Counting motor poles

[kevstar]

Hi guys & gals!

Could someone please clarify this for me......

Motor Poles,
I think I am confused. A motor pole is not necessarily one winding is it? If it were then surely a three phase motor can have a minimum of 3 poles not 2 as there is a minimum of three windings inside.

I have a diagram here with a Y connected supply and this is meant to be a 2 pole motor but I cannot understand where the poles start and end!!

Any help would be appreciated.

Thanks

Kev

 

[stardelta]

In simple terms, 2pole means 2poles per phase. Your 3ph motor has 3, 2pole circuits in it, one for each phase. Pole numbers are only divisible by 2. i.e. 2 4 6 8 etc. Increasing the number of poles increases the number of coil groups in each phase circuit and reduces the speed.

 

[SteveKW]

A motor pole is not necessarily one winding is it?
Typically, Yes. A two pole motor has a North winding (group) & South winding (group). And the reason I say typically is there are whats called "consequent pole" motors. Which I doubt you have.

If it were then surely a three phase motor can have a minimum of 3 poles not 2 as there is a minimum of three windings inside.
There is a minimum of SIX in a three phase motor. Three phases, multiplied by two poles, equals six GROUPS.

I have a diagram here with a Y connected supply and this is meant to be a 2 pole motor but I cannot understand where the poles start and end!
Are the leads numbered?
What leads have continuity?

 

[kevstar]

Thanks to both of you for that.

 

[electricpete]

Yup. All correct.

The reason for the terminology 2-pole comes not from looking at the electrical side (how are the windings arranged) but from looking at the magnetic side.

A 2-pole motor has a rotating field with two magentic poles (N and S if you will). We can in theory produce that same type of magnetic pattern with a variety of windings, 3-phase, single-phase (has a forward and reverse rotating field... each two pole)4-phase (if it existed) etc.




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[kevstar]

Thank you to everyone that responded. I nowunderstand a bit more about motor poles and motor theory.

Motors = Extremely complex subject!!!!!!

thanks again it was a great help

Kev