One of the world’s highest grade known tin deposits is being developed in the Democratic Republic of Congo, and dry-type transformers from specialist supplier Trafo Power Solutions are now integral to powering this effort.

Two 3000 kVA, 400 V / 11 kV cast resin transformers – housed in six-metre containers – were recently delivered to Alphamin Resources’ remote Bisie mine site in North Kivu province. They will step up the supply from the operation’s diesel-powered generator plant from 400 V to 11 kV. Trafo Power Solutions also supplied two 100 kVA, 400 V / 400 V Dyn11 dry-type lighting transformers for outdoor applications.

Bisie is located about 180 km north‑west of Goma, in the Walikale Territory – some 60 km from the town of Walikale and 32 km from the national route linking Walikale with Kisangani.

“The mine’s remote position, and the difficult access road to the mining operation, made it essential for us to custom-design the substation and transformers to withstand the rough journey,” says Trafo Power Solutions managing director David Claassen.

According to Claassen, the complete solution was manufactured in a fast track project that took only 12 weeks. This included the in-house design of ventilation and airflow systems to deal with the extreme heat and humidity levels of over 90% ,as well as lighting and small power equipment.

He highlights the suitability of dry-type transformers to the climatic conditions at the mine, especially their ability to remain cool with only minimal movement of air across the windings. Where necessary, extremely high ambient temperatures may require the employment of forced air options in the design.

“The cast resin design of dry-type transformers improves their efficiency and hence their heat losses, so cooling requirements are reduced,” he says. “Their efficiency also means they consume less energy, which in this application saves on diesel costs.”

Among the advantages of dry-type transformers is that they require almost no maintenance and can last up to 25 years without much attention. Oil-filled transformers, on the other hand, need regular maintenance and sampling of oil if they are to operate safely and consistently.

In a remote location like Bisie mine, this advantage delivers particular benefits to the user. 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.