Insulated overhead conductor is a kind of transmission facility which helps to transmit electricity and is useful in the process of power transmission.Insulated overhead conductor is to add a circle of tightly wound aluminum wire outside the steel core, so that the good transmission performance of the metal can help transmission equipment to work better, play a role in strengthening transmission, generally used in transmission cables and other places.When using insulated overhead wire, it is necessary to pay attention to electric shock, because the function of this equipment to transmit electricity is very strong, if the installation or use of the equipment is not in accordance with the use and installation of standard specifications, it is easy to cause electric shock installation personnel, it will be very dangerous.
The so-called insulated overhead wire is relative to the cable said that the tower is set up by the wire at a certain height to transmit electrical energy lines.For high voltage distribution grid insulation overhead wires of insulation is usually by air, before the distribution circuit (10 kv below 380 v) generally also USES bare wires, but due to the complexity of urban distribution environment, short circuit grounding and lightning line often happen, results in the decrease of the power supply reliability, so the current general under 10 kv insulated overhead conductor were using insulated wires (i.e., wire insulation outer package), the so-called insulation overhead wires.
Insulated overhead conductor is the insulation material according to its tolerance voltage level requirements, with different thickness wrapped in the conductor outside, playing a role in making the wire and external isolation.Insulation overhead wire in power, there will be heating phenomenon, therefore, the more ideal insulation material should have good insulation and thermal conductivity, should be in heat resistance, aging resistance, mechanical properties and other aspects of a good advantage.
Insulation materials used for insulated overhead conductor are generally weather-resistant polyvinyl chloride, polyethylene, high-density polyethylene, cross-linked polyethylene, etc., which are black mixtures.These insulating materials have the following characteristics:
(1) polyvinyl chloride insulation material (PVC) : insulated overhead wire has good electrical and mechanical properties, stable performance to acid and alkali organic chemical components, moisture resistance, flame retardant, low cost and easy to process.However, compared with other insulating materials, the insulation resistance is low and the heat resistance is poor.The allowed working temperature should not be greater than 70 ° C for a long time.Therefore, the insulated overhead conductor of PVC insulation material is generally only applicable to the outer sheath of low-voltage insulated conductor or clustered insulated conductor.
(2) polyethylene insulation material (PE) : it has excellent electrical properties, good chemical stability, good solubility at room temperature, very stable performance on non-oxygenic acids and bases, and good moisture and cold resistance.But PVC insulated overhead conductor of the insulating material softening temperature is lower, its long-term allowed working temperature should not exceed 70 ° C.In addition, the resistance to environmental stress cracking, oil and climate resistance is poor, and not flame retardant.
(3) high density polyethylene insulation material (HDPE) : insulated overhead conductor in addition to long-term allows the merits of this kind of material temperature should not exceed 70 ° C and flame retardant, other main electrical and mechanical performance and crosslinked polyethylene material close to.
Instructions for use of overhead conductors
Overhead conductors is in compression, copper, aluminum conductor outer extruding shield and weather resistance type crosslinked polyethylene or syndrome type black high density polyethylene or weather resistance type made by PVC insulation layer and the outer screen (no inside and outside the LKV overhead insulated cable shielding layer), simple structure, safe to rely on, at the same time, it has excellent mechanical and physical properties and electrical properties, resistance to electric mark, creeping discharge, atmospheric resistance performance is good, compared with the wire tree, laying small gap, saving line corridors, line voltage is reduced, especially to reduce the power supply accidents, ensure the personal safety.
Overhead conductors are not ordinary oil-paper insulated cables, nor are ordinary cross-linked insulated cables directly hung on overhead wires.General overhead cables are single core according to his structure can be divided into hard aluminium wire, hard wire structure, the structure of a variety of ways, hard aluminium wire structure is lighter and moderate tension, cable is easy to bend, installation is more convenient, and his cost is low, can be installed in the existing tower above casually, so now the line is usually use this structure.
Overhead conductors are characterized by simple structure, convenient erection and maintenance, low cost of lines, large transmission capacity, and convenient laying across rivers, valleys and other special geographical conditions. They have good electrical conductivity, sufficient mechanical strength, large tensile strength, and magnifying tower rod distance.Therefore overhead conductors are widely used in overhead transmission and distribution lines of various voltage levels.
The products of overhead conductor are weather-resistant crosslinked polyethylene, weather-resistant high-density polyethylene and weather-resistant polyvinyl chloride (PVC).Its structure is simple, safe and reliable, and has excellent mechanical and electrical properties.Good resistance to electric mark, surface discharge and atmosphere.Compared with the bare wire, the overhead wire is suitable for urban, rural, mountainous, forest and mining areas. It is a new product of all-weather overhead wire.
Requirements for use of overhead conductor:
1. Empty wire laying, environment temperature should not be below - 20 ℃, below 20 ℃, laying an empty conductor must be heating in advance.
2. When laying overhead conductors, the bending radius of insulated overhead conductors with rated voltage of 1kV shall not be less than 6 times the outer diameter of the overhead conductors, and 101kV and 35KV overhead conductors shall not be less than 15 times the outer diameter.
3. The erection method of overhead wire shall be the same as that of bare overhead wire, and it shall still be fixed on the insulator of crossarm, but the distance may be appropriately reduced.
4. Overhead wire shall be used in conjunction with specially designed overhead wire metal instruments.
5. During the laying, construction and storage process, attention should be paid to the sealing of the end of the empty conductor to prevent water from the overhead conductor and reduce its performance.
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