High efficiency transformers: Showering economic and environmental benefits

January 6, 2016 2:04 am0 commentsViews: 204

By KN Hemant Kumar

High effi economic benefi reduced greenhouse gas emissions, they ciency transformers create ts for society. Besides improve reliability and give a potentially longer service life by bringing down temperature rises through energy efficiency (EE) improvements. India has, by now, adopted the international IEC standards and also introduced star labelling for select categories of transformers.

According to the Leonardo Energy – Transformers Report 2005, the global transmission and distribution network losses will lead to global economic loss of more than US$61 billion annually and annual greenhouse gas emissions of more than 700 million tons. In general, it is estimated that one-third of network losses occur in transformers and of these transformer losses, 70 per cent occur in distribution transformers. The report estimates that the total electricity lost on utility networks around the world in 2005 was approximately 1,279 TWh, and of that, distribution transformers consumed 298.4 TWh.

Most power losses occur in the transformer core made up of magnetic steel or in the electrical coils or windings of either aluminium or Copper.
Copper reduces load loss, because it is a more efficient conductor. By reducing load loss, Copper wound transformers helps increase profit margins of power distribution companies. Besides, the smaller size of copper transformers saves core steel as well as structural elements, including the tank, oil, cooling equipment and other accessories. And copper being stronger than aluminium, the former withstands stresses better than aluminium, thus, extending the transformer’s life and reducing lifecycle maintenance costs. The market size for transformers in 2013 was at 266,000 MVA in India and has seen an annual growth of 17% year on year. The target for capacity addition during the 12th Five-Year Plan is 88,000 MW.

Potential for improvement
According to World Bank statistics, energy losses throughout the world’s electrical distribution networks amount to 1683 TWh. They vary from country to country between 3.7% and 26.7% of the electricity use, which implies that there is a large potential for improvement.

After lines, distribution transformers are the second largest loss-making component in electricity networks. Transformers are relatively easy to replace, certainly in comparison with lines or cables, and their efficiency can fairly easily be classified, labelled and standardised. Moreover, modern technology exists to reduce energy losses by up to 80%.

The largest power transformers have efficiencies at full load of 99. 75%. Distribution transformers are smaller, less efficient and more lightly loaded. Transformers in urban distribution (typically 250 – 1000 kVa) may lose 1-2 % of energy transformed as heat. For smaller transformers in rural areas (50 – 100 kVa) efficiency in operation can be as low as 95%. In a constantly developing environment, energy consumption is an issue to be urgently dealt with. For instance, in EU, over 4 million distribution transformers have been installed ie 1 unit for every 80 citizens. It takes 7 – 8 of the largest nuclear power stations to compensate the energy losses in these transformers. All the wind turbine capacity installed in 2000 covers only 10% of these losses in distribution transformers.

Replacing all distribution transformers by energy efficiency types could save 200 TWh a year, equivalent to 130 million tonnes of CO2 emissions – an advantage large large enough to justify the effort.
Clearly energy efficiency in power distribution transformers is a key factor in sustainable electrification.

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