Modern Mining April 2020

electrical wave harmonics at play. In applications such as datacentres and electrical locomotives which are erratic loads causing harmonics, we design the transformer accordingly. We adapt the casting, the size of the coils and the resin, among others. “At a solar plant, for instance, the transformer is energised from zero to 100% daily. This means tem- perature fluctuations that cause contraction and expansion of the resin, which, in turn, could crack the resin if it isn’t adapted to cope with fluctuating temperatures.” Trafo’s windings can be designed for both class F and class H insulation, the former being the standard design, where the transformer must withstand tem- peratures of up to 155. “We mix our resin to class H, which means it can withstand temperatures up to 180. We supply class H windings for low and high-voltage to many of our installations on the continent.” He says dry-type transformers typically have elec- trical efficiencies between 98,5% and 99,5% The loss of around 1%, he says is generated by the core and the windings and expressed in temperature. “In Europe, they subscribe to the governmental Energy Efficiency Directive which specifies minimum efficiencies. We adhere to this directive although it isn’t legislated in this country.” 

has the highest incidence of lightning strikes in the world, and very high humidity and temperature – right up our alley.” Customisation Trafo Power Solutions has an exclusive agreement with TMC Transformers of Italy to supply to sub- Sahara Africa. “TMC has over 40 years’ experience in cast resin transformers, with a large, modern facility, nine winding machines and a casting plant that can han- dle eight coils at a time. We take care of the whole process, from the proposal to sales, application engi- neering and after-sales.” Should a fault occur in an installed product in Africa, a Trafo engineer would visit the site to assess the situation. If this initial step proves unsuccessful, the company will access TMC’s design and coop- erate with the OEM to ensure that the problem is solved. Trafo considers many environmental conditions when determining the most suitable transformer for the application. “On the electrical side, we look at the load the transformer will supply. Standard distribution loads such as houses or buildings don’t require much cus- tomisation of the transformer, unlike when there are

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