Poles in an Induction Motor

CE Designer

CE Designer

@ce-designer-BWq0yl • Oct 25, 2024
What are the functions of the poles in an induction motor and how does increasing/decreasing their number change the operational characteristics of the motor?
Like 0 Replies 5

Replies

Welcome, guest

Join CrazyEngineers to reply, ask questions, and participate in conversations.

Sign up Log in

CrazyEngineers powered by Jatra Community Platform

  • Vishal Sharma

    Vishal Sharma

    @vishal-pysGmK • Oct 30, 2012

    Poles are nothing but the metallic conductors around which the copper winding is done so that it acts like an electromagnet when current passes through them. The rotation of the motor is due to the magnetic field produced by these electromagnets..
    Hence, more number of poles = more speed

    <a href="https://www.youtube.com/watch?v=HWrNzUCjbkk" target="_blank" rel="nofollow noopener noreferrer">- YouTube</a>



    This video will definitely help you understanding it! 😀
  • CE Designer

    CE Designer

    @ce-designer-BWq0yl • Oct 31, 2012

    The reason I asked is because I was searching for a 3 hp low rpm motor and a supplier told me that the lower speed motors carry more poles than the higher speeds and are therefore more expensive. Now I am more confused 😕
    Which is it and why?
  • lal

    lal

    @lal-R60Xjx • Oct 31, 2012

    Well, actually more number of poles means lower speed. But better torque.

    The synchronous speed is given by, Ns = 120*f/p
    Where f is the supply frequency and p is the number of poles. Speed is inversely proportional to the number of poles.

    In the case of an Induction motor there is another factor called slip. The induction motor can never run at synchronous speed which is given by the above equation. If it was to run at that speed, then the rotor wouldn't cut any flux. So always an induction motor runs at a lower speed than the synchronous speed. This variation in the speed is slip.

    The speed at which an induction motor runs is given by Na = (synchronous speed) x (slip)
  • CE Designer

    CE Designer

    @ce-designer-BWq0yl • Oct 31, 2012

    lal
    Well, actually more number of poles means lower speed. But better torque.

    The synchronous speed is given by, Ns = 120*f/p
    Where f is the supply frequency and p is the number of poles. Speed is inversely proportional to the number of poles.

    In the case of an Induction motor there is another factor called slip. The induction motor can never run at synchronous speed which is given by the above equation. If it was to run at that speed, then the rotor wouldn't cut any flux. So always an induction motor runs at a lower speed than the synchronous speed. This variation in the speed is slip.

    The speed at which an induction motor runs is given by Na = (synchronous speed) x (slip)
    Thanks that clears things up a bit
  • Vishal Sharma

    Vishal Sharma

    @vishal-pysGmK • Oct 31, 2012

    I think everything is clear with that! 😀