1500 kva 3 phase Electrial oil Immersed transformer

During the normal operation of a 1500 kva 3 phase Electrial oil Immersed transformer, the electric field formed between the energized windings, leads, and the oil tank is a non-uniform electric field. The iron core and its metal components are all in this electric field. Due to the different potentials induced by static electricity, the floating potentials of the iron core and its metal components are also different. When the potential difference between two points is high enough to break down the insulation between them, spark discharge occurs. This kind of discharge can decompose the transformer oil and damage the solid insulation. To avoid this situation, the iron core and its metal components must be reliably grounded.

The iron core must be grounded at one point. When the iron core or other metal components are grounded at two or more points, a closed loop will be formed between the grounding points, resulting in a circulating current. This current can sometimes be as high as several tens of amperes, which will cause local overheating, lead to oil decomposition, and may even melt the grounding strip and damage the iron core. All these are not allowed. Therefore, the iron core must be grounded, and it must be grounded at one point.