Introduction to Machines
 
 
Subject Code: EPM1026
Aim of Subject: To introduce the basic concepts, general operating principles and construction of electrical machines.
Learning Outcome of Subject: At the completion of the subject, students should be able to:
  • Recognize the fundamental principles of electrical machines and three-phase systems.
  • Explain the construction, operation and applications of various generators, motors and transformers.
  • Distinguish the constructional details of induction machines and synchronous machines.
  • Construct the equivalent circuits and phasor diagrams for transformers and induction motors.
  • Analyse the torque-speed characteristics of three-phase induction motors.
Programme Outcomes:
  • Ability to acquire and apply fundamental principles of science and engineering. (60%)
  • Capability to communicate effectively. (10%)
  • Acquisition of technical competence in specialised areas of engineering discipline. (10%)
  • Ability to identify, formulate and model problems and find engineering solutions based on a systems approach. (10%)
  • Understanding and commitment to professional and ethical responsibilities. (5%)
  • Ability to work effectively as an individual, and as a member/leader in a team. (5%)
Assessment Scheme:
  • Lab Experiments - work in group of 2, lab report writing, oral assessment at the end of lab(10%)
  • Tutorial / Assignment - group assignment, focus group discussion at tutorial, to enhance understanding of basic concepts in lecture(10%)
  • Test Quiz - written exam(20%)
  • Final Exam - written exam(60%)
Teaching and Learning Activities: 53 hours (lectures, tutorials and laboratory experiments)
Credit Hours: 3
Pre-Requisite: ECT1016: Circuit Theory and
ECT1026: Field Theory
References:
  • S. J. Chapman, "Electric Machinery Fundamentals" – 4th edition, McGraw Hill Higher Education, 2004. (Textbook)
  • B.S. Guru and H.R. Hiziroglu, "Electric Machinery and Transformers"-3rd edition, Oxford University Press, 2001.
  • T. Wildi, "Electrical Machines, Drives, and Power Systems"-5th edition, Prentice Hall, 2002.
  • P.C. Sen, "Principle of Electric Machines and Power Electronics"-2nd edition, John Wiley & Sons, 1997.

Subject Contents

  • Introduction to Machinery Principles

  • Introduction to electrical machines and transformers. Rotational motion, Newton's law, and power relationships. Magnetic field, Fraday’s law, induced voltage on a conductor moving in a magnetic field, production of force on a wire in a magnetic field.
     
  • Three-phase Circuits

  • Three-phase systems. Relation between line and phase quantities. Analysis of Balanced three-phase circuits. Y-? transformation. Power and reactive power calculations.
     
  • D.C. Machines

  • Principles of operation and construction of DC machines, simple armature windings: lap and wave. Emf equation and principle of commutation. DC generators: Separately excited, shunt wound, series wound and compound wound generators. Conditions for self-excitation of shunt-generator. Load characteristics and voltage regulation. DC motors: Torque equation, characteristics of shunt, series and compound motors. Starting and speed control. Tests, measurement and efficiencies of DC machines.
     
  • Transformers

  • Single-phase transformers: Construction, principle of operation and equivalent circuit, phasor diagram, efficiency and regulation. Short and open circuit tests. Parallel operation. Three phase transformers: Construction, Connections, and Parallel operation Autotransformers, Instrument transformers.
     
  • Induction Machines

  • Principles of operation and construction of three-phase induction motor. Slip equation, equivalent circuit, determination of equivalent circuit parameters by no-load and blocked-rotor tests. Losses, efficiency and torque. Torque-speed characteristics, starting torque and maximum torque. Starting methods. Introduction to single-phase induction motors.
     
  • Synchronous Machines

  • Principle of operation of Synchronous generators, Synchronous impedance and equivalent circuit. Short-circuit and open-circuit tests. Voltage regulation. Synchronizing procedures and parallel operation of synchronous machines. Principle of operation of synchronous motors, starting methods.
     

Laboratory

1. Load Test on DC Motors
2. Single Phase Transformer