Voltage variations and Surge cut off.

Unless you have a (malfunctioning if automatic) autoformer, you aren't gaining voltage. Wires simply don't do that. It's entirely possible that the EMS's voltage readout calibration and your meter's calibration are out of whack with each other; as to which one is correct if either, you'd have to check against something with a known correct calibration to know.

It appears that you have a slightly resistive neutral connection somewhere, and the power imbalance caused by the air conditioner is causing it to track that leg a little and so give an unbalanced voltage. Cleaning the plug and making sure it's well seated in the socket would be a reasonable first step to try to correct it. Failing that, it's a matter of chasing down where the problem is, whether in your RV's wiring or the campgrounds, and hopefully getting it corrected.

What are the readings when you turn off 'kill power'to the inverter/converter
Also why is every thing on leg2
What is on leg 1 ?
Perhaps water heater should be swapped to leg 1 our swap inverter/converter to leg 1
Your system is out of balance,

joelc wrote:
We are hooked up to 50A service. I just recorded the voltages at different areas and I will note them below. I have a Progressive EMS/Surge suppressor hard wired in just before the breaker box. It has always worked well and has saved the coach several times at CG. My problem is it seems, there is a voltage rise on one leg at night, about 3 a.m. and when the heat pump goes on the EMS cuts the current. Both legs are high, but one is about 130V.

Taken 11 A.M. today
1. Voltage at post. Both legs 121 V
2. Inside at input to EMS Leg 1 = 128V 0 A Leg 2. 127 V 0 A
This simply cannot be accurate unless as Drew suggested you have a autoformer. Or of course one or both meters are no longer accurate.

The A/C voltage does drop during the day with no problems. If I shut off the electric water heater, there are no problems running the heat pump on heat during the night.
What PE error does the PI display? Your A/C or heat pump draws 18A per your post. Add 15A for hot water and that 33A on a 50A circuit. Well within 50A capability.

50A Basics: A 50A circuit is very dependent on a good neutral in order to keep the 2 legs at nominal voltages. Clean your plug and check all connections to and including the PI unit. It could be the CG and one way to confirm that is move to another CG as CG management usually assume your rig has a problem.

It is possible you have an Autoformer or other device however there is possibly a more simple solution.. I assume your EMS "inside" is a load control, (Intelletec) Not a protection device (Progressive Industries).. But in truth this does not matter.

Were you useing the SAME volt meter for all tests or were you reading the display on the EMS?

The simpliest explanation may be "Different meters often do not agree".

OP,

Maybe this will help: Assume 120/240V utility power and a marginal CG or rig neutral. You could see for example 140V on leg 1 and 100V on leg 2. The PI will disconnect on one or the other and show a related PE.

Maybe a loose neutral line. :)

Bad neutral will not increase voltage on both lines.

We had a somewhat similar problem while camping in the Black Hills. Over the course of a 24 hour period I observed readings on the voltage display of our Progressive EMS that varied between 114v and 130v. The problem turned out to be a bad neutral connection in the post.

I did some measurements this morning again. I think I noted that for some reason the voltage is lower in the morning. But anyway here is what I got:
Voltage at the EMS
Before Both l1 and l2 121 V with 244 across
After the EMS. L1 and L2 121 V with 244V across
The reading on the LED was L1 128 and L2 127

The voltage at the circuit breaker box was 121V on each circuit with 244V across

This leads me to think that the LED display on the EMS is giving false voltages. I do not know if the display has something to do with cutting off the power or not. So I removed it and am still getting all same voltages.
I have a call into Progressive to find out additional information. If the problem occurs next time the heat goes on, ( I tested it and it was OK) then I will switch over to 30A until I get the problem resolved. No problems with 30 A.

joelc wrote:
This leads me to think that the LED display on the EMS is giving false voltages.

I read your original post several times and didn't quite understand your concern until you posted the above which indicates you're questioning the accuracy of your EMS's monitor panel readout, not it's ability to accurately connect or disconnect to power. Since you originally referred to your unit as being "hardwired" into your rig I'll therefore assume what you have is a Progressive Industries EMS-HW50C, essentially the same as my own EMS-HW30C. If so, open the EMS and you'll likely find a couple of trim pots similar to the single trim pot I have in my 30 amp version ...



Yours being a 50 amp may have 2 of these trim pots. This trim pot adjusts the voltage readout on the monitor panel but does not affect low voltage or high voltage cutoff thresholds. I trimmed my own against a known calibrated DVM but it's a bit of a guess since the EMS's readout only reads to full volts, not tenths. That said, I did manage to get mine to track quite closely to my calibrated DVM. All this said, it's hard to believe your EMS could be reading as far off as you claim - a volt or two I can see but anything more than that I'd wonder why.

A series of 10 pics of my own EMS-HW30C starts here.