What is flux in induction motor?

The rotating magnetic flux induces currents in the windings of the rotor, in a manner similar to currents induced in a transformer’s secondary winding(s). The induced currents in the rotor windings in turn create magnetic fields in the rotor that react against the stator field.

Are induction motors constant torque?

Typically, the induction motor is designed to provide a continuous torque rating of about 40\%–50\% of its maximum torque. (b) Constant power: For higher speed, the frequency of the inverter can be increased, but the supply voltage has to be kept constant at the maximum value available in the supply.

Is induction motor constant speed?

The induction motor is almost a constant speed motor. The speed the rotor flux slightly lags the stator flux and there exist a relative speed between stator and the rotor.

What is the effect of an increase in the flux on the induction motor?

Higher flux increases the motor torque capability. When motor operates at higher V/Hz than rated, the overfluxing occurs, which may cause saturation of the stator and rotor magnetic core. Saturation causes overheating and can lead to motor failure.

Which motor has stator flux and rotor flux?

The rotor and stator flux speed are stationary with respect to each other in 3 phase induction motor.

Why induction is called generalized transformer?

Induction motor is a generalized transformer. There is no air gap between primary and secondary of transformer where as there is a distinct air gap between stator and rotor of motor which gives mechanical movability to motor.

What is constant in induction motor?

An AC induction motor is supposed to be a constant power motor, which implies it draws more current on low voltage. Consider a motor running a constant torque load at a particular speed. The starting should be greater the system torque at time of starting. …

What is the torque of induction motor?

Torque is the turning force through a radius – with the units Nm in the SI-system and the units lb ft in the imperial system. The torque developed by an asynchronous induction motor varies when the motor accelerates from zero to maximum operating speed.

Which motor works on constant speed?

Working principle of synchronous motor: Synchronous motors are doubly exciting machines, i.e., two electrical inputs are provided to it. We provide a three-phase supply to the three-phase stator winding, and DC to the rotor winding.

In which type of motor flux is constant?

shunt wound DC motor
Thus the field flux remains more or less constant, and for this reason, a shunt wound DC motor is called a constant flux motor. You can learn more about DC motors by studying our collection of over 1000 electrical questions.

Why is VF ratio kept constant?

Higher flux than its rated capacity leads to increased eddy current and hysteresis losses. The increased losses cause the heating of the core and as a result of this the insulation of core will get damaged. Therefore, when motor running through VFD the V/f ratio is kept constant.

Why do induction motors need air gaps?

The air gap needs to be large enough to prevent contact between the rotor and stator, taking into account tolerances related to their respective dimensions, loose bearings, and movement that results from deflection during operation.

Why are induction motors always controlled by a constant ratio of voltage?

It seems that induction motors are always controlled using a constant ratio of voltage over frequency. Why is that? Take the classic torque-speed characteristic curve – varying the frequency shifts it sideways such that it’s possible to start the machine, and control it at any operating point within the frequency and rated torque limits.

What is the relationship between voltage and flux in a motor?

With constant supply power frequency, higher voltage causes higher V /Hz ratio and higher flux. With constant supply voltage, lower supply frequency would cause higher V /Hz ratio and higher flux. Higher flux increases the motor torque capability.

How does stator flux affect the performance of induction motor?

The variation in one parameter alone will lead to an increase/decrease of stator flux that deteriorates the performance of an induction motor in terms of delivery of rated torque as the torque of the motor is directly proportional to the flux.

What is the power range of an induction motor?

For a standard induction motor, this value is normally 0.2 p.u., producing a constant power range up to two to three times the rated speed. By contrast, induction motors for high-speed drives often have a constant power region range over four times the rated speed.