Correction.
With this new 120V relay installed, the Prog. Ind. EMS only works OK on shore power if there are no 120VAC loads in the trailer when it turns on. Otherwise, the Prog. Ind. EMS records an E7, Line Frequency High error.
But for the 2 minutes delay before the EMS turns power on, the EMS says the line freq is 60hz, and this never happened before installing the new 120V relay between the EMS and the 120VAC panel. So the error must come from some interaction with the relay.
And if I turn off the trailer's main circuit breaker before the EMS turns on, eliminating all loads, there is no problem. So that's my current solution.
Weird. Maybe arcing at the new relay's contacts when under load? Or ...?
I'll send an email off to Prog Ind and see if I get a response.
EDIT: another solution would be to re-wire the relay so shore power goes through the NC contacts.
