Abstract: A coaxial cable fuse having a central conductor, an outer conductor disposed coaxially with respect to the central conductor, an insulating medium disposed between the central conductor and the fusible outer conductor, and an insulating layer covering the fusible outer conductor. The outer conductor may be composed of fusible conductor for causing an open circuit to be formed in the outer conductor in response to an electrical current passing through the outer conductor. The open circuit is formed prior to any substantial heating of the exterior insulating layer of the coaxial cable to which the fuse is attached to reduce the likelihood of fire hazard due to heating of the insulating layer. The coaxial cable fuse may be used in an electrical interface apparatus adapted to interconnect a coaxial distribution cable and a premise coaxial cable. The electrical interface apparatus has a housing and a coaxial cable protector with a surge protector and a fail-short mechanism disposed in the housing.

Abstract: An electrical load, such as a motor, has a first and a second terminal element for supplying electricity to the load. The second terminal element is directly connected to the load whereas the first terminal element together with a further terminal element forms a clamping socket for a switching device. The further terminal element is electrically connected to the load. When the switching device is inserted into the seat, the first terminal element is connected to the load in series with the further terminal element via the switching device.

Abstract: A protection device which includes an insulating tube closed at each end by a fuse cap. Electrically connected to one cap is a contact plug, and to the other cap a spring and a contact plunger. Sandwiched between the plug and the plunger is a combustible separator configured to disintegrate when the potential difference between the plug and the plunger exceeds a predetermined amount. This disintegration permits the spring to bias the plug and the plunger into electrical connection thus eliminating the potential difference. The protection member contains an accelerant to increase its rate of disintegration. The device is used to protect neon lighting systems from open circuits.

Abstract: A protector module includes two input prongs receiving electrical signals from an outside plant, two output prongs outputting electrical signals to exchange equipment, a ground prong for grounding an abnormal signal induced by lightning strikes, an indicating device, a printed circuit board defining a plurality of pad portions and through holes, and two blocks each receiving a plurality of arresters, thermistors, and tin bits and respectively mounted on a first surface and a second surface of the printed circuit board.

Abstract: A telephone line surge protector module with fast-acting, high resistance heat coil assembly includes a plurality of turns of resistive heating wire having a conductive core, a heat-resisting insulative coating, and a relatively high tensile-strength serving for resisting manufacturing stresses. The serving permits a number of turns of the wire to be tightly wound about a bobbin, without being damaged due to stresses encountered in the manufacturing process. The heat resisting insulative coating prevents shorting between the turns at high temperatures, yet is thin enough so that inter-turn thermal conductance is not degraded. The serving is preferably formed of a material that softens or liquifies at high temperatures to enhance inter-turn thermal conductance. The module with fast-acting coil is suitable for protecting sensitive electronic digital switches.

Abstract: In a three-electrode surge arrester where the center electrode (3) is provided with a connecting wire (6) that projects outward radially and is provided with an outside short-circuit device, the latter consists of a two-arm spring clip (20) whose arms project axially beyond the free ends of the end electrodes and are in contact with the outside peripheral edge of the respective end electrode (1, 2) with a layer of insulating film (21) in between. Spring clip (20) has an roof-shaped arch (24) and is provided with a passage in the area of this arch that serves to secure the spring clip on connecting wire (6) of center electrode (3).

Abstract: A surge protector includes a housing having therein a wire wound resistor and a fuse separated by a partition wall. In one embodiment for use with high density information transmission, the resistor is of very low value and preferably is 5.6 ohms. The leads from the resistor and fuse are glued in position. The resistor wire is wound about a mandrel and is widely spaced to prevent arcing between adjacent coils of the resistor. A high temperature coating covers the resistor coils and mandrel effectively immobilizing the coils from movement in response to a magnetic field generated when high voltage is applied to the resistor. A cover closes the housing and conceals the components. The housing is empty of potting material.

Abstract: Disclosed is a voltage and current protector device designed for connecting blocks with a high density of contacts. Thermal overload protection is provided through a special ground connector with one end mounted over the surge protector element rather than through the normal ground pin of the element. The ground connector at its other end is shaped into a detent for capturing the ground bar of the connecting block.

Abstract: A surge arrester for protecting power distribution equipment from overvoltages has a varistor as the active surge-arresting element. In the event of a persistent overvoltage, an amorphous conductor electrically in series with the varistor heats up to or above a critical temperature at which its tensile strength substantially decreases. The amorphous metal conductor breaks, triggering a series of events including the closing of a switch creating a permanent short to ground, operating the network overcurrent protection to de-energize the arrester and associated protected equipment, and protecting the electrical network equipment from insulation damage and/or failure because of a sustained or permanent power frequency overvoltage condition.

Abstract: A fused disconnect switch including a plurality of maintenance and installation enhancing features is disclosed. For example, a bipolar LED is provided as an alarm indicator so that the fused disconnect switch will function in power distribution systems which operate on both positive and negative voltages. Additionally, a manual test tab is provided for checking the alarm circuitry and a viewing window is provided so that the presence or absence of a fuse in the fused disconnect device can be ascertained without removing the fuse holder.

Abstract: A vent-safe protector for a telecommunications gas tube (102) includes two electrodes (108,140) (150',140) separated by a non-linear resistive material (134). Each electrode is connected to a gas tube protector terminal (108, 142) to provide an alternate discharge path if the gas tube (102) fails. The non-linear resistive material (134) is substantially non-conductive when the electrical potential between the electrodes is less than the material's breakdown voltage V.sub.B. Above that voltage it becomes conductive and supports a plasma discharge therethrough, effecting a sudden increase in conductivity between the electrodes for discharging high energy potentials with a voltage foldback functionally analogous to the foldback behavior of the gas tube protector.

Abstract: This invention discloses a network termination module comprising a base structure having a means for grounding. Mounted on the base structure is an intermediate structure which contains a telephone jack and also a pair of line terminals for connection to telephone company wiring. A terminal strip is mounted above the intermediate structure, the terminal strip containing subscriber terminals for connection to a subscriber's wiring. Mounted above the terminal strip is an openable cover containing a telephone plug which mates with the telephone jack. The line terminals are electrically connected to the telephone jack. There is a protector element disposed in the base structure which is electrically connected to the means for grounding.

Abstract: The termination resistor of an electronic apparatus is connected in series with a thermistor PTC switch thermally coupled to the resistor. Excessive power dissipation in the resistor causes the PTC switch to trip, and the increased total resistance limits power dissipation in the resistor to safe levels. The PTC switch and the resistor may be merely in close physical proximity to one another to achieve the thermal coupling. Alternatively, the two may be fabricated as a unit assembly whose form factor is that of, or is similar to that of, the resistor that would otherwise be used by itself.

Abstract: A surge arrester assembly includes an electrically conductive container having disposed therein a surge arrester and a meltable element. The surge arrester has a first electrode in electrical contact with the container and a second electrode not in electrical contact with the container. The meltable element is an electrically conductive element in thermal contact with the surge arrester. The meltable element is located and configured so as to melt in response to a selectable level of thermal energy generated by the surge arrester, in such a manner as to create an electrical short circuit between the first electrode and the second electrode.

Abstract: A surge protector is adapted for a broadband coaxial system in which electrical signals having a frequency range from DC to one gigahertz are transmitted. The surge protector has a pair of coaxial cable connectors, a surge protection device, and a fail-short mechanism. The fail-short mechanism has a first operating condition in which the center and outer conductors of the coaxial cable connectors are isolated from each other and a second operating condition in which the center and outer conductors of the coaxial cable connectors are conductively coupled to each other. The impedance of the fail-short mechanism allows the surge protector to have an insertion loss with a magnitude not greater than about -0.2 decibels and a return loss having a magnitude of at least about -20 decibels, and the fail-short mechanism is adapted to conduct a fail-short current having a magnitude of at least about 30 amperes for at least about 15 minutes when the fail-short mechanism is in its second operating condition.

Abstract: A protector arrangement is disclosed having first and second protector terminals, a gas discharge tube, and a metal oxide varistor. The gas discharge tube is connected to the first and second protector terminals. The metal oxide varistor is connected to the first and second protector terminals so that the metal oxide varistor acts as a backup to the gas discharge tube and so that the first and second protector terminals are automatically shorted in response to a thermal overload condition. The protector arrangement may be mounted in a weathertight housing.

Abstract: An arc suppressor for a sidactor type protective device wherein the sidactor type protective device comprises a sidactor body portion, two end line terminals, a central ground terminal, and a fail-safe mechanism mounted upon the terminals of the sidactor in order to shunt or short-circuit the sidactor under overload conditions. The arc suppressor comprises a housing or cap tightly enveloping or encasing the sidactor body portion so as to enhance the strength thereof and thereby maintain the structural integrity of the body portion by effectively preventing any cracking thereof under overload conditions. The prevention of the cracking of the sidactor body, in turn, insures that any plasma gas or cloud generated within the sidactor body under high-voltage overload conditions is contained within the sidactor body and does not escape therefrom so as to otherwise present an environment conductive to arcing between the terminals of the sidactor.

Abstract: A gas-tube arrester includes an arrester body in which an inert gas is contained, and first and second electrodes face each other separated by an insulator. An insulating, heat-resistant film is in contact with the first electrode and has a plurality of small holes. A low-melting point metal plate layered on the insulating film has a melting point lower than a decomposition or softening temperature of the insulating film. A conductive leaf spring electrically connected to the second electrode presses the low-melting point metal plate toward the insulating film, so that, when a high voltage is applied between the first and second electrodes, an electrical discharge occurs between the first and second electrodes through the small holes of the insulating films.

Abstract: A grounding arrangement for a protector includes an arrester device having two conducting points for connecting to inlet prongs and a grounding point having a protruding rod for connecting to a grounding prong, an arrester holder for receiving the arrester device and having two longitudinal extension portions for connecting with the two conducting points, and a tin bit provided for electrically connecting the holder and the grounding point of the arrester device and isolating the holder and two conducting point of the arrester device.

Abstract: A protection structure for a surge absorbing element for protecting equipment such as communications lines from surges caused by lightning or the like which makes use of a surge absorbing element in parallel with the equipment to be protected and a low melting point metal wire in direct contact with the element and in series therewith. The structure protects the surge absorbing element or assembly from continuous overvoltage or overcurrent which may be generated by a short-circuit of an alternating electric current source and the like.

Abstract: A transient voltage surge suppressor (10) is used in a single or poly-phase power distribution network (P). The surge suppressor connects in parallel between each phase (A, B, C) and neutral (N), each phase and electrical ground (G), and between neutral and ground. An improvement comprises an electrical circuit (30) for monitoring the loss of surge protection due to the occurrence of a current surge or voltage transient in a neutral-to-ground path (32). An MOV-type semiconductor (VR1) is connected in the ground-to-neutral path. The semiconductor is normally non-conducting, but switches into conduction when its voltage threshold is exceeded by a surge current or voltage transient. An excessive surge or transient causes the semiconductor to fail. Respective fuses (F1A, F2B) are connected in series with the semiconductor. These fuses clear (blow) upon a semiconductor failure to create an open circuit neutral-to-ground path.

Abstract: A surge arrester arrangement comprising includes a surge arrester (4) and a cut-out device (6) arranged in series with the arrester for automatic disconnection of the arrester in the event of arrester failure. The arrester arrangement is intended to be connected in parallel with an insulator (2) arranged for suspension of a power line (1) from a power line tower (3). The surge arrester (4) is connected to the power line (1) via a connecting link (5) in the form of a flexible electric conductor (10) enclosed in a tube of, for example, aluminium, which is divided into several parts, A helical spring (8) which, for example, may be arranged inside the tube, keeps the connecting link at insulation distance from the power line (1) when the arrester has become disconnected by means of the cut-out device (6).

Abstract: An improved fail-safe mechanism is provided for use with a sidactor for protecting telecommunication equipment against high voltage surges. A sidactor includes first and second end terminal pins and a central terminal pin. The fail-safe mechanism consists of a torsional type spring and a pair of insulators. The torsional spring includes a single looped portion and a pair of spring arms extending radially outwardly from the opposite sides of the looped portion. The spring arms of the torsional spring are initially formed so as to have an obtuse angle therebetween. The center of the single looped portion is disposed off-centered in relationship to the centers of the first and second end terminal pins of the sidactor during assembly in order to assure that sufficient and constant pressure is applied between the spring arms and the end terminal pins.

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: A surge arrester for telephone lines comprises a threaded metal enclosure for insertion into a threaded well of a station protector. The protective element within the threaded metal enclosure is a voltage sensitive solid state switch comprising a semiconductor chip sandwiched between two flat electrodes. One electrode is in contact with a metal plate which is in contact with a solder disc. The other electrode is in contact with a metal post disposed in, and extending through, a plastic spacer within the threaded metal enclosure.

Abstract: This invention relates to a protection module provided to receive an overvoltage arrester in a receptacle and designed to plug on the protection ring of a telephone line interconnection module. The receptacle presents a receiving cavity adapted to receive overvoltage arresters of different dimensions, and it contains three elastic contacts, viz. two line contacts each with two contact strips and an earth contact with contact clamp. A thermofusible insulating shim is inserted between four additional earth lugs and the body of the overvoltage arrester in order to ensure short-circuiting of the latter in the event of functioning due to a lightning strike.

Abstract: An overvoltage protection apparatus used with a pair of telephone lines includes first voltage clamping circuitry for clamping voltage signals on the lines at a first predetermined voltage potential. The first voltage clamping circuitry is formed by at least a pair of solid-state protective chip devices and a failure mode mechanism adapted for connecting the lines to ground responsive to increased temperature of the solid-state protective chip device and providing a ground connection for the pair of solid-state protective chip devices. A pair of current limiting resistors operatively connected to the failure mode mechanism provide sneak current protection.

Abstract: A telephone line overvoltage protection method and device are provided. An overvoltage protection apparatus used with a pair of telephone lines includes first voltage clamping circuitry for clamping voltage signals on the lines at a first predetermined voltage potential; second voltage clamping circuitry for clamping voltage signals on the lines at a second predetermined voltage potential. The second voltage clamping circuitry includes filter circuitry for filtering the voltage signals when the voltage signals exceed the second predetermined voltage signals. The first voltage clamping circuitry is formed by a solid state protective device and a failure mode mechanism adapted for connecting the lines to ground responsive to increased temperature of the solid state protective device.

Abstract: An arrester assembly for arresting over-voltage conditions in electric circuits and for isolating an arrester element from possibly harmful effects of external forces applied to the arrester assembly comprises a hollow cup and an arrester element located within the cup for arresting over-voltage conditions. A plastic sleeve is disposed within the cup surrounding the arrester element for isolating the arrester element from the possibly harmful effects of external forces applied to the assembly. A spring may also be provided within the cup for further isolating the arrester element from such effects.

Abstract: A gas-tube arrester includes an arrester body containing an inert gas and having first and second electrodes positioned in spaced, facing relationship to each other and separated by an insulator. An insulating, heat-resistant film is in contact with the first electrode and has an opening and a plurality of small holes. A metal plate layered on the insulating film has an opening communicating with the opening of the insulating film. A low-melting point metal plate layered on the metal plate to cover the openings has a melting point lower than a softening temperature of the insulating film.

Abstract: A MELF (Metal Electrode Face Bonding Device) surge absorbing element which can be connected across a pair of input lines of an electronic device. The surge absorbing element is secured in electrical contact with the input lines by a conductive heat releasable adhering means, e.g., a solder. A spring is positioned in biased relationship against the surge absorbing element. When the surge absorbing element is subjected to overvoltages or overcurrents continuously across the input lines, the surge absorbing element heats up, which, in turn, heats the adhering means. When the temperature reaches a predetermined value, the adhering means releases its securement of the surge absorbing element, e.g., the solder melts, and no longer holds the element. When this occurs, the bias of the spring means positioned against the now unsecured surge absorbing element serves to move the element away from and out of electrical contact with the adhering means and, in turn, the input lines.

Abstract: A surge absorber in which a thermal response switch is inserted in an input line at the input side of a surge absorbing element. The switch includes a conductive spring piece and a conductive hook piece. The base end of the conductive spring piece is fixed on either the first lead or the second leads and the tip of the conductive spring piece is provided with a pawl. The base end of the conductive hook piece is fixed on either the first lead or the second leads and the tip of the conductive hook piece is engaged with the pawl. At least one of the conductive spring piece and the conductive hook piece is made of a thermal response piece. Upon stopping of the applied continuous overvoltages or overcurrents, the switch can automatically be restored depending on an extent of the overcurrent by a manual operation.

Abstract: A miniature station protector module for communication systems includes a hollow housing into which is disposed a pair of line terminals with a ground terminal therebetween. The line terminals extend into the hollow housing and include thereon a back-up surge arrester in axial alignment with each of the terminals, either a three terminal surge arrester or a pair of two terminal arresters may be utilized having one electrode connected to the ground terminal with the other electrodes being connected to the line terminals.

Abstract: A miniature solid state surge protector apparatus for use in telephone central offices, or the like, that are provided with terminal blocks for communication lines which may include an in-line overcurrent coil arrangement that grounds each communication line if an overcurrent flows therethrough and is additionally provided with a solid state miniaturized surge protection device disposed across a pair of communication lines and a common ground terminal, thus providing overvoltage and overcurrent protection (fail short) to a pair of telephone communication lines.

Abstract: A miniature solid state surge protection device having an unsealed solid state device having first and second electrodes with the first electrode in contact with a fusible pellet is provided. When a surge occurs the pellet melts to thereby short the first and second electrodes together.

Abstract: The surge absorber having a surge absorbing element, and first and second wire means for electrically connecting the surge absorbing element across the input lines of an electronic device. The first and second wire means are connected to the surge absorber by conductive heat releasable means, for example, a low melting point solder. The second wire means includes a spring loaded member such that, on release of the first or second wire means by the first or second heat releasable means, respectively, by melting of the solder due to heat generated by the surge absorbing element, the surge absorbing element moves away from the first or second wire means. The surge absorber prevents an abnormal heating of the surge absorbing element when continuous overvoltages or overcurrents pass therethrough.

Abstract: A line protector for a communications circuit comprises a housing, an over-voltage arrester received in said housing and having axially opposite electrodes and a ground strip for coupling one of the electrodes to electrical ground. An over-current arrester has at least one line contact for electrically contacting a communications line. A conductive sleeve electrically contacts a second communications line to be joined with the first communications line, the sleeve also being assembled with the over-current arrester and with the over-voltage arrester, such that the over-voltage arrester is held within the housing. The sleeve has projecting fingers for completing an electrical circuit between the second communications line and the other of the electrodes of the over-voltage arrester.

Abstract: A heat generating means, such a resistive element, is serially connected in a current-carrying conductive line, and a fusible link carrying current from said line is serially mounted between the line and said resistive element and is positioned in proximity to the heat generating means, to be heated by the heat from the generating means and to melt in response thereto, thereby breaking the serial connection in the current-carrying line. A spring means may be provided to urge disconnection of the serial circuit when the fusible link melts.

Abstract: A telephone protector comprises an encapsulated bidirectional voltage sensitive switch having three terminals protruding therefrom, one of the terminals being a grounding terminal. There is an elongated shorting bar substantially orthogonal to the three terminals and a metal fusible pellet in direct physical contact with both the grounding terminal and the shorting bar. There is a spring which impels the shorting bar into contact with the other two terminals when the fusible pellet melts.

Abstract: A fail-safe device is provided for an overvoltage protector element where the protector includes a body having first and second contact surfaces and a tip lead, a ring lead and a ground lead extending from the body. The fail-safe device includes a heat deformable dielectric base and an electrically conducted spring member having first and second contact ends. The base is disposed against the element body with the base having first and second spacer ends separating the spring's first and second ends from the protector body's first and second contact surfaces.

Abstract: The surge protector includes a device for connecting a transmission line to ground in the event of excess voltage or current, to protect communications equipment. A thermal sensitive element, located proximate the device, provides an independent, permanent path to ground, before the device can heat to a level where it may fail in the open circuit state. The element is a grounded conductive rod of nickel-titanium alloy which has a configuration memory. The rod normally has an arcuate configuration with a portion spaced from the transmission line contact associated with the device. It will assume a straight configuration, connecting the transmission line contact to ground, if the device overheats. Thermal failsafe protection for protective devices associated with ring and tip conductors, respectively, can be provided with a single thermal sensitive element.

Abstract: The invention relates to a protective plug (1) for connector banks (20) of telecommunication and data systems, comprising a housing (2) for receiving protective elements (7, 8, 9) connected to establish an electrical connection to an earth rail (44) and with a disconnector contact (43) to a bifurcated contact (41) or to circuit tracks (10) provided on a plug tongue, resp. The disconnector contact (43) is provided with terminal contacts (53) for incoming and outgoing cable conductors. In order to provide a protective plug (1) which protects against overvoltages and serves as well as a fuse against overcurrents and for which the outside dimensions allow a close-fit construction of several protective plugs (1), the plug tongue (5) is a printed-circuit board (4, 4a) extending into the housing (2). Two housing compartments (21, 22) are formed inside the housing (2).

Abstract: An overvoltage protector for protecting equipment, especially telephone equipment, against high voltage surges such as are caused by lightning in the vicinity of the equipment or the cables to which it is connected, comprises one or more overvoltage protectors (42,58) mounted upon one face of an insulating support (18). A generally planar contact member (62) mounted upon the support member has a ground contact member (90) to make contact with a ground electrode (114) in the equipment to be protected and with each overvoltage protector. A spacer (60) of fusible plastics material extending between the contact member (62) and an interconnection (26) to one terminal (42A) of the protector melts when a sustained fault occurs. As the spacer melts, it permits an electrical connection between the contact member and the line to which the overvoltage protector is connected, effectively short-circuiting the line to ground.

Abstract: Electrical transient surge protection of electrical equipment downstream from a power source plus safeguarding of apparatus for providing such surge protection against failure at high currents or high temperature. Distributed-resistance fuse links facilitate operation of non-linear over-voltage means, such as varistors, in clipping transient voltage surges and shunting resulting currents to ground so as to protect watt-hour meters and downstream loads from electrical surges, and to safeguard such varistors from failure. Such apparatus may be located in such diverse places as a power line weatherhead, a watt-hour meter base, an adapter between a meter base and its normal mounting socket, or a utility panel having such a socket, or in a circuit-breaker panel downstream of the meter and upstream of metered loads.

Abstract: A device for connecting and then isolating and disconnecting an arrester has a first electrical terminal, a second electrical terminal and first and second circuits for electrically connecting the first and second terminals. The first circuit includes a conductive casing mechanically coupled to the first and second terminals and a spark gap located between the outside of the casing and second terminal. The second circuit includes an interrupting mechanism for automatically interrupting connection between the first and second terminals.

Abstract: A five pin protector module for telephone circuits comprises two input pins, two output pins and a grounding pin, all on an insulative base. The electrical current path between each input pin and its respective output pin comprises an electrically conductive arm, a current responsive assembly and an electrically conductive helical spring. The module contains a bidirectional voltage sensitive switch which prevents input voltage surges from reaching the output but, instead, conducts them to a grounding member to which the grounding pin is attached.

Abstract: A fail-safe arrestor for electrical circuits utilizes a gas-filled tube to conduct at an over-voltage and also provides a clip to solidly couple the circuit to a ground lead at the melting from continuous current flow of an insulator interposed between an electrode and the ground lead, which insulator is a mesh with a plurality of passages allowing arcing between the electrode and clip at or above a predetermined voltage, and thus the ground lead, for a vented gas-filled tube.

Abstract: A gas tube fail safe device for use in individual subscriber circuit telephone mmodules and related equipment, in which a fusible element is adapted to by-pass the conductive function of the gas tube in the event of gas tube failure. In one embodiment the construction provides for the fusing of the fusible element upon the occurrence of a sustained current overload. In another embodiment, this operation is supplemented by provision of secondary air gap means operative upon the occurrence of momentary excess voltage surges in the presence of a defective gas tube.

Abstract: An improved telephone subscriber circuit protector module providing plural surge voltage and excess current protection elements including so-called sneak current protection. The module includes a three-element gas tube which protects against voltage surges in the range of 200 to 300 volts, and includes fail safe protection relative to the gas tube should the gas tube become non-conductive over its intended range of protection. The fail safe protection is thermally operated under the influence of high current. Secondary air gap protection supplements the operation of the gas tube in the event of gas tube failure, and is operative to ground momentary voltage surges in the area of 1500 volts. Separate sneak current protection employing heat coils are operative in a range below one ampere flow, and an alternate form provides for the opening of the subscriber side of the line rather than the grounding of it. All of the protective elements communicate with a common ground plane forming part of a ground assembly.

Abstract: In a gas-filled arrester, a pair of main electrodes and a ground electrode are air-tightly fitted to an insulating tubular member. A springy, electrically-conductive short-circuiting element having an arcuate shape is fitted around the outer wall of the ground electrode. The short-circuiting element includes extension portions extending along the outer wall of the insulating tubular member to the respective main electrodes, and these extension portions are made to face the main electrodes by utilization of spring characteristics thereof with a certain gap maintained and with a thermally-fusible spacer interposed. With this construction, if the arrester is overheated, the spacer is thermally fused by heat and therefore the extension portions electrically contact the main electrodes due to the spring characteristics thereof. Since the main electrodes are thus short-circuited to the ground electrode, the arrester is prevented from failing.