Induction motor starting direction

AI Thread Summary
Induction motors start in a consistent direction due to the phase difference between the start and run windings, which creates a directional torque. The start winding induces a magnetic field that positions the north pole at 12:00 o'clock, while the run winding peaks later, creating a south pole at 3:00 o'clock and a north pole at 9:00. This configuration ensures that the motor rotates clockwise each time it starts. The interaction between the windings establishes a directional bias essential for consistent operation. Understanding this mechanism clarifies why induction motors have a predictable starting direction.
John94N
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I have a question on induction motor starting direction. I understand the phase delay between the running winding and starting winding, but I don’t see why an induction motor should start in the same direction each time. Is there a directional bias on the stator or rotor coils that ensures the torque is always in one direction?
 
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The bias is obtained from the start winding used in conjunction with the run winding to start the motor.

Let's say the start winding induces a magnetic field in the armature so the north pole is at 12:00 o'clock. After a delay, the run winding peaks with it's south pole at 3:00 o'clock and north pole at 9:00. This will induce the armature to rotate clockwise.
 
That's makes sense. Thanks.
 
You're welcome. Glad to help.
 

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