Redundant power supplies failing when hot-swap


Thread Starter

Tomeu Gamundi

We have an industrial redundant power supply system based in SMPS. We have the capability to hot-swap or change one of the SMPS without losing power in system. Thus, one SMPS can supply the entire system.

The problem is that often (not always) when plugging in the second SMPS, we have a power fail in the bus power.

Three considerations:
1) The + of the two SMPS in connected to + of the bus with diodes, and the diodes are OK.
2) the - of the two SMPS are common.
3) We plug in the second SMPS without Line and switched off.

It seems that when connect the second SMPS we'll comrrupt the bus power and we've a power fail signal.

Anyone can help me to understand this problem or have experience in this topic?

One more thing! We don't have ground and negative of the SMPS connected. Our signal ground always are isolated from any kind of Power signal.

Thanks in advance.