• CRADLE TO GRAVE
Supplied by Trafo Power Solutions
Each mini-substation is equipped with a control system that will allow the protection functions to be monitored remotely .
“ The units are designed to be as compact as possible ,” he explains . “ While many will be used for surface infrastructure , the design had to ensure that they could be used underground , where space is limited .”
The underground environment is governed by stringent safety regulations and standards , making the dry-type transformer an ideal choice . This technology uses air rather than oil to cool the windings , making it safer with less risk of fire , explosion or environmental contamination through leakage . The windings in dry-type transformers are also encapsulated with cast resin , protecting them against humidity levels up to 95 %.
Undertaking both the electrical and mechanical design , Trafo Power Solutions has ensured a limited footprint through the use of air-to-air heat exchangers . Air is channelled through the transformer windings and flows over the aluminium tubes of the heat exchanger , while a fan blows air through the tubes to cool the air on their outer surface .
“ The substation design also includes arc protection , which will shut the unit down in the event of an arc occurring – before any further damage can be caused ,” he says . Each mini-substation is equipped with a control system that will allow the protection functions to be monitored remotely .
The contract was conducted through a leading South African engineering , procurement and construction management ( EPCM ) firm , and Trafo Power Solutions ensured that all units were delivered by the end of 2023 .
“ Our early engagement with the EPCM was important on this project , as it allowed our team to understand the project requirements and develop a cost-effective solution ,” Claassen says . During this process , all documentation was strictly managed within an online system , including designs , specifications and test certificates – to which the EPCM and end-client had easy access . In this way , designs could be uploaded , shared and signed off using this platform , further streamlining activities for the fast pace of the project .
“ The ring main units are fully motorised and controlled externally by remote pendant switching ,” he says . “ This enhances safety and ease of management , so that personnel seldom have to open the panel doors which requires the necessary safety equipment and protocols .”
The transformers are rated for Class H insulation – for temperatures up to 180 degrees – while the dual-voltage boards are sizeable for a relatively complex voltage distribution system on each minisubstation .
“ The detailed design and variety of solutions within the complete contract package really highlights the technical capability of the Trafo Power Solutions team ,” says Claassen . “ This can be seen in the mini-substation from the medium voltage side and its control and protection functionality , through to the low voltage distribution and the customised transformer design for these applications .”
He emphasises that the standard attributes of dry-type transformers allow them to operate reliably with very little maintenance . With air rather than oil for cooling , for instance , they do not require any regular oil testing or oil changing .
The robust nature of dry-type transformers makes them well-suited for mining applications , whether surface or underground . Claassen notes that Trafo Power Solutions ’ extensive experience in Africa reflects that dry-type technology is becoming more popular in the mining sector . The reasons for this trend include their inherent safety , their reliability and their ability to operate without much maintenance . •
Source : Supplied by Trafo Power Solutions
This technology uses air rather than oil to cool the windings , making it safer with less risk of fire , explosion or environmental contamination through leakage .
34 • African Mining • March 2024 www . africanmining . co . za