the applica-
ble RA 19-1U Manual for details.
D=(t/T)
PS4
(mVolts) / R
(mOhms) where
EQ
is measured
EQ
I 1
I
2
021219
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