Overhead lines are generally divided into low-pressure and high-pressure two, low-voltage overhead lines are generally four, was a zigzag arrangement, the high pressure is three, was tug-shaped arrangement, the tower must be high-voltage lines, Low-voltage lines are generally used with a leather line, and now rarely used, replaced by cables, high-voltage lines are bare lines, the core for the wire, the appearance of aluminum, commonly known as ACSR. Overhead cable also called the cable, not called overhead lines.
Overhead lines, literally understood is the frame in the air of the wire. The cable on the pole can not be an overhead line, it is only the overhead of the cable laying. Overhead Cable General overhead lines are bare wires (no insulation outside). 10kV and above the overhead lines are three (on behalf of A, B, C three-phase), if it is 6, then the general double back. 380V overhead lines are generally four, on behalf of A, B, C three-phase plus an N line (or zero line)
Overhead line is through the tower, the cement tower tower in the air of the wire, usually bare wire. Overhead line low cost, but occupied area is large, Overhead Cable for the current main line type. Overhead lines from the wire, lightning lines, towers, insulators and fittings and other components of the wire: transmission of lightning lines: the lightning current into the earth to protect the power lines from the lightning tower: support wire and lightning protection insulators: the wire and the tower between the insulation Fittings: support, connect, protect wires and lightning bars, connect and protect insulators.
Are generally high-voltage lines using overhead cables, high-voltage lines because the ground is very high, in order to reduce costs, therefore, and the choice of bare wire, if it is in the ground or from the building is very close to the case, must choose insulation cable. High voltage lines in the high voltage, Overhead Cable the current is very large, easy to heat, will burn insulation, and even breakdown insulation. Under high pressure, some of the original insulation materials, such as rubber, plastic, dry wood, etc. will become a conductor, can not afford insulation.
If you still pack the high-voltage line insulation, Overhead Cable it is necessary to spend more money, wasted money and things. High-voltage wire surface does not contain insulation, put it hanging in the high tower, it may be due to contact with the tower and leakage. In order to prevent this phenomenon, high-voltage wire is always hanging in a long string of good insulation under the porcelain, so that high-voltage lines and insulation tower. High-voltage overhead lines are generally a group of three, that is, we often say that the three-phase line. Low-voltage overhead line directly used is insulated single-core cable, not bare wire, because more than a zero line, so it is four.
Overhead cable for AC rated voltage 1-10KV power transmission and distribution system, 1KV GB12527-90 and GB1179-83 standard 10KV GB14049-93 and GB1179-83 standard.
Overhead cable lines are divided into hanging overhead cable lines and self-supporting overhead cable lines.
Suspension overhead cable line laying include: hanging line selection, installation of hanging plywood, laying hanging line, hanging line connection, do the end (dead head), tighten the hanging line and so on.
Erection of hanging all-plastic cable lines are pre-linked hook method, Overhead Cable moving pulley edge edge hanging method, set the pulley traction method and the car traction pulley care method.
Self-supporting overhead cable lines, do not need to set up another hanging line and hanging cable hook, but must use self-supporting special iron, as long as the installation of the curved plywood device can lay the cable, and then tighten the self- terminal.
The overhead cable includes a cable conductor, a shield layer and a conductor insulation layer, the shielding layer is arranged outside the cable conductor, the conductor insulating layer is arranged outside the shielding layer, and the cable conductor is provided with a reinforcing core, Overhead Cable A reinforcing layer is arranged between the cable conductor and the shielding layer, and an elastic layer is arranged between the reinforcing layer and the cable conductor. The reinforcing cable and the reinforcing layer can increase the tensile strength of the cable in the aerial cable provided by the utility model, and the elastic layer can prevent the extrusion of the cable conductor; it has the advantages of low cost, simple structure and wide application range.