I need to understand the design of a single phase induction motor (I think it is a permanent split capacitor motor).

The motor works on three different speeds. It has 8 poles as shown in figure.

Let's assume that coils 5 & 7 are the main (Running) coils. So, Coils 6 & 8 are the starting (auxiliary) coils that are connected to a capacitor.

There are 4 more coils:

1.What are they used for?

2.Which one is north? and Which one is south?

3.Which one is a main coil and Which one is auxiliary?

4.Can I differentiate between main coils and auxiliary coils visually?

enter image description here

More information about my Motor:

1It is a motor of a small table fan (220V - 40 watts). A picture of a fan that is similar to mine is here: http://konwin.gmc.globalmarket.com/products/details/small-standing-fan-1547568.html

The motor has 16 solts.

  • \$\begingroup\$ That is much more likely a shaded pole motor, which is typical on fans. The auxiliary coils 'shade' the main coils to generate enough of a phase difference to get the motor to start turning. \$\endgroup\$
    – R Drast
    Commented Dec 15, 2015 at 13:39
  • \$\begingroup\$ My motor is identical to the motor in this video: youtu.be/toaWJoV-BGk?t=4m10s \$\endgroup\$ Commented Dec 15, 2015 at 13:45

1 Answer 1


Based on the video, I believe that you are correct. This is a permanent split capacitor motor. The capacitor is connected in series with the auxiliary winding to provide a phase shift to the current in that winding so that the motor has a defined direction of rotation and will start automatically. The best way to identify the auxiliary winding is to observe its series connection with the capacitor. It may also have slightly smaller wire. There are four main coils and for auxiliary coils in a 4-pole motor.

  • \$\begingroup\$ Thank you for your answer. I need to re-wind this motor and rewinding is a very boring process and takes a lot of time :) so I want to be sure of what I'm doing. I provided a picture and I put numbers on each coil from 1 to 8. Would you tell me which poles should be north, Please? and Which one should be auxiliary coil? \$\endgroup\$ Commented Dec 15, 2015 at 16:47
  • 1
    \$\begingroup\$ You will probably need to observe very carefully how the coils are wound and connected when you take the motor apart. The switch is probably connected to three places in the windings. You will need to count the number of turns to the switch connections. There are different ways this might be done. \$\endgroup\$
    – user80875
    Commented Dec 15, 2015 at 18:04

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