Insulation Division Of Oil Immersed Transformers

The insulation of transformers can be divided into internal insulation and external insulation. Internal insulation refers to the insulation of various parts inside the oil tank, while external insulation refers to the insulation between the upper part of the bushing and the ground and between each other. Internal insulation can be divided into two parts: main insulation and longitudinal insulation. The main insulation refers to the insulation between the winding and the grounding part, as well as between the windings. In oil immersed transformers, the oil paper barrier insulation structure is the most commonly used for the main insulation.
The main insulation can be divided into graded insulation and full insulation. Graded insulation refers to the main insulation level near the neutral point of the transformer winding being lower than the insulation level at the end of the winding. On the contrary, if the insulation level at the beginning and end of the transformer is the same, it is called full insulation. Longitudinal insulation refers to the insulation between different parts of the same winding, such as insulation between different wire turns, turns, and turns.