Study On Oxidation Stability Of Electrical Insulating Oil

In this paper,the basic properties and Hydrocarbon Types of oils were measured.Based on "NB/SH/T 0811-2010 Unused Hydrocarbon Insulating Oil Oxidation Stability Test Method",the changes of experimental conditions were explored.The oxidation conditions of copper wire/164h and 40ppm Fe³⁺/72h were determined for the oxidation experiments.The acid number and sludge quality after oxidation were tested,while the effect of different experimental conditions and the relationship between hydrocarbon structure and oxidation stability was analyzed.The oxidation products were characterized and analyzed,including the change of metal element content in oxidation process by ICP,the composition and content of acidic substances in oxidized oil samples by ESI-MS,and the chemical form and content of main elements in sludge by XPS and GPC.Relative molecular weight and molecular weight distribution of n-heptane insoluble compounds in sludge.In addition,the oxidation experiment of adding trace phenolic antioxidants and theoretical calculation of antioxidants were also carried out,from which the performance of antioxidants and the sensitivity of oils to antioxidants were analyzed.Copper wire has a stronger promoting effect on the formation of acidic substances,while 40 ppmFe³⁺ has a greater promoting effect on the formation of oil sludge.The presence of aromatic hydrocarbons and sulfur can play an antioxidant role in the early stage of oxidation.The high content of straight-chain alkanes is beneficial to the oxidation stability of oil products.Polycyclic naphthenic acid accounts for the majority of the acidic substances formed after oxidation of oil products,which indicates that polycyclic alkanes are more easily oxidized to acidic substances,and branched alkanes are also more easily oxidized to acidic substances.The higher the content of monocyclic aromatic hydrocarbons,the hydrocarbons in oil sludge will the more the accumulation,the higher the content of insoluble matter with high molecular weight,the wider the molecular weight distribution and the deeper the oxidation degree.However,certain amounts of aromatic hydrocarbons and naphthenic hydrocarbons are beneficial to the solubility of sludge.Simulation calculations of antioxidants indicated that the more hydroxyl para-substituted C number of phenolic antioxidants,the higher the antioxidant activity,but the more the branched chains,the worse the antioxidant effect.