Electrical Machines (EE3283)

Pre-requisite(s)

Basic Electronics (EE-2223)

Recommended Book(s)

Electric Machinery Fundamentals by Stephan J. Chapman, 4th Ed.

Reference Book(s)

Electric Machines by Charles I. Hubert

Course Objectives

The main focus of this course is to understand the magnetic field, the reluctance of magnetic materials and air. The voltage-current characteristics, voltage regulation of DC generators, torque speed characteristics, speed regulation of DC motors and the generalized concepts of electromechanical energy conversion are included mainly in this course. Working principles, construction and operation of single phase and three phase transformers will be studied. This course includes AC machines fundamentals and production of rotating magnetic field. In this course working principles, construction, characteristics and equivalent circuit of three phase synchronous generators, synchronous motors and induction motors, Single phase and special purpose motors are discussed in detail.

Course Learning Outcomes (CLO)

CLO 1: Explain operating principles of fundamental components of Electric Machines: motors, generators and transformers including synchronous, asynchronous, DC and special purpose motors, AC, DC generators and autotransformers, CTs, PTs, step-up and step-down transformers. (Level: C2) 

CLO 2: Examine the magnetic field, reluctance of magnetic materials, flux and mmf in magnetic circuits and perform transformer analysis using standard testing procedures including open-circuit & short-circuit tests, voltage regulation, efficiency and circuit analysis involving transformers. (Level: C4)
CLO 3: Examine construction, working principles, characteristics and equivalent circuit of three phase synchronous generators, synchronous motors and induction motors, Single phase induction and special purpose motors. (Level: C4)
CLO 4: Analyze voltage-current characteristics, commutation of DC generators, torque speed characteristics and speed regulation of DC motors. (Level: C4)

Course Contents

DC Machines Topics

Introduction to Machinery Principles
  • Rotational motion
  • Newton’s Law and power relationships
  • The Magnetic field
  • Magnetic Circuit with air gap
  • Faraday’s law
  • Production of induced force on wire
  • Induced voltage on a conductor moving in a magnetic field
  • Linear DC machine 
DC Machinery Fundamentals
  • Simple rotating loop between curved pole faces
  • Commutation
  • Construction
  • Simple armature winding
  • Armature reaction
  • Interpoles, compensating winding and brush shifting
  • Internal generated voltage and induced torque equations of real machines
DC Generators
  • Introduction
  • Voltage regulation
  • Magnetization curve
  • Equivalent circuits
  • Working and characteristics of separately excited, shunt, series and compounded generators
  • Parallel operations of direct current generators
DC Motors
  • Introduction
  • Speed regulation
  • Equivalent Circuits
  • Working and Characteristics of separately excited, Shunt and Permanent magnet
  • Working and Characteristics of series and compounded motors
  • Torque–speed Equations
  • Efficiency calculations
  • Stepper Motor and Drive circuit 

AC Machines Topics

Transformer Fundamentals
  • Importance of transformers
  • Types and construction
  • The ideal transformer
  • Leakage reactance
  • Theory and operation of single phase transformer
  • Losses and phasor diagram
  • The equivalent circuit of a real transformer
  • No load and short circuit test
  • The per unit system
  • The transformer voltage regulation and efficiency
  • Tapping the autotransformer
  • Three phase Transformers
  • Construction of power Transformer
  • Three phase connections and harmonics suppression
  • Vector groups
  • Three phase transformer using two transformers
  • Transformer ratings and related problems
AC Machines Fundamentals
  • A simple loop in a uniform magnetic field
  • Review of three phase generation
  • The rotating magnetic field
  • The relationship between electrical and mechanical degree
  • The relationship between electrical frequency and the speed of the magnetic field rotation Induced voltage and induced torque
  • Losses and power flow diagram
  • Voltage regulation and speed regulation
Synchronous Generator
  • Construction
  • Excitation system
  • Equivalent circuit of Synchronous Generator
  • Phasor diagram, Power & Torque
  • Measurement of model parameters
  • Effect of load changes on a generator
  • Parallel operation of generators
Synchronous Motor
  • Basic principle of motor operation
  • Equivalent circuit
  • Torque speed characteristics
  • Power and torque equation
  • Phasor diagram
  • The effects of load change, and field current change
  • V-curves of synchronous motor & power factor correction
  • Starting of synchronous motor
  • Synchronous motor ratings 
Three Phase Induction Motor
  • Construction
  • Basic concepts and working principles
  • Synchronous speed
  • Slip and its effect on rotor frequency and rotor voltage
  • Equivalent circuit
  • Power and torque
  • Torque speed characteristics
  • losses, efficiency and power factor
Single Phase and Special Purpose Motors
  • The Universal motor
  • Introduction to single phase induction motor
  • Starting single phase induction motors
  • Split phase windings
  • Capacitor start motor
  • Permanent split capacitor motor
  • Capacitor start and capacitor run motors
  • Shaded pole motors
  • Reluctance motors
  • The Hysteresis motor

Mapping of CLOs to Program Learning Outcomes

CLOs/PLOs

CLO:1

CLO:2

CLO:3

 CLO:4

PLO:1 (Engineering Knowledge)

 

 

 

PLO:2 (Problem Analysis)

 

PLO:3 (Design and Development of Solutions)

 

 

 

 

PLO:4 (Investigation)

 

 

 

 

PLO:5 (Modern Tool Usage)

 

 

 

 

PLO:6 (The Engineer and Society)

 

 

 

 

PLO:7 (Environment and Sustainability)

 

 

 

 

PLO:8 (Ethics)

 

 

 

 

PLO:9 (Individual and Team Work)

 

 

 

 

PLO:10 (Communication)

 

 

 

 

PLO:11 (Project Management)

 

 

 

 

PLO:12 (Life Long Learning)