[Neanderthal]

Well, I posted this over on the electrical forum and I guess I didn't look at the rules close enough! Oops . . . .
60 year old noob here. A lifetime of mechanical knowledge, but AC motors . . . not so much. I basically inherited this motor on a vertical air compressor. No capacitor, four wires, and out of a shop that had no 440, this must be a 220 three phase motor. Am I right so far? I can see on the nameplate what I believe to be HP (5), RPM (1725) and not much else makes a lot of sense to me. Of course, I have single phase in my shop. Is there a practical way to wire this puppy up? As in a static or rotary phase converter? The compressor is worth maybe $1000, so I must keep that in mind. I am looking for thoughts, advise, experience, etc. Any contributions will be deeply appreciated.

 

[Neanderthal]

Well, I posted this over on the electrical forum and I guess I didn't look at the rules close enough! Oops . . . .
60 year old noob here. A lifetime of mechanical knowledge, but AC motors . . . not so much. I basically inherited this motor on a vertical air compressor. No capacitor, four wires, and out of a shop that had no 440, this must be a 220 three phase motor. Am I right so far?
I can see on the nameplate what I believe to be HP (5), RPM (1725) and not much else makes a lot of sense to me. Of course, I have single phase in my shop. Is there a practical way to wire this puppy up? As in a static or rotary phase converter?
The compressor is worth maybe $1000, so I must keep that in mind. I am looking for thoughts, advise, experience, etc. Any contributions will be deeply appreciated.

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[micromind]

That motor is indeed 3 phase and it is connected for 230 volts.

There are 2 ways to make it run on single phase;

1) Phase converter. There are 2 types, static and rotary. Static is by far less $$$ but it'll run a 3 Ø motor at about 60 - 70% or its rating. Also, starting torque is very low. Not a good choice for an air compressor. The other type is rotary. This will get about 80 - 90% of the motor rating and starting torque is moderate. If you go this route, get a pulley for the motor that's a size or two smaller.

2) VFD (Variable Frequency Drive). This unit can convert single phase to 3 Ø and vary the speed. Its starting torque is not as good an with normal power but it'll start an air compressor ok. It also requires programming in order to operate. At 5HP, be careful that it will accept single phase input.

Trouble is, both of these options are likely more $$$ than a 5HP single phase motor.

The motor shown is a 215 frame.....non-standard. This means that your average everyday 5HP single phase motor will have a different shaft size and different mounting hole locations.

A word of caution; there are a LOT of '5HP' single phase compressor motors out there that are not 5HP at all. They're more like 2 - 3HP. They get away with advertising them as 5HP because that is the peak HP they will produce, not continuous HP.

The best 5HP single phase motors will be 184T frame. The shaft will be 1 - 1/8 diameter and the mounting holes will be 5 - 1/2" X 7 - 1/2". 5HP motors that are 56 frame are not very good and are likely the ones referred to above.

Rob

 

[Neanderthal]

Thank you Rob!
Quick look at eBay. About $350.00 for what looks to be a decent motor: http://www.ebay.com/itm/5-HP-Single...199307?hash=item3aaff5698b:g:PLMAAOSw3KFWc4Z~
Of course it's not just going to bolt on . . . . .
And lots of Chineseum variable frequency drives. Never heard of such a thing until today. That is the great thing about the interwebs. Lots of smart people!
Any brand recommendation if I go the variable frequency route?

 

[micromind]

Stay away from the cheap VFDs, they don't last very long.

Coming from an industrial environment, my favorite brands are Allen Bradley and Baldor. I've installed quite a few of them over the years and never had a problem with any. They don't exactly give them away though......lol.

My favorite motor brands are Leeson and Baldor.

The motor in the ebay link will work.

Mounting base adapters are available, one model is from mscdirect.com part #00573055. It'll bolt to the original holes and the new motor will bolt to it.

 

[York v45]

Look at the right hand side of the dataplate. There is a diagram for "High Voltage" and "Low Voltage". From the diagrams it appears to be a standard 3 phase 9 lead motor. If so, it will not run on single phase and you will need a phase converter. You will have to weight the cost of a phase converter against the cost of a single phase motor.