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Discussion Starter · #1 ·
Hey boys, buddy of mine is looking at buying a jointer from an auction that has a 2 phase 5 hp motor. I know nothing about 2 phase aside from what I've read here. His shop has a single phase service and a homemade RPC for his 3 phase power. Is there anyway to run a 2 phase motor on either one of those supplies. Changing the motor isn't an option. I suppose it could be rewound if necessary. Thanks guys.
 

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A 2-phase motor?

How old is this thing?

Are you sure?
 

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Discussion Starter · #3 ·
I thought the same thing but ya I looked at the auction listing and they made a note of it specifically. If say the machine is from the 40's. plus it's out of Pennsylvania where as I understand it they still use 2 phase systems in older buildings.
 

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Electric Al
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Hey boys, buddy of mine is looking at buying a jointer from an auction that has a 2 phase 5 hp motor. I know nothing about 2 phase aside from what I've read here. His shop has a single phase service and a homemade RPC for his 3 phase power. Is there anyway to run a 2 phase motor on either one of those supplies. Changing the motor isn't an option. I suppose it could be rewound if necessary. Thanks guys.

2 phase ? --- 2 hots , no neutral ? :001_huh:

Please explain .

What voltage ?
 

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I thought the same thing but ya I looked at the auction listing and they made a note of it specifically. If say the machine is from the 40's. plus it's out of Pennsylvania where as I understand it they still use 2 phase systems in older buildings.
Well if that's the case I think there's a way to rig up transformers to get 2-phase out of 3-phase, but I don't think it'd work for single-phase. I don't have the foggiest idea how to do that anyway.

Why is putting in a different motor not an option?
 

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Discussion Starter · #6 ·
oldtimer said:
2 phase ? --- 2 hots , no neutral ? :001_huh:

Please explain .

What voltage ?
From what I understand its 4 hots sorta like a double polyphase system.
 

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Discussion Starter · #7 ·
erics37 said:
Well if that's the case I think there's a way to rig up transformers to get 2-phase out of 3-phase, but I don't think it'd work for single-phase. I don't have the foggiest idea how to do that anyway.

Why is putting in a different motor not an option?
Ya I saw something called the "Scott system" trying to understand how I can make this work without a custom made transformer. 3 phase is available off the RPC.

In the case of a different motor. The motor is a custom motor built right into the machine. Plus I would imagine its a high speed motor as its direct drive right to the cutter head and those cutter heads need to turn at around 5500 rpm
 

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Like the other guys said, you need a Scott connection transformer. It has four windings: Two high windings that are "T" connected that you would hook your 3Ø up to, and two independent low windings that are 90° out of phase with each other.

If this really is a 2Ø motor you'd hook it up to the 4 wire low side and it would work.

I've never had to gang a Scott connection, but thinking out loud here, it might be possible to build one out of a couple of single-phase transformers that had center winding taps and it could save you some money over buying one. Someone will have to double check me on that.

But personally, I'd just buy a new 3Ø 5HP motor.
 

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Rather than convert from single phase, to three phase, and back to two phase, it seems like changing to a new, single phase 240v 5hp motor would be the simplest, most reliable and most energy efficient option if you could get it to physically fit.
 

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Discussion Starter · #15 ·
Vintage Sounds said:
Rather than convert from single phase, to three phase, and back to two phase, it seems like changing to a new, single phase 240v 5hp motor would be the simplest, most reliable and most energy efficient option if you could get it to physically fit.
That's not an option
 

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Discussion Starter · #17 ·
Because its a custom mount designed for that specific machine and it's a high speed motor
 
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