TRANSMISSION LINE CONDUCTORS COMPARISON TUTORIALS

These aerial cables consist of separate conductors which use spacing between conductors to obtain a voltage rating. There are three major types of aerial conductors used for electrical transmission and distribution.

AAC - All Aluminium Conductor 
AAAC - All Aluminium Alloy Conductor 
ACSR - Aluminium Conductor Steel Reinforced 

The choice of conductor is determined by current rating and stringing
conditions (span length, sag, everyday stress, ambient temperature and wind velocity, and worst case conditions of wind and ice). Conductor characteristics such as strength to weight ratio, ultimate tensile strength, modulus of elasticity, area, coefficient of linear expansion, AC resistance will determine the most suitable conductor.

AAC - All Aluminium Conductor is made up of one or more strands of hard drawn 1350 Aluminium Alloy. Because of its relatively poor strength-to-weight ratio, AAC has had limited use in transmission lines and rural distribution because of the long spans utilized. However, AAC has seen extensive use in urban areas where spans are usually short but high conductivity is required. The excellent corrosion resistance of aluminium has made AAC a conductor of choice in coastal areas.

ACSR - Aluminium Conductor Steel Reinforced consists of a solid or stranded steel core surrounded by one or more layers of strands of 1350 aluminium. The high-strength ACSR 8/1, 12/7 and 16/19 strandings, are used mostly for overhead ground wires, extra long spans, river crossings, etc. The inner core wires of ACSR may be of zinc coated (galvanized) steel.

AAAC(1120) - A high strength Aluminium-Magnesium-Silicon Alloy cable was developed to replace the high strength 6/1 ACSR conductors. This alloy conductor offers excellent electrical characteristics, excellent sag-tension characteristics and superior corrosion resistance to that of ACSR.

Equivalent aluminum alloy conductors have approximately the same ampacity and strength as their ACSR counterparts with a much improved strength-to-weight ratio,and also exhibit substantially better electrical loss characteristics than their equivalent single layer ACSR constructions. The thermal coefficient of expansion is greater than that of ACSR.

As compared to ACSR, AAAC's ligher weight, comparable strength and current carrying capacity, lower electrical losses and superior corrosion resistance have given this conductor wide acceptance as a distribution conductor. It has found limited use, however, as a transmission conductor.

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