Why do we need to reduce the voltage of large induction motors during starting?

Why do we need to reduce the voltage of large induction motors during starting?

Reduced Voltage Starters enable the AC induction motor to speed up in smaller, resulting in less current drawn than with a traditional motor starter. Due to decreased voltage, torque is also reduced resulting in a soft, or easy start. Reduced Voltage Starters are used on all types of AC and DC motors.

What causes the current to decrease as an induction motor accelerates?

The rotating rotors magnetic field generates a reverse voltage in the main field windings which opposes the applied voltage. The faster the rotor turns the higher the reverse voltage generated is. This opposes the applied voltage and reduces the current flow.

Will a motor run at lower voltage?

Operating a motor at a voltage below nominal generally has no detrimental effect on performance. In fact, running a motor at lower than nominal voltage (and, therefore, slower than nominal speed) can result in less brush and commutator wear (for brushed motors), lower current consumption, and longer motor life.

Why do we reduce voltage?

Slower ‘speed’ means less work is being done. which means less power is needed. The lower voltage means less power in -which is what is need as the motor is doing less work. If we kept the input power the same, losses would have to increase as reducing the ‘speed’ means less useful work is done.

What happens if an induction motor runs below its rated voltage?

If the induction motor runs below its rated voltage, the flux will reduce and as a result, the torque delivering capacity of the motor will get reduced. If the motor drives the same load at reduced voltage, it will draw more current and will get overload tripped.

What is stator voltage control of induction motor?

Stator Voltage Control of an Induction Motor. Stator Voltage Control is a method used to control the speed of an Induction Motor. The speed of a three phase induction motor can be varied by varying the supply voltage.

How can the speed of a three phase induction motor be varied?

The speed of a three phase induction motor can be varied by varying the supply voltage. As we already know that the torque developed is proportional to the square of the supply voltage and the slip at the maximum torque is independent of the supply voltage.

Why does a single phase motor run with reduced torque?

If it is a single phase motor, it should come up to speed with no load, but under load may not get up to speed. Since the Torque is directly proportional to the square of the applied voltage incase of Induction motor.So obviously the motor will run with reduced torque. Dwayne is in hot water for his latest comments.