Unisaw Motor Help

[Michael Pauly]

I finally got a chance to haul the unisaw I picked up used in the spring down to the shop, set it up and wire up a new 220v outlet. Got everything hooked up and the motor won't turn. Now when I bought the saw we tested everything out and things seemed to work properly so something obviously went wrong in the time I moved it and set it back up.

To move it down to my shop, I had to take the CI table off and remove the motor to lighten the load. There were no incidents in the move and I got it all put back together correctly (or so I thought), but honestly, there could be something wrong anywhere in the chain. Here's what I know right now:

- Definitely a 1-phase 220v 3hp motor
- I have 120-129 v on each leg of the new outlet (seems to be wired correctly)
- When I reconnected the motor, I hooked up the two hot leads to the corresponding hot leads coming from the switch and connected the ground from the switch to the grounding screw on the motor (there's no grounding wire on the motor)
- When I press the 'on' button on the magnetic switch, I get 120-129v on each side of the hot leads at the motor tested between the lead and the grounding screw.
- The magnetic switch doesn't stay 'on', acts like a momentary switch

Here are my questions:
1. From my research, I've seen mention of bad capacitors, but how would I check that and why would it go bad from the test run till now (no use in between)?
2. Should the magnetic switch be staying 'on' or does it require a closed circuit on the motor end? If the latter, would point to an issue at the motor?
3. What should I be looking at next?

Thanks in advance for any help.
Michael

[M Toupin]

When I press the 'on' button on the magnetic switch, I get 120-129v on each side of the hot leads at the motor tested between the lead and the grounding screw.

If you hooked everything up exactly like it was when you tool it apart then don't be so quick to blame the motor. It's highly unlikely the motor went bad for no reason.

The question is do you have 220v across L1 & L2?

If the new breaker is improperly installed and pulls from the same leg then you will get 110v & 110v but you won't have 220v. Seen it more than once, check your wiring again.

Mike

[Chip Lindley]

If you are getting current to the motor leads after the magnetic starter ON button is pressed, the starter is doing its job. The momentary ON and OFF buttons only energize the coil to close the contacts to start the motor, and break contact to stop it. These magnetic starters offer the safety feature that if current is interrupted while using a machine, the machine will not start up again when the power is restored until the ON button is pushed.

That being said, if you have 220V current through the starter to the motor leads, either the motor is not wired correctly or you have other more serious problems with capacitor or windings. Double check your motor connections against the diagram on the motor nameplate, or inside the cover of the motor connection housing. There also may be a "reset" button on the motor that has tripped. Lastly, a single phase motor has a starter winding inside, with contacts which are closed to start the motor under load, then open by centrifugal force as the motor gains full speed. These contacts may be stuck open or corroded.

You have picked my meager brain to the max and I must go lay down now! Good Luck!!

[Rick Thom]

If you hooked everything up exactly like it was when you tool it apart then don't be so quick to blame the motor. It's highly unlikely the motor went bad for no reason.

The question is do you have 220v across L1 & L2?

If the new breaker is improperly installed and pulls from the same leg then you will get 110v & 110v but you won't have 220v. Seen it more than once, check your wiring again.

Mike
If you have another 220V piece of equipment that you know is good, try it on your new circuit to prove that circuit is good. Go for the obvious and easy stuff first.

[Michael Pauly]

If you hooked everything up exactly like it was when you tool it apart then don't be so quick to blame the motor. It's highly unlikely the motor went bad for no reason.

The question is do you have 220v across L1 & L2?

If the new breaker is improperly installed and pulls from the same leg then you will get 110v & 110v but you won't have 220v. Seen it more than once, check your wiring again.

Mike

Bingo!! Didn't realize it, but had the breaker installed wrong and like an idiot was not checking across phases (only cchecked phase to ground). As suggested, moving the breaker down 1 slot ured the problem and she's purring along.

Now I need to adjust the rear collar on the height adjustment shaft....it's jumping a bit on startup.


Thanks for the help.

Michael