step up transformer or change motor

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pedrobilt

New member
I am running my home shop through a 10 hp 26.2 A @ 230 v rotary ph converter to run my small lathe ,mill and drill press,I want to buy a larger lathe,but it has a strictly 460 v 8hp motor,should i change motor,get aa step up transformer,and can i run transformer after ph converter or do i need to go through transformer first?
 
You should price both a transformer and a motor. The down side of a transformer is you will see 1.5 to 3% eff loss in heat, and you are allready at capacity on your rotory converter. If you are only using the new lathe at one time, the transformer will work. I think a 7 kva.

The transformer will go between the rotory output and the starter box for the 480 v motor.

If you change the motor you will need to change the motor overload protection in the starter box, because your amps will be doubling at 230 volt not 480 volt.

Paul Polakoff
 

cadpoint

Senior Member
Location
Durham, NC
Welcome to the Forum!

If it's available on the Pole close to you then get the POCO involved!

I believe the Local AHJ would also want to know if the POCO say yes. :)
 

__dan

Senior Member
Look at the motor again. Open up the tap box on the motor where the power whip attaches. If there are nine leads in the tap box going in to the motor, it could easily be a dual voltage motor and accept straight 230 volt 3 phase by changing the tap leads arrangement. If you see nine leads in the motor tap box, I would contact the motor manufacturer with the nameplate information and they can provide a wiring diagram. Dual voltage motors are very common. Only three leads in the tap box would be a single voltage motor (rare).

Changing to 230 volt into the motor will double the line amps and you wil have to change the motor overload protection in the starter to the right size also.

An 8 hp 1 phase motor may be hard to find. The price difference between new motor or new transformer would probably be the deciding factor.
 
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