Important Design Factors Influencing Reliability of Relays
01 September 1952
DESIGN FACTORS I N F L U E N C I N G R E L I A B I L I T Y O F RELAYS 977 upon them in many circuit applications, make them a subject of continuous study. In the telephone industry, for example, the completion of a single call m a y bring into play a thousand or more relays. While their principal function is to close electrical contacts, there are m a n y facets to the problem of doing this satisfactorily. Relays are produced by m a n y manufacturers in this country. When we survey their product we find t h a t there are many kinds and varieties. Shapes, sizes and configurations of relays m a y differ in accordance with the requirements of the tasks they must perform, and the environments under which they m a y work; other differences m a y be brought about by cost considerations and by design and fabrication techniques of the manufacturer. All relays, however they m a y be used, have one common objective they must be reliable. They are expected to function each time they are called upon, should do this without failure, and should continue to do so over the expected life of the equipment in which they are used. It is the purpose of this paper to discuss the more important factors t h a t are common to all relays and which have considerable influence on their reliability of performance. The design considerations discussed in this paper are presented in the following order. (1) (2) (3) (4) (5) Contact Pile-up Stability, Coil Construction, Contact "Reliability, Magnetic Stability, and Structural Stability.