Research on the Influencing Factors of Counter-Strike Lightning Resistance Level of 500kV Transmission Lines

With the continuous acceleration of the urban-rural integration process, the construction quality of the rural power grid is directly related to the vital interests of the general public and has an impact on the economic development of the entire rural area. Currently, 10kV distribution transformers and box transformers are the most widely used power equipment in the rural power distribution system, and they also require the most operation and maintenance. They are key control objects for ensuring the quality of rural power projects. During the implementation of the power grid renovation project, the number of distribution transformers in use is increasing. Moreover, higher requirements are put forward for the installation quality of distribution transformers and box transformers. Both the selection of distribution transformers and the construction and installation process affect the safety and stability of the entire power supply system and are closely related to the service life of the transformers in the future. Therefore, how to ensure the rationality of the installation of distribution transformers is a key aspect in the construction of the power distribution network.

Preparation Work before the Construction and Installation of 10kV Distribution Transformers and Box Transformers

Before installing a distribution transformer, the preliminary preparation work needs to be done, which includes selecting a suitable transformer, preparing installation equipment and materials, and improving the preparation and inspection work before the construction operation. Generally speaking, when selecting a distribution transformer, the model and capacity of the distribution transformer should be considered, that is, a distribution transformer with low power consumption, high performance, and the ability to meet the power consumption requirements of users should be selected. Before installing 10kV distribution transformers and box transformers, the construction design drawings should be prepared, the approval of construction procedures and relevant materials should be completed, and construction equipment and materials with qualified quality and meeting the construction conditions, such as ready mixed paint, anti-rust paint, and welding electrodes, should be ready, thus laying a solid foundation for the construction of the distribution transformer. In addition, waterproof measures should be taken in advance on the roof or wall where the distribution transformer is installed to ensure that there is no leakage during the construction process and in future use. The holes and embedded parts should be cleaned according to the construction drawings, which is also an important part of the installation construction of the distribution transformer. Before the official construction, relevant technicians should be organized to inspect the transformer equipment after unpacking, which includes checking the spare parts of the transformer and the information on the equipment nameplate, etc., to ensure that the distribution transformer meets the design requirements, facilitate the subsequent construction process, and improve the installation quality of the transformer.

Key Points of the Construction and Installation of 10kV Distribution Transformers and Box Transformers
Installation of the Transformer Bracket
Currently, in order to ensure the stable operation of the 10kV distribution network, a bracket transformer with a capacity of 500kVA needs to be installed in the distribution network, and the distance between each bracket should be about 2.5m, and the utility pole should be fixed with channel steel. It should be noted that each utility pole needs to be equipped with a piece of channel steel, and one piece of channel steel cannot be used to fix multiple utility poles. In addition, since the distribution transformer is installed on the utility pole, the distribution transformer should be kept parallel to the utility pole as much as possible, and the installation inclination angle should be strictly controlled to be less than 20mm. Words indicating "electrical hazard" should be marked on it to play a warning role.
Installation of the Drop-out Fuse
As an important component of the distribution transformer, the fuse is generally installed on the high-voltage side and the low-voltage side of the transformer. In order to ensure that the fuse wire of the fuse can fall safely to the ground after fusing, the axis of the fuse should maintain a certain angle with the ground. Among them, the vertical distance between the fuse on the high-voltage side and the ground should be greater than 4.5m, and the horizontal distance between each fuse should be more than 0.5m. For the drop-out fuse on the low-voltage side, the vertical distance between its bottom and the ground should be more than 3.5m, and the horizontal distance between it and other fuses should be about 0.2m.
Installation of the Grounding Device and the Lightning Arrester
Currently, the main cause of problems in distribution transformers is lightning accidents. Especially during the thunderstorm season, lightning phenomena occur frequently, greatly increasing the probability of the power system being struck by lightning. Therefore, in order to avoid lightning accidents, installing a grounding device and a lightning arrester in the distribution transformer is a very effective solution.

•  When installing the grounding device, a reasonable grounding resistance should be set to prevent the grounding resistance of the transformer from increasing abruptly due to lightning strikes, which could cause the electrical energy generated by lightning to damage the power equipment.
• The lightning arrester is also one of the necessary devices for preventing lightning disasters and improving the stability of the power system. Generally, the lightning arrester should be directly connected to the transmission line, and the other end should be connected to the ground, so as to quickly conduct the high voltage generated by lightning into the ground and prevent the transformer from being burned out.
• In order to reduce the occurrence of lightning disasters on the transmission line, a lightning arrester should also be installed between the fuse on the high-voltage side and the transformer. At the same time, it can achieve the purpose of extending the maintenance time.

Common Problems during the Construction of 10kV Distribution Transformers
During the installation of 10kV distribution transformers, two problems may be encountered:

• The quality problem of the casing porcelain parts;
• The oil leakage problem of the oil tank of the distribution transformer. Generally, most of the casing porcelain parts used in distribution transformers have sharp edges and corners, and damage often occurs during transportation or installation. Once the damaged positions exceed two or the damaged area exceeds 5‰ of the total area, the casing porcelain parts should be replaced in a timely manner to avoid potential safety hazards. For the oil leakage problem of the oil tank of the distribution transformer, it is mostly caused by the incomplete sealing of the oil tank, which is also one of the problems with a relatively high occurrence rate during the installation of the transformer. The occurrence of this problem not only affects the safe construction of the transformer but also brings great difficulties to the maintenance work of the transformer. If such a problem occurs during the installation construction, the oil leakage position should be determined first, the cause of the oil leakage should be found, and repair work should be carried out. As can be seen from the above, before using the distributor, the welded and threaded joints should be carefully inspected to prevent oil leakage caused by poor sealing.

Conclusion
In conclusion, in order to extend the service life of 10kV distribution transformers and box transformers and ensure the reliability of the operation of the distribution network, the primary task is to ensure the installation quality of the distribution transformers and promptly solve various problems that may occur during the construction process. Based on this, only by correctly installing according to the construction key points of 10kV distribution transformers and box transformers can the power transformers fully play their application functions, meet the different power consumption requirements of users, and maintain the safe and stable operation of the power grid.