Replacing magnetic contactor advice sought

[Loren Woirhaye]

Here are some not very good pictures of a toasted magnetic contactor. It's an S-C35L. It's a 35 amp 3 phase contactor from Asia. It's probably about 25 years old. It looks to me like the basic contactor is stacked on another thing, a base, which I think functions to provide 110v power to a pneumatic solenoid valve. It's from a 13" wide belt sander made by JET. The machine is old enough that there's no manual available on the JET site. I haven't called JET, but in any case I have doubts as to whether they'd have this part. The contactor doesn't work very well starting the motor but will do so. The contacts are in bad condition so it chatters sometimes. The other problem is when the air is hooked up, the contactor chatters on and off and this turns the solenoid on and off which pulses the pneumatic brake cylinder and works against the motor getting started.

It need replacing in any case. I think what I need is just the top part, but I need one that is compatible with the 110v base part. So it's a spec and mounting issue. I've taken it apart and examined everything. The coils inside look good. Only the contacts are bad.

I don't want to spend a lot of money replacing this part on a machine that may have other problems, so I'm looking for the least costly short term way to get this working so I can further assess the status of the machine.

I appreciate any insight on repairing or replacing the top part of this sort of stacked unit.

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[Loren Woirhaye]

I ordered a similar one made by Toshiba on ebay. I'm certain I can figure out how to make it work.

[jack forsberg]

All you need to do is clean the contacts with 220 grit sand paper. be good for another 20 years. what you have is NEMA and not a cheap IEC starter.

[Loren Woirhaye]

The contacts are damaged beyond salvage.

[Bill Bukovec]

Hi Loren,

Are you using three phase?

Have you tried running the machine by wiring the power cord directly to the motor, then plugging the cord into the wall socket.

Feel free to PM me if you want further help.

Bill

[Loren Woirhaye]

It's a complex 3 phase machine. The main and feed motors run fine but when air is connected the pneumatic brake pulses because the solenoid valve gets confused (so to speak) about whether its supposed to stop or go and this becomes a problem with starting with the air connected. The contacts are damaged so badly no amount of surfacing will fix them. I know that trick and have used it on other machines. It may be the solenoid valve needs replacing, but the magnetic starter definitely does.

[jack forsberg]

The contacts are damaged beyond salvage.

do you have a pic of the contacts? and if they are as you say than the starter is to small. starter are HP/voltage rated and can have higher amps rating on the over load but that is not how that are sized. Could be your starter is under size? ( contract are HP rated) What HP are your running and at what voltage

[Loren Woirhaye]

Some of the contacts de-soldered and fell off. I soldered them on again and they fell off again. Trust me when I say it is smoked. If I could get the parts and replace the copper contact armatures (a $.25 part I am sure), I would. The contactor is from Asia and only available in bulk shipments abroad. The idea of getting new replacement parts is preposterous. It is remotely possible the Hitachi I have on order will be capable of parts donorship, which would save me the hassle of re-routing the 110v. coil outside the contactor case.

My query is really not about fixing this contactor, because it is broken for sure. It is about contactor formats and the use of a 110v coil passing through within the base of a 3 phase contactor.

[Rod Sheridan]

Hi, just take it to a local electrical supplier and purchase a new complete contactor.

The bottom part is the coil assembly............Rod.

[Don Sundberg]

What size motor is it controlling? Look at this (http://www.engineeringtoolbox.com/nema-starters-d_918.html) chart as 35 amps is not a normal NEMA rating although it looks like a NEMA starter. I am guessing a Size 2. Go to ebay and find yourself a decent deal on a the correct sized starter with 120V coil of american vintage.

New from your electrical supply place will probably be $300+ for a NEMA starter. I was pricing a size 0 with enclosure recently for a Wellsaw at work and ended up going with an NOS Furnas one for $80.

[Loren Woirhaye]

Thanks for the feedback.

See post #2