Technical development and future perspectives on the application and performance of dielectric liquids

In this paper, the recent trends of electrical insulation in liquid dielectrics am described. The development results of the higher stress/compact design equipment, environment-friendly ester-oil, insulation diagnostic technique, higher temperature application, etc., as well as cryogenic electrical insulation are introduced. In particular, it is pointed out that the charge carriers in liquid dielectrics will be a key factor to control the higher stress electrical insulation and therefore the basic research on charge behavior and the physical mechanism should be extended for the future.