Improving the efficiency of the electrical transmission grid

September 21st, 2012, Published in Articles: Energize

For over one-hundred years, electricity has been delivered to consumers using bare overhead conductors that were made up of conductive aluminum strands commonly wrapped around a core that consisted of steel wires.  As demand for electricity grew and new sources of generation were brought on line, many transmission and distribution lines became thermally constrained. The relatively high coefficient of thermal expansion (“CTE”) of the steel core and aluminum strands, allows the conductor to sag as its temperature rises. CTC Cable Corporation (Now CTC GLOBAL), of Irvine, California, USA, began developing the patented ACCC conductor in 2002.

As the project evolved, CTC developed a hybrid carbon and glass fiber core that resisted degradation from UV, chemical, thermal, and cyclic load fatigue. The ACCC conductor, which offers approximately twice the capacity of conventional conductors, is now being used to increase the capacity of existing transmission corridors without the requirement for structural modifications.  The ACCC conductor’s greater strength and improved thermal stability can also enable longer spans on fewer or shorter structures on new transmission lines which serves to reduce upfront capital costs. The ACCC conductor’s increased aluminum content also helps reduce line losses by 30 to 40% under equal load conditions. A reduction in line losses offers huge advantages.

Not only can more electricity be delivered from existing sources of generation as demand increases, under normal load conditions, fuel consumption is reduced. Conversely, when used to link a renewable source of generation, the ACCC conductor can help deliver more power for less capital cost. It’s often been said that it’s much cheaper to save a “NegaWatt” than it is to produce a MegaWatt.  In 2007, American Electric Power (AEP) reported that by simply reconductoring an existing 20 km line with ACCC conductor, they reduced losses by 0,9 MW and also reduced overall system losses by an additional 0,2 MW, for a total improvement of
1,1 MW.  To date, American Electric Power has completed eight ACCC conductor installations. Worldwide, over 14 000 km of ACCC conductor has been installed at 215 project sites.

Contact Craig Robertson, ARB Electrical Wholesalers, Tel 031 910-0200, craigr@arbhold.co.za

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