Transformer Oil Dielectric Characteristics in Microwave Assisted Reconditioning Processes

Maintenance of transformer oil is needed to maintain the quality of power service. Thermal heating and filtering are the main ways to remove contaminants from the oil. In this research, a preliminary study was carried out using microwaves as thermal heaters in the reconditioning process of used transformer oil. The reconditioning process is carried out by filtering and thermal heating varies from temperatures of 40–100 °C using a microwave oven. Dielectric characteristics are shown by analyzing breakdown voltage, dielectric power loss, viscosity, and dc conductivity measurements. The amount of moisture content is also taken into account in measuring the level of thermal efficiency of the heater. Under the influence of microwaves, an increase in the characteristics of the dielectric strength in the form of an increase in breakdown voltage reaches 140.50%. Microwave heating is very good in reducing the water content in oil with a level of thermal efficiency reaching 25.55–40.40%. Removal of contaminants is better done by microwaves characterized by a decrease in the value of the dielectric power loss and dc conductivity at each treatment.