Johannesburg based Trafo Power Solutions have designed a dry-type transformer that can function at minus 40⁰C, at an altitude comparable to Mount Everest’s base camp.
The custom-engineered unit has been designed and supplied to a gold mine expansion project in Kyrgyzstan. The company has provided a 3,000kVA transformer with a primary 6,3kV and a secondary 400V specification, which will operate at 4,020 metres above sea level.
David Claassen, managing director of Trafo Power Solutions ,said the altitude presented a challenge to the design in terms of cooling. “Most large electrical equipment is rated for 1,000 metres or below, so we had to de-rate this unit to account for the altitude. The higher the location, the less efficient the cooling – and the temperature range on site is between minus 40°C and plus 25⁰C.”
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The eight tonne outdoor transformer has a specially designed enclosure to keep out snow, dust and moisture, while also extracting heat. Claassen noted a risk of condensation when the transformer is turned off under these conditions.
“We therefore built into our design a control system for automatically heating the enclosure when the transformer stops operating for any reason. The heaters will then, of course, be turned off again once the transformer resumes operation,” Claasen explained.
Under the demanding environmental conditions, the enclosure was coated with a corrosion resistant C5 paint plan. The design also included a neutral earthing resistor with special surge protection elements.
“A dry-type transformer is well-suited to these cold conditions as there is no fluid involved in the cooling process, and it is fairly straightforward to provide the necessary heating and cooling as required. There is also very little maintenance required, which is a great advantage in a remote location like this,” said Claasen.
With travel restricted by the COVID-19 pandemic, the customer could remotely witness the factory acceptance test conducted at TMC’s IEC-approved facility in Italy, which allows all routine and special testing to be done in-house.
“The online factory acceptance test uses communication technology and cameras around the test bay, including cameras focussed on the technician performing the test. This allows the customer to check in detail all aspects of the specifications,” said Claasen.