Explore topic-wise MCQs in Electrical Machines.

This section includes 20 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Machines knowledge and support exam preparation. Choose a topic below to get started.

1.

_____________ is responsible for mechanical power output of a DC motor.

A. Electrical input power
B. Any of the mentioned
C. Air-gap flux
D. Armature emf
Answer» B. Any of the mentioned
Discussion
2.

A dc series generator as armature and field connections are reversed, the generator __________

A. stops
B. opposite direction
C. same direction
D. none of the mentioned
Answer» B. opposite direction
Discussion
3.

The number of parallel paths in the armature is increased by __________

A. increasing number of magnetic poles
B. decreasing number of magnetic poles
C. lap number of magnetic poles
D. using more brushes
Answer» B. decreasing number of magnetic poles
Discussion
4.

A series generator, having external characteristics which is a straight line through 0 to 50 V at 200 A is connected as a booster, between a station bus-bar and feeders of 0.5 ohm resistors. The voltage at the far end of feeder at current of 50 A is?

A. 25 V
B. 17 V
C. 8 V
D. 50 V
Answer» B. 17 V
Discussion
5.

Flashing is used to __________

A. temporarily excited field from a battery source for large DC generator
B. temporarily excited field from a battery source for small DC generator
C. temporarily excited field from a battery source for large DC motor
D. temporarily excited field from a battery source for large DC motor
Answer» B. temporarily excited field from a battery source for small DC generator
Discussion
6.

If a DC shunt generator fails to start, the most primitive action would be __________

A. reversing field connection to armature
B. reversing direction of rotation
C. any of the mentioned applicable ways
D. none of the mentioned
Answer» B. reversing direction of rotation
Discussion
7.

The critical resistance refers to __________

A. the resistance above which machine does not excite
B. the resistance below which machine does not excite
C. the resistance at which machine does not excite
D. any of the mentioned
Answer» B. the resistance below which machine does not excite
Discussion
8.

The self-excited dc generator with gradual build up of residual voltage and EMF corresponds to __________

A. positive feedback
B. negative feedback
C. saturation
D. any of the mentioned
Answer» B. negative feedback
Discussion
9.

If a self excited DC generator is failed to run, this refers to ________________

A. zero residual voltage
B. field MMF, that it is not cumulative
C. resistance is greater than critical resistance
D. any of the mentioned
Answer» B. field MMF, that it is not cumulative
Discussion
10.

Consider a DC generator running at the rated speed of 2000 rpm, suddenly there is an insulator falls on the field circuit and breaks it. Then __________

A. the motor stops in a few rounds
B. it continues to run but as dc motor
C. it continues to run as a motor
D. none of the mentioned
Answer» B. it continues to run but as dc motor
Discussion
11.

A_DC_SERIES_GENERATOR_AS_ARMATURE_AND_FIELD_CONNECTIONS_ARE_REVERSED,_THE_GENERATOR?$

A. stops
B. opposite direction
C. same direction
D. none of the mentioned
Answer» B. opposite direction
Discussion
12.

____ is responsible for mechanical power output of a DC motor$

A. Electrical input power
B. Any of the mentioned
C. Air-gap flux
D. Armature emf
Answer» B. Any of the mentioned
Discussion
13.

The number of parallel paths in the armature is increased b?

A. increasing number of magnetic poles
B. decreasing number of magnetic poles
C. lap number of magnetic poles
D. using more brushes
Answer» B. decreasing number of magnetic poles
Discussion
14.

A series generator, having external characteristics which is a straight line through 0 to 50 V at 200 A is connected as a booster, between a station bus-bar and feeders of 0.5 ohm resistors. The voltage at the far end of feeder at current of 50 A is

A. 25 V
B. 17 V
C. 8 V
D. 50 V
Answer» B. 17 V
Discussion
15.

Flashing is used to

A. temporarily excited field from a battery source for large DC generator
B. temporarily excited field from a battery source for small DC generator
C. temporarily excited field from a battery source for large DC motor
D. temporarily excited field from a battery source for large DC motor
Answer» B. temporarily excited field from a battery source for small DC generator
Discussion
16.

If a DC shunt generator fails to start, the most primitive action would be

A. reversing field connection to armature
B. reversing direction of rotation
C. any of the mentioned applicable ways
D. none of the mentioned
Answer» B. reversing direction of rotation
Discussion
17.

The critical resistance refers to

A. the resistance above which machine does not excite
B. the resistance below which machine does not excite
C. the resistance at which machine does not excite
D. any of the mentioned
Answer» B. the resistance below which machine does not excite
Discussion
18.

The self-excited dc generator with gradual build up of residual voltage and EMF corresponds to

A. positive feedback
B. negative feedback
C. saturation
D. any of the mentioned
Answer» B. negative feedback
Discussion
19.

If a self excited DC generator is failed to run, this refers to

A. zero residual voltage
B. field MMF, that it is not cumulative
C. resistance is greater than critical resistance
D. any of the mentioned
Answer» B. field MMF, that it is not cumulative
Discussion
20.

Consider a DC generator running at the rated speed of 2000 rpm, suddenly there is an insulator falls on the field circuit and breaks it. Then

A. the motor stops in a few rounds
B. it continues to run, but as dc motor
C. it continues to run as a motor
D. none of the mentioned
Answer» B. it continues to run, but as dc motor
Discussion