Question

An induction motor when started on load does not accelerate up to full speed but runs at \({\frac {1}{17}}\)th of the rated speed. The motor is said to be:

• A. Locking
• B. Plugging
• C. Crawling
• D. Cogging

Hint:

A motor is in a crawling condition when it runs at very low speeds, typically much lower than its rated speed, due to excessive load or low voltage.

Answer 1

The Correct Option is C

When an induction motor operates at a very low speed, such as 1/17 of the rated speed, it is said to be in the crawling condition. This condition often occurs when the motor is started with a load that prevents it from reaching full speed.
- Locking occurs when the motor does not rotate at all.
- Plugging is when the motor is run in reverse to bring it to a stop.
- Cogging happens when the motor starts and stops periodically due to insufficient torque at very low speeds.
Thus, the correct answer is that the motor is in a crawling condition.