Contact erosion and material transfer for contacts in automotive relays

The erosion characteristics for normally closed contacts in automotive relays was studied to understand the effects of testing temperature, testing sequencing, and methods of energizing the relay coil on contact erosion characteristics. It was found that use of electromechanical switching for energizing relay coils increases the bounce over using solid state controls with diode protection. The erosion characteristics for switching at high temperatures are much less severe in terms of pip and crater formation than erosion at 25 C or -40 C. Testing sequences starting at high temperatures and proceeding to low temperatures perform activation differences for the high versus the low temperature testing. Contact activation seems to have benefits for aiding in extending relay life for lamp load applications.