Analysis of the Cause of Self-explosion of Glass Insulator of ± 800kV UHVDC Line

In order to study the cause of self-explosion of glass insulators on a ± 800kV UHVDC line. From the perspective of materials, the macromorphology, micromorphology and energy spectrum composition of the self-detonating insulator failure parts were analyzed to determine the cause of the self-explosion of the glass insulator. Through 1:1 simulation modeling, the influence of ambient temperature change on the maximum force of glass insulator is analyzed. The results show that the glass insulator is subjected to tensile force, thermal expansion stress and expansion stress caused by the chemical reaction between the compounds in the cement and water in the environment with large temperature difference and high humidity, coupled with the eccentric gluing of steel feet, glass and steel caps, so that the cement (inside) is the first to be stressed by the steel feet, due to the more pores inside the cement and accompanied by cracks, the cement (inside) cracks under the action of stress, so that the glass is subjected to stress concentration from the end of the crack of the cement (inside). In addition, the glass contains Al2S3 and CaS impurities, and the difference between the impurities and the thermal expansion coefficient of the glass disturbs the stress distribution in the tempered glass, and the two work together to make the glass insulator self-detonate.