14
HSF 600W 042315
4
LOAD CONNECTION
Connect the load to (+) and (–) terminals at the rear panel of the Rack Adapter (see RA 19-4C
Instruction Manual for details).
5
CONNECTING MULTIPLE POWER SUPPLIES
All connections to multiple HSF power supplies must be made via the I/O mating connectors at
rear of the Rack Adapter or by the Rack Adapter DIP switches. These connections, including the
configuration of the two internal HSF DIP switches, are described in the Rack Adapter Instruction
manual, and include:
•
Using one power supply to control the output of multiple supplies.
•
Using parallel master/slave configurations (for increased current or redundancy) where
the user either predetermines the master or allows the load to determine which is the
master. These configurations also cover the use of the Current Balancing feature of the
HSF power supply.
•
Using series configurations (for increased voltage).
•
Using open-on-fail or close-on-fail alarm schemes with multiple power supplies.
5.1
ADJUSTING THE VOLTAGE
NOTE: Refer to the RA 19-4C Rack Adapter manual for alternatives to the standard master/
slave parallel configuration described below.
To adjust the paralleled units, turn off all the units except one (designated as the master) and
adjust to desired voltage using the front page trimmer and monitoring the front panel voltmeter.
•
Each slave must be adjusted to a slightly lower voltage than the previous unit. The differ-
ence between the master and the lowest voltage slave must not exceed 2% of E
NOM
.
•
The voltage separation between master and subsequent slave(s) (V
SEP
) = 2% E
NOM
/ N
where N = number of units in parallel.
Adjust the first slave V
SLAVE1
to E
NOM
- V
SEP
. Adjust the second slave V
SLAVE2
to V
SLAVE1
- V
SEP
.
Adjust the third slave V
SLAVE3
to V
SLAVE2
- V
SEP
and so on.
As an example, for three HSF 24-27 units in parallel, 2% of E
NOM
is 0.48V and V
SEP
is 0.48/3 =
0.16V. Turn off the master, then turn on another unit (slave 1) and adjust for 160mV less than the
master. Turn off slave 1 and turn on slave 2 and adjust for 160mV less than slave 1.
When all units are turned on, the unit adjusted to the highest voltage will be the master. If a unit
fails, the VDC ON indicator of that unit is either off or red.
5.2
PARALLEL CONNECTIONS, STANDARD AND C MODELS
When using parallel-connected standard (no suffix) and C Models, a minimum load is required to
avoid the slave becoming “idle.” When the slave is idle, the output is off, no lights are lit, and the
alarm is set.
The minimum load (Amperes) = N x (I/10)
where N = the number of units in parallel,
I = Nominal current rating of individual power supply (Amperes).
