Top 350+ Solved Electrical Machine 1 MCQ Questions Answer
Q. Which of the following loss in a D.C. generator is dissipated in the form of heat?
a. Mechanical loss
b. Core loss
c. Copper loss
d. All of the above
Q. Which of the following losses are significantly reduced by laminating the core of aD.C. generator ?
a. Hysteresis losses
b. Eddy current losses
c. Copper losses
d. Windage losses
Q. The total losses in a well designed D.C. generator of 10 kW will be nearly
a. 100 W
b. 500 W
c. 1000 W
d. 1500 W
Q. The condition for maximum efficiency for a D.C. generator is
a. eddy current losses = stray losses
b. hysteresis losses = eddy current losses
c. copper losses = 0
d. variable losses = constant losses
Q. D.C. generators are normally designed for maximum efficiency around
a. full-load
b. rated r.p.m.
c. rated voltage
d. all of the above
Q. In a D.C. generator, the iron losses mainly take place in
a. yoke
b. commutator
c. armature conductors
d. armature rotor
Q. D.C. generators are installed near the load centres to reduce
a. iron losses
b. line losses
c. sparking
d. corona losses
Q. The purpose of retardation test on D.C. shunt machines is to find out
a. stray losses
b. eddy current losses
c. field copper losses
d. windage losses
Q. Which of the following tests will be suitable for testing two similar D.C. series motors oflarge capacity ?
a. Swinburne'stest
b. Hopkinson'stest
c. Field test
d. Brake test
Q. Hopkinson's test on D.C. machines is conducted at
a. no-load
b. part load
c. full-load
d. overload
Q. During rheostat braking of D.C. series motors
a. motor is run as a generator
b. motor is reversed in direction
c. motor is run at reduced speed
d. all
Q. For which types of D.C. motor, dynamic braking is generally used ?
a. Shunt motors
b. Series motors
c. Compound motors
d. All of the above
Q. Which method of braking is generally used in elevators ?
a. Plugging
b. Regenerative braking
c. Rheostatic braking
d. None of the above
Q. In variable speed motor
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
Q. When the armature of a D.C. motor rotates, e.m.f. induced is
a. self-induced e.m.f.
b. mutually induced e.m.f.
c. back e.m.f.
d. none of the above