Electric motor help

[muddevil01]

Hello all I am new here so if this post is in the wrong location I alpologize. I recently picked up an electric motor for free to use on an air compressor project. The problem is there are no markings on it at all I am fairly certain it is 220v due to it's size. How do I tell if it is single phase or not? I don't have pictures of it I will try to get some. Thanks in advance

 

[Cmreschke]

Single phase will have 2 termination points, three phase will have 3 termination points.

 

[damienga15de]

Single phase Will have 3 termination points, 3 phase will have 7

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[930dreamer]

Single phase will have a round cover attached to the case that houses a start capacitor.

 

[larry_g]

As your investigating see if any of the wires that come from the motor have number taga or numbers printed on them. If there is a set of numbered wires then we can make a better guess at what you have . The above post are some what correct but not the bottom line as there are many different motors out there and lots of different wiring schemes. The size of the motor case has nothing to do with what the voltage may be.

frame sizes

connection diagrams



lg
no neat sig line

 

[LS6 Tommy]

Single phase will have 2 termination points, three phase will have 3 termination points.

Single phase Will have 3 termination points, 3 phase will have 7

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Single phase will have a round cover attached to the case that houses a start capacitor.

The number of termination points doesn't have anything to do with identifying single or three phase. It's the way they're terminated to each other that ID's a motor as single or three phase. A single phase motor can have LOTS of terminals, depending on if it's multiple voltage, multiple speed, reversible, etc. Not knowing one from another will not allow you to ID just by the number of terminals.

Three phase motors can have many terminals too, depending on whether they're multiple voltage, part wind start, etc.

Not all single phase motors have caps. Only if it's a cap start (CSIR), cap start/run (CSCR) or run cap (PSC) motor. Split phase (RSIR), shaded pole and repulsion motors do not.

Post a picture or two of what's inside the terminal box if you can.

Tommy

 

[Freejack]

If the nameplate is no longer on the motor, please post both a picture of the motor and the connections inside the termal box.

Jake

 

[nehog]

Post a picture of the motor, and the wires coming out of it.

 

[muddevil01]

Ok thanks guys I will try to get some pics. I work nights so my schedule is a bit weird thanks for the info

 

[G_P]

Where did you get the motor? If it came from a factory or other industrial setting its likely 3 phase.

Look it over very carefully. There is probably a data tag or sticker on it and it has been painted over. Hopefully under the cover where the wires come in, there will be a wiring diagram showing how to wire it and what voltages it can be run on.

 

[muddevil01]

Here are some pics it has 7 wires terminated into 3 thanks in advance

 

[ratman2]

Here are some pics it has 7 wires terminated into 3 thanks in advance

That looks like a 3 Phase motor to me

 

[woodzie]

3 phase for sure.

 

[LS6 Tommy]

It's three phase, wired for low voltage (wye). It's most likely a 230/460V motor...

Tommy

 

[G_P]

I would say that's a 3 phase motor you have. With the data plate scrubbed clean you cant even really sell it since you dont even know what HP it really is.

 

[RogueFab]

yup. 3 phase. And old. Looks like around 1 hp based on the size. You can run it on house current 220v, you just need to wire it up correctly and get a static phase converter (about $60) for the third phase.

You can use an amp meter to determine the HP (or get close) once you get it running with a load on it.

Only tough thing is getting the leads figured out. A resistance meter will tell you how long the windings are relative to each other, but not what order they are in around the motor.

 

[RogueFab]

It is wired for 240V already. The motor has 6 windings, 3 pairs that are 120 degrees apart (for a total of 360 of course). One phase of power makes the magnetic field at each position in order to generate the torque. Now those pairs are wired in series for high voltage, and parallel for low voltage. So you will have 3 separate junctions with no power input wires and 3 more with power input wires for 480V. For 240 volt, you will have one group taped, and 3 larger groups for the power input wires. The diagram should help:

Get a static converter and let us know what the loaded current is. I bet its around 5 amps... 1HP for a moderately loaded 1hp @ 220-240.

 

[James-W]

How big of a compressor are you planning on running with this motor?

 

[muddevil01]

It is a 90 gallon 2 stage the reason I was considering using this motor is that it was free so I think I might start looking for a different motor

 

[LS6 Tommy]

It is wired for 240V already. The motor has 6 windings, 3 pairs that are 120 degrees apart (for a total of 360 of course). One phase of power makes the magnetic field at each position in order to generate the torque. Now those pairs are wired in series for high voltage, and parallel for low voltage. So you will have 3 separate junctions with no power input wires and 3 more with power input wires for 480V. For 240 volt, you will have one group taped, and 3 larger groups for the power input wires. The diagram should help:

Well put! I wasn't going to get that technical, but you nailed it! And, yes, I realize I typed it was wired for 230VAC. It wasn't a typo. I'm used to going by nameplate ratings.


Tommy

 

[PT Doc]

Likely very undersized motor for your intended application.

 

[bisley45]

If you could get me some pictures of the end bells of that motor I might be able to Id it for you. I do know that it is a Delta motor for sure but it still might be a single phase motor but repulsion induction motor. Here is what the tag most likely looked like.

 

[RogueFab]

Well put! I wasn't going to get that technical, but you nailed it! And, yes, I realize I typed it was wired for 230VAC. It wasn't a typo. I'm used to going by nameplate ratings.


Tommy

Thanks. I consider 220/230/240 to all be names for the same thing. I wasnt trying to correct you. As long as it's not 208

And you might have a decent motor for the aplication. How much does it weigh? That can tell us a lot. 1hp ain't gonna cut it on that pump...

 

[muddevil01]

I'm not sure what it weighs but it is HEAVY I will try tp get some pics of the ends will that work?

 

[ffast65]

I have a double ended version of that that's 120v single phase.
Was my grandpas before he died 9 years ago.
Roof leaked destroying the tag on mine too tho.

Mine has a switch in the junction box with an cord coming out.

 

[ffast65]

Found another real nice one of these today. Must have been indoors all these years but unfortunately was 3 phase 1140 rpm 3/4 HP. Model Y9452B

Unless internally it can be swapped to single phase, it will stay at the scrap yard.

 

[wyliesdiesels]

3/4hp is too small for your compressor and no motors cant be readily changed internally to single phase....back to the scrap yard...

 

[ffast65]

Yep, I didnt take it for just that reason even though I have a single phase one of the same motor. Just offered nothing to me

I use my single phave for buffing and the tag is rusty but its 1750.