Research On The Aging Characteristics Of Composite Insulator Based On TG-FTIR

With the large number of composite insulators put into operation,the line faults caused by the aging of composite insulators are increasing,which seriously threaten the safe and reliable operation of the power grid,and bring great difficulties to the operation and maintenance of power supply companies.Therefore,research on the aging of rubber materials has important academic value and engineering necessity.Based on the Thermogravimetric analysis-Fourier transform infrared spectromerer(TG-FTIR)test,this paper studied the aging performance of composite insulator sheds,the TG and pyrolysis gas phase products of the three main components of the composite insulator sheds,the new composite insulator sample,and the composite insulator sheds sample after used.Proposed a aging evaluation method based on TG-FTIR test,and used the Fourier Infrared Spectroscopy(FTIR)test to verify the feasibility of this aging evaluation method.First,the three main components of the composite insulator sheds and the new composite insulator sheds samples that have not been put into use were subjected to a TG-FTIR test.Analyzed the thermal weight loss curve of the main component,and the gas phase carbon black had almost no weight loss.Large weight loss of aluminum hydroxide occurs between 220℃ and 360℃,and weight loss of polydimethylsiloxane occurs between 360℃ and 570℃.FTIR results of gas phase products show that pyrolysis of gas phase white carbon black generates a small amount of water vapor and carbon dioxide,dehydration reaction of aluminum hydroxide generates water vapor,and the pyrolysis process of polydimethylsiloxane undergoes cracking,crosslinking and condensation reactions,products a small amount of water vapor,carbon dioxide,methane gas,a large number of Si-O-Si gas phase molecules,and gases such as alkanes,alcohols,phenols,ethers,and lipids.The results of the combined TG-FTIR of the new sample correspond to the results of the main component.The thermal weight loss curve is divided into four stages,and the second and third stages have obvious weight loss,corresponding to the aluminum hydroxide and polydimethyl dimethyl in the three components.Pyrolysis of siloxane;the types of gas phase products and the temperature of each gas production are the same as the results of FTIR analysis of the main component.Secondly,based on the TG-FTIR test to study the aging characteristics of the composite insulator sheds after operation,the test results show that the aging sheds has a smaller total thermal weight loss than the unaged sheds.Although the types of gas-phase products remain unchanged,the yield of each gas-phase product decreases,and a K value calculation method is proposed based on the combined TG-FTIR test results to evaluate the aging degree of the sheds and perform preliminary verification.The effects of the depth of the sheds,the electric field strength,and the operating life on the age of the sheds are studied.The results show that the same layer of sheds has different depths on the lower layer than the inner layer;the sheds running on the high-voltage side with the same insulator is the most severe;The longer the operating time of different insulators,the more severe the aging.The above results are highly consistent with the FTIR test results,and are consistent with the conclusions of the aging characteristics of composite insulator umbrella skirts studied by previous people,which proves the feasibility of using TG-FTIR in combination with the aging characteristics of composite insulator sheds.