D.C. Generators Multiple Choice Questions And Answers In English -05

1. Wave winding is composed of
(A) any even number of conductors
(B) any odd number of conductors
(C) that even number which is exact multiple of poles + 2
(D) that even number which is exact multiple of poles
Ans: C

2. D.C. series generator is used
(A) to supply traction load
(B) to supply industrial load at constant voltage
(C) voltage at the toad end of the feeder
(D) for none of the above purpose
Ans: C

3. The critical resistance of the D.C. generator is the resistance of
(A) field
(B) brushes
(C) armature
(D) load
Ans: A

4. When two D.C. series generators are running in parallel, an equalizer bar is used
(A) to increase the speed and hence generated e.m.f.
(B) to increase the series flux
(C) so that two similar machines will pass approximately equal currents to the load
(D) to reduce the combined effect of ar-mature reaction of both machines
Ans: C

5. Following D.C. generator will be in a position to build up without any residual magnetism in the poles
(A) series generator
(B) shunt generator
(C) compound generator
(D) self-excited generator
Ans: D

6. Which of the following generating machine will offer constant voltage on all loads ?
(A) Self-excited generator
(B) Separately excited generator
(C) Level compounded generator .
(D) All of the above
Ans: C

7. Which of the following generators will be preferred if they are required to be run in parallel ?
(A) Shunt generators
(B) Series generators
(C) Compound generators
(D) None of the above
Ans: A

8. Interpole flux should be sufficient to
(A) neutralise the commutating self induced e.m.f.
(B) neutralise the armature reaction flux
(C) neutralise both the armature reaction flux as well as commutating e.m.f. induced in the coil
(D) perform none of the above functions
Ans: C

9. Two generators are running in parallel. One of the generators may run as motor for which of the following reasons ?
(A) The direction of that generator is reversed
(B) The speed of that generator is increased
(C) The field of that generator is weakened
(D) That generator takes large share of loads
Ans: D

10. Flashing the field of D.C. generator means
(A) neutralising residual magnetism
(B) creating residual magnetism by a D.C. source
(C) making the magnetic losses of forces parallel
(D) increasing flux density by adding extra turns of windings on poles
Ans: B

11. A D.C. generator works on the principle of
(A) Lenz’s law
(B) Ohm’s law
(C) Faraday’s law of electromagnetic induction
(D) none of the above
Ans: C

12. A series generator can self-excite
(A) only if the load current is zero
(B) only if the load current is not zero
(C) irrespective of the value of load current
(D) none of the above
Ans: B

13. D.C. generator generally preferred for charging automobile batteries is
(A) series generator
(B) shunt generator
(C) long shunt compound generator
(D) any of’the above
Ans: C

14. A shunt generator can self-excite
(A) only if the resistance of the field circuit is less than critical value
(B) only if the resistance of the field circuit is greater than critical value
(C) irrespective of the value of the resistance in the field circuit
Ans: A

15. The terminal voltage of a series generator is 150 V when the load current is 5 A. If the load current is increased to 10 A, the terminal voltage will be
(A) 150 V
(B) less than 150 V
(C) greater than 150 V
(D) none of the above
Ans: C

16. A shunt generator running at 1000 r.p.m. has generated e.m.f. as 200 V. If the speed increases to 1200 r.p.m., the generated e.m.f. will be nearly
(A) 150 V
(B) 175 V
(C) 240 V
(D) 290 V
Ans: C

17. The open circuit voltage of a compound generator is 250 V. At full load the terminal voltage
(A) will be less than 250 V
(B) will always be 250 V
(C) may be greater or less than 250 V
(D) none of the above
Ans: C

18. Two D.C. shunt generators, each with armature resistance of 0.02 ohm and field resistance of 50 ohm run in parallel and supply a total current of 1000 amperes to the load circuit. If their e.m.fs. are 270 V and 265 V, their bus bar voltage will be
(A) 270 V
(B) 267.5 V
(C) 265 V
(D) 257.4 V
Ans: B

19. The essential condition for parallel operation of two D.C. generators is that they have ‘
(A) same kW rating
(B) the same operation r.p.m.
(C) the same drooping voltage characteristics
(D) same percentage regulation
Ans: C

20. In D.C. generators on no-load, the air gap flux distribution in space is
(A) sinusoidal
(B) triangular
(C) pulsating
(D) flat topped
Ans: D