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Unisaw motor - 1 or 3 phase??

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Forum topic by bbc557ci posted 12-29-2013 01:10 AM 1023 views 0 times favorited 62 replies Add to Favorites Watch
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bbc557ci

543 posts in 760 days


12-29-2013 01:10 AM

I really need some help/advice here Gents.

I’ve posted a few pics of the switch, plug, and motor to my Unisaw (model 34-459). I bought the saw used over the summer for $500.00 and the guy that sold it to me said he ran it on 220V. I’ve been working on getting my shop together and have been using the Uni for a few small shop related projects, but run time has been pretty limited, but it seemed to run just fine. Well, tonight it quit running. I was thinking maybe a bad switch so I took the cover off the switch and all looked ok. So I put the cover back on the switch and hit the ON button. The quickly quit and the switch began to smoke so I unplugged the saw and began taking a closer look at things. Before the switch began to smoke, I tried to re-start the saw, and a couple of times it would start, but only for a half second or so, then would shut off again. Last attempt is when smoke came from the switch.

Please be aware I know next to nothing about elec. motors, switches, phase 1, 3, etc. But looking at the switch it looks awful busy for a run of the mill on/off switch. Tag on the saw says it’s a 3 phase motor but because the seller told me he had run it on 220v, I thought the motor had been swapped out for a single phase…. maybe not? Also, the tag/info on the switch looks like its giving specs for 3 phase wiring. And the tag on the motor is missing so I can’t get any info there.

Can anyone tell me what I have under the hood here for a motor?
If this a 3 phase motor, I’ll should probably go motor shopping.

Thanks in advance!!

-- Bill, central NY...no where near the "big apple"


62 replies so far

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JustJoe

1554 posts in 724 days


#1 posted 12-29-2013 01:14 AM

Maybe he meant it was 3-phase 220V, or that he ran it using an RPC/SPC or VFD off 220V.
What does the motor itself say? Not the saw, not the switch, the motor itself?

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bbc557ci

543 posts in 760 days


#2 posted 12-29-2013 01:16 AM

Joe – there’s no tag on the motor, so I have no way of knowing much of anything about it.

-- Bill, central NY...no where near the "big apple"

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JustJoe

1554 posts in 724 days


#3 posted 12-29-2013 01:19 AM

OK, I can only read the bottom part of the switch – there is glare up top. Does it have any rating for different voltages on it? And was the plug on the machine when you bought it, or did you put the plug on?

And how many wires are coming out of the motor into the switch, if you can see it?
EDIT: I should have looked at the pic of the motor. Are those two bumps on the side? If so then those are start/run capacitors and as far as I know 3-phase motors don’t have them (none of mine do) so it is indeed a 1-phase motor.

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Nowater

8 posts in 626 days


#4 posted 12-29-2013 01:21 AM

The open electrical box is a motor starter for the Unisaw, which so far looks normal. Can you post another clear picture of the nameplate data, as I can’t read it for the glare or poor focus?

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bbc557ci

543 posts in 760 days


#5 posted 12-29-2013 01:34 AM

I put the plug on.

Switch wiring is pretty tight but looks like just 3 wires coming from the motor to the switch.

Yes – two “bumps”

I’ll go back and see if I can get a better pic of the tag on the switch, it does give different hp at different voltages.

Nowater – The pic/elec box you are referring to is actually the on/off switch. That’s the only thing I took apart.

-- Bill, central NY...no where near the "big apple"

View Jerry's profile

Jerry

2206 posts in 2233 days


#6 posted 12-29-2013 01:43 AM

Your plug is only wired with 2 hots and a ground, which would be single phase. If it were 2 phase, then there would be 3 hots and a ground on the plug. However, there is a small possibility of the motor being 3 phase and the previous owner wired in a static phase converter and thus the plug would be 2 hots and a ground, however I believe since the motor has the start and run capacitors then it more likely is a 3 phase. To be sure one way or another, you can remove cover on motor that houses the wires, and check to see if you have 3 hots coming from motor to switch, or just 2 hots from motor to switch.

-- Jerry Nettrour, San Antonio, www.topqualitycabinets.net

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JustJoe

1554 posts in 724 days


#7 posted 12-29-2013 01:44 AM

Yea that’s a normal single phase 220V motor with start and run capacitors. The switch box (on/off box) is large because it is a magnetic switch

It is possible your switch fried, if that is where the magic smoke appeared.
You can try bypassing the switch and wiring the motor directly to the plug and plugging it in. If it runs, then you know it is the switch. There may be a buildup of dust inside (it looks dirty) causing a short, or it may have just decided it was time to go bye-bye and you’ll need to buy a new one.

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bbc557ci

543 posts in 760 days


#8 posted 12-29-2013 01:50 AM

Ok… better pic of the bumps/capacitors, and the label on the inside of the switch.

Can you read the label ok?

edit;;; Crap, still can’t read the damn label. I’ll try and down load it directly from my camera (computer illiterate too!! LOL

-- Bill, central NY...no where near the "big apple"

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Grandpa

3182 posts in 1361 days


#9 posted 12-29-2013 01:52 AM

I am leaning toward a new switch control. It ran fine for awhile then it smoked. I think the voltage and phase are fine. It might be cheaper in the long haul to get a person that wires motors to come to your shop and look at making the repair.

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bbc557ci

543 posts in 760 days


#10 posted 12-29-2013 01:54 AM

Any better?

Nope…still sux :o(

-- Bill, central NY...no where near the "big apple"

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JustJoe

1554 posts in 724 days


#11 posted 12-29-2013 01:58 AM

Yes, it might be the original 3-phase on/off magnetic switch. But pros (of which I am not) can and have used them to control single phase motors if they fit. At that level it’s magic to me but if you google around something like “3-phase on/off switch to power single phase” you might find someone who has done it.

But I think you’re right in thinking the motor and phase are fine, the switch is not. You can buy replacement switches online. If you live in a city with a decent electrical supply store they might have one for sale too. I would still wire the motor directly to a plug and plug it into the wall once just to be 100% certain that there is no problem with the motor.

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bbc557ci

543 posts in 760 days


#12 posted 12-29-2013 02:11 AM

Joe – At the moment I have it on a 50 amp breaker and 6/3 wire, which is what I had left over from the sub panel install in the garage/shop. I need to pick up a 20 or 30 amp breaker, along with some 10 ga. wire for the Uni run. I’ll try and get to that tomorrow. I’m afraid if I plug it into the 50 amp/6 ga. I might fry something!! Also, the motor/switch acted up on me once a couple of days ago and I thought it might be the switch, so I already have a switch on order. It’s a paddle type, much easier to get to the “off” position. As it is now (or was) I have to bend down and look for the damn switch to shut’r off….was driving me nutz.

Thanks everyone for the input, I appreciate it!!

-- Bill, central NY...no where near the "big apple"

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Jim Jakosh

11722 posts in 1791 days


#13 posted 12-29-2013 02:15 AM

Before plugging in anything, I would check to see if there are 4 wires going to the motor or 3. The plug is wired as a single phase 220 one, but the motor might be wired 3 phase…Jim

-- Jim Jakosh.....Practical Wood Products...........Learn something new every day!! Variety is the Spice of Life!!

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JustJoe

1554 posts in 724 days


#14 posted 12-29-2013 02:17 AM

Well let us know when you get the new switch installed and everything is working OK.
I’m pretty much housebound myself so I like to live vicariously through other people’s adventures and it’s always a good feeling when I hear a problem is fixed.

I just don’t like it when they fix the issue and never come back to even say thanks. I talked a guy through doing his own appendix removal last month using only the items found under his seat cushions, and he still hasn’t let me know how it turned out or thanked me for saving him all that money.

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bbc557ci

543 posts in 760 days


#15 posted 12-29-2013 02:19 AM

Jim -

I plan to pull the motor tomorrow if I need to, to get to the plate. I’ll check to see how many wires there are. Too late tonight…almost 9:20 and I’m starving lol

-- Bill, central NY...no where near the "big apple"

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