Trafo said the Alphamin Resources mine in the Walikale Territory of the DRC's North Kivu province recently took delivery of two 3,000kVA, 400V/11kV cast resin transformers housed in 6m containers.

The site's diesel-powered generator plant will be boosted from 400V to 11kV, and Trafo said it also supplied two 100kVA, 400V/400V Dyn11 dry-type lighting transformers for outdoor applications.

Managing director David Claassen said it designed the mine's order custom, from the substation to transformers, to withstand the harsh journey into the mine's remote location. The fast-tracked manufacturing took 12 weeks, including in-house design of ventilation and airflow systems to manage the region's extreme heat and humidity levels of over 90%, as well as lighting and small power equipment.

"The cast resin design of dry-type transformers improves their efficiency and hence their heat losses, so cooling requirements are reduced," he said of how suitable the dry-type transformers were to the mine's conditions. "Their efficiency also means they consume less energy, which in this application saves on diesel costs."

He added that they have an ability to remain cool with only minimal movement of air across the windings; where necessary, the mine's extremely high ambient temperatures could require the use of the design's forced air options.

Trafo also pointed out that, while oil-filled transformers require regular maintenance and oil sampling for safe, consistent operation, dry-type transformers require nearly no maintenance and have a lifespan of up to 25 years.

"In a remote location like Bisie mine, this advantage delivers particular benefits to the user," Claassen said. "Dry-type transformers can also be installed indoors, without the need for their own civils infrastructure such as bund walls and structures - as there is no oil posing safety or environmental risks."

Bisie's cold commissioning was expected to commence this month, with the completion of the gravity concentration building's construction to follow in next year's March quarter, along with the operation's tailings storage facility. First plant ore is expected to be realised in March 2019.