781. Which of the following steps is likely to result in reduction of hysteresis loss in a D.C. generator ?
A. Providing laminations in armature core
B. Providing laminations in stator
C. Using non-magnetic material for frame
D. Using material of low hysteresis co-efficient for armature core material
782. 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
783. Which of the following losses are significantly reduced by laminating the core of a D.C. generator ?
A. Hysteresis losses
B. Eddy current losses
C. Copper losses
D. Windage losses
784. 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
785. 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
786. 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
787. In a D.C. generator, the iron losses mainly take place in___________/
A. yoke
B. commutator
C. armature conductors
D. armature rotor
788. D.C. generators are installed near the load centres to reduce_____________?
A. iron losses
B. line losses
C. sparking
D. corona losses
789. 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
790. 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
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