Hello! Welcome to the website of Dongguan pinye Electronics Co., Ltd!

This can not only effectively protect the transformer, but also facilitate maintenance. In addition, in order to prevent the intrusion of reverse conversion wave and lightning wave on the low voltage side, a low voltage arrester should also be installed on the low voltage side. In order to avoid the voltage drop of lightning current on the grounding resistance and the residual voltage of the lightning arrester superimposed on the transformer insulation, the grounding terminal of the lightning arrester, the shell of the transformer skeleton and the neutral point on the low voltage side should be connected together by multi-strand copper-core plastic wires with a cross section of not less than 25mm2, and then connected with the lead-in wire of the grounding device.
4. Grounding device At present, in the rural power grid reconstruction, there are many small-capacity transformers in rural areas, and 10kV distribution transformers are often struck by lightning in thunderstorm season. Because the grounding resistance is too large, it can not reach the specified value in the regulations, and the lightning current can not be quickly discharged into the earth, resulting in excessive residual voltage of lightning arrester itself, or high voltage drop on the grounding resistance, resulting in transformer burning accident. Therefore, the grounding resistance of the grounding device must conform to the specified value of the regulations. For 10kV distribution transformer: the capacity is below 100kVA, and its grounding resistance should not be greater than 10Ω; When the capacity is above 100kVA, the grounding resistance should not be greater than 4 ω. Grounding resistance test shall be carried out after grounding device construction is completed, and backfill soil can be carried out only after passing the test.
At the same time, the shell of the transformer skeleton must be well grounded, and the shell grounding should be tightened with bolts, and it should not be welded directly for maintenance. The underground part of the grounding device is composed of horizontal grounding body and vertical grounding body. The horizontal grounding body adopts a 40×4mm flat steel with a length of 6m, while the vertical grounding body adopts three L50×50×5mm angle steels with a length of 2m to be welded with the horizontal grounding body respectively. The horizontal grounding body is buried 0.6～0.8m deep in the soil, while the vertical grounding body is driven into the ground on the basis of the horizontal grounding body. 40×4mm flat steel is used for grounding lead-in. For the convenience of testing and power safety, the connection point of lead-in should be located in the channel steel under the transformer for the transformer installed on the column.
5. The new and reconstructed drop wires of transformer substation shall adopt multi-strand insulated wires, and its cross section shall be selected according to the rated capacity of transformer skeleton. However, the copper core and aluminum core of the high-voltage side drop wires shall not be less than 16mm2 and 25mm2, and the use of single-strand wires and unqualified wires shall be avoided. At the same time, we should consider the safety distance between the drop line and the surrounding buildings.