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View Full Version : Coolant Pump 3-ph to 1-ph with Capacitors



electrosteam
5th Apr 2017, 06:01 PM
I have 2 off ex-industrial ex-auction 3-ph 415/240 Vac good brand coolant pumps 1/8 hp.
Each tests ok for continuity and insulation and will run on 1-ph 240 Vac once spun by hand.

Can anyone please confirm that it is worth the cost and fuss of adding appropriate capacitors to install them on a machine tool, as compared to scrapping or selling and purchasing new 1-ph units ?

John

BobL
5th Apr 2017, 06:51 PM
It depends on what sort of a load the motor is under. Under light load it might be worth it, but if they are working above about 50% of their HP rating they will overheat.
You can get a crude check of the HP by seeing how much current they draw and using say a 60% efficient rating for a small motor.

A back of the envelope calc - someone else please check

The nominal input power @ 1/8 HP and 60% efficiency would be 745/8/.6 = 155 W

On 240V that would make it 650 mA

If it draws more than 350 - 400mA I would be wary of using it.
If you do use it you might want to run it and monitor temps before you set and forget.

Rather than purchasing a new SP motor and go though the headache of fitting it might be easier and cheaper to purchase a small used VFD , then you could control coolant flow through pump speed.

I have a beautiful fully SS closed loop coolant pump I want to set up for a water cooled TIG torch. It has a 1/8 3P motor on it and I will be fitting a VFD to it.