Feasibility demonstration of EGLA online condition assessment: Electrical-thermal characterization of the semiconductive connection unit

Externally gapped line arresters(EGLA) are lightning protection equipment with wide applications and excellent performance, but the structure of its external gap restricts the development of its online condition assessment. In view of this problem, this paper proposes an EGLA online condition assessment scheme that generates leakage current by short-circuiting the external gap with a semiconductive connection unit and focusing on the design of the connection unit. Firstly, this paper analyzes the requirements for the characteristics of the connection unit. Subsequently, the semiconductive composites with nonlinear resistive properties are selected as the connection unit and their composition and geometry are designed. Next, experiments simulating the scenario of complete EGLA failure are designed to verify the performance of the connection unit. According to the experiment results, the designed connection unit shows good current limiting performance at lower test voltages (≤5.3 kV). However, at higher test voltages (≥8.7 kV), high-temperature failure of the connection unit occurs after a certain period of access, this paper attributes the cause to the partial overheating caused by the aggregation of current lines. Therefore, this paper also analyzes the safety checking time when using the connection unit, providing theoretical support for the development of EGLA online condition assessment.