Preface to the First Edition

I began my studies in the fascinating world of electrical contacts as a graduate student at the University of Wales in the mid-1960s. Since that time, I have been involved with electrical contacts both as a research scientist and as a developer of switching components. Even though the subject is as old as electricity, it has continued to evolve. To those of us who have continued working in this field, it has provided a stimulating and ever-expanding subject for research. It has, however, always been—and still is—on the periphery of other major technology achievements. For example, plug-in connectors are a vital, but ignored, component of an integrated circuit—ignored, that is, until the connector fails. Another example that comes to mind is the development of sliding contacts that work in a space environment, which have been essential for the successful development of the communication satellite. Experts in electrical contact technology can cite many such examples. In fact, electrical contacts of one type or another are found in every electrical component, and the proper operation of the contacts is always vital to the reliable operation of that component.

The subject of electrical contacts is by necessity multidisciplinary. No matter which academic career you initially begin with, as soon as you start working in this area, you soon develop a good general knowledge of many others. The study of electrical contacts requires knowledge of physics, chemistry, mechanical engineering, electrical engineering, materials science, and environmental science. It also requires a broad applications knowledge; contacts can be found in electronic circuits that may carry currents of less than 10⁻⁶ A and also in power circuits that may carry currents of greater than 10⁶ A.

The aim of this book is to provide information on the current state of electrical contact science and engineering to practicing scientists and engineers, as well as to provide a comprehensive introduction to the subject for technology graduate students. To do this we use the knowledge and experience of 17 contributors who are actively involved in the research, development, manufacture, and application of electrical contacts. Nine of these contributors have received the Ragnar Holm Scientific Achievement Award for their contributions to the science of electrical contacts, which is given by the IEEE Holm Conference on Electrical Contacts. The contributors reflect the great diversity that characterizes electrical contact applications.

This type of book is long overdue. The latest books published on this subject in English have been long out of print. Many times it would have been extremely helpful to have had readily available, in one source book, a thorough, up-to-date overview of the subject, application information, pitfalls to avoid, and design tips. There has also been a need for application guidance that is independent of that given by commercial contact manufacturers. This book provides a practical approach to the subject and gives the reader insights into electrical contact application that have been derived from the contributors’ extensive experience. For those readers who would like to investigate a particular aspect of the subject in more detail, each chapter includes an extensive list of references where such information can be found.

The book is divided into six parts. Part I has three chapters that introduce the contact interface and the subject of contact tarnishing and corrosion. In Part II, static contacts are presented. The four chapters in this part discuss materials, design, and applications covering the range from electronic connectors to high-power electrical utility connectors. The five chapters in Part III develop the subject of arcing contacts. The part begins with a discussion of the electric arc and continues with a review of practical design considerations for switching devices that interrupt currents in the range 0.1 to 100,000 A. Part IV continues the discussion of arcing contacts, covering the choice of contact materials, their attachment, testing, and contamination effects. Part V deals entirely with sliding contacts. Its four chapters describe the fundamentals of sliding contacts and their application over a wide range of currents and conditions. Finally, in Part VI tables of useful data are provided.

I wish to extend a personal note of thanks to all the contributors. The inclusion of their chapters, which distill the knowledge amassed from their years of research and experience, has made this book the comprehensive and definitive volume that we originally envisioned. Special mention is due to Erle Shobert, Gerry Witter, Guenther Horn, and Tony Lee, who were on the initial committee that began this project. I would especially like to thank Gerry Witter, who developed Part Four. I also wish to acknowledge the valuable help that I have received from Mort Antler and Werner Rieder. They have always been prepared to read manuscripts, offer positive and constructive criticism, and make helpful suggestions as the book progressed.

Paul G. Slade, 1999