Transient electromagnetic force analysis of GIS bus based on FEM

Gas insulated switchgear (GIS) is widely used for its good economic benefits. But mechanical faults caused by electromagnetic force occur occasionally. The conducting wire and the metal shell are exposed in the alternating electromagnetic field, which is caused by the load current and vortex. This leads to electromagnetic force because of electromagnetic induction. So it is necessary to analyze the electromagnetic force. Aiming at the working three phase enclosed horizontal gas insulated bus (GIB), the electromagnetic force of the wire was calculated by principles of electromagnetism. A two-dimensional numerical calculation model of horizontal GIB bestirred by three-phase power frequency current source was built with the finite element method (FEM) software ANSYS. By exerting alternating current excitation transient electromagnetic analysis was conducted. The spatial distribution and time-varying characteristics of magnetic strength and electromagnetic force of the conducting wire and metal shell were obtained. Results show magnetic lines are absolutely restrained in the shell and inner magnetic field changes periodically with its distribution closely related to the load current. Both the wire and the shell suffer electromagnetic force. The force is depended on the load current and the nodal location, and its size and direction vary periodically with the frequency twice that of the excitation. The calculation model and analysis results can be used for the force and vibration analysis of GIS, condition monitoring and fault diagnosis.