Research On Aging Characteristics Of Composite Insulators Under Typical Climate Conditions

Compared with traditional porcelain and glass insulators,composite insulators have many advantages,such as light weight,low cost,easy installation and good electrical and mechanical characteristics.At present,composite insulators have been widely used in the construction of power grid.However,composite insulators have a problem of aging due to the particularity of their materials.The difference of the environment can lead to the difference of aging mechanism and aging characteristics.Aiming at 3 typical climatic conditions,including high altitude and strong ultraviolet conditions in Tibet,Fujian coastal climate conditions,high humidity or easy condensation conditions,the aging characteristics of composite insulators are studied in depth.The air in the high altitude area of Tibet is very thin,and there is an extremely low ozone center over the Tibetan Plateau,so the ultraviolet radiation in Tibet is very strong.In this paper,hydrophobic test,Fourier transform infrared spectroscopy analysis,thermogravimetric analysis,hardness test were performed on Tibet test films of 10 different processes with different natural ultraviolet aging time.We obtained the final conclusion after data processing and theoretical analysis.The results show that:In the high altitude and strong ultraviolet environment,the content of polymeric siloxane decreases with the increase of aging time;Major chemical groups,such as Si-O-Si,Si-(CH3)2,Si-CH3,C-H,and-OH,will be damaged by ultraviolet radiation in varying degrees;The hardness of the test piece increases year by year,and it is mainly determined by the content of PDMS and ATH;The process of crosslinking and degradation of silicone rubber exist simultaneously in the natural UV aging,and the degree of degradation is greater than that of crosslinking.The chalking rate of composite insulators in the coastal areas of Fujian is higher than that of inland.In view of this phenomenon,the appearance detection and hydrophobicity analysis of the chalking insulators are carried out in this paper,SEM,FTIR and TGA were used to detect the Pollution layer,chalking layer and central layer of the composite parachute skirt,finding out the chalking process and chalking mechanism of that.In this paper,the aging test of NaCl,HNO3 and NaOH solutions of the new composite insulators parachute skirt samples was also carried out.The results were obtained by the hydrophobicity test and FTIR:The static contact angle of the aged samples in salt,acid and alkali solution decreased to low value in the short term and remained relatively stable;Under the same aging time,the concentration of salt solution is not closely related to the static contact angle of the samples;The effect of acid and alkali solution on the hydrophobicity decline of the parachute skirt is greater than that of the salt solution,and the strong alkali solution will make the parachute skirt completely lose the hydrophobicity;The effect of salt solution on Si-O-Si was negligible;When the PH value of acid or alkali solution is the same,the longer the aging time is,the smaller the absorption peak area of Si-O-Si is;When the aging time is the same,the smaller the PH value of the acidic solution or the higher the PH value of the alkaline solution is,the smaller the absorption peak area of Si-O-Si is;The strong alkali solution is more effective than the strong acid solution of the same ion concentration on the aging of parachute skirts.It is easy to condensate dew on insulator surface in areas with large temperature difference or high humidity.In this paper,5 stages of condensation dew on the surface of the compound parachute skirt were found by the ultrasonic spray device and the stereoscopic microscope,including initiating stage of condensation,early development of condensation,the mid-term development of condensation,critical state of condensation,45° slanted slipping state,which providing the factual basis for scholars carrying out related simulationsimulations.At the end of the paper,three kinds of silicone rubber materials,HTV,RTV and LSR,were tested for three kinds of hydrophobicity,and combined with the Young equation and the adhesion work theory,it is believed that the LSR liquid rubber in the area of easy condensation has a good application prospect.