Explore topic-wise MCQs in Electrical Machines.

This section includes 15 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.

If it is desired to approximate the efficiency of an induction motor operating at slip s , then its efficiency is given by?

A. 1-s/1+s
B. 1/1+s
C. s/s+1
D. s/1-s
Answer» B. 1/1+s
Discussion
2.

A delta connected capacitance bank is preferred over a star connected bank. This is done to ensure _________

A. lesser capacitance
B. easy calculation
C. easier connection
D. all of the mentioned
Answer» B. easy calculation
Discussion
3.

A star connected capacitor bank is connected to the induction motor having capacitance C and VA rating as VAs. If the capacitor bank is replaced by a delta bank then?

A. C = C/3, VA = VAs
B. C = 3C, VA = VAs
C. C = C, VA = VAs/3
D. C = C/3, VA = VAs/3
Answer» B. C = 3C, VA = VAs
Discussion
4.

Induction generators will deliver power at _________

A. leading p.f.
B. lagging p.f.
C. unity p.f.
D. zero p.f.
Answer» B. lagging p.f.
Discussion
5.

A 3-phase induction machine is running at super synchronous speed. For the machine to be self excited it _________

A. draws reactive power from mains
B. draws real power from mains
C. feeds reactive power to mains
D. generates emf by gradual voltage build up
Answer» B. draws real power from mains
Discussion
6.

In a 3-phase induction generator which is self excited, load has been increased. To keep the frequency of the generated voltage constant, speed of the induction machine should be _________

A. increased
B. decreased
C. maintained less than rated synchronous speed
D. maintained more than rated synchronous speed
Answer» B. decreased
Discussion
7.

The characteristics required of the three phase induction motor to match that of the load with the criteria of load torque inversely proportional to the shaft speed is?

A. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9a.png"><img alt="Graph for induction motor operating with load torque proportional to square - option a" class="alignnone size-full wp-image-161028" height="220" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9a.png" width="300"/></a>
B. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9b.png"><img alt="Graph for induction motor operating with load torque proportional to square - option b" class="alignnone size-full wp-image-161029" height="218" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9b.png" width="300"/></a>
C. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png"><img alt="Graph for induction motor operating with load torque proportional to square - option c" class="alignnone size-full wp-image-161031" height="235" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png" width="300"/></a>
D. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9d.png"><img alt="Graph for induction motor operating with load torque proportional to square - option d" class="alignnone size-full wp-image-161032" height="224" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9d.png" width="300"/></a>
Answer» E.
Discussion
8.

The characteristics required of the induction motor to match that of the load for load torque independent of the shaft speed is?

A. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9a.png"><img alt="Graph for induction motor operating with load torque proportional to square - option a" class="alignnone size-full wp-image-161028" height="220" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9a.png" width="300"/></a>
B. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9b.png"><img alt="Graph for induction motor operating with load torque proportional to square - option b" class="alignnone size-full wp-image-161029" height="218" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9b.png" width="300"/></a>
C. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png"><img alt="Graph for induction motor operating with load torque proportional to square - option c" class="alignnone size-full wp-image-161031" height="235" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png" width="300"/></a>
D. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9d.png"><img alt="Graph for induction motor operating with load torque proportional to square - option d" class="alignnone size-full wp-image-161032" height="224" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9d.png" width="300"/></a>
Answer» C. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png"><img alt="Graph for induction motor operating with load torque proportional to square - option c" class="alignnone size-full wp-image-161031" height="235" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png" width="300"/></a>
Discussion
9.

An induction motor is operating for the load with torque developed proportional to the shaft speed. The characteristics below is?

A. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9a.png"><img alt="Graph for induction motor operating with load torque proportional to square - option a" class="alignnone size-full wp-image-161028" height="220" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9a.png" width="300"/></a>
B. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9b.png"><img alt="Graph for induction motor operating with load torque proportional to square - option b" class="alignnone size-full wp-image-161029" height="218" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9b.png" width="300"/></a>
C. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png"><img alt="Graph for induction motor operating with load torque proportional to square - option c" class="alignnone size-full wp-image-161031" height="235" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png" width="300"/></a>
D. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9d.png"><img alt="Graph for induction motor operating with load torque proportional to square - option d" class="alignnone size-full wp-image-161032" height="224" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9d.png" width="300"/></a>
Answer» C. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png"><img alt="Graph for induction motor operating with load torque proportional to square - option c" class="alignnone size-full wp-image-161031" height="235" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png" width="300"/></a>
Discussion
10.

The graph for the induction motor operating with load torque proportional to square of the shaft speed.

A. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9a.png"><img alt="Graph for induction motor operating with load torque proportional to square - option a" class="alignnone size-full wp-image-161028" height="220" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9a.png" width="300"/></a>
B. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9b.png"><img alt="Graph for induction motor operating with load torque proportional to square - option b" class="alignnone size-full wp-image-161029" height="218" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9b.png" width="300"/></a>
C. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png"><img alt="Graph for induction motor operating with load torque proportional to square - option c" class="alignnone size-full wp-image-161031" height="235" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png" width="300"/></a>
D. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9d.png"><img alt="Graph for induction motor operating with load torque proportional to square - option d" class="alignnone size-full wp-image-161032" height="224" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9d.png" width="300"/></a>
Answer» B. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9b.png"><img alt="Graph for induction motor operating with load torque proportional to square - option b" class="alignnone size-full wp-image-161029" height="218" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9b.png" width="300"/></a>
Discussion
11.

At standstill the equivalent of the 3-phase induction motor is similar to _________

A. short-circuited two winding transformer
B. open circuit two winding transformer
C. stand still synchronous motor
D. none of the mentioned
Answer» B. open circuit two winding transformer
Discussion
12.

The actual rotor resistance referred to the stator if the induction motor is?

A. r2
B. (r2)/s
C. (r2)/(1-s)
D. (r2)*(1-s)/s
Answer» B. (r2)/s
Discussion
13.

The electrical anlogous of the mechanical load in the induction machine is given by?

A. (r2)*(1-s)/s
B. (r2)
C. (r2)/s
D. (r2)/(1-s)
Answer» B. (r2)
Discussion
14.

The actual rotor equivalent of an induction motor is best depicted by?

A. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1a.png"><img alt="The equivalent circuit for polyphase induction motor - option a" class="alignnone size-full wp-image-161021" height="159" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1a.png" width="300"/></a>
B. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1b.png"><img alt="The equivalent circuit for polyphase induction motor - option b" class="alignnone size-full wp-image-161022" height="198" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1b.png" width="294"/></a>
C. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1c.png"><img alt="The equivalent circuit for polyphase induction motor - option c" class="alignnone size-full wp-image-161023" height="106" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1c.png" width="300"/></a>
D. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1d.png"><img alt="The equivalent circuit for polyphase induction motor - option d" class="alignnone size-full wp-image-161024" height="119" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1d.png" width="300"/></a>
Answer» C. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1c.png"><img alt="The equivalent circuit for polyphase induction motor - option c" class="alignnone size-full wp-image-161023" height="106" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1c.png" width="300"/></a>
Discussion
15.

Stator equivalent circuit for polyphase induction motor is?

A. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1a.png"><img alt="The equivalent circuit for polyphase induction motor - option a" class="alignnone size-full wp-image-161021" height="159" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1a.png" width="300"/></a>
B. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1b.png"><img alt="The equivalent circuit for polyphase induction motor - option b" class="alignnone size-full wp-image-161022" height="198" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1b.png" width="294"/></a>
C. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1c.png"><img alt="The equivalent circuit for polyphase induction motor - option c" class="alignnone size-full wp-image-161023" height="106" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1c.png" width="300"/></a>
D. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1d.png"><img alt="The equivalent circuit for polyphase induction motor - option d" class="alignnone size-full wp-image-161024" height="119" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1d.png" width="300"/></a>
Answer» B. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1b.png"><img alt="The equivalent circuit for polyphase induction motor - option b" class="alignnone size-full wp-image-161022" height="198" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1b.png" width="294"/></a>
Discussion