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Wiring Winding Single Phase Motor

11/07/2017 4:40 AM

I have a electrical motor with 6 windings . I need to reconnect the windings to have a singel phase 4 pole capacitor start and capacitor run motor

I will attach photos of the motor windings 123456 and the ohm readings of each winding.

could you help me out with this project.

Thank you

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#1

Re: Wiring Winding Single Phase Motor

11/07/2017 10:20 AM
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#3
In reply to #1

Re: Wiring Winding Single Phase Motor

11/07/2017 3:01 PM

The voltage is 240v 2.5 HP

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#4
In reply to #3

Re: Wiring Winding Single Phase Motor

11/07/2017 3:48 PM

Was this always single phase, or are you attempting to shift one from 3 phase to single phase?

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#5
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Re: Wiring Winding Single Phase Motor

11/07/2017 4:25 PM

I am shifting a 3 phase motor to a 4 pole cap run cap start singel phase motor

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#2

Re: Wiring Winding Single Phase Motor

11/07/2017 11:53 AM

Why?

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#14
In reply to #2

Re: Wiring Winding Single Phase Motor

11/08/2017 10:53 AM

Why not? Every shop needs a good fire now and then.

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#6

Re: Wiring Winding Single Phase Motor

11/07/2017 4:33 PM

If I were you... I would take it to a motor rewind shop, tell them what and how it was connected and at what voltages and phases and what you want it changed to and they will tell you if it is possible or not. But... that is just what I would do.

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#7
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Re: Wiring Winding Single Phase Motor

11/07/2017 4:49 PM

North: you forgot to tell this fellow, that you are very wise indeed.

That is what a wise person would do, but perhaps our friend is strapped for cash. I have no clue the best answer for him on this, except as Solar Eagle suggested.

Look at wiring diagrams for as many motors as you can until you find a match, and then match what you want the motor to be, and switch the windings around, and pray.

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#10
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Re: Wiring Winding Single Phase Motor

11/07/2017 4:58 PM

To take the motor to rewind is expensive which I do not have I thaught this could be done.

i have been on you tube that gives advice . I was hoping to change the motor into a singel phase.

if this can not be done then how do I make a singel phase convertor to 3 phase supply to run this motor.

if there is no other way.

Greg

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#8

Re: Wiring Winding Single Phase Motor

11/07/2017 4:49 PM
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#9

Re: Wiring Winding Single Phase Motor

11/07/2017 4:56 PM

You're going to need to know the positional relationship of each coil so that you can create a rotating magnetic field.

The run windings will be located farthest from the rotor and may or may not be of a larger gauge wire (your resistances are too close to confirm a differing gauge). The start windings will be closest to the rotor and will be located within the poles of the run windings, ie. the outer run windings will overlap the inner start windings. A close look at the stator should tell you which are the start and which are the run windings, and their sequential relationship with each other.

For the motor to run correctly, you must ensure that all start and all run coils are connected in the right sequence going around the stator ie, out of run coil 1 to in of run coil 2, out of run 2 to in of run 3, and the same for the start winding. It doesn't matter which coil of the set you begin with provided you continue around the stator in order and get the ins and out right. You should be able to determine the in/out relationship by looking at the way the coils are wound. If you do not get this right (say one coil reversed) the motor will run slowly, or not at all, and overheat.

Then you bring the in of run 1 and the out of run 3 to the terminal block, and the same for the start winding, these become your winding connections.

The actual connection relationship between start and run at the terminal block is unimportant as that will simply determine direction of rotation.

As the resistances are so close, you can likely use either set for start or run with no ill effects, and you can choose rotation by in which set you place the capacitors without the need to reverse one of the winding sets.

Hope this helps.

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#11
In reply to #9

Re: Wiring Winding Single Phase Motor

11/07/2017 5:08 PM

Could you supply me with a drawing of the your preferred layout.This will help me

This is what I am looking for.

Greg

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#12
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Re: Wiring Winding Single Phase Motor

11/07/2017 6:33 PM

My apologies. I didn't read your original post correctly and assumed this was originally a single phase motor. Your post #10 made me realise my error.

Please disregard the info I provided as it will not be relevant to your situation.

You may be better off to purchase a suitable single phase unit.

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#13

Re: Wiring Winding Single Phase Motor

11/08/2017 10:07 AM

Look... if you cannot afford to take the motor to a re-wind shop for advice on whether or not this motor can be changed to fix your needs, then there is certainly no way you can afford to "build" a single phase to three phase converter.

The cheapest way to get this going is to... give up on playing with this old motor and go buy a proper one for the application and the power source you have available to run it.

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#15
In reply to #13

Re: Wiring Winding Single Phase Motor

11/09/2017 4:51 AM

I am not happy with the 3 phase motor .I have decided to remove all the windings and rewind the motor.
The motor I require is a singel phase motor.2.5 Hp 4 pole 2500 RPM If it can be done Cap start cap run.
The motor has 36 slots.
I require help with the wirer size and the winding sequence.and connections forward and reverse
I realise that there could be 2 different wirer sizes.
For run and start.
This motor I will use on my milling machine as the motor is flang mounted.
I only have singel phase to the shed.240 AC VOLTS
I would apperiate all the help I can get as I do not have the money to replace it with a new one.
I am prepared to have a go. And learn.
The question will be asked what happened to the original motor.
I baught it very cheep as I can not afford a new one. The miller did not have a main motor.
This one was given to me as a 3 phase .
I need Singel phase.

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#16
In reply to #15

Re: Wiring Winding Single Phase Motor

11/09/2017 6:38 AM

I gotta say I admire your tenacity but this exercise is likely to end in disaster with the only lesson being not to try it again. Save your enthusiasm for a winnable endeavour.

Rewinding a motor is not for the uninitiated. One wrong move (and that's really easy to do) fitting the coils into the stator and you will have major failure. Incorrect number of turns and you have another. Both mean starting over from scratch.

By the time you purchase the correct wire plus starting gear (it's going to have to be external as the existing motor won't have any provision for that) plus capacitors and other bits, you would more than likely get yourself a reasonably priced new or even second hand one for very little extra cash.

A 2.5hp single phase motor will be larger than an equivalent 3 phase one. Do you know the hp rating of the motor you have, is it even big enough to rebuild into a 2.5hp single phase one even if you could manage it.

Making the existing motor run on single phase with a phantom leg will likely result in low power and torque and a VFD will set you back even more dollars than a new motor

You have had plenty of advice, make what you will of it. I wish you luck.

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#18
In reply to #16

Re: Wiring Winding Single Phase Motor

11/09/2017 10:13 AM

Yes, much can be said for picking your battles, and your ground very carefully.

This is no hill to die on.

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#17

Re: Wiring Winding Single Phase Motor

11/09/2017 8:48 AM

Here are my last comments on this thread.

As a safety regulator, I need to let you know that what you are proposing to do is fraught with the potential for error, is more than likely illegal in any jurisdiction that has any sort of proper regulatory regime in place for electrical installations (definitely so for North America) and finally, if this things causes a fire, it will be found out that the motor was rewound by you and any insurance coverage in place would be more than likely voided.

I understand the fiscal issues, however, the rules around electrical equipment are in place for valid reasons.

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#19

Re: Wiring Winding Single Phase Motor

11/09/2017 11:24 AM

You may find yourself much better off to find on line a single phase to three phase VFD. Then the motor stays intact and you can regulate it to whatever rpm you want. The last one I bought was 3.1 kw and cost about $160. Christmas is coming...

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#20

Re: Wiring Winding Single Phase Motor

11/09/2017 2:19 PM

Gregory,

You will spend less time earning enough money to buy what you want than you would spend trying to make this thing work for more than a few minutes. There are literally thousands of motor designs which includes all sorts of variation. I suspect that your time is more valuable than the futility of your conquest. After all, the rotor is also part of the consideration and you gave us nothing to work with on the rotor.

Secondly the geometry of your frame makes it impossible to get the number of poles you requested. You need a coil for each end of the rotor. For a four pole single phase design, you need 8 coils. The last time I checked, 36 divided by 8 was not a whole number. That is the first problem. If you don't mind it running really slow, you might be able to turn it into an 18 pole motor, but then you have to make more room for the extra wire. As someone already mentioned, single phase motors of a given power level are larger than three phase motors.

An 18 pole, single phase motor will have a design speed (at 60 Hz) of 3600/18 = 200 RPM minus slippage. I don't think that is what you intended either. Ultimately, there are something like 20 variables used in designing magnetic circuits including clearance between parts that rotate and parts that don't move. The quality of your bearings may not be sufficient for single phase operation unless 200 RPM is your goal. "The Force" is just not with you on this one. Find something better to do with your time because time is something you can never get back.

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