Study On Heavy Rain Test Method Of Composite Insulator

Due to the increase of heavy rainfall,rain flashover accidents of composite insulators occur frequently under heavy rainfall conditions.At the same time,the test method of composite insulators under heavy rainfall conditions is imperfect,which may lead to low efficiency and inaccurate results of experiments.In this thesis,the method of pollution,the time of rain test and the statistical evaluation of the rain flashover test results of composite insulators are studied.(1)Spraying contamination test was carried out on composite post insulators,and several key steps of the spraying method were given.The relation curves and function relationship between salt-ash density on the upper and lower surfaces of insulator sheds and the concentration of contaminated solution were obtained,and the trend of the curves was compared and analyzed.The thesis also analyzed the influence of insulator material on the contamination curve.The repeatability of the spraying method was verified by non-repetitive two-factor variance analysis.By comparing the spraying method with the quantitative brushing method,the author proposed that the spraying method can be used to contaminate large composite post insulators in order to improve the efficiency of the experiment.(2)The loss of polluted soluble salt on the surface of composite insulators under heavy rainfall was studied,from which the double exponential decay function model of polluted soluble salt loss was obtained.The model was verified under different rainfall intensity and shed structure,and the significance of different exponents of the model was given.It is found that kaolin and diatomite have similar effects on the loss of contaminated soluble salt on the surface of composite insulators.The retention effect of composite materials on contaminated soluble salt is better than that of glass and porcelain.The gelatin can retard the loss of polluted soluble salts on the surface of composite insulators to a certain extent,and it plays a role mainly in delaying the dissolution and flushing rate of rain in the period of the loss of salt on lower surface and pole.When the density of gelatin is 0.05mg/cm~2,the delaying effect reaches the maximum.Salt on the surface of composite insulators will not be lost completely.According to the implicit function of rainfall intensity I and the minimum rainfall time t that reaches the stable value of salt density,the minimum rain test time under different rainfall intensity was obtained.(3)The outlier test was carried out for the rain flashover voltage values of three groups of composite post insulators obtained by uniform boost method under heavy rainfall conditions.The Shapiro-Wilk test method was used to prove that the flashover voltage of composite post insulators in rain obeys normal distribution,and the results were verified by MATLAB.Since the rani flashover voltage obeys normal distribution,the author analyzed the minimum test times of uniform boost method for composite post insulators and found that the minimum test times are between 18 and 20.