Abstract: A gas-filled three-electrode overvoltage arrester may be developed in such a manner that it has dependable "fail-safe" and "vent-safe" behavior. For this purpose, a two-arm spring clip (10) is fastened to the center electrode (1). The ends of the two-arm spring clip (10) rest, with the interpositioning of a spacer (20, 21; 22, 23), against the ends of the end electrodes (2, 3). The end of each arm of the spring clip bears a cap (14, 15) which is provided with a flange-like edge (16, 17). One end of the connecting wire (6, 7) of each end electrode has the shape of a ring (61, 71) which is fastened at the end side to the end electrode. The ring of the connecting wire and the flange-like edge of the cap are opposite each other and are held apart by a disk-shaped fusible pellet (20, 22) and a cylindrical part (21, 23) having insulating properties. The cylindrical part consists either of a temperature-resistant insulating material or of a metal-oxide varistor.

Abstract: As a known "back-up device" for a gas-filled over-voltage arrester, a voltage-dependent resistor (6) is arranged centrally in a housing with the over-voltage arrester (1). The varistor (6) can, in this connection, be sealed with a moisture-repelling substance and it is arranged concentrically to a connecting pin (5) of the over-voltage arrester. By means of an auxiliary electrode (8) of annular disk shape placed on the varistor (6), an air gap (13) from the connecting pin (5) can be formed. The varistor, after its response, can be short-circuited via this air gap.

Abstract: An electrode activating compound for a gas discharge tube such as a surge voltage arrester, triggerable gas discharge tubes and flash tubes in which a titanium oxide is used in place of the radioactive thorium oxide. Preferably, the titanium oxide is provided by a reduction of a titanium dioxide with a reducing agent such as BaAl.sub.4 or metallic titanium or by oxidation of a titanium hydride in either an oxidizing atmosphere or with an oxidizing compound.

Abstract: A surge voltage arrester has a gas-filled housing in which main electrodes are disposed opposite one another, and supported by a tubular insulating member on whose interior side at least one ignition strip extends over a portion of the tube length. There is applied, on the exterior side of the insulating member at least one electrically conductive layer, clamp, or electrode, which at least partially overlaps, from the exterior, the ignition strip. The arrester has a low impulse breakdown voltage, so that the difference between the impulse breakdown voltage and the DC breakdown voltage is substantially reduced.