Specially engineered mini substations designed and manufactured to meet space limitations and operational demands were recently delivered by Trafo Power Solutions to an underground copper mine in Zambia.

Trafo Power Solutions MD David Claassen revealed that the order for 17 mini substations included 800 kVA units and 1 000 kVA units. He explained that the project required precise engineering to address shaft cage size constraints and a confined area underground.

“The first important consideration was the size of the shaft cage used to transport equipment and material underground,” Claassen said. “We understood what the limitations were and carefully designed a solution that would allow easy loading and transportation in the cage to the levels where the units would be deployed.”

The smaller dimensions of the units, however, brought a challenge related to the cooling of the transformers. A vital consideration in these designs was to ensure that there was still sufficient airflow to cool the transformers, he explains. As the designer reduces the dimensions of the equipment, the airflow generally becomes more restricted.

“We were therefore careful to understand exactly what the ambient conditions would be and then to ensure that the flow of air would match the requirements of the transformers’ particular specifications,” he said.

The absence of flammable liquid, such as oil, in the transformers of dry-type units makes them a preferred option, from a fire protection and safety perspective.

Claassen added that the dimensions of the mini substations allow them to be easily loaded onto rail cars and moved from one underground location to another – as required by the advancing of the mining face.

“The dry-type transformer offers a very robust option for these demanding applications,” Claassen says. “There is no risk of oil leakage as a result of damage, for instance.”

The mini substations were fully manufactured in South Africa and the customer will be given in-country aftersales support for the units.