Need help getting this electric motor running

[iScream]

Hey guys,

Almost 10 years ago I bought a Jet hybrid table saw called a Super Saw. When I got it in my garage the first thing I did was follow the really simple diagram to wire it for 220V. But as soon as I plugged it in the smoke came out of it. Never even spun.

Jet sent me a complete motor to replace it which I wired for 220 and it ran just fine. But they didn't want this one back so it's been sitting in a corner all this time. I sold that table saw to my step dad a few years ago but now I'm wanting something better than the little Dewalt contractors saw I have right now.

So, I'm hoping I might be able to pick up an older three phase saw pretty cheap and replace the motor with this single phase. If I can manage to repair whatever went up in smoke for a reasonable price.

I have some education in electronics so I know my way around DC stuff pretty well and I know the basics of AC, like what chokes and capacitors do and what impedance is, etc. But I don't really know where to even start troubleshooting this motor.

Can someone please kinda get me going here? I'm not afraid of reading or research and I'll be Google searching some tonight but GJ seems like a great place to ask for some help.

I dug it out a minute ago and snapped a quick picture of the label. I can take off covers and snap more pictures or whatever if it helps.

Thanks a whole bunch for any help.

-Chris

 

[engnerdan]

Too little info, a single phase AC induction motor only has a couple pats.
1. Field winding (hundreds of feet of enamel coated magnet wire, tightly wound, packed, and sometime varnished or epoxied in place
2. Some capacitors, if it has 1 its a starting capacitor, if it has 2 then it also has a run capacitor
3. A mechanical starting switch, actuated by motor speed to shut off the starting circuit after a certain RPM has been reached.
4. The junction box/ jumpers for voltage selection.

If all of the field windings are in tact and not shorted then I would say there is a chance of fixing it. But if a field winding is toasted, there is about a 0% chance it is worth fixing.

If you come across a 3 phase table saw 3hp or less you can buy a single phase to 3 phase motor drive for about $100 per HP or less if you want to dabble in ebay china imports.

-Dan

PS - The last motor I took to a motor shop was a 2HP 3 phase motor with over heated windings. The motor was $400 new and I was quoted $450 to rewind it.

 

[Indexmill]

How much of the magic smoke came out? A little for a fraction of a second while you immediately unplugged it? Or lots because you did not unplug it?

Seriously, you may be lucky. Ohm out the windings; if not open or shorted to the case then double check your connections for the line voltage and give it another try. I have seen way stranger things happen...

 

[iScream]

Too little info, a single phase AC induction motor only has a couple pats.
1. Field winding (hundreds of feet of enamel coated magnet wire, tightly wound, packed, and sometime varnished or epoxied in place
2. Some capacitors, if it has 1 its a starting capacitor, if it has 2 then it also has a run capacitor
3. A mechanical starting switch, actuated by motor speed to shut off the starting circuit after a certain RPM has been reached.
4. The junction box/ jumpers for voltage selection.

If all of the field windings are in tact and not shorted then I would say there is a chance of fixing it. But if a field winding is toasted, there is about a 0% chance it is worth fixing.

If you come across a 3 phase table saw 3hp or less you can buy a single phase to 3 phase motor drive for about $100 per HP or less if you want to dabble in ebay china imports.

-Dan

PS - The last motor I took to a motor shop was a 2HP 3 phase motor with over heated windings. The motor was $400 new and I was quoted $450 to rewind it.

Thanks. It was years ago and I just don't remember exactly what happened. I believe it was a very quick puff of smoke as soon as I plugged the cord in. I was and am still pretty sure I wired it right, per the diagram. It was pretty simple. I'm thinking something internally was wired wrong from the factory as it was a brand new saw and motor.

I don't think I ever got to the point of turning on the power switch.

It also sounds like I may have overestimated the value of this motor and what I would be getting for my time if it can be fixed.

But I'm going to take the covers off of it one evening and see if it's obvious what went ****. The thing has zero run time on it.

-Chris

 

[raddksn]

Might be just a capasitor smoked.

 

[iScream]

How much of the magic smoke came out? A little for a fraction of a second while you immediately unplugged it? Or lots because you did not unplug it?

Seriously, you may be lucky. Ohm out the windings; if not open or shorted to the case then double check your connections for the line voltage and give it another try. I have seen way stranger things happen...

If I remember right, it was a little smoke immediately when I plugged it in the first time. I don't remember feeling the need to run for the plug like it was shorted or anything.

I'm 99 percent sure I never got the chance to hit the power switch.

-Chris

 

[scw1991]

you can accidently plug a 230v wired motor into a 115v circuit. However, if you try and plug a 115v wired motor into a 230v circuit, you'll fry it.

 

[iScream]

you can accidently plug a 230v wired motor into a 115v circuit. However, if you try and plug a 115v wired motor into a 230v circuit, you'll fry it.

I'm 100 percent sure that didn't happen.

 

[iScream]

I took the motor apart this afternoon. I'm interested as much in learning about it as fixing it at this point.

It has both a start capacitor and a run capacitor. Both look perfect. I disconnected both and tested them by setting my ohm meter to 2K then touching both wires. Both capacitors briefly show a low resistance reading but it quickly climbs to infinity. It makes sense to me that switching the leads should cause the same thing to happen again so I tried it and did get the same thing.

I don't see anything obviously burned or melted or anything but much of it isn't visible.

So what else do I check at this point? That the windings aren't shorted to the case and that the windings aren't open? Does the picture below show enough to know where I should measure?

It was cool seeing how the centrifugal switch works to go from the start capacitor to the run capacitor. I had no idea that was in there. I'd like to understand how the internal wiring works so that the start capacitor is rated 125V AC but the motor can be wired for 220.

Thanks,
Chris