Rezensionen
Rezensionen
P.C.T. van der Laan
Electromagnetic Fields in Electrical Engineering
Understanding Basic Concepts
Rezension
The subtitle of this little book is "Understanding basic concepts". Piet van der Laan has only recently retired from the Technical University of Eindhoven where he was professor of Electrical Engineering, with an emphasis on high voltage power engineering and, consequently, an unavoidable interest in EMC. This book tackles the basics of electromagnetic field theory, from the perspective that "too much mathematics in field theory has - unfortunately - convinced many people that circuit theory is more practical and relevant."
Van der Laan does not denigrate circuit theory; by contrasting Maxwell and Kirchhoff, he merely shows that it is in fact derived from the more universal field theory. The mathematics is not absent, but neither is it overwhelming, and it is clearly and profusely illustrated with many diagrams. The various aspects of electromagnetic fields are concisely covered and put into context with what electrical and electronic engineers are more familiar with - components, wires, motors and structures. He is not above a little whimsy; having calculated as an example the capacitance of the Earth as 708µF, he says "notice how inconveniently large a Farad is; even our Sun with a radius of 696000 km has only a capacitance of 77.4 mF". As an aid to understanding the physical basis of, well, the whole of electrical and electronic engineering, this book is invaluable.
P.C.T. van der Laan
Electromagnetic Fields in Electrical Engineering
Understanding Basic Concepts
Rezension
This is an excellent book. Each page is arresting. The sub-title and “naïve-art” sketches underscore the value of Piet van der Laan’s approach – clarity, but with profound insight. As I read through the text, I was reminded of the superficially elementary but deeply philosophical book, “Le Petit Prince” by Antoine de Saint-Exupéry. Both books present illustrated accounts of subjects that capture important principles, the most valuable of which is to look beyond. As a physicist, van der Laan, delves into the underlying principles.
The dilemma facing engineering educators in electromagnetics is highlighted in the first paragraphs of the book’s preface. EM fields are fundamental to electrical engineering and are inextricably linked to currents and voltages, which cannot be properly appreciated without understanding the fields. As an educator myself, I immediately admired the framing of the discipline evident at the beginning of the book. Van der Laan confesses at the end that electric and magnetic fields are “invented” quantities that are an essential means to understand electromagnetic (EM) phenomena.
The two stated primary objectives are to refresh practicing engineers who have lost currency in the subject and to introduce newcomers to EM fields. By the end of the book, I would describe these intentions as having been more than fully met. The preface in itself is an education and led me to much reflection on the way in which I would like to teach the subject material. Piet van der Laan adds humour to the book through some illustrations and light-hearted descriptions involving bookkeepers, butterfly nets and skiers. None of this should lull the reader into a false sense of security – the topics demand attention at all levels.
Chapter one introduces the scene broadly. The abstraction of circuit from EM theory is quickly presented as an important consideration. We make ground using circuit theory models, but if the link to underlying EM principles is lost, errors can be made. This is particularly true in the fields of EM interference and compatibility (EMI and EMC), subjects which conclude the book. The possibility of using an historical development of electricity and magnetism is raised briefly and then set aside. The purpose of the book, states van der Laan, is to clarify why electric and magnetic fields are as essential to modern electrical engineering as currents and voltages. From the start, we gain a good picture of wave, energy and power transmission through both guided and non-guided media. EM force is attributed to E and B-fields and simple statements concerning subjects such as radiation are given. The metaphorical illustrations achieve their purpose well.
Chapter two on fields and fluxes begins with the origins of electric and magnetic fields. The material will cause most people to ponder – a powerful educational technique. Readers will be elegantly introduced to, or reminded of, line and surface integrals and the practical implications of charges, fields and fluxes. The connection of field to circuit theory and the measurement of circuit properties are covered succinctly. This provides a platform to explain good and bad measurement practice.
The strong early chapters pave the way for the presentation of Maxwell’s laws in integral form (Chapter 3), Forces, Torque, Motors and Energy (Chapter 4), and then the very important description of the Maxwell and Kirchhoff models in Chapter 5. This is a significant chapter and relies upon the methodical developments of the previous work. A studious reader will be encouraged by what transpires in this chapter as a sense of understanding is achieved. The “ah ha” experience continues with a foray into capacitance and inductance in Chapter 6 and mutual inductance and coupled coils in Chapter 7. The oft described “black art” of EMC is exposed in Chapter 8 and, as if by magic, seems to be an entirely tangible subject as presented by Professor van der Laan.
The supporting appendices and summaries at the end of chapters sustain the quality of this work. I have greatly enjoyed this book and would whole-heartedly recommend it as a thorough success in achieving its own two objectives indicated at the outset.
