3 phase to single phase compressor motor?

by Brian
(nazareth, pa. u.s.a)

I have a speedaire 60 gal. compressor that's set up for 3phase with a 5hp motor. I was wondering if I can use a 6hp single phase motor wiht the same rpm's.


The reason for this is I can't find a 5hp with the same shaft diameter. Any help would be greatly appreciated. Thank you, Brian
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Hey Brian, the question is whether I think you can use a 6 HP motor rather than a 5 HP motor on your compressor, given that they have the same RPM rates?

If this were my compressor I would not hesitate to make the change. As long as the RPM is the same then the worst case scenario is that the new motor hasn't got quite the oomph to run the compressor at peak. That may mean a shorter motor life, but I doubt it.

Mind you, to be safe, ( from a motor life standpoint ) if you found a 6 HP 3-P motor with the same shaft diameter then you would have no problems at all.

Other views are welcome.

Bill


Comments for 3 phase to single phase compressor motor?

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May 19, 2013
5hp to 6 hp
by: Buster

Going from a 5 hp 3 ph. to 6 hp single phase will work, just keep in mind that that 6 hp is going to be real hungry for power, the wire size and circuit ampacity is going to have to be upsized to handle the current.
That must be a special 5 hp motor, most are common shaft sizes based on the frame size on the motor. I would do some more shopping before changing to a singe phase motor.
Just a thought,
Buster

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I need a new pressure switch model 3Z921D

by John
(Twin Falls Idaho)

where can I get a pressure switch for my speedaire compressor model 3Z921D 3/4 hp
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I can find no information on this air compressor, John.

What I suggest you do is either start a new thread and upload photos of your switch from all four sides, or remove the switch and take it to a local compressor sales outlet and see if they have an off brand switch that fits, has the same unloader valve hookup, the same voltage, and either the same cut in / cut out settings as the old, or is adjustable.

Cheers,

Bill

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