Capacitive Sensor System for Measuring Moisture Content in Transformer Oil

The efficiency and long-term reliability of electrical transformers are highly dependent on the quality of their insulating oil, which serves both as a dielectric medium and a cooling agent. One of the most critical factors affecting transformer oil performance is moisture contamination, which significantly reduces dielectric strength, accelerates aging processes, and increases the probability of insulation breakdown. The purpose of this study is to develop and analyze a reliable method for monitoring the water content in transformer oil. A capacitive sensor system was designed and applied to measure variations in dielectric permittivity caused by different levels of moisture concentration. Experimental measurements were carried out using transformer oil samples with controlled humidity levels, and the obtained results demonstrated a clear correlation between the sensor output and the actual water content. The proposed method provides a simple, accurate, and real-time monitoring approach, which can be effectively used for predictive maintenance and ensuring the safe operation of power transformers.