Cover image for Power transformers : principles and applications
Title:
Power transformers : principles and applications
Author:
Winders, John J., 1947-
Personal Author:
Publication Information:
New York : Marcel Dekker, [2002]

©2002
Physical Description:
xiii, 283 pages : illustrations ; 24 cm.
Language:
English
Subject Term:
ISBN:
9780824707668
Format :
Book

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TK2551 .W495 2002 Adult Non-Fiction Non-Fiction Area
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Summary

Summary

Complete with equations, illustrations, and tables, this book covers the basic theory of electric power transformers, its application to transformer designs, and their application in utility and industrial power systems. The author presents the principles of the two-winding transformer and its connection to polyphase systems, the origins of transformer losses, autotransformers, and three-winding transformers and compares different types of transformer coil and coil construction. He describes the effects of short circuits on transformers, the design and maintenance of ancillary equipment, and preventative and predictive maintenance practices for extending transformer life.


Author Notes

John J. Winders, Jr. is Senior Engineer at PPL Electric Utilities, Allentown, Pennsylvania.


Table of Contents

H. Lee Willis
Series Introductionp. iii
Prefacep. v
1 Basic Transformer Theoryp. 1
1.1 Definition of a Transformerp. 1
1.2 Magnetic Units and Conversion Factorsp. 1
1.3 Currents and Magnetic Fieldsp. 3
1.4 Magnetic Inductionp. 4
1.5 Constructing a Simple Transformerp. 5
1.6 The Magnetic Circuitp. 6
1.7 The B-H Curvep. 10
1.8 The B-H Curve and Hysteresisp. 11
1.9 Magnetizing Currents and Harmonicsp. 15
1.10 Transformer Core Design and Constructionp. 16
1.11 Magnetostrictionp. 20
1.12 Completing the Transformer by Adding a Second Windingp. 20
1.13 Placement of the Windingsp. 22
Referencesp. 24
2 Two-Winding Transformer Connectionsp. 25
2.1 Introductionp. 25
2.2 The Y-Y Connection in Three-Phase Systemsp. 26
2.3 Advantages of the Y-Y Connectionp. 29
2.4 Disadvantages of the Y-Y Connectionp. 30
2.5 The Y-[Delta] Connection and the [Delta]-Y Connectionp. 33
2.6 Phase Angle Displacement and Phase Rotationp. 36
2.7 The Y-[Delta] Grounding Bankp. 40
2.8 The Zigzag Connectionp. 42
2.9 Comparisons of Economy of the Different Winding Configurationsp. 44
2.10 Trade-Off Between Steel and Copper in the Design of a Transformerp. 47
2.11 Connecting Three-Phase Banks Using Single-Phase Transformersp. 48
2.12 Transforming Three-Phase Voltages into Two-Phase Voltagesp. 50
2.13 The Scott Transformer Connectionp. 51
2.14 Three-Phase Transformer Designsp. 56
2.15 Standard Terminal Markings for Transformersp. 62
Referencesp. 67
3 Transformer Impedance and Lossesp. 69
3.1 Leakage Flux and Leakage Reactancep. 69
3.2 Conductor Lossesp. 74
3.3 No-Load Lossesp. 76
3.4 Magnetizing Reactancep. 79
3.5 Equivalent Circuit of a Two-Winding Transformerp. 80
3.6 A Brief Tutorial on Symmetrical Componentsp. 81
3.7 Transformer Equivalent Circuits Modeled in Zero Phase Sequence Networksp. 85
3.8 Series Impedance and Regulationp. 92
3.9 Matching Transformers for Parallel and Bank Operationsp. 93
3.10 Impedance Mismatch in Three-Phase Transformer Banksp. 95
3.11 Temperature Rise and the Thermal Capabilityp. 98
3.12 Interpreting Transformer Test Reportsp. 99
3.13 Calculating the Hot-Spot Temperature Using the IEEE Methodp. 102
3.14 Calculating the Loss of Lifep. 105
Referencesp. 116
4 Autotransformers and Three-Winding Transformersp. 117
4.1 Autotransformer Connectionsp. 117
4.2 Impedance of an Autotransformerp. 122
4.3 Limitations of the Autotransformer Connectionp. 128
4.4 Autotransformer Voltages with Short Circuits Appliedp. 129
4.5 Impulse Voltages Applied to Autotransformersp. 131
4.6 Autotransformer Core and Coil Designs and Terminal Configurationsp. 131
4.7 Advantages and Disadvantages of the Autotransformer Connectionp. 132
4.8 Three-Winding Transformersp. 133
4.9 Modification of Transformer Laws with Three Windingsp. 134
4.10 Equivalent Circuit of a Three-Winding Transformerp. 136
4.11 Core and Coil Construction of Three-Winding Transformersp. 138
4.12 Thermal Capability of Three-Winding Transformersp. 141
4.13 The Stabilizing Effect of a [Delta] Tertiary Windingp. 141
Referencep. 146
5 Short Circuits, Inrush Currents, and Other Phenomenap. 147
5.1 Effects of Short Circuits on Transformersp. 147
5.2 Comparisons of Short-Circuit Currents for Various Faultsp. 148
5.3 Mechanical Forces in Transformersp. 155
5.4 Forces between Transformer Windingsp. 158
5.5 Short-Circuit Forces in Three-Winding Transformersp. 163
5.6 Exciting Current Inrushp. 165
5.7 Tank Overheating from Zero-Sequence Currentsp. 169
5.8 Primary Fuse Misoperationsp. 172
5.9 Ferroresonancep. 175
5.10 Voltage Surgesp. 177
Referencesp. 187
6 Ancillary Equipmentp. 189
6.1 Bushingsp. 189
6.2 Oil Preservation Systemsp. 192
6.3 Cooling Equipmentp. 196
6.4 Temperature, Oil Level, and Pressure Gaugesp. 201
6.5 Tap-Changing Equipmentp. 202
6.6 Load Tap Changersp. 204
6.7 Voltage Regulating Transformersp. 209
6.8 Tap Changer Automatic Controlsp. 210
6.9 Variable Phase Shifting Transformersp. 212
Referencep. 220
7 Reading and Applying Nameplate Informationp. 221
7.1 Minimum Nameplate Requirementsp. 221
7.2 Manufacturer's Informationp. 223
7.3 Cooling Class, Number of Phases, and Operating Frequencyp. 223
7.4 Voltage Ratingsp. 224
7.5 KVA or MVA Ratingsp. 225
7.6 Winding Connection Diagramp. 226
7.7 Phasor or Vector Diagramp. 229
7.8 Weights and Oil Capacityp. 229
7.9 Operating Pressure Rangep. 230
7.10 Impedancep. 231
7.11 Basic Insulation Levelp. 232
7.12 Nameplate Layoutp. 233
Referencesp. 233
8 Maintenance, Testing, Troubleshooting, and Reliabilityp. 235
8.1 Good Utility Practicesp. 235
8.2 Preventative Maintenance versus Predictive Maintenancep. 252
8.3 Factory Testsp. 252
8.4 Ratio Testp. 252
8.5 Other Factory Testsp. 255
8.6 Field Testsp. 258
8.7 Gas-in-Oil Analysisp. 261
8.8 Water-in-Oil Analysisp. 265
8.9 Drying Transformersp. 268
8.10 Oil Dielectric Testp. 268
8.11 Reliability Calculationsp. 269
8.12 The Chi-Squared Distributionp. 269
8.13 The Poisson Distributionp. 271
8.14 Statistical Economicsp. 273
Referencesp. 275
Indexp. 277