This book is inspired by the Gas Insulation and Electrical Apparatus course taught at the University of Chinese Academy of Sciences (UCAS). It is structured into two main sections:Insulation Gases and Fault Diagnosis of Electrical Apparatus. The Insulation Gases section focuses on sulfur hexafluoride (SF6) and the environmentally friendly alternative C4F7N,incorporating the latest research by scientists and engineers worldwide. Key topics include insulation performance, partial discharge, decomposition characteristics, and gas-solid compatibility. The Fault Diagnosis section explores innovative condition monitoring and diagnosis technologies for high-voltage electrical apparatus, leveraging optics, acoustics, and chemistry. These advancements equip high-voltage apparatus with sensory capabilities akin to sight, hearing, smell, taste, and touch. By integrating multidisciplinary perspectives, this book examines environmental sustainability, sensing, and detection in smart grids. A standout feature is its systematic approach to practical challenges in optical spectrum analysis, quantum chemistry calculations, and molecular design/synthesis, making it especially valuable for readers seeking real-world solutions in smart grid applications.
Serving as both a graduate-level textbook and a key academic reference, this book highlights cutting-edge research and technological advances in advanced sensors and optical instruments for the power industry. It is an essential resource for researchers, engineers, and graduate students in electrical power engineering, optical/acoustic engineering, and chemical engineering.

主编张国强，中国科学院电工研究所研究员，曾荣获国家科技进步二等奖1项，省部级科技进步奖3项；发表文章150余篇，获得授权发明专利70余项，参与制定相关行业标准3项。本书副主编有韩冬博士、李康博士、邱宗甲博士、张申博士等副研究员及高级工程师，其中韩冬博士和李康博士也获得过累计4项省部级科技成果奖励。 本书编写组有两个研究方向：①在高电压与绝缘技术方面，主要从事智能电网、光谱学、分析化学及高电压技术的学科交叉研究, 新型传感器与在线监测仪器研究。②在机与电器方面，主要从事环保型绝缘介质与环保型输变电设备研究，高频高压变压器和电抗器研究等。 近5年本教材编写组承担的科研项目主要有以下7项：①国家科技部重点研发计划智能电网技术与装备重点专项环保型管道输电关键技术。②国家科技部重点研发计划智能电网技术与装备重点专项功率电力电子装备用中高频磁性元件关键技术。③国家电网公司总部重点科研项目高精度光声光谱仪研制及应用示范。④中国科学院科研仪器设备研制项目基于发射光谱的电气设备绝缘状态检测系统。⑤国家科技部重点研发计划储能与智能电网技术重点专项新型环保绝缘气体研发与应用。⑥北京市科委项目新型环保绝缘气体开关样机研制与产业化。⑦国家科技部基础科研条件与重科研仪器研制与开发重点专项光学麦克风。 本书编写组成员参与编写的著作有：《中国战略性新兴产业研究与发展智能电网》《电力变压器手册》《中国电机工程学会专题报告2021》上卷的《GIS设备状态检测技术及应用》《电力受端系统的动态特性及安全性评价》等。

Table of Contents
Preface
1 Introduction 1
1.1 Overview of Electrical Equipment 1
1.1.1 Primary Equipment 1
1.1.2 Secondary Equipment 3
1.2 Insulation Design Requirements 4
1.2.1 Electrical Requirements 4
1.2.2 Physical Limitations 5
1.2.3 Working Environment 5
1.2.4 Mechanical Requirements 5
1.2.5 Thermal Conditions 6
1.2.6 Processing 6
1.2.7 Reliability 7
1.3 Insulation Failures of Electrical Equipment 8
1.3.1 Insulation Failures and Their Hazards 8
1.3.2 Characterization of Insulation Condition 9
1.4 Advanced Sensors and Measurement Instruments in Electric Power Industry 13
1.4.1 Electrical and Magnetic Sensors 14
1.4.2 Optical, Chemical, Acoustic, and Mechanical Detection 15
1.5 Online Monitoring and Condition-Based Maintenance 21
1.5.1 The Main Problems with Offline Monitoring 22
1.5.2 Online Monitoring 23
1.6 Technical Requirements for Online Monitoring Systems 26
Bibliography 27
2 SF6 Gas and Its Environmental-Friendly Alternatives 28
2.1 Review of Insulating Materials 28
2.1.1 Gases 28
2.1.2 Vacumn 29
2.1.3 Liquids 29
2.1.4 Solids 31
2.2 SF6 and Its Alternatives 36
2.2.1 SF6 36
2.2.2 Situation and Development of Environmentally Friendly Insulating Gas 40
Table of Contents
2.3 Insulating and Extinguishing Performance of C4F7N 41
2.3.1 Power Frequency and DC Breakdown Characteristics 41
2.3.2 Lighting Impulse and Surface Flashover Characteristics 42
2.3.3 Arc Extinguishing Characteristics 43
2.4 Decomposition Characteristics of C4F7N 44
2.4.1 Introduction of Quantum Chemistry Theory 45
2.4.2 Decomposition and By-product Formation Mechanism 46
2.4.3 Decomposition By-product Measurement for C4F7N 58
2.4.4 Fault Decomposition Characteristics of SF6 and C4F7N/CO2 67
2.4.5 Fault Criteria of C4F7N/CO2 Decomposition 83
2.5 Compatibility Characteristics of C4F7N and Solid Materials 91
2.5.1 Solid Absorbent Materials 91
2.5.2 Rubber Sealing Materials 98
2.5.3 Epoxy Resin Materials 118
2.6 Review Questions 124
Bibliography 124
3 Atomic Emission Spectrometry 127
3.1 Introduction 127
3.2 Basic Principles 127
3.2.1 Atomic Emission Spectroscopy 128
3.2.2 Laser-induced breakdown spectroscopy (LIBS) 129
3.2.3 The Physics and Chemistry of the Laser Plasma 130
3.3 Forming the LIBS Plasma in Gases, Liquids, and on Solids 133
3.3.1 Gases 133
3.3.2 Liquids 134
3.3.3 Particles 134
3.3.4 Solids 134
3.4 Components for a LIBS Apparatus 136
3.4.1 General 136
3.4.2 Laser Systems 137
3.4.3 Methods of Spectral Resolution 138
3.4.4 Detectors 139
3.5 Industrial Application of LIBS 140
3.5.1 LIBS Detection in Electric Power Grids 140
3.5.2 LIBS Application in Thermal Power Plants 149
3.5.3 LIBS Application in Nuclear Power Stations 154
3.5.4 LIBS Application in Metal Alloys Industries 155
3.6 The Lowest Detectable Limit of LIBS 159
3.6.1 LIBS Lowest Detectable Limit 159
3.6.2 LIBS Typical Suppliers 159
3.7 Review Questions 161
Bibliography 161
4 Gas Chromatography & Photoacoustic Spectroscopy 163
4.1 Introduction 163
4.2 Insulating Liquids 164
4.3 Decomposing and Relevant Chemical By-products 165
4.4 Importance of Oil Sample Analysis 168
4.5 Oil Sampling Guidelines and Industry Practices 170
4.6 Interpretation Techniques 171
4.6.1 Fault Types 172
4.6.2 Techniques that Rely on the Gas Concentrations and Ratios 173
4.7 Online Dissolved Gas Analysis by Sensors and Chromatography 177
4.7.1 Online Monitoring of Power Transformers 178
4.7.2 Online Monitoring of Bushings and Lightning Arrestors 183
4.8 Online Dissolved Gas Analysis by Photoacoustic Spectroscopy 186
4.8.1 Introduction 186
4.8.2 Fundamentals of Photoacoustics 186
4.8.3 Photoacoustic Sensing Applications in Smart Grids 195
4.9 Typical Instrument Suppliers and the Measurable Scope of PAS 197
4.9.1 PAS Typical Suppliers 197
4.9.2 The Measurable Scope of PAS 199
4.10 Review Questions 201
Bibliography 201
5 Tunable Diode Laser Absorption Spectroscopy 203
5.1 Introduction 203
5.2 Basic Principles 203
5.2.1 Laser Spectroscopy Theory 205
5.2.2 Molecular Absorption Spectroscopy 207
5.2.3 Beer-Lamberts Law 208
5.2.4 Spectroscopic Databases 209
5.2.5 Unique Advantages of TDLAS 209
5.3 Main Components of TDLAS and Relevant Techniques 211
5.3.1 Laser Sources of TDLAS 211
5.3.2 Laser Systems Signal Processing Techniques 212
5.4 Cavity Enhancement Techniques 214
5.4.1 Multipass Spectroscopic Absorption Cells 215
5.4.2 Cavity Ring-down Spectroscopy (CRDS) 217
5.5 Electric Power Industries Applications of TDLAS 218
5.5.1 Introduction 218
5.5.2 TDLAS Applications in Dissolved Gas Analysis 219
5.5.3 CRDS Applications in GIS Faults Detection 222
5.5.4 TDLAS Applications in SF6 Gas Leak Detection 226
5.5.5 TDLAS Applications in Coal-fired Power Plants 227
5.6 Review Questions 229
Bibliography 229
6 Infrared Thermal Imaging and Gases Leaking Detection 231
6.1 Introduction 231
6.2 Key Factors and Characteristics of Thermal Imaging 233
6.3 Main Components of Infrared Thermographers 235
6.4 Multispectral vs Hyperspectral Imaging: Differences 238
6.5 Smart Grid Applications of Infrared Thermal Imagers 240
6.6 Remote Gas Leak Detection by IR Imager 247
6.6.1 Infrared SF6 Gas Leak Imager in Electric Power Grids 247
6.6.2 Arbitrary Gas Leak Detection by Commercial IR Cameras 250
6.7 Hyperspectral Imaging Applications in Electric Industry 253
6.8 Review Questions 255
Bibliography 255
7 Ultraviolet Spectroscopy & UV Camera 257
7.1 Introduction 257
7.2 Basic Principles 258
7.2.1 The Origin of UV Band Structure 258
7.2.2 The Origin of Electric Discharge and Solar Blind Bands 259
7.3 Main Components of UV Cameras 263
7.3.1 UV Filters 263
7.3.2 UV Lens 264
7.3.3 Photomultiplier Tubes 264
7.3.4 Comparison among CCD,EMCCD,ICCD 267
7.4 Application Examples of UV Cameras in Smart Grids 269
7.5 Comparison of Ultraviolet and Infrared Imaging 273
7.6 Review Questions 274
Bibliography 275
8 Electrochemical Gas Sensors for GIS Off-line Detection 276
8.1 Introduction 276
8.2 Basic Principles 276
8.2.1 Properties of Sulphur Hexafluoride SF6 Gas 279
8.2.2 Electrical Characteristics of SF6 Gas 282
8.3 Decomposition of SF6 and Its Mixtures in Gas Insulated Equipment 282
8.4 Electrochemical Sensors for GIS 284
8.4.1 Fundamentals of Electrochemistry for SO2 & H2S Sensors 285
8.4.2 Market for Electrochemical Gas Sensors 287
8.5 Application Examples of Electrochemical Sensors for GIS 288
8.6 Review Questions 291
Bibliography 291
9 Chemiluminescence and UV Absorption Detection 293
9.1 Introduction 293
9.2 Basic Principles 294
9.2.1 Theoretical Foundation of Partial Discharge Phenomenon 294
9.2.2 Chemical Reactions of Air under Corona Discharge 298
9.3 Components of Ozone and NOx Monitors 304
9.3.1 UV Absorption Spectrum for Ozone Monitoring 304
9.3.2 Chemiluminescence Sensors for NOx Measurement 311
9.4 Application Examples of Air Decomposition Analysis 313
9.4.1 The Relationship between Ozone and Partial Discharge 313
9.4.2 Ozone Distribution in Hydro-generators 323
9.4.3 Ozone Sensors in an Medium Voltage Switchboard 327
9.4.4 Forthcoming Applications of Ozone Sensors 331
9.5 Fundamental Study of Emission Spectrum in GIS 333
9.5.1 Experimental Model of Emission Spectra Analysis in SF6 333
9.5.2 Emission Spectra of Corona Discharge in SF6 334
9.5.3 Emission Spectra of Spark Discharge in SF6 336
9.5.4 Emission Spectra of Surface Discharge in SF6 337
9.6 Review Questions 339
Bibliography 339
10 Electro-optic and Magneto-optic Sensors 341
10.1 Introduction 341
10.2 Basic Principles 342
10.2.1 Kerr Electro-optic Effect 342
10.2.2 Pockels Electro-optic Effect 343
10.2.3 Faraday Magneto-optical Effect 345
10.3 Applications of Electro-optic and Magneto-optic Sensors 347
10.3.1 Current and Voltage Combo Sensors for Substations 347
10.3.2 Research and Development of ±800 kV UHVDC Fiber Optical
Current Transducer 351
10.4 Review Questions 352
Bibliography 353
11 Michelson and Fabry-Perot Interferometer 355
11.1 Introduction 355
11.2 Basic Principles 355
11.2.1 Category of Interferometers 355
11.2.2 Working Principle of Michelson Interferometer 357
11.2.3 Working Principle of Fabry-Perot Interferometer 359
11.3 Applications of Michelson and Fabry-Perot Interferometers 362
11.3.1 Trace Gas Detection by Michelson Interferometers 362
11.3.2 Partial Discharge Detection by Michelson Interferometers 364
11.3.3 Partial Discharge Detection by Fabry-Perot Interferometer 367
11.3.4 Temperature Sensing by Fabry-Perot Interferometers 369
11.3.5 Mechanical Vibration Sensing by Fabry-Perot Interferometers 370
11.3.6 Acoustic Wave Sensing by Fabry-Perot Interferometers 370
11.3.7 Ultrasound Sensing by Fabry-Perot Interferometers 370
11.3.8 Pressure Sensing by Fabry-Perot Interferometers 371
11.4 Review Questions 371
Bibliography 372
12 Acoustic and Ultrasonic Imaging 374
12.1 Introduction 374
12.2 Basic Principles 374
12.2.1 Audio Spectrum 374
12.2.2 Working Principle of Microphones 378
12.2.3 Piezoelectric Effect and Piezoelectric Materials 388
12.3 Applications of Acoustic and Ultrasonic Sensors 390
12.3.1 Causes of Noise in Power Transformers 393
12.3.2 Voiceprints and Their Recognition 395
12.3.3 Acoustic Imaging of Mechanical Vibration and Noise 396
12.3.4 Partial Discharge Ultrasonic Detection in Enclosed Spaces 401
12.3.5 Ultrasonic Camera Applications in Substations 406
12.4 Review Questions 409
Bibliography 409