1.Changsha University of Science and Technology;2.Electric Power Research Institute of State Grid Hunan Electric Power Company;3.Maintenance Company of Hunan Electrical Power Corporation
In order to study the breaking mechanism of 10kV overhead insulated lines by lightning, an ablation model of insulated conductors was established based on COMSOL, and the ablation status of the conductors when subjected to lightning current and power frequency short-circuit current was simulated. Then the force model of the wire is established to analyze the force when the wire is ablated. According to the simulation results, the lightning current only leaves a perforation in the wire insulation; if the influence of external forces is not considered, the power frequency arc can ablate and fuse the insulated wire in 1.3s. The mechanical simulation results of the insulated wire show that the tension of the wire at the ablation site undergoes abrupt changes and is affected by the electromotive force between the wires and the electromagnetic thrust of the arc. Combined with theoretical analysis, it is concluded that the main reason for the wire breakage caused by lightning is the plastic deformation and brittle fracture of the wire under the combined action of heat and mechanics. The simulation research provides a reference for lightning protection of 10kV overhead insulated wires.