Motor Protection – Basics and Types

Induction motors are widely used in industries to meet various requirement. This can be realized by that fact that, around 90% motors used in industries are  Induction motors. The motors plays an important role in the plant process and failure or outage of motor may lead to loss in production or may even hamper the … Read more Motor Protection – Basics and Types

Air Gap Power in Induction Motor

Induction Motor works on the principle of electromagnetic induction. The three phase input power supplied to stator terminal is converted into mechanical power at the shaft output. This conversion of energy takes place through magnetic coupling between stator produced rotating magnetic flux and rotor bars. The power transfer from stator to rotor takes place through … Read more Air Gap Power in Induction Motor

Induction Motor Equivalent Circuit

We know that, induction motor is quite similar to a transformer; therefore the induction motor equivalent circuit should also be similar to that of a transformer. The only difference between them lies with the fact that, secondary winding i.e. rotor of induction motor rotates to give mechanical output whereas transformer is a static device. Thus … Read more Induction Motor Equivalent Circuit

Methods of Speed Control of Induction Motor

Out of all the electrical machines, Induction Motor is the most used machine in industries. More than 90% of motors used in industries are squirrel cage induction motor due to its rugged and maintenance free design. Generally an Induction Motor operates at almost constant speed as the load is varied. But in some industrial applications, … Read more Methods of Speed Control of Induction Motor

Stator Voltage Control of Induction Motor

Stator Voltage Control of Induction Motor is a method for the speed control of induction motor by changing the stator terminal voltage. Stator terminal voltage in this method is changed either by adding a series resistor, series inductor or auto transformer in stator circuit. But addition of series resistance is quite inefficient due to losses … Read more Stator Voltage Control of Induction Motor

Rotor resistance Control of Induction Motor

Rotor resistance control is one among the various methods for the speed control of induction motor. In this method of speed control, the rotor circuit resistance is varied by connecting a variable external resistance. This method is only applicable for slip ring or wound rotor induction motor (WRIM). As in squirrel cage induction motor (SCIM), … Read more Rotor resistance Control of Induction Motor

Pole Changing Method – Speed Control of Induction Motor

Pole changing method is a speed control scheme of induction motor. In this scheme, the number of pole pairs is changed by changing the field connection. In induction motor, field winding is wound on the stator while the armature winding is wound on the rotor. Therefore in this scheme, provision for changing the stator winding … Read more Pole Changing Method – Speed Control of Induction Motor

Torque Slip Characteristics of Induction Machine

Torque Slip Characteristics is the graphical relationship between the torque and slip of an Induction Machine. This characteristic is very useful for the stability analysis of the machine. Electromagnetic torque in an Induction Machine is given as Te = [Kx(r2/s)] / [(Re + r2/s)2 + X2]  …………………(1)  Where K = Constant From the above equation, … Read more Torque Slip Characteristics of Induction Machine