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

wa8yxm
Explorer III
Apr 02, 2015
bob213 wrote:
I will try the autoformer after the EMS.
But wouldn't that leave me vulnerable to a malfunction in the autoformer?

Autoformer malfunctions are fairly rare but .....

The autoformer is there to correct out-of spec voltage from the post.. IF it is doing anything beyond pass-through then putting the EMS in front of it may get you shut down due to low (or high)voltage (most likely low)

If the EMS cuts our at say 110 volts

And the delivered is 105

And the sequenceis

Post---Autoformer---EMS--_RV

You see 115V inside

But under those same conditions if the sequence is

Post--Ems--Autoformer---RV

You see noting inside cause you are (As you should be) Cut off!!!
CA_Traveler
Explorer III
Apr 02, 2015
Connect up using extension cords and 10+ amp draw. Enough to cause the autoformer to boost and see if you have the problem.
bob213
Explorer
Apr 02, 2015
Update...
After several days at home on 30amp each unit works fine independently. They also work fine together. Only had about a max. of 7 amp load on system but never had a fault code and never saw autoformer go into boost. Obviously, my home 30 amp isn't facing the draw that a campground would, but I have to believe that my problems were "pedestal" related.
We'll find out more next time out at a different campground.
bob213
Explorer
Mar 30, 2015
I was going to call PowerMaster (VC-30) tomorrow but can't seem to find them. Does anyone know if they are still in business?
bob213
Explorer
Mar 30, 2015
AllegroD........... please tell me what an ATS is so I can answer your question. I'm guessing "no" since I don't know what it is :)

I have 30amp at home. I will do solo checks this week and report my findings.
AllegroD
Nomad
Mar 30, 2015
bob213 wrote:
Connected as follows: 30amp Post,-PowerMaster autoformer,- PI EMS-30,-trailer.

The above works, if all equip is working as designed. You want the autoformer pre-PI EMS so the autoformer can boost voltage and the EMS only shuts it down when the autoformer cannot get voltage up. Been doing this way for years.

As other have said, it really sounds like a shore pole problem. Be interested in your testing om another source and with each device solo.

Do you also have an ATS?
bob213
Explorer
Mar 30, 2015
pianotuna wrote:
Hi,

Does it trip the 30 amp breaker without the autoformer? How about without the ems?

I left today so I did not try either of the options you ask about.
pianotuna
Nomad III
Mar 30, 2015
Hi,

Does it trip the 30 amp breaker without the autoformer? How about without the ems?
CA_Traveler
Explorer III
Mar 30, 2015
bob213 wrote:
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.
Wow incredible. No 30A load on the pedestal and it tripped with the addition of a 20A cord with no load?

The jury isn't out on this one - the pedestal has problems.

Now if you can reproduce the problem at another CG then there is more to the story. :@
CA_Traveler
Explorer III
Mar 30, 2015
bob213 wrote:
I will try the autoformer after the EMS.
But wouldn't that leave me vulnerable to a malfunction in the autoformer?
Of course but any more than a EMS failure? It's just a test after all.

Basically with the EMS first low voltage causes it to disconnect so that's not the best long term approach.

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Strange power problems with PI EMS 30 and autoformer?

18 Replies

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