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When Swakop Uranium’s Husab mine near Swakopmund in Namibia needed mobile pit transformers, Zest WEG Group’s Integrated Solutions Division was able to not only custom-design a fit-for-purpose solution, but also to adapt its design to suit new requirements.

“Having initially provided four skid-mounted pit transformers to Husab back in 2014, we were contracted to provide a further unit more recently, but the solution needed to be adapted to the changed conditions,” says Alastair Gerrard, Zest WEG Group Integrated Solutions Division executive. “The first units were designed to be located in the pit, and dragged short distances to follow the drills rigs and electric shovels. The new unit, however, needed to offer the capability of improved manoeuvrability across longer distances within the operational area.”

In some cases, transporting a skid-mounted containerised transformer greater distances outside of the mining area meant employing a crane and low-bed, and the mine was looking for a more efficient and cost effective solution. To optimise the mobility of these units, Zest WEG Group Integrated Solutions Division designed a removable gooseneck system on the front of the unit, and a removable bogey at the back.

“In adapting to the units’ new operational requirements, our optimised design took into account modifications that could also be applied to the existing units,” says Sollie Herbst, general manager at Zest WEG Group Integrated Solutions Division. “The adapted mobile transformer can now be easily moved as a truck and trailer configuration to various operational areas, and when positioned the gooseneck can be removed and the landing legs extended.”

Gerrard emphasises that these solutions are not off-the-shelf; rather, everything they design is fit-for-purpose and engineered for a specific application. Such a custom design now makes it possible to retrofit the existing units currently on site, as and when necessary.

“Our custom focus is one of our key values – and this demands that we fully understand the site conditions and the operational requirements of our customers,” he says. “Our design experience and technical capacity allowed us not only to design a mobile pit solution for this customer, but to adapt that design to promote the ease of the system’s relocation. This means interfacing closely with our customers to get a detailed picture of exactly how they need to use the product they are requesting from us, and what they need to gain out of the system.”

The mobile transformer was designed upward from a robust steel base-frame with a modified 12 metre shipping container on top. The mine was provided with an interface point to receive 33 kV from the mains reticulation, stepping down with a 5 MVA transformer to 6,6 kV, which was fed out to the equipment.

Keeping within the dimensions of the container to facilitate mobility, the engineering design includes a switchgear chamber for the 33 kV supply, a transformer chamber and another switchgear chamber for the 6,6 kV output. The container also protects the electrical equipment from debris such as fly rock in areas close to drilling and blasting activities. Provision for ventilation has been provided in the container, and the transformer chamber roof is removable so as to allow for easier access during maintenance.

The new design also includes both 33 kV and 6.6 kV quick couplers, making for safe and fast connection of the power supply into and out of the unit. Being mobile within harsh mining conditions also required a level of robustness to be designed into the engineered solution.

“To protect the components – during relocation – we reinforced the switchgear to limit the movement of these panels,” says Gerrard. “We also took into consideration the seismic rating of the sensitive components.

The selection of switchgear was another key design consideration to ensure minimum unplanned downtime in this production driven environment. For this reason, fixed pattern switchgear, which offers better performance in mobile applications was installed as it also requires minimal maintenance.

When selecting components for any power solution, Zest WEG Group Integrated Solutions Division makes use of those brands that are well supported by the OEM, and those that preferably have a service facility close to where the customer’s equipment is being used.

“Spare parts availability and product support is vital to contribute towards efficient operations, especially where the equipment incorporates advanced technology that requires specialist skills,” says Herbst.

Zest WEG Group’s Integrated Solutions Division provides custom-engineered solutions in the power generation, electrical infrastructure and mobile solutions market space.