Plug changer for oil-filled electrical transformers

Abstract

A tap changer for oil-filled electrical transformers, comprising: a guide element (2) provided with a plurality of electrical contacts (3) and a slide (4) capable of sliding along the guide element (2) to change the electrical connection between two or more electrical contacts (3); means for moving the slide (4) comprising a drive group (6) having at least one rotating part (8) and defining a plurality of discrete positions of the carriage (4) relative to the guide element (2), each corresponding to an electrical connection between the different electrical contacts (3).The displacement means (5) comprising: a ring-nut (20) capable of being rotated by the drive group (6) and whose lateral surface has two or more flat surfaces (21); a core (23) counter-displaced with the lateral surface of the ring-nut (20), the part (24) of the core (23) facing the ring-nut (20) having a flat surface (25) sensitive to being arranged one by one with the flat surfaces (21) of the lateral surface of the ring-nut (20) when the slide (4) and the guide element (2) are placed in correspondence with one of the discrete positions.