DC Generator MCQ Questions and Answers for Practice

1. In a four-pole D.C. machine

1. alternate poles are north and south
2. all the four poles are south poles
3. two north poles follow two south poles
4. all the four poles are north poles

2. In over compounded generator, full load terminal voltage is

1. less than noload terminal voltage
2. more than noload terminal voltage
3. equal to no-load terminal voltage
4. almost zero

3. Armature coil is short circuited by brushes when it lies

1. along field axis
2. in any of the above positions
3. in none of the above positions
4. along neutral axis

4. Lap winding is composed of

1. any odd number of conductors
2. that even number which is exact multiple of poles + 2
3. that even number which is exact multiple of poles
4. any even number of conductors

5. Wave winding is composed of

1. any odd number of conductors
2. that even number which is exact multiple of poles + 2
3. that even number which is exact multiple of poles
4. any even number of conductors

6. The terminal voltage of a D.C. shunt generator drops on load because of all of thefollowing reasons except

1. armature resistance drop
2. field weakening due to armature reaction and armature
3. commutation
4. armature reaction

7. The bearings used to support the rotor shafts are generally

1. bush bearings
2. magnetic bearmgs
3. needle bearings
4. ball bearings

8. In a D.C. generator the critical resistance refers to the resistance of

1. field
2. armature
3. load
4. brushes

9. Brushes of D.C. machines are made of

1. soft copper
2. hard copper
3. all of above
4. carbon

10. Laminations of core are generally made of

1. carbon
2. silicon steel
3. stainless steel
4. case iron

11. In D.C. generators, current to the external circuit from armature is given through

1. solid connection
2. slip rings
3. none of above
4. commutator

12. Which of the following could be lamina-proximately the thickness of laminations of a D.C. machine ?

1. 0.05 mm
2. 0.5 m
3. 5 m
4. 0.005 mm

13. Which of the following statement about D.C. generators is false ?

1. In a D. C. generator interpoles winding is connected in series with the armaturewinding
2. Back pitch and front pitch are both odd and approximately equal to the pole pitch
3. Equilizing bus bars are used with parallel running of D.C. shunt generators
4. Compensating winding in a D.C. machine helps in commutation

14. In a commutator

1. mica and copper are equally hard
2. mica is harder than copper
3. none of the above
4. copper is harder than mica

15. The commutator segments are connected to the armature conductors by means of

1. resistance wires
2. insulation pads
3. brazing
4. copper lugs