Join 60,000+ competitive exam aspirants
or with email
Your Cart
Subtotal₹0
Total₹0
Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
Join 60,000+ competitive exam aspirants
The rotor of a three-phase induction motor can never attain synchronous speed.
True
False
depends on the load condition
depends on the supply voltage
True
The statement that the rotor of a three-phase induction motor can never attain synchronous speed is true. This is because the rotor must always rotate slower than the synchronous speed in order to produce torque.
The statement that the rotor of a three-phase induction motor can never attain synchronous speed is true. This is because the rotor must always rotate slower than the synchronous speed in order to produce torque.
ωr<ωs — Rotor speed is always less than synchronous speed.
In a three-phase induction motor, the rotating magnetic field produced by the stator induces currents in the rotor. These currents create their own magnetic field, which interacts with the stator's magnetic field to produce torque. For this interaction to occur, the rotor must rotate at a speed less than that of the magnetic field; otherwise, no relative motion exists to induce the necessary currents, resulting in zero torque.
The rotor operates at a speed lower than the synchronous speed to generate torque.
The speed difference between the synchronous speed and rotor speed is known as slip.
Simple construction and operation
Robust and reliable under varying load conditions
Lower efficiency compared to synchronous motors
Limited speed control without additional equipment
Industrial drives
Pumps and fans
Standard value or specification: Typical slip values range from 2% to 6%.
Option B is incorrect because it suggests that the rotor can attain synchronous speed, which contradicts the principles of induction motors.
A is correct — The rotor of a three-phase induction motor must rotate slower than synchronous speed to produce the necessary torque.
Understand the principles of slip and how torque production in induction motors depends on the speed difference between the rotor and the magnetic field.