Research on the Characteristics of Partial Discharge Gas Generation in Typical Defects of Oil Immersed Current Transformers

During the operation of oil-immersed current transformers, they gradually deteriorate due to various factors. In order to study the relationship between partial discharge and gas generation characteristics under different typical defects, this paper measures the unit-time discharge energy, unit-time apparent discharge quantity, pulse repetition rate, and gas generation rate during the discharge development process of three typical defects: protrusion defect, surface defect, and gas gap defect. It is found that the generation of hydrocarbon gases and hydrogen in the oil mainly depends on discharges with an apparent discharge quantity above 300pC. Among the discharge characteristics, the unit-time discharge energy and unit-time average discharge quantity have a more significant impact on the gas generation rate than the pulse repetition rate. The discharge characteristics greatly influence the generation rates of C2H4, C2H2, and H2 in protrusion defect, CH4, C2H2, and H2 in surface defect, and CH4 and H2 in gas gap defect. The study of gas generation characteristics provides a reference for diagnosing current transformers.