Touqeer Ahmad Raza, Muhammad Kamran, Farooq Khurum Shehzad, Farhan Sadiq, Imran Shakir, Majid Niaz Akhtar, Syed Ahtisham Mehmood Shah
Outdoor ceramic insulators are subjected to electromechanical and electrochemical stresses, as well as internal discharges, owing to high voltages and contaminants. Over time, the relative proportions of the material evolve, and in conjunction with erosion, surface characteristics deviate from their initial state. In this study, real in-service disc insulators were collected from an industrial zone and tested for flashover voltage (FOV) under dry conditions. Scanning electron microscopy (SEM) was used to observe surface anomalies. SEM images revealed that the surface of the affected disc was irregular, with microsized cavities (~12 μm) that facilitate retention of water droplets on the surface. Moreover, energy-dispersive x-ray (EDX) analysis was performed to a depth of 0.3 cm to identify any changes in the insulator surface composition. EDX analysis showed that the amounts of silicon dioxide (SiO2) and aluminum oxide (Al2O3) had diminished, which indicates a reduction in insulating strength from its normal performance. A relatively high percentage of undesirable rubidium oxide was found on the surface of the affected insulator, which can react with water to form RbOH. Such elements, in combination with granules/cracks, facilitate surface conductivity and hence lead to premature flashover. COMSOL simulation was also performed by placing discrete water droplets and cavities on the surface to inspect the electric field behavior. Simulation results showed spikes in the electric field, consistent with the experimental findings. This study provides valuable insights into the role of surface condition in flashover phenomena and paves the way for the development of coating materials for insulating surfaces. © The Minerals, Metals & Materials Society 2026.
Department of Electrical Engineering, University of Engineering and Technology, Lahore, 54890, Pakistan; Department of Electrical Engineering and Technology, Muhammad Nawaz Sharif University of Engineering and Technology, Multan, 60600, Pakistan; Department of Chemistry, Emerson University Multan, Multan, 60000, Pakistan; Department of Basic Sciences and Humanities, Muhammad Nawaz Sharif University of Engineering and Technology, Multan, 60600, Pakistan; Department of Physics, Faculty of Science, Islamic University of Madina, Madina, 42351, Saudi Arabia; Institute of Physics, The Islamia University of Bahawalpur, Bahawalpur, 63100, Pakistan; The Islamia University of Bahawalpur, Bahawalpur, 63100, Pakistan; Mechanical and Industrial Engineering Department, Engineering Faculty, Universitas Negeri Malang, Malang, 65145, Indonesia
