The iron core and winding are immersed in the oil tank filled with transformer oil, and the end points of each winding are led to the outside of the oil tank through insulating bushings, so as to connect with the external lines. Therefore,Oil immersed power transformer is mainly composed of five parts: 1. iron core; 2. Winding with insulation; 3. Transformer oil; 4. Oil tank; 5. Insulating sleeve.

Iron core: The iron core of the transformer is the magnetic circuit of the transformer. Since the magnetic flux in the transformer core is an alternating magnetic flux, in order to reduce eddy current loss, the transformer core is laminated with electrical steel sheets.

Winding: according to the arrangement method of windings in the iron core, transformers can be divided into iron core type and iron shell type. The basic types of transformer windings are the same core type and overlapping type. The iron core type transformer is commonly used with the same core type winding, and the iron shell type transformer is commonly used with the overlapping type winding.