Source for mag switch contactor?

I'm trying to fix a 220v single phase machine. I believe the contactor/magnetic coil is bad.

One switch operates two motors.

Main motor is 5hp, second feed motor is 1/2 HP.

I'd like to just fix it if the contactor can be located, otherwise I'll need to source a mag switch that will operate the two motors simultaneously.

Anyone have an idea of where to find the required parts? The close-up photo is the contactor.

How did you come to the conclusion that the contactor is bad?

SAF Ω

SAF,

The electromagnet is not strong enough to lift the bottom half of the disconnect. It tries, But doesn't seem to generate the magnetic force necessary to close the circuit. Just sits there clicking and twitching.

The bottom half moves freely, no undue impediment to it moving up to close the circuit. If I shim the bottom half of the assembly up with a peice of wood about 1/16" the magnet is strong enough, though just barely, and I wouldn't trust that in use.

Check the voltage supplying your control transformer at terminals H6 & H3 should be at least 230V less than that you will not have enough output voltage on the secondary side.

Check the secondary output voltage on terminals X1 & X2 you should have at least 24VAC, less than that and there's not enough energy to pull in the contactor armature. Also check the voltage directly at the contactor coil while holding the start button.

The contactor and enclosure is mounted upside down. This will also require more energy for the armature to overcome gravity.

Did it ever work properly mounted upside down?

SAF Ω

Sounds like you have the wrong voltage to the coil. Was the machine operating before you got it? Did you change any wiring? Do you have a voltmeter to check the coil voltage? What is the voltage marking on the coil? Operating two motors from one switch is no problem.

Tom

TDegenhart said:

... Operating two motors from one switch is no problem.

Click to expand...

It is in this case. That contactor is rated for 5HP 230V, he already has that maxed out. Adding another 1/2HP 230V single phase motor is a significant additional load on that unit, the contacts will not take it for long. Correct fusing will be trickier too.

But otherwise, I agree it's more likely the voltage is wrong. Start there before jettisoning it if you are planning on just getting another separate contactor for the 1/2HP motor. If you still want to do them together with one contactor you will need to replace it with a larger contactor anyway, so no point in trying to fix it.

To do that you will need one rated for 7-1/2HP (the next size up). But also, the only viable way to run them both from one contactor is if the 1/2HP motor has integral thermal OL protection built-in, information that will be on the motor nameplate. If the nameplate doesn't SPECIFICALLY say that it is protected, you must assume it is not and use an external OL relay. The wording is usually something like "Thermally Protected", but might just be abbreviated as "TP", or something with similar meaning. Otherwise you will need to add a second OL relay to that contactor in parallel to the one for the 5HP motor and wire the aux contacts in series so that if either motor overloads, it drops out the contactor. Rather than go through all that, it just might be easier to get another small starter for the 1/2HP.

If you do need a new coil, that contactor is not likely available any longer. Rockwell, at that time that was made, did not yet own Allen-Bradley so they used electrical controls for their machinery from other sources. When they bought A-B they dumped all of their other arrangements for controls. But Rockwell is no longer in the machinery business anyway*, so there isn't anyone there to find out who actually made that contactor in order to be able to order a coil.

There is a "new" company using the name Rockwell for tooling, they are in no way related. The "new" Rockwell (RWDirect Inc., division of Positec) is a Chinese manufacturer who is surreptitiously using the Rockwell name to capitalize on the brand recognition. The "old" Rockwell International division that made tools had been merged with Delta and when Rockwell Intl. got out of the tool business, that division changed their name back to Delta International Machinery. Delta, I've heard, does not maintain records on the older Rockwell branded stuff however. I don't know that for sure, that's just what I was told at a local Delta shop when I tried to get some parts for an old table saw.

PS: I punched that contactor part # into Delta's site and got this:
Delta – Service Net >> Use 438-1-16-199
The one they say to replace it with is also not available any more.

The wiring diagram says its a Furnas control but I do not recognize the switch.

Tom

TDegenhart said:

The wiring diagram says its a Furnas control but I do not recognize the switch.

Tom

Click to expand...

Oh yeah, I see. I missed that. But it's a Definite Purpose contactor and Furnas sold out to Siemens, then Siemens got out of the DP contactor business a decade ago. So still no parts available for that one.

I could probably make a new coil, but it also probably would not be worth the trouble. It wold be easier to scrounge a little larger contactor. I am in the wrong voltage camp, anyway. If the coil has shorted turns, it would have done a full blown burnout. Remember that leaving voltage on it without it pulling all the way in will also smoke it. These coils draw a large surge when open, then drop down to a small current after the magnetic path is complete. The maker used that effect to generate a strong magnetic field to pull it in, then it only requires a small holding current.

Bill