3 phase motors how many coils?

K

kjroller

Senior Member
Location
Dawson Mn
Occupation
Master electrician
So I understand that a 9 lead motor is basically a 12 lead motor but 10,11,12 are generally tied internally so you only have 9 leads coming out of the motor. That being said I am wondering if most of these motors contain 12 coils in the stator since they 90% of them are dual voltage. The reason I ask Is in general when you draw a wye or a delta you on paper you generally have six windings, but it doesn't really show you how many coils but generally a winding is made up of 2 coils from what I understand. Also if it was only 9 coils in the stator I don't believe you could have dual voltage because when you try and put the windings in parallel it would be uneven. I would assume a 9 coil would have to be either just high or just low voltage based on what I understand if anyone has any insight, I would be happy to hear it. However I would also believe if you had a 6 lead motor with 6 coils you would be able to go delta for low voltage and wye for high voltage.
 
Secondary question would be If you have 6 windings do you have 12 stator coils or if you have 3 windings do you have 6 stator coils generally do, they corelate with each other?

(For reference I believe coils are what's wrapped around the stator tooth and a winding is 2 of them connected together)
 
kjroller said:
Secondary question would be If you have 6 windings do you have 12 stator coils or if you have 3 windings do you have 6 stator coils generally do, they corelate with each other?

(For reference I believe coils are what's wrapped around the stator tooth and a winding is 2 of them connected together)
Click to expand...
Maybe slots is a better word
 
All three phase induction motors have twelve leads. Three phases, two sets of coils per phase equals six coils. Two ends per each coil equals twelve leads.

Of course there are more than six slots in the stator, but that doesn't matter, the coils in those slots get wired up and spliced inside the motor to get back to six coils which make a set of windings for the north pole and a set for the south pole of the electromagnet that makes the motor spin, and either six or nine of the leads are brought out of the motor and connected to the power.

If it is a nine lead motor you put the windings in series for high voltage and parallel for low voltage. If it is a six lead motor you put the windings in wye for high voltage and delta for low voltage.
 
kjroller said:
(For reference I believe coils are what's wrapped around the stator tooth and a winding is 2 of them connected together)
Click to expand...

Typical induction motor coils are wrapped around much more than a single tooth. The wire follows a path that goes down one slot, loops along the circumference past several slots, up a slot, and along the circumference back to the first slot.

Jonathan
 
I guess the answer to OP question depends on exactly what is being asked. Electrically there is three circuit paths, but likely will have some individual circuit segments that are in parallel to each other, even if only three leads are brought out to the connection box.

Then you have number of magnetic poles in the stator to factor in there. Two and four pole motors are the most common, six pole motors is not totally uncommon, any more than that is kind of a special thing though.
 
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