KEPCO, INC.
131-38 SANFORD AVENUE
FLUSHING, NY. 11355 U.S.A.
TEL (718) 461-7000
FAX (718) 767-1102
http://www.kepcopower.com
email: [email protected]
083013
228-1533 REV 15
3
CONNECTIONS:
The 24-pin I/O connector is designed
to mate with the corresponding connector in the Series RA
19-(X)B Rack Adapter. (See Rack Adapter manual for pin
assignments.)
(+) SENSE, (–) SENSE:
These lines are provided to compen-
sate for voltage drops in the load connecting wires. The
Sense lines must be connected to their respective (+)
and (–) output terminals,
either at the load or at the rack
adapter (see Rack Adapter Manual). The connection
ensures the most accurate error tracking. Maximum volt-
age drop compensation in the load connecting wires for
each model is calculated as the difference between the
minimum overvoltage (see Table 1 or 2) and the maximum
adjustment range (see Table 1 or 2), divided by two to give
the voltage drop compensation per lead. Higher compen-
sation values are possible if output voltage is decreased
below the maximum adjustment range shown in Table 1 or
2.
NOTE:
The Sense lines must be connected for
the power supply to work properly!
OUTPUT (+), OUTPUT (–):
These lines are the power supply
d-c output lines which are connected to the load.
CURRENT SHARE BUS (CSB):
(Not available on 3.3V
model.) Connecting the CSB lines of power supplies oper-
ating in a parallel configuration causes output current to be
shared equally. (See Rack Adapter Manual for additional
information on parallel configurations.). For current sharing
to work properly the outputs of all paralleled units must be
within 250 mV (max) of each other and each unit must be
operating at between 10% to 100% of rated output current.
If current to the load goes below 10% for each unit in cur-
rent share mode, all MASTER ON lights may go on (see
load effect specifications); this indicates that forced current
share is no longer working, units are simply in automatic
current share mode. (If forced current sharing at less than
10% nominal current per supply is needed, contact Kepco
application engineering.) Remote sensing is recom-
mended. For master/slave operation to work properly each
unit should be adjusted to 40 mV (optimum) less than the
next paralleled unit. Unit 1 is adjusted to V
OUT
, unit 2 to
V
OUT
– 40mV, and unit 3 to V
OUT
– 80mV, etc. If the master
fails, the unit 2 will become the new master. The 40 mV dif-
ference can be reduced to a minimum of 25 mV as needed
to parallel many units and still keep all units within 250 mV
of each other. Adjust the outputs using Vadj trimmer on
front panel.
• Optimum difference among output voltages of par-
alleled units: 40mV
• Maximum difference among output voltages of
paralleled units: 250 mV
• Minimum difference among output voltages of par-
alleled units: 25 mV
ALARM:
The Alarm NC (normally closed) - Open on Fail-
ure and Alarm NO (normally open) - Close on Failure lines
are relay contacts referenced to Alarm Common. If the unit
fails, the path between Alarm NC - Open on Failure and
Alarm Common opens, the path between Alarm NO - Close
on Fail and Alarm Common is a short circuit. Figure 3 illus-
trates typical Close on Fail and Open on Fail circuits to give
a failure indication if any one of a number of power supplies
fail. See RA 19-(X)B Manual for limitations applicable to C,
X and Y suffix models described in “Alarm Circuit.” on
page 2.
INPUT POWER:
Line (either a-c or d-c source power), Neu-
tral and Ground (chassis)
FIGURE 3. TYPICAL ALARM CIRCUIT DIAGRAMS
