Study On The Sulfur Corrosion And Its Effect On Insulation Oil-paper Performance In Transformer Bushing

As the core component of the transformer,the transformer bushing is the key equipment in the power transmission project,and its failure will cause the entire transmission system to stop.Bushing faults is one of the prime reasons causing transformer faults,and the rate tends to increase year by year.Studies have shown that failure of oil-paper insulation is an important reason to result in the failure of transformer bushing.In recent years,an increasing number of insulation failures have occurred induced by corrosive sulfur in insulating oils.Corrosion products can weakens dielectric strength of oil-paper insulation.A large number of domestic and foreign scholars have studied the mechanism of oil-sulfur corrosion and the mechanism that causes faults.While those works are mainly focused on copper winding of transformers,there are few studies on bushing.Bushing has the special structure of“copper-paper-aluminum-oil”and specific operating environment.Therefore,its oil-sulfur corrosion research has certain academic value and engineering significance.In this paper,the bushing model consisting of“copper-paper-aluminum-oil”is taken as the object of study.Around the phenomenon of DBDS corrosion of copper and aluminum,long-term corrosion experiments were conducted.Then the sulfur corrosion of copper and aluminum were explored by electrochemical methods.The influence of corrosion time and DBDS concentration on the corrosion of copper and aluminum foil was studied.The formation of corrosion products in oil and paper was analyzed.At the same time,combining the test results of insulation oil and paper,the effect of sulfur corrosion on the performance of oil and paper were studied.?1?The corrosion degree of copper and aluminum foil was increased with the corrosion time and the concentration of DBDS.The copper corrosion product Cu₂S is deposited on the surface of copper and insulating paper.The contents of copper and aluminum in insulating paper and insulating oil increased with time and the concentration of DBDS.The corrosion tendency and the corrosion rate of copper and aluminum foil was increased with DBDS concentration.?2?Corrosion products of copper and aluminum foils degrades performance of insulating oil and paper.The corrosion products accelerated the aging of insulation paper,which reduced the polymerization degree.The corrosion products on the insulation paper caused the dielectric constant and the dielectric loss and trap density increase,the breakdown field strength decreased.The corrosion products accelerates the aging of the insulating oil,resulting in an increase the acid value,viscosity,and moisture content of the insulating oil.At the same time,the performance of insulating oil is reduced,so that the dielectric loss increases,and the volume resistivity and breakdown voltage decrease.