Siemens PSU300B Manual page 66

Applications
9.1 Parallel connection to increase power rating
NOTICE
Protective circuit for the parallel connection of more than two power supplies
When connecting 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.
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SITOP PSU300M/300B
Manual, 11.2014, C98130-A7574-A2-2-7629