Cover
Half Title
Title Page
Copyright Page
Table of Contents
Preface
Acknowledgments
Author
Chapter 1 Transformer Design
1.1 Introduction
1.2 Definition of Transformer
1.3 Design Objectives
1.4 Basic Theory of Transformer
1.4.1 Electromagnetic Terms and Concepts
1.4.2 Charges, Electric Field and Magnetic Field
1.4.3 Maxwellβs Equations
1.5 Power Transfer Capacity of Transformer
Chapter 2 Brief History of Transformers and the Emerging Trends
2.1 Brief History of the Transformer
2.2 Development of Materials for Transformer production
2.2.1 Conducting Material
2.2.2 Cooling Medium
2.2.3 Magnetic Material (Electrical Steel)
2.2.4 New and Emerging Technologies
2.2.5 New Technologies in Commercial Use
2.2.5.1 Amorphous Core Transformers
2.2.5.2 Symmetrical Wound Core (3D Core) Transformer
2.2.5.3 Biodegradable Oil-Filled Transformer
2.2.5.4 Gas-Insulated Transformers
2.2.6 Application of Emerging Technologies to Transformer Design and Manufacture ??
2.2.6.1 Transformers Using High-Temperature Superconductors
2.2.6.2 Intelligent Transformer for Smart Grid
2.3 Replacement of Copper/Aluminium by Carbon Nanotube
2.4 Use of Artificial Intelligence (AI) for Transformer Design and Diagnostics
2.5 Use of Additive Manufacturing (3D Printing) for Transformer Production
Chapter 3 Design Procedures
3.1 Design Input Data
3.2 Design Flow Chart [For Design with LV Parallel Conductors and HV Layer Windings]
Chapter 4 Core Design: Core Area Calculation
4.1 Calculation of Core Diameter and Core Area
4.1.1 Selection of Core Circle
4.1.2 Selection of Core Step Widths
4.1.2.1 Optimum Width of Core Steps to Get Maximum Core Area
4.1.3 Calculation of Gross Area and Net Area of Core
Chapter 5 Winding Design
5.1 Calculation of Volts per Turn
5.2 Calculation of Phase Volts and Phase Currents
5.3 Calculation of Number of Turns
5.3.1 Calculation of Voltage and Turns of Extended Delta Winding
5.3.2 Calculation of Tap Turns
5.3.2.1 Categories of Voltage Variation
5.4 Calculation of the Cross Section Area of Conductor
5.5 Selection of Current Density
5.6 Selection of Conductor Sizes
5.7 Selection of Types of Windings
5.8 Tap CHANGERS and Tap Changer Connections
5.8.1 Off-Circuit Tap Changer
5.8.2 Off-Load Tap Changer
5.8.3 On-Load Tap Changer
5.9 Calculation of Axial Height of Winding
5.9.1 Spiral Winding
5.9.2 Foil Winding
5.9.3 Crossover Coils
5.9.4 Disc Winding
5.10 Electrical Clearances of Oil-Filled Three-Phase Transformers
5.11 Calculation of Electrical Stresses for Different Configurations
5.11.1 Two Bare Uniform Electrodes (Parallel Electrodes) (One Dielectric) ?
5.11.2 Multidielectric (Parallel Electrodes)
5.11.3 Concentric Cylindrical Electrodes (One Dielectric)
5.11.4 Concentric Cylindrical Electrodes with Multiple Dielectrics
5.11.5 Cylindrical Conductor to Plane Electrode
5.11.6 Insulated Cylindrical Conductor to Plane Electrode
5.11.7 Factors Affecting Insulation Strength
5.12 Insulation between Layers
5.13 Calculation of Winding Diameter and Radial Depth
5.14 Weight of Bare Conductor, Covered Conductor and Resistance of Winding
Chapter 6 Calculation of Load Loss
6.1 Calculation of I 2R Loss
6.2 Calculation of Eddy Current Losses and Stray Losses
6.2.1 Eddy Current Loss in Winding
6.2.2 Stray Loss in Bushing plate
6.2.3 Stray Losses in Flitch Plate (Tie Plate)
6.2.4 Circulating Current Loss in Continuous Disc Winding
6.2.5 Empirical Formula for Tank Loss Calculation
6.2.6 Loss on Transformer Tank Due to High-Current Busbars
6.2.7 Empirical Formula for Calculating Total Stray Loss
6.3 Calculation of Load Loss
Chapter 7 Calculation of Reactance
7.1 Reactance Calculation of Two-Winding Transformer
7.1.1 Alternate Formula for Reactance Calculation
7.2 Reactance Calculation of Zigzag Connected two-winding Transformers
7.2.1 Effective Reactance of Zigzag Connected Transformers
7.3 Reactance Calculation with Different Ampere-Turn Distributions
7.3.1 LVβHVβLV Arrangement or Similar
7.3.2 Winding with Ducts inside or Windings Made in Two Separate Layers with Gaps
7.3.3 Reactance of Layer Winding with Reduced Layer Height towards Outer Layers
7.4 Reactance Calculations Based on Total Inductance
7.5 Reactance Calculation of Extended Winding
7.6 Zero Sequence Impedance of Zigzag Earthing Transformer
7.7 Reactance Calculation of Neutral Earthing Transformer with Auxiliary Winding
7.8 Reactance of Autotransformer with Tertiary Winding
7.9 Effective Reactance of Windings in Series (Autotransformer)
7.10 Reactance Calculation of Split Winding
7.11 Calculation of Reactance of Individual Windings
7.12 Calculation of Reactance by Finite Element Method
7.13 Zero Sequence Impedance of Three-Phase Transformers
7.14 Zero Sequence Impedance Calculation
Chapter 8 Calculation of Core Frame Size, Core Losses, Efficiency and Regulation
8.1 Core Frame Size and Core Weight Calculation
8.2 Core Loss Calculation
8.2.1 Loss Calculation Based on Average Building Factor
8.2.2 Loss Calculation by Adding of Losses Across the Grain and Along the Grain
8.3 Specific Losses of Different Grades of CRGO Materials
8.4 Core Losses of Symmetrical Core Transformers
8.4.1 Advantages of Symmetrical Wound Core
8.4.2 Manufacturing Process of Symmetrical Wound Core
8.4.3 Symmetrical Wound Core Designs
8.5 Calculation of No-Load Current (Excitation Current)
8.6 Suggested Changes of Design Parameters to Get Desired Losses
8.7 Calculation of Efficiency and Regulation
8.7.1 Calculation of Efficiency
8.7.1.1 Calculation of Efficiency as per ANSI Standard
8.7.1.2 IEC 60076 Standard and ANSI C57.12 Standard
8.7.1.3 Calculation of Efficiency as per IEC 60076 and ANSI C57.12
8.7.2 Calculation of Regulation
8.8 Calculation of Equivalent Circuit Parameters of Transformer
Chapter 9 Lightning and Switching Surges on Transformers
9.1 Introduction
9.2 Effect of Surges on Transformer Winding
9.3 Capacitive Equivalent Circuit of Transformer
9.4 Calculation of Capacitances
9.5 Calculation of Initial Voltage Distribution of a Capacitive Ladder Circuit
9.6 Impulse and Switching Surge Waves as per IEC 60076-4
9.7 Simulation of Waveform for Analytical Calculations
9.8 Design Techniques to Reduce Non-linear Impulse Voltage Distribution
9.9 Power Frequency Breakdown and Impulse Breakdown
9.10 Selection of Surge Arrester for Transformer
9.10.1 Surge Arresters Parameters
9.10.2 Calculation of Arrester Rating of Solidly Grounded three-Wire System
Chapter 10 Inrush Current in Transformers
10.1 Introduction
10.2 Problems of Transformer Inrush Current
10.2.1 Mechanical Stresses
10.2.2 Overvoltage Due to Harmonic Resonance
10.2.3 Nuisance Tripping of Transformer
10.2.4 Temporary Voltage Dip
10.2.5 Sympathetic Inrush
10.3 Calculation of Inrush Current
10.3.1 Approximate Value of the First Peak of Inrush Current
10.3.2 First Peak of Inrush Current Considering Switching Angle and Circuit Resistance
10.3.3 Estimation of Initial Few Peaks of Inrush Current
10.3.4 Calculation Example
10.4 Frequency Range of Inrush Current and Other Transients
10.5 Influence of Design on Inrush Current
10.6 Methods for Reduction of Inrush Current
10.7 Effect of System and Switching Parameters on Inrush Current
10.7.1 Source Resistance
10.7.2 Switching Angle
10.7.3 Effect of Remnant Flux on the First Cycle Peak Current
Chapter 11 Calculation of Core and Coil Assembly Dimensions, Tank Size and Tank Weight
11.1 Calculation of the Dimensions of Core and Coil Assembly (CCA)
11.2 Calculation of Dimensions of Tank
11.3 Calculation of the Size of Wooden Beam (Core Clamp)
11.4 Calculation of Weight of Tank [Radiator-Type Tank]
11.4.1 Weight of Top Cover
11.4.2 Weight of Sidewalls
11.4.3 Bottom Plate
11.4.4 Tank Curb
11.4.5 Horizontal Stiffeners
11.4.6 Vertical Stiffeners
11.4.7 Base Channel
11.5 Design of Conservator
11.5.1 Size of the Conservator
11.6 Air Cell for Conservator
11.7 Dehydrating Breathers for Transformers
11.7.1 Regeneration of Saturated Silica Gel
11.7.2 Design Parameters of Breather
11.7.3 Calculation of Quantity of Silica Gel Required
11.7.4 Self-Dehydrating Breather
11.7.5 Calculation of Desiccant in Breather Alternate Method
Chapter 12 Calculation of Winding Gradient, Heat Dissipation Area and Oil Quantity
12.1 Radiation and Convection from Surface
12.2 Heat Dissipation Data for Radiator
12.3 Calculation of Winding Gradient
12.4 Calculation of Winding Gradient: Alternate Method
12.5 Calculation of Mean Oil Temperature Rise
12.6 Calculation of Weight of Radiator Panels
12.7 Calculation of Weight of Corrugated Fins
12.8 Effect of Ambient Temperature on the Top Oil Temperature Rise
12.9 Heat Dissipation by Forced Air Cooling
12.10 Reference Ambient as per IEC
12.11 Calculation of Weighted Average Ambient Temperature
12.12 Calculation of Oil Quantity
Chapter 13 Calculation of Pressure Rise, Stresses and Strength of Tank
13.1 Calculation of Pressure Rise in Sealed Tanks
13.1.1 Tank with Pressed Steel Radiators with Air/Gas Cushion
13.1.2 Corrugated Tank with Air/Gas Cushion
13.1.3 Corrugated Tank with Complete Filling of Oil (No Air/Gas Cushion)
13.2 Calculation of Pressure and Stresses on Corrugated Fins for Completely Filled Transformer
13.3 Gas Pressure Calculation of Sealed Transformers, Considering Solubility Changes of Gas with Temperature and Pressure
13.4 Calculations of Strength of Rectangular Tank When Pressure Tested
13.4.1 Tank Dimensions and Constants
13.4.2 Calculation of Section Modulus Required for Stiffeners
13.5 Fastener Spacing and Tightening Torque of Gasket Joints of Oil-Filled Transformers
13.5.1 Introduction
13.5.2 Leakage Rate through Gasket Joint
13.5.3 Properties of Gasket Required for a Good Joint
13.5.4 Types of Gaskets Used and Comparison of Properties
13.5.5 Fastener Spacing
13.5.6 Bolt Torque
13.5.7 Joining/Splicing of the Gasket
13.5.8 Thickness of Gaskets for Distribution Transformers
Chapter 14 Calculation of the Short Circuit Forces and Strength of Transformers
14.1 Introduction
14.2 Calculation of Thermal Ability to Withstand Short Circuits
14.3 Ability to Withstand the Dynamic Effect of Short Circuits
14.4 Design Review and Evaluation
14.4.1 Comparative Evaluation with a Type-Tested Transformer of Similar Design
14.4.2 Evaluation by Check Against the Manufacturerβs Design Rules for Short Circuit Strength
Chapter 15 Rectifier Transformers
15.1 Winding Arrangements and Harmonics Produced
15.2 Calculation of the Number of Turns When Extended Star or Extended Delta Winding Is Used
15.3 Calculation of the Number of Turns of Polygon Delta Connection with Vector Group Pd0[sub(+7.5)] (7.5Β° lag)
15.4 Determination of the Phase Displacement and Ratio by Single-Phase Turns Ratio Measurement
15.5 Calculation of Ratio and Phase Angle Error
15.6 Transformers for Variable-Speed Drives (VSDs)
15.7 Effect of Winding Geometry on Load Losses
15.8 Calculation of Load Loss
15.9 Duty Cycles for Different Applications
15.10 Design Example of a Rectifier Transformer with Three Secondaries
Chapter 16 Cast Resin Transformers
16.1 Basic Design Parameters
16.1.1 Maximum Electrical Stresses
16.1.2 Insulation Design
16.1.2.1 Clearances to Enclosure and Live Parts
16.1.2.2 Clearance between Windings, Core, Etc
16.1.2.3 Clearance between Tap Links, Line Terminals to Tap Link, Etc
16.2 Calculation of Technical Parameters
16.2.1 Core Temperature Rise Calculation
16.2.2 Temperature Rise of Winding
16.2.3 Overload Capacity β For AN Cooling
16.2.4 Altitude Correction Factor
16.3 Typical Resin System for Class F applications
16.3.1 General Class F Filled System
16.3.2 Typical Resin System for Class H Applications
16.4 Enclosure for Cast Resin Transformers
16.4.1 The Air Inlet Area Required
16.4.2 Standard Clearances to Enclosure
16.5 Calculation of Time Constant of Dry-Type Transformers
16.5.1 Time Constant of Winding at Rated Load
16.5.2 Time Constant at Any Loading
16.6 Ageing and Transformer Insulation Life Expectancy
16.7 Design Using Round/Rectangular Conductor
16.7.1 Introduction
16.7.2 Conductor Insulation for Class F System
16.7.3 Layer Winding Arrangement
16.7.3.1 LV Winding
16.7.3.2 HV Winding
16.8 Calculation of Cooling Fan Capacity
16.9 Ventilation of the Transformer Room
16.10 Effect of the Enclosure IP Class on Temperature Rise
16.11 Temperature Rise of an Transformer with IP54 Enclosure
16.12 Anti-vibration Pads
16.13 RC Snubber for Cast Resin Transformers
Chapter 17 Earthing Transformers
17.1 Introduction
17.2 Basis of Rating
17.3 Rated Short-Time Neutral Current Duration and Continuous Current
17.4 Fault Current Flow through Earthing Transformers
17.5 Calculation of Zero Phase Sequence Impedance (ZPS)
17.6 Design of Earthing Transformers
17.6.1 Calculation of Maximum Permissible Current Density
17.6.2 Equivalent kVA for an Earthing Transformer
17.7 Design of an ONAN Earthing Transformer without Auxiliary Winding
17.7.1 Sample Design of an Earthing Transformer without Auxiliary Winding
17.7.2 Calculation of the Short-Time Current Density
17.7.3 Winding Design
17.8 Design of an ONAN Earthing Transformer with Auxiliary Winding
17.9 Rated Short-Time Temperature Rise
Chapter 18 Amorphous Core Transformers
18.1 Introduction
18.2 Design Procedure of Amorphous Wound Core
18.2.1 Structure of Core
18.3 Design of a Single-Phase Amorphous Core Transformer
18.3.1 Core Dimensions
18.3.2 Core Coil Assembly Dimensions and Clearances
18.4 Minimum Clearance Required for Amorphous Core Transformers
18.5 Typical Core Loss (w/kg) and Excitation Current (VA/kg) of an Amorphous Core
18.5.1 Amorphous Core Losses and VA/kg at 50 and 60 Hz (Grade 2605HB1M)
18.5.2 Amorphous Core β Losses and VA/kg at 50 and 60 Hz (Grade 2605SA1)
18.6 Calculation of Mean Length of Wound Core
18.7 Calculation of Mean Length of Windings with Wound Core
18.8 Reactance Calculation
18.9 Design Example of a 15-kVA Single-Phase Amorphous Core Transformer
18.10 Design Example of a 3-Phase Amorphous Core Transformer
Chapter 19 Design of Current-Limiting Reactors
19.1 Air-Core Dry-Type Reactors
19.1.1 Magnetic Field Produced by a Cylindrical Winding
19.1.2 Eddy Current Losses Produced by Metallic Parts
19.1.3 Clearances Required for Air-Core Reactors
19.1.4 Design Procedure of Dry Type Air Core Series Reactors
19.1.5 Sample Calculations of a Single Phase Air Core Dry Type Reactor Coil
19.1.5.1 Equalization of Current Sharing between Parallel Layers
19.1.5.2 Cooling Calculation
19.2 Oil-Filled Air-Core Reactors
19.2.1 Introduction
19.2.2 Design Procedure of Air Core Oil Filled Reactors
19.2.3 Selection of Conductor Dimensions
19.2.4 Calculation of the Dimensions of the Shield
19.3 Design of Oil-Filled Gapped-Core Reactors
Chapter 20 Scott-Connected Transformers
20.1 Basic Theory
20.2 Connection Diagram and Current Distribution
20.3 Le Blanc Connection
20.4 Application of Scott-Connected Transformers
20.5 Example of Scott-Connected Transformer Winding Design
Chapter 21 Autotransformers
21.1 Introduction
21.2 Current Distribution in the Windings of an Autotransformer
21.3 Auto Connection of 3-Phase Transformers
21.4 Tertiary Winding of an Autotransformer
21.4.1 Design Features of a Tertiary Winding
21.4.2 Eliminating the Tertiary Winding
21.5 Location of Tap Changer of Autotransformers
21.5.1 Direct Voltage Variation and Indirect Voltage Variation
21.6 Effect of Geometrical Arrangement of Tap Winding of Autotransformers
21.7 Design of a 50βMVA, 132/66-kV Autotransformer
Chapter 22 Transformers for Special Applications or Special Designs
22.1 Transformers for Use in Explosive Atmospheres [ATEX-/IECEx-Certified Transformers]
22.1.1 Introduction
22.1.2 Equipment Coding as per ATEX Marking
22.1.3 Transformer Design Consideration to comply with ATEX Certification Requirement
22.2 Furnace Transformers
22.2.1 Introduction
22.2.2 Design Features of Furnace Transformers
22.3 Multiwinding Transformers
22.3.1 Introduction
22.3.2 Three-Winding Transformers
22.3.3 Four-Winding Transformers (1 Input and 3 Output Windings)
22.3.4 Five-Winding Transformers (1 Input and 4 Output Windings)
22.4 Design of Dual-Ratio Transformers
22.4.1 Introduction
22.4.2 Design of Transformers with Dual Ratio on the Primary Side
22.4.2.1 22β11 kV Connection on the Primary
22.4.2.2 33β11 kV Series-Parallel Connection
22.4.2.3 11β6.6 kV Connection
22.5 Liquid-Filled Transformers Using High-Temperature Insulation Materials
22.5.1 Introduction
22.5.2 Thermal Class of Insulation Materials
22.5.3 Concept of High-Temperature Insulation
22.5.4 Design Parameters to be Considered
22.5.5 Thermal Class and Parameters of High-Temperature Insulation Materials
22.5.5.1 Typical Enamel Insulation for Winding Conductor
22.5.5.2 Insulation Liquids
22.6 Traction Transformers
22.6.1 Introduction
22.6.2 Design Features of On-Board Traction Transformers
22.6.2.1 Specifications and General Requirements
22.6.2.2 Harmonics
22.6.3 Design of Transformers
22.6.3.1 Core
22.6.3.2 Windings
22.6.3.3 Insulation Design
22.6.3.4 Cooling System
22.7 Symmetrical Core Transformers (Tridimensional Core)
22.7.1 Design of Symmetrical Core Transformers
22.7.1.1 Design of Transformers
Chapter 23 Transformers for Renewable Energy Applications
23.1 Introduction
23.2 Transformers for Distributed Photovoltaic Generation
23.2.1 Special Design Features Required to Meet the Service Conditions
23.3 Transformers for Wind Turbine
23.4 Emerging Trends in the Development of Transformers for Renewable Energy
Chapter 24 Condition Monitoring of Oil-Filled Transformers
24.1 Online and Off-Line Diagnostic Methods
24.2 Online Monitoring Methods
24.3 Off-Line Diagnostic Methods
24.4 Dissolved Gas Analysis
24.5 Partial Discharge MEASUREMENT
24.6 Furan Analysis and Degree of Polymerization of Transformers
24.7 Sweep Frequency Analysis
24.8 Dielectric Frequency Response Analysis
24.9 Recovery Voltage Measurement
24.10 Other Monitoring and Diagnostic Methods
24.10.1 Optical Spectroscopy
24.10.2 Search CoilβBased Online Diagnostics of Transformer Internal Faults
24.10.3 Polarization and Depolarization Current Test
24.10.4 Embedded Wireless Monitoring and Fault Diagnostic System
24.10.5 Frequency Domain Spectroscopy
24.10.6 Monitoring of Temperature
24.10.7 Load Monitoring
24.10.8 Vibration Monitoring
24.10.9 Monitoring of the Functioning of Bushings and On-Load Tap Changer
24.11 Fuzzy Information Approach for Interpretation of Results of Different Diagnostic Methods
Chapter 25 Carbon Footprint Calculation of Transformer
25.1 Introduction
25.2 Carbon Footprint Calculation Flowchart
25.3 Performance Parameters of the Transformers Considered for the Calculation
25.3.1 Raw Materials for Production
25.3.2 Transport of Raw Materials
25.3.3 Manufacture of Components and Subassemblies
25.3.4 Transport of Components and Subassemblies
25.3.5 Manufacture of the Product
25.3.6 Transportation of Product
25.3.7 Installation of Product
25.3.8 Operation (Usage) of the Product
25.3.9 Disposal and Recycling at the End of Life
25.4 Total Lifetime Carbon Footprint of 1000-kVA Transformers
Chapter 26 Seismic Response Calculation for Transformers
26.1 Introduction
26.2 Intensity and Seismic Zones
26.3 Response Spectrum
26.4 Calculation Method as per Uniform Building Code
26.5 Design of Anchor Bolt
26.6 Calculation of Natural Frequency of Vibration of Transformer
26.7 Seismic Qualifications Method as Per Clause D-3 IEEE 693
26.8 General Seismic Capability Calculation
26.8.1 Standard Amplitude Method
26.8.2 Calculated Amplitude Method
26.9 Anchor Bolt Design Considering Static, Wind and Seismic Loads
26.9.1 Static Load β D
26.9.2 Wind Load β W
26.9.3 Seismic Load β E
26.10 Seismic Qualification Testing of Transformer
26.10.1 Shake Table Testing
26.10.2 Response Spectra
26.10.3 Test Procedure
26.10.4 Acceptance Criteria and Test Report
Chapter 27 Solid-State Transformer
27.1 Introduction
27.2 Design Features of the Transformer for Smart Grid
27.3 Design of a 11kV/415V Three-Phase Solid-State Transformer
27.3.1 Basic Structure
27.3.2 Design of Module 1: (MV AC to DC)
27.3.3 Design of Module 2
27.3.4 Design of Module 3
27.3.5 Design of Module 4 (Low-Voltage Rectifier)
27.3.6 Design of Module 5 β (Low-Voltage Inverter)
27.4 Design of Medium-Frequency Transformer
27.5 Winding Design
27.5.1 Winding Arrangement
27.5.2 Calculation of Load Losses
27.5.3 Insulation Design
27.5.4 Cooling Design
27.6 Materials Required for Solid-State Transformers
27.6.1 Active Power Conversion Materials (Semiconductors)
27.6.2 Magnetic Materials
27.6.3 Conducting Materials
27.6.4 Insulation Materials and Other Parts
Chapter 28 Transformer Design Optimization
28.1 Introduction
28.2 Objective Functions for Design Optimization
28.2.1 Optimization of Lowest Initial Material Cost
28.2.2 Lowest Initial Product Cost
28.2.3 Lowest Total Owning Cost
28.2.4 Lowest Total Owning Cost Including the Cost of Lifetime CO2 Emission
28.3 Constraints of Design Optimization
28.4 Design Optimization Methods
28.4.1 Brute Force Method
28.4.2 Optimum Design of Distribution Transformers
28.4.2.1 When Upper Limits of No-Load Loss and Load Loss Are Specified
28.4.2.2 When Capitalizations of No-Load Loss and Load Loss Are Specified
28.4.2.3 Derivation of Parameters of Objective Function
28.4.2.4 Derivation of Equations
28.4.3 Genetic Algorithms
28.4.4 Harmony Search Algorithm
28.4.5 Other Optimization Techniques
28.4.5.1 Simulated Annealing
28.4.5.2 Tabu Search Algorithm
28.4.5.3 Swarm Intelligence
Chapter 29 Corrosion Protection
29.1 Typical Painting Systems for Transformer Tanks and Radiators
29.2 Design Life (Durability) of the Coating System
29.3 Painting Criterion
29.3.1 Painting of Internal Areas (Air filled)
29.3.2 Painting of Internal Oil Filled Areas
29.4 Tin Coating (Electrodeposited Coating of Tin)
29.5 Zinc Coating on Iron or Steel
Chapter 30 Calculation of Miscellaneous Technical Parameters
30.1 Overloading of Oil-Immersed Transformers
30.1.1 Introduction
30.1.2 Loss of Life of Insulation
30.1.3 Effects of Loading above the Rated Load
30.1.4 Categories of Overloading
30.1.4.1 Normal Cyclic Loading
30.1.4.2 Long-Time Emergency Loading
30.1.4.3 Short-Time Emergency Loading
30.1.5 Calculation of Hot Spot Temperature and Top Oil Temperature
30.2 Altitude Correction Factors
30.2.1 Correction Factor for Temperature Rise
30.2.2 Correction Factors for External Clearances
30.2.3 Altitude Correction Factor as Per CIGRE Report 659βJune 2016 (Transformer Thermal Modelling)
30.3 Effect of Solar Radiation on the Temperature Rise of Oil-Filled Transformers
30.3.1 Solar Radiation
30.3.2 Solar Radiation on the Surface of the Transformer
30.3.3 Calculation of the Effect of Solar Radiation on Oil Temperature Rise and Winding Temperature Rise
30.4 Circulating Current in Transformer
30.4.1 Introduction
30.4.2 Circulating Current in Tank
30.4.3 Circulating Current Across Tank Band
30.4.4 Circulating Current in Winding with Parallel Conductors
30.4.5 Circulating Current in Core Clamping Frame
30.4.6 Circulating Current from the Tank to Earth
30.4.7 Circulating Current from Core Laminations
30.4.8 Circulating Current from Geomagnetically Induced Currents
30.5 Electrical and Magnetic Fields Outside the Transformers
30.5.1 Electric Field
30.5.2 Magnetic Field
30.6 Fault Current of Transformers
30.7 Conversion of Losses, Impedance and Noise Level Measured at 50 Hz for Transformers Designed For 60 Hz and Vice Versa
30.7.1 Introduction
30.7.2 Conversion Factors for No-Load Losses and No-Load Current
30.7.3 Impedance of Transformer
30.7.4 Conversion Factors for Load Loss
30.7.5 Conversion Factor for Sound Level
30.8 IEC Rating of Transformer Designed for Operation at Higher than IEC Ambient Temperature
30.9 Heat Dissipation from Steel Prefabricated Substation
30.10 Transformer Rating for Supplying Nonsinusoidal Load
30.11 Fuses for Transformer Protection
30.12 Transformer Sound Level
30.12.1 Introduction
30.12.2 Determination of Sound Level
30.12.3 Sources of Sound from a Transformer
30.12.4 Calculation of Sound Level of Transformer
30.12.5 Design Methods to Reduce Sound Level of Transformer
30.12.5.1 Reduction of Sound Level from Core
30.12.5.2 Reduction of Sound from Winding
30.12.5.3 Other Methods for Reducing Sound Level
30.12.6 Other Factors Affecting Sound Level of Transformer
30.12.6.1 DC Bias in Magnetization
30.12.6.2 Harmonics in Load Current
30.13 Design of Connection Bus Bars inside Transformers
30.13.1 Permissible Current in a Bus Bar
30.13.2 Short-Time Thermal Capability of Bus Bar
30.13.3 Natural Frequency of Bus Bar
30.13.4 Short-Circuit Force between Bus Bars
30.13.5 Mechanical Strength of Bus Bar under Short Circuit
30.14 Calculation of Wind Load on Transformer
30.14.1 Introduction
30.14.2 Factors Affecting the Wind Load
30.14.3 Surface Roughness Coefficient
30.14.4 Topography Coefficient
30.14.5 Wind Velocity Calculation
30.14.6 Maximum Wind Load on a Surface
30.14.7 Example of Wind Load Calculation
A.1 Design of 1000 kVA, 11/0.4 kV, ONAN Transformer
A.2 Design of 20 MVA, 33/11.5 kV, ONAN Transformer
A.3 Design of 72/90 MVA, 132/34.5 kV, ONAN/ONAF Transformer
A.4 Finite Element Methods for Transformer Design
A.5 Total Owning Cost (TOC) of a Transformer
A.6 Comparison of IEC 60076 and ANSI/IEEE C.57.12 Standards
Bibliography
Index