Community Forums

Topman · 07-12-2012, 03:32 PM

I have a bit of a problem when I try to operate the roof air cond. This is the first opportunity I have had to do any testing since we purchased the coach.
When I first turn on the air conditioner, it runs fine for about 5 minutes and then the transfer switch cuts power to the coach. I am plugged into a dedicated 30 amp RV circuit at my shop.
On this coach, the inverter charges the batteries whenever there is AC power to the coach so the charger is operating at the same time although it is in the float stage.
I also noticed the same thing happening when I tried to test the heat pump last winter. I think the transfer switch is an "ESCO" or something like that.
Any thoughts?? Thanks, Iver.

Robi.1014 · 07-12-2012, 05:29 PM

You didn't say it, but I'm assuming that after the transfer switch "opens" (and the A/C shuts down ... along with everything else in the coach), the transfer switch re-engages and applies power to the rig.

The solenoid-portion of transfer switch draws its juice from the incoming power. I'd suggest measuring the 120VAC voltage at the input to the transfer switch to see if you are experiencing a voltage drop....perhaps dropping so much that the transfer switch actually drops out (i.e., opens up). Then with the load removed, the transfer switch re-energizes.

Topman · 07-12-2012, 10:55 PM

Yes, that is exactly what happens.
The transfer switch does re-engage for about 15 seconds and then off again and the cycle continues.
Tomorrow I will try the genset and a different power source and check it again.
Thanks, Iver.

wa8yxm · 07-13-2012, 09:37 AM

Transfer switch should not do that. It only cares if the Generator is operating (All of them) or with some makes if shore power is present)

Short bit on the differences:

Some transfer switches (mine for example) the "Resting" state (no power) is "SHORE CONNECTED"

Some the resting state is Disconnected This type normally take a second or two to connect shore power once you plug in.

ALL will default to the generator if it is running.

Transfer switches do not measure current and so long as it is less than their rating (Actually most can handle much more than their rating) should not respond to current.

EMS systems may respond to current
Power Guards like the Progressive Dynamic Surge Guards respond to VOLTAGE (not current)

IT is possible, that you have an excessively long power run to the outlet and as a result voltage is dropping.

IF your transfer switch is the kind that responds to shore power then the voltage could be getting low enough to cause it to drop out. but I'd be surprised, Takes only a fraction of the power to hold a relay that it takes to pull it in.

I'm guessing you have some other problem there. Or another device you are not telling us about.

Steve Ownby · 07-13-2012, 11:23 AM

Over,

The Esco transfer switch used in the Sig has a small power circuit protection devise mounted on the back side. It can be pretty hard to see in the typical mounted location. If you can position yourself where you can see this small box, there is a green light on the front if all is well. You might check & see if your light is green. You might be having a problem with one leg of your power when under load and the A/C puts you over this load threshold.

RickO · 07-13-2012, 11:54 AM

So can we assume that the AC has never worked using your current set up to the 30 amp circuit you're using?

How much current are you drawing for the few minutes it's working?

Rick

Topman · 07-13-2012, 03:30 PM

Okay I did some further testing.
The transfer switch does have a 105v cutout relay. It waits until the voltage from either the genset or shorepower have 105 volts and then it energizes.
The plug in my shop is 111 volts and inside the coach the voltage is approximately 110.6 volts.
I do have the surge suppressor box which has 2 green lights which are illuminated.
So can running one air conditioner as well as the battery charger (which is always on), drop the voltage enough to trip the transfer switch?
Previous owner said all A/C's worked fine. This is my first time to test them.
Thanks, Iver.

Topman · 07-13-2012, 10:32 PM

I moved the coach outside and started the genset.
I turned on the A/C and ran it for around a half an hour with no problems.
So it would seem our domestic voltage is either too low or the transfer switch is cutting out at a higher voltage than advertised.
I will keep investigating....
Thanks for all the responses,
Iver.