Underground mines in southern, central, and west Africa have been seeing the safety benefits of dry-type transformers from Johannesburg-based Trafo Power Solutions.

According to Trafo Power Solutions managing director David Claassen, this clientele even includes collieries, where the strictest safety regulations apply with regard to fire hazards.

“The high risk of fire in underground coal mining environments has led to a high demand for dry-type transformers,” says Claassen. “Among the fire risks that coal mines face are transformer short-circuits as well as fires reaching the transformer.”

He notes that dry-type transformer technology is rated Class F1 in terms of fire protection, ensuring that transformers supplied by Trafo Power Solutions are flame-retardant.

“Oil-cooled transformers, on the other hand, are a fire risk due to the oil they contain to cool the windings,” he says. “The risk is heightened by the harsh operating conditions in which many transformers must function on mines.”

These transformers also require regular attention and maintenance. Oil samples must be taken at prescribed intervals, and these must be tested at a laboratory with the appropriate accreditation. Testing must be conducted to ensure that oil purity is within bounds, and to check for gas levels and pressure build-up in the oil tank.

“This maintenance can present challenges and added costs if the equipment is located on a remote mine far from a source of expertise and the right equipment,” says Claassen. “With dry-type transformers, it is really only the temperature that requires monitoring. The equipment comprises limited componentry, so generally requires servicing only twice a year.”

He highlights that these regular inspections are brief and simple, taking just a couple of hours. Key aspects to be checked are the physical termination connections – which must be tightened to the right torque – and any dust that has gathered around the core and windings must be cleaned away.

Trafo Power Solutions has in recent years supplied dry-type transformers – along with ancillary power equipment such as low and medium voltage switchgear – to mines in South Africa, Mozambique, Zambia, the Democratic Republic of Congo (DRC), Ghana and Sierra Leone. In addition to coal, there are gold and base metal producers included in this clientele.