Carl Denk <cdenk <at> alltel.net> writes:

> Just to summarize symptom: Relay drops out, switching PLC from 120VAC > 
> 12 VDC switching supply to 2 lead acid batteries connected with diodes 
> to relay. Switches OK when 120 is from utility, PLC resets when 120 is 
> from generator. Switch over to 120 supply is OK with either utility or 
> generator source.
> 
> Did disconnect one battery at a time, no change. Did add house 
> electrical load, as opposed to just exercising generator with no 
> transfer, no change.
> 
> ??
> Replace relay - with what?
> Add capacitor to bridge during changeover - how big, where?
> While only with generator source?

Try to add serious filtering after the relay before the PLC. Corcom etc line
filter grounded at the PLC and with real earth. I suspect there is conducted
noise and/or a ground loop that is opened when the relay opens on the generator
side. Analyze your grounds and see what the relay does (not) separate. 

hope this helps,
Peter P.


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