Experimental Study Of Composite Insulators On Long-term Performance

Recently with the rapid development of our country's industry, the dunghill evacuated into air has been increasing more and more resulting in the deterioration of environment. Our country's air pollution will still be serious for a long time. The insulation level of power system's outside porcelain in being and the traditional method preventing pollution flashover just by clearing cannot be seasoned with the varity of air condition. They them also cannot withstand the attack of bad weather condition. The continuous happening of pollution flashover accident with large ares have been a main threaten to our country's power system.Silicon rubber composite insulators have many favourable advantages such as without needing to check zero, without needing to clear, light weight, easy for tranport and installation owing to their hydrophobicity and hydrophobic transfer. Composite insulators have been widely used in power system since 1990s and have been one of major effective approaches preventing pollution flashover accident. Nearly more than 3 million composite insulators have been put in use at present, with the longest running time approximating 20 years.More than 300 thousand composite insulators have been used in ShanDong Power Grid, with the longest running time near 18 years. Their electrical and mechanical performance degrade under the collective force including the humidity, partial discharge, corona, ultraviolet radiation, chemical and biologic erosion during operation. There have been continuous information about the flashover, the degrading of the electrical intensity, breakdown, and brittle fracture, degradation, bird damage of the composite insulators all over the country, whereas the composite insulators are still in the state of no maintenance.The reliability of them under different manufacturer, different running time, different environment, and various craftwork is a worrying problem. How to monitor and estimate the composite insulators' whole performance, and make use of them in the right manner are desire for the power utility.Analyzing the working performance of composite insulators and their mechanical and electrical performance, physical performance of the material under different environment and manufacturer, making certain of their aging state, estimating the using life in advance are strictly necessary. Establishing the guideline for the choosing, checking, transport, installing, and examination for the composite insulators in work in order to avoid or diminish the accident caused by the improper of maintenance and using and eventually result in the stable operation of power grid.This paper have done much job based upon the test focusing on the reliability of composite insulators in work includeing the electrical performance, mechanical performance and aging performance.The relationship between the hydrophobicity and the dirtiness degree, the running time, and the environment are investigated via studying the hydrophobicity of the composite insulators in work in the clean area, in the littoral and in the industrial ditryness area of suburb. Different maintenance method are proposed via studing the impact of the temperature, deposit density, electrical field intensity, working environment and the type of dirty on the hydrophobicity. A new method measuring the composite insulators' whole contamination degree are put up through researching the natural contamination depositing characteristics of the composite insulators under different environment and studing the contribution rate of the contamination which is tough to clean to the total deposit density.All of the electrical performance of the composite insulators, their reliability, the difference of dry and wet flash frequency voltage are investigated through the shock voltage test, waterlogging tolerance test with frequency voltage, dry and wet flash test with frequency voltage. New artificial contamination test method which can reproduce the weaken hydrophobicity actually are proposed via probing into the artificial fog frequency voltage tests of composite insulators. The comparison of the new and traditional method are taken with tests. The transformation of contamination, diacharge, ablation, leakage current, rigidity and so on during aging are studied based on the 5000h artificial accelerated aging test on the compostie insulators in work. The performance estimation of composite insulators are proposed. Residual mechanical performance and mechanical stability of composite insulators in the inner wedge type are investigated. The impact of pulling force and torque on the mechanical performance are discussed. The mechanical performance of composite insulators in the outer wedge type and their residual strength are analyzed. Some judgement of the mechanical stability of the them are also provided. The mechanical performance of the composite insulators in the extrusion type are analyzed. The relative mechanical performance tracking system and dynaminc load stability are investigated. The mechanical stability of the composite insulators with different end connection craftworks are discussed. The requirement for the checking of mechanical performance of the composite insulators are proposed.Finally, the suggestions for the using of composite insulators are presented for guide.