Hummmm

Rodbuster

Well-known member
I have only owned this 5th wheel for about 6 weeks so I'm not really sure if this humming sound has always been there or not. I just noticed it yesterday.

I crawled into the basement and removed a panel. At first I thought it was my converter but then I noticed another metal box next to it. It is a little smaller than a shoe box and is marked
"Automatic Transfer Relay Switch" (model # PD52).
It is this box that the hummimg is coming from. Do I have a problem or is this humming sound normal?

By the way, what does this "automatic transfer relay switch" do?
It's in a 2012 Heartland Landmark

Thank you for any help.
Rodbuster
 

branson4020

Icantre Member
Your rig either has a generator or factory generator-prep. The auto transfer switch is required to make sure that you can never have both the generator and shore power conected at the same time.
 

porthole

Retired
Your Auto transfer relay will allow you to be connected to both shore power and your generator all the time. But, the generator has priority (at least in the Cyclone).
With the Genny off, the power flows through the relay to the breaker panel.
If you start the Genny, after a brief warmup the transfer relay will automatically switch from shore power to Genny and you do not have to unplug the shore power.
The hum is normal and a byproduct of having the circuits constantly monitored.
 

Rodbuster

Well-known member
I thank you for your replies. That's one less thing that I have to worry about.

By the way, no generator but yes, I do have the factory generator prep.
I'm sure learning alot from this forum.

Thanks again
Rodbuster
 
I have a 3600RL Bighorn - 2011 (full-timer since 1997). Same loud HUMMMM. I have 3 solar panels and 3000watt inverter going thru the transfer switch (PD52). Got tired of the HUMMMM so I removed the transfer switch (points REALLY worn after only 1 1/2 years!). When I use the generator (boondocking) I run a cord from generator to shore power plug-in. When useing inverter (boondocking) I go to a 30AMP breaker added to the breaker panel. So, normal shore power mode - 50AMP (main) breaker on, 30AMP (inverter) breaker off (my inverter doesn't like backfeed). Boondocking mode - 50AMP (main) breaker off, 30AMP (inverter) on, and converter breaker off. Generator mode - same as normal mode. It sure is nice not to have that HUMMMM!!
 
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