ATF: Cyclone - AC Causing Power Inturruption

CabinetmakerII

Active Member
I have noticed that the factory installed roof mounted air conditioner unit causes a short 120VAC power interruption after running for a few (2/3) hours. I does not trip any breakers but all 120 volt circuits shut down for a couple of seconds then it restores itself. There is some audible "clicking" at the converter as the power is being restored. This power interruption is hard on the installed electronics and took out the HDMI input to our TV set. Is the converter going bad?
 

danemayer

Well-known member
Hi CabinetmakerII,

The power converter changes 110V AC into 12V DC and probably has nothing to do with what you're experiencing.

It does sound like the transfer switch (where shore power and generator power are switched) contactors are dropping.

Your 50 amp service has two legs (L1 and L2) coming off the pedestal and into the transfer switch. The transfer switch looks for 120V on L1 to activate the contactors (large relay) and complete the electrical path to the circuit breaker panel. If voltage drops to about 104V, the contactors will deactivate, dropping all 110V power into the coach.

The first thing to check is the power pedestal using a voltmeter. If you're not sure how to do this, or don't have a voltmeter, get help from the park's maintenance staff. Also check that your power cord is securely connected to the trailer. If a twist-lock, make sure it's fully locked.

If everything outside is ok, you may need to call a mobile tech or go to a dealer to have your transfer switch checked out.
 

CabinetmakerII

Active Member
We are currently connected to 30 Amp service... If the transfer switch is looking at L1 would that contribute to the problem? We have had this happen a few other times but I do not recall if we had 30 or 50 Amp service at the time...
 

danemayer

Well-known member
With 30 amp service, the pedestal has only one hot wire. The adapter from 30 to 50 takes the single wire and ties it to both wires of the 50. The transfer switch should still get full voltage from the pedestal to the L1 side of the switch.

A bad 30-50 adapter could be creating a problem.

Also, campgrounds that provide 30 amp only may have older electrical gear or limited power coming into the park. Your voltage at the pedestal could be marginal or might be fluctuating. If it's hot and the park is full, the possibility of voltage drops increases.

If you've had damage to appliances in the RV, you should take some voltage readings at several of your outlets.

Check voltage between Hot and Neutral, between Hot and Ground, and between Neutral and Ground. Ideally you should see 120V, 120V, 0V. If you see readings like 115V, 120V, 5V, you may have a problem with the neutral wiring at the pedestal, adapter, or somewhere inside the coach on the way to the outlets. Problems with neutral wiring need to be investigated to prevent damage to your appliances.
 

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