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:: M&C Installs Stator Coil Connections in Zambia
Marthinusen & Coutts (M&C), a South African based repairer of rotating electrical equipment and a division of Actom, has successfully installed four mill motors at a copper mine in north-west Zambia. The massive electric motors, with diameters of 12.2m and 8.5m respectively and with each stator quadrant weighing approximately 100t, are the largest M&C has helped install to date and may be the largest in Africa.
M&C’s scope of work comprised the installation of stator quadrant windings on the four mill motors, which were manufactured by Siemens in Germany. The four motors are gearless mill drives (GMDs), also known as wrap-around motors, and include two 26MW ball mill motors and two 28MW SAG mill motors. Among the challenges on this project were the remote location of the mine, which is located approximately 400km north-east of Kitwe, and working during a heavy rainy season while also trying to meet an incredibly tight deadline.
M&C 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 44kg.
Meeting the given deadlines was imperative, and M&C’s provision of the appropriate technical skill sets with a team of competent technicians as well as sound on-site organisation ensured the success of the project. A fully equipped 6.1m 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.
Richard Botton, divisional CEO at Marthinusen & Coutts, said: “We’re well versed in carrying out site work in remote locations on the African continent. 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 GMDs, 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."
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