Demonstration of Loss Reduction Effect of 66kV-Classed 30MVA Three Phase Hybrid-Core Transformer by Trial Manufacture

Abstract

To realize larger-capacity “Hybrid-core transformer: HBT”, this research has assembled a 30-MVA three-phase trial HBT and evaluated the loss performances. The hybrid-core consisting of the wound amorphous- and the stacked silicon steel-cores, is expected having advantages of lower iron loss of the iron-based amorphous material and the higher mechanical strength and saturation magnetic flux density of the silicon steels simultaneously. Three-dimensional finite-element method analysis revealed that the silicon steel core prevented over-saturation of the amorphous core. The hybrid configuration enabled the design to have an approximately 10% higher magnetic flux density than configurations with only an amorphous core. We then assembled a prototype 30-MVA three-phase HBT designed on the basis of our investigation results. Operation tests demonstrated that the HBT has 62%-reduced iron loss and 0.10%-higher 50%-loaded power efficiency from the conventional silicon steel core transformer.