KEPCO RA 19-4C Operator Manual - Manual (Page 26)

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RA 19-4C 121013
2.4.2 PARALLEL OPERATION
Up to four identical HSF Power Supplies can be connected in parallel (with or without N+1
redundancy). Connecting 300W models with 600W models of the same voltage, or 600W mod-
els with 1500W models of the same voltage in a parallel configuration is not recommended
because differently rated models will not current share. The impedance of the load wires
between each power supply and load should be the same. In addition, multiple RA 19-4C rack
adapters that are fully populated with identical HSF power supplies may be paralleled using
external wiring at the I/O connectors. When using HSF 300W and 600W models, the sense
lines MUST also be configured (see PAR. 2.4.2.5).
For a single remote ON-OFF signal to turn off all parallel-connected units, at the I/O mating con-
nectors connect together all +RC pins (pin 15) and connect together all –RC pins (pin 8).
Four things must be considered when configuring the rack adapter for parallel operation:
• VOLTAGE CONTROL
• DC OUTPUT
• CURRENT BALANCING
• SENSE CONNECTIONS (300W and 600W ONLY)
The power leads must be connected in parallel externally by connecting each power supply
directly to the load; DAISY CHAIN WIRING IS NOT PERMITTED, however bus bars are avail-
able as accessories to make these connections when paralleling adjacent slots (refer to Table
1-2).
Parallel-connected power supplies operate with one power supply as the master and the rest as
slaves. This can be done using either individual control or group control.
Individual Control. Individual control means that the output voltage of each must be indi-
vidually adjusted to within 2% of each other. The power supply with the highest voltage will be
the master and the rest will be slaves.
Group control. Group control means that the user designates one power supply as the
master, and the rest are slaves. Adjusting the output voltage of the master determines the out-
put voltage of the parallel-connected group.
For both individual control and group control, the power supplies can be adjusted either locally,
using the front panel adjustment control, or remotely, using either an external voltage or resis-
tance. Since multiple external voltage or resistance sources would be required for individual
control, individual control is usually by local (front panel) adjustment of each unit. For both indi-
vidual and group control, current balancing (also referred to as forced current sharing) is imple-
mented to equalize the load current (see PAR. 2.4.2.4).