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At present, most of the transformers used in distribution substations are silicon steel sheet iron core transformers (SST), which are connected between the power systems, and the iron loss (no-load loss) caused by the excitation of the transformer core, that is, standby power often occurs. If the SST of the same model grade is replaced by AMT, the iron loss will be reduced to less than 1/3, which is expected to achieve a significant energy saving effect. The saturation magnetic flux density of the latest amorphous alloy material is Bs=1.63T, which is smaller than that of silicon steel (2.0~2.1T). Therefore, compared with the SST of the same power, the cross-sectional area of the AMT core is about 1.3 times, and the increase in the size of the coil will cause the copper loss (load loss) to increase. However, the average load rate of most distribution transformers is 30-50%, so the reduction in iron loss exceeds the increase in copper loss, so the energy consumption rate of AMT is superior to that of SST. After a certain period of operation, it is economically beneficial of. Moreover, in the case of using renewable energy, due to the unstable output power, the standby power during low-load operation will become a problem that still needs to be solved. The application of AMT is expected to achieve the effect of reducing the environmental load.

The amorphous alloy material for the iron core is a sheet with a thickness of 25um. In the modern commercialized small and medium-sized power receiving and distribution AMT, thousands of such sheets are used. After shearing, lamination, and shearing ends overlap each other, A ring-shaped winding core is formed. In order to maintain the magnetic properties of the blank material, there is no bonding treatment between the sheets, so the amorphous alloy wound core is brittle, and a part of its weight is supported by the coil to maintain the structural shape. But when the AMT becomes large-capacity, this support method has limitations, and other structural forms should be designed. As a result, more metal components than SST must be arranged beside the coil, and the stray loss caused by the leakage magnetic field will increase. In addition, since the core must maintain its shape, the core's own weight will deteriorate the insulation between the sheets, causing a problem of increased iron loss. As a result, the magnetic and physical properties of the amorphous alloy material will be quite different from the original silicon steel sheet. So far, there have been no reports on the manufacturing examples of large-capacity AMTs.

In the face of the large-capacity AMT that has not been fully built in structure and is temporarily impossible to manufacture, this paper proposes a structural plan that can suppress the increase in iron loss and support the iron core. In order to verify its feasibility and effectiveness, the supporting structure and the coil with the core inside were trial-produced, and the results of the measured loss characteristics were explained. Moreover, for the large-capacity AMT with the proposed scheme, the analysis results of the stray loss related to actual load operation are used, and the improvement of power efficiency is also discussed.