[How-To] Low voltage 480v motor?????

[graham-xrf]

Can a motor, wired to the 3 phase input in what a typical diagram would consider "Low Voltage" actually be expecting 480 volts? Do those motors exist? If the simple answer is "no" - then I can worry about the causes when I need to.

Leaving out information to limit your question in the hope of a binary Yes/No answer greatly increases the chances of the question being moot. You will only really feel OK when switching on if you have got enough from the folk here to understand the motor, and it's connections to the extent you feel confident.

When a motor has six windings, the (many) ways they can commonly be used is always potentially complicated.
I definitely go +1 on @strantor 's "With 95% probability: no" except I would change the percentage to 99%.

We have pretty much got there on everything about what it is, and how to connect it. It should not take very much more to check it out, and find out why it acts as it does. Probably, you don't even have to take it apart any further than taking the connections off. If you find something wrong, then open. If it's something simple, then fix it. You will have a good powerful working thing with a long life, and you will understand everything about it. If you find its a wreck inside, then by all means replace it.

Your nameplate image is not clear enough to see the motor power (HP?), but from multiplying the voltage by the current for both cases, we get 1276Watts, or 1.7 horsepower. It may be rated 1.5HP, allowing for efficiency, and phase lag.

I sense you wanted a quick fix, and you are reluctant to open it regardless.
OK then, if you are considering a replacement, get a 2HP motor with the same shaft for your pulley.
Note: A brand new one might still come with the "how do I connect it" questions!

Regardless whether new or nicely fixed up, if you also get a VFD, it will have you smiling, and you won't even need the rotary converter

 

[MyLilMule]

Regardless whether new or nicely fixed up, if you also get a VFD, it will have you smiling, and you won't even need the rotary converter

I won't normally say never, but I can guarantee I will NEVER use a VFD on one of my vintage machines. Never. It's a matter of principle. LOL!

 

[graham-xrf]

I won't normally say never, but I can guarantee I will NEVER use a VFD on one of my vintage machines. Never. It's a matter of principle. LOL!

Heh Heh!
I do agree that a nice working vintage precision machine should keep it's patina, proudly show off it's dings, and have everything else well oiled, and maintained. Having a VFD in the scheme does somewhat spoil the mood.

I have a different philosophy. I think vintage old machinery can proudly demonstrate that it can handle new fangled electrics offered at it! The VFD doe not have to be mounted where one can see it.

I confess I have once removed the dangerous, failure prone, and carcinogenic innards of an electrolytic capacitor in a vintage wartime aircraft R1155 radio receiver. I hid a modern, much better capacitor inside the original metal body, and used the original terminals. Was that a cheat?

 

[MyLilMule]

I've resisted the urge to put a DRO on anything older than 30 or 40 years old. The Bridgeport is the only one I have a DRO on at the moment.

This new machine is in a a bit better shape (motor excluded) than the other lathe I have. There's so much wear in the ways, it seemed like a waste. This one, if I keep it, might end up getting one. Yet to be determined. Considering the ways are in good shape AND it has a spindle bore that can (with ad adapter) take a 5C collet, making slightly more precise parts might benefit a little more. I haven't determined just how bad any of the lead screws/nuts are, so that may affect my decision or at least my timeline if any of them need remade.

Both this SBL and my current one had such bad paint jobs, there's no way they weren't getting repainted.

 

[strantor]

A lot to consider once I finally get it inside. I doubt I will have this motor fixed. More likely replace it with a newer 3 phase.

Something's definitely amiss with that motor. I wouldn't try running it anymore until you figure out what it is, and if you can fix it. It could be as simple as a loose wire nut somewhere. Seems like the speed is dropping by half at least, so amps are probably shooting up way higher than the nameplate value, and you might end up burning up what is currently a salvageable motor. Is there an overload on it anywhere?

 

[MyLilMule]

There's a switch on the back of it, with what I think are some kind of heaters, but I'm pretty sure it's junk. Won't stay in the ON position (with or without the cover). I don't trust any of the wiring in it anyway. It'll get removed and replaced. Never have on any machine I have ever bought. I always look at the wiring and make sure it's what I expect.

 

[strantor]

There's a switch on the back of it, with what I think are some kind of heaters,

yeah that's a motor starter/overload contactor. It's job is to keep the motor from burning itself up when it stalls out or in situations like you're experiencing.

but I'm pretty sure it's junk.

maybe. It could actually be the cause of your motor issues. Or it could be doing its job protecting your motor depending on what you mean by

Won't stay in the ON position (with or without the cover).

do you mean while it's got no power to it? Or does start popping out of the "on" position only while you're running the motor?

I don't trust any of the wiring in it anyway. It'll get removed and replaced. Never have on any machine I have ever bought. I always look at the wiring and make sure it's what I expect.

Good call!