Page 12 - Electric Machinery Fundamentals

xii TABLE OF CONTENTS

Chapter 2 Transformers 65

2.1 Why Transformers Are Important to Modern Life 66
2.2 Types and Construction of Transformers 67
2.3 The Ideal Transformer 69
Power in an ldeal Transformer I Impedance Transformation
through a Transformer / Analysis of Circuits Containing
Ideal Transjomlers
2.4 Theory of Operation of Real Single-Phase Transformers 77
The Voltage Ratio across a Transformer I The
Magnetization Currelif in a Real Transjormer / The
Current Ratio on a Transformer and the Dot Convention
2.5 The Equivalent Circuit of a Transformer 86
The Exact. Equivalent Circuit of a Real Transformer /
Approximate Equivalent Circuits of a Transformer /
Determinin.g the Values of Components in the Transformer
Model
2.6 The Per-Unit System of Measurements 94
2.7 Transfonner Voltage Regulation and Efficiency 99
The Transformer Phasor Diagram / Transformer Efficiency
2.8 Transformer Taps and Voltage Regulation 108
2.9 The Autotransfonner 109
Voltage and Current Relationships in an Autotransfonner /
The Apparent Power Rating Advantage of Autotrallsfonners I
The Internal Impedance of an Autotransformer
2.10 Three-Phase Transformers 116
Three-Phase Transformer Connections I The Per-Unit
System for Three-Phase Transformers
2.11 Three-Phase Transformation Using 1\vo Transformers 126
The Open-I:! (or V-V) Connection I The Open-Wye-Open-
Delta Connection I The Scott-T Conflection I The Three-
Phase T Connection
2.12 Transfom1er Ratings and Related Problems 134
The Voltage and Frequency Ratings of a Transformer I The
Apparent Power Rating 0/ a Trans/ormer I The Problem oj
Current Inrllsh / The Transformer Nameplate
2.13 Instrument Transformers 140
2.14 Summary 142 r
Questions 143
Problems 144
References lSI