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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 lighter 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.