As South Africa’s many thousands of oil-cooled mini substations reach the end of their operating lives, there is scope to replace them with a safer and more economical option, according to Trafo Power Solutions managing director David Claassen.

“These mini substations are located all along our urban streets, in shopping centres and around industrial areas – in close proximity to growing numbers of people,” says Claassen. “As municipalities struggle to maintain these properly, they pose an increasing safety risk and become more expensive to service and repair as they get older.”

He points out that oil-cooled transformers require regular testing and maintenance, including monitoring and replacement of oil at regular intervals to ensure effective cooling of the unit. Without this maintenance, the risk of failure or even explosion is raised.

“Dry-type transformers do not contain oil, being cooled by air moving over the components,” he says. “This is one of the factors behind the significantly lower maintenance required by dry-type transformers, which of course translates into substantial cost savings over time.”

The absence of oil makes dry-type transformers considerably safer, he explains, as indicated by these units’ F1 fire rating. This means that they are resistant to flammability, are flame retardant and generate no harmful emissions.

Having no oil as a coolant also makes dry-type transformers less risky to the environment. The risk of oil spilling from an oil-cooled transformer – which can lead to the contamination of land and water – requires the construction of a bund wall. The dry-type option needs little of this kind of additional infrastructure, and so is more cost-effective to install.

“Trafo Power Solutions has worked extensively with developers of high-traffic infrastructure like shopping centres, ensuring the highest level of safety in mini substations located in high-density areas,” he says. “We are well positioned to supply public utilities with the same benefits.”

He notes that municipalities’ financial resources to service and maintain substations are often severely stretched, so it makes sense for them to seek more economical alternatives. Dry-type transformers are almost maintenance-free, he explains, taking a considerable load off the owners’ maintenance duties.

“We custom-design our solutions for dry-type miniature substations to meet customers’ exacting requirements,” says Claassen. “This includes any variation of medium voltage (MV) and low voltage (LV) needs and specific switchgear as well as customised control and protection options.”

Trafo Power Solutions supplies miniature substations from 200kVA to 2500kVA – ranging from 3,3kV to 33kV on the MV side, and from 400V to 1000V on the LV side. These substations are rated up to IP65 ingress protection.