Abstract: A protector module (30) for protecting tip and ring conductors of a telepe loop includes a pair of protector assemblies (40--40') which are supported within a common housing (32). A voltage protection subassembly (42) of each protector assembly is connected electrically to a grounding subassembly (44) for causing current associated with excessive voltage surges to be conducted to ground. Each protector assembly also includes a current protection subassembly (41) which comprises a dielectric base, as well as a tubular line pin (61) and a central office pin (57) which are connected together electrically. A shunting element (62) is disposed concentrially about and is supported at one end of the line pin in an initial position by a pellet (70) of a fusible material which extends between a closed end of the shunting element and an edge surface (68) of an open end of the line pin.

Abstract: A male base subscriber pair protector module in which substantially all of the internal components thereof are assembled upon an axially elongated base element prior to insertion within a module housing, thereby facilitating manufacture and allowing the use of a wide variety of existing components which are readily adapted for such assembly.

Abstract: An electrical component comprising a temperature responsive device including an electrically conducting member (1) of spring temper in contact with a thin insulating coating (3) of a substance which decomposes on being subject to an elevated temperature thereby allowing the conducting member (1) to effect a short circuiting operation. Suitably the conducting member (1) is coated with a thin layer of polyurethane varnish which vaporizes at the elevated temperature, and the conducting member (1) is arranged to engage contacts (5,5) under spring tension. In one embodiment the conducting member (1) is a wire of phosphor bronze or beryllium copper formed as a loop (2) with spring arms, the loop (2) being positioned on a pin 4 centrally disposed between spaced contacts (5) engaged by the arms under spring tension.

Abstract: A protector for telephone systems and similar systems is in the form of an elongate housing formed by two hollow box-like members, one fitting within the other. In the bottom member, a line terminal is provided at each end, each terminal connected to a line contact member in the housing. A ground terminal is provided at a mid position in the bottom member, connected to a support and ground member. A protector device assembly is mounted in the support and ground member, providing a breakdown gap connected between each line contact member and the ground. The device assembly can be two-electrode gas tube devices, a three-electrode gas tube device, or other devices. Back-up protector devices are positioned between each line contact member and the support and ground member.

Abstract: A module for the protection of multiwire lines against overvoltages comprises a casing formed by a receptable and a terminal carrier plate. The terminal carrier plate comprises a pair of terminals for each wire of the multiwire line, and an earth terminal. Overvoltage diverters are connected to said wires and each have a first electrode soldered to a U link which connects, the two terminals of each pair of terminals, and a second electrode soldered to a transverse bar itself soldered to an extension of the earth terminal. The subassembly connected to the terminal carrier plate is disposed within the receptacle and is potted in a plastic potting substance. This module may be used for the protection of telephone lines.

Abstract: A three element gas tube type subscriber pair protector module in which the gas tube serves as both a momentary surge protector and a heat responsive means directly operable upon a pair of fusable elements. The number of component parts has been minimized, permitting low manufacturing cost and simplified assembly.

Abstract: In response to spurious signals in a circuit connecting telecommunications equipment with a serving central office, the signals will pass through terminals of a protector module and through a protector unit inserted in the circuit causing a lead pellet to melt or the air gap between carbon blocks to short and establish a path to ground so that the spurious signals may be grounded. When the protector unit is removed from the protector module, the circuit remains grounded until the protector unit is replaced. Alternatively, when the protector unit is removed, the electrical path of the circuit is opened by introducing an insulator in the path of signals between the terminals. In one embodiment, in the open circuit condition, unusually high voltages arc over from the protector terminals to a metallic pin and then to ground.

Abstract: A station protector for communication lines includes an electrical conductor formed for connection to the communications lines and affixed to a base member, a grounding means affixed to the base member, an arrester cartridge disposed in an aperture in the base member and a biased resilient member electrically coupling the electrical conductor to a surge voltage arrester or to circuit ground in the absence of the arrester.

Abstract: A protector module, or assembly, for telephone lines and similar systems, has line terminals and a ground terminal in the base. The line circuit is between a related pair of line terminals. The line circuit includes part of a line bracket which extends up the side of the housing. The line bracket extends to the outer end of the housing and an aperture in the end of the housing permits access by a test probe to the line bracket. Normally, two line brackets are provided each associated with a pair of line terminals. A ground bracket also extends up the housing, being connected at one end to the ground terminal and having a flange at its other end. Between the outer end of the line bracket and the flange on the ground bracket a back-up or other form of protector member can be positioned.

Abstract: A power line transient surge suppressor circuit features a nonlinear surge-bypassing network connected to bypass line surges around electrical loads connected to circuit output terminals. A fuse is inserted in series with the network, and blows in the event of short-circuit failure of a regulator device in the network. A thermal cut-out preferably of the irreversibly actuated type is inserted in series with the suppressor circuit input. A current-limiting heater resistor connected in parallel with the fuse supplies heat to trip the cut-out after the fuse blows, thereby permanently terminating power output to the loads. A similar suppression network is provided for the earth lead in three-wire systems.

Abstract: An improved telephone protector module for individual subscriber circuits of generally planar configuration, and having heat-sensitive means employing a solder pellet which, upon melting, flows through capillary action to effect a shorting to ground. Secondary air gap means is provided by spacing a pair of conductive parts using a thin insulative wafer having openings therein forming an interruption in the insulation.

Abstract: A subscriber pair protector module of gas tube type in which the heat coil assembly is supplemented by the provision of a planar fusible member placed in direct contact with the gas tube elements to provide a heat sink for a limited period of time to protect the module until the heat coil assembly becomes operative, thereby preventing damage to the synthetic resinous housing element of the module which would interfere with its subsequent removal. An improved gas tube element is also disclosed having recesses disposed in the end surfaces thereof to prevent total shorting action by the heat coil element until the planar fusible member has melted. An improved gas tube element is also disclosed having recesses disposed in the end surfaces thereof to prevent total shorting action by the heat coil element until the planar fusible member has melted.

Abstract: A line protector for a communications circuit provides overvoltage and overcurrent protection. The overvoltage protection is attained through an arrester that provides an arc gap from the line to ground. For overcurrent protection, a fusible element is melted by a heat coil causing the line to be directly grounded. A test terminal is in conductive connection with the line circuit and extends to a region in the housing wall wherein there is an aperture for receiving a test probe. The test terminal is in firm resilient engagement with a conductive component of the line circuit and the wall adjacent to the apertures whereby the test terminal is maintained in its desired position within the housing to avoid short circuits therein.

Abstract: A self-contained device to protect electrical appliances from damage or destruction caused by abnormal power surges due to lightening and other causes is plugged into any household electrical outlet and has a receptacle for the plug of the power cord leading to an appliance. The unitary device contains readily replaceable fuses directly in line with the appliance power line and the fuses are chosen to allow the appliance to receive the necessary power to operate while preventing it from receiving excessive damaging power. Extreme power surges due to lightening and the like are prevented from jumping the gap between the end terminals of blown fuses by following a grounding power stop clipped onto the fuse bodies near one pair of their end terminals and leading directly to a grounding conductor. The device is embodied in either a 110 v or 220 v configuration with two and three fuses respectively, and is also embodied in a television receiver protective arrangement.

Abstract: Overvoltage arrester having a gas-filled housing, including two overvoltage arrester electrodes disposed across from each other in the housing, a tubular insulator body spacing the overvoltage arrester electrodes apart from each other, a ring-shaped flange integral with one of the overvoltage arrester electrodes forming a first spark gap electrode, a ring-shaped metal cap forming a second spark gap electrode being superimposed on the first spark gap electrode and pressed in on the tubular insulator body, the first and second spark gap electrodes forming a spark gap having a given clearance therebetween, and a contact spring connecting the second spark gap electrode to the other of the overvoltage arrester electrodes.

Abstract: A replacement type gas tube protector for use with an older type telephone protector block utilizing a bayonet lug type engagement. The original carbon block protection is replaced by a gas tube element of smaller dimension, a conductive washer, and an insulative washer having a conductive sleeve. The conductive washer and gas tube element form a primary air gap means. The conductive washer and the insulative washer form a secondary air gap means.

Abstract: A protector module (30) for protecting tip and ring conductors of a telephone loop includes a pair of protector assemblies (40-40') which are supported within a common housing (32). A voltage protection subassembly (42) of each protector assembly is connected electrially to a grounding subassembly (44) for causing current associated with excessive voltage surges to be conducted to ground. Each protector assembly also includes a current protection subassembly (41) which comprises a dielectric base and a line pin (61) and a central office pin (57) with the line and central office pins being connected together electrically to establish electrical contact between a conductor of the circuit and its protector assembly. A shunting element (62) is disposed concentrically about the line pin and is releasably secured to one end of the line pin in an initial position by a fusible bonding material.

Abstract: A miniature surge protector for use in telephone central offices, or the like which are provided with terminal blocks for communication lines includes an in-line over-current coil arrangement which grounds each communication line if an overcurrent flows therethrough and is additionally provided with a gas tube surge protector and an auxiliary air gap disposed across a pair of communication lines and a common ground terminal, thus providing overvoltage and overcurrent protection to a pair of telephone communication lines.

Abstract: A line protector for central office use comprises an elongated housing open at one side for receiving components and a cover for the opening. First and second surge arresters are coaxially positioned within the housing. First and second line terminals are respectively connected to the arresters as is a common ground terminal. The three terminals project from one end of the housing in the provision of coplanar flat pins for plug-in connection with a circuit board edge connector. Means including a test contact in the housing permits use of a test probe to test the lines while the protector is plugged into the connector. A shiftable insulator in the housing is used optionally to interrupt the inside lines at the line terminal pins.

Abstract: A gas tube overvoltage protector has two opposed electrodes sealed in a tubular dielectric housing, the outer ends of the electrodes extending from the housing. The inner ends of the electrodes define a primary gap at sub-atmospheric pressure. The lower electrode has an extension of reduced diameter on its outer end. An auxiliary gap is formed by pushing on a metal cap over the lower end of the dielectric housing, with a thin flexible dielectric member between the cap and the outer end of the bottom electrode, the extension extending through the dielectric member and cap. One or more apertures in the thin dielectric member define the auxiliary gap, between metal cap and bottom electrode. A further feature is that the cage, within which the protector is positioned, has one or more legs preformed such that their lower ends are pushed into positive contact with the metal cap when assembled into a closed ended hollow cap for assembly into a protector block.

Abstract: An improved gas type telephone protector module in which the firing of a heat-sensitive means causes a slidably mounted ground plate to bypass in both circuits to the flow of excess current and/or voltage surges to ground. Means are incorporated to provide a secondary air gap which becomes operative upon the failure of either chamber of the gas tube.

Abstract: A clip-on device to protect telephones and communication apparatus, wherein clips for releasably holding a 3-terminal gas protector are external extensions of electrically insulated spaced terminals within the housing. A heat coil in series with each communication line and a carbon block air gap protector across each half of the gas protector for redundancy, are within the housing. The heat coil protects against a sustained overcurrent condition on the line while the gas and air gap protectors ground over-voltages of short duration. Utilizing heat conduction means, heat generated from sustained over-voltage melts a fusible disc allowing spring biased parts within the housing to move and short line terminals to ground.

Abstract: An electrical surge arrester module having a back-up external spark gap in its base assembly comprising an insulator plate perforated at points intermediate a terminal contact surface in said base assembly and a conductive plate at ground potential when said surge arrester module is in use.

Abstract: A clip-on device for use with an over-voltage protector to protect telephones and other sensitive apparatus. The device comprises a housing in which is disposed in electrically insulated spaced array, electrical contact means and heat conduction means. Each of these means have portion external to the housing which detachably grasps the over-voltage protector. Movable elements disposed within the housing include electrically insulating fusible spacers. The housing clips onto the over-voltage protector and engages the respective electrodes thereof. A sustained overload condition causes the fusible spacers to fuse whereupon the movable elements operate to short the electrical contact means to ground.

Abstract: A line protector has a housing with coaxial surge voltage arresters, line terminals and a ground terminal. One line terminal is substantially at one end of the cavity of the housing while the other line terminal extends substantially the full length of the cavity of the housing. The ground terminal extends from between the arresters to said one end of the housing cavity. Each terminal projects from the housing at said one end. The three terminals are insultated from the arresters by barrier walls in the housing. A cover closes a side opening in the housing through which the components of the protector are inserted.

Abstract: A surge voltage arrester assembly comprises a primary gas tube surge arrester and an air gap secondary arrester that provides surge protection should the gas tube become vented to atmosphere. The secondary arrester has the air gap defined by a rim of one of the gas tube electrodes and an opposed roughened surface of a metallic cup into which the gas tube is positioned. The roughened cup surface has a coating of graphite applied thereto. The electrode rim may or may not be roughened and/or coated. In a three element version of the invention wherein the gas tube has two line electrodes and a ground electrode, metallic cups are provided at opposite ends of the gas tube to cooperate with the ground electrode for forming secondary air gaps for each line electrode. The cup surfaces at the secondary air gaps are roughened and graphite coated. An O-ring seals each secondary air gap against the entrance of contaminants.

Abstract: A clip-on device to protect telephones and communication apparatus, wherein clips for releasably holding a 3-terminal gas protector are external extensions of electrically insulated spaced terminals within the housing. A heat coil in series with each communication line and a carbon block air gap protector across each half of the gas protector for redundancy, are within the housing. The heat coil protects against a sustained overcurrent condition on the line while the gas and air gap protectors ground over-voltages of short duration. Utilizing heat conduction means, heat generated from sustained over-voltage melts a fusible disc allowing spring biased parts within the housing to move and short line terminals to ground.

Abstract: A line protector has a gas tube surge arrester as a primary protector and an air gap as a secondary or back-up protector should the gas tube fail due to leakage. The secondary air gap is established by perforated plastic sheets which are interposed between a line terminal and a ground contact both of which are supported on an insulating base.

Abstract: An electrical protector device (10) for grounding excessive voltage and excessive current to safeguard telecommunications circuits includes a heat coil assembly (100) for sensing and directing excessive current to ground, and a spark gap arrester (200), axially aligned with the heat coil assembly (100), for sensing and controlling excessive voltage. Whenever an overcurrent condition is encountered, heat coil mechanism (110) is displaced to provide metallic contact of the incoming line to a ground structure (300). In addition, the device is adapted to provide protected testing of both incoming pairs and office equipment. Two test points (123) formed as part of the heat coil assembly (100) are in contact with the individual wires of the incoming line. These two test points are accessible through apertures (402) in the protector housing (400).

Abstract: Laminar air gap devices include two overlapping conductive layers separated by a non-metallic insulating layer. The insulating layer is perforated to provide at least one air gap between the conductive layers. The devices are positioned between a line electrode and ground electrode of a gas filled surge arrester and resiliently retained thereon by conductive clips. Non-metallic fusible elements, preferably plastic, are interposed between the clip legs and the associated electrode. The fusible element may also be the insulating layer between the conductive layers.

Abstract: A protection module for connecting blocks is intended notably for at least one line wire of a telephone system and comprises a case having a ground terminal, an input terminal and an output terminal for each line wire, and a first lightning arrester having a first terminal connected to the ground terminal and a second terminal clamped resiliently between two extensions of the line terminals, respectively. Another lightening arrester has a first terminal connected to the ground terminal and a second terminal clamped resiliently between two extensions of the other pair of line wire terminals. An orifice registering with a third pair of terminals parallel to the other pair of line wire terminals is adapted to guide a detachable element which comprises an insulating portion adapted to be fitted between the terminals of the third pair of the lightning arresters and each extension of the pair of output terminals.

Abstract: Gas filled surge arrester is equipped with a thermally responsive short circuit switch for overload protection and air gap shorting for back up overload protection. The switch and air gap device is disclosed in three orientations; namely, separate and external to the gas tube; unitized with the air gap interior to the switch; and unitized with the air gap exterior to the switch. The unitized arrangements have application in circuitry with gas tubes where back up air gap protection of the thermal switch is desired.

Abstract: A protector for a communications line comprises a three electrode gas tube surge voltage arrester as a primary protective device and metal oxide varistors as additional protective devices. In series with each side of the line, is an inductor that serves to isolate the gas tube from the varistors at relatively fast rise times of transient overvoltages. The gas tube, the varistors and the inductors are all mounted in a single housing that is divided into adjacent sections by an insulating member. The gas tube is in one section and the inductors and varistors are in the other section, the inductors being side-by-side and each coaxial with a pin that is adapted to be connected to the line.

Abstract: A surge voltage arrester utilizes for surge protection a varistor of the zinc oxide type between a line terminal and a ground terminal. The varistor is of a type that has a resistance which decreases as increasing voltage is applied thereacross. With increasing temperature the leakage current through the varistor increases at a given voltage. At a critical temperature and voltage condition, the varistor is subject to a thermal runaway condition which would cause the varistor to fail expelling hot particles. To avoid this failure condition, a fail-safe mechanism is provided which connects the line terminal to the ground terminal by-passing the varistor when there is an overcurrent condition on the line that results in heating of the varistor.

Abstract: A surge voltage arrester assembly comprises a primary gas tube surge arrester and an air gap secondary arrester that provides surge protection should the gas tube become vented to atmosphere. The secondary arrester has the air gap defined by a rim of one of the gas tube electrodes and a metallic cup into which the gas tube is positioned. In a three element version of the invention wherein the gas tube has two line electrodes and a ground electrode, metallic cups are provided at opposite ends of the gas tube to cooperate with the ground electrode for forming secondary air gaps for each line electrodes. An O-ring and a sealing compound seals each secondary air gap against the entrance of contaminants.

Abstract: An electrical protector assembly (100) for grounding excessive voltages and excessive currents encountered on a telecommunication line circuit includes a heat coil subassembly (103) for sensing the excessive currents and apparatus (102 and 104) axially aligned with the heat coil assembly for conducting the excessive voltages to ground. When excessive currents are encountered on the line circuit, the protector provides a direct metallic contact (151 and 102) between the line circuit and ground. The internal arrangement of the protector allows both carbon blocks (180 and 181) and gas tube protectors (196) to be used as excessive voltage protection devices. In addition, miniature electronic circuits, such as minibridge lifters (195), may be advantageously incorporated into the protector module.

Abstract: Disclosed herein are surge arrester configurations employing non-metallic and preferably plastic fusible elements which normally insulate biased short circuiting members from shorting the surge arrester but which, in the event of certain forms of excessive overloads, fuse to thereby permit the shorting elements to short circuit the arrester gap. In addition, the embodiments include integral backup air gaps to provide additional backup protection covering certain gas tube failure modes. In the illustrated embodiments, the shorting elements each take the form of a conductive clip with one set of spring fingers in electrical contact with the line (end) electrode and another set urged in the direction of the ground electrode but separated therefrom by an annular plastic fusible sleeve coaxially coupled to the center body housing.

Abstract: A connector assembly designed to be mounted on a telephone main distribution frame includes a connector base having a plurality of rows of channels formed on one face by ledges extending between elongated edges of the connector base, a ground plate having a conductive side and an insulating side and a plurality of pedestals. A first set of terminals extends through the pedestals, the ground plate and the connector base into the channels, and a second set of terminals extends through the pedestals, the ground plate and the connector base so as to project from the ledges such that the first and second sets of terminals maintain the connector base, ground plate and pedestals together.

Abstract: A line protector for a communications circuit provides overvoltage and overcurrent protection. The overvoltage protection is effected through an arrester that provides an arc gap from the line to ground. For overcurrent protection a fusible element is melted by a heat coil causing a conductive cup to move into engagement with a conductive plate that is connected to a line pin, thereby forming a direct metallic shunt to ground. The heat coil assembly, the line pins, and the contact plates associated with the line pins are mounted on a dielectric sub-base which in turn is supported by the base of the protector. The ends of the heat coil are welded to the contact plates and the line pins are staked to the contact plates, thereby eliminating noise-causing butt contact connections in the line circuit.

Abstract: A gas tube arrester protector used in protecting a pair of telephone lines from high voltages or surge currents includes a three electrode gas tube overvoltage arrester having a ground electrode adapted to be coupled to ground potential through a ground lead, a pair of line electrodes, each of which is adapted to be coupled to one of the pair of telephone lines through a terminal line or lead, a flat, generally U-shaped line contact and a fusible link coupled between the line contact and the line electrode. The gas tube arrester is positioned in an insulating housing or shell by disposing the line contact in slots formed by ribs on opposed walls of the housing and by positioning in grooves formed peripherally about an open end of the housing overlapped spacers having overlapping slots to receive the ground and terminal leads. The open end of the housing can be further sealed with an insulating material.

Abstract: An elongated line protector has a series of base modules for plug-in reception of a series of arrester modules, carbon or gas tube type as may be selected. Along opposed sides of the base modules are recesses for slide-on attachment of terminal modules each having a row of terminals, such as binding posts, connector clips, etc. for connections to telephone lines to be protected. Several groups of terminal modules may be assembled with each other side-by-side on each of the opposed base module sides depending upon the number of groups and styles of terminals desired. Correct electrical connections between the terminals and the arresters are established through the protector upon assembly by conductors including ground and line busses.

Abstract: A line protector for protecting telephone lines and the like from over-voltage or over-current conditions includes a primary arrester element and a secondary arrester element that provides back-up protection upon a fail open of the primary arrester element. The primary arrester comprises a gas tube having spaced electrodes to form an arc gap therebetween. The secondary arrester includes a pair of electrodes axially aligned with the gas tube and separated by an insulating spacer to provide an air gap therebetween. The air gap of the secondary arrester is maintained at a predetermined spacing such that the breakdown voltage thereof is greater than the rated breakdown voltage across the arc gap of the gas tube but less than the breakdown voltage across said arc gap should the gas tube fail open as by being vented to atmosphere.

Abstract: Disclosed herein is a three-element gas tube fail-safe station protector of known design modified to incorporate a back-up air gap system. To the ground terminal stud of the protector is added a lateral conductive member defining a pair of blade-shaped ground electrodes. To each of the line electrode terminal studs is added a conductive blade-shaped electrode which overlaps and is spaced from a respective one of the ground electrodes. The air gaps which are thus defined between ground and each line, i.e. paralleling the gas tube gaps, are encapsulated and dimensioned to provide back-up ionization in the event of a failure of the gas tube.

Abstract: A protector module for use in protecting telephone lines includes an insulating base with two sets of line pins and a ground pin extending from one side of the base. Disposed on the other side of the base is a pair of spaced apart line contacts with one of the line contacts being coupled to one set of line pins and the other line contact being coupled to the other set of line pins and a ground clip assembly coupled to the ground pin and disposed between the line contacts. The ground clip assembly mounts a three electrode gas tube arrester having a pair of line electrodes and a ground electrode such that one of the line contacts is coupled to one of the line electrodes by a fusible element and the other line contact is coupled to the other line electrode by another fusible element.

Abstract: A protector for telecommunications lines has an elongated housing with a ground bar extending up one side. End webs extend from the opposite ends of the ground bar across the housing, and a central web extends from the bar also across the housing. A protection device composed of an overcurrent device and an overvoltage device extends between each end web and the center web, the devices on a common axis. In a particular arrangement a ground spring is attached to the ground bar at the side of the housing for connecting with a suitable housing of a protector field in a connector unit. Detent means can be provided to provide for positive partial withdrawal of a protector.

Abstract: A telephone protector module utilizing a three element gas tube discharge device and having heat-actuated overload protection means causing both tip and ring circuits to be simultaneously grounded upon the occurrence of an overload.

Abstract: A protector module for use in mounting a gas tube arrester or carbon arrester assembly in a telephone central office protection system has an insulating base and a conductive case or cover. The base has a channel with a projecting stop on one side, in which channel is disposed a portion of a line contact. Another portion of the line contact extends through the base and is positioned against an upstanding wall located at one end on the other side of the base, in which side the gas tube arrester or carbon arrester assembly is disposed. The case is secured about the other side and the upstanding wall by a plurality of spherical projections on the base which lodge in holes in the case. When the case is so positioned on the base, a line electrode of the gas tube arrester or carbon arrester assembly makes electrical contact with the line contact and a ground electrode of the gas tube arrester or carbon arrester assembly is coupled to the case.

Abstract: Disclosed herein are gas tube arrestor configurations employing multiple-function fail-safe elements which coact with the gas tube arrestor to define both a fusible path for fail-safe shorting and grounding of the arrestor in the event of certain forms of excessive overloads, as well as ionization gaps to provide backup overvoltage protection in the event of gas tube failure. In the illustrated embodiments, annular fusible rings are coaxially coupled to the gas tube housing in such a way as to provide, when fused, a short circuit connection between electrodes, the fusible rings also including pole face sections for defining an ionizable gap which functions as a backup air gap protector should the gas tube fail, e.g. because of a gas leak.Novel modular arrangements embodying the foregoing for use in central office and residential applications are also illustrated.

Abstract: An improved telephone line protection device including means for grounding excessive currents and voltages. The disclosed embodiments include temperature actuated resilient means for shorting currents directly to a source of ground potential without passing such currents through the elements normally present for protecting against excessive voltage surges, which are damaged by carrying excessive currents.

Abstract: A line protector has an arrester through which overvoltages on the line of short duration are grounded. The arrester may be of the type having an arc gap sealed within a gas tube. For an overvoltage of longer duration, a pellet is melted causing a spring to close a circuit bypassing the gas tube and provide a direct metallic path from the line to ground. A secondary arc gap between opposed conductors separated by an insulating sleeve has an arc-over voltage that is greater than the normal arc-over voltage of the first-mentioned arc gap and provides a path to ground for short duration overvoltage conditions in the event of failure of the arrester. Excessive current across the secondary arc gap may melt the insulator sleeve and engage the opposed conductors for grounding purposes.