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Rockwell Automation Publication 1606-RM055B-EN-P - February 2017
Basic Power Supply 5 A
This power supply is resistant and does not show malfunctioning when a load
feeds back voltage to the power supply. It does not matter whether the power
supply is on or off.
The maximum allowed feed-back-voltage is 35V DC. The absorbing energy
can be calculated according to the built-in large sized output capacitor that is
specified in
External Input Protection
The unit is tested and approved for branch circuits up to 30 A (UL) and 32 A
(IEC). An external protection is only required if the supplying branch has an
ampacity greater than this. Check also local codes and local requirements. In
some countries local regulations might apply.
If an external fuse is necessary or utilized, minimum requirements need to be
considered to avoid nuisance tripping of the circuit breaker. A minimum value
of 10 A, B-characteristic or 6 A, C-characteristic breaker should be used.
Parallel Use to Increase Output Power
Do not use the power supply in parallel to increase the output power.
Parallel Use for Redundancy
Power supplies can be paralleled for redundancy to gain higher system
availability. Redundant systems require a certain amount of extra power to
support the load in case one power supply unit fails. The simplest way is to put
two power supplies in parallel. This is called a 1+1 redundancy. In case one
power supply unit fails, the other one is automatically able to support the load
current without any interruption.
This simple way to build a redundant system does not cover failures such as an
internal short circuit in the secondary side of the power supply. In such a case,
the defect unit becomes a load for the other power supplies and the output
voltage cannot be maintained any more. This can only be avoided by utilizing
decoupling diodes that are included in the redundancy module.
Recommendations for building redundant power systems:
– Use the DC-OK signal contact to monitor the individual power
supply units.
– Use separate input fuses for each power supply.
– Use separate mains systems for each power supply whenever it is
possible.
– It is desirable to set the output voltages of all units to the same value
(± 100 mV) or leave it at the factory setting.
