Failure Analysis of Power Relays With Multiple Breaks in the Electrical Endurance Experiments

Multiple breaks are favorable for arc extinguishment of relays switching heavy load. However, the existed asynchronous mechanical separation of contact pairs and associated unbalanced arcing behavior limit the electrical lifetime to some extent. In this article, the typical contact voltage and contact current waveforms of double breaks within power relays are presented. Based on the variations in bounce energy, contact resistance, and arc energy as a function of switching cycles, the effect of contact gap on the electrical lifetime of power relays is analyzed explicitly. Furthermore, the failure process of power relays with two bridges is characterized by the recorded breaking time difference of bridges. The observed significant asynchronous breaking phenomena in the end of electrical lifetime experiments attribute to the contact welding failure of power relays.