Transfer Switch Contactors

Ron,
Contactors have a rrating for both the contacts and the coil.
In your case,the contacts can be 240volts 50amps.
The coil 120 volts most likely.
As stated above some may have D.C. Coil to eliminate humming.

If your switch has only one contactor, it is normally de-energized when connected to shore power and engerized when the generator is running. Any contactor can have both mechanical problems as well as electrical issues.

I think you would be best served to replace the whole switch

Consider getting the top dog 100 amp rated.

http://www.bestconverter.com/100-Amp-Transfer-Switch_c_195.html

I put this one in mine two years ago:https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=PMTS-50+Power+Max+50+Amp+Transfer+Switch&rh=i%3Aaps%2Ck%3APMTS-50+Power+Max+50+Amp+Transfer+Switch
Works just great. Alvin

lanerd wrote:
Just as an update, I've decided to bite the bullet and just replace the entire transfer switch. Sorry to put everyone through all my questions.

Thanks to all...

Ron

Probably the best idea. Get it from these guys, they are known for great service and helping folks here.
Bestconverter

Just as an update, I've decided to bite the bullet and just replace the entire transfer switch. Sorry to put everyone through all my questions.

Thanks to all...

Ron

lanerd wrote:

D.E.Bishop wrote:
lanert, wouldn't the amperage rating be more important. Most relay contacts are rated in amps, the relay coils are rated in volts. So you probably need 120vac relays with 60 amp or better contacts.

But the relays are rated at 50 amps in either 120v or 240v....no amperage is specified. Plus amperage is applied with the load, so initial connection would be almost 0 amps....only after you start turning things on will there be current draw. If the relay is rated for 50 amps (max in our motorhomes), either relay (120 or 240) should work.

Since using either 15 amp, 30 amp or 50 amp services.....all are 120v. That tells me that any voltage over it's rated capacity, the relay will fail. So if I have a 240 v relay and I only apply 120 volts to it, I would think it would work just fine. So far I haven't found or heard where it won't.

My problem is that I can purchase a 240v relay but can't find a 120v anywhere. So my question is can I use a 240v relay?

Ron

You must have missed my other post. This Link will take you to a 120V 50A transfer relay. Works well and has very good reviews.

ON further inspection, I've noticed that the center section (like a push-button circuit breaker will depress when power is applied and will pop back out when power is removed. Is this normal operation of the relay? I'm thinking about starting the generator and see if that relay does the same thing.

Yes that is the energized coil pulling the contacts together

quit worrying about voltage rating
You can use a motor contactor rated at 220v
But it must have the correct coil voltage
In this case 120v coil
Many motor contractors used in machinery have 24v coils
You can not use one with a 24v coil
Your replacement must have a 120v coil
If you buy from an RV supplier, likely no problem
If you are searching on line for the best deal
You need to pay attention to the coil voltage and the physical size
Or it may not fit

lanerd wrote:

D.E.Bishop wrote:
lanert, wouldn't the amperage rating be more important. Most relay contacts are rated in amps, the relay coils are rated in volts. So you probably need 120vac relays with 60 amp or better contacts.

But the relays are rated at 50 amps in either 120v or 240v....no amperage is specified. Plus amperage is applied with the load, so initial connection would be almost 0 amps....only after you start turning things on will there be current draw. If the relay is rated for 50 amps (max in our motorhomes), either relay (120 or 240) should work.

Since using either 15 amp, 30 amp or 50 amp services.....all are 120v. That tells me that any voltage over it's rated capacity, the relay will fail. So if I have a 240 v relay and I only apply 120 volts to it, I would think it would work just fine. So far I haven't found or heard where it won't.

My problem is that I can purchase a 240v relay but can't find a 120v anywhere. So my question is can I use a 240v relay?

Ron

Where and Why do you think there will be NO LOAD???? IF you have the roof AC's on and other appliances. THAT Load(about 35 to 50 amps) will be causing the contac points to arc when the appropriate relay opens or closes. THAT is what causes Transfer Boxes to fail(usually). Doug

lanerd wrote:


But the relays are rated at 50 amps in either 120v or 240v....no amperage is specified. Plus amperage is applied with the load, so initial connection would be almost 0 amps....only after you start turning things on will there be current draw. If the relay is rated for 50 amps (max in our motorhomes), either relay (120 or 240) should work.

Since using either 15 amp, 30 amp or 50 amp services.....all are 120v. That tells me that any voltage over it's rated capacity, the relay will fail. So if I have a 240 v relay and I only apply 120 volts to it, I would think it would work just fine. So far I haven't found or heard where it won't.

My problem is that I can purchase a 240v relay but can't find a 120v anywhere. So my question is can I use a 240v relay?

Ron

You very much can have 240V RMS applied to a set of relay contacts on a 50A RV even if nothing in the RV is operating at 240V. You have a 240V supply (well, a 120/240V split phase supply). Should the neutral connection open first, whichever hot opens next will have the full 240V line voltage across it. (Of course, what that voltage is depends on the timing of the contact opening with respect to the AC cycle timing; it could be anything from 0V to about 340V, the peak voltage.)

In short, the contacts should be rated for 240V RMS minimum. There is no problem with using 240V contacts on a 120V circuit; the voltage ratings are maximums. It would also work equally as well on, say, a 24 VAC circuit. (DC circuits are somewhat of a different matter because the DC waveform doesn't periodically cross zero volts, which means that arcs when the contacts open continue longer rather than breaking down when the voltage crosses zero.)