Electrical Machines

Torque Equation of Induction Motor

The torque T, of an induction motor, is proportional to the product of stator flux per pole ( φ ), rotor current ( I ), and the power factor of the rotor. The torque of an induction motor is due to the interaction of the…

Permanent Magnet Stepper Motor - Construction & Working

A stepper motor is an electro-mechanical device that actuates a train of step movements of a shaft in response to a train of input pulses. The step movement may be angular or linear. The step movement of the motor is acc…

Ac Series Motor - Construction & Principle of Operation

Principle of Operation of A.C. Series Motor :       An ordinary d.c.series motor will run in the same direction regardless of the polarity of the supply. The direction of the torque depends upon the relative directions in s…

Cross-field Theory of Single phase Induction Motor

It is interesting to know how a single-phase induction motor can able to rotate when an initial rotation or starting torque is given to it. This can understand with the help of cross-field theory and double-revolving fiel…

Double Revolving Field Theory

When a single-phase AC supply is given to the single-phase stator winding, a sinusoidally pulsating magnetic field varying with time is produced. As the produced magnetic very two times in a cycle, therefore, no torque wi…

Speed Control of DC Motors - shunt & series

Industrial as well as domestic loads need speed variation. Some of the loads require to change the speed in steps and some of the motors require to change the speed uniformly. For instance, in the paper industry, while ro…

Torque Equation of a DC Motor

Torque or moment or moment of force is the tendency of a force to rotate or move an object about an axis. A force is a push or pull, likewise, torque is a twist to an object. Mathematically, Torque, T = F × r. Let T g…

Back E.M.F of DC Motor and Equation

What is Back E.M.F. in DC Motor :      When the armature of a d.c. motor rotates, the windings or conductors on the armature also rotate in the magnetic field. According to " Faraday's Laws of Electro-Magnetic Indu…

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