Crawling & Cogging in Induction Motor - MCQs with Answers

Crawling & Cogging in Induction Motor - MCQs with Answers


Q1. Crawling in an induction motor is caused

a. During starting of an induction motor
b. At the fraction of rated speed
c. Due to insulation failure
d. All of these

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ANSWER: b. At the fraction of rated speed



Q2. Cogging in an induction motor is caused

a. If the number of stator slots are integral multiple of rotor slots
b. If the motor is running at fraction of its rated speed
c. Due to fifth harmonic
d. All of these

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ANSWER: a. If the number of stator slots are integral multiple of rotor slots



Q3. Crawling is a phenomena mainly associated with

a. 3rd harmonic
b. 5th harmonic
c. 7th harmonic
d. 2nd harmonic

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ANSWER: c. 7th harmonic



Q4. What happens if the number of stator slots in an induction motor is equal to the number of rotor slots or integral multiple of rotor slots?

a. Motor will run at very high speed
b. Motor will run at very low speed
c. Motor will fail to start
d. Does not get effected

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ANSWER: c. Motor will fail to start



Q5. The crawling and cogging is not predominant in

a. Slip ring induction motor
b. Squirrel cage induction motor
c. Both (a) and (b)
d. None of these

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ANSWER: a. Slip ring induction motor


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