While the supplier did not indicate the name of the customer, it did say the coal miner's operation is in the Limpopo province. It took the dimensions beforehand so it could fit the units into the space available at the site.

"This required one of the transformers - a specialised 3900kVA unit - to be copper-wound to achieve a smaller footprint suitable to the space constraints without compromising the technical performance," MD David Claassen said.

He added that, with 11kV capacity on the primary windings, the first transformer included four separate secondary windings for the respective outputs of 1810V, 1515V, 1360V and 1210V.

"Being located outdoors on a coal mine, the transformer had to be well protected from fine dust and moisture, requiring a specially designed IP54 enclosure," Claassen noted.

"At the same time, the transformer's large size meant substantial heat loss, which needed to be extracted from the enclosure. The design, therefore, included an air-to-air heat exchanger to recycle cool air in a closed loop."

The second transformer unit of the paid was for indoor application, a 1600kVA version that steps down from 11kV to 550V. It met the electrical and dimensional requirements of the placement, as well as its control and protection system, by working alongside transformer repair company Koratech Services.

"Underground mining often presents space constraints which have to be considered in the design of the transformer or the miniature substation," Claassen said. "With our expertise and our strategic partnership with leading Italy-based manufacturer TMC Transformers, we can readily cater for these conditions."

Trafo said both transformers were ordered during the tight Level 5 Covid-19 lockdown in South Africa. Thanks to its collaborative work with its partner TMC, it was able to design, build and supply the transformers during the disruptions, even though for a time, similar restrictions were in place in Italy.