# Stator Voltage Control of three phase induction motor

Stator Voltage Control of three phase induction motor

Stator Voltage Control of three phase induction motor

By stator voltage control :

•We have, •Torque is directly proportional to stator voltage square.

•The torque is directly proportional to speed so if torque will decrease speed also decrease and if torque will increase speed also increase.

•So we can control speed of three phase induction motor by varying stator voltage.

•This method is suitable for application where load torque decreases with speed.

•This method is sometimes used for small motor fans.

•This method is very easy and cheap but still use rarely.

•Because by decreasing the voltage torque will reduce.

•But to maintain power (P=VI) this will increase current in motor which will heat the motor which is not good it causes losses.

•Also the torque is proportional to square of voltage so large voltage change is required for changing torque.

## Related Questions

Description : In a single-phase induction motor when the rotor is stationary and voltage is applied to the stator, then (A) the flux is constant (B) the flux first decreases and then increases in ... increases and decreases in the opposite direction with the same magnitude (D) current flows through the rotor

Answer : In a single-phase induction motor when the rotor is stationary and voltage is applied to the stator, then the flux first decreases and then increases in the same direction

Description : The speed of a three-phase induction motor is controlled by variable voltage variable frequency control (i.e. keeping V/f constant). As the frequency is reduced, the slip at maximum torque  (1) Decreases (2) Increases (3) Remains constant (4) None of the above

Answer : The speed of a three-phase induction motor is controlled by variable voltage variable frequency control (i.e. keeping V/f constant). As the frequency is reduced, the slip at maximum torque Increases

Description : Explain speed control method of 3 phase induction motor by the following methods: (1) Pole changing (2) Rotor resistance control (3) Stator voltage

Answer : 1) Pole Changing Method:  Synchronous speed is given by, From the above equation of synchronous speed, it can be seen that synchronous speed (and hence, running speed) can ... in voltage and consequently the speed decreases and vice versa. Ultimately speed depends on the supply voltage.

Description : speed control methods of three phase induction motor?

Answer : Speed control of three phase induction motor

Description : Torque developed by a three-phase, 400V, induction motor is 100 N -m. If the applied voltage is reduced to 200-V, the d'veloped torque will be

Answer : Torque developed by a three-phase, 400V, induction motor is 100 N -m. If the applied voltage is reduced to 200-V, the d'veloped torque will be 25 N -m