5 March 2013 - Actom Electrical Machines has completed manufacture of all the customised low voltage motors required for the air-cooled condenser (ACC) units at Eskom’s new Medupi and Kusile coal-fired power stations.  

The company was awarded the ACC units LV motors contract for Kusile power station near Delmas in Mpumalanga in August 2009 by Johannesburg-based SPX (DB Thermal), the ACC subcontractor to Alstom Power, the main contractor for the turbines of the new power station. This followed the award in November 2008 of the ACC units LV motors contract for Medupi power station near Lephalale in Limpopo Province by GEA Aircooled System, the ACC subcontractor to Alstom Power in that instance.

The Medupi and Kusile ACC motors contracts together are worth close to R100 million. The contract, for design, manufacture and supply of a total of 384 x 250 kW four-pole squirrel cage induction motors, along with soft-starters, for the ACC units at Kusile was completed well ahead of schedule, while the Medupi contract, comprising a total of 384 x 225 kW four-pole squirrel cage induction motors, has been completed on schedule.

Says Tony Teixeira, Actom Electrical Machines’ general manager, “In tackling the Kusile contract we benefitted greatly from the experience we gained on the Medupi contract, but it involved some unique challenges of its own.”

The earlier contract involved designing and developing motors that incorporated additional equipment without compromising their efficiency. To ensure that this was achieved the company first produced a prototype motor, which it test ran to ensure that the contract’s stringent performance specifications were met before it went ahead with production of the final product.

“The motors for Kusile follow the same design concept as developed for Medupi’s ACC units. However the soft-starters required for the Kusile motors necessitated a similar preliminary test exercise, for which we developed a simulation process to test the soft starter-motor-load combination to ensure that it worked at optimum efficiency,” Teixeira explains.  

“We designed and assembled a special item of equipment to simulate the actual site conditions. These prototype tests were witnessed and approved by SPX, Alstom and Eskom.”