Research On Corrosion Micro-mechanism Of Sulfur On Transformer Oil-paper Insulation And Protection Technique

In recent decades,hundreds of insulation accidents due to corrosive sulfur in transformer oil has been reportedat home and abroad,which attracts extensive attention of electric power department and relative researchers.At present,a number of experimental studies were launched on corrosion damage mechanism of sulfur and infuence law of the insulation properties.At the same time,a method,adding metal passivor into the transformer oil to delay the copper winding corrosion was put forward and has engineering applications.However,due to the limitations of experimental research,the demage mechanism of corrosive sulfur on oil-paper insulation is still unclear.Furthermore,effective concentration of metal passivor and influencing factors of protective effectiveness both in new and used oil still to be explored.Therefore,it is of great academic and engineering value to research the microcosmic deterioration mechanism of corrosive sulfur on oil-paper insulating and to explore the protection law against sulfur corrosion.Using molecular dynamics simulation technology,the sulfide-cellulose models were built based on fiber mechanics,mean square displacement,total molecular energy calculation.The microcosmic mechanism of different sulphide on cellulose paper was researched.It was found that the mechanical rigidity and toughness of cellulose weakened by H2 S and Hexadecanethiol and the higher the concentration of sulfide the toughness decreased more obviously.While these two sulfides significantly reduced the glass transition temperature of the cellulose a nd the calculation of the mean square displacement of cellulose showed that the molecular chain motion is more intense and the stability was worse.The total energy and non-bond energy calculations of the cellulose molecules showed that sulfide did not increase the total energy and electrostatic energy,but H2 S and Hexadecanethiol caused hydrogen bond and van der Waals effect weaken.So a view from energy aspect was given to explain the reasons for mechanical properties decline of cellulose.At the same time,an experiment was designed and carried out on oil-paper aging adding corrosive sulfide.We got the law which is consistent with the simulation by measuring the degree of polymerization and tensile strength of insulating paper.In order to get the best concentration of metal passivor adding in the used and new oil,the comparative aging tests of different concentrations were carried out.The measurement of transformer oil characteristic parameters such as dielectric loss factor,breakdown voltage,miosture and furfural content was conducted.As the result indicates,under the optimal dosage,the effect of passivator on the properties of oil and insulation paper meet the criteria.In the meantime,under the temperature of 130 ? no matter in the used oil or new oil,the protection effect of these two kinds of passivator declines significantly,and its effect was apparently influenced by moisture and oxygen content.