Best answer: Why AC motors are not self starting?

We can easily conclude that the single-phase induction motors are not self-starting because the produced stator flux is alternating in nature and at the starting, the two components of this flux cancel each other, and hence there is no net torque.

Why are motors not self-starting?

This is because the speed with which the magnetic field is rotating is so high that it is unable to rotate the rotor from its initial position, due to the inertia of the rotor. So under any case, whatever may be the starting position of the rotor, the synchronous motor is not self-starting.

Are AC motor self-starting?

The induction motor always runs at speed less than its synchronous speed. The rotating magnetic field produced in the stator will create flux in the rotor, hence causing the rotor to rotate. … Single phase induction motors arenot a self-starting motor, and three phase induction motor are a self-starting motor.

Which type of motor is not self-starting?

It is not synchronously revolving (or rotating) flux, as in case of 3 phase stator winding, the fed cannot produce rotation. Hence single phase induction motor is not self-starting.

What is low starting torque?

The starting torque of the motor is given by, … At start, the rotor reactance is large because slip of the motor at start is equal to unity. The large rotor reactance at start makes the starting torque of the motor poor. The motor draws about 5 to 6 times current of its full load current and produce very less torque.

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What will happen if air gap is increased in an induction motor?

If the air gap of an induction motor is increased, the following will happen: The permeability of the magnetic circuit rotor-to-stator will decrease. The magnetizing inductance of he motor thus decreases. The magnetizing current will increase.

What is the main reason why a single phase motor is not self-starting?

We can easily conclude that the single-phase induction motors are not self-starting because the produced stator flux is alternating in nature and at the starting, the two components of this flux cancel each other, and hence there is no net torque.

Which motor has highest no load speed?

Explanation: At no load, armature current tends to zero, flux φ tends to zero, where speed is inversely proportional to the flux, speed will tend to infinity. Thus, no load speed of DC series motor is highest.

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