Course Detail

16 Weeks

Electrical Machines I

Course Information

  • Level Undergraduate
  • Language English
  • Enrolled Colleges 35
  • Total Students 1360
  • Course Duration 16 Weeks
  • Course Start June 22, 2017


Electrical Machines I

This is a basic course on rotating electrical machines. This course covers the topics related to principles, performance, applications and design considerations of dc machines and transformers.


The knowledge of Advanced mathematics, Physics, Mechanics, Circuit Theory and Theory of electrical engineering.

Course Objectives:

Upon completion of this course, students will be able to do the following:

•Understand the unifying principles of electromagnetic energy conversion.
•Understand the construction, principle of operation and performance of DC machines.
•Learn the characteristics, performance, methods of speed control and testing methods of DC motors.
•To predetermine the performance of single phase transformers with equivalent circuit models.
•Understand the methods of testing of single-phase transformer.
•Analyze the three phase transformers and achieve three phase to two phase conversion.

Course Outcomes:

After completing this course the candidate should be able to:

•Able to assimilate the concepts of electromechanical energy conversion.
•Able to mitigate the ill-effects of armature reaction and improve commutation in dc machines.
•Able to understand the torque production mechanism and control the speed of dc motors.
• Able to analyze the performance of single phase transformers.
• Able to predetermine regulation, losses and efficiency of single phase transformers.
•Able to parallel transformers, control voltages with tap changing methods and achieve three-phase to two-phase transformation.


Unit 2

Performance of D.C. Machines:Torque and back-emf equations of dc motors– Armature reaction and commutation – characteristics of separately-excited, shunt, series and compound motors - losses and efficiency- applications of dc motors.

Unit 3

Starting, Speed Control and Testing of D.C. Machines:Necessity of starter – Starting by 3 point and 4 point starters – Speed control by armature voltage and field control – testing of DC machines - brake test, Swinburne’s method – principle of regenerative or Hopkinson’s method - retardation test -- separation of losses.

Unit 4

Single-phase Transformers:Types and constructional details - principle of operation - emf equation - operation on no load and on load – lagging, leading and unity power factors loads - phasor diagrams of transformers – equivalent circuit – regulation – losses and efficiency – effect of variation of frequency and supply voltage on losses – All day efficiency.

Unit 5

Single-phase Transformers Testing:Tests on single phase transformers – open circuit and short circuit tests – Sumpner’s test –separation of losses – parallel operation with equal voltage ratios – auto transformer -equivalent circuit – comparison with two winding transformers.

Unit 6

3-Phase Transformers:Polyphase connections - Y/Y, Y/Δ, Δ/Y, Δ/Δ and open Δ -- Third harmonics in phase voltages - three winding transformers: determination of Zp, Zs and Zt -- transients in switching - off load and on load tap changers -- Scott connection.