Condition monitoring of transformer insulating liquid through service-induced ageing and insulating properties

The insulating system constitutes the foundation of transformer reliability, with the insulating liquid serving as its most vital component. The progressive ageing of this liquid expedites the deterioration of insulation, thereby emphasising the imperative of continuous condition monitoring. Monitoring the key properties of transformer insulating liquids enables early detection of emerging faults and supports timely maintenance, thereby enhancing transformer reliability, safety, and service longevity. This study investigates the effects of service-induced ageing on transformer insulating liquids through a detailed analysis of critical diagnostic parameters. Evaluations performed on insulating liquid samples from in-service transformers of varying operational lifespans demonstrate a systematic and progressive degradation across all measured properties. The findings demonstrate the effectiveness of insulating liquid diagnostics as a reliable tool for assessing condition, tracking ageing progression, and enhancing the service reliability of transformers.