16
Rockwell Automation Publication 1606-RM056A-EN-P - December 2016
Basic Power Supply 10 A
Back Feeding Loads
Loads such as decelerating motors and inductors can feed voltage back to the
power supply. This feature is also called return voltage immunity or resistance
against Back- E.M.F. (Electro Magnetic Force).
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
Output on page 10
.
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 can 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 10A B-characteristic or 6A 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.
Please note: 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 can not be maintained any more. This can only
be avoided by utilizing decoupling diodes that are included in the redundancy
module.