Studies on Contact Degradation Process and Failure Mechanism of GIB Plug-In Connector

Overheating faults of gas-insulated bus (GIB) plug-in connectors induced by contact degradation seriously threaten the safe operation of equipment and power system. Multiphysics coupled numerical simulations and physical experiments were conducted in this article to reveal contact degradation processes of the GIB plug-in connector. First, electromagnetic-thermal-mechanical coupled finite-element (FE) model was built. Relative motion between contact interfaces was considered by low-velocity Stribeck friction model. FE model was verified by physical experiment. Second, influences of operation current, spring stiffness, and conductor insert depth on contact temperature rise were analyzed. Results show that insufficient conductor could induce overheating on several contact spots then accelerate the degradation process. Third, thermal and motion characteristics under cyclic operation currents and short-circuit (SC) current impact were analyzed. Results show that conductor insert depth could be changed by relative motion between contact elements. Relative motion accumulates gradually under cyclic thermal loading by operation current. Significant relative motion and temperature rise could be induced by SC current impact. Finally, progressive and sudden failure mechanisms of the GIB plug-in connector were discussed. Research result may guide optimal design and field maintenance of GIB equipment, and thus improves its reliability.