Explore topic-wise MCQs in Electrical Machines.

This section includes 10 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.

IN_A_DC_GENERATOR,_THE_COMMUTATOR_SERVES_AS_A__________?$

A. mechanical rectifier for alternating EMF to direct EMF
B. mechanical inverter to invert the direct applied voltage to alternating voltage
C. any of the mentioned
D. none of the mentioned
Answer» B. mechanical inverter to invert the direct applied voltage to alternating voltage
2.

In a DC motor, the commutator serves as a ___________$

A. mechanical rectifier for alternating EMF to direct EMF
B. mechanical inverter to invert the direct applied voltage to alternating voltage
C. any of the mentioned
D. none of the mentioned
Answer» C. any of the mentioned
3.

In a DC machine, the pole core is usually of smaller cross section than the pole shoe because __________?

A. smaller cross section requires less copper
B. larger pole shoe increases the air gap reluctance
C. larger pole shoe increases the flux per pole entering the armature
D. larger pole shoe reduces the mechanical strength
Answer» D. larger pole shoe reduces the mechanical strength
4.

In larger DC machines, the reason behind using fabricated steel instead of cast iron in the manufacture of yoke is ?

A. economical considerations
B. permeability considerations
C. mechanical considerations
D. insulation considerations
Answer» C. mechanical considerations
5.

A synchronous machine can be connected to an energy system only when ___________

A. frequency/rotational speed matches
B. voltage matches
C. current matches
D. power matches
Answer» B. voltage matches
6.

In a synchronous generator, the frequency of the generated EMF depends on

A. rotational speed
B. poles
C. both rotational speed and poles
D. none of the mentioned
Answer» D. none of the mentioned
7.

For relatively large sizes of synchronous machines, which of the following are used for providing closed circuit cooling?

A. air
B. water
C. hydrogen/helium
D. any of the mentioned
Answer» E.
8.

Commercially, which of the following generators is called turbo-alternators or turbo-generators?

A. salient pole rotor synchronous generators
B. cylindrical pole rotor induction generators
C. salient pole rotor induction generators
D. cylindrical rotor synchronous generators
Answer» E.
9.

In a synchronous machine, cylindrical pole construction has been found to suit best for ___________

A. low speed prime movers
B. high speed prime movers
C. medium speed prime movers
D. any of the mentioned
Answer» C. medium speed prime movers
10.

How many poles should the alternators, driven by the steam and gas turbines prime movers must have, for better operation?

A. fewer number of poles
B. large number of poles
C. medium number of poles
D. any of the mentioned
Answer» B. large number of poles