Development of thermal and structural design technology for a hermetically sealed oil transformer

Abstract

The hermetically sealed oil transformer is designed by applying the expanding function of the tank due to the volume change of the insulation oil according to the temperature rise. When insulation oil expands, increase in the volume of corrugated-fin prevents pressure rise of the transformer. The purpose of this study is to analyze the thermal and structural stability of the transformer to deal with the pressure variation due to the temperature change. For the wind turbine transformer, the vegetable oil transformer has advantages of excellent biodegradation and fire-resistant properties, such as an exceptionally high fire point. Therefore, the design technology of the transformer to deal with the pressure variation has been investigated by fluid structure interaction simulations. The amount of expanded oil inside the corrugated-fin has been estimated for operating load cases, and the design of the corrugated-fin to control the variations of the inside oil pressure has been proposed. Additionally, the structural integrity of a hermetically sealed transformer has been evaluated by both numerical and experimental methods. Hydraulic and thermal tests for the transformer have been performed, and measured values are compared with the analyses results. © 2012 WIT Press.