Built in generator.

[Dam Worker]

This question is for those Montana owners with a built in generator. I have found out that the transfer switch in my unit switchs with a loud bang when switching to generator source from 12 volt DC. . Are any of you experiencing the same loud bang when the transfer switch actually switches? I have also traced the loud buzz/hum when on shore power to this transfer switch thanks to information I read on this site. It also got the on/off switch installed in the closet which is very inconvenient. Last but not least do those of you with gensets have vented access doors like I have on my Arctic Fox campers genset? Inside my Montana it starts to smell like hot plastic if I have the generator on for very long and the compartment gets very hot with just having a small ventilation hole in the floor of the generator compartment. It is hot enough that you don't want to touch anything inside the compartment.
On a positive not it seems to be fairly quiet.

Thanks in advance for sharing your information.

Tom Marty

[bncinwv]

What you are describing is how the on-board genny has been on our two genny equipped units. Transfer switch is for shore power versus genny, has nothing to do with 12V DC however. It is good practice to make sure the lugs inside the transfer switch are torqued properly. Ours does not smell like hot plastic however.
Bingo

[jcurtis934]

Don't have one and certainly wouldn't run one with door closed. My opinion only. John

[bncinwv]

quote:Originally posted by jcurtis934

Don't have one and certainly wouldn't run one with door closed. My opinion only. John

Actually, they are designed to be ran with the compartment door closed. This also helps to mute the sound of the engine running.
Bingo

[Dam Worker]

Bingo while I was camping, battery and generator only no shore power I would still get the loud bang when the transfer switch allowed 110 v power through the system. As for loud buzzing that only happens when I am hooked to shore power. I have not tried the generator while hooked to shore power to see if I get the same loud bang but I would imagine that I would as it is still switching to a different source. From what I could see it looks like your genset door is also not vented. Is your genset cover made of molded plastic or is it sheet metal?
Thanks.

Tom Marty

[Fire5er]

We do not have an on board generator. However, it has the generator prep and we also get the loud banging noise from the transfer switch when plugging into shore power, and the loud buzzing noise that the transfer switch makes when on shore power is annoying. In fact we are taking our Big Sky back to the dealer this weekend for some warranty work and we are going to have them look at the transfer switch to see if that noise is normal (many here say it is), if it is normal I will have them give me an estimate to have the switch bypassed.

[Mudchief]

On our unit there is no buzzing when on shore power or bang when it switches. I have the IOTA switch on ours maybe they are using a different model.

[Sniperduce]

no noticeable sound when running our on board unit while on shore power or not. I always run it with the generator compartment door closed unless I'm running it from the outside startup panel on the unit.

[bncinwv]

quote:Originally posted by Dam Worker

Bingo while I was camping, battery and generator only no shore power I would still get the loud bang when the transfer switch allowed 110 v power through the system. As for loud buzzing that only happens when I am hooked to shore power. I have not tried the generator while hooked to shore power to see if I get the same loud bang but I would imagine that I would as it is still switching to a different source. From what I could see it looks like your genset door is also not vented. Is your genset cover made of molded plastic or is it sheet metal?
Thanks.

Tom Marty

It is he same type door as all the other compartments, foam interior and a hard plastic type outer shell and a lighter inner shell. The only venting is through the bottom and it does get warm!

Bingo

[MHC305RL]

The loud bang will be the contactor pulling in to allow power from that source. There are 2 contactors in the transfer switch so you will hear the "bang" whether on shore power or generator. If you have a Progressive Industries EMS, you will hear the contactor close in it as well.

The humming is the coil holding in the contactor. Sometimes, coils get weak and they will hum or some dirt or arcing corrosion is on the contacts and that will create a hum as well. I would have them look at it and replace the contactor that is humming. That would get annoying.

[Dam Worker]

Thanks MHC305RL for the information. I work in a hydro eclectic plant and I am somewhat familiar with transfer switches and circuit breakers in general. Usually a lot bigger for higher voltage. :-). What is interesting is that my Arctic Fox camper transfer switch is able to switch without a loud bang. Usually the only thing you hear is a beeping noise to let you know that your unit has switched power sources. Some one else on here had a good explanation of the AC verse the DC windings and the difference between loud buzzing AC style and almost no buzzing using the DC style transfer switch.
I will ask the service department about it as I need to take it back in to finish the warrantee work and to get the front cap fixed where they ran into it with a forklift mast.:-(

[Phil P]

Hi

I see from this post that some have the “hum” and some don’t. I have worked with transfer switches in the past and when they are wired correctly there is not any power to the contactor coil when the switch is in the normal or shore power position. The coil is energized when the auxiliary power is supplied by the generator. The noise from the generator would keep you from hearing the hum when the generator is in service.

I would assume if you hear a hum on shore power that your transfer switch is wire incorrectly.

Phil P

[Dam Worker]

Phil I have asked the service department to at least look at it. The wiring concept is quite interesting. I will have to check up on that idea..

Tom Marty

[kylec2]

Our rig has an internal generator. You hear the transfer switch engage when connecting shore power and again when operating the generator. In either case the noise is a slight "thump" and there is no humming coming from the switch.

[Phil P]

Hi

The transfer switches I have used in the past were spring loaded in the normal service position or in the case of an RV in the shore power position. There should be no switch operation when applying shore power.

I have been intending to install a front shore power receptacle on our trailer and that would use the transfer switch. When I get around to it I will see how these transfer switches work. I would think it would cost more to have 2 Ac circuits to operate the switch in both directions instead of holding in the shore power position with springs.

Phil P