It has been five years since Trafo Power Solutions supplied two dry-type transformers to Alphamin’s Bisie tin mine in the Democratic Republic of Congo. Those transformers have performed well – and another three modular substations equipped with dry-type transformers are now on order, soon to be transported to the site, to serve the mine’s expansion.
“This latest order is testament to the standard of performance of our dry-type transformers at Bisie mine over the past five years,” says David Claassen, Managing Director of Trafo Power Solutions. “There were a number of challenges we had to consider in our design for the transformers, not least of which is a very arduous section of the road on the journey to the mine.”
Located in the remote Walikale Territory of DRC, the mine is about 180 km northwest of Goma, and more than 30 km from the national route linking Walikale with Kisangani. Like the initial order, the three 3 000 kVA, 400 V/11 kV substations will be supplied in standard six-metre containers to facilitate transportation. However, specialised steel bracing is required to ensure the modular substations withstand the difficult road conditions, especially over the last part the journey.
“These conditions make the road almost impassable by any vehicle other than a six-wheeled Unimog,” says Claassen. “There is intense vibration and tilting of the cargo on the trailers, so we design the substations and the bracing with this in mind.”
He notes the mine’s foresight in specifying the first dry-type transformers. At that time, the technology was relatively new and the standard practice was to use oil-filled transformers for this type of application. As well as the logistics of transporting equipment to the site, the equatorial climate and frequent lightning strikes were considered in selecting the modular substation solution with dry-type transformers.
“The region where the mine is located is ranked in the top five most vulnerable to lightning strikes, so there is a high risk of damage to equipment related to electrical surge,” Claassen says. “We therefore designed robust surge protection solutions on both the medium voltage and low voltage sides of the substations, and for the transformers.”
Trafo Power Solutions is supplying another three modular substations, with dry-type transformers, to the Bisie tin mine in the DRC.
Given the warm and humid climate, Trafo Power Solutions also designed a fully redundant N+2 cooling system for the transformers. This means each transformer is cooled by two fans, with another two fans on standby. Additionally, dry-type transformers have the advantage that the MV winding is completely cast in resin, so it is well protected and highly resistant to humidity.
For more information visit: www.trafo.co.za
