The amount of installed cast-resin dry-type transformers has been increasing steadily over the past years due to its wide application range in industrial areas and in the renewable energy sector [1][2]. The lack of mineral oil as an insulating medium allows dry-type transformers to be used in areas with high fire hazards and environmental protection requirements such as in tunnels, buildings or wind
power plants. Therefore, rendering these units more and more important in the electrical grid. However, some well-established diagnostic methods, like DGA, rely on analysing the mineral oil condition. Therefore, it becomes essential to explore alternative diagnostic means, such as partial discharge measurements, to evaluate the insulation condition of in-service dry-type transformers
