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Content archived on 2022-12-27

DEMONSTRATION OF ENERGY SAVING IN DISTRIBUTION TRANSFORMERS WITH AMORPHOUS METAL CORES

Objective

The aim of the project is to demonstrate substantial energy savings in a range of distribution transformers to be installed and operated at sites on the UK electrical distribution network. The novel feature is to use amorphous magnetic alloy as the core material to reduce losses to only 30% of the best equivalent conventional units with a material, production and installation cost premium of 25% or less. To gain sufficient operating data and confidence it is proposed to install around 65 transformers rated at 200, 100, 50 and 25 kVA at several sites. This represents an installed capacity of 4,500 kVA, five of the 200 kVA units would be installed and twenty each of the 100 and 50 kVA units and twenty five 25 kVA units at several sites where different types of load cycles would be applicable.
Two phase 3-limb wound type transformer cores were built. One was made from conventional electrical steel sheet (si-Fe) "Temcore" and the other from wound amorphous ribbon "Metglas". It was found that the third harmonic content of flux density is about 15% of the total flux density in the Si-Fe core and nearly 20% of the total flux in the amorphous core. These are considerably high and result in more loss in the core. The measured power loss was 0.73 W/kg and 0.174 W/kg for the Si-Fe and amorphous cores respectively at 1.3T 50 Hz. This is what one would expect since the amorphous ribbon is very thin and has higher electrical resistivity than grain-oriented sheet steel. The building factor is 1.5 and 1.1 at 1.3 T, 50Hz for Si-Fe core and amorphous core respectively. The market difference in building factor between the cores is due to the stress sensitivity of amorphous ribbon material, despite the fact that the amorphous core has been field annealed.
Amorphous magnetic material is potentially far superior to conventionally used silicon iron for transformer cores because of its poorer mechanical stress which has made it difficult to use. UWCC has carried out prior research and development with industrial partners which show how design and manufacturing difficulties can be overcome. New forms of core assembly, clamping, coil winding and core protection will be implemented to avoid degradation of magnetic properties and subsequent increase in core loss and harm and in-service performance. These techniques have not been demonstrated on a commercial scale in Europe. Amorphous cores are already used widely in USA because it is more easily applied to the low voltage, single phase pole mounted transformers
commonly used there. The project will not duplicate the USA work but is aimed to demonstrate that amorphous magnetic material can be widely used in 3-phase stacked cores widely used in Europe. It is proposed to demonstrate that transformers designed with amorphous alloy in their cores have losses 30% those of conventional equipment containing grain oriented electrical steel under normal service operation. Innovating methods of core design and manufacture will be used. Produce range and scope for statistical evaluation will be met by installing five 200 kVA, twenty 100 kVA, twenty 50 kVA and twenty 25 kVA units at sites throughout the UK.

Call for proposal

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Coordinator

University of Wales, Cardiff
EU contribution
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Address
THE PARADE 30 ROATH
CF2 3AD CARDIFF
United Kingdom

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Total cost
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