OPTIMAL SHAPE DESIGN OF THE HV WINDING OF A TEST TRANSFORMER

In the paper, attention is focused on a class of single-phase transfor mers that are employed when a high-voltage withstand test is required for verifying the quality of the dielectric insulation of a given comp onent. The HV winding of this kind of transformer is made up of severa l layers, characterized by height that decreases along with the increa se of the voltage profile in order to keep the distance between windin g and ground within acceptable limits. Therefore, the designer of such devices is mainly concerned with the shaping of the HV winding; start ing from a tentative configuration, he has to find the winding shape s uch that the electric breakdown cannot occur, at the same time keeping the volume of oil and active materials as small as possible. Traditio nally, the design is developed by means of a trial-and-error approach based on a sequence of field analyses, varying a design variable at a time; the-paper shows how the design problem can be solved more effici ently by optimizing the profile of the winding in an automatic way.