Abstract: Monitoring of trigger circuits of power switches of electrical power supply devices which can experience faults due to breakage of conductors, oxidation of contacts, loosened terminal contacts, short circuits in trigger coils, etc. In order to improve fault monitoring, oscillator oscillations are applied to the trigger circuit of a power switch and are monitored. A fault- or alarm signal is generated in response to a detuning of an oscillator when the detuning persists for a predetermined time. The inductance of the circuit-breaking coil of the power switch serves as a frequency-determining element of the oscillator. A lag element with a delay of 500 ms is inserted after the oscillator. If the oscillator stays detuned for more than 500 ms, a Schmitt trigger is triggered by the lag element, whereby an alarm relay is actuated which switches on an alarm device via an alarm relay contact.

Abstract: A detector/annunciator circuit for monitoring the status (opened or closed) of field process switches. A two lead "End of Line Device" (ELD) is field mounted proximate the switch, and, during normal operation, detects switch status and transmits this information to panel mounted logic that decodes and annunciates the information. If the ELD's lead wires become open or short circuited, or are subjected to a ground fault, the panel mounted logic can identify the fault, diagnose its type, and annunciate such, thus aiding system troubleshooters.

Abstract: A switch for providing a safety function when its main contacts are fused or stuck together in the "ON" position, comprising a housing containing a pair of main contacts, one being designated an ON contact, and the other main contact being carried by a movable switch arm in the housing. This switch arm has a first end which carries the movable main contact and a second end, and spring means mechanically coupled to the movable switch arm normally bias the movable main contact toward open position away from engagement with the ON contact. Switch operating means including movable actuator means overcome the biasing force of the spring means for moving the movable main contact to closed position into engagement with the ON main contact.

Abstract: A power control and diagnostic arrangement illustratively embodied in an electric range having multiple surface heating units which are selectively coupled to an AC power supply by commutated relay switching circuitry. The commutated relay switching circuitry includes two switching networks. Each network includes a diode commutated master relay serially connected to a pair of pilot relays. Each pilot relay is serially connected to one of the surface units. Timing and control circuitry periodically interrupts operation of the power circuit in a normal mode to operate in a diagnostic mode. In the diagnostic mode the relays are switched in a predetermined sequence to test for a short circuit failure of the master relays or commutated diodes, an open circuit failure of the diodes, an open circuit failure of the master relays, a short circuit failure of the pilot relays and an open circuit failure of any individual pilot relay.

Abstract: The monitoring device simultaneously senses the voltage at the interconnection points between a plurality of series connected current interrupting devices. When current is interrupted by any one of the devices, the conductivity statuses of all devices are latched and stored until reset in a storage device which provides a signal indicating which of the devices caused current flow to be interrupted. The monitoring device thus detects both intermittent and sustained faults. The monitoring device employs optically isolated digital electronic circuitry for direct interconnection with AC control circuits.

Abstract: A high voltage current interrupter has integral therewith a fiber optic cable extending into the housing for carrying a failure-indication signal back to a remote monitor station when current flow through the interrupter is interrupted. In the preferred embodiment described herein, the optical cable extends continuously between optical input and output ports of the current interrupter and carries a monitor signal which is continuously present during normal operation. When a fault current occurs, the cable is explosively severed to interrupt the monitor signal and thereby provide a fault indication signal to the monitoring station.

Abstract: The invention relates to a circuit for indicating faults in a current consuming load connected to an electronic switching device by means of an indicator device wherein the input of the electronic switching device receives a signal via a control line to cause the load to be switched on. The problem of reducing the number of lines leading to a central operating location is solved in that the input resistance of the electronic switching device is made to be variable by means of an impedance which is controlled by an error signal and the indicator device is actuated in dependence on the current flowing in the control line and emits a fault indication if the current in the control line deviates from the value which it has when there is no fault.

Abstract: An electrical interlock to prevent unauthorized access to potentially hazardous equipment and an associated detection circuit to detect if a safety shield or closure member is open, not securely closed or has been tampered with and to thereupon automatically de-energize the equipment. The detection circuit may comprise a balanced bridge incorporating the electrical interlock into a leg thereof and may also provide a visual or audible indication whenever the bridge is unbalanced thereby indicating an improperly closed safety shield.

Abstract: Apparatus suitable for use with an operative system for monitoring the operational state of at least one system component such as a valve, which can adopt three possible states. The apparatus includes a state signal generator for operative association with the component and is responsive to the state of the component. The apparatus generates a first steady state signal whenever the component is in first state, a second steady state signal when the component is in a second state and a time varying signal such as a square wave when the component is in a third state.

Abstract: A smoke detector indicator for a fire alarm system having an ON-OFF switch indicator system that permits the audio alarm to be turned off for false alarm situations, but has a visual indication that the system is not in operation. In a system including a circuit connecting a smoke detector, battery and an audio alarm, all in a single enclosure, the improvement comprises a switch in the circuit to open the circuit and prevent the alarm from sounding, and a visual indicator associated with the switch, visually apparent when the circuit is open, and not visually apparent when the circuit is closed.

Abstract: The subject of the invention is a circuit for monitoring the charge state of a battery for supplying voltage to an electrical consumer through a mode selector switch which may be switched from an OFF-state for disconnecting the electrical consumer from the battery into an ON-state for connecting the electrical consumer with said battery whereby in said ON-state different modes of operation of said electrical consumer are possible. The charge state of the battery is determined when the mode selector switch is in the ON-state and, when the voltage drops below an adjustable threshold value, an acoustic and/or optical indication is triggered after the electrical consumer is switched off. The circuit in the ON-state consumes only a very slight amount of energy and no additional energy in the OFF-state. In addition to the mode selector switch for switching the electrical consumer on and off, no battery test button or additional battery test position of the mode selector switch is required.

Abstract: A vacuum monitor for a vacuum interrupter which can detect poor vacuum pressure at high detection sensitivity from the outside of the interrupter, on the basis of the impulsive electromagnetic wave signals generated when vacuum pressure increases within the vacuum interrupter. The vacuum monitor according to the present invention comprises, in particular, a detector terminal of capacitor coupler type or inductor coupler type disposed near a high voltage conductor for receiving impulsive electromagnetic wave signals, a signal level discriminating section, and a diagnosis section for improving the reliability of the monitor, particularly when the detected signal level of the electromagnetic wave signals is low.

Abstract: An abnormally high vacuum pressure of a vacuum interrupter is detected from outside of the interrupter in response to electromagnetic wave signals generated by an electric discharge derived in response to a voltage difference and depending upon Paschen's law. Since the above-mentioned electric discharge is quite different from so-called partial discharge, even when the fixed and movable contacts are closed (i.e., under hot-line condition), it is possible to detect poor vacuum pressure on the basis of the electric discharge existing between the fixed and movable contact rods including two contacts and the main shield, as well as when the two contacts are open. The vacuum monitor according to the present invention comprises a rod or loop antenna fixedly or movably disposed near a conductive material of or connected to the vacuum interrupter and a detection section including, in particular, a 2 to 20 KHz band-pass filter.

Abstract: In a means for detecting the wear of a current interrupting contact (4) there is used a light conductor (12) as a connecting link between the contact (4) and a detector (20) arranged at ground potential. The light conductor is inserted into an aperture (11) provided from the rear side of the contact, the bottom of said aperture being positioned at the level corresponding to a worn out contact. When the wear has grown so great that the light conductor (12) is exposed, the light or heat of the breaking arc will generate or interrupt a light signal, which via the light conductor is transmitted to the detector.

Abstract: An alarm device for a circuit breaker box is provided that is especially designed for mounting on the face panel of conventional breaker boxes. The alarm device includes an audible signaling device and a switch box having a plurality of switches arranged in parallel electrical relationship for selectively coupling the audible signaling device to a source of operating power. The switch box includes a pair of spaced apart, apertured sidewalls for mounting the switches in side-by-side pairs of opposed switch members. A spring is interposed between each pair of switch members for urging the switch member pairs away from each other and into abutting relationship with electrical contacts carried by the sidewalls. In operation, the switch box is mounted between the vertical rows of breaker arm toggle switches of a conventional circuit breaker box.

Abstract: An energization indicator lamp for time switch in which a two-color light emission element which can be switched from either color to the other color is used in place of a conventional energization indicator lamp, and a color of light emitted from the two-color light emission element is automatically switched in response to supply voltage, whereby the presence of energization upon the time switch as well as a value of the supply voltage can easily and correctly be recognized.

Abstract: An indicator is provided for each of a number of preselected conditions and is actuated in response to the occurrence of the corresponding condition. The indicator remains actuated until manually reset even if the triggering condition no longer exists.

Abstract: In the particular embodiments described in the specification a device is provided to protect against failure of a switch connected to a load and to give an alarm that the switch has failed. The device includes a circuit in parallel with the switch which contains a transistor and a diode to cause such voltage drop in the circuit as to prevent current flowing through a second diode when the switch is closed. If the switch fails open, the potential at the load side of the switch will drop, and the second diode will allow current to flow to the load through the circuit. The current flow produces a potential difference across the first diode to turn on another transistor to cause an alarm to be given. The device may be used to test such switches without affecting the load controlled by the switch.

Abstract: An electronic system for a high amperage molded case circuit breaker employing a voltage to frequency converter circuit for transforming fault current levels to a number of pulses corresponding to the fault level. The pulses are applied to a long time delay and short time delay circuit respectively which integrates the pulses to provide an output in a time period inversely proportional to the fault level. The long time circuit is provided with a second stage activated for a selected time by each output of the respective first stage to further count the pulses and provide a long time delay output in a time period inversely proportional to the square of the fault current. A variable resistance power supply provides a fixed voltage drop across the current transformer output to facilitate changes in breaker rating with a simple rating resistor change. A bimetal switch is also employed to sense the temperature adjacent the breaker contacts.

Abstract: In high voltage vacuum interrupters and similar devices, it is desirable to provide some indication that vacuum conditions within the containment vessel have degraded . Advantage is taken of the fact that metallic barium forms a substantially opaque and reflective film but that barium oxide, formed as a result of air penetrating the vacuum, forms a nonreflective and substantially transparent film. In the present invention, a housing is provided with means for attachment to the vacuum vessel with the housing having at least one light-transmissive portion. A barium film is disposed on at least one of these light-transmissive portions and means for detecting changes in the optical characteristics of the barium film are also provided. In this way, degradation in vacuum condition, evidenced by oxidation of the barium film, results in a signal indicating that contamination of the vacuum condition has occurred.

Abstract: The identification of the last-actuated of a plurality of parallel connected switches is provided by energizing a light source associated with the last-actuated switch and by providing a coded output signal which identifies the switch. The identification of a closed switch is accomplished through the use of logic circuitry which periodically imposes a potential difference across all of the switch associated light sources. The potential difference is sensed via the closed switch and functions as an initiation signal which causes generation of a coded output signal and maintains energization of the light source.

Abstract: A warning feature for a high voltage controller or the like. A lamp is mounted on the controller cabinet, and connected to an interlock circuit so as to be illuminated whenever line voltage is being supplied to a contactor assembly, regardless of the open or closed status of the contactor itself.

Abstract: An add-on fault indicator comprising a magnetic reed switch (22) and a lamp (24) connected in series across relay contacts (10, 12, 14) with the reed switch mounted by a clamp (34) contiguous to the outer surface of the metal coil shell (6) so as to be closed by the magnetic field when the coil (2) is energized. A normal operation indicator lamp (26) is connected in series with the relay contacts to indicate closure of the latter to energize a load (20). Fault indicator lamp (24) lights if the contacts do not close when the coil is energized but is shunted by the contacts to remain unlighted when the contacts close properly.

Abstract: An apparatus is provided for sensing the state of high voltage contact inputs in a process control system. Lower voltage contact closure input modules cooperate with a reference bus and reference bus regulator to reduce the voltage drop across an input module when a pair of contacts is closed, thereby reducing the energy dissipated and heat created by the input module.

Abstract: Trip indicator electromagnets of the permanent magnet type for use in a high amperage molded case circuit breaker under control of the long time delay and the short time delay or instantaneous circuits respectively for indicating the nature of a fault current and which can be reset by operating a viewing window that renders the indicator visible in response to armature movement.

Abstract: In a monitoring system for the gates of a mine lift shaft, each gate has a switch and a square wave is generated in a signal station and connected to a transistor inverter beyond each switch. When the switch is in the closed (safe) position, the transistor inverter is connected in circuit and the inverse of the waveform is transmitted back to the signal station. When the switch opens the transistor is shorted out and thus the returned waveform is in phase with the transmitted waveform. The various conditions which may be received at the signal station are detected and only if the switch and cable are operating correctly is the gate closed condition indicated. The use of a square wave and a changeover switch ensure that both conditions of the switch produce a definite signal at the signal station, thus any failure in the cable or switch prevents the received waveform from being the inverse of the transmitted waveform.

Abstract: A signalling system to indicate the position of a disconnect switch used in an electric transmission line. The switch has at least one moving contact and at least one fixed contact. The system comprises two transmitters associated with the moving and fixed contacts to transmit at least one ultrasonic signal indicating the position of the moving contact with relation to the fixed contact of the disconnect switch. A receiver assembly receives the ultrasonic signal transmitted by the transmitters and generates an output signal representative of the position of the moving and fixed contacts.

Abstract: In a circuit protector or the like a handle and a case from which said handle extends. Within the handle is an electrical lamp. A first pair of terminals is secured to the handle and to the lamp and a second pair of terminals is carried by the case. Electrical leads extend from the second pair of terminals to a pair of springs and the springs have end portions engageable with the first pair of terminals. The springs carried by a projection of the case and the end portions rest upon a boss formed on the case. The first pair of terminals press upon the end portions to close the circuit to the lamp.

Abstract: A circuit coupled between an indicating pushbutton panel switch and a software-programmable processor permits program control over the effect of switch actuation and over the illumination of the indicators. The processor can disable the switch function, blanking the indicators; it can accept a manual actuation of the switch, changing the illumination; it can reject as invalid a switch actuation within a multiple-switch field, retaining the current illumination; and it can alter the illumination in the absence of switch actuation. In one embodiment the signals providing the switch and indicator status are channeled into a serial data stream and transferred to the processor input register.

Abstract: A switch circuit arrangement, wherein a plurality of switch means each comprising paired display lamp and self-restore type switch contact are provided, and a control circuit is also provided in association with said switch means. By actuating any one of the switches, a display lamp paired therewith is lit, and at the same time, a control signal is derived from a detector circuit including I.sup.2 L element. The control signal thus derived is passed to a controlled device, whereby the display lamp is lit and maintained in the lit state.

Abstract: An apparatus for detecting the remaining amount of rolled paper, the diameter of which decreases as it is unrolled, comprises a detection lever which is swingable in a manner such that its free end is always in contact with the decreasing outer diameter of the roller paper. The detection lever includes a magnet piece which actuates a magnetism sensor for actuating an alarm device indicating the time for exchanging the roller paper when the diameter of the paper roll decreases to a predetermined diameter.

Abstract: A contact detecting apparatus for detecting the contact of a workpiece with a tool in a machine tool which includes a magnetic coil mounted on the periphery of a spindle head and connected to an AC power source for generating an induced current in a looped secondary circuit including the workpiece, a work table, a machine body, a spindle head, a tool spindle and the tool, when the workpiece and the tool are moved relatively into contact with each other. A first conductive wire forming a secondary winding of one turn is arranged in a parallel relationship with the looped secondary circuit and a current induced therein by energization of the magnetic coil. A second conductive wire is connected at one end thereof to the looped secondary circuit. A detecting device is connected to the first and second conductive wires for detecting contact between the workpiece and the tool based on the voltage induced across the first and second conductive wires.

Abstract: In an impact printer or the like having a plurality of print-hammer drive electromagnets which are respectively connected in series with switching transistors between the terminals of a voltage source, the switching transistors are normally gated into conduction by gating signals with a duration sufficient to energize the electromagnets for operating the associated print hammers. In a test mode which occurs prior to the operation of the printer, the gating signals are successively applied to the switching transistors and the duration of each gating signal is reduced so that the gated transistor remains conductive for a short interval which is insufficient to operate the hammer.

Abstract: For determining the position of a switch and for monitoring the connecting line for short circuits and interruptions, threshold stages containing Zener diodes are provided. A voltage or a current having periodically changing amplitude, preferably a triangular waveform, is fed to the switch via the line being monitored. The threshold voltages of the Zener diodes may be equal or staggered, depending on the manner of connection of the diodes in the circuit. For instance, if a Zener diode is connected in series with the switch, which may be either make contact or break contact and a Zener diode is shunted across the switch, Zener diodes with the same threshold voltage are used.

Abstract: An emergency evacuation path marking system employing a series of devices, each device having the tactile characteristics of shape and surface contacts, in combination, to indicate direction and distance to the nearest evacuation exit; the shape providing direction information and the surface contacts providing distance information. The devices also being capable of luminescence to aid in visual as well as tactile reference.

Abstract: A ground fault circuit breaker including ground fault interruption means and overload interruption means that are independently responsive to open a common set of breaker contacts upon respective ground fault and overload conditions is provided with a trip indicator visible external to the breaker that operates on actuation of the ground fault interruption means but not upon operation of the overload interruption means, the trip indicator being a mechanical device that is actuated upon the movement of the solenoid plunger that operates upon occurrence of a ground fault condition.

Abstract: A circuit breaker and alarm device for a circuit having a series connected interruptible current device whereupon a circuit breaker tripping means, attached to said circuit breaker, is adapted to obtain an output voltage of one polarity upon the tripping of the circuit breaker. A circuit breaker resetting device, attached to said circuit breaker, is adapted to obtain an output voltage of reverse polarity upon the resetting of the circuit breaker. A voltage-detecting circuit for sensing the voltage produced by the tripping or resetting of the circuit breaker. A current detecting circuit which produces an output upon detecting an output produced by the voltage-detecting circuit. An alarm circuit which is connected to the current-detecting circuit is thereby caused to essentially instantaneously upon the tripping of the circuit breaker, to energize and remain energized until the resetting of the circuit breaker.

Abstract: An electrical switching device for use on machinery to prevent machine operation unless safety guards or the like are correctly positioned comprises two separate parts one part including at least two Hall effect devices which respond to magnetic poles of opposite polarity and electronic switching means which is actuated only when all the Hall effect devices are triggered simultaneously, and the other part including a corresponding number of magnets positioned to actuate the respective Hall effect devices when the two switch parts are placed in close proximity and predetermined orientation. The switch is substantially tamper proof and a control circuit can detect any unauthorized attempt to override the switch.

Abstract: A solid-state power controller in combination with a solid-state indication circuit is reminded for exhibiting OFF status using a depletion mode field effect transistor that permits an active signal to appear at its source and drain terminals when its gate, coupled to the power controller, is not energized. Such OFF indication circuitry is also combined with solid state ON indication circuitry using a device such as a bipolar transistor to exhibit an output when its base, coupled to the power controller, is supplied a signal.

Abstract: A ground fault circuit breaker including ground fault interruption means and overload interruption means that are independently responsive to open a common set of breaker contacts upon respective ground fault and overload conditions with a trip indicator visible external to the breaker that operates on actuation of the ground fault interruption means but not upon operation of the overload interruption means with means for electrically actuating the trip indicator upon occurrence of a ground fault condition that actuates the ground fault interruption means.

Abstract: An annunciator for a solenoid includes a conductive probe which projects into the pathway of the solenoid core piece. Upon actuation of the core piece, the probe is engaged by the core piece to partially complete an electrical circuit to an external signalling device. The probe includes a lost motion contact to insure proper making and breaking of a circuit upon further movement of the core piece into engagement with the field piece.

Abstract: A simple but effective means for employing alternating polarity current in a discrete inputs can system is disclosed. The system permits scanning of a field contact for open mode, closed mode and for the presence or absence of spurious ground contacts.

Abstract: This switch monitoring circuitry is particularly applicable to switching circuitry for operating a bipolar load device, frequently an inductor, on a source of direct current with four switches arranged to alternate the polarity of potential across the load device in a predetermined periodicity. Such circuitry often is arranged with diode devices individually connected across the switches, especially where the load device is an inductor. The monitoring circuitry specifically described comprises basic logical circuitry having coincidence gating circuits for activating status indicating circuitry; or for controlling associated circuitry for protecting or for compensating the switching circuitry; or for alarming operating personnel of malfunctioning switches.

Abstract: A monitor for logic circuits detects loss of redundancy within the monitored circuit and designates that portion thereof which is out of service. Loss of redundancy is detected by sensing the passage of normal load current, or a portion thereof, through shunt current paths; the occurrence of such current flow coupled with the direction of flow uniquely determining the portion of the logic circuit which is out of service. In a preferred form of the invention, a low ohmic valued resistor is connected in each shunt current path. Upon loss of redundancy, a voltage signal generated across at least one such resistor, is applied to one or more parallel connected amplifiers responsive to the signal to activate corresponding switching circuits and audio/visual indicators.

Abstract: A circuit interrupter characterized by a multipole circuit breaker having line and load terminals and conductor means extending between the terminals for each pair of pole terminals, separate pairs of contacts serially connected in the conductor means, receiver means for sensing a control signal from an external source and sending a corresponding power signal to an operator means to effect opening of one of the pair of contacts.

Abstract: Command words with address signals are transmitted periodically from a control room to field solenoid valves which are each provided with a single actuation circuit. The solenoid valves that are to be actuated in the field each correspond to the address of the transmitted command words which energize the coil of the corresponding solenoid valve. The actuation circuit inserts an address signal for that particular circuit with regard to current information flowing in the energized coil and sends it back to the control room as an acknowledge word. The control room previously predicts acknowledge words which will be sent back by the actuation circuits when the actuation circuits properly respond to the transmitted command words and the control room registers the predicted acknowledge words as reference words. The acknowledge word sent back by the actuation circuit is compared with the reference word and if an inconsistency exists a fault in the actuation circuit is indicated.

Abstract: A triggered before disarmed alarm system uses CMOS circuitry having a hex-inverter integrated circuit with the output logical inverter coupled to the output transistor by a timing circuit that may be selected through control of the presence and absence of a D.C. operating potential to selectively provide pulsating or continuous potential, respectively, to the output transistor that renders the output transistor intermittently and continuously conductive, respectively, in the presence of an alarm signal. Intercoupling circuitry includes resistance capacitance networks with the capacitance shunted by Zener diodes having a voltage rating corresponding substantially to the voltage rating of the capacitance shunted.

Abstract: A current sensing circuit arrangement for controlling the response of a circuit electrically isolated from the circuit in which sensed current is flowing. The input portion of the circuit arrangement provides paths for D.C. input current, one through a current sensing element and another through a light emitting diode circuit. The current-to-voltage characteristic of the current sensing element is such that changes in voltage across the element are substantially less than proportional to changes in current through the element. The light emitting diode circuit is connected in parallel with the current sensing element and produces light energy dependent on the voltage across the element. Light energy so produced is received by an electrically isolated light sensitive semiconductor device which device is for controlling the response of an output control circuit.

Abstract: A level shift circuit for indicating the open or closed condition of an access door of a copier senses the powered condition of operating portions of the copier to which the supply of power is interrupted when the access door is open and provides a corresponding logic signal to a sequence control circuit of the copier. In the disclosed embodiment, a series-connected resistor and zener diode are connected to the copier operating portions to provide an output signal through an inverting buffer to the sequence control circuit.

Abstract: A power transformer having a magnetic core winding assembly disposed within a casing, which contains multiple sensing means to sense abnormalities in fault conditions of the transformer, and an annunciator, having electro-mechanical relay circuits responsive to the sensing means for energizing an alarm circuit. The electromechanical relay circuits are arranged to provide two or more alarm point indication circuits, a pulse circuit and a bistable switching circuit adapted to energize external protective apparatus. The pulse circuit translates one or more sensing means signals of undetermined duration to a single "pulse" signal of predetermined duration. This pulse signal is used to control a switching circuit with a contact connected to operate external protective devices such as an audible alarm. The pulse circuit provides for isolation of the indication circuits from the switching circuit such that each may be reset independently of one another.