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2018 | Book

High Voltage Engineering

Fundamentals - Technology - Applications

Author: Andreas Küchler

Publisher: Springer Berlin Heidelberg

Book Series : VDI-Buch


About this book

This book is based on the leading German reference book on high voltage engineering. It includes innovative insulation concepts, new physical knowledge and new insulating materials, emerging techniques for testing, measuring and diagnosis, as well as new fields of application, such as high voltage direct current (HVDC) transmission. It provides an excellent access to high voltage engineering – for engineers, experts and scientists, as well as for students.

High voltage engineering is not only a key technology for a safe, economic and sustainable electricity supply, which has become one of the most important challenges for modern society. Furthermore, a broad spectrum of industrial applications of high voltage technologies is used in most of the innovative fields of engineering and science.

The book comprehensively covers the contents ranging from electrical field stresses and dielectric strengths through dielectrics, materials and technologies to typical insulation systems for AC, DC and impulse stresses.

Thereby, the book provides a unique and successful combination of scientific foundations, modern technologies and practical applications, and it is clearly illustrated by many figures, examples and exercises. Therefore, it is an essential tool both for teaching at universities and for the users of high voltage technologies.

Table of Contents

Chapter 1. Introduction
The task of high voltage engineering is to keep high electric field strengths under control. First, as an introduction, the fundamental challenge is explained, i.e. that the electric stresses in an insulating system must always stay lower than the dielectric strength. Then, the application areas and the perspectives of high voltage engineering in electrical power engineering and in other fields of engineering are described. The topics of the book are briefly addressed and they are illustrated with the example of a bushing, in order to give a first impression of the way of thinking in high voltage engineering.
Andreas Küchler
Chapter 2. Electric Stresses
The determination of electric field strengths is of fundamental importance for quantification and control of high voltage stresses. First, the theoretical equations describing electrical fields are summarized. The following sections describe that different technical stresses due to high DC, AC and impulse voltages result in the formation of different types of fields. For simple configurations, steady-state and quasi-stationary (slowly varying) fields can be calculated or estimated by analytical methods. Here, simple insulation systems with a single homogeneous dielectric and insulation systems made of different layered dielectrics are distinguished. There are fundamental differences for quasi-stationary fields at AC and impulse voltages and for the steady-state DC case. So-called field grading methods can be used for reducing electrical stresses. Complex insulation systems, which cannot be approximated by simple geometries and cannot be evaluated analytically, require numerical calculation. Fast changing electromagnetic phenomena, such as traveling waves on lines, need special consideration.
Andreas Küchler
Chapter 3. Electric Strength
The dielectric strength of insulating media must be higher than the electric stress under all possible conditions. Unfortunately, dielectric strength is often subject to significant statistical variations. Therefore, the fundamentals of statistics are considered at first. If the electrical strength is insufficient, discharges occur. They are treated separately depending on the type of insulating medium: Gas discharges can be well described in terms of physics, occur at comparatively low field strengths and show very different manifestations in uniform and non-uniform fields, on surfaces, in cavities or in the atmosphere. In other media, much higher dielectric strengths are often possible, but they depend on a large number of parameters. Special attention is paid to discharge processes in liquids, solids and vacuum. So-called partial discharges that do not lead directly to breakdown are especially important for the erosive ageing of insulating materials and for the diagnosis of insulation systems under applied voltage.
Andreas Küchler
Chapter 4. Dielectric System Characteristics
The dielectric system properties of insulating materials, which manifest themselves in properties such as permittivity, dissipation factor, conductivity or polarization behavior, have strong influences on the formation of electric fields in insulation systems. Starting point of the considerations is the description of fundamental polarization behavior of dielectrics in the time domain and in the frequency domain. Quantities that are deduced from that are permittivity, dissipation factor and complex permittivity, which are relevant for AC fields. Also, conductivity and polarization behavior being relevant for DC fields and transient fields can be deduced. Normally, these properties depend on parameters such as temperature, field stress, frequency or water content, and they are significantly different for gases, liquids and solids. For a description of dielectric properties in accordance with system theory, the classic parallel and series equivalent circuits, polarization current curves, permittivity and dissipation factor spectra, linear and non-linear material equivalent circuits as well as multi-physics approaches are used. Inhomogeneous dielectrics must be described by spatial discretization.
Andreas Küchler
Chapter 5. Insulating Materials
Electrical insulation materials cannot be applied only on the basis of their dielectric strength. For practical application, the whole characteristic profile including electrical, mechanical, thermal, physical and chemical properties is relevant because materials in electrical systems and equipment also always fulfil the non-electric functions as “construction materials”. For this, basic information is given for selected important insulating materials, such as the significance in high voltage engineering applications, the basic material structure, special dielectric properties, other special properties, the manufacturing and processing technology as well as the performance in operation. The classification of material groups follows specific high voltage engineering features: Gases (air, SF6, alternative gases), inorganic solid insulating materials(ceramics, porcelain, glass, mica), thermoplastic insulating materials (polyethylene, PVC), thermosetting plastics and elastomers (epoxy resin, polyurethane, silicone elastomers), nano-composites, insulating liquids (mineral oil, synthetic liquids, vegetable-based liquids) as well as impregnated fibrous materials(paper, pressboard, synthetic materials).
Andreas Küchler
Chapter 6. Testing, Measuring and Diagnosis
High-voltage test and measuring techniques and technologies for diagnostics and monitoring of high voltage insulating systems are essential for the proof of operational safety of equipment and systems prior to commissioning and during service operation, because small defects can develop into serious consequences. The starting point of the considerations is the system of quality assurance and insulation coordination, for which the voltage stresses in the net, the protection elements and the dielectric strengths of the insulation or test voltage levels are coordinated. The generation of high test voltages is performed by special equipment for AC, DC and impulse voltages that can often be cascaded. The measurement of high voltages is normally based on special voltage dividers, but alternative systems (measurement spark gaps, field sensors, instrument transformers) are also used. Additionally, the technologies for current measurement and for undisturbed measurements (EMV) must be considered. During a voltage test and during service operation, electrical, dielectric, chemical and physical methods are used for diagnostic purposes, in order to assess the condition of equipment.
Andreas Küchler
Chapter 7. Applications
The applications of high voltage insulating systems are realized in different forms due to the type of equipment and due to the type of voltage stress. The configuration of insulation systems is performed by means of the principles and tools that are described in the previous chapters. Typical insulation systems for AC voltages are considered for cables, accessories, bushings, transformers, capacitors, circuit-breakers and electrical machines. Insulation systems for DC voltages must first of all be discussed with respect to specific electrical stresses, dielectric strength and specific design features. Then the consideration of typical DC insulation systems is focused on capacitors, transformers, bushings, cables and accessories for HVDC applications and on power electronic systems. Typical insulation systems for impulse voltages are also discussed with regard to stresses and strengths at first. Then applications for energy storage capacitors, impulse capacitors and transformer barrier systems are described. Other application examples are presented for lightning protection, pulsed power technology, light and laser technology, X-ray technology, particle precipitation and spark plug insulation. An own section is dedicated to superconductive equipment.
Andreas Küchler
High Voltage Engineering
Andreas Küchler
Copyright Year
Springer Berlin Heidelberg
Electronic ISBN
Print ISBN