1. A D.C generator can be considered
(A) rectifier
(B) Prime Mover
(C) rotating amplifier
(D) power pump
Answer- (C)
2. In any rotating machine that holds the part conductors and in which the E.M.F. Is said to be used to induce
(A) rotor
(B) Stator
(C) Field
(D) armature
Answer- (D)
3. a D.C. What is the sum of stray loss in the machine
What is the sum of stray loss in the a D.C. machine
(A) Total copper loss and mechanical loss
(B) Armature copper loss and iron loss
(C) Shunt field copper loss and mechanical loss
(D) Iron loss and mechanical loss
Answer- (D)
4. In case of lap winding, the resultant pitch is
(A) Multiplication of front and back pitches
(B) Division of front pitch by back pitch
(C) The sum of pitches forward and backward
(D) Difference between front and back pitches
Answer- (D)
5. Which of the following components of a D.C. generator plays an important role to provide DC?
(A) Dummy coil
(B) Commutator
(C) eye bolt
(D) Equalizer ring
Answer- (B)
6. EMF induced in the armature of the shunt generator. 600v. The armature resistance is 0.1 ohms. If the armature current is 200 A, the terminal voltage will be
26. induced EMF in the armature of the shunt generator 600v. The armature resistance is 0.1 ohms. If the armature current is 200 A, the terminal voltage will be
(A) 640 V
(B) 620 V
(C) 600 V
(D) 580 V
Answer- (D)
7. Refers to the resistance of the critical resistance in the A D.C. generator
(A) Brush
(B) Field
(C) armature
(D) load
Answer- (B)
8. In DC generators, lap windings are used
(A) High voltage, high current
(B) low voltage, high current
(C) high voltage, low current
(D) low voltage, low current
Answer- (B)
9. Two generators A and B each have 6 poles. Generator A has wave wound armature winding while generator B has lap wound armature winding. Inspired EMF The ratio of generators A and B will be
(A) 2: 3
(B) 3: 1
(C) 3: 2
(D) 1: 3
Answer- (B)
10. For which of the following types of brushes can the voltage drop be expected to be minimal?
(A) Graphite Brush
(B) Carbon Brush
(C) Metal graphite brush
(D) None of the above
Answer- (C)
11. emf is generated by a dc shunt wound generator. Now that the pole flux remains constant, if the generator speed is doubled, how much e.m.f. Will arise
(A) E / 2
(B) 2 E
(C) slightly less than E
(D) E
Answer- (B)
12. The material for the commutator brush is usually
(A) Asbestos
(B) copper
(C) Cast iron
(D) Carbon
Answer- (D)
13. in D.C. generator EMF ripples can be reduced by
(A) using annealed copper conductors
(B) Using a commutator with a large number of segments
(C) Using better quality carbon brushes
(D) using equalizer rings
Answer- (C)
14. Insulating materials used between commutator sections are normally
(A) graphite
(B) paper
(C) Asbestos
(D) insulating varnish
Answer- (C)
15. In D.C generators, the brushes on the commutator are in contact with the conductor which
(A) is located below the South Pole
(B) is located below the North Pole
(C) is located below the inter pole region
(D) Farthest from the poles
Answer- (C)
16. If a brush of a D.C generator is moved to bring these brushes to the magnetic neutral axis, then there will be
(A) Demagnetisation only
(B) cross magnetisation along with magnetisation
(C) Demagnetising along with magnetisation
(D) cross magnetisation only
Answer- (C)
17. The armature reaction of an unsaturated D.C machine is
(A) Cross Magnetizing
(B) demagnetizing
(C) magnetized
(D) None of the above
Answer- (A)
18. A DC welding generator is
(A) lap winding
(B) Wave winding
(C) duplex winding
(D) any of the above
Answer- (A)
19. D.C generators are connected to busbars or disconnected from floating condition only under temporary condition
(A) To avoid sudden loading of prime mover
(B) To avoid mechanical shock to the shaft
(C) To avoid the burning of switch contacts
(D. ALL OF THE ABOVE
Answer- (D)
20. The purpose of providing a dummy coil in a generator is
(A) to reduce eddy current losses
(B) to increase flux density
(C) increasing the voltage
(D) To provide mechanical balance for the rotor
Answer- (D)