16
HSF(A) 600W 040215
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 (A, AM) power supplies must be made via the I/O mating connec-
tors at rear of the Rack Adapter or by the Rack Adapter DIP switches. These connections, includ-
ing the configuration of the two internal HSF (A, AM) 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 (A, AM) power supply.
•
Using series configurations (for increased voltage).
•
Using open-on-fail or close-on-fail alarm schemes with multiple power supplies.
NOTES: 1. To enable current share, the difference between voltage settings of parallel con-
nected units should be less than 0.5% of the nominal voltage value of the units.
Output voltage adjustment should be done at same load for each unit.
2. An overshoot of about 1% of nominal voltage occurs upon power up of each unit.
When powering up with no load, overshoot may last up to 15 seconds and alarm
may be temporarily triggered on one of the other parallel-connected units.
3. Load effect specifications will not be met when units are operated in redundant
mode with load less than 10% per unit.
4.
Minimum Load.
A minimum load is required to operation without voltage set
restrictions (see Note 5, below). The minimum load is defined as:
minimum load (Amperes) = N x (
I
/10)
where N = the number of units in parallel,
I
= Nominal current rating of individual power supply (Amperes).
5.
Voltage Set Restrictions.
When units are at light load (under 10% of nominal),
and voltage settings are less than 80% of nominal, voltage set restriction are
required. To avoid a “slave idle” condition (PF signal set, red ALARM indicator on)
the output voltage of all parallel-connected units must be set within 0.5% of each
other and be at least 80% of their nominal (rated) output voltage (90% for 48V
model).
