Electrical Contacts

Abstract

Many different forms of electrical contact are employed in engineering, but in the present book we are concerned mainly with contacts for switching relatively small power loads. They have to satisfy a variety of requirements, all of which can be summed up in one word, reliability. The reliability of a contact is governed largely by the material it is made of and the load it has to carry, but also to some extent by the design of the system in which it operates, which includes the contact itself, the wipers, springs, method of actuation and the climate. A contact reaches the end of its useful life when it no longer has the desired reliability. Although the life can be extended by repair or replacement, one of the principal demands nowadays is that contacts should continue to function faultlessly for very long periods without maintenance.