Induction Machines Questions and Answers: 20 MCQs Induction Machine, useful for all competitive exams of electrical Engineering.
Join EEE Made Easy Whatsapp Channel
1. For the production of a rotating magnetic field using stationary windings, we must connect
(a) a single-phase supply to a single-phase winding
(b) a three-phase supply to a three-phase winding
(c) a single-phase supply to a two-phase winding
(d) either a single-phase winding or a two-phase winding to a single-phase supply.
2. When a three-phase 50 Hz, 400 V supply is applied across a four-pole, three-phase winding, a rotating magnetic field is produced which is rotating at
(a) 200 rpm (b) 1600 rpm
(c) 1500 rpm (d) 3000 rpm.
3. A four-pole, three-phase induction motor is rotating at 1440 rpm when a 400 V, 50 Hz supply is
applied to its stator terminals. The slip of the motor expressed in percentage is
(a) 4 per cent (b) 2 per cent
(c) 5 per cent (d) 6 per cent.
4. The synchronous speed Ns, frequency f, and number of poles, P are related as
(a) Ns = 120P/f
(b) Ns = 120f/P
(c) Ns =f P/120
(d) Pf/60
5. When an induction motor is yet to start, i.e., at standstill, its slip is
(a) 0 (b) 1
(c) infinity (d) near to 0.
6. The speed of a three-phase induction motor when supplied with three-phase, 400 V, 50 Hz supply
is 1440 rpm. The number of poles for which the windings are made must be
(a) 2 (b) 4
(c) 6 (d) 8.
7. A three-phase induction motor develops a torque of 500 Nm at normal supply voltage. If the supply
voltage is reduced to half, what will be the torque developed?
(a) 250 Nm
(b) 125 Nm
(c) will remain constant at 500 Nm
(d) 62.5 Nm.
8. The slip of an induction motor can be expressed as
(a) S= (Nr – Ns) / Nr
(b) S =(Ns – Nr) /Nr
(c) S= (Ns – Nr) / Ns
(d) s= Nr/ (Ns – Nr)
9. A four-pole, 50 Hz, 400 V, three-phase induction motor is running at 1440 rpm. The frequency of
rotor-induced EMF is
(a) 2 Hz (b) 4 Hz
(c) 1 Hz (d) 50 Hz.
10. A four-pole, three-phase induction motor when fed from a 400 V, 50 Hz supply, runs at 1440 rpm. The frequency of EMF induced in the rotor is
(a) 2 Hz (b) 45 Hz
(c) 50 Hz (d) 3 Hz.
11. If an induction motor by some means is rotated at synchronous speed, then
(a) the EMF induced in the rotor will be maximum
(b) the EMF induced in the rotor will be zero
(c) the torque developed by the rotor will be maximum
(d) the frequency of induced EMF will be slip times the supply frequency.
12. Increase in the rotor-circuit resistance of an induction motor will
(a) increase the starting torque
(b) decrease the starting torque
(c) increase the maximum torque developed
(d) decrease the maximum torque developed.
13. Torque developed by a three-phase induction motor depends on
(a) the supply voltage
(b) the rotor-circuit resistance
(c) the slip of the rotor
(d) all the above.
14. A large capacity three-phase induction motor is started using a star–delta starter instead of starting
direct-on-line. The starting current
(a) is increased three times
(b) remains constant
(c) is reduced to one-third its value
(d) is reduced to half its value.
15. With rotor-circuit resistance, R2 of 2 W, the maximum torque of an induction motor is developed
at 10 percent slip. When the maximum torque is developed at 20 percent slip, the value of R2 will be
(a) 1 W (b) 2 W
(c) 0.5 W (d) 4 W.
16. The speed of a three-phase slip-ring-type induction motor can be controlled by
(a) changing the frequency of supply voltage to the motor
(b) changing the rotor-circuit resistance
(c) changing the number of poles
(d) all the methods as in (a), (b) and (c).
17. The four no-load speeds of three-phase induction motors operating on 400 V, 50 Hz supply are 576 rpm, 720 rpm, 1440 rpm, and 2880 rpm. The number of poles of the motor, respectively, are
(a) 8, 6, 4, 2 (b) 10, 8, 4, 2
(c) 12, 8, 4, 2 (d) 16, 8, 4, 2.
18. The power factor of a three-phase induction motor on no load is found to be 0.15 lagging. When the motor is fully loaded its power factor would be around
(a) 0.05 lagging (b) 0.15 lagging
(c) 0.85 lagging (d) 0.85 leading.
19. The three supply terminals R, Y, B when connected, respectively, to the three stator terminals
a, b, c of a three-phase induction motor, the motor rotates in the clockwise direction. The motor will
rotate in the reverse direction if
(a) R is connected to c, Y is connected to a, and B is connected to b
(b) R is connected to b, Y is connected to a, connection of B to c remains unchanged
(c) the supply voltage is reduced to half its value
(d) the frequency of supply is gradually reduced.
20. A three-phase induction motor has standstill rotor circuit resistance, X20 of 8 W and resistance of 2 W. The maximum torque will be developed at starting if the circuit parameters are
(a) R2 = 2 Ω, X20 = 4 Ω
(b) R2 = 4 Ω, X20 = 8 Ω
(c) R2 = 8 Ω, X20 = 8 Ω
(d) R2 = 16 Ω, X20 = 8 Ω.
1. (b) 2. (c) 3. (a) 4. (b) 5. (b) 6. (b) 7. (b) 8. (c) 9. (a) 10. (d) 11. (b) 12. (a) 13. (d) 14. (c) 15. (d) 16. (d) 17. (b) 18. (c) 19. (b) 20. (c)
Join EEE Made Easy Whatsapp Channel
Join EEE Made Easy Telegram channel
| Basic Electrical Engineering MCQ’s From Notebook Site (www.notebukofaprofessor.blogspot.com) |
| 1. Basic Electrical Engineering MCQ 1 |
| 2. Current Electricity MCQ |
| 3. Basic Electrical MCQ 2 |
| 4. Basic Electrical Engineering MCQ 3 |
| 5. Basic Electrical Engineering MCQ 4 |
| 6. Basic Electrical Engineering MCQ 5 |
| 7. Basic Electrical Engineering MCQ 6 |
| 8. Basic Electrical Engineering MCQ 7 |
| 9. Basic Electrical Engineering MCQ 8 |
| 10. Basic Electrical Engineering MCQ 9 |
| 11. Basic Electrical Engineering MCQ 10 |
| 12. Basic Electrical Engineering MCQ 11 |
| 13. Basic Electrical Engineering MCQ 2 |
| 14. Basic Electrical Engineering MCQ 14 |
Electrical Machines Best Books
| Sl no. | Book Title | Author | Buy Link |
|---|---|---|---|
| 1 | Textbook Of Electrical Technology : Ac And Dc Machines (volume – 2) | B L Theraja, AK Theraja | check price |
| 2 | Theory & Performance of Electrical Machines | J.B. Gupta | check price |
| 3 | Electrical Machines | by V.K Mehta, Rohit Mehta | check price |
| 4 | Electric Machines | PS Bimbhra | check price |
| 5 | Electrical Machines | S.K. Bhattacharya | check price |
1.Single Phase Induction Motor MCQ | EEE Made Easy Objective Questions|Sub Engineer KSEB
2. Single Phase Synchronous Motor MCQs|Assistant Electrical Inspector,AE, Electrician
3. Reluctance Motor & Hysteresis Motor|Single phase Synchronous Motor
4. How do an induction cooker work?
Download EEE Made Easy Ebook PDF Free
Latest Posts in EEE Made Easy
- Syllabus Training Instructor Plumber|14/2025 Syllabus Kerala PSCSyllabus Training Instructor Plumber: 14/2025 Syllabus Kerala PSC. Download the syllabus and Previous question papers for the Training Instructor in … Read more
- [PDF] Syllabus AE KSEB Transfer|378/2025 Syllabus Kerala PSCSyllabus AE KSEB Transfer: DETAILED SYLLABUS FOR THE POST OF ASSISTANT ENGINEER(ELECTRICAL) (Kerala State Electricity Board Ltd.) – By Transfer … Read more
- Modified Harvard Architecture
Modified Harvard Architecture: One of the ways by which the number of clock cycles required for the memory access can … Read more - TMS320C5X ArchitectureTMS320C5X Architecture:The TMS320 DSP family consists of two types of single-chip DSPs: 16-bit fixed-point and 32-bit floating-point. These DSPs possess … Read more
- Advantages of Digital Signal ProcessingAdvantages of Digital Signal Processing: Advantages of DSP are Ease of Processing, Thermal Drift and Reliability, Repeatability, Immunity to Noise, … Read more
- [PDF] AE Agro Industries Corporation syllabus|595/2024 syllabus Kerala PSCAE Agro Industries Corporation syllabus: 595/2024 syllabus Kerala PSC: DETAILED SYLLABUS FOR THE POST OF ASSISTANT ENGINEER- THE KERALA AGRO … Read more
- Tellengen’s Theorem & ExampleTellengen’s Theorem: What is Tellengen’s theorem? Tellengen’s Theorem In any arbitrary network, the algebraic sum of the powers in all … Read more
