# How to calculate the slip in an three phase induction motor

Hello!
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!

Related Electrical Engineering News on Phys.org
uart

Hello!
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!
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

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.