Modern Mining November 2016

PRODUCT News

SA company repairs condenser for DRC facility & Coutts by an international OEM who is a global leader in electrical engineering.

Marthinusen & Coutts, a division of ACTOM, is well advanced with the reassembly and recommissioning of a very large synchro- nous condenser in the DRC. The repair contract was awarded to Marthinusen & Coutts early last year by an international electricity equipment com- pany currently engaged in an upgrade project on the hydroelectric power supply system for the DRC’s power utility, SNEL. Richard Botton, Divisional Chief Executive at Marthinusen & Coutts, says the most significant aspect of this order is the fact that it was placed on Marthinusen

The repair work undertaken on the rotor of the 70 MVA condenser involved con- ducting a thorough inspection of the rotor forging and bare rotor by Marthinusen & Coutts’ on-site repair team. This was fol- lowed by the refurbishment of the bearings, and testing and fitting new salient poles that had been manufactured earlier by the international company to replace the origi- nal salient poles. This company had also earlier rewound the stator as part of its por- tion of the repair work on the condenser. Marthinusen & Coutts is also responsi- ble for the balancing of the rotor. The rotor weighs 90 tons and runs at 750 rpm in a compromised installation from a founda- tion stiffness point of view. “Significantly, we are employing the services of arguably the top balancing specialist in South Africa who will carry out the dynamic balancing on-site,” Botton says. In line with Marthinusen & Coutts’ pol- icy of investing in the latest technology, the company recently acquired a Bently Nevada ADRE 408 portable vibration and balancing system which will be used for this task. Skilled technical personnel from Marthinusen & Coutts’centre of excellence in Cleveland, Johannesburgwere deployed to site and the condenser is scheduled for recommissioning at the end of 2016. Marthinusen & Coutts, tel (+27 11) 607-1700 includes a 2 000 kW, 6 pole, 6,6 kV squirrel cage WEG electric motor, a medium volt- age WEG variable speed drive (VSD) and a dry type phase shift transformer. The VSD and transformer will be housed in a custom engineered and manufactured sub-station. The sub-station will be manufactured and fully tested at ZestWEG Group’s sub-station and panel facility in Johannesburg. “Another very important advantage to the customer is that in dealing with a single OEM, the fully completed electrical solution will be shipped to site as a plug-and-play solution,” Claassen says. The equipment is scheduled for deliv- ery to site in the first quarter of 2017 and Zest WEG Group will be responsible for all interfacing between the VSD and upstream MV switchgear, output isolation and the complete control and protection system including frozen charge protection. Kirsten Larkan, Zest WEG Group Africa, tel (+27 11) 723-6000

Botton says that Marthinusen & Coutts had previously repaired two of the Kolwezi power station condensers in earlier con- tracts a few years ago. “Part of the repair work on the third condenser had been done when the international company commissioned us to complete the job; this based on our experience and our success- ful complete refurbishment of the other two condensers,” he says. The synchronous condensers are critical components of the DC/AC converter sta-

tion in Kolwezi in the DRC, which converts the DC power transmit- ted on a 1 700 km transmission line from a converter at the Inga hydroelectric power station on the Congo River. The power from the Kolwezi converter feeds the energy intensive Copperbelt in Katanga Province. The synchronous condens- ers supply the necessary reactive power, which cannot be transmit- ted via the DC transmission line or provided by the converter station. The inertia of the rotating assem- bly of each condenser provides the necessary energy to stabilise the power system in the region, which aids the overall stability of the grid.

Marthinusen & Coutts Lead Field Services Technician Wynand Willemse applies the finishing touches to one of the SNEL 70 MVA synchronous condensers completely refurbished almost from the ground up.

Energy efficient plug-and-play solution for Yanfolila mill Access to an OEM that can cover the full electrical scope of supply for mill appli- cations is a major advantage and this is exactly what secured the Zest WEG Group the contract for the supply of an energy efficient solution to drive the mill at the Yanfolila gold project in Mali. extensive expertise in electrical solutions for mill circuits but also its access to a com- prehensive range of quality products.

Zest WEG Group is the South African subsidiary of leading Brazilian motor and controls manufacturer WEG. The group’s product line-up includes electric motors, vibrator motors, variable speed drives, transformers, MCCs, containerised substa- tions, mini-substations and diesel gensets, as well as electrical and instrumenta- tion construction and project execution services. Claassen says that being in this enviable position, ZestWEG Group is able to exercise absolute control over the packaged solu- tion including shortening lead times and offering customers the flexibility inmeeting exact application requirements. The electrical solution for Yanfolila

Yanfolila is being developed by Hummingbird Resources as a low cost, high grade, open-pit mining operation. Its first gold production is targeted for 2017. Following close collaboration with the mill Original Equipment Manufacturer (OEM), Zest WEG Group provided an optimum solution which will meet the per- formance parameters of the milling circuit while ensuring cost efficient operation. David Claassen, Executive at Zest WEG Group, says this is a good example of where the group is able to leverage not only its

44  MODERN MINING  November 2016