What is a linear tower

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The straight pole tower refers to the pole tower used for the straight section of the overhead line. The wires are suspended by hanging clips, pin or post insulators. The design form of the straight tower of the AC UHV transmission line mainly adopts the cat head tower, and the conductors are arranged in the middle phase "V" string and the side phase "I" string. The vertical distance between the middle phase conductor and the lower phase conductor is about 16m, and the horizontal distance between the two phase conductors is about 30m. Therefore, the line corridor can be reduced to a certain extent. In order to save line corridors and reduce demolition costs, such cat-head linear towers are usually used.

The main form of linear pole tower is the cat head tower. Except for some towers near the UHV Jingmen substation and the large span of the Han River, some other towers are in the form of wine glass towers. Many plains and hilly areas have thatched pagodas. Let's analyze the cat head linear tower.

According to the operating experience of 500kV transmission lines, in addition to the design wind speed, vertical load in gears and tower clearance, the wind deflection problem should also be emphasized when calculating the wind deflection angle of the insulator string. In the actual operation of the 500kV line, there is a phenomenon that the electric wire discharges to the main body of the linear tower due to the excessive wind deflection angle. The key to the calculation of the wind deflection angle is the value of the wind pressure coefficient, which will be discussed based on the operation and maintenance experience of ultra-high voltage transmission lines.

Due to the towers and towers of the AC UHV line, the span, vertical span and horizontal span are also large, and the line does not pass through the micro-weather area. Generally, the possibility of wind deflection on AC UHV lines is relatively small. In the practice of long-term operation of 500kV lines, auxiliary measures such as installing heavy hammers have been adopted, which have a certain effect on restraining wind deviation. On the other hand, in the design of the cat-head linear tower, for the division and division of the meteorological area along the line, corresponding technical measures can be taken according to the specific conditions of each section or even each file, and the safety factor and design of the line can be taken according to the specific situation. Margin components can be appropriately increased.

Since the occurrence of wind-conducting faults is usually random, the influence of micro-topography on wind speed and the laws of disastrous weather such as local strong winds should be further studied, so as to improve the level of wind direction and reduce the wind deflection of transmission lines of linear towers.


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