The majority of low cost relay controlled power equipment, ie. consumer products incorporating power controls, are designed with relays that are rated for the statistical and worst case arcing loads that can be anticipated when switching typical AC loads such as heating elements and motors. The basis for this is that the arcing during switching is the primary destructive force that limits the life of the relay contacts. Although there are other aging mechanisms involved in relays, this invention is primarily concerned with reduction in aging effects due to relay arcing.
In these cases where the contact arcing is the primary aging mechanism, the life of the relay is inversely proportional to the amount of arcing incurred during operation. The typical approach to solving this problem has been that if the relay can't handle the arcing and meet the reliability requirements for the product, get a bigger relay.
This approach has been used on most if not all consumer products and most industrial products, however, at the industrial and/or military level, where cost is not necessarily a limiting factor, other approaches have been used such as special magnetic blow-out coils to quench arcing.
USPTO Backgrounds
USPTO Backgrounds