2 speed12 coil motor - 2 or 4 poles?

C

carlos290

Member
Location
Portugal
Occupation
Rewinder
Hi,
I've a motor with 12 coils in it, it came without any info on it, and a very destroyed winding, but i could get the following from the coils wiring:


ibb.co

Screenshot-2024-12-19-at-21-54-51 hosted at ImgBB

Image Screenshot-2024-12-19-at-21-54-51 hosted in ImgBB
ibb.co ibb.co
(cant upload image here, sorry)

does this makes sense to be a 2 and 4 poles?

thanks

ps: im in europe, this is a 400V, 50hz
 
Welcome to the forum.

It's a 3ph motor with 12 coils. So, you have four sets of three coils, or four poles.

1734647114016.png
 
What is the span of the coils in the stator?

How many slots total around the circumference of the stator?

How many slots from one coil half to the next (count the first coil half as slot zero, and say the number of the second coil half)?
 
winnie said:
What is the span of the coils in the stator?

How many slots total around the circumference of the stator?

How many slots from one coil half to the next (count the first coil half as slot zero, and say the number of the second coil half)?
Click to expand...
Span: 1-5-7-9-11

48 slots

5
 
Things aren't adding up. If you have a 48 slot stator with only 12 coils, then half of the slots would be empty.

Can you clarify the span. Do you have a concentric winding where you have a span 5 coil surrounded by a span 7 coil surrounded by 9 then 11?

My current guess is that you have a machine with a 4/8 'consequent pole' winding, but I would not count that as more than a guess without more details.

Jonathan
 
maybe is my english :)

every coil fills half of the slot (don't know how you say it there), so : 12 coils x 8 (number of slots each coil occupies) = 96 / 2 = 48 (number of slots)


Can you clarify the span. Do you have a concentric winding where you have a span 5 coil surrounded by a span 7 coil surrounded by 9 then 11?
Click to expand...

yes, it is concentric. and yes for the span question
 
Okay, it has been decades since I looked at windings for consequent pole machines, so my answer could be _very_ wrong.

You have 12 'pole phase groups', and I was confused because you called each group a 'coil'. I would say each group has 4 coils, but as long as we understand it is fine to call a 'pole phase group' a coil.

Groups 1, 4, 7, and 10 are all part of the U phase. 2,5,8, and 11 are V, and 3,6,9, and 12 are W.

In one mode you supply power to U1, V1, and W1, and short U2, V2, and W2 together. U2, V2, and W2 form a star point parallel to the permanent star point in the motor. In this mode groups 1 and 7 have the opposite polarity from 4 and 10, and 1, 7, 4 and 10 are all see the full L-N voltage. At a given moment in time, when group 1 is N, group 4 is S, group 7 is N and group 10 is S. In this mode you would operate as a 4 pole machine.

In the other mode you leave U1, V1, and W1 open, and supply power to U2, V2, and W2. Trace the current flow from U2; you go through group 4 and 10, then to the U1 node (not connected to anything) then through groups 1 and 7. On this path, the 'sense' of current flow through all the coils is the same, at a given moment in time, when group 1 is N, group 4 is N, group 7 is N and group 10 is N. In this mode each coil sees half of the L-N voltage, and the machine operates as an 8 pole machine. This is called 'consequent pole' operation; when group 1 and group 4 are both N, there must be an S pole in the gap between them.

Hope this helps. Like I said I've not worked with this for decades, so take the above with a grain of salt and see if it helps you get a self consistent understanding.

Jonathan
 
winnie said:
Okay, it has been decades since I looked at windings for consequent pole machines, so my answer could be _very_ wrong.

You have 12 'pole phase groups', and I was confused because you called each group a 'coil'. I would say each group has 4 coils, but as long as we understand it is fine to call a 'pole phase group' a coil.

Groups 1, 4, 7, and 10 are all part of the U phase. 2,5,8, and 11 are V, and 3,6,9, and 12 are W.

In one mode you supply power to U1, V1, and W1, and short U2, V2, and W2 together. U2, V2, and W2 form a star point parallel to the permanent star point in the motor. In this mode groups 1 and 7 have the opposite polarity from 4 and 10, and 1, 7, 4 and 10 are all see the full L-N voltage. At a given moment in time, when group 1 is N, group 4 is S, group 7 is N and group 10 is S. In this mode you would operate as a 4 pole machine.

In the other mode you leave U1, V1, and W1 open, and supply power to U2, V2, and W2. Trace the current flow from U2; you go through group 4 and 10, then to the U1 node (not connected to anything) then through groups 1 and 7. On this path, the 'sense' of current flow through all the coils is the same, at a given moment in time, when group 1 is N, group 4 is N, group 7 is N and group 10 is N. In this mode each coil sees half of the L-N voltage, and the machine operates as an 8 pole machine. This is called 'consequent pole' operation; when group 1 and group 4 are both N, there must be an S pole in the gap between them.

Hope this helps. Like I said I've not worked with this for decades, so take the above with a grain of salt and see if it helps you get a self consistent understanding.

Jonathan
Click to expand...
Thank you!
 
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