Transfer Switch Contactors

The contactor is labeled "Chint NC1-5011" and does not have the voltage labeled on it. It does indeed have three connections ( 2 each hot, 1 neutral). Since there is nothing in the motor home that uses 220/240v, I would assume that the contactor should be rated only for 110/120v. When looking at these on Amazon, they look identical and are the same price but only the 220v is available. Does it really make a difference which one is used? I could see not using a 110v unit on a 220v system, but I don't see where using a 220v on a 110v system would matter. I would think only the contact would be more robust to handle the extra voltage.

However, it looks like it has been "tripped" as the center elongated section is sunken down into the unit by about a 1/4". Can this be reset? Also, there is a cover on the unit that is held down by two screws and seems to be holding down the center section.....can I removed the cover and reset the unit that way?

Mandalay Parr on 12/19/16 03:29pm

Probably 120 volt.
Probably easier to replace whole switch. Probably have to remove it anyway to replace one of the contactors.
Have you opened it up to take a look?

What issue are you having?

The whole switch runs about $300 bucks....the one contactor runs about $75. Nope, don't have to remove the whole switch to remove the contactor. Yes, I've opened it up and taken voltage measurements.

The issue is that 120v is going into the contactor but nothing coming out. Hence, no 120v shore power. Generator contactor works just fine.

Thanks for replying... appreciate it.

Ron

A 50 amp transfer switch uses (2) three pole relays
Some new coils are DC with a rectifier control board, eliminates humming

The older versions all use 120v coils in the relays

The really good ones have mechanical interlock between the two contactors, do only one can pull in at any time
"Todd" Transfer switches were Built that way

Finding a single replacement part could be hard to do

Both contactors will be three pole, normally open contacts. The contacts must be rated at least 50 amps. The coil voltage will be determined by the type of transfer switch you have. Some may be 120v, and some may be 24v. It will say the voltage on the old coil. Replace it with the same voltage. The typical contactors will be what is known as "IEC" style as opposed to "NEMA" style. It would be difficult to find one that isn't rated with a high enough voltage on the contacts. The highest voltage you will see at the contacts is 120v to ground.

It might well vary depending on the model of transfer switch. If they are replaceable, they would presumably have to be swapped only for a precise exact replacement to maintain safety and safety certifications.

The coils for the relays (contactors) would be 120V coils because otherwise 30A shore power or many RV generators would not work (as they connect both hot lines to the same phase). The contacts I would think would have to be rated for 240V operation in as much as the hot lines, at least, could see that voltage across them depending on the precise timing of the opening of the other contacts. The difference between contacts rated for 240VAC and those rated for 120VAC is probably as much regulatory paperwork as anything; it's not a huge physical change.

Probably 120 volt.
Probably easier to replace whole switch. Probably have to remove it anyway to replace one of the contactors.
Have you opened it up to take a look?

What issue are you having?