Finite Element Analysis of Surface Abrasion Defect of Main Insulation for HV Motor Stator Winding

During the operation of high voltage (HV) motor, the main insulation can be deteriorated and generate insulation defects. For instance, the insulation surface can be abraded due to mechanical stress. As a result, these defects, which are with poor dielectric property, become the local concentrations of electric stress. Besides, the environment around the insulation system is complicated and changeable, which changes the distribution of electrical field and electrical potential. In this paper, the finite element analysis (FEA) simulation was used to study the distribution of the electric potential, electrical field and current density of the 10kV stator windings with different abrasion thicknesses at different temperatures. The simulation results show that the more severe the insulation abrasion, the higher the electric field strength and current density in the copper conductor. The higher the ambient temperature, the higher the electric field strength and the lower the current density in the copper conductor. When the insulating material at the junction of the semi-conductive coating and the graded stress coating is abraded 1.56 mm at the temperature of 120°c, the current density and electric field strength in the copper conductor will suddenly increase. Besides, this paper also studies the propagation behavior of the current pulse signal after it is injected into the insulation defect of the winding. The simulation results show that the charge, the field intensity and the current density are all attenuate with the propagation of the signal.