Phase Converter Motor

[Bernd]

The Bridgeport I'm getting is a 3 phase machine so I'll need a converter. I've had this motor for over 15 years now. I figured if I ever get a 3 phase machine I would have a motor to make a converter. It's a 220/440 Volt 3 phase 7.5HP 1160 RPM motor. It's all cast iron and very heavy. How do I know it's very heavy? I dropped a corner of it on my foot when I brought it home. Ouch! Of course it was accompanied by some choice words not fit for public reading. ;D

Here's a pic with a 5 gallon gas can and 20lb propane gas tank for size comparison.

I figured since I had the slide down to the basement all set I might as well get the motor down the stairs too. Almost dropped it on my foot a second time. : :big:

Hey Rick, do you think it'll work for what I want? Rotates pretty freely.

Bernd

 

[kvom]

You can run it on single phase power if you start it manually. I'd do that and run it for a few hours to see how it works, before investing in the additional components.

 

[wareagle]

First off, make sure the leads are connected for low voltage (240V). The name plate should have this information on it. As long as the windings are in good shape and haven't been cooked or shorted, then you have a workable situation. The power converter is a doable project!

 

[Bernd]

You can run it on single phase power if you start it manually. I'd do that and run it for a few hours to see how it works, before investing in the additional components.

Precisely what I was going to do.

First off, make sure the leads are connected for low voltage (240V). The name plate should have this information on it. As long as the windings are in good shape and haven't been cooked or shorted, then you have a workable situation. The power converter is a doable project!

W/E,

Read your post on 3 phase motor options. Kind of on the fence on which way to go. But I'd think I'd like to see what can be made out of this. The leads have been twisted together for the 220 volts. I need to check and make sure that none of the windings are shorted to the frame of the motor first. I'm not sure if any critters (mouse) has gone in there and done any damage. It doesn't look it, but I don't want to be surprised by a sudden "poof" of smoke when I connect it up.

Name plate has all the info I need. Shows how to wire it up delta and star and the wires have little metal tags on stating what number it is.

So, given a bit of time between getting the drill press upright, getting the Bridgeport home, closing the up the summer cottage, working on the house, I might find some time to work on the converter. :

Regards,
Bernd

 

[wareagle]

Read your post on 3 phase motor options. Kind of on the fence on which way to go. But I'd think I'd like to see what can be made out of this. The leads have been twisted together for the 220 volts. I need to check and make sure that none of the windings are shorted to the frame of the motor first. I'm not sure if any critters (mouse) has gone in there and done any damage. It doesn't look it, but I don't want to be surprised by a sudden "poof" of smoke when I connect it up.

I really doubt you'll get a puff of smoke even if you have damage. Likely it will just trip your breaker and may make a bit of noise. If the rotor turns easily (which I believe you have said it does) and the windings aren't shorted, then the motor should run without a problem.

Beware of the inrush current on start up... This motor may take as much as 50A to start. My advice would be to pull the rotor by hand and as soon as the shaft is clear, have an assistant throw the power to it. Keep them there ready to shut it off! Check to see which way it rotates by turning the shaft by hand slowly and them bumping it with power. If you are going right, the motor will try to start. If not, the shaft will stop and likely trip the breaker in the process.

Exercise extreme care when performing this operation! And I strongly encourage you to have someone else with you who knows how to turn the power off and how to summon help should something happen. With electricity, you usually don't get a second chance!

 

[Bernd]

Wareagle,

Been doing a bit of contemplating. I think I'm going to go for a VFD, but still work on the rotary. It all depends on how fast I get the Bridgeport back together in the basement and how much in a hurry I am to start running it. If the rotary isn't anywere near done I'll go for a VFD. I'll finish up the rotary and keep it as a back up should the VFD fail. A bit more money spent? Ya, but I can make it up be making stuff for the Hot Rod guys. :big:

Thanks for the warning. I used to work as an electrical tech. I got to start up machines from scratch. Used voltages up to 500 Volts. So careful is the name of the game.

Bernd