For a dc machine, its commutator has a diameter of 50 c rotating at 1000 rpm. For a brush width of 1 cm, the time commutation taken by the machine will be _________(a) 0.382 ms(b) 0.456 ms(c) 0.573 ms(d) 0.312 msI have been asked this question by my college director while I was bunking the class.This question is from DC Motor Starting topic in portion DC Motors of Electrical Machines

For a dc machine, its commutator has a diameter of 50 c rotating at 10

1.	For a dc machine, its commutator has a diameter of 50 c rotating at 1000 rpm. For a brush width of 1 cm, the time commutation taken by the machine will be _________(a) 0.382 ms(b) 0.456 ms(c) 0.573 ms(d) 0.312 msI have been asked this question by my college director while I was bunking the class.This question is from DC Motor Starting topic in portion DC Motors of Electrical Machines
Answer» Right answer is (a) 0.382 ms The best explanation: Time of commutation = brush width/peripheral velocity = 160/(PI50*1000) = 0.382 ms.

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