Transnet’s upgrade of its port facility at Saldanha Bay will include dry-type transformers that are specially manufactured to suit the conditions at the project.

To resist the corrosive sea air, all the transformer enclosures will be manufactured from 3CR12 grade stainless steel. The enclosures are also to be IP33-rated to ensure a high level of ingress protection against moisture and dust.

Trafo Power Solutions is supplying the specialised transformers for the Tippler 3 project at the iron-ore load-out station. The enclosure design incorporates cable boxes and Type C totally enclosed plug-in bushings for the terminations, which provide a boot covering that is touch-potential safe and also provides for plug-and-play installation, explains the company.

The construction of a third tippler at the Saldanha Bay port is to sustain iron-ore export volumes of 60-million tons a year when the existing tipplers are refurbished in future. It will integrate with the rail system bringing ore by way of the 860 km line from mines in the Northern Cape. 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.

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 other two units are 3 500 kVA and 4 500 kVA capacity respectively, taking 11 kV to 3.3 kV.

The company asserts that this is a significant improvement to the regular lug and bolt copper connection, which would ordinarily be shrouded by heat-shrunk material. The special terminations also aim to facilitate easier maintenance or removal.

The units will provide the medium-voltage supply for the Tippler 3 project and its associated infrastructure, including equipment such as conveyors. The transformers have been designed with a K-factor of four, where 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. The higher the K-factor, the greater the harmonic heating effects.

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 designed to be bolted below the location of the transformers.

Designed locally by Trafo Power Solutions, these dry-type transformers are manufactured in Italy by strategic partners TMC Transformers, that specialise in cast resin transformer technology. According to the company, all products are routinely factory-tested according to IEC standards, but type-testing and special testing can also be conducted.  

The company is also responsible for building auxiliary protection and control panels at Saldanha, which it locates remotely from the transformers. These include temperature control sensors that communicate with the port’s broader control and monitoring network.