The 'crawling" in an induction motor is caused by___________?
Correct answer: D. harmonics developed in the motor
- A. high loads
- B. low voltage supply
- C. improper design of machine
- D. harmonics developed in the motor
Explanation
Crawling is produced by harmonic components of the air-gap flux, especially the seventh harmonic, which can create a low-speed torque near one-seventh of synchronous speed. It is therefore a harmonic effect rather than simply a high-load or low-voltage condition.
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