EXCLUSIVE FOR MODERN MINING
POWER SUPPLY & EFFICIENCY FEATURE JUNE 2022
While Africa’s mines are still predominantly users of oil-coiled transformers, the situation is changing fast with dry-type transformers making strong inroads into the mining market due to their inherent safety features and the fact that they are virtually maintenance free. In addition, they can easily be transported to the remote sites which so often characterise the African mining scene.
“We’re noticing a big uptake of our dry-type transformers by mining customers,” says David Claassen, Managing Director of Johannesburg-based Trafo Power Solutions, which specialises in providing high-quality dry-type transformers in the 50 kVA to 25 MVA range. “Our units offer the same efficiency as their oil-cooled competitors, are very economic to run and are extremely safe, which, of course, is an absolutely key requirement on mines. The case for choosing them over the oil-filled alternative is very compelling.”
Claassen, who has been in the electrical business for 20 years, founded Trafo Power Solutions in 2017. “I was convinced that there was a huge potential for dry-type transformers in Africa and I established the company with the goal of eventually becoming the leading supplier of these units in the African region,” he recalls. “Our growth since then has been typical of what you would expect to see from a start-up company with a great idea and sales have grown continuously – sometimes almost exponentially – in the five or so years we’ve been in business.”
Trafo Power Solutions sources its transformers from TMC Transformers in Italy, a global leader in the field, and has the exclusive rights to sell and support TMC’s products in sub-Saharan Africa (although it sometimes supplies even further afield). “Our partnership with TMC has been vital to our success,” Claassen observes. “They’re a company noted for innovation and they share our vision of what can be achieved in the African market. They specialise in customised designs and are eager to take on any technical challenge.”
While the transformers are fully imported, the enclosures that are often required to house them are produced locally with Trafo Power Solutions handling the designs and specialist suppliers undertaking the fabrication. Units can be standalone or integrated into mini or modular sub-stations, with Trafo Power Solutions supplying the entire package.
Elaborating on the safety features of dry-type transformers, Claassen says that the key point to understand is that they are cooled through natural ventilation in contrast to conventional transformers which have windings that are immersed in oil. “Oil-cooled transformers generally work well but there is no denying that the oil is both a fire and an environmental hazard, and these are both important considerations in the mining industry,” Claassen observes.
“Fires can arise internally in an oil-type transformer as a result of a fault such as a short circuit and then the oil acts as a fuel, with the result that the fire destroys the transformer – sometimes explosively – and possibly spreads to surrounding infrastructure. A fire can also arise externally and then spread to the transformer, again with dire results. In both cases, noxious fumes can be emitted from the transformer. None of these scenarios is possible with dry-type transformers, which makes them particularly appropriate for enclosed spaces such as underground mines and for all hazardous areas.”
Claassen adds that Trafo Power Solutions’ dry-type transformers are categorised as F1 in terms of international fire resistance ratings and are manufactured from materials that are flame retardant and self-extinguishing.
Apart from the fire risk, oil leaks are always a possibility with oil-type transformers, particularly as they age, which means that a bund is often required to contain any spillage. Moreover, the oil has to be checked at regular intervals to ensure that it is free of contamination. By contrast, Trafo Power Solution’s dry-type transformers normally require just a once-a-year check-up which can be completed in two hours.
A major selling point for Trafo Power Solutions is that its transformers can be customised to meet customers’ requirements. “To give an example, we’re currently working on a contract to supply a South African underground gold mine with two large transformers,” Claassen says. “We’ve had to design them with space and mass constraints in mind as they will be taken down to the working area in a cage via a vertical shaft. Tight specifications of this type are frequently encountered with underground mines and, in conjunction with TMC, we are always able to provide a solution.”
Another advantage of Trafo Power Solutions’ dry-type transformers is that they are generally more transportable than their oil-filled counterparts. “This is the result of their rigid construction which allows them to withstand the vibrations of road travel, which in many parts of African can be quite severe due to the poor condition of roads,” notes Claassen.
The transportability of Trafo Power Solutions’ units was well illustrated several years ago when the company supplied two 3 000 kVA, 400 V/11 kV transformers and two smaller lighting transformers to Alphamin’s new Bisie tin mine in the DRC’s North Kivu Province, arguably one of the most remote mine sites in Africa. Trafo Power Solutions designed the transformers and associated sub-station to withstand the long journey by road. The solution provided – which included the design of ventilation and airflow systems to counter the extreme humidity and heat which can be experienced at the site – was manufactured in just 12 weeks and delivered to the mine within the agreed timeframe.
In another successful contract, Trafo Power Solutions supplied four dry-type units to a mine in Sierra Leone. The challenge here was to provide transformers able to move along with mobile process plant over rough terrain. The transformers proved more than capable of handling the tough conditions – so much so, in fact, that the mine followed up with a second order for six more units.
The ability of Trafo Power Solutions’ transformers to work under exacting climatic conditions was highlighted recently when it supplied a 3 000 kVA transformer to a gold project in Kyrgyzstan located at an altitude of 4 020 m above sea level on a site where temperatures can go as low as minus 40 deg C.
According to Claassen, the range of conditions in which Trafo Power Solutions’ transformers can be deployed is continually widening and he cites the case of recent installation in Mexico in which dry-type units supplied by TMC have been rated at IP68, the very top of the international IP rating scale, which is a measure of resistance to water and solids ingress. “Basically, this means that the transformers can be totally submerged in water without ill effect,” he says.
Looking at Trafo Power Solutions’ strategy moving ahead, Claassen says that it will be a case of “more of the same” from the company. “We believe in staying close to our customers so that we can understand their needs,” he says. “This approach has served us well and will remain at the heart of our strategy. We’re optimistic about prospects and see particular growth in mining, which is experiencing a strong upturn at the moment. We’ve built up a significant population of machines on African mines and we’re confident that we will continue to expand our market share.”
