MechChem Africa September 2017

⎪ Power generation, sustainable energy and energy management ⎪

Containerised power solution drives Mali mill Shaw Controls, a Zest WEG Group company, recently completed its contract to supply a containerised electrical solution to a gold mine in Mali, West Africa. This project made use of a WEG MVW01 VSD with a 6.6 kV output, a 36-pulse rectifier and a corresponding phase shift transformer on the input.

S haw Controls, a Zest WEG Group company, reports the successful completion of its contract to supply a containerised electrical solution to a gold mine inWest Africa. KirkMoss, medium voltage manager at Shaw Controls, says the solution will supply power to drive a mill on this new mine. “Containerised electrical so- lutions are becoming increasingly popular as these allow for speed of installation and are a particularlycost-effectiveoption formineand plants operating in Africa,” Moss says. The custom engineered sub-station com- prises a medium voltage (MV) WEG Variable Speed Drive (VSD) and a dry type phase shift transformer drivinga2000kW, 6-pole, 6.6kV squirrel cageWEGelectricmotor. TheVSD is housed in the container while the oil-cooled transformer is housed just outside of it to facilitate heat dissipation. Moss says that Shaw Controls has an established reputation for engineering and manufacturingqualitybespoke containerised solutions at its Johannesburg facility. The extensive facility of over 12000m 2 ismanned by a team of skilled technical personnel and having the whole construction take place in one facilitymakes it easier for customers todo all quality and functional checks in one place. This solution underwent testing at Shaw Controls prior to being dispatched to site. “What is particularly interesting about this solution is that it has been specifically engineered for the particular application and utilises specialised software for frozen charge protection,” Moss says. The software, which interfaces with the VSD, allows the objective detection of a fro- zen charge condition bymaking use of torque measurements already being monitored by the VSD. “With the addition of an encoder fitted to theelectricmotor, wearenowable tomonitor mill angle. Andwith the torqueandanglemea- surements it is possible to detect if cascading has occurred within the mill,” he explains. Another innovative featureof this solution is the supply of a Human Machine Interface (HMI) in the form of an interactive touch screen, which has been configured to allow different levels of access. This has been done

inauser-friendlymannertoensureeaseofuse andalsoallows simple access to relevant data. Moss says that the ability to extract the most relevant data and provide this in an intuitive and simplified format allows both operational and service personnel tomonitor the requisite parameters. This project made use of a WEG MVW01 VSD. The input solution makes use of a 36-pulse rectifier and a corresponding phase shift transformer. Moss explains that this combination was selected as the best option to minimise harmonics. TheWEGMVW01 VSD range is available in 3.3 kV and 6.6 kV versions. This is a neutral point clamped (NPC) topology andmakes use of 6.5 kV IGBTs. These VSDs are engineered with few components, translating into high efficiencies and optimal reliability. Also available is the WEG MVW3000 which is available in 3.3 kV and 6.6 kV, and more recently, in an 11 kV version. This is a

Kirk Moss, medium voltage manager at Shaw Controls, inside the containerised solution that will supply power to drive a mill on a mine in Mali. cascaded H-bridge (CHB) topology, which makes use of low voltage IGBTs. Shaw Controls’ product line includes MV switchgear and LV withdrawable MCCs – lo- cally manufactured products that are inde- pendently certified in accordance with the IEC62271-200andIEC61439-1/2standards. According to IEC specifications, LV covers applications up to 690 V, while the MV range is from 1 kV up to 52 kV. All products carry ISO9001 accreditation fromBureau Veritas. Being part of the ZestWEGGroup also al- lows ShawControls access to the substantial technical databaseandengineering resources of parent company WEG Brazil. q

The WEG MVW01 medium voltage 6.6 kV Variable Speed Drive (VSD) makes use of a 36-pulse rectifier and a corresponding phase shift transformer. Moss explains that this combination was selected as the best option to minimise harmonics.

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