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.
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.
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.