Motor Parts

[Sycorax]

Please have a look at the pics I have attached. It is a motor from a fan at home. I dis assembled it. I am a bit confused of the what the parts are. The one with the shaft( which is circular wheel to it)- is that the armature? And the other part which has copper wires around it , is that the stator with permanent magnets? And this is a brushless DC motor?

 

[desertfox]

Hi Sycorax

Yes the armature is the one with the shaft and the stator is the one with copper wires, could well be a DC motor but I'll let the experts answer that.

 

[ScottyUK]

Standard induction motor. No permanent magnets in there, just silicon iron laminations.

 

[Skogsgurra]

The word "armature" is usually reserved for a DC rotor with windings. Don't use "armature" for the rotor of an induction motor (or PM motor) if you want to avoid confusion.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[waross]

http://www.baldor.com/pdf/manuals/PR2525.pdf

pages 5 to 13.
Probably a split phase motor. If you have a capacitor you didn't tell us about, then it may be a capacitor start motor.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Sycorax]

If you look at the pic, there is a small black box which has a qc-a-17 written on it. Could that be the capacitor you are talking about?

 

[jraef]

Yes, that does look to be a starting capacitor and given the apparent wiring and lack of a centrifugal switch, it is a PSC (permanent Split Capacitor) motor, which fits with it being a small tabletop fan. The only alternative would have been a Shaded Pole motor, in which there would not be anything else attached to the windings, and there would be a copper ring embedded in the steel laminations.

The the purpose of your questions is to get to a point of repairing it, the only possible repair part might be the capacitor unit, but without data on it, you likely will not find it. QC would be just a Quality Control sticker, likely designating the code number for the inspector or production batch. Little fans like this are not designed to be repaired.

"Will work for (the memory of) salami"

 

[theode]

You have a single phase,4 pole,permanent capacitor motor.
Parts showing on pic are end shield,stator (the bit with the windings) capacitor (square plastic box) and the rotor.(The bit that goes round).
There are 2 windings,1 start and 1 run.
Uk speed at 50 hz is around 1450 rpm,US speed 60 hz is around 1600 rpm.
Its not much use other than what it was designed for,in this case,looks like fan duty.
Don't expect any great power out of it,anything too heavy it'll just hum.

 

[Sycorax]

@jraef
The purpose of my question is to understand the motor, its parts etc.. Only for educational purposes. I could not use this table fan as one of the propellers broke and didn't feel like replacing it.

@theode
By looking at the picture how could you say its a 4 pole motor. I couldn't find anything in the pic that's shows its got 4 poles of a magnet.
The copper windings is the electromagnet-is that correct?

 

[Brad1979]

Sycorax,

This is an AC induction motor ... there are no permanent magnets. The rotor is commonly called a "squirrel cage" rotor. It has laminated steel with cast aluminum in the slots of that steel. The rotor won't tell you how many poles there are. On AC induction motors, the number of poles is determined by the winding layout (or, another way to think about it is that the number of poles is determined by which direction current flows through each slot).

It is probably a 4 pole but I wouldn't say that for sure unless you can see the interconnects between each individual coil. It is possible the coils are connected in such a way that would make it a different pole count. That being said, given the number of coils and their width, it is in all likelihood a 4 pole. To be truly sure, you'd have to follow each coil and see how the current would flow through each slot and then see how many poles the current through the slots create.

 

[Brad1979]

Also, the copper windings and steel that surrounds the windings is usually referred to as the "stator." It generally isn't called an "electromagnet" when talking about a motor.

 

[theode]

If you look at the stator from above,you will make out 4 sets of coils on the edges of the square shape.
That is the run winding.
There is another set of 4 coils at the corners of the square shape,that is the start winding.
They are connected to give a polarity of north pole,south pole,north pole,south pole.
Hence a 4 pole motor.
The more pairs of poles,the slower the motor.
Motors are a complicated subject when you start to look into it and trying to explain to a non motor person is quite difficult.
Hope this helps.

 

[Brad1979]

theode,

As I said, you are probably right. But you said "They are connected to give a polarity of north pole,south pole,north pole,south pole." How can you see that from the picture? You can't. How each individual coil is connected to each other is unknown at this point. The most probable way is that each phase is connected in series just as you said but it isn't necessarily the case. The number of coils (per phase) is not always equal to the number of poles.

 

[theode]

I was trying to give a simple explanation to sycorax's question.
Yes,there are various permutations of connections regarding polarity.These are used more on 3 phase units rather than 1 phase.
That wasn't the question.
The basis of the pictured stator is 4 pole.
To vary from this speed would require tappings in each coil winding to make a variable resistance.
I am trusting 45 years experience of repairing motors like that,to tell me its a 4 pole.
I'm sure you'll tell me if I'm wrong.

 

[Brad1979]

Like I said (twice already), you are probably right. It is very common for 4 coils per phase like this to be used to create 4 poles. All I'm saying is that this is not the case in general and one shouldn't confuse the number of coils per phase with the number of poles. What determines the number of poles is how the current in the slots sets up the magnetic field.

 

[waross]

It is possible the coils are connected in such a way that would make it a different pole count. That being said, given the number of coils and their width, it is in all likelihood a 4 pole.
If the motor shown were to be connected as anything but a four pole motor it would not work properly.
Motor coils which may be successfully reconnected for different numbers of poles are generally overlapped.
There is not enough space between the edges of the coils to allow good operation as a subsequent pole motor.
Listen to 45 years of experience.
That is a 4 pole motor, no probably involved.

Bill
--------------------
"Why not the best?"
Jimmy Carter