MATERIALS
Aluminium conductors conform to IS:8130(Class-II)
Standard high tensile galvanized steel messenger wire conforms to IS:398
Alternatively Aluminum Alloy messenger wire conforms to IS:398
XLPE and HDPE insulation of power conductors specify IS:7098 and IS:6474 respectively.
STRINGING:
No difficulty is envisaged during stringing of Aerial Bunched Cables in the conventional method but care shall be taken that insulated conductors do not get damaged during installation. Dragging the ABC on the ground is to be avoided. Tension to be applied during stringing shall be 25% of the breaking load of the messenger wires. This will allow line to have sag within specified limit of 1.5% of the span at the lowest ambient temperature.
JOINTING:
While mid-span jointing permissible for LT ABC system by conventional technique, our recommendation will be to draw the line in such a way as to bring the joints at the supports. Mid - span joining is not at all recommended in the case of HT lines our recommendation is for outdoor type HV terminations only. Under unavoidable circumstances, line tapping at the support points may be allowed through suitably designed clamp connectors /PG clamps. The semi conducting screen continuity shall be maintained at all joints as far as possible to avoid fluctuations during system disturbances. The 3-phase screens may be shorted and earthed through suitable non-liner surge arrestor. Attempting to make a tap off from power conductors in the region where catenary is under tension in not recommended.
APPLICATION:
Aerial Bunched Cables can be conveniently used:
As replacement of bare lines in Rural Areas, in woods and in other localities & narrows streets where the space limited.
As replacement of bare lines where reliability of supply is of prime importance.
As replacement of bare lines where high degree of stability of supply voltage is of importance.
In hilly terrains where cost of erection of overhead lines or under ground cable becomes very high.
As reinforcement of existing system without increasing voltage.
For temporary supplies.
Advantages:
Less fault rate on account of good protection against line and ground fault by high winds or falling trees or birds especially in hilly areas & forests as encountered in rural distribution networks.
High insulation resistance to earth in all seasons and polluted atmospheres. Negligible leakage currents and low losses.
Multiple circuits of Power and Telephone cables could be strung in the same set of poles or any other supports like walls etc.
Better adaptability to run concurrently with existing overhead bare conductor system without any interference.
High capacitance and low inductance leading to low impedance of lines.
Lower voltage drop, higher current capacities. VIS-Ã?-VIS Better Voltage Regulation.
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