Parallel Connection For Redundancy - Siemens SITOP PSU100S Operating Instructions Manual

Applications

9.2 Parallel connection for redundancy

NOTICE
Protective circuit for the parallel connection of more than two power supplies
For connection of more than two power supplies in parallel, additional measures must be
taken to prevent high backward feeding currents in the event of a secondary device fault.
For this purpose, a suitable protective circuit (e.g. decoupling diode or DC-conform circuit-
breaker) must be installed between each "+" terminal of the power supply and the common
connection point.
9.2 Parallel connection for redundancy
Connecting several SITOP PSU100S power supplies in parallel for redundancy purposes is
required if especially high demands are placed regarding the availability of a reliable 24 V
power supply.
Using the SITOP PSE202U redundancy module, two 24 V power supplies of the same type
up to 20 A can be decoupled (Figure 9-2 Redundant configuration with two power supplies
and SITOP PSE202U redundancy module (Page 62)). When one of the devices fails, then
the other automatically takes over the power supply. If one of the power supplies fails, then
this is signaled using an LED on the redundancy module as well as an isolated relay contact.
When dimensioning the system, it must be ensured that n+1 redundant connected power
supplies can handle the total power requirement of the remaining n power supplies.
Note
For a high reliability of the supply, it is recommended that the redundant switched power
supplies are fused separately on the line-side and, if possible, be connected to different
power supply networks.
Figure 9-2
You can find additional information at:
SITOP PSE202U manual (http://support.automation.siemens.com/WW/view/en/42248598)
62
Redundant configuration with two power supplies and SITOP PSE202U redundancy
module
Operating Instructions, 02.2013, C98130-A7589-A1-3-7629
SITOP PSU100S