Abstract: A circuit interrupter includes a trip actuator configured to cooperate with an operating mechanism to trip open separable contacts. The circuit interrupter also includes a ground fault sensor configured to sense a difference between a current through a first electrical conductor and a current through a second electrical conductor and to output an output current based on the sensed difference and a ground fault amplifier circuit configured to convert the output current to an output voltage. The circuit interrupter also includes first and second switches configured to electrically connect the output of the ground fault sensor to the ground fault amplifier circuit and the trip actuator, respectively. The circuit interrupter also includes a processor configured to control operation of the first and second switches and, when the first switch is closed, to control operation of the trip actuator based on the output voltage.

Abstract: The present disclosure provides an industrial GFCI for control panels and/or industrial machines. The industrial GFCI senses when a fault condition has occurred in an associated circuit or load and quickly disconnect the circuit. In some exemplary embodiments, the industrial GFCI includes a bypass switch, which couples a load directly to a power source, bypassing fault detection. In some exemplary embodiments, the industrial GFCI also includes intelligent filtering, which discriminate between true fault events and false signals caused by environmental noise. Further, the industrial GFCI is manufactured as a part of a control panel or a piece of equipment. In certain exemplary embodiments, the industrial GFCI is manufactured as a portable kit capable of coupling to and decoupling from one or more control panels, machines, etc.

Abstract: A fault detecting device having a plurality of supply conductors, including a first current transformer having a primary winding comprising at least two supply conductors and a secondary winding into which a current is induced in response to a fault current in the primary winding. A fault detection circuit connects the secondary winding to an electromechanical actuator having mechanical contacts in the supply conductors, the fault detection circuit generating an output signal to the actuator when an induced current is detected in the secondary winding, the output signal causing the actuator to open the mechanical contacts. The device further includes a second current transformer having a primary winding connected to an oscillator and a secondary winding comprising at least one supply conductor, the second current transformer arranged to induce an oscillating current into the at least one supply conductor in the event of a fault condition.

Abstract: Electrical load controls are provided which include an electrical switch assembly and a fault protection device within a common housing. The switch assembly includes an actuator, and is responsive to actuation of the actuator to switch ON or OFF electricity to the load. The protection device automatically responds to a fault condition by overriding the switch assembly by automatically blocking electrical connection between phase input and output terminals and neutral input and output terminals of the load control. The actuator includes a single external interface element. In one embodiment, actuation of the actuator switches ON or OFF electricity via control of the fault protection device, and in another embodiment, movement of the interface away from the housing exposes within the housing an internal user interface for the fault protection device.

Abstract: Circuit interrupting devices are provided. One circuit interrupting device includes a fault sensor configured to output a sensor signal; a voltage sensor configured to sense a reference voltage; and a controller configured to determine an occurrence of an actual fault based on the sensor signal and the reference voltage. The circuit interrupting device further includes an amplifier configured to receive the sensor signal and the reference voltage and output an amplified signal; an analog-to-digital converter configured to receive the reference voltage and the amplified signal and output respective digital signals corresponding to the reference voltage and the amplified signal; and a line interrupt assembly configured to interrupt current flow through a conductive path when a characteristic of the sensor signal exceeds an actual fault threshold.

Abstract: Disclosed herein are apparatus, methods, and systems for monitoring and detection of conditions indicative of an electrical fault for an electrical circuit or system. In one aspect, a central control can simultaneously monitor a plurality of geographically distributed electrical circuits or systems for conditions that have been predetermined to be indicative of an electrical fault or concern, and provide either some communication (e.g., a warning) or instruction (e.g., to terminate power) back to the monitored circuit/system, the owner/operator/user of the circuit/system, or both. The central control can collect, store, mine, and analyze data from the diverse monitoring of plural systems. A knowledge base can be built up over time and used to establish monitoring of the same, other circuits and systems, develop more accurate monitoring and communication of faults or concerns, and account for factors related to normal operation of a circuit or system.

Abstract: An arc fault circuit interrupter is disclosed. This arc fault circuit interrupter can include any one or more of three different sensors such as a high frequency sensor, and any one of lower frequency sensors such as a current sensor or a differential sensor. The arc fault circuit interrupter can be configured as an in line arc fault circuit interrupter installed in a wall box. In addition, the arc fault circuit interrupter can include a processor configured to determine any one of a series arc fault, or a parallel arc fault.

Abstract: A method of setting a ground fault trip response function for a trip unit includes enabling a ground fault protection mode for the trip unit, setting the ground fault trip response function for the trip unit, wherein the ground fault trip response function is a double knee time current function.

Abstract: The present invention is directed to a protective electrical wiring device that includes at least one first stop member disposed proximate at least one first conductor. The at least one first stop member is configured to limit the movement of the at least one first conductor when the circuit interrupting assembly moves between the reset position and the tripped position such that a gap is established between the plurality of circuit interrupting contacts in the tripped state, the gap being substantially greater than or equal to a predetermined distance.

Abstract: For monitoring the isolation of an IT-grid with respect to ground, an inverter connecting a direct current side with an alternating current side of the IT-grid and a photovoltaic device on the direct current side of the IT-grid, at least one isolation resistance of the direct current side with respect to ground is monitored for falling below a resistance threshold value while the inverter is running, and additionally a leakage current via the inverter towards ground is monitored for exceeding a current threshold value.

Abstract: The present invention relates to a ground fault detecting and controlling method for a parallel-structured high voltage system, and more particularly, such a ground fault detecting and controlling method for a parallel-structured high voltage system, in which it can be more precisely determined whether or not the system operation is emergently stopped based on individual insulation resistance values for respective items of the system, and it can be determined whether there is the possibility of temporary operation of the system in the emergency stop situation of the system operation. According to the present invention, a combined insulation resistance ground fault reference value is calculated based on individual insulation resistance values for respective items of the system, and the entire system is controlled by using the calculated combined insulation resistance ground fault reference value such that a high-accuracy ground fault detecting and controlling method can be provided.

Abstract: An inverter includes two input lines for connecting the inverter to an AC power source, a buffer capacitance effective between the input lines, a grounded potential equalization busbar, an isolation monitoring device monitoring the electrical isolation of one of the two input lines with regard to the potential equalization busbar, and an overvoltage eliminating device having at least one overvoltage eliminator for draining overvoltages from the input lines to the potential equalization busbar. The at least one overvoltage eliminator is connected between that input line, whose electric isolation with regard to the potential equalization busbar is monitored, and the potential equalization busbar, without any fuse being connected in series with the at least one overvoltage eliminator. Any overvoltage eliminator of the overvoltage eliminating device, which is connected between the other of the two input lines and the potential equalization busbar, if present, is connected in series with a fuse.

Abstract: A GFCI device with circuit condition detection function includes a leakage current detection circuit, a disconnect mechanism, a reset mechanism, a circuit condition detection and control circuit, and a selection switch. The disconnect mechanism includes a first SCR controlled by the leakage current detection circuit. The circuit condition detection and control circuit includes a first control circuit and a second control circuit. When the first control circuit is connected to an anode of the first SCR by the selection switch, it provides an intermittent simulated leakage current to the leakage current detection circuit, and the leakage current detection circuit provides a trigger signal for a control gate of the first SCR, so that the first control circuit generates an intermittent simulated leakage current. When the leakage current detection circuit is not operational to generate the trigger signal, the first control circuit generates a control signal to disable the GFCI device.

Abstract: A leakage current masking device for use with a circuit includes at least one inductive load device coupled to the circuit and configured to supply an inductive load to the circuit, and a processor communicatively coupled to the inductive load device. The processor is configured to receive a signal representative of a current through the circuit, calculate a capacitive leakage current component of the current, and cause the inductive load device to adjust the inductive load supplied to the circuit to reduce the capacitive leakage current component.

Abstract: The present invention provides a circuit interrupting device which comprises a leakage current detection and protection circuit containing a simulated leakage current generation circuit which is capable of automatically generating a simulated leakage current when the circuit interrupting device is properly wired and in a tripped state to automatically test the functions of the key components of the circuit interrupting device. The simulated leakage current generation circuit comprises a normally closed switch and a normally open switch. The leakage current detection and protection circuit further comprises a normal status indicator light and a power output indicator light to indicate whether the circuit interrupting device is working properly and/or reverse wired. The circuit interrupting device further comprises a reset switch, a pair of discharged metal pieces, and four pairs of circuit interrupting contacts.

Abstract: The present invention relates to current measurement apparatus. The current measurement apparatus comprises first and second measurement devices with each of the first and second measurement devices being operative to measure current in a respective one of a live conductor and a neutral conductor substantially simultaneously. The current measurement apparatus is operative to make plural different determinations in dependence on the substantially simultaneous current measurements.

Abstract: This invention relates to a residual current device which is able to safely and reliably operate when a line voltage is present (voltage dependent mode) and when the line voltage is not present or falls below a predetermined threshold level (voltage independent mode). The present invention is implemented as a residual current device having a trip mechanism for isolating an electric supply to an electrical installation upon detection of a predetermined current imbalance between the line and neutral conductors of said electric supply. The present invention comprises a current transformer having a secondary winding responsive to any current imbalance on said electrical installation, and a circuit protection winding being connectable to a processing means.

Abstract: Disclosed herein is an abnormal current detection circuit for circuit breaker, comprising a full-wave amplifier, a positive wave-period comparator for comparing a positive wave-period amplification voltage signal with a positive wave-period reference voltage signal to output a pulse signal, a negative wave-period comparator for comparing a negative wave-period amplification voltage signal with a negative wave-period reference voltage signal to output a pulse signal, a combining circuit for combining pulse signals outputted from the positive wave-period comparator and the negative wave-period comparator to output a full-wave combining signal, a reference voltage generator for generating a reference voltage signal, and a comparative driving circuit section for comparing the combining signal with the reference voltage signal to output a signal for controlling a circuit breaker to be driven to a circuit breaking position when the combining signal is greater or equal to the reference voltage signal.

Abstract: A fusing device of an image forming apparatus including a fusing element in which a heat generation layer is formed and a pressurization element that forms a fusing nip by pressurizing and contacting the fusing element, the fusing device including: a power supplier for supplying a power supply voltage to the heat generation layer to heat the heat generation layer; a current signal detector for detecting a current signal corresponding to a difference between an input current of the heat generation layer and an output current of the heat generation layer; a determination unit for determining whether current leaks out of the heat generation layer by analyzing the current signal detected by the current signal detector; and a power breaker for preventing the power supply voltage, supplied from the power supplier, from being supplied to the heat generation unit, if the determination unit determines that current leaks out of the heat generation layer.

Abstract: An integrated DC link inductor and current sensor winding having a core that includes at least two primary legs and at least one secondary leg, two direct current (DC) link windings each wound around one of the two primary legs, and a common mode current sensor winding wound around the secondary leg. Resistors coupled to the common mode current sensor winding may damp the common mode current oscillations.

Abstract: An apparatus and method for providing ground fault protection to a lifting device utilizing an electromagnet and powered by a generator. The apparatus and method rectifies an AC voltage emanating from the generator source and monitors unsafe operating conditions of the generator's circuit wherein operation of the lifting device is ceased when predetermined electrical operating parameters are exceeded.

Abstract: Methods and apparatus to minimize saturation in a ground fault detection device are disclosed. An example method includes connecting a capacitor simulator to a node of the ground fault detector device to prevent saturation, and monitoring power-line conductors for ground fault conditions with the ground fault detector device. An example apparatus to simulate a saturation capacitance in a ground fault device includes a sense coil induced by power-line conductors, and at least one of an amplifier or a current detector including an input connected to the sense coil and an output connected to a ground fault detector. The example apparatus also includes a saturation capacitor simulator connected to a node of at least one of the amplifier or the current detector to prevent saturation.

Abstract: The invention relates to an arrangement (10) for ground fault monitoring of an AC circuit between, on one hand, a neutral conductor (N?) of the AC circuit and, on the other hand, a protective ground wire (PE) or a ground wire with a series connection of ohmic resistors (R1, R2, R3), which has a first terminal (101) for the neutral conductor (N?) and a second terminal (102) for the protective ground wire (PE) or ground wire, wherein the arrangement includes at least one means for detecting a break of one of the resistors (R1, R2, R3) of the series connection.

Abstract: One embodiment relates to a fault circuit interrupter comprising at least one grounded neutral sensor and at least one test circuit configured to test the grounded neutral sensor. A further embodiment can also include at least one fault circuit which is configured to detect a current sent from the grounded neutral sensor. The device can also include a line side phase line, a line side neutral line, and a test line coupled to the line side neutral line and extending from a first region on the line side neutral line to a second region on the line side neutral line, with the grounded neutral sensor being positioned between the first region and the second region on the line side neutral line. This test circuit can comprise a switch, such as a manually operatable switch or it can comprise any one of solid state circuitry, a transistor, and/or a silicon controlled rectifier. The device can also include a differential sensor and at least one second test circuit configured to directly test differential sensor.

Abstract: An automotive vehicle includes a charge port integrated with the vehicle. The charge port includes electrical contacts configured to receive electrical power from an electric grid, and a fault interrupt circuit electrically connected with the electrical contacts.

Abstract: A ground protection circuit (36) includes: a sensing resistor (R3), disposed on a path which a charging current (IB) of a bootstrap circuit (D1, C1) flows through; a comparator (361), for comparing a voltage (?V) between two ends of the sensing resistor (R3) and a specific threshold voltage (Vth) to generate a ground protection signal (S1); and a logic gate (362), for enabling the ground protection signal (S1) to be invalid in a normal charging operation of the bootstrap circuit.

Abstract: The present invention provides a novel circuit interrupting device, preferably a ground fault circuit interrupter, which contains a reset button that is capable of interacting with a test button to perform an end-of-life-component test on the circuit interrupting device. The circuit interrupting device also contains a reset switch coupled to the reset button which is capable of disallowing reset if the device is miswired and/or fails the end-of-life-component test. Only when the circuit interrupting device is properly wired, in a tripped state, and all of the key components in the circuit interrupting device are working properly, the depression of the reset button allows the device to be reset.

Abstract: A circuit breaker apparatus may be used to interrupt overcurrent and ground fault in a circuit. The circuit breaker apparatus may include an overcurrent coil for tripping the circuit breaker apparatus, a voltage coil also for tripping the circuit breaker apparatus located proximate to the overcurrent coil, ground fault electronics connected to the voltage coil and structured to detect a ground fault in the circuit when the ground fault exceeds a threshold level, and a solid state switch. The ground fault electronics can be structured to send a trip signal to close the solid state switch when a ground fault is detected, the solid state switch is configured to force a current through the voltage coil when the solid state switch is closed, the current being of sufficient magnitude to trip the circuit breaker apparatus.

Abstract: A residual current device for an AC electricity supply comprises a housing (10) and a first load conductor (L) inside the housing connected in series between the supply and a load and including a set of contacts (18) by which an electrical connection between the supply and the load may be made or broken. A current transformer is disposed inside the housing and has a toroidal core (TI) the first load conductor passing through the core and forming one primary winding of the current transformer. At least one further load conductor (N) outside the housing passes through the core (T) via an opening (32) in the housing and forms a further primary winding of the current transformer. A secondary winding (W) on the core produces an output in response to a residual current, and a circuit (RCC) inside the housing is responsive to the output on the secondary winding to open the contacts if the residual current is above a predetermined level.

Abstract: A surge protection circuit comprises a surge detection circuit 14 for detecting a surge applied to a semiconductor integrated circuit, and a protection element 15 for absorbing the surge. The protection element is connected between a signal terminal for supplying a signal to the semiconductor integrated circuit and a power source terminal for supplying a power source voltage. When the power source voltage is not larger than a voltage enough to normally operate the semiconductor integrated circuit and the surge detection circuit does not detect the surge, the protection element is set in a current limiting state. When the power source voltage is not larger than a voltage enough to normally operate the semiconductor integrated circuit and the surge detection circuit detects the surge, the protection element is set in a current non-limiting state.

Abstract: A leak detecting and leak protecting circuit comprises a rectification circuit comprising positive and negative power output ends, current limiting resistors, a diode, a silicon control comprising control poles, a switch capable of linking to a resetting button, and a tripping coil comprising a built-in iron core. The rectification circuit outputs DC power. The tripping coil, switch, and silicon control are connected in series and then are connected to the positive and negative power output ends of the DC power output from the rectification circuit. The control poles of the silicon control are capable of connection with a shielding layer of output wires through at least one of the current limiting resistors and a diode. And, when the switch is in a resetting state, the switch is closed, and, when the switch is in a tripped state, the switch is open.

Abstract: There is disclosed a circuit interrupting device with symmetrical inputs comprising a first input configured for connection to a power source or a load circuit and a second input configured for connection to a power source. There are a plurality of electrical conductors extending from the first and second inputs and a third input configured for connection to a load provided by a user. There is also a first set of transformers comprising at least one differential transformer and at least one neutral transformer connected to detect leakage current in a load circuit coupled to the first set of terminals. There is also a second set of transformers comprising at least one additional differential transformer and at least one additional neutral transformer connected to detect leakage current in a load circuit coupled to the second set of terminals.

Abstract: A ground fault circuit interrupter (GFCI) includes a GFCI controller configured to detect for ground faults and to periodically perform a self test. The self test may be performed during a positive half cycle of an AC line voltage coupled to a load by the GFCI. The self test may include testing of a critical component of the GFCI without opening load contacts coupling the AC line voltage to the load. The self test may further include testing of monitoring coils in the GFCI.

Abstract: The present invention is directed to a protective wiring device for use in an electrical distribution system. The device includes a plurality of line terminals and a plurality of load terminals configured to be coupled to the plurality of line terminals in a reset state. A detector circuit is coupled to the plurality of line terminals. The detector circuit is configured to generate a detection signal in response to detecting at least one predefined perturbation in the electrical distribution system. A circuit interrupter assembly is coupled between the plurality of line terminals and the plurality of load terminals. The circuit interrupter assembly is configured to decouple the plurality of line terminals from the plurality of load terminals in response to the detection signal. An end-of-life mechanism is coupled to the detector circuit. The end-of-life mechanism is configured to permanently decouple the plurality of line terminals from the plurality of load terminals in the absence of an intervening signal.

Abstract: The present invention is directed to a protective device that includes a plurality of line terminals and a plurality of load terminals, the plurality of load terminals including a plurality of hot load terminals and a plurality of neutral load terminals. The device also includes a circuit interrupter having four sets of moveable contacts, the four sets of moveable contacts being configured to couple the plurality of line terminal to the plurality of load terminals in a reset state and to decouple the plurality of line terminals from the plurality of load terminals in a tripped state. A test circuit includes an end of life detection circuit coupled to the plurality of line terminals or the plurality of load terminals by a switch mechanism associated with the four sets of moveable contacts.

Abstract: An apparatus for ground fault current interrupter with overall end-of-life indication and shutdown protection function includes a first silicon-controlled rectifier, a reverse unit, a test switch unit and a ground fault current interrupter. The ground fault current interrupter includes a second silicon-controlled rectifier, a switch unit, a switch control unit and a rectifier filter unit. When a test current leakage signal is generated, a drive power is provided to the reverse unit, and the input power supply generates a current leakage phenomenon. If the ground fault current interrupter fails, then the second silicon-controlled rectifier will not be triggered, which makes the reverse unit trigger the first silicon-controlled rectifier, such that the rectifier filter unit outputs a DC power flowing through the first silicon-controlled rectifier to interrupt a power supply of the switch control unit.

Abstract: A circuit is disclosed for disconnecting a power source upon the detection of a leakage current comprising a power cable having an insulated first and a second wire. The power cable has a conductive shield surrounding the first and second wires with a drain wire electrically contacting the conductive shield. A disconnect switch is interposed between the power source and the power cable. A primary circuit controls the disconnect switch. A secondary circuit is connected to the drain wire for sensing a leakage current between the conductive shield and one of the first and second wires. An optical switch interconnects the primary circuit and the secondary circuit for opening the disconnect switch upon the secondary circuit sensing a leakage current.

Abstract: A GFCI device with circuit condition detection function includes a leakage current detection circuit, a disconnect mechanism, a reset mechanism, a circuit condition detection and control circuit, and a selection switch. The disconnect mechanism includes a first SCR controlled by the leakage current detection circuit. The circuit condition detection and control circuit includes a first control circuit and a second control circuit. When the first control circuit is connected to an anode of the first SCR by the selection switch, it provides an intermittent simulated leakage current to the leakage current detection circuit, and the leakage current detection circuit provides a trigger signal for a control gate of the first SCR, so that the first control circuit generates an intermittent simulated leakage current. When the leakage current detection circuit is not operational to generate the trigger signal, the first control circuit generates a control signal to disable the GFCI device.

Abstract: A circuit that includes a single grounded fault sensing transformer coupled to a resonant circuit that produces an output signal used by a microcontroller to determine a load current flowing through at least two conductors passing through the center of the sensing transformer. The microcontroller pings the resonant circuit, causing an impulse disturbance at the output signal, and the microcontroller calculates the inductance component of the resonant circuit based on the frequency of the decaying output signal. The microcontroller calculates the resistive core loss as a function of a known resistance of the resonant circuit, a known capacitance of the resonant circuit, the calculated inductance, and the determined rate of decay of the output signal. The calculated resistive core loss is compared to a table or to a polynomial function that characterizes known resistive core losses with known load currents to determine the load current corresponding to the calculated resistive core loss.

Abstract: A ground fault interrupter to be used by utility company while effecting repairs to the electrical service for a building is positioned to interrupt the power supply to the building in case of a detected ground fault and utilizes a sensor for detecting the fault current at the service entrance to a building; a contact switch, selectively movable between open and closed positions, mounted for temporary use in series with said power supply to the building; and a microprocessor based circuit for measuring and evaluating fault current detected by the sensor and controlling the selective movement of the contact switch between its open and closed positions.

Abstract: The present invention is directed to an electrical wiring system for use in an AC electrical power distribution circuit including at least one first AC power conductor disposed between an upstream AC power element and a device box and at least one second AC power conductor disposed between the device box and a downstream AC power element. The at least one first AC power conductor and the at least one second AC power conductor are routed into an interior portion of the device box and accessible via a front open face of the device box. The system includes a connector device including a connector housing having a plurality of connector contacts disposed therein. The plurality of connector contacts are coupled to termination structures configured to couple the at least one first AC power conductor and the at least one second AC power conductor to corresponding contacts of the plurality of connector contacts. An electrical wiring device includes a device housing having a front portion and a rear portion.

Abstract: A switching circuit, e.g. an RCD, comprises a pair of mechanical contacts (M) in an alternating current electricity supply (N, L) and circuit means (SCR) for opening the contacts to cut off the supply in response to a switching signal (S). The switching circuit includes further circuit means (Rs, Cs, D2, D3, Q1, Q2) for defining successive periods of time (“activation windows”) during which the magnitude of the supply voltage is not at a maximum and allowing the contacts to open in response to a switching signal only during such windows.

Abstract: A method for monitoring electric isolation of a high voltage DC bus to detect ground isolation faults includes monitoring voltage differentials between a positive DC electric power bus and a negative DC electric power bus and a chassis ground. Electrical isolation between each of the positive and negative DC electric power buses and the chassis ground is monitored using a ratio of the voltage differentials.

Abstract: A detection and alarm circuit includes a transformer, a rectifier, and an alarm. A first input terminal of the transformer is connected to a ground terminal of an electronic device, and a second terminal of the transformer is grounded. A first output terminal of the transformer is connected to a first input terminal of the rectifier, and a second output terminal of the transformer is connected to a second input terminal of the rectifier. A first output terminal of the rectifier is connected to a first terminal of the alarm. A second output terminal of the rectifier is connected to a second terminal of the alarm.

Abstract: A ground fault detection system for an electrical system is disclosed. The electrical system may have a first and a second electrical component and a controller, and the second electrical component may be coupled to the controller. The ground fault detection system may include a ground fault detection module integrated in the first electrical component. The first electrical component may be isolated from the second electrical component. The ground fault detection system may further include a data link configured to establish a data communication between a controller and the ground fault detection module. The ground fault detection module may be configured to activate a mode of operation for the first electrical component if a ground fault associated with the first electrical component is identified.

Abstract: An ungrounded or floating DC electrical power distribution system may experience a single line to ground fault. Such a fault may not disrupt operation of the system, but its presence may raise a risk of additional problems if left uncorrected. A system for progressively grounding the ungrounded system may be initiated when a line to ground fault is suspected based on the voltage difference measured to a common chassis point. As grounding through successively lower impedance proceeds, fault current may increase and detection of severity of the line to ground fault may be more readily achieved, thus facilitating localization of the fault. Localization may be achieved through an analysis of direction of capacitive currents in isolatable zones of the system.

Abstract: An aircraft electrical appliance is provided with a ground-fault-interruption device (50) for protecting it in the event of problematic current loss due to, for example, a compromise in electrical insulation. The device (50) has a GFI circuit (60) comprising a current differential determiner (70), a trigger (80) that is activated upon the current differential corresponding to ground-fault situation, and an interrupter (90) that interrupts power supply to the appliance upon the trigger (80) being activated. The GFI circuit (60) is electrically independent of electrical controller components of the appliance, thereby avoiding expensive software configuration and confirmation.

Abstract: An electrical device having thermal overload protection detects an abnormal temperature of the current carrying conductors, and causes a current imbalance so that a ground fault circuit interrupter (GFCI) triggers, thereby cutting off current flow and preventing thermal overload.

Abstract: A differential protection device comprising: differential current measuring means, processing means connected to the measuring means and comprising operating rating selection means and time delay selection means to select tripping curves, actuating means, and test means connected to the measuring means. In the protection device the test means are associated with the operating rating selection means and with the time delay selection means to select a minimum or reduced operating rating and to select a minimum or reduced time delay when said test means are actuated.

Abstract: A circuit tests the health of a ground-neutral transformer within a ground fault circuit interrupter. This test can include testing both the ground-to-neutral detection circuitry and the differential current detection circuitry. The test circuit provides a conductive path through the respective cores of a differential transformer and the ground-neutral transformer of the GFCI device. A closed loop induces current from the differential transformer, which creates a current imbalance through the differential transformer. In a properly working device, the circuit breaker will trip, confirming the health of the ground-neutral transformer portion of the GFCI.