Optimization of the performance of copper/graphite system for GIL Tri‐post grounding electrode based on plasma sintering technology

Abstract

Grounding electrodes, as crucial components of GIL bushings, experience friction with the GIL shell during long-term operation, generating metal particles that induce partial discharge. This phenomenon can lead to internal insulation breakdown, severely compromising GIL operation. This study focuses on enhancing the wear resistance of grounding electrodes by proposing a solution involving copper-graphite composites. Copper/graphite composite materials were fabricated using Spark Plasma Sintering technology. Additionally, the impact of graphite content and particle size on wear resistance, hardness, and electrical conductivity was comprehensively analyzed. Performance evaluation using radar chart analysis identified the optimal solution. The results indicate that at a sintering temperature of 960 °C, pressure of 45 MPa, and holding time of 15 min, with a graphite mass fraction of 7 %, the grounding electrode material exhibits a smooth surface and uniform distribution of graphite. Furthermore, when the graphite particle size is 4 μm, the friction coefficient remains approximately 0.7 with minimal fluctuations. The abrasion produces scratches measuring only 190 μm, and the wear rate is recorded at 2.1128 × 10−4 mm³/N·m, while the hardness reaches 59.6 HV, an increase of 19.6 HV compared to a particle size of 40 μm. In conclusion, an appropriate graphite content effectively enhances the wear resistance of the grounding electrode, and a reduction in graphite particle size optimizes overall performance. When the composite material contains 7 % graphite with a particle size of 4 μm, the performance is optimal, allowing the grounding electrode to maintain its original properties while demonstrating excellent wear resistance. This study provides a significant approach to optimizing the performance of grounding electrodes.