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Low-loss high-capacity overhead conductors

What are low-loss high-capacity overhead conductors?

Electricity generated in power plants is transmitted to homes and factories via power cables. Overhead conductors suspended between pylons transmit high-capacity ultrahigh voltage power. During the transmission, however, not all electricity is transmitted, but some is lost mainly due to electrical resistance of the cable.*1 Amid the efforts to save energy and realize a low-carbon society, there are growing needs in the industry for low-loss high-capacity overhead conductors to reduce the losses and enable efficient and stable transmission. To respond to such needs, Sumitomo Electric developed low-loss high-capacity overhead conductors.

Electrical energy lost as heat due to the resistance of transmission line, which is particularly large in long-haul transmission such as overhead power lines.

Features of this product

Cross-sectional view of the low-loss high-capacity conductor
Cross-sectional view of the low-loss high-capacity conductor

In overhead conductors, aluminum cable steel reinforced (ACSR), in which aluminum cables are twisted around a steel core, is widely used. Our low-loss high-capacity conductors adopted a steel core material that is 1.3 times as strong compared to the conventional materials, reducing the core diameter, while increasing the aluminum ratio by tightly placing trapezoidal aluminum wires without gap around the core. As a result, while maintaining the similar outer diameters and tensile strength compared to conventional wires, our new conductor reduced electrical resistance and thus transmission loss by 20-25% compared to conventional conductors.

Increased efficiency in power transmission enables low-loss transmission of necessary electricity to demand areas, reducing the volume of power generation and thus CO2 emissions during generation.

In addition, our conductor adopting heat-resistant aluminum*2 has current capacity of about twice that of the conventional wire, sufficiently retaining the back-up capacity in emergency and contributing to the improvement of power grid reliability.

Aluminum that can be continuously used at a temperature of 150°C (while standard aluminum can be used at a temperature of 90°C). Increased current volume raises heat generation, but heat-resistant aluminum is able to transmit high current.
Interview with the engineers in charge
Power Projects Business Division
Kyota Hoshikawa
Kyota Hoshikawa

Where are they used?

This product is used in ultrahigh voltage power transmission lines between power plants to suburban substations and between substations, playing an important role in power supply to urban areas. In October last year, the product was adopted in the backbone transmission network connecting cities in Sri Lanka.

Electricity is one of the critical, indispensable infrastructures in our life. The needs to enhance and improve the efficiency of power transmission network are growing in the world. Drawing on the technologies we have accumulated, Sumitomo Electric will continue contributing to the stable supply of electricity within and outside of Japan.

Overhead Transmission Line Division
Tomohiro Kagami
Tomohiro Kagami

What difficulties did you face in developing this product?

This product increases the occupancy ratio of the aluminum component in conductors by using trapezoidal-shaped aluminum without gaps. The construction inevitably made the cable surface smoother than conventional ones, making it potentially susceptible to wind resistance. To eliminate the need to enforce pylons, our customers demanded us to maintain the wind resistance of the new cable similar to the conventional ones.

In conventional techniques, to reduce wind resistance, dented cable surface was mainly used. However, the same method decreases the volume of aluminum, and is thus less effective in reducing transmission loss. Our product secured similar aluminum volume by creating small steps on the surface, achieving both low loss and low wind resistance during transmission.

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