High-Efficiency Distribution Transformers

India currently has 7% Transmission and 26% Distribution Losses. we aim to reduce these losses which can be greatly possible by implementing energy efficient equipments. However, due to a large number of distribution transformers in electric power system and their long lifetime (30-40 years), even small improvement in the efficiency of these units could result in significant energy savings as it is important both from economic and ecological viewpoints.

A significant increase in energy efficiency of distribution transformers could be obtained by reducing no-load loss (iron or core loss) of the transformer. The use of amorphous metal in distribution transformers allows both liquid-filled and dry-type transformers with significantly reduced no-load loss.

 

No Load Losses for amorphous ribbon

1.   Hysteresis Loss:  Random molecular structure of amorphous metal causes less friction than Silicon steel when a magnetic field is applied. This unique property which allows ease of magnetization & demagnetization significantly lowers hysteresis losses in amorphous metals.

2.     Eddy Current Loss:  Amorphous metals have very thin laminations and high resistivity. This result in lower eddy current losses as compared to silicon steel.

As compare to standard liquid-filled transformers and amorphous metal core transformers representative the significant no-load loss reduction by up to 70% .

 

                                                                              Fig :  Transformer efficiency

An amorphous metal transformer (AMT) is a type of energy efficient transformer found on electric grids. The magnetic core of this transformer is made with a ferromagnetic amorphous metal. The typical material is an alloy of iron with boron, silicon, and phosphorus in the form of thin (e.g. 25 µm) foils. These materials have high magnetic susceptibility, very low coercivity and high electrical resistance. The high resistance and thin foils lead to low losses by eddy currents when subjected to alternating magnetic fields. On the downside amorphous alloys have a lower saturation induction and often a higher magnetostriction compared to conventional crystalline iron-silicon electrical steel.

In a transformer the no load loss is dominated by the core loss. With an amorphous core, this can be 70–80% lower than with traditional crystalline materials. The loss under heavy load is dominated by the resistance of the copper windings and thus called copper loss. Here the lower saturation magnetization of amorphous cores tend to result in a lower efficiency at full load. Using more copper and core material it is possible to compensate for this. So high efficiency AMTs can be more efficient at low and high load, though at a larger size. The more expensive amorphous core material, the more difficult handling and the need for more copper windings make an AMT more expensive than a traditional transformer.

More efficient transformers lead to a reduction of generation requirement and, when using electric power generated from fossil fuels, less CO₂ emissions. This technology has been widely adopted by large developing countries such as India and China where labour cost is low. AMT are in fact more labour intensive than conventional distribution transformer, a reason that explain a very low adoption in the comparable (by size) European market. These two countries can potentially save 25–30 TWh electricity annually, eliminate 6-8 GW generation investment, and reduce 20–30 million tons of CO₂ emission by fully utilizing this technology.

 

Amorphous Metal Transformer Benefits

• Up to 75% energy saving over conventional silicone steel
• Reduced emission of hazardous gasses such as CO₂ , SO₂ , etc.
• Reduction in fossil fuel consumption
• Fast & easy repair due to modular construction
• Reduced temperature rise of core
• Better Overloading Capacity because  lesser heat generation due to lower  losses.