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Quick Three-Phase Motor Coil Connection Question

06/10/2012 3:36 AM

Hello all:

I have a quick question regarding connecting a three phase power supply to the coils of a three phase motor.

Now I know that if you had 3 pole pairs, 6 coils 120 degrees apart around a stator, that each diagonally adjacient coil gets connected in series and each of these series of two coils get connected to one of the three power supply phases. The series coils are shown here:

But what if I wanted 8 coils, 4 coil/pole pairs. How would I connect this to a three phase supply so that the magnetic field rotates dragging the rotor around and around as the motor is supposed to do?

Thanks for any help you guys could give me. I really appreciate it.

Stephen

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#1

Re: Quick Three-phase motor coil connection question

06/10/2012 9:06 AM

With a 3 phase power source I believe you can only directly connect this power source in multiples of 3 pairs of coils with a synchronous induction motor. Now if you change the power source to a true 2 phase power source where the phases are 90° apart instead of 120° apart then one can wire an induction motor using multiples of 2 pairs of coils in a synchronous induction motor. If instead one had a brushed universal motor then one could just use one phase, or convert to DC. If the motor is a bipolar, two coil stepping motor then you must use some driver circuitry between the 3 phase power grid and motor.

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#2

Re: Quick Three-Phase Motor Coil Connection Question

06/10/2012 11:19 PM

It is obvious that you do not know a thing about three phase power and should not try to tackle such problems.

You are not even a fool, . . for even a fool knows that the number of coils on a three phase machine must be divisible by 3.

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#4
In reply to #2

Re: Quick Three-Phase Motor Coil Connection Question

06/10/2012 11:29 PM

NO! A fool hasn't the slightest idea what three phase means, much less how many coils are required. Please don't insult anyone who is trying to learn! Obviously Stephen has much to learn, but he IS trying! Stephen is no fool, because he IS trying!

Stephen:In case you didn't understand from the rude messages, three phase motors MUST have some whole multiple of 3 windings. (3, 6, 9, ...)

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#5
In reply to #4

Re: Quick Three-Phase Motor Coil Connection Question

06/10/2012 11:53 PM

If #420 want to learn - send him to school. You, as a GURU are providing "answers" to these uneducated "specialists" . . and providing answers does not teach an individual anything. The next time he sees the same or a similar problem he will ask you again and again.

Yes #420 has much to learn, . . and so do you . . .

It looks to me like 'phadzi' must be one of your protegees, . . . needs more help than #420.

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#7
In reply to #5

Re: Quick Three-Phase Motor Coil Connection Question

06/11/2012 12:34 AM

"If #420 want to learn - send him to school."

What is CR4, if not a school? People who don't want to learn normally don't ask questions! If no one asked questions, CR4 would not exist!

"providing answers does not teach an individual anything."

If that is the case, then how does one teach? Good students are the ones that DO ask questions, and then ask more, once they understand the answers to the first question.

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#3

Re: Quick Three-Phase Motor Coil Connection Question

06/10/2012 11:22 PM

Simply connect the beginning of each pair together and connect the end of each pair to the one of the phases. The order of phases will only impact the direction of the rotation (clockwise or counterclockwise). To reverse the direction simply replace two phases. This is so called star connection. You can also use triangle connection as follows: connect the beginning of one pair to the ending of the neighboring pair. In this way you get three connection points that you connect to three phases of your supply. Again changing any two phases will change the direction of the rotation. Btw. this rotating magnetic field was invented and patented as an asynchronous electric motor by Nicola Tesla.

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#6

Re: Quick Three-Phase Motor Coil Connection Question

06/11/2012 12:03 AM

Stephen, first take no notice of that out of line & rude comment from that ignorant Canadian, "Olehwi".

The diagram you have shown, proves you are researching your subject and you need a little help.

I would ask you why do you need 4 paired poles, what are you trying to achieve?

It has been state that any windings must be multiples of 3, so having 4 sets of windings doesn't seem to be feasible.

If you did try it, you would have current unbalance on one phase as you have increased the HP of that phase.

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#8

Re: Quick Three-Phase Motor Coil Connection Question

06/11/2012 2:09 AM

wow olehwi how rude can one individual be.......

BY THE WAY I GOT THIS IDEA OF 4 COIL PAIRS FROM A PATENT GIVEN IN 1993. SO IT SEEMS YOU GUYS DO NOT KNOW WHAT YOU ARE TALKING ABOUT!!!

I thought this was a forum to learn and ask questions but I guess its a forum to be called a fool.

JUST SO YOU KNOW I AM A SENIOR AT GA TECH, MAJOR PHYSICS, WITH A 3.9 GPA!!!

AND olehwi IN CASE YOU DON'T KNOW 4.0 GPA IS THE HIGHEST YOU CAN GET SO NO I AM NO FOOL!

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#9

Re: Quick Three-Phase Motor Coil Connection Question

06/11/2012 5:12 AM

Hello Stephen; included you will find an winding drawing for a 8 pole motor 3 phase.

In this motor there are 3 groups from 4 coils in serie. This kind of motor is called a 3 phase 8 pole motor.

As you can see, for each coil, you need at least 2 slots, so for a 8 pole motor you need a least 24 slots.

To understand the winding drawing, I included a 3 phase 2 pole winding drawing, this is the same as your winding drawing in the opening question. Good luck.

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#16
In reply to #9

Re: Quick Three-Phase Motor Coil Connection Question

08/27/2017 2:57 AM

Hello Everyone,

Is the example shown no Post #9 a 3 phase 2 pole winding drawing for Delta Connections?

I have to rewind a 3 phase spindle motor that runs via a delta VFD drive and needed some guidance.

Cheers,

Kafie1980

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#17
In reply to #16

Re: Quick Three-Phase Motor Coil Connection Question

08/27/2017 11:17 AM

Unfortunately, my browser currently shows only blank spaces where the drawings should be in Post #9, and I certainly don't remember what may have been there over five yeas ago. This is curious, as the illustration in the OP is still there...

In any case, a given 3 phase motor will run on either ∆ or Y, as long as the voltage is correct. In fact, there are still many old machines that use ∆ to start gently, then switch to Y for full speed/power.

I've never attempted to rewind any motor (beyond the paperclip motors we made in science class), but I'm pretty sure it requires very specialized equipment and operator knowledge. Send the motor to a professional for rewinding!

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#10

Re: Quick Three-Phase Motor Coil Connection Question

06/11/2012 11:27 AM

How about just using a microprocessor to drive the motor or hall effect senors to determine the voltage needed for each coil pair...

Would that work?

I am using information given to me by my professors concerning motor development that had a stator with 4 coil pairs and a rotor, so I know it can be done, I am just asking how it can be done.

Thanks and I would appreciate real replies not people calling me a fool....

Stephen

A little personal info: I am a current senior at GA Tech, majoring in physics, with a very high GPA and am very interested in researching new ideas and the forces of nature through the inspiration of relativity, electrodynamics, nuclear physics, electrical engineering, quantum mechanics, quantum computing, and basically the whole range of what is considered theoretical physics today. I basically want to bridge some of the gap between Applied physics and Theoretical physics.

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#11
In reply to #10

Re: Quick Three-Phase Motor Coil Connection Question

06/11/2012 12:01 PM

Stephen, when you say '4 coil pairs' I immediately think of a 1200rpm motor as Rudy shows in his post which is very common. Is it 4 pole pairs per phase which would make a 1200rpm machine or 4 coil pairs which would make some sort of zig-zag 3600rpm machine?

Can you include a link for more details on the patent? With more detail we might be able to help.

Rudy, is your top diagram a 4 pole (1800rpm) diagram?

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#13
In reply to #10

Re: Quick Three-Phase Motor Coil Connection Question

06/11/2012 2:50 PM

Yes this can work, but why reinvent the wheel. You've essentially now made your own design of a variable frequency drive that converts a three phase power source into a two phase power source.

There is one thing that nobody has directly asked you yet. What type of a motor is this; Synchronous motor with or without amortisseur windings, induction motor with starter windings, universal motor, stepping, reluctance, hysteresis motor?

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#14
In reply to #10

Re: Quick Three-Phase Motor Coil Connection Question

06/12/2012 11:38 PM

Stephen,

Please do not carry a bad opinion about this site from your single experience . This is an international forum and all sorts of people write and some are very help full some are rude and arrogant but my experience with this forum is that most of the members try to help each other and we learn every day. Remember even Edison was treated badly by his teacher and even called fool when he was in school .

Best of luck in your research work and come out with noble ideas.

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#12

Re: Quick Three-Phase Motor Coil Connection Question

06/11/2012 12:51 PM

Hello Frank; the top diagram is a 8 pole motor 3 phase

included in this reply you find a 4 pole motor 3 phase

If you look at the way the current flows through the coils, and you imagine the magnetical flux lines, you can figure out the poles.

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#15

Re: Quick Three-Phase Motor Coil Connection Question

06/13/2012 8:45 AM

I don't know if the following is helpful or not, I will leave you to decide. The diagrams are for 3 phase control, but it would be really easy to change it to 4 phases. The diagram is taken from the data sheet for the an955 from Microchip.

Here is the diagram:-

You can see just how easy it would be to add an extra transistor pair to another PIC output.....

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Andy Germany (1); brich (1); dkwarner (3); fhadzi (1); frankdolan (1); kafie1980 (1); olehwi (2); redfred (2); rudy.leurs (2); Stephen420 (2); V.I.Abraham (1)

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