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Old 05-27-2019, 08:01 PM   #11
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[QUOTE=scfishnman;2104571]2018 Legacy SR340. Progressive EMS 50 indicates both lines at 122 to 123 volts but monitor panel inside RV showed 86 volts on one line and 107 on the other. Turned off fridge and both A/C units then turned off power switch in RV.

Rechecked voltage at shore power pedestal and then turned everything in RV back on. Voltages on both lines were good. About an hour later checked monitor panel and one line was below 100 volts. Pedestal still at 123 volts on L! and 123 volts on L2. Went through the same procedure again and after an hour or so brownout showed up again on RV monitor Panel.

Motor Home was purchased new a few weeks ago and has already had the Transfer Switch box replaced because of no shore power available in the RV.

I read through the existing posts, and thus far nobody has mentioned the possibility of BOTH sides of the 50 amp pedestal receptacle being wired to the same side of the supply. Check between both lines, and you should have a voltage on the order of 250 volts, or specifically line 1 plus line 2. If this checks out OK, my bet would be a bad neutral connection. This is a too common case with sloppy assembly (loose connections) and/or cheap connectors. The ones typically used by RV manufacturers are low end for a reason, although sufficient for the purpose, unless there's a problem with corrosion or a loose screw at a connection. Personally, I prefer Hubbell brand, as they will easily handle an overload if need be, and have really secure connections for stranded wire. A bit off topic...I would never use solid wire in a vehicle, as it invites failures down the road. I use marine cable, which is stranded, and the wires are tinned to resist corrosion. It is only costly once.

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Old 05-27-2019, 10:01 PM   #12
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I would start at the transfer switch. With all power off check the connections and look for signs of overheating. If there is heat being generated and you have a dissimilar metal at the connection (copper to aluminum for example) over time the connection could loosen up. just my 2Ę worth.

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Old 05-29-2019, 12:15 AM   #13
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Old 05-31-2019, 05:22 PM   #14
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Thanks for the suggestions. I have tried all ideas presented with no success. Forest River Tech support contractor and the dealer had no different ideas.

Connections are tight, no indications of anything charred, connections read the proper voltage at all points in the transfer switch. Storage facility owner has had electrician check all power pedestals which are new.

What I have learned is that brownout reading on the monitor in the coach (mine is the Precision Circuits Touch pad) will not change when the proper power returns unless the double 50 amp circuit breaker is cycled off/on OR the reading on the monitor touch screen is pressed. Then it reads the current power. In other words the Precision Plex touchscreen monitor continues to display the error until the monitor itself is reset. So, the brownout condition is a transient one. When I leave the coach in the storage facility, the rear A/C and the refrigerator are left on. When I return they are working but the monitor is reading brownout on one line. I have been checking every day with the same result.

I have the Progressive 50 Amp EMS at the shore power pedestal. It is supposed to shut down the line if a brownout occurs and then continue to provide an error code along with the "no error code" once proper power level returns. When the brownouts occur on my coach there is no error code reported on my Progressive 50 Amp EMS which makes me suspect that the problem is somewhere in the coach's electric system (could be the monitor reading or something more serious) rather than the storage facility's circuit.

To me the issue really is protection of appliances. I have not been able to determine if the coach EMS will shut down appliances when there is a brownout.

Anyone know if the Precision Plex control System in the coach shuts down appliance on a brownout line. I know it will shut them down in a priority order to avoid a system overload tripping a circuit breaker.
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Old 05-31-2019, 08:15 PM   #15
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Sounds like a transient voltage drop, since your line protection doesn't show a problem; probably due to there being a delay built in to avoid shutting you down when a very brief voltage drop occurs, such as when an A/C starts.

On the other hand, it seems to me that the PP monitor is not designed with "real world" conditions in mind, considering that it retains an error code "forever" even though the drop was apparently nearly instantaneous. I would personally worry more about sharp voltage spikes than temporary droops. And, I might suggest that nearly all modern electronics are built to run off a low voltage source, anywhere from 5 to 24 volts as a rule, and the power supplies almost invariably are designed to operate from line voltages from 100 to 240 volts without adjustments.
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Old 05-31-2019, 08:44 PM   #16
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Brownout in RV But Shore Power Pedestal at 123 v each line

Color me stupid, but I didnít see anywhere where you used a meter to check the voltage.

Unless Iím drunk the EMS measures in...not out. It has a contactor built in that can cause all the symptoms.

As stated a bad connection is most likely the issue. Where is the problem.

I know nothing about transfers so I am out there.

We need an engineer...he will be along directly.
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Old 06-01-2019, 05:01 AM   #17
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it is true that the EMS measures the input voltages and connections. it does not know what is going on after it passes power to the output side. the fact that it is not showing a prior error seems to indicate that it did not see a voltage drop of the magnitude being displayed on the power panel. of course if it was a transient it might have been of such a short duration that it did not have time to react.

i am not aware of how the power panel works. does it display the instantaneous voltage or does it 'freeze' and display a lowest voltage encountered since the last reset? also where is this power panel installed? is it in the shore line before the transfer switch or in the line from the output side of the transfer switch? this might help diagnosing where any potential loose connection is?
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Old 06-01-2019, 05:27 AM   #18
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Does the problem continue to appear if you run without the EMS? It does have its own contactor and would be nice to eliminate it totally as a source of problems. Besides, your pedestal seems to be stable.


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