Cable products with only conductors but no insulation layer are called bare conductor products. The most widely used conductors today are copper and aluminum. Aluminum conductors include AAC/AAAC/ACSR/ACAR/AACSR, aluminum-clad steel, etc.
Bare Conductor typically has at least 7 strands; center in the middle with 6 surrounding strands.More flexible wires commonly have 19, 37, or 49 strands. Very large wires, or those manufactured for very flexible applications, may have 70 or more strands.
Bare Conductor can be divided into three types from the structure
1. It is made of single wire of single metal material, such as aluminum stranded wire, copper stranded wire, aluminum alloy stranded wire, etc;
AAAC (All Aluminum Alloy Conductor)
AAC (All Aluminum Conductor)
AAAC has good creep resistance, high elongation and high temperature characteristics. According to the standard value, the elongation of aluminum wire is 2 times of that of aluminum wire (1.5%), and the actual test value can reach 7% ~ 8%. It has excellent overload capacity and fatigue characteristics. At high temperature, the strength loss is small, and the high temperature operation plays the role of artificial aging, increasing the conductivity by 2% ~ 5%;
2. Steel cored aluminum strand with steel strand as core wire to increase tensile strength and one or more layers of aluminum wire or aluminum alloy wire twisted on the outside;
ACSR (Aluminum Conductor Steel Reinforced)
AACSR (All aluminum Alloy Conductor Steel Reinforced)
ACSR is the most widely used variety. Because the steel core bears the tensile force suspended on the pole, the distance between poles can be increased to reduce the investment (especially for high-voltage lines), prolong the life of the conductor and enhance the safety.
If there is corrosive gas around the laying line (such as salt fog by the sea, chemical plant area), anticorrosive steel cored aluminum strand coated with anticorrosive coating shall be used.
3. Stranded wire made of bimetal single wire, such as aluminum clad steel stranded wire.
Aluminum clad steel wire is a kind of bimetallic wire which continuously and evenly covers aluminum on the steel core. It has the advantages of good conductivity, corrosion resistance, high frequency transmission performance and high strength of steel. Aluminum clad steel cored aluminum stranded wire is a kind of stranded wire which uses aluminum clad steel wire as reinforcing core and aluminum wire together. Compared with ordinary steel cored aluminum stranded wire, the conductor weight is light, the current carrying capacity is increased by 2-3, and the power loss is reduced by 4-6; It has a long service life and does not increase any erection cost. It is widely used in transmission lines, especially in coastal areas, salt marshes and industrial areas with grade III and IV pollution, and in transmission and distribution lines with increasing section ratio of aluminum to steel
Aluminum clad steel wire is divided into six groups according to the conductivity: 20c, 23ac, 27ac, 30C, 33A, 40C, and the corresponding conductivity is 20.3%, 23%, 27%, 30%, 3% and 40% IACS
The development trend of bare conductor
① On the premise of not increasing the dead weight of conductor, increase the tensile capacity and vibration resistance, such as high strength aluminum alloy stranded wire, self damping (anti vibration) conductor, etc;
② Increase the long-term working temperature or conductivity of conductor to increase the transmission capacity, such as double capacity conductor, etc;
③ Anti ice and snow conductor to prevent conductor surface from freezing in cold area