Condition estimate of contacts of current-carrying conductor in GIS based on the FEM calculation of temperature field

In Gas Insulated Switchgear (GIS) the loop resistance is a key parameter which can characterize the contact condition of the conductive circuit. The current method to measure loop resistance was mostly proposed and used in routine test, commissioning test and overhaul. The monitoring of abnormal conditions of contacts in operation has not been realized yet. To early detect the hidden contact defects in conductive circuit of the operating GIS and avoid serious accidents, in this paper a novel method to predict the loop resistance of the current-carrying conductor based on the finite element method (FEM) Calculation of Temperature Field is presented. Combined with the structure, working characteristics and contact features of the GIS current-carrying conductor, a multi-physics heat transfer model was set-up coupled electromagnetic field, flow field and temperature field. Meanwhile, with the model an FEM algorithm for solving the steady and transient temperature field was designed and its availability and reliability was verified by comparing the simulation results with the experimental ones. Then different contact conditions were set and the corresponding temperature rise characteristics were obtained. The mapping relationship between the loop resistance and the temperature rise was determined. So in the last the prediction of the contact state of GIS current-carrying conductor according to the temperature factor was accomplished, which could provide a new detecting tool for GIS state maintenance.