Abstract: Safety apparatus for indicating a live alternating current voltage condition in an insulated electrical conductor having a central conductor wire comprises: an electrically conductive external sheath extending along a predetermined length of the insulation forming with the central conductor wire a capacitive alternating current path across the insulation; and a signal generating circuit including a full-wave rectifier connected directly between the sheath and ground. A capacitor and a neon or other gas discharge bulb characterized by avalanche breakdown at a predetermined voltage are connected in parallel with the rectifier. Optionally, a piezo electric or other sound-generating device may be in series with the neon bulb. When the central conductor wire is energized at 1000 volts AC or above, the bulb flashes, and the optional sound generator activates, at a frequency dependent on the length of the external sheath along the insulation.

Abstract: Safety apparatus for indicating a live voltage condition in an insulated electrical conductor having insulation surrounding a central conductor wire, comprises: a layer of semi-conducting tape on the outer surface of the insulation; an electrically conductive sheath consisting of a plurality of turns of wire on the outer surface of the semi-conducting tape; a layer of stress-relieving tape wrapped about each end of the semi-conducting tape and an adjacent portion of the insulation; and an outer layer of electrical insulating tape covering all the previously-described tape layers and the turns of wire which are connected to ground through a fluorescent tube. When the insulated electrical conductor is subjected to live alternating current energization at 7000 volts or more, a capacitive alternating current path is established across the insulation, between the central conductor wire and the turns of wire acting as capacitor plates, to light the fluorescent tube.

Abstract: A high temperature pressure switch assembly for an explosion-proof enclosure used in hazardous atmospheres comprises an electrical control switch for a remote power source supplying electrical power to the enclosure, and a pressure responsive member which actuates the control switch to disconnect the power source in response to a small but abrupt pressure rise within the enclosure which indicates an explosion, severe electrical arcing or insulation pyrolysis therewithin.

Abstract: An isolation switch comprises a mounting plate with a hub adapted to extend forwardly through a wall of an explosion-proof enclosure. A shaft is journaled for axial movement in the hub. First and second stationary contact members are supported on the mounting plate. The first stationary contact member has input and output power contacts, and the second stationary contact member has first and second grounding contacts. Jumpers connect the output power contacts with the second set of grounding contacts. A moveable contact member is moveable by the shaft between a "closed" position connecting the input and output power contacts; and an "open and load-side-grounded" position disconnecting the input and output power contacts and connecting the output power contacts to ground through the grounding contacts. A handle assembly is eccentrically pivoted on the forward end of the shaft, is guided for forward and backward swinging movement, and has cam bosses guided for transverse movement relative to the shaft.

Abstract: Apparatus for cooling an electrical enclosure for use where headroom is limited. An imperforate top wall and a perforate ceiling wall below it define an exhaust compartment. The ceiling wall has openings above natural hot spots on heat-producing electrical components in the enclosure to receive heated air rising by convection. In one embodiment, louvered intake openings and internal baffles direct cool, external air to the bottom of the head-producing components. A fan draws heated air from the exhaust compartment and discharges it through a louvered orifice outside the enclosure, thereby augmenting the natural upflow of heated air by convection and preventing accumulation of heated air. In another embodiment, especially suited to dusty or corrosive environments, the electrical components are completely sealed, and clean inside cooling air is continuously recycled in a closed circuit between the heat-producing components and refrigerant-cooled heat-exchange apparatus.

Abstract: A control system for a booster type belt conveyor having one or more booster belts spaced at intervals along a conveyor belt with the upper, driving run of each booster belt frictionally engaging the underside of the conveyor belt carrying run. Each belt has a driving pulley connected to a driving unit including one or more electric motors, engageable and disengageable fluid couplings, and a gear box. The conveyor is for heavy duty service, in long lengths of several miles. There is an electrical control assembly for each drum or pulley driving unit. These automatically start the motors in sequence while the couplings are disengaged, each being started in response to a signal from a previously started motor that it has reached running speed. An electrical loop interconnects all the control assemblies and contains relays which, when the loop is energized to actuate the relays, cause the fluid couplings to engage.

Abstract: A reversing switch comprises a mounting plate assembly with a hub adapted to extend forwardly through a wall of an explosion proof enclosure. A shaft is journaled for both rotational and axial movement in the hub. A stationary contact assembly consists of a first set of four evenly circumferentially spaced contacts, each with a connecting terminal, mounted on an insulator base. A movable contact assembly consists of a second set of four evenly circumferentially spaced contacts mounted on an electrical insulating member connected to the shaft. Adjacent pairs of the movable contacts are interconnected. The shaft has an external handle with a unique cam and rotatable eccentric pivot connection for moving the shaft axially to engage or disengage the contacts when the handle is pivoted forward and backward a half turn, and for rotating the shaft to reverse the contacts when the handle is rotated a quarter turn.