Electrical Cables and Overhead Conductor

Listing ID #3188571

With the great support of our in-house storage facility, we are capable to undertake bulk and urgent requirements of the customers. This facility helps us in keeping the stock away from dust, moisture, rain and others damaging factors. Purchasers can order our goods in wholesale, as we ensure year around obtainability. In addition, we have dependable shipping network to ensure timely distribution.

Indian utilities presently have over head distribution systems employing mainly bare over head lines. Metallic screened ABC cables are used where transitions through trees, proximity to buildings or strong winds which lead to conductor clashing can cause safety and reliability issues.

The enhanced safety and reliability benefits of ABC cable comes at a cost which is several times the constructional cost of bare over head lines and therefore inhibits the utility engineer to employ the ABC system except where unacceptably high fault records with bare overhead lines justify the additional expense.

A typical 11kV ABC or 33kV ABC cable comprises of three single phase cables twisted around a steel/aluminium alloy messenger (a wire that supports the three cables). Each single phase cable comprises of a round, compacted stranded aluminium conductor with a semi conductive screen extrusion over it followed by XLPE insulation (3.6mm for 11kV and 8.8mm for 33kV) with a bonded semi-conductive layer over the insulation, copper tape shielding and an outer PVC/PE outer sheath. This construction very well conveys to the reader, the reasons for the very high costs of ABC as compared to bare over head lines. The limited deployment of 11/33 kV ABC cables on cost considerations, leads to loss of revenue, inconvenience to consumers and cases of electrocution in some cases.

An alternative approach to enhance the safety and reliability of bare over head lines while minimizing the additional cost is the use of Covered Conductor Systems.

COVERED CONDUCTORS :

• The conductors in a Covered Conductor System are made of stranded, alloyed aluminium chosen to achieve maximum transmission capacity with optimum resistance to conductor breakage and also to resist galvanic corrosion associated with ACSR lines.
• The conductor is waterblocked throughout by injected cross-linked compound so that moisture cannot penetrate. The conductor is covered with a cross linked weather resistant polymer, to aid ultra-violet radiation resistance and achieve long term life. The maximum operating temperature of the conductor insulation is 80ºC but short circuit temperatures may reach 200ºC. The thickness of the insulation layer is 2.3 mm.
• The working practices associated with building conventional bare over head lines can easily be applied to covered conductor installations. The covered conductor can be drawn through rollers and guided so that the covering is not damaged. A cable pulling device has been created to stop the covering sliding over the greased conductor. Working at the top of a pole is much easier. The cross arms are considerably lighter than steel angle iron arms of almost three times the length, so that lifting and spanning work is more ergonomic with no great stretching or rubbing against the other phase wires or use of special tooling.
• Experience with covered conductors in Sweden and Finland indicate that failure frequency has been reduced up to 75%. Fewer faults result in less wear of circuit breakers, connection equipment and above all far greater availability of supply to the consumer.
• The total investment costs are some 0-20% higher than for bare over head lines depending on routing, climatic conditions etc., but as far as the overall economy of the installation is concerned, one must also take into account improved operating reliability, safety aspects and long term economic effects of the reduction in down time frequency and duration.