©2021, KEPCO, INC
1
Data subject to change without notice
228-1532 REV 16
KEPCO, INC.
131-38 SANFORD AVENUE
FLUSHING, NY. 11355 U.S.A.
TEL (718) 461-7000
FAX (718) 767-1102
www.kepcopower.com
email: [email protected]
I N S T R U C T I O N M A N U A L
KEPCO
An ISO 9001 Company.
HSF-PFC
50W SERIES
KEPCO SINGLE OUTPUT 50 WATT
HOT SWAP PLUG-IN POWER SUPPLIES
I — INTRODUCTION
The Kepco HSF-PFC 50 Watt series hot swappable, high
frequency switching, plug-in power supplies with built in
power factor correction employ forward conversion and are
designed to operate in a fault tolerant power system with
either a-c or d-c input. A thermistor soft-start circuit limits
start-up surge. A built-in forced current share circuit and
OR-ing diodes allow configuration for hot-swap and paral-
lel-redundant N+1 operation.
These power supplies are designed to be installed in
Kepco’s RA 19-(X)B Rack Adapters (Figure 2). RA 19-6B
accepts up to six 150W units, RA 19-7B accepts up to three
150W units, and up to four 50W or 100W units and RA 19-
8B accepts up to eight 50W or 100W units. The applicable
RA 19-(X)B Operator Manual can be downloaded from the
Kepco web site at:
www.kepcopower.com/support/opmanls.htm#ra19-xb
All input/output connections are through a 24 pin connector
that plugs into the rack adapter. All external connections
are made through the rack adapter.
Six standard models may be selected for outputs of 3.3, 5,
12, 15, 24, or 48V (see Table 1). Options C, T, X and Y also
offer one additional (28V) model (see Table 2).
When the input is cut off, the output is maintained for 20
milliseconds minimum. If the power supply shuts down due
to an output overvoltage condition, it is then necessary to
turn the unit off and wait approximately 30 seconds mini-
mum before turning the unit on again.
Specifications for each model of the HSF-PFC 50 Watt
Series are listed in Section III, on page 4 (standard models)
and Section IV, on page 6 (suffix C, T, X and Y).
OPTIONS.
Options are identified by suffix: T (-PFCT)
offers improved efficiency, less weight, and the addition of
a 28V, 50W model; C (-PFCC) offers current monitoring
via an integral current sensing resistor (includes option T),
X (-PFCX) offers remote on/off (includes option T); and Y
(-PFCY) includes options C, X and T.
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 remov-
ing unit from (or inserting into) rack adapter.
The front panel “MASTER ON” LED lights when 1) the unit
operates independently, or 2) the unit is used in parallel
redundant configurations while a) the output current is
within 10% to 100% of nominal and the unit is functioning
as a master or b) the output current is less than 10% of
nominal. In parallel redundant 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 or 2; test
points connected to the +S and –S lines are available at the
front panel for measuring the output voltage.
FORCED CURRENT SHARE CIRCUIT.
(Not avail-
able on 3.3V model.) When units are configured for N+1
parallel redundant operation, it is desirable for current to be
divided equally among the paralleled supplies. When the
CSB (Current Share Bus) lines of paralleled units are con-
nected together, the load current is forced to divide equally
between all paralleled units. 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.
