In variable speed motor___________?
Correct answer: B. a weaker commutating field is needed at low speed than at high speed
- A. a stronger commutating field is needed at low speed than at high speed
- B. a weaker commutating field is needed at low speed than at high speed
- C. same commutating field is needed at low speed than at high speed
- D. none of the above is correct
Explanation
At higher speed, commutation occurs in less time, so a stronger interpole or commutating field is needed to reverse armature current properly. Therefore the required commutating field is weaker at low speed than at high speed.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? [email protected]
Practise Electrical Machines
1,061 free Electrical Machines MCQs from Electrical Engineering, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Electrical Engineering questions like this
Electrical Engineering is on 2 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Electrical Machines questions
When the armature of a D.C. motor rotates, e.m.f. induced is___________?
Where D.C. motor of H.P. 12 or more requires frequent starting, stopping, reversing and speed control______________?
D.C. motor is to drive a load which has certain minimum value for most of the time and some peak value for short duration. We will select the________________?
Which method of braking is generally used in elevators ?
For which types of D.C. motor, dynamic braking is generally used ?
During rheostat braking of D.C. series motors_____________?