Transformers are among the most efficient machines ever designed by mankind, and are usually built of copper or aluminum. As copper has conductivity almost twice that of aluminum, it is often preferred in transformer construction. The largest power transformers have efficiencies at full load of 99.75%. Distribution copper-based transformers are smaller, less efficient and more lightly loaded. Transformers in urban distribution (typically 250-1,000kVa) may lose 1-2% of energy transformed as heat. For smaller transformers in rural areas (50-100kVa), efficiency in operation can be as low as 95% Most of the distribution transformers installed by the State Electricity Boards use high levels of energy which results in huge losses. A large number of Distribution Transformers used in India, particularly in smaller ratings such as 25KVA, 63KVA, 100KVA (11KV/415V, 3 phase) use conventional materials and methods of manufacture, resulting in very high losses. The failure rate of these transformers is very high, around 16% (in Govt. SEBs), which is not favorably comparable to international norms of 1 to 2%. Further the life of these conventional transformers is very low (6-8 years). The higher failure rate also adds to the already high Transmission & Distribution (T&D) losses in the power distribution network of SEBs.

Why Choose Copper

The advantages of using Copper in transformer windings:

  • Inherent low loss material
  • Special skills not needed during jointing and termination (significant percentage of transformer failure can be attributed to defective joints and termination)
  • Copper scores over Aluminium in several respects such as conductivity, resistance, thermal conductivity, better withstanding capability during short circuit, etc.
  • Easy availability and competitive pricing favours “Copper” usage.

Transforming the Transformer

Distribution Transformers (DTs) are key assets for any distribution network. Their reliable and efficient operation can result in long-term benefits for the Indian power distribution utilities. The DT failure rate in India is high in the order of 12-15% (in State Utilities), as against global average of less than 1%. Active repair is preferred over Reactive methods to significantly reduce the technical losses in DT and improve reliability.

We have explored the feasibility of reducing technical losses in Distribution Transformers (DT) through Active Repairs over the currently prevalent Reactive repair methods. This proposed DT active repair enables to bring down no load and load losses proactively. This is a first-of-its-kind concept in the country and it is believed that there is a strong business case for Indian DISCOMs to consider this approach, on account of following reasons:
  • Reduces technical losses, thereby saving power procurement costs
  • Allows for further improvement in energy efficiency of transformers as mandated by BEE in PAT-2 cycle
  • Improves transformer reliability, thereby reducing downtime
  • Increases kVA capacity of the transformer
  • Creates an opportunity for the DT OEM or repairer to become a stakeholder in network O&M
When purchasing transformers it is important to compare the cost of the losses over the entire lifetime of the various types considered. DNV GL’s Transformer Loss Calculation Tool enables you to choose the economically most efficient transformer based on lifetime parameters such as capitalized cost, CO2 emissions, payback time and internal rate of return. In a clear summary table and intuitive graphs the tool provides you with additional information about the no-load and load loss evaluation (A and B factors), in case these are not known in advance. It calculates transformer losses when there are harmonics in the loading.

A pilot study was also undertaken We have undertaken pilot study on a 100 kVA & 200kVA DT at a public and private DISCOM respectively implementing the Active Repair solution.

Results for both pilots are in the white paper. Please download  to read more.

What We Do

International Copper Association India has taken up this project to improve the situation by advocating better technological options (EE distribution transformers) to reduce no-load and load losses. ICA India is promoting the use of low-loss, high-grade materials for the core and winding to result in low-loss, high-efficiency, Energy Efficient Distribution Transformers (EE DTs). The no load losses can be reduced by 75% and load losses by 40% by using Copper windings in place of Aluminium windings.

Transformer Market Scenario

Indian Transformers market size is approx. 266,000 MVA in 2012-13. The market is expected to year on year growth around 15% mainly due to the recent growth seen in the power sector & capacity addition of 88GW under the 12th five year plan.

DT Case Study

For more information on the case study

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