Current-Carrying Wear Characteristics of High-Voltage GIS Plug-in Structure and Analysis on Deterioration of Electrical Contact Performance

As an electrical connection component, the contact finger has the characteristics of simple structure, small volume and suitable for batch manufacturing and it is now widely used in high-power electrical interconnection occasions, such as the contact fingers in SF₆ gas insulated switchgear (GIS), which are widely used in key components of circuit breakers, buses and disconnectors. As the key component of the plug-in structure, the contact finger bears the concentrated effect of electricity, heat and force for a long time, and its electrical current carrying capability and wear resistance are critical to the safe and stable operation of GIS equipment. In this paper, the static and dynamic wear characteristics of the contact finger, which was commonly used in GIS equipment, were studied on the self-developed electrical contact experimental platform; The influence of electrode plate surface coating, current amplitude, electrode material and other factors on the current carrying wear performance of the contact finger electrical connection structure was studied. It was found that when the normal pressure of the contact finger of the strap was higher than 10 N, the change of contact resistance was relatively stable; under the combined action of current carrying and wear, the greater the current amplitude was, the more serious the deterioration of the contact finger would be, and the contact finger would corrode with SF₆ gas; even if the current flow was within the rated range of the contact finger, when the surface of the current carrying conductor was not silver plated, the contact resistance will reach 14 milliohms in the middle of wear period due to overheating corrosion of the contact finger, which was seriously higher than the normal contact resistance. The research results of this paper can provide an important basis for the selection, structural design and fault analysis of the internal plug-in structure of GIS equipment.