Electrical Power & Protection

Dry-type transformers go mainstream

December 2019 Electrical Power & Protection

The uptake of dry-type transformers in South Africa is now well beyond ‘niche’ applications, with local specialist Trafo Power Solutions installing a range of sizes across various sectors. “In recent months, we have been involved in projects with small 50 kVA low voltage lighting transformers, right up to 4,5 MVA medium voltage customised units,” says David Claassen, managing director of Trafo Power Solutions. “These have been installed in healthcare facilities, commercial buildings, educational institutions, mines and data centres, as well as at solar energy plants.”

Among its recent contracts, the company has supplied a number of lighting transformers. It has also provided outdoor instrument transformers to facilitate measurement of voltage on overhead lines. These cast-resin voltage transformers (VTs) typically have 33 kV, 22 kV and 11 kV primaries with 110 V secondaries with between 50 VA and 500 VA burden.

In the mining sector, a recent contract was the installation of 200 kVA dry-type transformers. This is often a corrosive environment in terms of water and dust, so a high ingress protection (IP) rating was applied. Claassen adds that a range of materials and paint can also be specified by the customer to further withstand corrosion.

Data centres are a fast growing aspect of the country’s digital economy, and Trafo Power Solutions is supporting this segment with its cast-resin transformers. It recently delivered and cold-commissioned two 2 MVA units for a data centre in Cape Town.

“These facilities obviously require the highest levels of reliability and protection from their electrical and electronic networks,” says Claasen. “The windings and core of our units were designed for a K factor of 13, given the high non-linear load. An electrostatic shield was also installed, along with surge protection of the highest order.”

He notes that there was substantial time pressure to complete the contract, but flexibility and responsiveness at Trafo Power Solutions ensured on-time delivery.

At three small-scale solar plants, Trafo Power Solutions is providing three 800 kVA transformers which will step up power from 400 V to 22 kV. These applications involve a solar inverter for the 100% non-linear load, as well as an electrostatic shield between the primary and secondary windings.

Claassen emphasises that the business prides itself on the level of application engineering for each customer’s specific requirements. “We understand what we are supplying and the risks faced by the customer and we design the solution accordingly,” he concludes. “Industry is certainly showing their faith that dry-type transformers can be applied in a growing range of applications.”

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