Question

A three Phase 4 Pole induction motor is running with 1% slip .The supply frequency is 50 Hz find out the speed of induction motor.​

Answer 1

Answer:

OMG SO HARD !

LET'S MAKE IT EASY

I am not going to only making this question simple and easy for you but also try to have you some important term's about induction motor.

Let's start,

First of all an induction motor is a self starting motor in which rotation of rotor occurs due to Faraday's law of electromagnetic induction.  

There are three things rotating in it  

Stators rotating magnetic field ( this will rotates at synchronous speed Ns ).

Rotors magnetic field (this will rotates at synchronous speed w.r.t stator but at slip speed (Ns — Nr ) w.r.t rotor.

And, rotor itself (Nr this will you called as speed of motor or rotor speed).

Now to calculate synchronous speed there is a formula I would like to drive it here but now no need here :-

Ns = 120f/p

Here , Ns = synchronous speed , f = supply frequency, p= no. Of poles

Given:- f= 50Hz , p= 4

By applying above formula

Ns = 120*50/4

= 1500 rpm .

SLIP(S) — slip is nothing but the difference between synchronous speed (Ns) and the rotor speed (Nr) expressed as a percentage of synchronous speed.

S = Ns — Nr / Ns * 100

So, according to question

Nr = 1460 rpm , Ns which we already found above = 1500 rpm

S = 1500 — 1460/1500

= 2.66 %

And the last and easy part

Slip frequency or rotor induced EMF frequency

= S*f

f= 50, S =2.66%

= 50*2.66/100. ( # % ~ 1/100)

= 1.33 Hz .

Thank you! I hope this will helpful for you guys

Be happy stay fit save water