MT/LT dry transformer with linear distributed electric field for distribution of electric energy in rural networks

摘要

The system provides dry insulation of the transformer with semiconductor coatings controlling voltage distribution. The transformer comprises an isolating cylinder (3) for each of the phases, situated between the low tension winding (2) an the medium tension winding (6). The cylinder (3) is coated on its inner surface with a conductive or semi-conductive layer (4) which held at earth potential. The cylinder is coated on its outer surface with a semi-conductive layer (5) which provides a linear distribution of voltage. The medium tension winding is locally wound around this cylinder outer surface. The medium tension wind (6) has a structure comprising thin discs consisting of the superposition of layers of coils (9) wound in series, so that there an axial distribution of potential.