Abstract: A safe electrical receptacle has internal switches to connect the power source to female connector elements when plug blades are inserted through openings in the receptacle cover. A blade inserted through one opening closes the switch to energize the female element behind the other opening. Slidable switch operators are disposed between the receptacle housing cover and the female elements and are moved laterally to close the switches before the plug blades engage the female elements.

Abstract: A section insulator for insulating adjacent sections of contact wire of overhead power supply systems for electrified railway lines and the like is disclosed. The section insulator is interposed between separated ends of adjacent sections of contact wire. Rigid strain plates are secured to the opposed ends of the sections and a strain insulator is secured to the strain plates above the level of the contact wires to maintain the required tension in the contact wires. Spaced runners supported by the strain insulator extend between the contact wires, there being air gaps between the ends of the contact wires and the runners. A pair of diverging glider arms is secured to each contact wire section adjacent its end. The glider arms extend toward each other beyond the ends of the contact wire sections and overlap the ends of the runners, there being transverse air gaps between the diverging glider arms and the runners.

Abstract: A non-rigid mechanical coupling for coupling a head assembly of a feed-through fitting to a slotted wiring conduit inserted in an opening formed in the floor of a building, wherein an apertured conduit flange is provided with plural tabs extending radially inwardly into plural slots formed in a common transverse plane in the conduit such that the conduit flange tabs are loosely retained in the conduit slots to provide a non-rigid mechanical connection therebetween.

Abstract: The male portion of a connector assembly of the locking type has blades insertable into slots in the mating female portion, the male portion then being rotatable to lock the blades against direct axial extraction. A spring urged locking pin adjacent the trailing edge of at least one blade normally protrudes from the connector face, is pushed in by the female face, and then protrudes after locking rotation, entering the slot portion vacated by the trailing edge. A rotatable sleeve on the male connector body has a cam surface which, upon rotation of the sleeve in the unlocking direction, first retracts the locking pin, then engages the body of the connector to rotate the blades out of their locked position.

Abstract: Disclosed is a female contact of unitary construction employing a torsion bar joined at one end to one of two opposing, spaced apart, elongated contact blades. The two blades have a relatively high spring rate and are forced apart when a male contact is inserted between the blades to provide the desired contact retention forces. One of the two contact blades is oriented edgewise with respect to the plane of a rigid opposing blade to provide a high spring rate in the direction of outward displacement. The outward displacement of the edgewise-oriented blade and hence the contact pressures applied thereby to the male contact are primarily a function of the torsional characteristics of the torsion bar to which it is joined. If desired, this contact pressure may be essentially doubled by providing two juxtaposed edgewise-oriented contact blades, each joined to a respective torsion bar.

Abstract: There is disclosed an elastomeric dielectric composition with very low dielectric loss factor which consists essentially of 100 parts by weight of an ethylene-propylene elastomer, from 0.25 to 1 part by weight of a vinyl silane, from 0.1 to 2 parts by weight of lead peroxide, up to 40 parts by weight of zinc oxide, from 1.5 to 4 parts by weight of a peroxide curing agent and an effective amount of inhibitor for said peroxide curing agent.

Abstract: An interlock arrangement is disclosed for a unitary molded enclosure for electrical terminals such as for the terminals for a dead-front electrical plug. The enclosure is formed of electrically insulating material and has an interior chamber for housing the terminals and additionally has at least one moveable wall portion connected to the remainder of the enclosure by an integral web hinge. The moveable wall portion pivots on the hinge to an open position which provides access to the interior chamber of the enclosure. A number of interengaging locking members are integrally formed with the moveable wall and the remainder of the enclosure and engage one another when the moveable wall portion is closed to relieve stress on the hinge when assembling and using the enclosure and to provide safety even if the web hinge is weakened or fails. The unitary molded enclosure may have two such moveable walls, each with its own web hinge and interengaging locking members.

Abstract: An integrally molded housing has a dead-front base and a pair of side covers pivotally connected to it by web hinges. The side covers fold about the web hinges to: (i) force cord conductors into insulation displacement terminals affixed to the housing and thus wire the connector; (ii) safely enclose the wiring area; and (iii) lock the side covers to the dead-front base by the engagement of mating portions of the covers and base to prevent relative motion even should the web hinges fail. The connector can have male or female contacts or both. It provides speed and convenience of wiring and assembly and ensures quality wiring by eliminating the variability in workmanship associated with conventional stripping of conductor ends and screw tightening used for screw type terminals.

Abstract: A female contact has at least one contact arm with an outwardly diverging tip end for guiding the tip of a male blade inserted into the contact. A contact arm abutment is mounted on a contact chamber sidewall and projects inwardly into the chamber. The abutment is aligned with an elongated contact arm of the female contact and is spaced outwardly from that arm to set the limit of acceptable outward contact arm deflection. A portion of the contact arm extending rearwardly from the diverging tip end is channeled to allow this end to clear the abutment when the contact is inserted longitudinally into the chamber from the rearward end thereof. The abutment limits outward displacement of the contact arm to prevent the overstressing of the arm by an engaging male blade and in a preferred embodiment, is formed as a unitary part of the pocket sidewall.

Abstract: A section insulator for insulating adjacent sections of contact wire of overhead power supply systems for electrified railway lines and the like is disclosed. The section insulator is interposed between separated ends of adjacent sections of contact wire. Strain plates are secured to the opposed ends of the sections and a strain insulator is secured to the strain plates above the level of the contact wires to maintain the tension in the contact wires. Spaced runners supported by the strain insulator extend between the contact wires, there being air gaps between the ends of the contact wires and the runners. A pair of diverging glider arms is secured to each contact wire section adjacent its end. The glider arms extend toward each other beyond the ends of the contact wire sections and overlap the ends of the runners, there being transverse air gaps between the diverging glider arms and the runners.

Abstract: A telephone network protective coupler for connecting terminal equipment to a telephone central office by means of a telephone line. The coupler includes two hybrid circuits which are interconnected to form a transmitting path and a receiving path. A power limiter in the transmitting path can be programmed remotely by selection of an external programming resistor without the direct introduction of noise into the transmitting path. The programming feature permits the gain of the transmitting portion of the device to be varied in steps from 0 to -12dB., and the maximum power output to be varied correspondingly in steps from 0 to -12 dBm. in order to arrive at an optimum signal power level of -12dBm. at the central office. The power limiter includes a controller gain amplifier for varying the attenuation of the transmitting path to a.c. signals, a remotely adjustable attenuator connected to a d.c.

Abstract: Disclosed is a lift cover assembly which effectively shields and seals an electrical installation box having an electrical wiring device mounted therein against the entry of rain or other liquid sprays whether the lift cover is in a raised or in a closed position. With the lift cover in the raised position, the assembly also functions to shield the interface between intercoupled wiring devices. The assembly employs a unique, elastomeric member of overall substantially annular shape which is compressible and extendable upon the closing and opening, respectively, of the lift cover to accomplish these functions without sacrificing the narrow profile of the assembly.

Abstract: Two separate but identically shaped sections cooperate to form an electrical cord gripping device when they are brought together. The sections are insertable into recesses in cooperating halves of an electrical housing, by wedging or snapping them into place, and, when the housing is closed, the sections form a restricted opening and provide a clamp around an electrical cord passing through the opening and into the housing. The sections are readily removable from the housing, so that a single housing can be used with electrical cords of different sizes. Further, each section contains a diagonal rib, and, when the sections are brought together, their ribs criss-cross one another to grip the cord from opposite sides. The sections are also shaped to provide abutting surfaces which overlap each other to cam the sheathing of the electrical cord into the opening provided by the sections, and prevent crimping of the sheathing.

Abstract: Disclosed is a device and method for attaching a lamp ballast to a mounting plate in a luminaire. The attachment device comprises an essentially closed eyelet at one end thereof and a straight shank at the other end thereof. The shank is insertable into a bore drilled transversely through the ballast by the ballast manufacturer for receiving conventional ballast mounting bolts. The eyelet end of the instant device receives a fastening member which is fixedly attachable to the mounting plate through mounting holes. In accordance with one aspect of this invention, pairs of such devices are mounted in opposition with their shanks inserted coaxially into opposite ends of the ballast bore to effect the attachment. The method of this invention involves forming a matrix of prelocated mounting holes for the devices to allow the attachment of different sized ballasts to the mounting plate.

Abstract: An interface unit for a four wire telephone circuit includes an echo suppressor. A filter circuit is connected to the transmit line drop side to detect voice and SF signals and to selectively couple a regenerated SF signal and the voice signal to the line side of the transmit line. A passive filter is selectively coupled to the receive side to attentuate voice echo but bypass SF signals.

Abstract: A transmission line having a fixed characteristic impedance, e.g., 600 ohms, is coupled to a receiver through an input transformer working into a very small impedance, e.g., 10 ohms or less. As compared to a conventional arrangement, where an input transformer works into a load nearly as high as the characteristic impedance of the line, the new arrangement has considerably better low frequency response and delay distortion characteristics. The new arrangement permits a much smaller transformer to be used if desired while retaining favorable low frequency response and delay distortion characteristics.

Abstract: Disclosed is circuitry interfacing telephone branch or trunk lines to provide D.C. driving voltages in response to, for example, on-hook and off-hook signals from a telephone set. The disclosed circuitry employs both lines to transmit useful signalling information to achieve, substantially, a doubling of the line voltage and a reduction of the common-mode burden on a differential voltage comparator for sensing the signalling information. These results are obtained with lower power dissipation than prior art systems.

Abstract: Disclosed is a system for monitoring the resistance in the pilot and ground conductors of a power cable and for interrupting power if the resistance exceeds a predetermined limit established for the particular cable. Novel circuit arrangements are employed to reset and calibrate the system.

Abstract: A terminal connection which will accept electrical conductors of various sizes and provides oxide breaking, spring loading, and conductor confining and bundling features. A tab or finger on one of the terminal elements presses the conductor regardless of its size toward the other terminal element, and oxide breaking edges on one of the elements break oxide coatings on the conductor while the tab or finger both confines the conductor and forces it toward a mechanical operator such as a screw. Forcing the conductor toward the screw reduces offset loading and permits additional oxide breaking by scraping the conductor with the screw as the screw is rotated to tighten the terminal. In the case of a stranded conductor, the bundling obtained by forcing the conductor toward the screw assures good interstrand electrical contact, so that the electrical resistance at the connection is not significantly different from the resistance of a corresponding solid conductor.

Abstract: Apparatus for providing a reliable grounding path between electrical fixtures and their mounting boxes, particularly where modifications to the conventional nature of the electrical fixtures are unnecessary. A metal clip is disposed as a conductive interface between the mounting yoke of the electrical fixture and the mounting screw utilized to secure the electrical fixture within the mounting box. Low resistance electrical contacts are maintained by disposing spring members on the clip to exert continual contact pressure against both the mounting yoke and the mounting screw. Sharp protrusions extend from the clip to concentrate the contact pressure exerted against the mounting yoke and the mounting screw is engaged by a screw-receiving means on the clip. A spring means is disposed within the screw receiving means to develop the contact pressure and also provides for self-adjustabliity to pitch variations of the mounting screws or to fixed pitch references of the mounting box.