3 ph motor

[Joebob37]

I have a vintage 1/2 hp 3 ph Rockwell bench grinder w/ only 2 wires. I took it all apart, & theres only 2 wires coming from the stator. no sign of any burning, & no sign of any additional wires ever being there. the tag says "This motor has 3 wire leads" I can give some pics, & more details if needed. Hope someone has some answers.
Cheers
Joebob

 

[Norcal]

Photos will be very helpful.

 

[LS6 Tommy]

Maybe it's a 2 phase motor...

Sorry. No help. I bet one lead broke off somewhere along the line. 1/2 horse is small for 3 ph. Sure it's not 1 ph? Pics would be good.

Tommy

 

[canbug]

There's a good chance that it is single phase with a ground? The third wire may have been attached to the frame somewhere. Just a thought.

Tim

 

[big.jim]

does it say it is 3 phase or just 3 leads, is there a rating plate ,does it look like it could have a capacitor

 

[G_P]

Pics are definitely needed.

 

[Joebob37]

Hi guys;
Here's some pics. There are only 2 black wires coming out of the frame. The guy I bought it from thought it was single phase cuz of the 2 wires. If I remember right, he said when he plugged it in, it either hummed or turned slowly.
Cheers
Bob

 

[dowmace]

Have you ohmed between the two leads? You should have a low ohm reading. Now ohm to the case and see what you get preferably nothing. I don't see where you should have had an extra leg.

Something is sketchy with it for sure. It's almost like someone pulled the casing and put new windings inside or something.

 

[nehog]

I'd inspect where the two existing wires enter the winding area and see if there is one more (broken off) wire there. I think it is a three phase motor (no capacitor to start, no switch) with a missing/broken wire.

Edit: check the area about 6 o'clock in your first picture. There are two pieces of tubing the 'top' one appears to have no wire to the right side.

Also inspect the windings to make sure that none have overheated.

 

[alfredeneuman]

If you zoom in on the left lower picture it appears that 2 or 3 of the windings are burnt to a crisp.

It still doesn't explain the missing third lead though

 

[larry_g]

The signage 'to reverse rotation change any connection of two leads' tells me this is a 3 phase motor. Your missing a connection wire.

lg
no neat sig line

 

[DC73]

Take it into a local electric motor shop and get their opinion. It wouldn't surprise me to find that somewhere along the line, someone had it converted from 3ph to use at a house or business that didn't have 3 phase service.

DC

 

[big.jim]

says three phase on the plate looks to me to have a burnt winding and probably a burnt off lead so either needs rewinding or dumping and replacing

 

[DonPowers]

Take it into a local electric motor shop and get their opinion. It wouldn't surprise me to find that somewhere along the line, someone had it converted from 3ph to use at a house or business that didn't have 3 phase service.

DC

Agree, that was my first thought that it may have been rewound in the past. If not, the shop could rewind it if it has a bad/burnt coil. In any event, bringing it to a shop is your best bet.

 

[Joebob37]

Yes, I think there is definitly a wire missing, but no evidence of it. I ohm'd the 2 wires together, bout 12 ohms, & infinity to gnd. The windings are not burned, it's the camera.I may start undoing ties, got nothing to loose. Thanks all you guys for your info.
Cheers
Joebob

 

[tooler]

Did you try running it on single phase? How was the switch wired? A 3 phase 3600 rpm motor should have 6 identical coils (windings). I would let an expert look at it before digging in to it.
Rob

 

[Joebob37]

A friend suggested maybe it's 220V, 1 ph. Never thought of that. But there's no capacitor or starting switch.

 

[404]

Is there something broken off in the sleeve marked?

 

[Joebob37]

No, 404, some wires connect in the tubes & come out the same side, so looks like one is missing.

 

[404]

Bummer. Only thought is to take it like that to a motor rebuild place and ask. If the first guy you talk to doesn't know ask if someone else can come out to look at it.

 

[abk241]

I'd inspect where the two existing wires enter the winding area and see if there is one more (broken off) wire there. I think it is a three phase motor (no capacitor to start, no switch) with a missing/broken wire.

Edit: check the area about 6 o'clock in your first picture. There are two pieces of tubing the 'top' one appears to have no wire to the right side.

Also inspect the windings to make sure that none have overheated.

I'm also seeing that.
Are those 2 empty holes for wire pass through at the bottom of the case?
Is that a burned up white wire sitting there? Or just a piece of twine?