A brief introduction to towers

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Pole towers are supports used to support transmission lines in overhead transmission lines. Pole towers are mainly made of steel or reinforced concrete and are the main support structures for overhead transmission lines. A tower is a pole or tower-like structure that supports overhead transmission lines and overhead ground lines and maintains a distance between them and the ground. Pole towers all over the world use steel structure, wood structure and reinforced concrete structure.

Wooden and reinforced concrete pole-like structures are often called poles, and tower-like steel structures and reinforced concrete chimney-like structures are called towers. Pole towers without cables are called self-supporting towers, and towers with cables are called cable towers. China lacks timber resources and does not use wooden poles. But good achievements have been made in the manufacture of reinforced concrete rods and reinforced concrete chimney-shaped spanning towers using the centrifugal principle.

Pole tower is one of the basic equipment in overhead distribution lines. Depending on the material used, they can be divided into three types: wooden poles, cement poles and metal poles. Cement poles have the advantages of long service life and small maintenance workload, and are widely used. The most commonly used cement rod is the toggle rod, and the taper is usually 1/75. It is divided into ordinary reinforced concrete rods and prestressed reinforced concrete rods.

The grounding of transmission line towers is very important for the safe and stable operation of the power system. Reducing the grounding resistance of the tower is the main measure to improve the lightning resistance level of the line and reduce the lightning trip rate of the line. Lightning accidents caused by poor grounding of towers account for a large proportion of the line failure rate. This is mainly due to the fact that when lightning strikes the top of a utility pole or lightning protection line, the lightning current enters the ground through the tower grounding equipment. The ground resistance is too high, resulting in a high counterattack voltage. That said, most poles and towers that are prone to lightning strikes have high grounding resistance. There are many reasons for the high ground resistance of towers, including design reasons, construction reasons, and operation and maintenance reasons. However, external natural conditions, such as high soil resistivity, complex geological conditions and construction inconvenience are the main reasons.

The lightning trip rate of the transmission line is closely related to the grounding resistance of the transmission line tower. The parts with high grounding resistance of transmission line towers are often the parts with complex terrain, inconvenient transportation and high soil resistivity. These places are usually areas of intense lightning. Therefore, it is a very difficult task for us to study the reasons for the high grounding resistance of towers and take effective measures to reduce the grounding resistance of towers.


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