Low-cost dielectrics for power distribution transformers

With the continuing improvements in HTS conductors, the application to power distribution transformers becomes possible as well as economical. To realize a viable design, many system aspects must be addressed including the thermal and dielectric characteristics of the winding insulation. This work reports on the study of cellulose-based dielectric insulation and transformer-board for dry-type (conduction cooled), 50 kVA to 5000 kVA, medium-voltage, high-temperature superconductor transformers. Results of electric-field strength studies and tests are presented.