Analysis of Degradation and Mechanism of Insulating Characteristics of Transformer Bushings in Humid Environments
To investigate the degradation and mechanism of insulating characteristics of transformer bushings under hot and humid conditions,high voltage dielectric loss,capacitance,and Frequency Domain Spectroscopy(FDS)tests were performed on oil-paper insulated bushings that had developed defects after long-term operation in such environments,at various temperatures and voltages.The defective bushings were dissected for sampling,and the water content and degree of polymerization of the paper samples were tested to analyze the bushings'moisture-induced aging process.The results showed that high voltage dielectric loss,capacitance,and FDS tests could significantly reflect the presence of moisture-induced aging defects inside the bushings.Compared to normal bushings,the defective bushings demonstrated a stronger correlation between high voltage dielectric loss,capacitance and the applied voltage and temperature,with an increase in tan δ across the entire frequency range in FDS,a change in the curve shape,and an increase in capacitance values.The main moisture-affected parts of the bushing were the sealing ring at the head of the conductor rod and the end screen,with most of the moisture being absorbed by the insulating paper.Areas with high moisture content were concentrated at the lower end of the capacitor core and the innermost layer.Under the combined effects of moisture and external high temperature,the insulating paper aged more rapidly,leading to discharges.This study provides a reference for the optimized design and operational maintenance of bushings in hot and humid environments.
hot and humid environmenttransformer bushingshigh voltage dielectric lossfrequency domain spectroscopydegradation mechanism
万方数据
维普
