Question

I'm doing an induction motor assignment and trying to find out the difference between Ns and N in the equation......N=(Ns)*(1-S), please describe the difference, and what word should I look for when trying to identify Ns or N in a problem's description.

Answer 1

In an induction motor the rotating magnetic field or flux rotates with Ns.( Snchronous speed)

And rotor of motor revolves with speed N. SPEED OF ROTOR IS ALWAYS LESS THAN FLUX.

So slip tells us the difference between rotating magnetic field speed and rotor speed of a synchronous motor

It is always expressed as a function of syncronous speed or we can say that slip speed is the relative speed

Between rotaing magnetic field and rotor of the induction motor

1. Slip(s)=(Ns-N)/Ns. Where Ns =(120*frequency)/no. Of poles.

Ns=synchronous speed , N=rotor speed.

2.rotor of induction motor always lags behing rotating magnetic field.

S=is called as slip of the induction motor