Trafo Power Solutions recently supplied specialised transformers for the Tippler 3 project at the iron ore load-out station at the port of Saldanha Bay, in South Africa, as part of an upgrade Transnet is currently conducting at the facility.
The construction of a third tippler at the Saldanha Bay port is to sustain iron ore export volumes of 60 Mt/y when the existing tipplers are refurbished in the future. It will integrate with the rail system bringing ore via the 860 km line from mines in the Northern Cape of the country.
Key aspects of the new infrastructure comprise the 285 t 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 are also part of Transnet’s upgrade project, according to Trafo.
Factory-acceptance testing of the dry-type transformers were completed in December 2019, according to Trafo Power Solutions Managing Director, David Claassen, with delivery to site taking place in February.
Trafo Power Solutions’ contract was for the design, supply and commissioning of five dry-type transformers. There are two 1,000 kVA units and a 3,150 kVA unit, both stepping down from 11 kV to 400 V, the company said. The other two units are 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 the 3CR12 grade of stainless steel, according to Trafo. The enclosures are also IP33-rated to ensure a high level of ingress protection against moisture and dust.
“The enclosure design also incorporates cable boxes and Type C totally enclosed plug-in bushings for the terminations,” Claassen says. “This provides a boot covering, which is touch-potential safe, and also 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, according to the company. 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.”
The K-factor is a measure of a transformer’s ability to withstand the heating effects of non-sinusoidal harmonic currents created by electronic equipment, Trafo explained. “The higher the K-factor, the greater the harmonic heating effects,” the company said.
As dry-type transformers are cooled without the use of oil, these units will receive forced ventilation when a pre-set temperature is reached. This ventilation is provided from a row of fans which Trafo designed to be bolted below the location of the transformers.
Designed locally in South Africa by Trafo Power Solutions, these dry-type transformers are manufactured in Italy by strategic partners TMC Transformers, which focus on cast resin transformer technology. All products are routinely factory-tested according to IEC standards, but type-testing and special testing can also be conducted, according to the company.
“The standard applicable to dry-type power transformers is IEC 60076-11,” Claassen says. “TMC’s advanced laboratory facilities allow us to conduct the full range of tests in-house, in accordance with what these standards and whatever other requirements are designated by the customer.”
At Saldanha, Trafo is also responsible for building auxiliary protection and control panels, which it locates remotely from the transformers. These include temperature control sensors that communicate with the port’s broader control and monitoring network.