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 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 line protector and associated termination structure comprises a module having printed circuit board wiring internally thereof and also as outwardly projecting contacts adapted for connection to a printed circuit board edge connector. An insulator is disposed against the printed circuit board and is slidable therealong and optionally serves to interrupt the tip in and ring in sides of the telephone line when it is desired to place the protector module in the so-called "detent" position. The protector module may be restored to its normal operating condition by retracting the insulator or by removing the module entirely from its position in the connector and then reinserting the module fully into the connector. This latter operation automatically slides the insulator to its non-detent position.

Abstract: A telephone main distribution frame connector assembly in which internal hand wiring is eliminated comprises a field of terminals for terminating incoming telephone line pairs and another field for terminating inside plant equipment lines, a field of terminals for terminating incoming lines, and a plurality of spaced parallel printed circuit boards for providing connections between the two fields of terminals. A series of spaced parallel ground busses run perpendicular to the circuit boards. The circuit boards have edge regions that are straddled by line terminal pins of overvoltage arresters for protecting the lines, which arresters also have ground terminal pins that engage the grounds busses between the circuit boards. Bezels at the first mentioned fields and an adjacent test field, along with bezels at the edge regions, aid in supporting the circuit boards.

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 line protector for a communications circuit provides a gas tube surge voltage arrester for primary surge protection and a back up air gap arrester for secondary protection in the event of venting of the gas tube. The gas tube is housed in a metallic tubular element that forms one electrode at the air gap, the other electrode at the air gap be provided by the rim of one of the gas tube electrodes. The tubular element is initially formed of circular cross section, then deformed to an oval cross section to be dimensioned to provide engagements across the minor diameter of the oval with the gas tube when the latter is telescoped therewith. The fit provided by the aforesaid engagement establishes the correct air gap width.

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: 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 line protector for a communications circuit comprises an insulating base having a ground pin and two pairs of line pins, one pair for each side of the line, projecting through the base. Each pair of line pins has a contact electrically connected thereto and projecting away from the base. The ground pin also has a contact projecting away from the base and spaced from the line pin contacts. A metal oxide varistor having opposed faces provides surge voltage protection for each side of the line. The line pin contacts are bonded to one face of the varistor while the ground pin contact is bonded to the other face of the varistor. Electrically conductive spring clips span the varistor and are pressed toward its opposite faces and in electrical contact with the ground pin contact. An insulating sheet is interposed between the clips and the line pin contacts to prevent one or more of the clips from grounding the line except in such surge condition that heats the varistor sufficiently to melt the insulation.

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: 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 includes a body having first and second end terminals and an intermediate terminal for connection to a ground potential. End caps are mounted on the end terminals and have peripheral edges maintained spaced from the intermediate terminal by means of a displaceable element responsive to excessive currents in the line being protected. High currents will cause the end caps to move toward the intermediate terminal and provide a short circuit therewith to ground to protect telephone equipment connected thereto. The intermediate terminal is mounted in a clip which has centering means formed therein to maintain the mechanical and electrical spacing of the intermediate terminal with respect to the end caps equal to one another. The protector assembly is mounted with a standard housing and base structure to be interchangeable with existing central office plug-in protectors.