Which method of braking is generally used in elevators ?
Which method of braking is generally used in elevators ? A. Plugging B. Regenerative braking C. Rheostatic braking D. None of the above
Which method of braking is generally used in elevators ? A. Plugging B. Regenerative braking C. Rheostatic braking D. None of the above
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
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
Hopkinson’s test on D.C. machines is conducted at_______________? A. no-load B. part load C. full-load D. overload
Which of the following tests will be suitable for testing two similar D.C. series motors of large capacity ? A. Swinburne’s test B. Hopkinson’s test C. Field test D. Brake test
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
D.C. generators are installed near the load centres to reduce_____________? A. iron losses B. line losses C. sparking D. corona losses
In a D.C. generator, the iron losses mainly take place in___________/ A. yoke B. commutator C. armature conductors D. armature rotor
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
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