Answer / cnu

For the speed control of an induction motor if you consider
to change the number of poles, every time you want to
change a speed you cant remove or add the poles to a motor
coz this is done while manufacturing the machine.

So for the speed control of an induction motor we use the
Variable-Frequency Drive (VFD) which takes in the standard
voltage at 50Hz frequency and gives the output at any
frequency required. the frequency can vary from 0 Hz to
50Hz and we can also increase the frequency more than 50Hz
to make the motor run with speeds higher than the rated
speed of the motor.

Answer / mrinmoy

yes

Answer / burning fuel

yes we can control speed both by varying the no. of poles &
frquency.

Answer / ranjan

yes, definitely.as u know we are using the VFD drives for
speed variation w.r.t frequency.

Answer / seenivasan

Frequency is not a constant one.it will vary in between
47-49hz during transmisson.if it goes less r more than these
range transformer ll trip.as we know VFD(variable Frequency
Drives).So by using frequency we ll control the electrical
equipments.

Answer / naveen

Yes we can able to change the frequency of the supply by using of the cyclo converter and PWM inverter these power electronics circuits used to change the frequency and we achieve the variable freq and vary the speed of the IM

Answer / kanagaraj

frequency don't change........... because frequency also
fixed for goverment..............

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