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How to calculate the slip in an three phase induction motor

  1. Sep 29, 2011 #1
    I wanted to know if it is possible to calculate the rotor slip if I know the output torque and rpm shaft. I also know the equivalent cicuit of the motor: Rs, Rr, Ls, Lm and Lr.

    Thank you!
  2. jcsd
  3. Sep 29, 2011 #2


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    Re: How to calculate de slip in an three phase induction motor

    If you know the input frequency (this is the mains frequency if it's not inverter driven) and the rotor RPM then that's all you need to calculate the slip directly from it's definition (as opposed to calculating it from the machine model).

    slip = 1 - pp * RPM / (60 * f)

    Where pp is the number of pole pairs
  4. Sep 29, 2011 #3
    The point is that the motor is supplied by a inverter with variable voltage and frequency, so I wanted to know the slip to calculate the frequency and the voltage to supply to the motor to obtain the desired torque/rpm.
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