motor used to start a 3ph motor

[donselectric]

hi guys,
anyone ever use a single phase motor to start a 3ph motor and run ?
i have a guy that wants to do that for a metal brake. i remember motor- gen
sets in school but dont know how this would work or how to wire it .
i would think it would single phase cause he said it was just to start
the 3ph motor ....thanks

 

[mikeames]

I am confused? Is this some type of rotary phase converter?

 

[Little Bill]

I am confused? Is this some type of rotary phase converter?

It's not a phase converter, at least not what I know of it. I won't be much help but I knew a guy that used to work on industrial sewing machines at his house. The motors were 3PH about 1/2-1 HP. He used a single PH motor to run the 3 PH, but I can't remember how he wired or connected them.

 

[mikeames]

So when you say running are you using one as a generator? Or do you mean physcially turnign it shaft to shaft?

 

[donselectric]

he wants to use it for the 3rd ph...

 

[Finite10]

Still not clear, just to be sure...

Still not clear, just to be sure...

So it's not like the set-up 3/4 of the way down THIS page?

 

[eric9822]

Is he trying to run a 3 phase motor with a 1 phase service?

 

[SFBayVFD]

There are two speed motors with a start circuit and a run circuit, both fed from the same 3ph source.

Also, on some cooling towers I have seen two motors used, one for "start + low speed run" and a second motor for "high speed run" ... but both are 3ph.

With a Variable Frequency Drive you can run a 3ph motor with a single phase input, however there are sizing considerations.

 

[donselectric]

yes eric9822 thats what he's trying to do

 

[jap]

I've seen a 3 phase motor driven off of a 1 phase service that used the winding of a single phase motor to generate the 3rd phase. Not practical or efficient but it worked and was pretty interesting.
I was too green at the time to look into how he had it wired.

 

[xformer]

I've seen a 3 phase motor driven off of a 1 phase service that used the winding of a single phase motor to generate the 3rd phase. Not practical or efficient but it worked and was pretty interesting.
I was too green at the time to look into how he had it wired.

And how would that be wired?

 

[jap]

As I said,,,,,, I didnt take the time to understand it,,,, but it was functioning.
It was my wife's grandfather who was an electrician in Blackwell Oklahoma who had it wired up to run a 3ph piece of equipment in his garage.

 

[eric9822]

Jraef posted some good info in Don's other thread.

http://forums.mikeholt.com/showthread.php/136286-3ph-motor-started-with-1ph-motor