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More than 170 Years of Innovation

Sir Charles Wheatstone invented the first electromechanical relay in 1834 to amplify electrical signals, making information transmission over long distances possible for the first time.

Relay functionality diversified over time, and at the beginning of the 20th century the first telephone sy?tems were built based on electromechanical switching.

With the appearance of semiconductors in the 1960s, it was said that relays would be dead within a few years. In reality, the exact opposite happened. While the design of relays had not changed significantly for more than 100 years, important innovations were introduced into relay design. Instead of replacing electromechanical relays, semiconductors expanded their applications.

Combining semiconductors with electromechanical relays allowed electronics, telecommunication systems and test equipment to be developed at a cost that made them accessible to a mass market. That progress is evident today in the automotive industry, where up to 150 relays are used per car. Relays can now be found in all kinds of industries, including telecommunications, industrial control, medical equipment, household appliances, automotive and aerospace, to name a few.

The current state-of-the-art in relays and switches is represented in this 6th edition of the Engineers Relay Handbook, which has been completely revised and rewritten from previous versions. This book follows the tradition of the previous five editions, presenting current knowledge of relay technology and designs in a concise, but comprehensive way.

The new edition covers both electromechanical and semiconductor-based relays, providing the basics on subjects such as contact physics, the design of magnetic circuits, and how semiconductors function. Chapters within the book present information on the different types of relays, their applications and relevant standards. This book addresses both designers and users of relays, with an emphasis on helping young engineers design or use relays in the best way possible. The many references documented in the 18 chapters provide an entry point for more detailed information available on relays and their limitless applications.

The newest Engineers Relay Handbook would not be possible without the dedication of our contributors, whose work represents knowledge accumulated during years of research, development and personal experience -we thank you all. A special thanks also goes to the companies supporting the International Relay and Switch Technology Conference (IRSTC) that serves as the setting for the launch of this new edition.

Finally, we acknowledge two people who made special efforts to get this book published, and who have had a significant impact on the development of the relay industry: Don Dangott, who was Executive President of NARM for nearly 10 years, and Dr. Werner Rieder, who wrote the first chapter, "Contact Basics." Both passed away while work on this book was in progress.

We hope everyone in the field will benefit from the newest edition of the Engineers Relay Handbook, and use it to further drive the innovation that has made relays and switches a central part of our lives for more than 170 years.


Organization: Electronic Components Industry Association
Document Number: ecia engineers relay hb
Publish Date: 2006-01-01
Page Count: 514
Available Languages: EN
DOD Adopted: NO
ANSI Approved: NO
Most Recent Revision: YES
Current Version: YES
Status: Active