Abstract: The device relates to a gas lightning arrester comprising a tight enclosure and at least two electrodes (2a, 2b). In the enclosure is placed a powdery mineral addition agent. This addition agent is a mixture of elementary or mixed metal oxides globally corresponding to the general formula Al X.sub.a Y.sub.b O.sub.c, in which formula X and Y respectively represent at least one alkaline or alkaline-earth metal, a is between 0.02 and 1.5, b is between 0 and 0.25 and c has the necessary value to comply with the valency rules. Can be used for the protection of the telephone lines.

Abstract: The lightning arrester device comprises an external metal casing (1) defining an enclosure (2) containing a neutral gas, and at least one metal rod (3a, 3b) forming an electrode and penetrating into the interior of the casing, insulating sealing means (4) being provided between the rod and the casing in order to close said casing, and comprising, moreover, at least one fusible element (5) adapted to create a short circuit between the electrode (3a, 3b) and the casing (1) when the quantity of energy to be diverted by the lightning arrester device exceeds a specified threshold.

Abstract: The surge protection element comprises an inert gas-filled protective device with electrodes inserted between two line input terminals, these terminals being connected respectively to branch terminals of an installation to be protected. The surge protection element also comprises initial protection apparatus, intended to be inserted between the terminals of the installation to be protected, and having a response time and a voltage threshold below that of said protective device, and also decoupling apparatus connected in series between the terminals of the protective device and those of the initial protection apparatus. The decoupling apparatus are capable of causing the voltage to rise at the terminals of the protective device when the current strength passing through the initial protection means increases, whereby the protective device can be tripped and can take over from the initial protection apparatus.

Abstract: A bi-polar discharger for a coaxial conducting cable is formed by threading rod elements into the ends of a central passage through an internal electrode so as to be electrically conductive therewith. A casing around the internal electrode comprises a cylindrical outer electrode closed at each end by a bead of glass or ceramic which is fitted within an outer metal ring and the casing is sealed with a controlled atmosphere of an inert gas at low pressure by sealing of the outer rings to the cylindrical external electrode and sealing of the rod elements within the beads.