Electrical Machines - I

By Prof. Tapas Kumar Bhattacharya   |   IIT Kharagpur
Learners enrolled: 4753
Transformer and D.C rotating machine will be the main topics to be discussed in this course. Working principle of ideal transformer and its equivalent circuit referred to two sides. Analysis of practical transformer & its equivalent circuit. Equivalent circuit referred to different sides and phasor diagram. Core loss and copper loss. Regulation & efficiency. Three phase transformer connection & vector group. Parallel operation of transformers. Autotransformer. Basic constructional features of D.C machine. Elementary lap and wave winding used in armature. Emf and torque equations of D.C. machine – generator and motor mode. Armature reaction and its effect. Compensationg winding. Shunt, series and compound machines. Generator characteristics. Motor characteristics. Efficiency, Basic tests. INTENDED AUDIENCE: UG Electrical Engineering as core subject. UG Mechanical and Mining Engineering as Elective subject. PREREQUISITES: Basic Electrical Technology: Knowledge of elementary calculus INDUSTRY SUPPORT: BHEL, CESC, NTPC, WBPDCL
Course Status : Completed
Course Type : Core
Duration : 12 weeks
Category :
  • Electrical, Electronics and Communications Engineering
  • Power Systems and Power Electronics
Credit Points : 3
Level : Undergraduate
Start Date : 26 Jul 2021
End Date : 15 Oct 2021
Enrollment Ends : 09 Aug 2021
Exam Date : 24 Oct 2021 IST

Note: This exam date is subjected to change based on seat availability. You can check final exam date on your hall ticket.

Page Visits

Course layout

Week 1: Single phase Ideal transformer and basic equations. Its equivalent circuit. Week 2: Core loss: Eddy current and hysteresis loss – factors on which it depends. Week 3: Taking Leakage flux, winding resistances and core loss in the equivalent circuit of the transformer. Week 4: Exact and approximate equivalent circuit. Phasor diagram. Regulation & efficiency. Week 5: Open circuit and short circuit tests. Estimation of equivalent circuit parameters. Week 6: Three phase transformer and various connections with vector groups. Week 7: DC machine constructional features and basic idea of its operation. Armature winding, commutator segments and brushes. Week 8: Lap and wave windings and number of parallel paths in armature circuit. Emf equation. Week 9: Torque equation. Separately excited and shunt generator characteristics. Week 10: Armature reaction and its ill effects. How to nullify the effects of armature reaction. Week 11: Shunt, series and compound motor characteristic. Week 12: Starting, speed control and braking of DC motor. Testing.

Books and references

1. Electric Machinery Fundamentals 4th Edition by Stephen Chapman 2. Electrical Machinery 7th Edition P. S. Bimbhra 3. Electric Machines and Power System by Del Toro

Instructor bio

Prof. Tapas Kumar Bhattacharya

IIT Kharagpur
Tapas Kumar Bhattacharya has over thirty years of teaching experince at IIT Kharagpur. Taught signals & system core course at IIT Kharagpur several times.Area of research interest is in the field of electrical machines and special electrical machines and circuits..

Course certificate

The course is free to enroll and learn from. But if you want a certificate, you have to register and write the proctored exam conducted by us in person at any of the designated exam centres.
The exam is optional for a fee of Rs 1000/- (Rupees one thousand only).
Date and Time of Exams: 24 October 2021 Morning session 9am to 12 noon; Afternoon Session 2pm to 5pm.
Registration url: Announcements will be made when the registration form is open for registrations.
The online registration form has to be filled and the certification exam fee needs to be paid. More details will be made available when the exam registration form is published. If there are any changes, it will be mentioned then.
Please check the form for more details on the cities where the exams will be held, the conditions you agree to when you fill the form etc.


Average assignment score = 25% of average of best 8 assignments out of the total 12 assignments given in the course.
Exam score = 75% of the proctored certification exam score out of 100

Final score = Average assignment score + Exam score

YOU WILL BE ELIGIBLE FOR A CERTIFICATE ONLY IF AVERAGE ASSIGNMENT SCORE >=10/25 AND EXAM SCORE >= 30/75. If one of the 2 criteria is not met, you will not get the certificate even if the Final score >= 40/100.

Certificate will have your name, photograph and the score in the final exam with the breakup.It will have the logos of NPTEL and IIT Kharagpur .It will be e-verifiable at nptel.ac.in/noc.

Only the e-certificate will be made available. Hard copies will not be dispatched.

Once again, thanks for your interest in our online courses and certification. Happy learning.

- NPTEL team

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