Title Transformer Engineering: Design and Practice 3.2 MB 478
```                            Transformer Engineering: Design and Practice
Foreword
Preface
ACKNOWLEDGMENTS
Contents
Appendix A: Fault Calculations
Appendix B: Stress and Capacitance Formulae
Chapter 1: Transformer Fundamentals
1.1 Perspective
1.2 Applications and Types of Transformers
1.3 Principles and Equivalent Circuit of a Transformer
1.3.1 Ideal transformer
1.3.2 Practical transformer
1.3.3 Mutual and leakage inductances
1.3.4 Simplified equivalent circuit
1.4 Representation of Transformer in Power System
1.5 Open Circuit and Short Circuit Tests
1.6 Voltage Regulation and Efficiency
1.7 Parallel Operation of Transformers
References
Appendix A: Fault Calculations
Appendix B: Stress and Capacitance Formulae
Chapter 2: Magnetic Characteristics
2.1 Construction
2.1.1 Types of core
2.1.2 Analysis of overlapping joints and building factor
2.2 Hysteresis and Eddy Losses
2.3 Excitation Characteristics
2.4 Over-Excitation Performance
2.5.1 Asymmetrical magnetizing phenomenon
2.5.2 Magnetic balance test
2.5.3 Trouble-shooting by no-load loss test
2.5.4 Effect of impulse test on no-load loss
2.6 Impact of Manufacturing Processes on Core Performance
2.7 Inrush Current
2.7.1 Theory
2.7.2 Estimation of magnitude of first peak
2.7.3 Estimation of decay pattern
2.7.4 Sympathetic inrush phenomenon
2.7.5 Factors affecting inrush phenomenon
A. Switching-on angle (Alpha)
B. Residual flux density
C. Series resistance
2.7.5 Mitigation of inrush current
2.8 Influence of Core Construction and Winding Connections on No-Load Harmonic Phenomenon
2.9 Transformer Noise
References
Appendix A: Fault Calculations
Appendix B: Stress and Capacitance Formulae
Chapter 3: Impedance Characteristics
3.1 Reactance Calculation
3.1.1 Concentric primary and secondary windings
3.1.2 Sandwich windings
3.1.3 Concentric windings with non-uniform distribution of ampere turns
3.2 Different Approaches for Reactance Calculation
3.3 Two-Dimensional Analytical Methods
3.3.1 Method of images
3.3.2 Roth’s method
3.3.3 Rabin’s method
3.4 Numerical Method for Reactance Calculation
1. Classical method
2. FEM analysis
1. Classical method
2. FEM analysis
3.5 Impedance Characteristics of Three-Winding Transformer
3.6 Reactance Calculation for Zigzag Transformer
3.7 Zero-Sequence Reactance Estimation
3.7.1 Open circuit zero-sequence reactance without delta connected winding
A. Three-phase three-limb transformers
B. Three-phase five-limb and single-phase three-limb transformers
3.7.2 Open circuit zero-sequence reactance with delta connected winding
A. Three-phase three-limb transformers
B. Three-phase five-limb and single-phase three-limb transformers
3.7.3 Short circuit zero-sequence reactance
A. Three-phase three-limb transformers
B. Three-phase five-limb and single-phase three-limb transformers
3.8 Stabilizing Tertiary Winding
References
Appendix A: Fault Calculations
Appendix B: Stress and Capacitance Formulae
Chapter 4: Eddy Currents and Winding Stray Losses
4.1 Field Equations
4.2 Poynting Vector
4.3 Eddy Current and Hysteresis Losses
4.4 Effect of Saturation
4.5 Eddy Loss in Transformer Winding
4.5.1 Expression for eddy loss
4.5.2 Methods of estimation
4.5.3 Optimization of losses and elimination of winding hot spots
4.5.4 Eddy loss in foil windings
4.6 Circulating Current Loss in Transformer Windings
4.6.1 Analytical methods
4.6.2 Method based on multi-winding transformer theory
4.6.3 FEM analysis
References
Appendix A: Fault Calculations
Appendix B: Stress and Capacitance Formulae
Chapter 5: Stray Losses in Structural Components
5.1 Factors Influencing Stray Losses
5.1.1 Type of surface excitation
5.1.2 Effect of load, temperature and frequency
5.2 Overview of Methods for Stray Loss Estimation
5.2.1 Two-dimensional methods
5.2.2 Three-dimensional analytical formulations
5.2.3 Three-dimensional numerical methods
5.3 Core Edge Loss
5.4 Stray Loss in Frames
5.5 Stray Loss in Flitch Plates
5.6 Stray Loss in Tank
5.7 Stray Loss in Bushing Mounting Plates
5.8 Evaluation of Stray Loss Due to High Current Leads
5.9 Measures for Stray Loss Control
5.9.1 Magnetic shielding
5.9.2 Eddy current shielding
5.10 Methods for Experimental Verification
5.10.2 Initial temperature rise
5.11 Estimation of Stray Losses in Overexcitation Condition
5.12.1 Half-turn effect
5.12.2 Single-phase load loss measurement on a three-phase transformer
References
Appendix A: Fault Calculations
Appendix B: Stress and Capacitance Formulae
Chapter 6: Short Circuit Stresses and Strength
6.1 Short Circuit Currents
6.2 Thermal Capability at Short Circuit
6.3 Short Circuit Forces
6.3.2 Axial forces
6.4 Dynamic Behavior Under Short Circuits
6.5 Failure Modes Due to Radial Forces
6.5.1 Winding subjected to tensile stresses
6.5.2 Windings subjected to compressive stresses
6.6 Failure Modes Due to Axial Forces
6.6.2 Tilting under an axial load
6.7 Effect of Pre-Stress
6.8 Short Circuit Test
6.9 Effect of Inrush Current
6.10 Split-Winding Transformers
6.11 Short Circuit Withstand
6.11.1 System configuration and transformer specification
6.11.2 Design
6.11.3 Manufacturing processes
6.12 Calculation of Electrodynamic Force Between Parallel Conductors
6.13 Design of Clamping Structures
Stresses in clamping ring
Stresses in flitch plates and frames
References
Appendix A: Fault Calculations
Appendix B: Stress and Capacitance Formulae
Chapter 7: Surge Phenomena in Transformers
7.1 Initial Voltage Distribution
7.2 Capacitance Calculations
7.3 Capacitance of Windings
7.3.1 Development of winding methods for better impulse response
7.3.2 Turn-to-turn and disk-to-disk capacitances
7.3.3 Continuous disk winding
7.3.4 Continuous winding with SER and SR
7.3.5 Interleaved winding
7.3.6 Shielded-conductor winding
7.3.7 Layer winding
7.3.8 Interleaved tap winding
7.4 Inductance Calculation
7.5 Standing Waves and Traveling Waves
7.6 Methods for Analysis of Impulse Distribution
7.7 Computation of Impulse Voltage Distribution Using State Variable Method
7.7.1 Derivation of differential equations
7.7.2 Formation of circumflex matrix
7.7.3 Formation of G matrix
7.7.4 Formation of … matrix
7.7.5 State space model
7.8 Winding Design for Reducing Internal Overvoltages
7.8.1 Part winding resonance
7.8.2 Natural frequencies of windings
7.8.4 Location of windings
References
Appendix A: Fault Calculations
Appendix B: Stress and Capacitance Formulae
Chapter 8: Insulation Design
8.1 Calculation of Stresses for Simple Configurations
8.2 Field Computations
8.2.1 Analytical methods
8.2.2 Numerical methods
8.3 Factors Affecting Insulation Strength
8.3.1 Effect of moisture and impurities
8.3.2 Effect of time and frequency
8.3.3 Effect of temperature
8.3.4 Effect of thickness
8.3.5 Stressed volume effects
8.3.6 Creepage phenomenon
8.3.7 Cumulative stress calculations
8.3.8 Effect of oil velocity
8.3.9 Processing of insulation
8.5 Insulation Between Two Windings
8.6 Internal Insulation
8.7 Design of End Insulation
8.9 Statistical Analysis for Optimization and Quality Enhancement
8.9.1 Parameter design
8.9.2 Tolerance design
References
Appendix A: Fault Calculations
Appendix B: Stress and Capacitance Formulae
Chapter 9: Cooling Systems
9.1 Modes of Heat Transfer
9.1.1 Conduction
9.1.3 Convection
9.2 Cooling Arrangements
9.2.1 ONAN/OA cooling
9.2.2 ONAF/FA cooling
9.2.3 OFAF/FOA cooling
9.2.4 Unit coolers
9.2.5 OFWF cooling
9.3 Dissipation of Core Heat
9.4 Dissipation of Winding Heat
9.5 Aging and Life Expectancy
9.6 Direct Hot Spot Measurement
9.7 Static Electrification Phenomenon
References
Appendix A: Fault Calculations
Appendix B: Stress and Capacitance Formulae
Chapter 10: Structural Design
10.1 Importance of Structural Design
10.2 Different Types of Loads and Tests
10.2.2 Tests
10.3 Classification of Transformer Tanks
10.4 Tank Design
10.5 Methods of Analysis
10.5.1 Analytical method
10.5.2 Numerical method
10.6 Overpressure Phenomenon in Transformers
10.7 Seismic Analysis
10.8 Transformer Noise: Characteristics and Reduction
10.8.2 Noise due to cooling equipment
10.8.3 Noise level reduction
10.8.4 Noise level measurement
References
Appendix A: Fault Calculations
Appendix B: Stress and Capacitance Formulae
Chapter 11: Special Transformers
11.1 Rectifier Transformers
11.1.1 Bridge connection
11.1.2 Interphase transformer connection
11.1.3 Features of rectifier transformers
11.2 Converter Transformers for HVDC
11.2.1 Configurations
11.2.2 Insulation design
11.2.3 Other design aspects
11.3 Furnace Transformers
11.4 Phase Shifting Transformers
References
Appendix A: Fault Calculations
Appendix B: Stress and Capacitance Formulae
Table of Conents
Chapter 12: Recent Trends in Transformer Technology
12.1 Magnetic Circuit
12.2 Windings
12.3 Insulation
12.4 Challenges in Design and Manufacture of Transformers
12.5 Computer-Aided Design and Analysis
12.6 Monitoring and Diagnostics
12.7 Life Assessment and Refurbishment
References
Appendix A: Fault Calculations
Appendix B: Stress and Capacitance Formulae
Table of Conents
Appendix A: Fault Calculations
A1 Asymmetrical Fault with No In-Feed from LV Side
A1.1 Delta connected tertiary winding is present
A1.2 Delta connected tertiary winding is absent
A2 Asymmetrical Fault with In-Feed from LV Side
A2.1 Delta connected tertiary winding is present
A2.2 Delta connected tertiary winding is absent
Appendix B: Stress and Capacitance Formulae
Table of Conents
Appendix B: Stress and Capacitance Formulae
B1 Stress Calculations
B2 Capacitance Calculations
B2.1 Capacitance between two parallel cylindrical conductors
B2.2 Capacitance of cylindrical conductor and plane at ground potential
Appendix A: Fault Calculations
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