How to Find RPM of AC Motor From Poles

AC motor name plate have data from which we can get the information about motor. Generally an AC Motor name plate have the motor KW/HP rating, Current , Voltage and current rating.Design,efficiency and operating frequency are also indicated on the motor nameplate. Also we can find the number of poles written at motor name plate. Today we will see that what does poles means in reference to AC Motor.

What is Pole in AC Motor :-
Well pole indicates the number of magnetic poles that appear inside the motor when ac power is supplied to its power terminals. We should understand the poles always exist in set inside a motor i.e poles always are in even numbers.

How to Calculate RPM of Motor from Poles and Frequency :-
The synchronous speed of a motor is always calculated from the number of poles in conjugation with the frequency.
To calculate the RPM of a motor you just need to apply the below formula.
RPM = 120F/P
Where :-
F = Frequency
P = Number of poles

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Below is the picture in which RPM of motor having 2,4,6,8 poles at different operating frequency of 50/60 Hz is shown

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