KEPCO RA 19-4C Operator Manual - Manual (Page 32)

2-14
RA 19-4C 121013
2.4.2.4 CURRENT BALANCING
NOTE: For HSF 300W and 600W models, refer to associated power supply Operator Manual
for minimum load or output voltage limits needed to avoid “slave idle” or output oscilla-
tion (when slave is idle, output is off, no lights are lit, and alarm is set).
The current equalization with up to four HSF 300W, 600W, 1200W or1500W units in parallel
should be within 20 to 90% of the total output current rating. The output voltage of any Power
Supply individually must be within 2% maximum of the other power supply output voltage set-
ting. The expected current sharing is such that the output current variation for each power sup-
ply is less than or equal to 10% of each power supply rated output current.
N+1 Redundancy. An N+1 system requires one additional power supply than necessary to sup-
ply the load. If one of the parallel-connected units fail, the others will continue to provide power
to the load without down time.
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 CB (Current Balancing) lines of paral-
leled HSF units are connected 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 auto-
matically isolated from the circuit by a built-in isolation diode.
For parallel operation (see Figures 2-7 or 2-6) the conditions for current equalization are:
variation of output voltage in each power supply
The maximum output current: Rated output current of each power supply x (number of power
supplies) x (20 to 90 percent).
Variation of output current < ±10 % of each rated output current
To control the output from a single power supply without adjusting each one individually to
within 2%, refer to PAR. 2.4.2.3 and Figure 2-7.
2.4.2.5 SENSE CONNECTIONS FOR PARALLEL CONFIGURATIONS (HSF 300W AND 600W
MODULES ONLY)
NOTE: HSF 300W and 600W power supply sense lines MUST be connected to the respective
output terminals; otherwise the power supplies will not work.
For parallel configurations the sense lines must be connected in parallel. This can be accom-
plished either by using the DIP switches (positions 3 and 4 set to ON) or by setting the DIP
switch positions 3 and 4 to OFF and using external wires. When configuring units to work in par-
allel, the current share bus (PAR. 2.4.2.4) must also be configured.
For local sensing (at the rack adapter) connect the sense lines in parallel using either the DIP
switches or external wires, then connect one +S and one –S from the I/O mating connector to
the (+) and (-) Output terminals or the corresponding terminals on the bus bars (see Table 1-2)
using short jumpers.
For remote sensing (at the load) connect the sense lines in parallel using either the DIP
switches or external jumpers to connect the sense lines in parallel, then connect one +S and
one –S from the I/O connector to the load using external wires.
Maximum Voltage Minimum Voltage –
Rated Voltage
------------------------------------------------------------------------------------------------ 2% =