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bc1641 · Mar 21, 2008, 11:52 AM

Hello,

I have a project that I'm working on and had to purchase a 3 phase motor that requires 480V. Looking at past posts, it appears that several people are familiar with 480V 3 phase motors. What do I need to do/build to power it?

Thanks!

stanfortyman · Mar 21, 2008, 12:37 PM

Move into a building that has 277/480v power. Then hire an electrician to hook it up.

Three-phase, ESPECIALLY 480v, is NO place anyone other than an experienced, licensed, insured, electrical contractor should even consider messing around!
Besides, this is commercial. I'll all but guarantee that it would be illegal for you to do this work.

It is FAR beyond the realm of reality to do what you intend. There are phase converters to go from single phase to 3-phase of the same voltage. To go from 120/240v single phase, to 480v three-phase is a serious and EXPENSIVE undertaking, if it can even be done on your site.
Get a single phase 240v motor.

bc1641 · Mar 21, 2008, 01:07 PM

Thanks for your post... I'm actually a researcher at a university and need the motor to drive an experiment. I needed a motor that could hand a 50 in-lb torque with at least 180 rpm and the only motor I could find was this 3 hp motor. I thought I might be able to use some transformers to power the motor, but from what you are saying it is a bigger task than that?

stanfortyman · Mar 21, 2008, 01:18 PM

Originally Posted by bc1641

Thanks for your post... I'm actually a researcher at a university and need the motor to drive an experiment. I needed a motor that could hand a 50 in-lb torque with at least 180 rpm and the only motor I could find was this 3 hp motor. I thought I might be able to use some transformers to power the motor, but from what you are saying it is a bigger task than that?

An absolutely FAR bigger task!

For that kind of experiment why can't you just get a 120v motor with a gear reduction drive? 180rpm is SLOW.
You will NOT find a motor to go that slow directly, unless you get some kind of stepper motor or the like.

bc1641 · Mar 21, 2008, 01:29 PM

Originally Posted by stanfortyman

An absolutely FAR bigger task!

For that kind of experiment why can't you just get a 120v motor with a gear reduction drive? 180rpm is SLOW.
You will NOT find a motor to go that slow directly, unless you get some kind of stepper motor or the like.

The problem is more about the torque than the speed. I've searched for a motor with 100 in-lb as a safety factor. That's a pretty tough load. Do they make 120v motors that can handle that? My current motor (that was laying around) was 57 max-torque load, 170 rpm and couldn't even move the device.

bc1641 · Mar 21, 2008, 02:03 PM

Originally Posted by stanfortyman

An absolutely FAR bigger task!

For that kind of experiment why can't you just get a 120v motor with a gear reduction drive? 180rpm is SLOW.
You will NOT find a motor to go that slow directly, unless you get some kind of stepper motor or the like.

Thanks for all your help!

KISS · Mar 21, 2008, 05:21 PM

50 in-lbs is like almost like no torque.

That RPM and torque range you can probably find in a synchronous gear reduction motor. With a synchonous motor the speed will be constant.

If you need variable speed then a pulse width modulated DC motor could work.

There are solid state speed controls that use single phase input to drive a three phase motor. These are rather inexpensive, but it would likely be operating a motor at about 10% of it's synchonous speed.