Investigation on Melt Erosion Phenomenon of Heavy-Duty Connectors under Fretting Conditions

The interconnectivity performance and reliability of electrical connectors are especially vulnerable to the mechanical vibration environment. For heavy-duty connectors, the mechanical fretting behavior together with the thermal stress caused by load current definitely result in the substantial degradation of electrical contact performance and even the disconnection of circuit. In this work, the fretting experiments of a heavy-duty connector with multiple clip contacts are carried out more than 636k seconds (equal to 176 hours) for amplitude of 200 gm and frequency of 0.5 Hz at 20 A current. The phenomenon of melt erosion and material splashing in the contact area is observed clearly after 577k seconds. Meanwhile, the transient contact voltage drop and temperature rise are recorded explicitly during the whole experiment. The variations in contact resistance, voltage fluctuation duration and fluctuation heat as a function of fretting cycles are plotted separately. Combined with the photos captured in real time, it is confirmed that the boiling and splashing of contact material could lead to the rapid change of current conduction area, which in turn, aggravates the fluctuation of contact voltage drop. Finally, the degradation process and possible failure mechanism of heavy-duty connector is presented.