pulling the motor directly on line without a starter
locking of rotor due to harmonics
starting the motor on load which is more than the rated load
interchanging two supply phases for quick stopping
Answer is Wrong!
Answer is Right!
The correct answer is D. interchanging two supply phases for quick stopping.
Plugging is a method of stopping a three-phase induction motor quickly. It is done by interchanging two of the supply phases. This causes the motor to rotate in the opposite direction, which quickly brings it to a stop.
Option A is incorrect because pulling the motor directly on line without a starter can damage the motor.
Option B is incorrect because locking of rotor due to harmonics is a condition that can cause the motor to overheat and stop.
Option C is incorrect because starting the motor on load which is more than the rated load can also damage the motor.