The overhead line mainly refers to the transmission line that is erected on the ground and fixed on the pole and tower with insulators to transmit electric energy.
1. Low voltage conductor 2. Pin insulator 3. Cross arm 4. Low voltage pole, 5. Cross arm 6. High voltage suspension insulator string, 7. Wire clamp, 8. High voltage conductor, 9. High voltage pole, 10. Lightning conductor
To lay overhead lines, the following steps are generally required:
1.Survey and design – the line design shall avoid crossing objects as much as possible and take straight lines. After the route direction is determined, field survey shall be conducted for the sections along the route.
2.Positioning by piles – When positioning, first determine the position, distance and type of the important corner pole, then drive the wooden pile in each pole pit, write the pole number on the wooden pile, and at the same time determine the form of various stay wires.
3.Foundation excavation – before digging electric pole pit, check whether the position of pole pile is correct, and then decide whether to dig circular pit or trapezoidal pit according to the soil quality. If the soil is hard and the pole height is less than 10m, dig a round pit; If the soil is loose and the pole height is more than 10m, three stepped pits shall be excavated.
4.Pole and tower assembly – generally, the pole shall be erected as a whole after the cross arm, insulator, etc. are assembled on the pole on the ground. The speed of pole erection shall be fast and safe. After the pole is erected, the pole surface shall be properly adjusted, and then the earth shall be filled. After the earth is filled to 300 mm, it shall be compacted once. The compaction shall be carried out alternately on two opposite sides of the pole to prevent the pole from shifting or tilting.
5.Stay wire construction – the direction of the stay wire must be the opposite of the unbalanced force. The included angle between the stay wire and the pole is generally 45 degrees, which cannot be less than 30 degrees.
6.Setting out construction – when setting out, put the shaft bar into the reel hole, and then place both ends of the shaft bar on the bracket of the paying off frame. Adjust the paying off frame so that both ends are the same height, and the reel is also off the ground.
7.Conductor erection – each conductor is allowed to have only one joint within each span, but it is required that there shall be no joint between the conductor and the lightning conductor when crossing roads, rivers, railways, important buildings, power lines and communication lines. After the wires are connected, they need to be tightened.
Post time: Dec-22-2022
