How to tell how many poles a motor has.
How to tell how many poles a motor has.
(OP)
Hi just wanting to find information on electric motors and how to tell how many poles a motor has. Im being trained on winding motors but at present cant get my head around how to tell how many poles inside a motor. Anyone any interactive showings of how to tell? I know its each change in the windings results in a pole, ie each up and down, but I just dont get how to see it inside the motor before stripping it, any tips are greatly appreciated or if theres any books or photos of the inside of motors to show different poles and windings that would be great as well.
Thanks Alan
Thanks Alan





RE: How to tell how many poles a motor has.
I'm guessing you already knew that. By looking at the connection end, you can figure out how many parallels (start at a phase lead and see how many different coils connect directly to it. I guess there's a lot more an experienced winder can tell looking at the endwindings. For me I usually end up confusing myself.
=====================================
(2B)+(2B)' ?
RE: How to tell how many poles a motor has.
A two pole single phase induction motor has 4 windings, and a two pole three phase motor has 6 windings.
But if you are looking at DC motors that may be totally different.
RE: How to tell how many poles a motor has.
i.e. a 2-pole 3-phase motor has 6 “pole-phase groups” or simply six “groups”. Coils within a single group are both physically and electrically adjacent.
For 3-phase motors, the term “winding” usuallly refers to the complete set of all coils in a stator…. The stator winding.
=====================================
(2B)+(2B)' ?
RE: How to tell how many poles a motor has.
Thanks alan
RE: How to tell how many poles a motor has.
Like pete sayd the poles depends of speed and frequency.
IMO you want to know how connect a winding to get a determinate pole number. This depends of experience and is a hard issue, so could be good that you play attention to your collegue and read some basic books or guides about winding motor. One excellent could be founded in http://www.easa.com/software/HowToWindThreePhaseSt....
Regards
Carlos
RE: How to tell how many poles a motor has.
The inter-coil jumpers within a group are the same for all groups. For example connect top lead of one coil to bottom lead of the next coil CW.
The polarity of physically adjacent coil groups must alternate (N/S/N/S etc). That must be considered in connecting the jumpers between poles. Assuming there is only one circuit per phase, the simplest way is adjacent pole connection. See here for that thread237-281260: 1-long jumper 360-deg or 300deg... 2-ôskip groupö?
The powerpoint attached there (adjacent pole) gives an idea of typical pole jumpers. When you look at those pole jumpers in the adjacent pole connection, you’ll see they go either top to top or bottom to bottom (they don’t go top to bottom or bottom to top for adjacent pole connection with short jumpers).
Lots of complications and variations possible. The groups in a phase are not always connected in one series path. Sometimes there are multiple parallel paths, per phase, each referred to as a “circuit”. A two-circuit winding has two parallels per phase.
If I were studying a winding, I would START with the nameplate to determine the nuimber of poles, then look at the winding itself to try to get additional details. There are plenty of the forum that spend a lot more time with windings than me.
I agree 100% with petronilla to get some good training. Unfortunately the site mentioned in the linked thread (uiitraining) no longer exists. I don’t know of any good free training materials. Maybe forum member zlatkodo has some info on his site? (if not, that might be a good marketing tool to get more people to your site… I’d link to it!). As far as books, Rosenberg’s book is often mentioned as a rewinder’s bible but it’s somewhat old and not laid out for beginners. EASA is the trade organization for motor shops in the US. You definitely can’t go wrong with their training materials if you can afford them.
=====================================
(2B)+(2B)' ?
RE: How to tell how many poles a motor has.
Thanks Alan.
RE: How to tell how many poles a motor has.
- In most cases, an experienced technician will immediately recognize the winding, thanks to previous experience.
- Some technicians are trying to determine the number of poles on the basis of winding pitch, but this way is quite unreliable. Here is one example: a 2 pole, single layer winding in 24 slots with pitch 1-8.
- Also, the so-called "polarity test" is not always reliable.
- What should be done? First, you should draw what you found and compare with previous diagrams. But, sometimes it is not helpful . For example: what is the number of poles for this simple three phase winding?
[img
It's not so obvious that this winding is 10 pole.
In such a case, an analysis is only help. But note that analysis is time consuming task and may be performed manually ( hard task) or by means of a suitable software. Briefly on this is here:
(please find a title: Very basic question: In what way the number of poles should be determined?)
Link
BTW, Pete, thanks for your suggestion.
http://winding.wix.com/design
RE: How to tell how many poles a motor has.
Use a low voltage dc supply (enough to deflect the needle) across one phase.
Move the compass around the inside of the stator.
It will alternate north/south as you go round.
Do this for each phase.
n/s=2 pole n/s/n/s=4 pole and so on.
RE: How to tell how many poles a motor has.