Modeling and Analysis of Electrothermal Contact Characteristics for High-Voltage Switch Contacts Considering the Influence of Coatings and Conductive Grease
Mo Di1, Guan Xiangyu2, Li Jiancheng1, Shu Shengwen1
1. School of Electrical Engineering and Automation Fuzhou University Fuzhou 350108 China; 2. Fujian Key Laboratory of New Energy Generation and Power Conversion School of Electrical Engineering and Automation Fuzhou University Fuzhou 350108 China
Abstract：High-voltage switchgear is a critical component in AC-DC transmission projects, and its reliable operation is essential for the safety and stability of the entire power network. Similar to other machined surfaces, the contact surfaces of high-voltage switch contacts are rough and uneven. To maintain low, stable contact resistance and high current-carrying capacity, these surfaces are coated with highly conductive layers and covered with conductive grease（CG). In studies involving finite element modeling for fault mechanism and characteristic analysis, equivalent simplifications of contact points are often employed to reduce computational resources and time. The coatings and CG on the contact surfaces introduce new conductive and heat-transfer paths at the interface, leading to deviations between the actual electrical/thermal contact resistance and the calculated results. Moreover, existing electrical contact models do not account for the effects of these coatings and CG. This paper proposes an equivalent electrical contact model that accounts for the effects of coatings and CG. Firstly, the Bahrami model was enhanced by integrating heat conduction theory, the “chain-like conductive pathway” theory, and constriction resistance theory to develop an analytical model for electrical contact characteristics. Subsequently, a 3D rough surface geometric model conforming to a Gaussian distribution was generated using Gaussian random functions and an AR-type digital filter. Electrical contact specimens for the contact finger and conductor rod were prepared based on curvature equivalence criteria. The initial contact conditions for static electro-thermal coupling under varying contact pressures were calculated using fluid-structure interaction simulations, enabling analysis of the electro-thermal characteristics of rough surfaces. Finally, the numerical-equivalent electrical-contact model was verified by comparing the F-ECR and F-TCR curves derived from the improved Bahrami model, thermo-electric coupling simulations, and electrical-contact temperature-rise experiments under different contact pressures. The results indicate that the use of coatings and CG significantly reduces the electrical and thermal contact resistances between contact pairs by 46.25% and 1.43% compared with the uncoated and CG-free cases. Contact pressure influences the effectiveness of coatings and CG: reductions in electrical and thermal contact resistance diminish as contact pressure increases. Beyond 60 N, the reduction gradually stabilizes. At 60 N, the reductions in electrical and thermal contact resistance are 27.24% and 96.38%, respectively, compared with the uncoated and CG-free cases, and should be considered in the design of the contact gripping force. Static temperature-rise tests on contact specimens with CG and coatings demonstrate that the improved numerical equivalent-electrical-contact model more closely approximates real-world contact conditions. Future work will focus on improving and analyzing dynamic electrical contact models.
莫狄, 关向雨, 李建成, 舒胜文. 考虑镀层和电力复合脂影响的高压开关触点电热接触特性建模与分析[J]. 电工技术学报, 2026, 41(16): 5639-5650.
Mo Di, Guan Xiangyu, Li Jiancheng, Shu Shengwen. Modeling and Analysis of Electrothermal Contact Characteristics for High-Voltage Switch Contacts Considering the Influence of Coatings and Conductive Grease. Transactions of China Electrotechnical Society, 2026, 41(16): 5639-5650.
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