ABB has won an order worth $107m (£68m) from SNEL (Société Nationale d’Électricité), the national power company in the Democratic Republic of Congo, to upgrade key technology on one of the world’s longest electricity transmission systems.

The contract was signed in the fourth quarter of 2009.

ABB will refurbish the stations that convert alternating current to direct current and back on the 560MW Inga-Kolwezi power transmission link.

The 1,700km system was originally built by ABB in 1982.

The link uses HVDC (high-voltage direct current) technology to transmit power from the Inga Falls hydropower station on the Congo River to the mining district of Katanga in the south east of the country. It also enables excess power to be exported to the Southern African Power Pool countries.

ABB will be responsible for system engineering, including design, supply and installation of new thyristor valves, high-voltage apparatus and ABB’s MACH2 control and protection system.

The project is scheduled for delivery in 2013.