In most power plants across Africa, clients prefer to install modular-type solutions, also known as containerised solutions or e-houses, and dry-type transformers fit “perfectly” within this scope, says transformer supplier and specialist Trafo Power Solutions MD David Claassen.

The preference for installing modular-type solutions has been on “quite an upward trend” over the past decade in terms of standby power generation, he adds, noting that this has translated into an increased use of transformers.

Transformers, which are often used in factories, by mining companies on their mines, and in corporate buildings and hospitals, consist of copper or aluminium windings that need to be insulated and cooled down.

However, with the entry of dry-type transformers to the African market over the past ten years coinciding with the increased use of modularised substations, Claassen notes that Trafo also designs and customises its transformers according to client specifications and requirements.

Owing to the absence of oil as a coolant in dry-type transformers, they are suitable for use in confined spaces, without requiring the conventional infrastructure to protect the environment from possible oil spillages or workers from potential fire hazards, says Claassen.

Modular and mobile substations, which are often converted into sea containers or e-houses, are growing in popularity for applications across Africa because they can be fully prepared under workshop conditions, reducing the work required on site.

Trafo’s complete solutions are available for mining, retrofitting or replacing existing oil transformers, mobile solutions, applications in data centres, variable-speed drive applications or even standard distribution loads.

The company can also mobilise service support to any of the sites it supplies.

Environmental Benefit

Oil transformers have, historically, been the norm in the South African market, with oil proving a highly effective insulator and cooling agent.

However, Claassen says there has been a global trend towards using environment-friendly equipment, particularly from a safety improvement perspective.

The fossil-fuel-dependent transformers present a safety risk, as a result of its high flammability, with the transformers at risk of catching fire either from internal electrical faults or external influences. Using oil, moreover, produces gas emissions and requires regular maintenance, including oil sample analysis to ensure operational consistency and safety.

In contrast, the dry-type transformers, also used in the modularised solutions, are completely flame-retardant, emissions-free and use resin and vacuum- pressure impregnation to insulate the windings and air as a cooling agent.

This, Claassen avers, makes the transformer safer to use, while reducing maintenance, resulting in cost and time saving for end-users.

“A dry-type transformer is a safer alternative that uses only air to cool, and there is no oil involved. It’s more suited to be installed indoors; however, we have designed and installed dry type transformers for outdoor applications with an ingress protection rating up to IP68,” he notes, adding that when used and designed correctly for the application, end-users can expect to see upwards of a 30-year life span.

Trafo’s transformers comply with the European eco-design directive, which delineates minimum standards for energy losses from transformers. This allows for a lower total cost of ownership than less efficient models.

Further, end-users will benefit from the reduced energy consumption of these dry-type transformers owing to the higher efficiency of the cast resin design, available in class F or class H insulation classes, which consequently results in lower electricity bills and reduced heat loss, says Claassen.

The need to be adequately prepared for the lack of electricity bought on by load-shedding, has somewhat influenced the drive for renewable energy, which has become a more attractive option for consumers, which is further encouraged by the dramatic price increases in electricity in South Africa, and across several African economies.

Renewable-energy methods also use transformers to step-up generation voltages.

Electrical engineering products manufacturer TMC Transformers, based in Switzerland and Italy, works closely with Trafo Power Solutions to develop several dry-type transformers for renewable- energy markets such as photovoltaic, wind and biomass co-generation.

Impregnated transformers and inductors are installed in many inverter cubicles, which are then used in the conversion of wind or solar energy.

Project History

Trafo recently delivered transformers and other electrical upgrades for a global beer maker’s expanded facility, in Gauteng.

The client was also looking for a partner that would interface with the suppliers of a variety of electrical equipment. Trafo interacted with the client’s Europe-based engineering team and with local electrical contractors.

The transformers – a 1 250 kVA and a 1 600 kVA unit, both with 11 kV to 400 V capacity, as well as a 2 000 kVA unit for an 11 kV to a 690 V application – were designed, supplied and commissioned under tight deadlines.

The company also recently completed a contract involving the design, supply and installation of two dry-type transformers, as part of a significant upgrade at an Mpumalanga coal mine.

These are housed in specialised IP42-rated enclosures, and the units were specified by a design house on behalf of the client. The transformers were also equipped with the necessary earth-fault and surge protection, as well as vibration pads.

Trafo has also completed projects in the agriculture, and food and beverage sectors, and even in diesel generation, in various African countries.