Sorry for the length of this but details help:This is not a first outing with these items.Connected as follows: 30amp Post,-PowerMaster autoformer,- PI EMS-30,-trailer. Post had 50amp/30amp/20amp breakers. 30amp checked out fine with hand held checker and open ground detector. EMS ran check and turned on without problem.Plugged extension cord into 20amp outlet and turned on breaker. This caused an over current situation on the 30amp breaker and EMS shut down. Turned off 20amp breaker and EMS reset.Later that evening, with the refrig on electric, the coffee pot, two 12 volt lights, television and satellite box on, I turned on 1 more 12 volt light. EMS shut down everything and showed an "open ground" fault. Reset EMS and it recycled and returned power without a problem.Any ideas on what would cause this? I turned on the same 12 volt light without problem after the reset. Do I just have a sensitive unit? Is this something you have to live with to have EMS protection?When only using the autoformer we never experienced these problems. I may have been having problems and just didn't realize it.Thoughts please....

Perhaps the Autoformer and EMS don't play well together. You should pursue that issue with PI first, may be the end of the problem. If not, there will be folks here that will have a handle on the situation.Vic

is your EMS surge only protection or low voltage protectionwhy not but the EMS before the auto transformerand see if it works better that waythe auto transformer has a relay or stepper to change contacts/windingsthis switching time, is most likely when the EMS fault is occurringputting the EMS before the transformer will fix that possible cause

Good points above. It's also possible that this CG has lower voltage which is causing the autoformer to boost more often which effects the EMS. Any time you switch power (autoformer boost for example) electrical transients are created. These can cause unexpected results. Try another pedestal/CG or even a 25' 30A extension between the two units. And call both companies.And voltmeter readings might shed more information on the problem.

If the extension cord was plugged into the pedestal 20A and tripped the pedestal 30A then this sounds like a pedestal problem. I guess one should assume you had some kind on load on the extension cord when you flipped on the breaker?

Strange power problems with PI EMS 30 and autoformer?

18 Replies

bob213
Explorer
Mar 30, 2015
CA Traveler wrote:
If the extension cord was plugged into the pedestal 20A and tripped the pedestal 30A then this sounds like a pedestal problem. I guess one should assume you had some kind on load on the extension cord when you flipped on the breaker?

Actually the extension cord was not hooked to anything when I flipped the pedestal breaker. I agree that that part of my problem was probably pedestal related although I could not duplicate the surge with my meter hooked up. But then again, at that time there was no load on the 30amp either.
bob213
Explorer
Mar 30, 2015
I will try the autoformer after the EMS.
But wouldn't that leave me vulnerable to a malfunction in the autoformer?
bob213
Explorer
Mar 30, 2015
pianotuna wrote:
why plug into the 20 amp?

The 20amp was used for an extension cord for other purposes totally separate from anything to do with the trailer. It's just when I flipped the breaker for the 20amp I got a surge across the two circuits (it would seem, anyway).
CA_Traveler
Explorer III
Mar 29, 2015
If the extension cord was plugged into the pedestal 20A and tripped the pedestal 30A then this sounds like a pedestal problem. I guess one should assume you had some kind on load on the extension cord when you flipped on the breaker?
CA_Traveler
Explorer III
Mar 29, 2015
Good points above. It's also possible that this CG has lower voltage which is causing the autoformer to boost more often which effects the EMS.

Any time you switch power (autoformer boost for example) electrical transients are created. These can cause unexpected results.

Try another pedestal/CG or even a 25' 30A extension between the two units. And call both companies.

And voltmeter readings might shed more information on the problem.
MrWizard
Moderator
Mar 29, 2015
is your EMS surge only protection or low voltage protection
why not but the EMS before the auto transformer
and see if it works better that way

the auto transformer has a relay or stepper to change contacts/windings
this switching time, is most likely when the EMS fault is occurring

putting the EMS before the transformer will fix that possible cause
pianotuna
Nomad III
Mar 29, 2015
why plug into the 20 amp?
vic46
Explorer
Mar 29, 2015
Perhaps the Autoformer and EMS don't play well together. You should pursue that issue with PI first, may be the end of the problem. If not, there will be folks here that will have a handle on the situation.
Vic

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Strange power problems with PI EMS 30 and autoformer?

18 Replies

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