To avoid these ads, REGISTER NOW!

Home built rotary phase converter

D

dieselshadow

Active member
Joined
Jan 27, 2014
Messages
41
Location
Middle TN
I've got a 5hp 3 phase 200v motor that I recently acquired. The windings look good and read 1 ohm between each leg, nothing to the case. I replaced the bearing and the rotor spins freely. I plan on using it for making 3 phase power in my shop.

I hooked two legs to 120v each out of a welding outlet. The third leg was taped up. When I turned it on I growled fairly loudly, started spinning, albeit slowly. It refused to spin up to speed. It achieved maybe 500 rpm. The wiring to the motor started getting warm so I turned it off. What am I missing here?

I've been successful in starting and running 3 phase motors on single phase. You just need to start them spinning and it takes right off and runs good.

Thoughts?
 
To avoid these ads, REGISTER NOW!
O

oldgoaly

Well-known member
Joined
Apr 3, 2006
Messages
395
Location
Shiloh, Il
needs 220 vac across the 2 of the legs 3rd leg is separated by run caps.There are different ways to make one. Mine is a self starting, unbalanced type, Jim Hanrahan's design You see the different versions here. http://metalwebnews.org/ (it was down when I tried it)

idlermotor3ph01.jpg

I run a bridgeport and a 2hp lathe, had a pullmax running off of it but traded that for a T3 pullmx running it off a vfd.
 
Last edited:
A

A_Pmech

Well-known member
Joined
May 8, 2007
Messages
8,002
Location
IL
Three-phase motors will run on single-phase but won't start on it.

To get your motor to run you need to spin it up to a fairly high percentage of rated speed. Then, field slip will be within the range where the motor can accelerate.
 
To avoid these ads, REGISTER NOW!
OP
D

dieselshadow

Active member
Joined
Jan 27, 2014
Messages
41
Location
Middle TN
That's strange. I have other little 3 phase motors that once spun even just a little bit in one direction, they take right off and spin up to full speed.

Yes. It is a 200v motor. It was in a plant as a fuel pump running on 208. It's an old motor.
 
OP
D

dieselshadow

Active member
Joined
Jan 27, 2014
Messages
41
Location
Middle TN
A_Pmech said:
Three-phase motors will run on single-phase but won't start on it.



To get your motor to run you need to spin it up to a fairly high percentage of rated speed. Then, field slip will be within the range where the motor can accelerate.
Click to expand...


Didn't think of the slip. It's probably running at mathematically 1/2 (or some other fraction) hence why it won't accelerate.

I'll try spinning it faster prior to energizing it.
 
N

Norcal

Well-known member
Joined
Mar 16, 2008
Messages
13,750
larry_g said:
http://www.metalwebnews.com/howto/ph-conv/ph-conv.html

I built one following the above instructions and have been successfully using it for 10+ years. Can you confirm the 200v rating for the motor, that is not a standard I know?

lg
no neat sig line
Click to expand...

200V is the rated voltage for motors running on 208V, it is a NEC violation to use it w/ a 240V supply, 220 is not a standard voltage anymore.

I have a couple of former school machines that are 200V 3Ø used VFD's on them, but that does not help the OP.
 
You must log in or register to reply here.
To avoid these ads, REGISTER NOW!
Top Bottom