Effects of electric field accretion due to water droplets piling up across and inside damaged housing cracks in HV field-aged insulators

Ensuring the long-term reliability of High Voltage Insulators (HVIs) is essential for maintaining the stability and performance of power transmission systems, especially under conditions of severe environmental and climatic stress. This study investigates the effects of electric field intensification resulting from the accumulation of water droplets in damaged housing cracks of field-aged composite polymer insulators used in HV power systems. Composite polymer insulators, favored over traditional ceramic alternatives because of their superior hydrophobicity and mechanical resilience, nevertheless suffer degradation when exposed to harsh environments. This research analyzes real field-aged insulators retrieved from a 380 kV substation in Saudi Arabia. Electric field simulations highlight the critical influence of crack geometry, position, filler material such as air and water, and water droplet size on localized electric field intensity. The results reveal that air-filled cracks with water droplets above produce the highest electric field intensification, substantially exceeding the levels observed in water-filled cracks or pristine conditions. Water droplets markedly exacerbate electric stress, creating conditions conducive to partial discharges, corona inception, and accelerated aging. Shanks’ cracks create the severest electric field peaks compared to sheds top and bottom cracks, as shanks, in contrast to sheds, are parallel to the electric field direction. These findings emphasize the need for rigorous monitoring of insulator condition, early identification of hydrophobicity loss and crack formation, and proactive maintenance to mitigate severe local field intensification. Ultimately, understanding these degradation mechanisms assists in designing more robust insulators and improving preventive strategies in high voltage infrastructure management.