Interfacial electro-thermal runaway dynamics in medium voltage AC conductor sleeves

Abstract

Introduction: Tracking and electro-thermal runaway are critical failure mechanisms in overhead conductor sleeves that compromise the safety and reliability of power transmission systems. The geometric configuration of sleeve overlaps plays a significant role in determining susceptibility to these phenomena. This study investigates the influence of 90° and 180° overlap configurations on the initiation and progression of electrical tracking and thermal runaway under alternating current (AC) stress. Methodology: A combined experimental and simulation-based approach was employed. A novel experimental setup was developed to measure surface and interfacial conductivity of sleeve materials under varying thermal and electrical conditions. Interface Tracking Inception Voltage (ITIV) was evaluated for both configurations. Additionally, Finite Element Method (FEM)-based simulations were conducted to model electro-thermal behavior, incorporating the dependency of conductivity on temperature and electric field. Results: Experimental findings revealed that the 90° overlap configuration exhibited earlier tracking onset and higher susceptibility to thermal runaway compared to the 180° configuration. The ITIV was consistently lower for 90° overlaps. Simulation results supported the experimental observations, showing greater thermal and electrical stress concentration in 90° overlaps. Comparative analysis with traditional covered conductors (CCs) and conductor sleeves (CS) confirmed the advantages of optimized overlap designs. Discussion: The study highlights the critical role of overlap geometry in improving the performance of overhead conductor sleeves. The 180° configuration demonstrated superior stability, reduced tracking events, and better resistance to electro-thermal degradation. These insights offer practical recommendations for enhancing the design of conductor sleeves, with direct implications for improving reliability and reducing the maintenance costs of power transmission infrastructure.