Electricity and Control June 2020

TRANSFORMERS, SUBSTATIONS + CABLES

oil or other bio-based fluids for cooling that they offer the particular advantage of safety, ensuring a minimal risk of fire, a hazard to which traditional oil-based transformers are vulnerable if not properly maintained. Dry-type transformers and their enclosures are also required to meet fire protection class F1 standards. The further advantage of being environmentally friendly also derives from the transformers using no oil – obviating any risk of an oil spill or contamination in high-hygiene production areas or public buildings. In addition, dry-type transformers offer the major advantage of requiring minimal maintenance. “Maybe three hours maintenance work every six months,” says Claassen, “they are close to maintenance-free.” Where traditional oil-based transformers require regular monitoring and specialised analysis of the oil, and the apparatus, dry-type transformers eliminate this cost. Claassen acknowledges that some of the new technologies on the market, using bio-based fluids with a higher burning point, do reduce the risk of transformer fires, but the risk of oil leaks, for example, still applies. Leaders in specialised design Trafo Power Solutions is the exclusive partner of TMC Transformers for sub-Saharan Africa. Claassen points out that TMC is one of the biggest manufacturers of cast resin transformers in the world. With operations in Italy and Switzerland, TMC has the capacity and the expertise to produce transformers at scale and in specialised application-specific designs, with an extensive design inventory on which it can draw. “The partnership works because to a large extent we share the same business philosophy. While TMC does produce a standard range of dry-type transformers it has the expertise to develop specialised designs for particular applications. At Trafo, we recognise that each project is different, with different requirements in a different environment, to serve a different application, handling specific loads. And this is our focus, in supplying specialised transformers to meet the needs of each project. “Within the partnershipwe are responsible for all the projects in sub-Saharan Africa, handling the application engineering, project management, the logistics of supplying equipment to often remote locations and the onsite installations. “One of the key advantages we bring to the partnership is our extensive experience of working on the African continent. Varying climates, different locations, local protocols and networks, all play a part and Africa is not the same as Europe. TMC values this understanding and our commitment to providing the specialised equipment to meet the needs of each application.” Trafo Power Solutions supplies dry-type cast resin transformers up to 25 MVA, 52 kV and VPI transformers up to 5 MVA, 36 kV, miniature substations up to 1 000 kVA, 22 kV, as well as customised modular substations including all LV and MV electrical equipment.

At a glance ■  Trafo Power Solutions supplies specialised, non-standard transformers to meet specific requirements for each project, across various industry sectors. ■  Compared to conventional oil-based transformers, dry-type transformers provide safety, environmental and maintenance advantages. ■  In its partnership withTMC Transformers,Trafo is responsible for all projects in sub-Saharan Africa.

Specialised dry-type transformers for Saldanha Bay port Trafo Power Solutions earlier this year delivered dry-type transformers for the Transnet upgrade of its port facility at Saldanha Bay in the Western Cape. The company is supplying specialised transformers for the Tippler 3 project at the iron ore load-out station. Factory-acceptance testing was completed in December 2019 and the transformers were delivered to site in February. The construction of a third tippler at the Saldanha Bay port is being undertaken to sustain iron ore export volumes of 60 million tonnes per year when, in future, the existing tipplers are refurbished. It will integrate with the rail system bringing ore via the 860 km line from mines in the Northern Cape. Key aspects of the new infrastructure comprise the 285 tonne tippler itself, a loading vault below ground and a conveyor tunnel. New buildings, service roads, bridges, railway lines, conveyors, lighting and bulk electrical supply infrastructure also form part of the upgrade project. Trafo Power Solutions’ contract was for the design, supply and commissioning of five dry-type transformers: two 1 000 kVA units and a 3 150 kVA unit, each stepping down from 11 kV to 400 V; and two other units, 3 500 kVA and 4 500 kVA capacity respectively, taking 11 kV to 3.3 kV. To resist the corrosive sea air, all the transformer enclosures were manufactured from 3CR12 grade stainless steel. The enclosures are also IP33-rated to ensure a high level of ingress protection against moisture and dust. Claassen highlights: “The enclosure design incorporates cable boxes and Type C, totally enclosed plug-in bushings for the terminations. This provides a boot covering which is touch-potential safe, and provides for efficient plug-and-play installation.” This is a significant improvement on the regular lug and bolt copper connection, which would just be shrouded by a heat- shrunk material. The special terminations also facilitate easier maintenance or removal. “The units will provide the medium-voltage supply for the Tippler 3 project and its associated infrastructure, including equipment like conveyors,” he says. “All the transformers will be supplying non-linear load to a certain extent, so they have been designed with a K-factor of four.”

Electricity + Control JUNE 2020

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