Marthinusen & Coutts, a leading South African based repairer of rotating electrical equipment and a division of Actom, has again demonstrated its ability to undertake complex on-site engineering assignments in remote locations in Africa with the successful installation of four mill motors at a copper mine in north-west Zambia. The massive electric motors, with diameters of 40 and 28 foot respectively and with each stator quadrant weighing approximately 100 tons, are the largest M&C has helped install to date and probably the largest in Africa.
Marthinusen & Coutts’ scope of work comprised the installation of stator quadrant windings on the four mill motors, which were manufactured by Siemens, Germany. The four motors are Gearless Mill Drives, also known as wrap-around motors, and include two 26 MW Ball mill motors and two 28 MW SAG mill motors. Among the challenges on this project were the remote location of the mine, approximately 400 km north-east of Kitwe, and working during a heavy rainy season while also trying to meet an incredibly tight deadline. Known for its flexibility and responsiveness Marthinusen & Coutts was able, at short notice, to mobilise a team of highly skilled technicians to undertake the winding of the 16 quadrant joints on the motors. Each joint on the motor has seven large (uninsulated overhang) ‘flexible’ coils, which are used to help contend with the connecting of the stator coils at the quadrant interfaces, while the balance of the coils are normal resin-rich set diamond type coils, each weighing 44 kg.
Meeting the given deadlines was imperative and provision by Marthinusen & Coutts of the appropriate technical skills sets with a team of competent technicians as well as sound on-site organisation ensured the success of the project. A fully equipped 20 foot container, equipped with the correct tooling and test instruments, was prepared and dispatched to site. Each SAG mill motor was completed in less than 25 days, while the ball mill motors were completed in less than 23 days. “We’re well versed in carrying out site work in remote locations on the African continent,” Richard Botton Marthinusen & Coutts Divisional CEO, says. “We fully understand the various work practices and cultures of the local people and we’re able to draw on a well-established network to deal with complicated cross border protocols. Marthinusen & Coutts owns and manages a fully functional service shop in Kitwe, Zambia, with technicians on call to support our customers in the region.
“Marthinusen & Coutts has become an expert in gearless mill drives, winding termination and testing of motor segments. Our track record in the GMD arena includes the installation of two wraparound electric motors at Lumwana Copper Mine in the north-west of Zambia a few years ago and, more recently, the completion of an on-site rotor and stator rewind of a 70MVA synchronous condenser in the DRC. “The latest contract underlines Marthinusen & Coutts’ flexibility in carrying out complex and difficult on-site installations and services within a short lead time and completing these jobs to world class standards. We’re one of only a handful of companies worldwide capable of offering these services.”