Overhead lines, sometimes referred to as Aerial conductors, are often specified where there is significant distances to cover and where these cables are best positioned far out of reach. The distances to cover, the environmental conditions it will face, and the location are all factors in specifying the appropriate cable.
The main classifications of bare conductor are AAC (All Aluminium Conductor), AAAC (All Aluminium Alloy Conductor) or ACSR (Aluminium Conductor Steel Reinforced). AAC is most commonly found in urban areas with frequent supports and short spans. It is also used in coastal regions where salt in the air can cause corrosion - the All Aluminium wire providing corrosion resistance - and specified for use in the railway industry for OHL electrification. AAAC tend to be specified where greater mechanical resistance is required and where there is a reduced sag characteristic. The ACSR, with its steel reinforcement provides additional strength and where the spans run for larger distances, such as across rivers.
The advantages of AAC, AAAC and ACSR come in their lightweight properties. These overhead lines have no specified voltage rating - it will depend on the type of installation - although the higher corona limit of ACSR makes it beneficial when used with high voltage and extra-high voltage transmission. The overhead line wires are manufactured in accordance with various national standards and can be sized appropriately - including ASTM B231, TS IEC 1089, DIN 48201, BS 215, and Spanish standard UNE 21.018.
Also within the family of Overhead Lines are Aerial Bundle Cables. These low voltage and medium voltage cables, abbreviated as ABC, are wrapped in insulation, with the medium voltage variants also having an outer sheath. They lay up and twist multiple insulated single cores together - medium voltage ABC also tend to have a steel wire support running through the centre for applications including street lighting and secondary pole to pole service cables. They're also often used in temporary power installations in the construction industry. The insulation provides a protective barrier in the event of sparks or shorts.
Concentric lay stranded Aluminium Conductor ( AAC) is made up of one or more strands of hard drawn 1350 aluminum alloy. These conductors are used in low, medium and high voltage overhead lines. AAC has seen extensive use in urban areas where spans are usually short but high conductivity us required. The excellent corrosion resistance of aluminium has made AAC a conductor of choice in coastal areas. Because of its relatively poor strength to weight ratio, AAC had limited use in transmission lines and rural distribution because of long spans utilized.
Midal can manufacture & supply AAC on Non returnable wooden / steel reels or Returnable steel reels.
Features
high Current Carrying Capacity
excellent resistance to corrosion
Ideal for use in coastal area
Used as bare overhead transmission conductor and as primary and secondary distribution conductor and messenger support. ACSR offers optimal strength for line design. Variable steel core stranding enables desired strength to be achieved without sacrificing ampacity. Temperature for continuous use can be up to 75ºC.
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