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Fast execution on chrome mine substation

9 October 2012 – A turnkey contract, awarded by Control Alliance of Pretoria, the engineering, procurement and construction management (EPCM) contractor acting on behalf of chrome mining and processing company Tharisa Minerals, was given to Actom Power Systems. This was for a 60 MVA 88 kV/11 kV substation to supply power to Tharisa Minerals’s recently erected platinum-chrome concentrator inBuffelspoort- Marikana, North West Province, South Africa.

Ranesh Sharma, Actom Power Systemscontracts manager, says, “We were given eight months to do the job. A project of this magnitude and complexity normally requires a year at the very least to carry out.” The R19million project, which got under way in October 2011, was completed on schedule at the end of May 2012.

To speed up the process Control Alliance and Actom Power Systems agreed to divide the project into two contracts – a supply contract and a construction/installation contract. “For the supply contract we identified all the long-lead items and ordered them immediately to ensure delivery as quickly as possible and to allow us more time for the design process.

“The first contract was concluded towards the end of February 2012. The equipment procured was then in effect free-issued from the first contract to the second, which had already got under way in November with the civil work. A further procedure we followed by mutual agreement was having weekly progress report meetings, instead of the normal monthly meetings, which also helped to speed things up.

“The only equipment available at the start were the three 20 MVA power transformers, supplied by a manufacturer in China, which were free-issued to us for installation. We subcontracted manufacture and supply of all the other equipment required to the relevant Actom companies,” Sharma says.

These were high voltage equipment for circuit breakers, current transformers, voltage transformers, isolators and earth switches, distribution transformers for auxiliary transformers, protection and control for protection equipment and static power for battery chargers.

“A complication arose due to the failure of a third party protection relay that had to be outsourced from another supplier in Europe. However, this was returned and repaired in time to meet the deadline. The unfamiliar voltage regulators supplied with the Chinese power transformers also necessitated some adaptations on our part to make them work,” Sharma says.