We usually see in highway or farmland near tower lines of 220KV, more careful you must find some horizontal or vertical slices of cake and wire together, this thing called insulator string. The 220kV line is generally 16-17 pieces of insulator string, and the number of overhanging insulators is 1 less than the former.(Much bigger than you think)
However, the 500kV line needs a full 28 pieces, and the physical requirements of the tower are very high. The tower itself has height, and the influence of the air flow on the line is also considered. In the "gentle" climate of the eastern plains, it is not easy to insulate 500kV Line, and it is tricky to think about in the "grumpy" Tibetan plateau.
The insulation level of 500kV Line is much higher than 220kV Line, because the relationship between insulation grade and voltage level is exponentially increasing. The basic properties of insulators include electrical, mechanical and thermal properties. In addition, there are environmental and aging resistance. When the voltage level of the insulator is raised, the size and weight of the insulator are increased correspondingly, but the electrical and mechanical properties are not increased in proportion and the heat resistance decreases rapidly. Therefore, it is especially difficult to make insulators with high voltage grade.
220kV line 17*2 string insulators.
High altitude cable transportation method: solve high altitude material transportation problem.
It can’t destroy the fragile ecological environment of Tibetan areas, but also to overcome all kinds of risks. The electric power workers are also struggling to come up with some ingenious ideas. The transport equipment has also been specially improved. It is thought that more than 2,700 bases will be erected on the whole line of the project, and about 60 percent of the towers will have no roads. What if the transporter doesn't go in? In all, about 300, 000 tons of supplies are carried by manpower and brute force, probably for the rest of their lives.
For this reason, Chinese engineers have specially developed the mountain cable-way transportation method, which is similar to the construction of the 500 meter aperture spherical telescope in Guizhou. Alpine cable, with the help of terrain and pulleys, perfectly solved the problem of high mountains on materials. It is not difficult to go up the mountain with a single ton of towers.
In addition, in a desert land, traffic is difficult, but encountered sandstorms easily disoriented, and "the last kilometer" through the conveyor, can locate, loss and avoid the car, and they want to come out of the coup.
Instead of flat, flat ground, the towers can only stand on top of the mountain.Generally on the ordinary ground, we all make a point of stability, the four legs of the tower should stand on a plane, so that it is more stable and convenient for construction. If the mountain tower is built, we can use the way of blasting the mountain to blast out the flat area for construction.
But networking engineering thermal fluid activity via meadow, alpine valleys, alpine desert, plateau topography complex area, in particular, it through the southwest of China's second largest forest area, forest, unique vulnerable ecological system, if the first Fried stone can cause ecological destruction and soil erosion.
Therefore, according to different climate and topography, the builders have designed 13 series of different electric towers. The largest of these is known as the "high and low leg" electric tower. The longest leg of the tower and the shortest leg is more than 30 meters, or 10 stories tall.
Each leg has a different length, so each one is designed separately. Without excavating the work surface and construction road, the workers will climb to the position of the electric tower to carry out the construction, the tower material will be transported to the mountain by the cableway.