Electrical Machines Practice MCQ-2

Electrical Engineering Practice Test

Electrical Machines

1. In dc generator armature reaction is produced actually by

A) its field current
B) armature conductors
C) field poles
D) load current in armature

... Answer is D)

2. in a dc generator the effect of armature reaction on the main pole flux is to

A) reduce it
B) distort it
C) reverse it
D) both (a) and (b)

... Answer is D)

3. In a clockwise rotating loaded dc generator brushes have to be shifted

A) clock wise
B) counter clockwise
C) either A) or B)
D) neither A) or B)

... Answer is A)

4. The primary reason for proving compensating winding in dc genarator is to

A) compensate for decrease in main flux
B) neutralize armature mmf
C) neutralize cross magnetizing flux
D) maintain uniform flux distribution

... Answer is C)

5. shunt generators are most suited for stable parallel operation because of their voltage characteristics

A) identical
B)drooping
C) linear
D) rising

... Answer is B)

6. The main function of an equalizer bar is to make the parallel operation of two over compound dc generator

A) stable
B)possible
C)regular
D) smooth

... Answer is A)

7. Which one of the following types of generators does NOT need equalizers for satisfactory parallel operation

A) series
B)over compound
C)flat compound
D)under compound

... Answer is D)

8. The most likely causes of sparking at the brushes in dc machines is /are

A) open coil in the armature
B)defective interpoles
C)incorrect brush spring pressure
D)all of the above

... Answer is D)

9. The simplest way to shift load from one dc shunt generator running in parallel with another is to

A) adjust their field rheostats
B)insert resistances in their armature circuits
C)adjust speeds of their prime movers
D)use equalizer connections

... Answer is A)

10. the main factor which leads to unstable parallel operation of flat and over compound dc generator is

A) unequal number of turns in their series field winding
B)unequal series field resistances
C)their rising voltage characteristics
D)unequal speed regulation of their prime movers

... Answer is C)