Abstract: A fireguard circuit for a power cable, which comprises a power line, a neutral line and a metal sheath surrounding the power line and the neutral line, includes a switch located in one of the lines. A solenoid sets the switch in either an open position or a closed position. A first silicon controlled rectifier (SCR) causes the solenoid to open the switch upon detecting the presence of an arcing condition between the power line and the metal sheath. A second silicon controlled rectifier (SCR) causes the solenoid to open the switch upon detecting the presence of an arcing condition between the neutral line and the metal sheath. The second SCR is connected in parallel with the first SCR, the anode of the first SCR being connected to the cathode of the second SCR and the cathode of the first SCR being connected to the anode of the second SCR.

Abstract: The present disclosure relates to resettable circuit interrupting devices and apparatus capable of being tested and reset from remote locations, and in particular to portable circuit interrupting devices and apparatus capable of being tested and reset from remote locations.

Abstract: A method in connection with a frequency converter, which frequency converter comprises output phases and switches of the output phases, the output phases being switched to feed a load, and the main circuit of the frequency converter being provided with common-mode inductance. The method comprises a step where, in case of earth fault, switches of the output phase having an earth fault are modulated in such a way that the average potential of this phase corresponds to the ground potential.

Abstract: The present invention is directed to a ground fault circuit interrupt (GFCI) device. The GFCI device includes a GFCI device housing. A GFCI circuit is enclosed within GFCI device housing. The GFCI circuit is configured to detect a ground fault condition. A second detection circuit is coupled to the GFCI circuit and disposed within the GFCI device housing. The second detection circuit includes a switch element configured to be in an open position during at least one post-manufacture test procedure and configured to be in a closed position during usage. A protection switch is disposed on the exterior of the GFCI device housing and operatively coupled to the switch element. The protection switch is configured to allow a user to throw the switch element into the closed position without accessing the interior of the GFCI device housing.

Abstract: A generator system includes a generator control for providing electrical power to a main generator. The main generator is mechanically coupled to an electrical power source that provides electrical power to the generator control during operation of the main generator. An arc fault device in electrical communication with the electrical power source electrically isolates the power source from the generator control when an arc fault within the generator control is detected.

Abstract: A method and system for determining whether arcing is present in an electrical circuit includes sensing a change in an alternating current in the circuit and developing a corresponding input signal, analyzing the input signal to determine the presence of broadband noise in a predetermined range of frequencies, and producing a corresponding output signal, and processing the input signal and the output signal in a predetermined fashion to determine whether an arcing fault is present in the circuit. The processing includes determining a type of load connected to the electrical circuit, based at least in part upon the input signal and the output signal, and monitoring high frequency noise in a 20 KHz band for each ? cycle of the alternating current.

Abstract: A method of determining whether arcing is present in an electrical circuit includes sensing a change in current in the circuit and developing a corresponding input signal, analyzing the input signal to determine the presence of broadband noise in a predetermined range of frequencies, and producing a corresponding output signal, and processing the input signal and the output signal in a predetermined fashion to determine whether an arcing fault is present in the circuit. The processing includes determining a type of load connected to the electrical circuit, based at least in part upon the input signal and the output signal.

Abstract: The present invention is directed to a ground fault circuit interrupt (GFCI) device. The GFCI device includes a GFCI device housing. A GFCI circuit is enclosed within GFCI device housing. The GFCI circuit is configured to detect a ground fault condition. A second detection circuit is coupled to the GFCI circuit and disposed within the GFCI device housing. The second detection circuit includes a switch element configured to be in an open position during at least one post-manufacture test procedure and configured to be in a closed position during usage. A protection switch is disposed on the exterior of the GFCI device housing and operatively coupled to the switch element. The protection switch is configured to allow a user to throw the switch element into the closed position without accessing the interior of the GFCI device housing.

Abstract: A system and method for an arc fault detection system for aircraft wiring system is disclosed. Upon detection of arc fault events, the system transmits a signal that may be sent to an existing circuitry of the aircraft electrical system, which disconnects the power to the circuits, thereby extinguishing the arc. The system can be either utilized as a stand-alone system or incorporated into existing products or systems. When an arc event occurs on a power cable, a broadband noise event is similarly induced upon the affected cable. The system first uses a pick-up coil (15) to sense and pick up this broadband signal from the power cable (5) of the wiring system, and then amplifies (17) the signal. The amplified signal is applied to a high-pass filter (20) to only pass frequency components above a predetermined frequency.

Abstract: An arc-fault detecting circuit-breaker system is operable with a protected electrical circuit that operates with direct current or alternating current. A normally closed line circuit breaker has an electrical input and an electrical output, and an electrical line connects the electrical output to the protected-element input. The system includes a detector of the rate of change with time of a current flow in the electrical line. An activating element alternating current voltage source has an alternating current output. A circuit-breaker activating element is operable responsive to the detector. The circuit-breaker activating element is electrically connected between the electrical line and the alternating current output.

Abstract: The continuity of the coil of the actuating solenoid of an electric power switch is detected through utilization of a signaling device, such as a light emitting diode (LED) that monitors energization of a dc power supply fed from the source side of the coil. A circuit energized from the other side of the coil generates a dc voltage V2 that is applied to the gate electrode of an electronic switch shunting the LED. The voltage V2 is greater than the dc supply voltage to bias the electronic switch off so that the LED is illuminated when there is continuity through the coil. If the coil fails, V2 will be zero and the electronic switch is turned on to short circuit the LED to signal the failure of the coil.

Abstract: Resettable circuit interrupting devices using a center latch are provided. The circuit interrupting devices include those with a reset lockout, reverse wiring protection, and/or an independent trip portion.

Abstract: A method of protecting safe side wiring of a protective energy barrier against transferring fault energy into a potentially explosive environment comprises the steps of: enclosing the safe side wiring with at least one layer of shielding completely along the length thereof, the at least one layer of shielding capable of conducting the fault energy; connecting the safe side wiring at one end to circuitry of the protective energy barrier through a first connector having a housing which completely surrounds the safe side wiring prior to entering the protective energy barrier and is capable of conducting the fault energy; connecting the at least one layer of shielding of the safe side wiring to the housing of the first connector to conduct fault energy therebetween; connecting the safe side wiring at another end to circuitry within the potentially explosive environment through a second connector having a housing which completely surrounds the safe side wiring prior to entering the potentially explosive environmen

Abstract: Fault abatement circuit breaker for providing protection of critical loads. The circuit breaker provides both arc fault protection and fault lockout protection in one integrated circuit breaker. The fault lockout protection reduces the risk of short circuit damage by predicting and preventing the event. The arc fault protection trips the circuit breaker when arcing is sensed. The integrated circuit thus provides for a minimum of short circuit damage, thereby maximizing process and/or equipment up time.

Abstract: A system for electrically isolating and indicating electrical isolation of a machine including a plurality of relays which cooperate to, when electrical isolation is selected, ground voltage input lines to the machine thereby ensuring that no power is provided to the machine during operator access thereto.

Abstract: An AC power line protection device which includes a protection circuit which guards against miswiring also has an indicator lamp which lights when the device is in the tripped condition and turns off when the device is reset. If the device is miswired after having been wired properly, the indicator lamp does not light when the device is tripped, and so provides a supplemental indication of miswiring. The protection circuit is powered from the hot line bus bar. The indicator lamp is also powered via the hot line bus bar of the interrupting contacts to meet safety standards.

Abstract: A method of protecting safe side wiring of a protective energy barrier against transferring fault energy into a potentially explosive environment comprises the steps of: enclosing the safe side wiring with at least one layer of shielding completely along the length thereof, the at least one layer of shielding capable of conducting the fault energy; connecting the safe side wiring at one end to circuitry of the protective energy barrier through a first connector having a housing which completely surrounds the safe side wiring prior to entering the protective energy barrier and is capable of conducting the fault energy; connecting the at least one layer of shielding of the safe side wiring to the housing of the first connector to conduct fault energy therebetween; connecting the safe side wiring at another end to circuitry within the potentially explosive environment through a second connector having a housing which completely surrounds the safe side wiring prior to entering the potentially explosive environmen

Abstract: A transformer assembly and method for powering a load with a secondary fault protected isolated secondary. The fault fault path is isolated from ground allowing voltage detection of faults and the return terminal is isolated from the midpoint for multiple load connection schemes using the midpoint as a ground connection. A power control system is connected between the primary winding and the input terminal with a ground fault detection circuit connected between the fault path and the ground terminal, where the ground fault detection circuit is operable to detect a fault and activate the power control system to disconnect the source of power from the primary winding in response to detecting the fault. Also disclosed is a high frequency filter adapted to reduce the effects of high frequency transients and a capacitive reactance connected between the input terminal means and the ground terminal. The capacitive reactance is adapted to provide a ground fault path for fault signals.

Abstract: An annunciation system which will detect the majority of failed breakers and indicate to the consumer when a breaker needs to be replaced, but does not put the consumer in an emergency situation where critical loads have lost power. The annunication system provides a visible and audible indication of the failure of a breaker to trip either as a result of fault current conditions or a test of a ground fault or arc fault circuit.

Abstract: The invention relates to a retrofittable earthing device in which a first contact (1) which is to be arranged on the switching device (3) and a second contact (13) which is to be arranged on the module frame (10) by means of a contact carrier (20) are adjacently spring-mounted, during the movement of the switching device (3) from its point of separation into its operating position. In order to relieve the contact carrier (20), in one such device, of electrodynamic effects and thus to make the same easy to assemble, said contact carrier (20) comprises a first partial region (23) for connecting an earthing means, and a second partial region (24) which can be connected to the second contact, in addition to a contact strip (25) connecting the two partial regions.

Abstract: The attenuation of the stray current impulse limits the capacitive leakage. The value of the inductance, coupled to the parasitic capacitance of the charge, creates a reactive filter effect. Since the effect is reactive, the impulse energy is not absorbed. The energy is therefore redistributed in time, but since the intensity of the tension is greatly diminished, the coupling through the capacitances is diminished. The apparatus comprises a core which includes 1, 2, 3 or 4 coils. The apparatus is typically a high quality reactance which includes a low reactive value in opposition of the line current (residual mode) and a high reactive value for the circulation of the parallel current (common mode).

Abstract: An AC power line protection device which includes miswiring protection has an indicator lamp which lights when the device is in the tripped condition and turns off when the device is reset. If the device is miswired after having been wired properly, the indicator lamp does not light when the device is tripped, and so provides a supplemental indication of miswiring. The indicator lamp is powered via the hot line bus bar of the interrupting contacts to meet safety standards.

Abstract: An AC power line protection device which includes miswiring protection has an indicator lamp which lights when the device is in the tripped condition and turns off when the device is reset. If the device is miswired after having been wired properly, the indicator lamp does not light when the device is tripped, and so provides a supplemental indication of miswiring. The indicator lamp is powered via the hot line bus bar of the interrupting contacts to meet safety standards.

Abstract: A signaling system employing indicator lamp means and an audible alarm is employed to remind a user to periodically test his GFCIs and to provide information regarding the status of the GFCI. The power lines that supply the GFCI with power are also coupled to the circuits on the PCB to disconnect power to those circuits of the GFCI that trips due to faults or tests.

Abstract: A fault protective device (48) for limiting the maximum current and voltage applicable to electronic components and wiring (26, 30) located in the fuel tank (10) of an aircraft. Particularly, a fuel gauging system circuit (18) extends from a generator (20) located outside the tank to at least one probe (14) located in the tank and from the probe to instrumentation (24) outside the tank. The device is electrically coupled to the circuit at the tank wall (28) and includes a voltage clamp (50) and series inductor-capacitor resonant circuit (46), so that the resonant circuit provides a low series impedance when applied with a signal at the operating frequency of the input signal applied by the generator but provides a high series impedance when experiencing a signal of a different frequency indicative of a system fault.

Abstract: A combination circuit breaker/motor starter includes a circuit breaker trip unit having a microprocessor and at least one removably connectable contactor or other functional module. The functional module is encoded with an identifier, such that the microprocessor can determine the type of functional module and appropriate configuration parameters, such as trip times, for the particular application of the functional module. Power is supplied continuously to the trip unit during motor overload or short circuit conditions.

Abstract: A multi-grounded neutral electrical isolation system for a personal-communication-system cell site consists of two standard distribution transformers separated by a distance greater than the zone of influence corresponding to the maximum expected ground potential rise at the PCS cell site. The primary winding of the first transformer is connected to the utility's low-voltage distribution system and is grounded through the network's ground. The secondary winding is connected to the primary winding of the second transformer through a high-voltage non-shielded insulated conductor and the frames of the two transformers are kept electrically isolated. The secondary winding of the second transformer energizes the PCS cell site and shares its ground connection, which is also common to the adjacent high-voltage transmission tower. All neutrals are grounded through their respective grounding systems.

Abstract: Apparatus and process are provided for suppressing interference caused by ground loop currents associated with two A.C. power-line operated electrical/electronic equipment units, such as an audio source and an amplifier, where typically the ground loop includes a shielded signal cable interconnecting the two equipment units. A signal representing current sensed from a selected region of the ground loop is amplified and injected into a second region of the ground loop as a counteractive current having polarity opposite that of the original ground loop current, thus tending to nullify the interference. The amplification may be made adjustable for optimal suppression. Ground loop current may be sensed by a sensing transformer coupled to the loop or by a pair of sense lines, connected to selected nodes in the ground loop such as respective ground terminals of the two equipment units, and providing the sensed signal to differential amplifier inputs.

Abstract: Stray voltage reduction system for reducing electrical shocks to livestock in a farm and similar building wherein the system senses a voltage between first and second components, such as metal stall stanchion and metal water trough, of a livestock enclosure or holding area and electrically shorts the first and second components for a preset time period when a stray voltage beyond a preset trigger voltage potential difference is detected between the first and second components. The device includes a voltage sensing circuit for sensing voltage between the first and second components, a comparator, and electrical shorting circuit that can include a relay actuated switch responsive to the output of the comparator when a sensed potential difference between the first and second components equals or exceeds a preset trigger value to electrically short (switch closed by relay) the components for a time to reduce the voltage below the trigger value.

Abstract: The present invention relates to suppressing transient impulses in a power distribution system and more particularly to a device and method for suppressing transient impulses at frequencies which exceed the power frequencies while maintaining an acceptable "safety" impedance level at the power frequencies.

Abstract: A ground fault current limiter, in which reactors are connected in series to a neutral point for compensating for capacitances to ground of a power switches capable of turning ON/OFF at a high speed are connected in parallel with respective reactors, occurrence of a ground fault is detected from a phase difference between a zero-phase sequence current and a zero-phase sequence voltage at time of sampling, an optimal compensation quantity of capacitances to ground is computed based on the zero-phase sequence current and the zero-phase sequence voltage at time of occurrence of a ground fault, and ON/OFF of the switches are controlled thereby to alter the reactor quantity so as to correspond to the compensation quantity.

Abstract: A transformerless conditioner of a power distribution system consists of an electronically enhanced filter (EEF) for suppression of transient impulses on the power line and neutral line, and a transformerless ground conditioner for suppression of transient impulses on the ground line. The filter includes a normal mode filter having an inductor located on the power line and an inductor located on the neutral line between source and load of the power distribution system, and a pair of capacitors arranged in series and connected between the power and neutral lines, whereby a midpoint tap is formed between the pair of capacitors. The EEF also includes a unique common mode filter which is formed by the series connection of either inductor of the power line or the neutral line, or both, to its corresponding capacitor and then to the midpoint, from which an electronic impulse detector is connected to ground.

Abstract: In a ground fault circuit interrupter in which it was found that wide band noise induced by load transients is rectified by an op-amp in the detector circuit, false trips due to the wide band noise are eliminated by only comparing the output of the amplifier with a threshold of opposite polarity to that of the rectified noise signal and by eliminating capacitive coupling between the current sensor and the op amp. This requires an op amp with a low offset, on the order of about five percent or less.

Abstract: A coupler providing coupling for power line communications between the power lines carrying different phases of the power. The coupler engages an ordinary wall outlet such as a 220 volt outlet and includes a receptacle for a 220 volt plug. Internally, the adaptor has high frequency coupling between the power lines. The coupling presents a high impedence to the power signal.

Abstract: Stray voltage reduction apparatus for installation in an electrical power system to complete a path of electrical continuity between a primary neutral of a power distribution transformer and a grounding conductor at a service entrance, the primary neutral being also attached to a ground connection but nevertheless having a stray voltage relative to true earth which would appear on the grounding conductor at the service entrance if the primary neutral were directly connected to the grounding conductor at the service entrance. The stray voltage reduction apparatus includes a coil having turns wound around a core establishing a magnetic circuit for the coil. The core is made of a material having an initial permeability in excess of about 50,000 and being substantially saturated when the flux density is no more than about 10,000 gauss. The coil is wound around the core to have an impedance at 60 Hz.

Abstract: Re-strike in the circuit breaker of a capacitive load applied across an AC voltage power supply is reduced or avoided by connecting across the capacitor bank a tuned discharge circuit. The tuned discharge circuit includes a transformer with a primary connected in parallel with the capacitor bank and a secondary which can be shorted through a switch. The leakage reactance of the transformer is equated to the capacitive reactance of the capacitor bank so that the tuned circuit discharges the capacitor voltage in phase with the supply voltage. The discharge takes place through a number of cycles thus gradually increasing the voltage across the breaker gap. The switch in the secondary preferably comprises an anti-parallel pair of thyristors fired by a circuit responsive to current zero in the capacitive circuit detected over a delay period to avoid firing at normal zero crossing current.

Abstract: A device for continuous supervision of the attenuation (d), dissymmetry (k) and mismatch (v) system parameters in impedance earthed power systems. The parameters are calculated from the circle diagram uEN=f(v), i.e., the relative neutral point voltage as a function of the mismatch. The circle diagram is in turn defined by two measuring points for uEN which are derived by connection or disconnection of a reactance complement between system neutral and earth. The invention improves known devices for control of the condition of impedance-earthed power systems. Then the continuous supervision of the mentioned power parameters enables a better detecting of high-resistive earth connections.The invention can be implemented in any computer system capable of providing the necessary measurement, control and calculating functions.

Abstract: A grounded capacitor in a switched-mode power supply provides AC line EMI filtering, reduced current leakage, and high voltage isolation. The capacitor is coupled between an AC rectifier circuit and the controlled switching devices of the power supply to provide the capacitor with a lower conduction angle, i.e., the grounded capacitor will only conduct a leakage current during periods when diodes within the rectifier circuit are conducting. The low impedance ground return path for the switching device output signal permits the use of a filter capacitor having a large capacitance which affords improved power supply line isolation and enhanced safety.

Abstract: A switching system for interrupting an electrical circuit is described. This switch includes a number of preferred and other embodiments which have this as their goal, but which represents a number of distinctive and novel approaches to solving switching problems in the prior art. By way of example only, these approaches include provision of mounting strap which supports ground terminals while also serving as a magnetic circuitry conduit; a "banger" type arrangement which enables alternate making and breaking of a circuit; and a space-saving method for supporting the arrangement within a device or system able to be installed within a conventional receptacle box.

Abstract: In a power supply system having a grounded neutral and supplying service equipment through a distribution transformer, a ground voltage suppression device comprises a saturating inductor or like non-linear impedance device connected between the secondary neutral conductor and a normal ground conductor so as to define therewith a neutral-to-ground current path which presents a high impedance to current flow for applied voltages up to a predetermined level.

Abstract: Shield of telecommunications cable is grounded through negative impedance converter to reduce induced voltage in conductors in the cable caused by electromagnetic field of nearby powerline.

Abstract: A secondary arc extinction device in an electric power system, including a bus bar; an electric power line connected to the bus bar; protective relaying means connected to the bus bar; first reactance means having two terminals, one terminal of which is connected to the electric power line; a transformer having a primary winding and a secondary winding connected between the other terminal of the first reactance means and ground; second reactance means connected to the secondary winding of the transformer; and means for controlling the second reactance means in response to the protective relaying means.

Abstract: A control system for eddy current coupling drive for armoured face conveyors wherein the systems controls a number of eddy current drives via a pair of power supply lines and a single pilot line. A main contactor controlled by a relay is held closed by contact of a pilot relay which is energized only if relay contacts in individual control units for each drive remain closed. These last mentioned contacts open if certain operating conditions are not met.

Abstract: A secondary arc extinction device in an electric power system including a bus bar; an electric power line connected to the bus bar; protective relaying means connected to the bus bar; a transformer having a primary winding and a secondary winding, one terminal of the primary winding being connected to the electric power line; first reactance means connected between the other terminal of the primary winding of the transformer and ground; second reactance means connected to the secondary winding of the transformer; and means for controlling the reactance of the second reactance means in response to the protective relaying means.

Abstract: A current limiting device for use with a circuit breaker in an electric power system utilizes mutual inductance variation between movable windings to limit current to safe levels. In the device, first and second coil windings are electrically connected for current flow therethrough and magnetically linked for mutual inductive coupling. The effective inductance of the connected coil windings is functionally related to the relative physical positioning of the coil windings. The coil windings are movable relative to one another, so as to provide for variation in the effective inductance of the two coils. Structure is provided for disposing the coils in an initial relative positioning, the structure being yieldable to a force produced between the coils due to a predetermined magnitude of current flow through the coils. The force produced between the coils acts to change the relative positioning of the coils, increasing the effective inductance, and thereby limiting the current therethrough.

Abstract: An isolating connector is disclosed for isolating the center conductor of a shielded cable from DC and low frequency AC potentials. The connector includes a generally tubular shell which is connected to the cable's shield and within which a connector pin is located for coupling to a female plug. A capacitance inside the shell is connected in series with the pin and the cable's inner conductor. Also inside the shell are two bleeder resistances, one connected in parallel with the capacitance and another connected in series between the shell and the connector pin. With this arrangement, any DC or low frequency AC potential appearing on the cable's inner conductor is isolated from the connector pin, and a discharge path is provided for the capacitance in the shell and any capacitance serially coupled with the cable's shield.

Abstract: A solid state load protection system having an inverse time delay circuit. A current sensing function is utilized so as to produce an output current which is proportional to the current in an electrical circuit. Attached to the current sensing function is a load resistor which converts the current produced by the current sensing function to a voltage which is proportional to the current utilized by the load. Attached to the load resistor is an inverse time delay circuit which serves as an overcurrent and timing function. The overcurrent and timing function monitors the level of voltage from the load resistor initiating a time-out sequence when the voltage across the load resistor, which is proportional to the current utilized by the load, exceeds a predetermined level for a predetermined period of time. The overcurrent and timing function utilizes two diode paths for prohibiting the charging or discharging of a capacitor during a normal or overcurrent condition, respectively.

Abstract: A switched four-legged reactor bank which operates in combination with line circuit breakers can be used to extinguish faults on untransposed transmission lines. It comprises three shunt reactors, a neutral reactor and three switches for performing high side reactor switching. The reactor bank also provides transmission line compensation.

Abstract: Electrical loads connected to capacitance elements in high voltage direct current systems are protected from damage by capacitance discharge overcurrents by connecting between the capacitance element and the load, a longitudinal inductor comprising a bifilar winding wound about a magnetic core, which forms an incomplete magnetic circuit. A diode is connected across a portion of the bifilar winding which conducts a unidirectional current only. Energy discharged from the capacitance element is stored in the inductor and then dissipated in an L-R circuit including the diode and the coil winding. Multiple high voltage circuits having capacitance elements may be connected to loads through bifilar windings all wound about the aforementioned magnetic core.

Abstract: Disclosed is a means for reducing leakage current associated with a path used to couple a high impedance sensor to a detector as, for example, in coupling a smoke-sensitive ionization chamber to an integrated circuit smoke detector chip. A unity gain amplifier is provided which receives a detection voltage signal from the sensor and generates an output guard voltage which tracks the detection voltage signal. The output guard voltage is used to bias the voltage of the areas surrounding the path used to conduct the detection voltage signal. The effect of undesirable leakage paths that may exist between the detection voltage signal conduction path and surrounding areas is reduced by minimizing the voltage across the leakage paths, thus maintaining a high impedance value associated with the detector input.