Insulation type of aluminum alloy cable

At present, aluminum alloy cables are developing very rapidly in China, but we rarely see relevant articles on the selection of aluminum alloy cables. This time, we will talk about the selection principles of insulation types and sheath types of aluminum alloy ACSR Cables.

Selection of cable insulation type
The selection of cable insulation type shall comply with the following provisions:
1) Under the service voltage, working current and its characteristics and environmental conditions, the insulation characteristics of the cable shall not be less than the conventional expected service life.
2) It should be selected according to the reliability of operation, the simplicity of construction and maintenance, and the comprehensive economy of the maximum allowable working temperature and cost
3) It shall meet the requirements of fire prevention places and be conducive to safety.
4) When it is clear that it is necessary to coordinate with environmental protection, the cable insulation type that conforms to environmental protection should be selected.
5) It is recommended to select the type of XLPE insulation. For 6kV important circuits or XLPE cables above 6kV, the form of three-layer coextrusion process characteristics of inner and outer semiconductions and insulation layers should be selected.

Selection of cable sheath type

  1. General principles for selection of cable sheath
    1) When it is necessary to enhance the external force resistance of the single core cable of the AC system, the non-magnetic metal armor layer shall be selected, and the steel armor without effective non-magnetic treatment shall not be selected.
    2) Polyethylene outer protective layer is recommended for the metal layer, reinforcing layer and armor of cables laid in humid, chemical corrosive environment or prone to water immersion environment.
    3) In densely populated public facilities and places with low toxicity, flame retardancy and fire prevention requirements, polyolefin and other halogen-free outer protective layers can be selected, and PVC outer protective layers should not be selected.
    4) Except for low temperature environment below -15 ℃ or places soaked in medicinal chemical liquids, and the extruded outer sheath of cables with low toxicity and flame retardancy requirements should be polyethylene, others can choose PVC outer sheath.
    5) Aluminum alloy cable is installed in the building with interlocking armor of aluminum alloy tape, which can replace the bridge and improve the bending performance and compression resistance of the cable. If it is used in outdoor wet places, the outer sheath needs to be extruded.
  2. Relevant regulations on the selection of cable sheath during direct burial laying
    1) When the cable bears large pressure or there is a risk of mechanical damage, it should have a reinforcing layer or metal tape armour.
    2) In the quicksand layer, backfill soil zone and other soil where displacement may occur, the cable shall be armored with steel wire.
    3) For extruded cables used in areas where termites seriously harm, the outer protective layer with higher hardness should be selected, and the thin outer protective layer with higher hardness can also be extruded on the ordinary outer protective layer. Its material can be nylon or special polyolefin copolymer, or metal sleeve or steel strip armor.
    4) Polyethylene outer sheath should be used in areas with high groundwater level.
    5) In addition to the above cases, the outer protective layer without armor can be selected.
  3. Relevant regulations on the selection of cable sheath for fixed laying in the air
    1) When the extruded insulated cable with small cross-sectional area is laid directly on the arm support, it should have steel tape armor.
    2) In underground passenger transport, commercial facilities and other places with high safety requirements and serious rodent damage, plastic insulated cables should have metal tape or steel tape armor.
    3) When the cable is under the stress condition of high drop, the multi-core cable shall have steel wire armor, and the AC single core cable shall adopt non-magnetic metal wire armor.
    4) Cables laid on bridges and other densely supported cables may not contain armor.
    5) When it is clearly necessary to coordinate with environmental protection, PVC outer protective layer shall not be used.
    6) When laying in buildings, aluminum alloy tape interlocking armor can be used instead of cable tray laying.
    Remarks: cables laid in protective tubes should have extruded outer sheath.
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