Simulation of air breakdown mechanism using different electrodes

Abstract

Rapid growth in power sector of nation has given the opportunity to power engineers to protect the power equipment for reliable operation during their operating life. It has been seen from the several studies conducted by power engineers that one of the main problem in high voltage power (HV) equipment is the degradation of insulation i.e., quality of insulation of power equipment. As the high voltage power equipments are mainly subjected with spark over voltage causes by the lighting strokes, switching action, a protective device is used for determine the safe clearance required for proper insulation level. The sphere gaps are commonly used for measurements of peak values of high voltages and have been adopted by IEC and IEEE as a calibration device. Generally, the standard sphere gaps are widely used for protective device in electrical power equipments. The sphere gaps are filled up with insulating medium such as liquid insulation (transformer oil), and gas insulation (SF6, N2, CO2, CCl2F2 etc.) in HV power equipments. Normally, air medium is widely used as an insulating medium in different electrical power equipments as its breakdown strength is 30kV/cm. Therefore electrical breakdown characteristic of small air gap under the different applied voltage has its great significance for the design consideration of various air insulated HV equipment. In addition, the effect of breakdown voltage on different insulation like lamiflex, leatheroid, plywood, craft paper, and polyester fiber has also been studied. To observe the effect on insulation due to breakdown mechanism, the insulation samples are collected both before and after breakdown voltage test and analysis has been done with the help of Scanning electron microscope (SEM). To simulate the air breakdown voltage with and without the insulation barrier has been studied experimentally in high voltage laboratory, a standard diameter of 25 cm spheres are used for measurement of air breakdown voltages and electric field of the high voltage equipments. The above experiment is conducted at the normal temperature and pressure. The simulation of such air breakdown voltage has been carried out in the COMSOL environment. Finally, the experimental result has been compared with theoretical, and simulation results.