If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens__________?
Correct answer: C. this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses D. motor will run at very slow speed
- A. nothing will happen to the motor
- B. this will make armature to take heavy current, possibly burning it
- C. this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses D. motor will run at very slow speed
Explanation
If the shunt field opens, the motor flux collapses while the applied voltage remains, causing a dangerous rise in speed. The armature may be damaged by excessive centrifugal stress, so option c is correct.
Last updated
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.
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.
Related questions
5 H.P., 50-Hz, 3-phase, 440 V, induction motors are available for the following r.p.m. Which motor will be the costliest ?
A 220 V D.C. generator is run at full speed without any excitation. The open circuit voltage will be_____________?
A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor e.m.f. will be____________?
A 3-phase induction motor delta connected is carrying too heavy load and one of its fuses blows out. Then the motor______________?
A 3-phase induction motor stator delta connected, is carrying full load and one of its fuses blows out. Then the motor_______________?