Company Name: Henan Xinchaoda Cable Co., Ltd.
Contact: Manager Guo
Address: Xibaishui Village, Xitao Town, Wuzhi County
Marketing Center: 1812, Building B, Building 3, Shenglong Plaza, Zhengdong New District, Zhengzhou
Transmission and distribution overhead lines require the sag of conductors during construction and operation. The size of the sag plays a very important role in the safe operation of the line. If the solitary value is not selected properly, the amount of rework and disposal tasks is large and very difficult. Therefore, the reflection and adjustment of the sag stop observation is an important part of the line construction.
Overhead lines are a common method in power transmission lines. In different areas, due to the small temperature drop in the area, the thermal expansion and contraction of the wire causes the wire to sag in the high temperature weather and the tension is too high, causing the wire to break or break; the arc is too large at low temperatures. Make the wire hang down very low, presenting the hidden danger of safety. In addition, if the size of the overhead line is not accurately controlled, it will cause different sag sizes, which will affect the appearance. In overhead line construction, controlling a reasonable amount of sag is one of the key achievements to ensure the safe operation of the line and make the overhead line beautiful in appearance.
The calculation method of the wire length (L), relaxation (F) and safety factor is introduced above.
Regarding the middle and high voltage distribution lines, the span is not large, and evenly, the city is generally around 35 ~ 50m, even in suburbs, villages and special spans, it is usually less than 100m. When the extreme stress of the conductor occurs at extremely high temperatures, In addition, the height of the pole is also very uniform. Both the wire slack F (m) and the wire length L (m) can be calculated according to the following approximate formula, and the error is very small.
F = βℓ2 / 8 (m)
L = ℓ + 8f2 / 3ℓ = ℓ + β2ℓ3 / 24εδ2
Where β is the corresponding specific load [N / (m × mm2)]
Where ℓ is the pitch (m)
The stress of the low point of the ε wire (N / mm2)
The stress ε (N / mm2) at the suspension point of the wire is εδ + βf
The allowable minimum safety factor rules for aluminum stranded wire and steel core aluminum stranded wire are 2.5 in common areas, 3 in important areas, and practices are greater than 3. The rules of copper stranded wires are 2 in ordinary areas, 2.5 in important areas, and practice Between 2.5 and 5. There are many urban residents, and it is necessary to improve the safety factor. For the greening, the pole height is required. At the same time, the high and low voltage distribution lines are generally small. However, the requirements for pole bending moments, cable strength, crossarms, and metal fitting strengths can be greatly reduced, which is generally reasonable.