What will happen in induction motor if we increase the air gap flux?

Detailed Solution. If the air gap of an induction motor increases, 1) The permeability of the magnetic circuit rotor-to-stator will decrease. 2) The magnetizing inductance of the motor thus decreases.

What is the effect of load on the efficiency of an induction motor?

1. The efficiency of the induction increases when the mechanical load increases because as the motors load increases, its slip increases, and the rotor speed falls. Since the rotor speed is slower, there is more relative motion between the rotor and the stator magnetic fields in the machine.

How can we increase the RPM of single phase motor?

You increase the speed by increasing the frequency. If a motor base speed is 60 Hz, raising the frequency to 120 Hz will double the speed of the motor. However, if you do not keep the volt to hertz ratio constant, you will cause the motor windings to heat up.

How does the number of Poles affect the speed of a motor?

The main thing to understand is that increasing the number of poles reduces the motor’s synchronous speed. A 2 pole motor on 60 hz power has a synchronous speed of 3,600 rpm. For an induction motor, that will typically drop by a “slip” percentage, typically about 4\% to 3,450 rpm.

What is the speed of an induction motor?

The induction motor will run at a slight less speed due to “slip” which is what gives the motor its torque. For example 5.5kW, 400v, 2 pole motor will run at approximately 2880 rpm. For a four pole machine, 60 x 50 / 2 = 1500 rpm so the same size motor at 5.5kW, 400v but 4 poles will have a nominal speed of 1500rpm but will run near 1455 rpm.

How do you calculate the number of poles of an induction motor?

To determine the number of poles, you can read the data plate directly or calculate it from the RPM stated on the data plate or you can count the coils and divide by 3 (poles per phase) or by 6 (pairs of poles per phase). Where the power of the induction motor is constant,…

How do you increase the torque of a 4 pole motor?

A 4 pole motor on 60 hz power has a synchronous speed of 1,800 rpm, induction less slip of 4\% = 1,725 rpm. The reason that is important is that mechanical power = torque x rpm. Reduce the rpm to half, then you must increase the torque x 2 to maintain the same horsepower (kW) mechanical output. To double the torque of a