Impact of Mechanical Parameters on Switching Results of Electro-Mechanical Contactors

The studies focus on early failures in electro-mechanical switching device endurance tests, such as contactor AC3 and AC4 lifetime test. Endurance tests in commercial contactors with different contact springs, providing variations in contact normal load, were performed with focus on possible influences on make/break characteristics and temperature rise. Furthermore, the impact of aged contact springs and therefore relaxation effects with several types of contact springs were studied. Another part focused on the impact of closing momentum on contact bouncing by application of different driving coils (AC vs. DC drives) and thus in relation to electrical lifetime. In conclusion all tests show the importance of mechanical boundary conditions to contactor endurance, and their significance as basis for proper contact material benchmarking.