Most of the faults in overhead power supply systems occur due to failure in transmission
lines, resulting in immense loss and inconvenience to consumers. The main weakness
of overhead lines are that its power carrying conductors are bare.To overcome the
above deficiency, Aerial Bunched Cables systems have been introduced at many places
across the world for both HT and LT systems.
Principally, the system is a compromise between insulated power cable systems and
bare overhead conductor systems. As far as basic construction goes, there are three
or four power carrying conductors suitably insulated and laid around a bare or insulated
weight-carrying conductor, which also serves as earth/neutral conductor. The cable
is then hanged on transmission poles/towers suitably. Since the cores are insulated
the chances of faults reduces to a great extent.
Power and Neutral Cores : Here, the conductor is composed of H2 or H4 grade
Aluminium of Class 2 grade to IS: 8130/84. Popular sizes are 16mm2 to 95mm2. Again,
insulation can be either crosslinked Polyethylene or Polyethylene.
Messenger Conductor : These are made of either galvanized Steel or Aluminium
Core Identification : Either by number printing or by ridges on insulated
Specification : REC specification no.32/1984 an IS: 14255/1995 deals exclusively
with LT aerial bunched cables. Additionally, customers have developed their own
specification according to their specific needs.
Strong Points : In comparision to bare overhead lines, aerial bunched cable
has very high degree of safety and reliability due to the conductors being insulated
with the best dielectric medium. This ensures good protection against ground and
line faults leading to considerable increase in system efficiency as against bare
overhead lines. The problem of free-clearance is also minimized.
Tampering with power-line like hooking also gets eliminated resulting in much more
efficient utilization of power.Aerial bunched cable system is specially suited in
limited space conditions like densely populated areas where laying of underground
cables is impossible or extremely expensive.In India with economic reforms and gradual
opening of economy to the global system, the Power sector has become one of the
key areas of attention of everybody concerned.