Effect of local overheating on the insulation performance of epoxy resin impregnated paper bushings

• Published in: 2024 4th Power System and Green Energy Conference (PSGEC) pp. 1025 - 1030
• Main Authors: Xu, Zuoming, Hu, Wei, Yin, Pengbo, Xie, Xiongjie, Liu, Yang, Long, Tao
• Format: Conference Proceeding
• Language: English
• Published: IEEE 22.08.2024
• Subjects: Capacitance; Carbonization; Crack; Dielectrics; Epoxy resin impregnated paper bushing; Epoxy resins; Frequency-domain analysis; Frequency-domain dielectric spectroscopy; Gasification; Insulators; Local overheating; Power systems; Resistance; Temperature distribution; Testing
• DOI: 10.1109/PSGEC62376.2024.10721074

To study the internal temperature distribution of epoxy resin impregnated paper (RIP) bushings under load current conditions and the impact of local overheating on the insulation performance of the bushings, a synchronous test circuit for bushing temperature rise and insulation performance was constructed. The study obtained the variation patterns of the bushing hot spot temperature and the corresponding insulation performance under different currents and simulated the process of local overheating fault in RIP bushings. Test results indicate that when the hottest spot temperature in the bushing is below 100℃, the relaxation polarization loss in the insulation medium is evident. The tanδ-frequent variation curve exhibits loss "peaks" and "valleys", and the curve shifts towards higher frequencies with increasing of temperature. When the hottest spot temperature exceeds 120℃, the conductive loss in the insulation medium becomes prominent, and the tanδ-frequent variation curve shows a linear decreasing trend in the logarithmic coordinate system. A hottest spot temperature exceeding 140℃ will damage the internal insulation of the bushing, leading to a sharp increase in tanδ and capacitance while the insulation resistance drastically decreases after returning to room temperature. When the hottest spot temperature exceeds 200℃, a large amount of gas will be generated inside the bushing. Local overheating cause carbonization and cracking of the bushing core, which lead to a sudden increase in tanδ and a sharp decrease in capacitance. This study can provide a reference for the optimization design, testing, and operational status evaluation of bushings.