16) The commutator pitch for a simplex lap winding is equal to

  1. number of poles of the machine
  2. poles pair
  3. 1
  4. none of the above
ANSWER
Answer: ( 1 )
EXPLANATION
The commutator pitch foe a simple lap winding is given by:

Yc = 1.

17) The number of parallel path in a simplex wave winding is

  1. number of poles in the machine
  2. 2
  3. number of pair of poles
  4. none of the above
ANSWER
Answer: ( 2 )
EXPLANATION
No answer description required for this question.

18) The relation among commutator pitch Yc, front pitch Yf and back pitch Yb is ……….

  1. Yc = algebraic sum of Yb and Yf
  2. Yc = algebraic difference of Yb and Yf
  3. Yc = Yb/Yf
  4. none of the above
ANSWER
Answer: ( 2 )
EXPLANATION
No answer description required for this question.

19) In a DC machine, the number of commutator segments is equal to

  1. number of conductors
  2. twice the number of poles
  3. number of coils
  4. none of the above
ANSWER
Answer: ( 3 )
EXPLANATION
In a DC armature winding, the two ends of the coils are connected to two different commutator segments and two coils are connected to each segment so that number of commutator segments is equal to the number of coils.

20) The DC machine armature winding nature is decided by ……….

  1. front pitch
  2. commutator pitch
  3. back pitch
  4. none of the above
ANSWER
Answer: ( 2 )
EXPLANATION
It is the commutator pitch that determines the grouping of the coils in series and parallel. In other words, it is the commutator pitch that determines as to how many parallel paths, each consisting of equal number of coils in series, will be formed. Hence, the nature of the winding is determined by the commutator pitch.

21) DC machines with high voltages uses ……….. winding

  1. lap
  2. wave
  3. either wave or lap
  4. none of the above
ANSWER
Answer: ( 2 )
EXPLANATION
No answer description required for this question.

22) The number of brushes required in lap winding machine is equal to ………

  1. number of poles
  2. number of pair of poles
  3. commutator pitch
  4. none of the abve
ANSWER
Answer: ( 1 )
EXPLANATION
No answer description required for this question.

23) In a wave winding, the commutator pitch is equal to ……….

  1. pole pitch
  2. twice the pole pitch
  3. thrice the pole pitch
  4. none of the above
ANSWER
Answer: ( 2 )
EXPLANATION
No answer description required for this question.

24) For a given number of poles and armature conductor, a lap winding will carry ………… a wave winding

  1. more current than
  2. less current than
  3. same current as
  4. none of the above
ANSWER
Answer: ( 1 )
EXPLANATION
No answer description required for this question.

25) An 8 pole duplex lap winding will have ……………. parallel paths.

  1. 4
  2. 8
  3. 16
  4. 32
ANSWER
Answer: ( 3 )
EXPLANATION
With a n-plex lap winding, the number of parallel paths is P n where

P = number of poles

n =  2, 3 etc and stands for duplex or triplex etc….

26) In a DC generator, the generated voltage depends upon ………….

  1. flux only
  2. speed only
  3. both speed and flux
  4. none of the above
ANSWER
Answer: ( 3 )
EXPLANATION
No answer description required for this question.

27) A 6 pole lap wound generator has 300 conductors, the e.m.f induced per conductor being 5 V. The generated voltage of the generator is ………….

  1. 60 V
  2. 250 V
  3. 360 V
  4. 1500 V
ANSWER
Answer: ( 2 )
EXPLANATION
Number of conductors per parallel path = 300/6 =  50. Hence the generator voltage = 50×5 = 250 V

28) For the same rating, DC machine has …………  an AC machine

  1. the same weight as
  2. more weight than
  3. less weight than
  4. none of the above
ANSWER
Answer: ( 2 )
EXPLANATION
No answer description required for this question.

29) The field winding of a DC shunt machine usually carries ………. of the rated current of the machine.

  1. less than 2%
  2. 2% to 5%
  3. 15% to 20%
  4. more than 20%
ANSWER
Answer: ( 2 )
EXPLANATION
No answer description required for this question.

30) A Separately excited generator is not used because …………

  1. it is costly
  2. separate DC source is required for field circuit
  3. voltage drops considerably with load
  4. none of the above
ANSWER
Answer: ( 2 )
EXPLANATION
No answer description required for this question.

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