Page 8 - Basics of Electrical, Electronic and Communication

xiv CONTENTS

7.8 Self excited dc generators . . . . . . . . . . . . . . . . 145
7.8.1 Shunt wound dc generator . . . . . . . . . . . 145
7.8.2 Series wound dc generator . . . . . . . . . . . 146
7.8.3 Compound wound dc generator . . . . . . . . 147
7.9 DC Motors . . . . . . . . . . . . . . . . . . . . . . . 152
7.9.1 Different types of dc motors . . . . . . . . . . 155
7.9.2 Applications of dc motors . . . . . . . . . . . 157

8 Three phase induction motor 159
8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . 159
8.2 Construction . . . . . . . . . . . . . . . . . . . . . . . 159
8.2.1 Stator . . . . . . . . . . . . . . . . . . . . . . 160
8.2.2 Rotor . . . . . . . . . . . . . . . . . . . . . . 160
8.3 Concept of rotating magnetic field . . . . . . . . . . . 162
8.3.1 Principle of operation of induction motors . . . 164
8.3.2 Slip of an Induction motor . . . . . . . . . . . 165
8.3.3 Applications of three phase induction motors . 167
8.3.4 Comparison of squirrel cage induction motor
and slip ring induction motor . . . . . . . . . . 168

9 Synchronous generators 171
9.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . 171
9.1.1 Construction . . . . . . . . . . . . . . . . . . 171
9.2 Principle of operation . . . . . . . . . . . . . . . . . . 174
9.2.1 EMF equation . . . . . . . . . . . . . . . . . 176

10 Power system 179
10.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . 179
10.2 Generation of electric power . . . . . . . . . . . . . . 179
10.3 Basic structure of AC power system . . . . . . . . . . 180
10.3.1 Typical power transmission scheme . . . . . . 181
10.4 Substations . . . . . . . . . . . . . . . . . . . . . . . 183

11 Electrical estimation 185
11.1 Electrical installations-estimating and costing of material185
11.1.1 Steps for estimation . . . . . . . . . . . . . . 185
11.1.2 Example of wiring installation in a room . . . 186

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