Explore topic-wise MCQs in Electrical Machines.

This section includes 13 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.

Ideally the voltage regulation of an alternator should be ___________

A. zero
B. infinite
C. 50%
D. 100%
Answer» B. infinite
2.

If the emf from the air gap line is the 3-phase alternator is 440V per phase and armature current is 110 A. The synchronous reactance is?

A. 4 ohms
B. 2 ohms
C. 6.92 ohms
D. 2.32 ohms
Answer» B. 2 ohms
3.

In a calculation, the actual voltage regulation is 33.1% while the calculated value of the voltage regulation is 32.9%. This infers that the chosen method has been ___________

A. zpf or asa
B. emf
C. mmf
D. mmf or zpf
Answer» B. emf
4.

In a calculation, the actual voltage regulation is 33.1% while the calculated value of the voltage regulation is 25%. This infers that the chosen method has been ___________

A. emf
B. mmf
C. asa
D. zpf
Answer» C. asa
5.

In a calculation, the actual voltage regulation is 33.1% while the calculated value of the voltage regulation is 56.8%. This infers that the chosen method has been ___________

A. emf
B. mmf
C. asa
D. zpf
Answer» B. mmf
6.

The preferred order of calculating the voltage regulation is ___________

A. ZPF > ASA > MMF > EMF
B. ZPF > MMF > ASA > EMF
C. ASA > MMF > ASA > EMF
D. EMF > ASA > ZPF > MMF
Answer» B. ZPF > MMF > ASA > EMF
7.

Mmf method of voltage regulation is called _______ while the emf method is __________

A. optimistic, pessimistic
B. pessimistic, pessimistic
C. optimistic, optimistic
D. pessimistic, optimistic
Answer» B. pessimistic, pessimistic
8.

In mmf method ___________

A. all the emf is scaled to mmf
B. only the mmf values are considered neglecting impedance drop
C. all the emf are taken zero
D. emf is converted to saturated impedance drops
Answer» B. only the mmf values are considered neglecting impedance drop
9.

Emf method is also known as ___________

A. pessimistic method
B. optimistic method
C. zero power factor method
D. none of the mentioned
Answer» B. optimistic method
10.

The emf method of the voltage regulation is applicable only to cylindrical rotor alternator due to ___________

A. resultant air gap flux is not affected by angular position of rotor
B. uniform angular position of rotor
C. non uniform angular position of rotor
D. saliency of the poles is a trouble while estimating the emf
Answer» B. uniform angular position of rotor
11.

Alternator on infinite bus bar has constant ___________

A. terminal voltage and frequency
B. frequency
C. power factor
D. power factor and terminal voltage
Answer» B. frequency
12.

Voltage regulation for an alternator operating at leading power factor is negative due to ___________

A. magnetizing nature of armature reaction
B. demagnetizing nature of armature reaction
C. cross-magnetizing nature of armature reaction
D. all of the mentioned
Answer» B. demagnetizing nature of armature reaction
13.

When the load on an alternator is varied, its terminal voltage also changes due to _____________

A. armature resistance
B. leakage reactance
C. armature reaction
D. all of the mentioned
Answer» B. leakage reactance