Abstract: The following specification describes a padlock adapter assembly comprising a pair of identical stamped plates each having a pair of spaced passages aligned with a respective passage in the other plate to form a pair of aligned passages for receiving a respective padlock shackle. A hook on one end of each plate is pivoted toward or away from the other hook about an axis through either pair of aligned passages when the respective one of two padlock shackles is removed to permit access to an enclosure.

Abstract: An electric receptacle for ordinary household or trade size junction boxes having a complete ground fault circuit interrupter incorporated in the receptacle, including electronic components to detect a ground fault on the load side of such receptacle, and a coil and trip mechanism which is actuated when a ground fault is detected. On occurrence of a ground fault, the coil and trip mechanism opens the protected circuit. Means to test the interrupting mechanism, means to indicate the interrupter contacts are open, means to reset after testing or occurrence of a ground fault, and means to provide an audible signal if improperly wired, are included.

Abstract: An apparatus for rejecting an improperly installed plug-on unit, including a circuit controlling device, in an electric power distribution and metering system having a box-like enclosure. A pair of supports are attached to opposing sides within the enclosure with top surfaces substantially parallel to the back of the enclosure so that the plug-on unit can be secured thereto. The circuit controlling device includes a circuit breaker with plug-on jaws, a receptacle and a neutral connector at one end of the plug-on unit which plugs into a jaw of a ground assembly on the back of the enclosure. A plurality of U-shaped interference brackets are welded across the width of the enclosure above the top surface of one support where the end of the plug-on unit containing the neutral connector must be mounted. Each bracket includes a 30.degree.

Abstract: A rotary tap changer or switch is rotated by a motor to a plurality of contactor positions by a control system having a cam that rotates to activate limit switches respectively corresponding to contactor positions. The activation of the limit switches causes operation of a relay which, after a selected time delay, operates to discharge a capacitor across the motor to apply dynamic braking and stop the motor. When starting the motor to rotate the tap changer, energization is applied through the limit switches to select rotation in a forward or reverse direction determined with some modification by the shortest distance of rotation to the new selected position.

Abstract: A current limiting circuit breaker having for each pole, a pair of main contacts separable upon operation of a thermally and electromagnetically operable tripping device and a pair of auxiliary contacts for current limiting in series with the main contacts and in parallel with a transformable resistor having a positive temperature coefficient of resistance. The auxiliary contacts are separable when an electromagnet is energized by a fault current which simultaneously energizes a field magnet to produce a transverse magnetic field across the auxiliary contacts and the arc formed between them when separating. This simultaneous action of electromagnet and field magnet coacting for rapid contact separation and lengthening of the arc upon flow of a fault current serves to increase arc voltage almost instantaneously to that of the source, about which time the fault current is totally shunted into the resistor.

Abstract: An iron wire resistor connected in shunt with the current limiting contacts of a circuit breaker. The current limiting contacts are in series with the main contacts of the breaker, and are separated by extremely high fault currents before the main contacts can respond. Opening of the limiting contacts shunts the high fault current through the resistor. The resistor has a positive temperature coefficient of resistance and heats rapidly to sharply reduce the magnitude of the high fault current.To prevent the connection between the resistor and a low resistance copper conductor from being destroyed by the high fault current an intermediate resistance value terminal of copper clad stainless steel is employed between the resistor and the copper conductor.

Abstract: A manually operated snap acting switch having contacts in a circuit connecting an electric source to an electric load. The switch has contacts operated by a toggle mechanism and includes elements and mechanisms for causing the levers of the toggle mechanism to move to a tripped position and the contacts of the switch to open whenever the current in the circuit exceeds a predetermined value or in event of a power failure of the source. The elements and mechanism causing the movement of the levers to the tripped position and an opening of the circuit in event the source has a power failure include a spring-biased lever, a solenoid, which is continuously energized by the source, and a latch which is moved to released position by the solenoid plunger when the solenoid is de-energized. The lever which causes the toggle levers to move to the tripped position is held in an inactive position by the latch and moves to an active position when the solenoid is de-energized and the latch is moved to its released position.

Abstract: A solid state relay structure for use with different alternating current motors having a range of full load current and service factor ratings. The relay includes a rectangular housing and bores extending through the housing through which conductors to the motor are passed. The rear end of the housing is spaced from the panel on which the relay is mounted so the conductors may be looped through the bores when portions of the looped conductors are passed in the space between the rear end of the relay and the panel. The solid state components of the relay are encapsulated in the interior of the housing and are connected to switches, terminals, and a light emitting diode located at the front of the housing so the relay may be easily programmed for use with motors having different ratings. The terminals and operating and test instructions, located at the front end of the relay, provide a convenient arrangement for wiring the relay in its control circuit and information to program the relay.

Abstract: A self-powered solid state overload relay having current transformers energized by current to a motor to be protected. The transformer has secondary windings connected through diodes to charge a capacitor in a circuit which senses the magnitude of motor current and capacitors in a trip-reset circuit which causes the circuit to be interrupted when the motor current exceeds a pre-programmed value. The diodes in capacitor charging circuits are poled so that the capacitor in the sensing circuit and the capacitor trip-reset circuit are charged by opposite polarity rectified half wave current pulses.

Abstract: An undervoltage trip coil and armature, with a pivotal member biased against and riding on the latch pin of the armature to sense its position. On occurrence of a low voltage condition, a trip lever causes the latch mechanism of the breaker to trip. The pivotal member then interferes with the latch and prevents reset. The undervoltage trip coil is normally energized to normally attract the undervoltage armature. On occurrence of a specified undervoltage condition the armature releases causing the trip lever to trip the latch mechanism and allowing the pivotal member to interfere with the latch of the breaker. During such condition, the breaker cannot be reset until the armature is attracted to the undervoltage coil under proper voltage condition.

Abstract: A circuit breaker of a medium voltage roll-in type is connected to an external control system by a plug and associated conductor line. The plug has a handle that is screwed into position to retain the plug in place and to compress a cable spring connected to a flexible cable enclosed in a tube. The compression of the cable spring enables a lever spring, acting oppositely to the cable spring, to move a lever attached to the cable. The lever is connected to move a trip latch that connects to a latch mechanism that opens and prevents closing of the circuit breaker.

Abstract: A trench duct system of the type embedded in concrete floors or the like is provided for use in the distribution of electrical power, service and/or communication cables and wiring throughout a building. The system includes a plurality of trench duct sections which are interconnected to form a predetermined distribution layout. Each section of duct includes a cover plate which is removably supported by a pair of vertically adjustable side rails. The length of the cover plate and the length of each supporting side rail may or may not be the same and will depend upon the particular layout. The exposed surface of the cover plate is flush with the plane of the finished floor. Adjoining side rails, when in angular relation to one another, are interconnected by coupling members or connectors which maintain the continuity and stability of the system.

Abstract: A self-powered solid state overload relay circuit having current transformers energized by conductors supplying current to a multiphase alternating current motor. The transformers have secondary windings connected to charge a capacitor with a voltage indicative of the magnitude of the maximum current in the motor windings. The circuit includes presetable impedance circuits which permit the circuit to be easily programmed to respond to a range of abnormal motor currents in the winding in motors of varying size and service factor ratings, components which are arranged to duplicate the operation of melting alloy and bimetal type overload relays in an automatic or in a trip-free manual reset mode, a light emitting device which visually indicates when the relay is in a tripped state, and components which cause the relay to be insensitive to ambient temperature variations.

Abstract: Lengths of lay-in ducts, each in the form of an open top trough having exterior connecting flanges at its ends, are connected together in end to end relation in a run by bolts passed through the flanges. Each trough is provided with a cover which terminates a slight distance short of the trough ends. A joint sealing device common to the adjacent end portions of two connected troughs provides a seal between the device itself and the tops of the adjacent end portions of the trough, between the end portions of the covers and their associated troughs, and between the adjacent end portions of the covers themselves. The device extends across the troughs, and has one end hingedly connected to a supporting bracket which, in turn, is clamped fixedly in position on one of the connected trough flanges by one of the connecting bolts connecting the flanges together.

Abstract: A captive fastener assembly, comprising a guide rail structure, a screw mounted thereon for linear movement relative to the guide rail structure but restrained from rotational movement, and a captive nut mounted in a cooperative bracket for rotational movement but restrained from linear movement relative to the bracket. The invention is particularly useful in fastening various work pieces together, such as an electric terminal box and a meter cabinet, the guide rail structure being mounted on one of the work pieces with the screw captively in place and the bracket secured to the other work piece with the nut captively mounted therein.

Abstract: A bus bar, for electrical switchboards comprises an elongated extruded imperforate metal bar of rectangular cross section having slots, with parallel side walls, extending the entire length thereof. Some of the slots are of T-shape cross section, each with the T-leg portion opening through a face of the bar. Others of the slots are rectangular grooves of generally uniform width, with smaller V-shaped grooves on opposite sides to accommodate threaded end portions of bolts or screws, and each opens through a face of the bar. T-bolts are arranged with their heads in, and slidable along, the full length of selected ones of said T-slots, respectively, to any desired position. The bolts have threaded stems, each of which extends from its associated head through the leg portion of the T-slot in which its head is disposed, and beyond that face of the bar through which the associated T-slot opens. Each stem is adapted to threadably receive a nut for clamping supporting or connecting brackets to the bar.

Abstract: A timing attachment for a relay which may be easily programmed to provide an ON delay or an OFF delay operation of a switch having either normally open or normally closed contacts. The attachment includes a pair of identical latch levers and a pair of identical levers which operate to reset a timing mechanism and cause the timer to operate in the OFF or ON delay modes. The timing mechanism includes a pair of relatively rotatable discs having flat contacting surfaces with one of the discs having a pair of dead-ended concentric grooves and the other disc having an elongated hole which connects the concentric grooves at selected positions along their lengths to provide a metering air duct having a length that varies from zero to the full length of both grooves to provide a minimum to maximum time delay timing operation.

Abstract: A removable cover assembly is provided for an electrical switch. The assembly includes a casing having an apertured panel, on the interior surface of which are mounted an illuminating means and elongated contact means, the latter making electrical contact with conductors of the switch when the cover assembly and the switch are in assembled relation. A lens piece is accommodated in the panel aperture and the illuminating means is secured to the portion of the lens piece adjacent the panel interior surface.

Abstract: The contact materials comprise silver with additions of mercury or mercury and tellurium and silver-cadmium oxide compositions with additions of mercury and tellurium. The methods of making the materials include the steps of adding a silver-mercury alloy to molten silver and to a molten silver-tellurium powder mixture. The materials including cadmium oxide are produced by heating a mixture of powders of silver, a cadmium-tellurium compound, cadmium oxide, and mercuric oxide powders in a reducing atmosphere and then reoxidizing.

Abstract: The contact materials comprise silver with additions of mercury or mercury and tellurium and silver-cadmium oxide compositions with additions of mercury and tellurium. The methods of making the materials include the steps of adding a silver-mercury alloy to molten silver and to a molten silver-tellurium powder mixture. The materials including cadmium oxide are produced by heating a mixture of powders of silver, a cadmium-tellurium compound, cadmium oxide, and mercuric oxide powders in a reducing atmosphere and then reoxidizing.