Thermal Analysis of Different Design of Transformer Fins

Abstract

Electrical power transformer is a static device which transforms electrical energy from one circuit to another without any direct electrical connection and with the help of mutual induction between two windings. It transforms power from one circuit to another without changing its frequency but may be in different voltage level. A power transformer is the electrical device which is used to change the voltage of AC in power transmission system. The first transformer in the world was invented in 1840s. Modern large and medium power transformers consist of oil tank with oil filling in it, the cooling equipment on the tank wall and the active part inside the tank.

The working principle of transformer is very simple. It depends upon Faraday’s law of electromagnetic induction. Actually, mutual induction between two or more winding is responsible for transformation action in an electrical transformer. According to these Faraday’s laws, “Rate of change of flux linkage with respect to time is directly proportional to the induced EMF in a conductor or coil.

As one kind of electrical components, an ideal transformer has no energy losses. However, in reality, a transformer cannot reach a 100% efficient. The main losses come from the winding resistance thermal loss, the eddy current loss and the hysteresis loss For liquid immersed transformer, the active part including cores and windings is immersed in some insulating liquid, usually the transformer oil, filling in the transformer. The heat generated by windings and cores will be transferred to the transformer wall by convection. Then, the heat will dissipate into the environment by radiation and convection. Usually, for some large transformers, fins and radiators are applied for improving the cooling capability. A typical example of the liquid immersed transformers is the large oil immersed transformer in which a blower is installed forcing the circulating air to enhance the cooling effects.