A device (1) for transmitting a signal through a body (2) made of dielectric material constituting insulation for an electric apparatus comprises: a first and a second electrode (3 A, 3B) connected to opposite ends of the dielectric body (2) along a longitudinal direction of transmission; a direct-current voltage generator (4), connected to the electrodes (3) for generating a direct-current electric field in the dielectric body (2) in the longitudinal direction of transmission; control means (5) connected to the generator (4) for producing at the interface between the electrodes (3) and the dielectric body (2) a predetermined charge, thus generating solitary charge waves (6) propagating from one electrode to the other at preset time intervals, the control means being configured to regulate the repetition frequency and/or the amplitude of the charge waves (6) according to the signal to be transmitted.