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3 phase to single phase!!!!

truthseeker

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Joined
Jan 2, 2008
Messages
2
I bought a air compressor that has a 3 phase motor and I only have single phase at my home. Is there a way to run a smaller motor to start the 3 phase motor and then run it off of single phase power? If not can you give mw some suggestions. Thanks!
 
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locoman

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Sep 16, 2007
Messages
97
No. You will have to get a single phase motor. Most situations like this want to go the other way, single to three. Find someone to trade your motor with.
 

Franz©

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Mar 26, 2006
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in a house
Compressors are among the hardest machines to drive, so the idea of a starter motor rotating the machine and single phasing the compressor drive will let magic smoke out of the compressor motor real quick.

If this will be your only 3Ø load the most cost effective solution will be a variable frequency drive assisted by an unloader that will allow the machine to come up to speed freerolling.
If your air demand will require multiple starts in a 10 minute period switch the machine over to constant run and employ a VFD to power it.
 

W-Cummins

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Jan 9, 2006
Messages
1,639
Location
Iowa
Unless the motor is over 7.5 hp your going to be better off swapping in a single phase motor for the 3 phase motor. You will probably never find some one to trade you a single phase motor for a 3 phase one esp. in the 5-7.5 hp range as the single phase motors are way more $$$ than the 3 phase stuff. IF I needed a 5hp 3phase used motor I would pay at most 50 for it. A good used single phase compressor duty 5hp motor is worth 2-4 times that. Now if your at the 10hp level, the swap to a single phase motor VS a VFD drive is about a wash. A VFD that will run a hard starting application like a compressor @ 10hp on single phase will be 800-1000, and the motor will be about $800+ new. How big of a compressor motor are we talking about??

William....
 
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Tscott

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Oct 17, 2006
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1,484
Location
Keystone Heights, FL.
Here is a link to just 1 of 18 motors I found on the Grainger website.

http://www.grainger.com/Grainger/items/6K847

I would just change the motor out. a 5hp is an easy swap and would be almost a bolt in type deal. These just make sure you get the appropriate motor for the rpm and powerr you need and put the appropriate size cord on it.

Tom
 
Last edited:

roadking778

Member
Joined
Dec 27, 2007
Messages
13
Location
Western Kentucky
I have installed a phase converter before and I guarantee you it will be cheaper to change the motor on the compressor. If you plan on buying more equipment that runs on three phase then you should consider the converter, if not swap it out.
 

toxicz28

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Sep 23, 2006
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738
Location
NY
A buddy of mine runs a machine shop out of his house. He uses rotary phase converters, and says it is cheaper in the long run to use a phase converter.
 
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