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Tips/Techniques Finding out 3ph motor voltage without a nameplate?

Tips/Techniques

mbond

Well-Known Member
Premium Member
For those who may be interested, the most important factors skipped in this math are the power factor and the difference between impedance and resistance. There are others too, but they are all likely to be within 'spitting distance' as t were.

If it was my motor, I would just hook it up and try it. Then post a picture / video of how it runs
 
Nice looking shaper, once it's running, I think that you will enjoy it. They kinda belong with a blacksmith shop ... Speedy, they are not, versatile, they are.
I'm slowly picking away at the drive on my little shaper. I'm eliminating the Car transmission and hokey clutch setup with hopefully, a slightly less hokey, belt only system.
 

Dan Dubeau

Ultra Member
Yeah, at 13" it's a good size. A small atlas would maybe take up less room, but you'd be giving up so much more capabilities and rigidity. I don't know how much I'll use it, but If it's working, I'll find uses for it. I do have one job I want it for, and that's milling straight face grooves on putters.

I found a nice suitable 230v 3ph 2hp motor for it this morning, and I'm waiting to hear back from the seller. Path of least resistance wins every time....

Btw you were the one a couple weeks ago that put this back on my map in that thread about gear cutters. I was perfectly content to ignore it for another 10-13 years :D.
 

slow-poke

Ultra Member
One option is to bring it to the motor shop (they will likely confirm the 575V) and then you can get a quote to rewire for 240V. This might be the less expensive than a rotary converter?
 

Dan Dubeau

Ultra Member
I'm still waiting to hear back about a semi local Baldor motor for $150. 2hp 3ph 230v 1800rpm, with a 7/8" shaft (original is 7/8, not 3/4 like I guessed initially) Should be a pretty easy direct replacement. I doubt I could get someone to rewind the original for less than that, but It's a valid option. I'd still have to buy another suitable VFD, but could use my mill one for now. I need to buy one shortly for my belt grinder, so might as well buy 2...

Slightly a bit more money than what I'd need to spend to finish the Phase converter. But the quicker easier option. I already have the 5hp idler, transformer, cabinet, a few maybe suitable caps, and a 3ph contactor, but need a few more odds and ends, like switches, caps etc, and the time to finish it. I could probably "finish it" with a solid weekends worth of work, and another $100-150 at retail prices. Cheaper if I scrounge like I have been so far. Maybe over the Christmas break.....

The ease of operation of a VFD can't be understated though. In the long run I think it's the better move for all my equipment. Even if I'm slightly out of pocket a bit more initially.

If the deal for this motor falls through, I'll probably just carry on the same path I was on and finish my phase converter to power it and future additions. I'm in no great hurry to get this moving. Pretty much only dug into it yesterday to see if I needed to buy 2 VFD's or not, and got surprised by the lack of nameplate.
 

Susquatch

Ultra Member
Administrator
Moderator
Premium Member
If the deal for this motor falls through, I'll probably just carry on the same path I was on and finish my phase converter to power it and future additions.

If it were my call alone, I'd just have more replacement motors and VFDs in the shop. I'm already at 3 and I smell a 4th coming soon.

In my opinion, getting motors is all about patience. VFDs are money well spent for the control and the smoothness of the motor.

I know others will argue, but a VFD is also a great replacement for contactors and other protection circuitry. It's a control box all-in-one.
 

Dan Dubeau

Ultra Member
This was a much more frustrating transaction than it really needed to be.....but I have a new motor.....It came from a paintshop fan in a school. Apparently....
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Pulled the sheave off using my new to me puller I got from the drywall lady.....:D
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646wkmf.jpg

Checked to make sure it was wired low, and The existing leads were "just" long enough to reach the mills VFD from the mill table
90RP757.jpg
And it runs.
https://imgur.com/pmmxMtV

Interesting that it sounds loud and gravelly in the video. I get none of that in person, just the vfd high frequencies.

I'm going to order a Vevor VFD to run it.....They got me now.....
 

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Dan Dubeau

Ultra Member
It's buried in the casting, and somewhat tough to see all around. I've pulled off every cover and looked it all over as best I can with an inspection mirror where I can get one, but short of pulling the motor out to see if anything is written on it somewhere

The answer was there, in the first post all along......
kqEDdeP.jpg

It's funny, Because I kinda suspected that there might be something, but I could not see that with a mirror and flashlight. I think the bright light just washed it out. Anyway....there it is.

New motor fits. Flange pattern is off (new is smaller), but there's about 3/8" height difference (have not accurately measured it yet) that will allow me to make an adapter plate, and get back to the same pitch. Much easier than trying to tap the casting. Plus I'd need new belts for that.
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Should have it chugging by next weekend. My Christmas present to myself. About 2 hours of work and a road trip, only took 13 years lol.
 

Dan Dubeau

Ultra Member
What I'm NOT looking forward too now, is digging the engine hoist back out of the barn to lift the shaper out of that cradle and get it on the floor. I just put it away last weekend and I buried it pretty good behind a bunch of shit thinking I wouldn't need it for a while.....I don't think there another safe way I can do it without lifting from above.

I think that's probably the best solution once I get it going. Trying to come up with some sort of foot thing can be done later, if I use that cradle at all. I might just take those casters off, and put some solid feet on high enough that I can slip the pallet jack underneath. Options to think about.........
 

Dan Dubeau

Ultra Member
Based on the many used machines my Father imported from Scandinavia many years ago, I would think the motor may be 380 volt.
Perhaps you're right that it was probably originally 380, but rewound at some point to 550. That would explain the missing tag, and the fact those are the only holes in the mounting plate. I betting that's the life story of this motor. It was also probably a school machine, and judging by the paint, it was a clown school.
 
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Dan Dubeau

Ultra Member
So I fell down a youtube rabbit hole last night watching a pile motor rewinding videos......both the theory behind it, and the dirt floor sandals and rags process of it. Doesn't look that complicated. Bit of math to figure out what wire, and how many turns, winding pattern etc, but overall the physical process is honestly pretty simple albeit a bit fiddly.......There's a lot more to it than that obviously, but the information is out there.....


Anybody ever rewound a motor?
 

Ironman

Ultra Member
Yes. I was unable to successfully cram in all the wires into the slots from a pre-wound skein, so had to rewind it one wire at a time and that worked for me.
It was a one hp motor and back then the only motors you could get for your shop was from a wringer washing machine. A 1 horse motor was like a gold bar.
 

Susquatch

Ultra Member
Administrator
Moderator
Premium Member
back then the only motors you could get for your shop was from a wringer washing machine. A 1 horse motor was like a gold bar.

So true!

And the guys on here complain about not being able to find a motor.......

You have more courage than I do. I wound a few motors in my time, but just little tiny ones. Back then everyone had big hands..... LOL!
 

Susquatch

Ultra Member
Administrator
Moderator
Premium Member
Anybody ever rewound a motor?

You are on your own with this one Dan. I don't think I'd have the courage to do that. Afterward, my motor would probably have the shakes as bad as I do from all the shaky wiring. Even the shops that I know of around here use specialized winding equipment to keep the wires tight and in place.

Consider stopping in at a rewinding shop near you for a tour.
 
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