Conductors are mainly made up of Copper, Aluminium and their alloys.
Stranded Conductors
- Greater flexibility and mechanical strength than the single wire of same crossectional area.
Total number of conductor is a strand of n layer = 1 + 3n(n + 1)
Overall diameter of stranded conductor = (2n + 1)d
where, d = diameter of each strand.
Types of Conductor
1. Hard drawn Aluminium conductor
- It is also called All-Aluminium conductor (AAC).
- For given resistance, the Al conductor cross-section is 60% greater than that of Cu and its weight is only 48.3% of Cu conductor.
- handling, transportation, and erection become economical.
- corona effect reduces due to higher conductor diameter.
- used for distribution lines in urban areas.
- Lightness, large diameter and greater sag more likely to swing and resulting in interphase faults.
- failure of the conductor through fatigue when there is the wind.
2. Aluminium conductor Steel Reinforced (ACSR)
- have steel core
- strong mechanically for a construction of long span lines.
- high tensile strength and light weight.
- small sag i.e. line design with shorter supports or longer spans.
- higher cross-section enables to increase corona inception level.
- insulators and other fittings needed are less.
- breakdown possibility is reduced.
Disadvantages of ACSR Conductor
- difficulty in making spikes and dead ends.
- corrosion due to an electrochemical action between Al and steel core.
3. Compacted ACSR Conductor
- It is also called as smooth body ACSR conductor
- ACSR conductor is pressed through dies to flatten the aluminium strands into segmented shape and forms compacted ACSR conductor.
- diameter is reduced.
4. Expanded ACSR Conductor
- plastic or fibrous material is introduced between the steel core and Al strands to make the diameter of the conductor large to reduce corona loss and radio interference.
5. All Aluminium Alloy Conductor (AAAC)
- Homogeneous Al alloy conductor
- good tensile strength and conductivity
- one alloy is Silmalec (0.5% Si, 0.5% Mg and rest Al)
- one alloy is 5005 (0.8% Mg and rest Al and impurities(not exceed 0.55%))
6. Aluminium Conductor Alloy reinforced conductor (ACAR)
- a central core of alloy of Al surrounded by layers of conductor Al.
- gives better conductance
- small size and lesser weight.
7. Alumoweld Conductor
- Al powder is welded on to a high strength steel wire.
- 75% area of the conductor is covered by Al.
- more costly than SCA conductor.
- used as earth wire.
8. Phosphor-Bronze Conductor
- it is used as a conductor material for very long spans such as river crossings.
- more strong than Cu conductor
- low conductivity may be improved by using a cadmium copper core
- superior for atmospheres containing harmful gases like ammonia.
9. Galvanized steel conductor
- high strength
- used on very long spans
- being a magnetic material, a galvanized steel conductor has the large resistance, inductance and voltage drop.
- comparatively short life.
