Electricity and Control August 2020

ENERGY MANAGEMENT + THE INDUSTRIAL ENVIRONMENT : PRODUCTS + SERVICES

Customised transformers for renewable energy

Class H specifications. This gives them the capacity to withstand temperatures of up to 180°C. Another aspect to be considered in renewable energy applications is the non-linear load that inverters add to the mix. The transformers need to be designed with a K-Factor much higher than that used for standard distri- bution type loads, and with the addition of an electrostat- ic shield between the primary and secondary windings, to eliminate potentially damaging leakage currents. Claassen notes that dry-type transformers are being specified increasingly, instead of conventional oil trans- formers, for demanding applications such as renewable energy plants. “With an oil-cooled unit, the temperature fluctuation arising from the rapid and regular energising and de- energising cycles brings its own challenges,” he says. “In particular, it causes more gases to be emitted within the transformer tank, which leads to a variety of problems.” The cast resin material used in Trafo’s dry-type trans- formers meets the specifications of the International Electrotechnical Commission (IEC) for fire class F1. The units therefore present minimal fire risk, allowing them to be used indoors safely, and without environmental pro- tection like bund walls which are required to contain po- tential oil spills where oil transformers are used. Claassen adds that dry-type distribution transform- ers are fast becoming a more suitable alternative to oil transformers, especially in the distribution power range between 50 kVA size and 10 MVA. He highlights too that Trafo Power Solutions is able to supply dry-type trans- formers up to a power rating of 25 MVA. has a business volume of about US$10 billion (based on reported annual revenues for fiscal years 2017-2019 (ABB’s Power Grids Division)), and ABB holds the balance. Toshikazu Nishino, Executive Vice President of Hitachi, is the Chairman of the new entity and Claudio Facchin the CEO. Hitachi ABB Power Grids is headquartered in Zurich, Switzerland. The current management team will ensure business continuity. Nishino said, “Hitachi’s leading digital technologies merged with world-class power grid solutions will help us to play an active role in the global transformation and decarbonisation of energy systems for a sustainable energy future. Intelligent solutions for a more dynamic grid will also contribute to the UN’s Sustainable Development Goal 7 of ‘affordable, reliable and sustainable energy for all’.” The joint venture brings together two highly respected companies to create a new global power leader. The alliance with Hitachi will facilitate expansion opportunities for the new entity in areas such as mobility, smart cities, industry, ener- gy storage and data centres, as well as providing financial For more information contact Trafo Power Solutions. Visit: www.trafo.co.za

A focus on application engineering enables Trafo Power Solutions to supply customised dry-type transformers for a range of sectors including renewable energy. “We begin at the proposal stage by engaging closely with the customer about the exact application and elec- trical load,” says David Claassen, Managing Director of Trafo Power Solutions. “This means every project gets its own transformer design, so that it is fit for purpose.” In renewable energy applications, there are some very specific demands that need to be accommodated.

A solar power generating plant, for example, presents a situation in which a transformer will be energised from zero to 100% on a daily basis. “This leads to wide fluctuations in tem- perature inside the transformer which, in turn, causes the resin around the wind- ings to expand and contract considera- bly,” Claassen explains. The windings in dry-type transformers are insulated in a cast resin or epoxy material, rather than oil, and rely on air movement for cooling. “Such fluctuations could result in the resin cracking, so the design must spec- ify the appropriate class of insulation to

A multi-winding cast resin transformer which includes an electrostatic shield, designed for complex load conditions associated with renewable energy applications.

cope with these conditions,” he says. “We can design our windings for either a Class F or a Class H insulation. In addition, the mixture of the resin is specially formulat- ed to accommodate the duty cycle specific to renewable energy applications.” The standard design – using Class F – can deal with temperatures up to 155°C. However, for many of Trafo Power Solutions’ low voltage and high voltage installa- tions around Africa, the design includes a resin mix to

New power entity established

In accordance with the agreement signed on 17 December 2018, Hitachi Ltd. and ABB Ltd. have announced the completion of all required procedures as planned and the formation of Hitachi ABB Power Grids Ltd. on 1 July 2020. Hitachi has an 80.1% stake in this new joint venture entity, which

Hitachi ABB Power Grids will focus on smart solutions for dynamic grids to provide affordable, reliable and clean energy.

18 Electricity + Control AUGUST 2020