Efficiency Improvement of an Electric-Grid Transformer Using the Diamagnetism Characteristics of a Bulk Superconductor

An innovative method to improve the efficiency of a single-phase electric-grid 125 kVA, 50 Hz shell type and distribution transformer is presented. The diamagnetism characteristic of a bulk high-temperature superconductor (HTS), designed in a specific dimension, is used to construct a magnetic shield around the air gaps that form between the core joints and among the coils of the transformer. Consequently, the shielded flux engages the core area and increases the flux density in the core, resulting in an increase in the output power, and hence an improved transformer efficiency. The transformer was designed and simulated using advanced electromagnetic software. Simulation results indicate that the width and thickness of the HTS material, as its precise location placed on the air gaps around the core and the coils, can be a substantial factor in generating a magnetic shield that results in an efficiency improvement, superior compared to conventional transformers. The most enhanced performance was received for HTS thickness of 2.6 mm, around 2.4% output power improvement compared with a conventional transformer model. In a transformer of this type that efficiency improvement can lead to great energy savings, around 10,000 kWh for half a year of working under load.