The invention relates to a high-voltage dry apparatus having a semiconductor layer (2) covered by a metal screen (3), this screen (3) being eliminated so as to expose this semiconductor layer (2) over a length, this cable being connected to an element of equipment having an outer envelope (6) mechanically connected to said screen. According to the invention, an electronic monitoring arrangement (20) is contained within said envelope (6), this electronic arrangement (20) being electrically connected to an electrical power supply arrangement (21) surrounding said semiconductor layer (2) and to the metal screen (3) of said cable on either side of said length of the exposed semiconductor layer.