Abstract: The present disclosure provides a contact actuating unit for an electrical circuit breaker. The contact actuating unit includes an electro-mechanical device. An actuator of the electro-mechanical device is connected to a contact arrangement in the electrical circuit breaker. The contact actuating unit further comprises a control unit. The control unit is configured to control the electro-mechanical device to move the actuator and to bring the contact arrangement from a first to a second position. The contact actuating unit further includes a command feed forward or motion trajectory and feed forward controller, configured to provide one or more data signals. At least one of the provided data signals is indicative of a predetermined force and/or torque value, adapted to command the control unit to move the contact arrangement with the actuator to a predetermined position.

Abstract: A smart accessory device includes an actuator and is designed to be used to actuate an operating mechanism of a circuit breaker in order to either open or close the separable contacts of the circuit breaker. The accessory can be one of a shunt trip, spring release, or under voltage release device. The actuator includes a solenoid and plunger. The accessory determines the operating condition of the actuator based on how much current flows through the coil when the power source provides power to the accessory device, and continually executes a coil diagnostic to determine the operating condition of the coil while power is being provided to the accessory device. If the accessory fails to trip the circuit breaker when required, the accessory can determine whether the failure was due to either of the solenoid or the plunger.

Abstract: A fan motor stopping apparatus includes a conversion circuit that converts alternating-current voltage supplied from an alternating-current power supply into direct-current voltage, a smoothing capacitor that is connected to a fan motor included in an air conditioner and smooths the direct-current voltage from the conversion circuit, a voltage detection circuit that detects a voltage across the smoothing capacitor, and a fan motor shutdown circuit that suspends the fan motor in operation when the voltage detection circuit detects a voltage less than or equal to a threshold that is preset for suspending the operation of the fan motor.

Abstract: Solid state and hybrid circuit protection devices include improved chemical, static discharge and impact resistant housing construction, arc-free switching operation, secure terminal assemblies and thermal management features. The solid state and hybrid circuit protection devices are ignition protected and avoid possible explosions and therefore obviate a need for conventional explosion-proof enclosures to ensure safe operation of an electrical power system in a potentially explosive environment.

Abstract: Passive monitoring the integrity of current sensing devices and associated circuitry in GFCI and AFCI protective devices is provided. A protection circuit interrupter employs a capacitively coupled noise signal obtained by an arrangement of one or both of line side arms relative to a Rogowski coil. The noise signal is monitored while the line and load sides of a protective circuit interrupter are disconnected, and the connection of the line and load sides disabled if the noise signal fails to correlate sufficiently to a reference noise cycle. When the line and load sides are connected, the RMS value of the observed current signal is monitored such that the line and load sides are disconnected if the observed current signal fails to meet an RMS threshold. The observed current signal is compensated by subtracting the reference noise cycle prior to monitoring for the fault condition applicable to the protective device.

Abstract: A battery charging method includes: acquiring a current static voltage of a battery in a current charging stage, and determining the maximum charging current matching with the current static voltage, during staged charging of the battery; and charging the battery according to the maximum charging current. The charging speed can be guaranteed, and the overvoltage protection cannot be triggered during each charging stage, thereby preventing damages to battery cells.

Abstract: A line protector circuit comprises an external side switch circuit coupled to an external circuit node of the line protector circuit, an internal side switch circuit coupled in series to the external side switch circuit and an internal circuit node of the line protector circuit, a high supply circuit node and a low supply circuit node, and switch control circuitry configured to deactivate the internal side switch circuit and divert a bias current from the external side switch to the low supply circuit node when the external voltage exceeds a high supply voltage of the high supply circuit node.

Abstract: The semiconductor circuit breaker includes a semiconductor switch unit connected to an AC circuit, and a phase control unit that controls conduction and non-conduction of the semiconductor switch unit by the control signal. The phase control unit includes an accident detection unit to detect an accident based on a current detected from the AC circuit, a zero point detection unit to detect a current zero point based on the current detected from the AC circuit, and a control signal output unit to output the control signal for setting the semiconductor switch unit to be non-conductive when the accident detection unit detects the accident or when the zero point detection unit detects the current zero point in response to a command to cut off the current.

Abstract: It is disclosed a motor thermal protection device and operation method thereof. The motor thermal protection device utilizes a power supply of a motor for power supplying and comprises: a capacitor timing circuit, configured to time after the motor is powered off; a power-off time determining unit, configured to perform a reading operation of reading an output voltage of the capacitor timing circuit after the motor is powered on, and determine a power-off time from when the motor is powered off to when the motor is powered on according to the output voltage; and a heat accumulation calculating unit, configured to calculate a remaining heat accumulation when the motor is powered on according to the power-off time and a heat accumulation when the motor is powered off.

Abstract: An electrical switch including a neutral contact adjustment system adapted for adjusting a position of a neutral contact opening surface relative to at least one phase contact opening surface such that the neutral contact adjustment system has a first operating state which is adapted to provide a simultaneous break operation in which a movable neutral contact disconnects simultaneously with at least one movable phase contact during an opening event, and a second operating state which is adapted to provide a late-break operation in which the movable neutral contact disconnects later than the at least one movable phase contact during the opening event.

Abstract: Systems and methods for fault detection and protection in electric power systems that evaluates electromagnetic transients caused by faults. A fault can be detected using sampled data from a first monitored point in the power system. Detection of fault transients and associated characteristics, including transient direction, can also be extracted through evaluation of sample data from other monitored points in the power system. A monitoring device can evaluate whether to trip a switching device in response to the detection of the fault and based on confirmation of an indication of detection of fault transients at the other monitored points of the power system. The determination of whether to trip or activate the switching device can also be based on other factors, including the timing of receipt of an indication of the detection of the fault transients and/or an evaluation of the characteristics of the detected transients.

Abstract: Passive monitoring the integrity of current sensing devices and associated circuitry in GFCI and AFCI protective devices is provided. A protection circuit interrupter employs a capacitively coupled noise signal obtained by an arrangement of one or both of line side arms relative to a Rogowski coil. The noise signal is monitored while the line and load sides of a protective circuit interrupter are disconnected, and the connection of the line and load sides disabled if the noise signal fails to correlate sufficiently to a reference noise cycle. When the line and load sides are connected, the RMS value of the observed current signal is monitored such that the line and load sides are disconnected if the observed current signal fails to meet an RMS threshold. The observed current signal is compensated by subtracting the reference noise cycle prior to monitoring for the fault condition applicable to the protective device.

Abstract: The present invention generally directed to arc detection circuits or systems that help prevent fire damage to solid state (LED) based light sources by providing an arc detection system that can be used to detect acing in LED based light fixtures. Once the arcing is detected, power can be quickly turned off to the lighting system. One arc detection circuit according to the present invention comprises a high pass filter circuit arranged to accept an electrical signal with an arc current component having one or more arcing events and a direct current (DC) component, wherein the high pass filter passes only the arc current component. An arc detection circuit is included that accepts the arc current component and filters out arcing events below a threshold. Wherein the arc detection circuit provides an arcing signal with arcing events above said threshold. A microcontroller is also included that accepts the arcing signal to generate control signals based on the arcing signal.

Abstract: A system and method for monitoring the health of a heater connected to a power supply by first and second power leads which conduct an inlet and outlet current, respectively. The system includes an injection transformer with a number of primary turns that are inductively coupled to the first power lead, a signal generator configured to generate and supply a time-varying injection signal to the primary turns thereby imposing the time-varying injection signal on the inlet current, and a signal reader configured to receive a diagnostic signal from the heater, filter the diagnostic signal to pass a frequency associated with the time-varying injection signal, and produce a heater capacitance signal that is indicative of a capacitance value of the heater, where the heater capacitance signal is indicative of the health of the heater.

Abstract: A control method for a user interface system may include receiving an input signal, receiving a temperature signal indicative of a temperature, generating a baseline signal based on at least one among the input signal and the temperature signal, calculating an error signal based on a difference of the input signal and the baseline signal, and modifying the baseline signal based on the error signal.

Abstract: A power contact electrode plasma therapy circuit includes a pair of terminals adapted to be connected to a set of switchable contact electrodes of a power contact. A plasma ignition detector is configured to detect an electrical parameter over the switchable contact electrodes indicative of the formation of plasma between the switchable contact electrodes and output a plasma ignition signal based on the electrical parameter as detected. A plasma burn memory is configured to receive and store the plasma ignition signal. A controller circuit is configured to receive from the plasma burn memory the plasma ignition signal, start a time based on receipt of the plasma ignition signal, and upon the timer meeting a time requirement, output a plasma extinguish command. A plasma extinguishing circuit, configured to bypass the pair of terminals upon receiving the trigger signal to extinguish the plasma between the switchable contact electrodes.

Abstract: According to some embodiments, a device includes: a magnetic field current sensor magnetically coupled to a conductor and configured to generate a magnetic field signal having a magnitude responsive to a current flowing through the conductor; a shunt interface having first and second input terminals electrically coupled to ends of a shunt disposed along the conductor, the shunt interface configured to generate a shunt signal having a magnitude responsive to the current flowing through the conductor; and a diagnostic circuit configured to receive the magnetic field signal and the shunt signal and to generate a fault signal based on a comparison between the magnitude of the magnetic field signal and the magnitude of the shunt signal.

Abstract: The present disclosure discloses a current detecting circuit of a power converter, which includes a transformer including: a magnetic core, a primary winding and a secondary winding, the primary winding and the secondary winding being coupled through the magnetic core, and a combination of the primary winding, the secondary winding and the magnetic core being used to transmit a main power of the power converter, the current detecting circuit includes: an auxiliary winding coupled to the secondary winding, the auxiliary winding and the secondary winding having the same number of turns and their dotted terminals being connected; and an impeder, one end thereof being coupled to the auxiliary winding to form a series branch, which is coupled in parallel to the secondary winding, and a terminal voltage of the impeder after being filtered being proportional to a magnitude of an output current of the power converter.

Abstract: Embodiments of the present disclosure provide a protection circuit and an air conditioner, which are applied to the field of air conditioner technologies and used to protect an indoor unit. The protection circuit provided by the embodiments of the present disclosure includes: a positive temperature coefficient thermistor; a signal input terminal; and a communication module; wherein a first end of the positive temperature coefficient thermistor is connected to the signal input terminal, and a second end of the positive temperature coefficient thermistor is connected to the communication module.

Abstract: The present disclosure relates to an earth leakage breaker having a leakage current limiting function, and the earth leakage breaker is provided to implement leakage current limiting parts at both ends of an earth leakage breaker part so that both an input terminal and an output terminal are each provided with the leakage current limiting function to increase leakage current limiting efficiency.

Abstract: The present invention provides a rotation angle detection method and device thereof. The method includes calculating an estimated value of a rotation angle of a motor shaft during rotation according to a second rotation angle; determining an actual range of the rotation angle according to the estimated value of the rotation angle and a detection error of the second angle sensor; determining optional values of the rotation angle based on a relative relationship between a first rotation angle and the estimated value; determining an actual rotation angle of the motor shaft, based on a value falling within the actual range of the rotation angle among the optional values, and determining an actual rotation angle of the output shaft according to the actual rotation angle of the motor shaft. The present invention can improve the measurement accuracy of the rotation angles of the output shaft of the rotating mechanism.

Abstract: A circuit breaker system is disclosed in the present application. The circuit breaker system includes a housing to hold an electrical interrupter within an internal region separated from an external ambient region. The electrical interrupter includes at least a first pair of electrical contact elements that are movable between open and closed positions. A voltage limiter, such as a metal oxide varistor (MOV), is connected across the pair of electrical contact elements to receive and dissipate a transient voltage when the first pair of electrical contacts is moved from a closed position to an open position, thereby reducing undesired arcing and premature wear or erosion of certain electrical components.

Abstract: An RF sensing apparatus configured for use with a plasma processing chamber includes a penetration unit opened in an up/down direction, a main return path unit surrounding all or a portion of the penetration unit, and a secondary return path unit located between the penetration unit and the main return path unit, spaced apart from the main return path unit, and surrounding all or a portion of the penetration unit. The main return path unit and the secondary return path unit include a path through which a current flows in one of the up/down directions.

Abstract: A method for determining the wear on a contact element of an electrical switch, for example, of a switching installation for high or medium voltage, includes recording electrical values which represent an electrical variable, which is relevant to an arc occurring at the switch during a switching operation, as a function of time, and calculating a wear value, which represents the wear on the contact element, from a plurality of wear contribution values. The wear contribution values are calculated from a plurality of subsets of the recorded electrical values using a plurality of wear contribution calculation rules, with the result that each of the wear contribution values is calculated from a respective one of the subsets of values according to a respective one of the wear contribution calculation rules. At least two of the wear contribution calculation rules differ from one another.

Abstract: An overvoltage protector having a housing and at least one overvoltage limiter arranged in the housing, especially a gas-filled surge arrester (1), a suppressor diode (2) or a varistor. The functional ability and the state of the overvoltage protector can be controlled during operation by associating a monitoring component with the overvoltage limiter which detects a current (i) flowing over the overvoltage limiter component, and by providing an evaluation unit that evaluates the signal of the monitoring component.

Abstract: An electronic protection device for protecting at least one electrical load, connectable to the protection device, whereby the electronic protection device has an input terminal and an output terminal, and whereby the protection device includes a fuse element, which is thermally self-resetting, and whereby the fuse element is provided and set up to conduct or limit a first current as a function of a fuse element temperature, whereby a limiting component is provided to limit the first current, and whereby the limiting component has a first transistor that is connected in series to the fuse element and a monitoring circuit that influences the first transistor. The monitoring circuit blocks the first transistor when the first current reaches or exceeds a predefined maximum current value and unblocks it when the first current reaches or falls below a predefined reset current value.

Abstract: A protective system far a power transformer having a neutral line connected to ground where large currents can flow in the neutral line due to electro-magnetic disturbances. The system includes circuitry for: (a) sensing the current level in the neutral line and whether it exceeds a predetermined threshold for a predetermined period; and (b) sensing and processing the harmonic content of the load current and determining the existence of certain relationships of the “even” and “odd” harmonics. Signals, including alarms, indicative of excessive conditions are produced. The system may also include circuitry for sensing the load current level and generating a signal alarm if the load level is above a given value when the harmonics and the DC current have values in excess of certain predetermined values.

Abstract: A solid-state fault current limiter including a current splitting reactor, comprising a system current input, a passive current output and a control current output. A voltage control reactor includes a first end and a second end, the first end coupled to the control current output and the second end coupled to the passive current output. A fault current trigger circuit coupled in parallel with the voltage control reactor and configured to open when a fault current, received by the system current input, exceeds a predefined trigger current. A transient voltage control circuit coupled in parallel with the voltage control reactor to receive the fault current.

Abstract: An electrical power distribution network may include a plurality of transformers and a local manager associated with a transformer. Each local manager may be configured to monitor and control a magnetic flux level in a magnetic flux core of the associated transformer. The electrical power distribution network may also include a central manager configured to receive magnetic flux level data from each local manager and control operation of each local manager in response to the magnetic flux level data.

Abstract: Physical layer device auto-adjustment based on power over Ethernet (PoE) magnetic heating. In one embodiment, information generated by a PoE module that is indicative of the PoE operation over the network cable (e.g., level of current, heating, etc.) is made available to the physical layer device (PHY). This information enables the PHY to infer a change in the level of inductance on the line. In response, the PHY can then adjust a characteristic of transmission by the PHY.

Abstract: A power circuit breaker is disclosed wherein an electric current is monitored by an electronic trip unit in order to detect an electrical fault. In an embodiment, a first magnetic device of the power circuit breaker, in the event of a fault being detected, is configured to be excited which, when it is excited, trips a trip mechanism via a plunger. As a result of tripping, the trip mechanism disconnects two contacts via which the current flows. The power circuit breaker of an embodiment includes a second magnetic device which is likewise able to be excited by the ETU and by which the trip mechanism is likewise able to be tripped.

Abstract: A protection and control system includes a first merging unit which obtains an electric variable from a transformer, and digitally converts the obtained electric variable to output the converted electric variable as first electric variable information to a first network, a plurality of first protection and control devices, each of which obtains the first electric variable information from the first merging unit through the first network, judges whether or not a system fault occurs, and outputs main trip information to the first network when that the system fault occurs is judged, and a second protection and control device which obtains the first electric variable information from the first merging unit through the first network, judges whether or not the system fault occurs in the zone to be protected of the electric power system.

Abstract: A fault current limiter (FCL) includes at least one magnetisable core member and at least one AC magnetomotive force source configured to generate a varying magnetic flux in at least a portion of the at least one magnetisable core member. At least one static magnetomotive force source is positioned to provide a magnetic circuit within at least part of the at least one magnetisable core member and the AC magnetomotive force source and the static magnetomotive force source are relatively positioned to be orthogonal to each other. Typically the static magnetomotive force source may be a permanent magnet and the AC magnetomotive force source configured to generate a varying magnetic flux in both of first and second spaced core members.

Abstract: An apparatus is provided for securing to and collecting power from an electrical conductor including a wire clamp that clamps and secures to an electrical conductor, a current transformer (“CT”) that clamps to the electrical conductor and collects power from the electrical conductor, and a housing that supports the wire clamp and the current transformer. According to various aspects, the apparatus may include a wire clamp including a compression post and clamp arms that surround and compress an electrical conductor in a closed position of the wire clamp, where each of the clamp arms includes pivot posts, and the clamp arms pivot between closed and open positions. According to other various aspects, the apparatus may include a split magnetic core that surrounds an electrical conductor in a closed position of the current transformer, where the split magnetic core includes pivot posts, and the split magnetic core pivots between closed and open positions.

Abstract: An inductive fault current limiter (1) has a normally conducting primary coil assembly (2) with a multiplicity of turns (3) and a superconducting, short-circuited secondary coil assembly (4), wherein the primary coil assembly (2) and the secondary coil assembly (4) are at least substantially coaxial with respect to each other and at least partially interleaved in each other. The primary coil assembly (2) has a first coil section (2a) and a second coil section (2b), wherein the turns (3) of the first coil section (2a) of the primary coil assembly (2) are disposed radially inside the secondary coil assembly (4) and the turns (3) of the second coil section (2b) of the primary coil assembly (2) are disposed radially outside the secondary coil assembly (4). The fault current limiter has an increased inductance ratio.

Abstract: Magnetic field current sensing devices, systems and methods are disclosed. In an embodiment, a current sensor includes a semiconductor die; an isolation layer disposed on the semiconductor die; at least one anchor pad disposed on the isolation layer; a current input and a current output galvanically isolated from the semiconductor die; at least one bond wire coupled to the current input and the current output, a longitudinal portion of the at least one bond wire disposed between the current input and the current output being stitched to the at least one anchor pad; and at least one sensor element arranged to sense a magnetic field induced by a current flowing in the at least one bond wire.

Abstract: A circuit breaker system for providing thermal protection to a conductor conducting current from a power source to a load. While the power source is connected to the load, a microcontroller is powered by the current passing through the conductor to thermally model the temperature of the conductor. If the microcontroller determines that the temperature of the conductor has risen to an undesirable or unsafe level, the circuit breaker disconnects the power source from the load and the current no longer passes through the conductor. With no current passing through the conductor, the microcontroller no longer receives power from the conductor. Instead, the microcontroller continues to model the temperature of the conductor as the conductor cools to an ambient temperature by receiving power from an energy storage device. Accordingly, the microcontroller continuously models the temperature of the conductor until the temperature of the conductor cools to the ambient temperature.

Abstract: An electrical circuit for protecting an electrical load from overload current is provided. The system includes a voltage transformer configured to receive AC mains voltage from an electric mains supply and further configured to apply reduced voltage to the electrical load. A control switch comprising metal contacts is connected to the voltage transformer. The control switch is configured to facilitate application of reduced value of AC mains voltage to the electrical load. A reduced value of current flowing through the electrical load is measured by a current transformer connected in series with the electrical load. The reduced value of current is then used for estimating a current consumption value in event of AC mains voltage being directly applied to the electrical load. A control signal is then used for disconnecting the electrical circuit if the estimated current consumption value is greater than threshold overload current value.

Abstract: The present invention may provide a surge current sensor and a surge protection system that deploys one or more surge current sensors. The surge current sensor may be placed on or near to a conduit, and it may be used for sensing the surge current conducted therein. The surge current sensor may include a current transformer and a processor. The current transformer may be used for receiving a magnetic flux generated by the surge current and transforming the received magnetic flux to a voltage. The processor may be coupled with the current transformer, such that it may be configured to generate a digital signal based on the voltage. Once the digital signal indicates that the magnitude of the surge current has exceeded a predefined threshold, the surge protection system may initiate a surge protection mechanism.

Abstract: An integrated circuit (IC) current sensor that self-calibrates to adjust its signal gain when employed in a current divider configuration is presented. The current sensor includes an integrated current conductor, a magnetic field transducer, a controllable gain stage and a calibration controller. The integrated current conductor is adapted to receive a portion of a calibration current. The calibration current corresponds to a full scale current. The magnetic field transducer, responsive to the calibration current portion, provides a magnetic field signal having a magnitude proportional to a magnetic field generated by the calibration current portion. The controllable gain stage is configured to amplify the magnetic field signal with an adjustable gain to provide an amplified magnetic field signal.

Abstract: A current sensor includes a magnetic balance sensor and a switching circuit. The magnetic balance sensor includes a feedback coil which is disposed near a magnetic sensor element varying in characteristics due to application of an induction field caused by measurement current and which produces a canceling magnetic field canceling the induction field. The switching circuit switches between magnetic proportional detection and magnetic balance detection. The magnetic proportional detection is configured to output a voltage difference as a sensor output. The magnetic balance detection is configured to output, as a sensor output, a value corresponding to current flowing through the feedback coil when a balanced state in which the induction field and the canceling magnetic field cancel each other out is reached after the feedback coil is energized by the voltage difference.

Abstract: A system comprising a magnetic actuator, a current transformer and operational electronics in a dual-coil circuit breaker. The system includes an inline, but non concentric, implementation of the primary and secondary coils to maintain a narrow width suitable for retrofitting in standard industrial rack mounted enclosures. The system further comprises a split core design that is integrated into an upper and lower plate which slide together and are retained by a secondary coil bobbin. Typically, the two parts of the split core can be manufactured into net shapes by utilizing a powder metal or metal injection molding process. Moreover, the split core design disclosed herein can reduce costs and time associated with manufacturing and assembly of the current transformer.

Abstract: A brushless fan motor control circuit assembly consists of a high-frequency filter circuit, a rectifier circuit, a power factor enhancing circuit, a current-limit and voltage regulation circuit and a brushless fan motor driving circuit. By means of the high-frequency filter circuit to suppress high frequency noises, the power factor enhancing circuit to enhance the power factor and to save power consumption, the current-limit and voltage regulation circuit to limit the current and to achieve overload protection, the brushless fan motor control circuit assembly controls the operation of a motor of an electric accurately and safely, avoiding fan vibration.

Abstract: A system comprising a magnetic actuator, a current transformer and operational electronics in a dual-coil circuit breaker. The system includes an inline implementation of the primary and secondary coils to maintain a narrow width suitable for retrofitting in currently designed industrial rack mounted enclosures. The system further comprises network connectivity allowing interrogation of the components for operational data associated with the component.

Abstract: A residual-current circuit breaker includes at least one summation current transformer through which at least one first lead and one second lead of a network to be protected are guided. At least one secondary winding is arranged on the summation current transformer and operatively connected at least indirectly with at least one energy storage element. At least one discharging resistor is switched in parallel with the energy storage element. The residual-current circuit breaker has a trip element which is operatively connected with break contacts in the at least one first lead and the at least one second lead. In order to reduce unexpected cut-offs of a network to be protected, the at least one discharging resistor includes a first partial resistor, and a second partial resistor switched in series with respect to the first partial resistor, with a least one electric signaling device operatively connected, at least indirectly, with the first partial resistor.

Abstract: A motor control circuit 1 for controlling driving of a plurality of motors is provided with a plurality of motor driver circuits 7 and 8 for controlling driving of the plurality of motors 3 and 4, a plurality of excess current detection circuits 39 and 40 each for detecting an excess current flowing through corresponding one of the plurality of motors 3 and 4 to determine which motor driver circuit among the plurality of motor driver circuits 7 and 7 caused the excess current. The motor control circuit further includes a nonvolatile memory 46 configured to receive detection results from the plurality of excess current detection circuits 39 and 40 and store information on which motor driver circuit among the plurality of motor driver circuits 7 and 8 caused the excess current.

Abstract: Certain exemplary embodiments can comprise an apparatus comprising: a current transformer adapted to provide a signal correlated to an amperage of an alternating current of a first phase of an electric circuit, the alternating current flowing through a circuit breaker; and a microprocessor adapted to receive the signal from said current transformer, and to cause the circuit breaker to trip responsive to the signal exceeding a predetermined threshold.

Abstract: An isolation-type AC fault current limited circuit is a current regulation circuit including a transformer and a conduction circuit. The transformer includes a primary winding coupled in series between a power supply input system and a load output system, and a secondary winding sharing a common iron core with the primary winding and electrically isolated therewith. The conduction circuit is connected to the secondary winding and includes a switch and a breaking element coupled in series. In the event that short circuit takes place on the power system, the breaking element induces great short circuit current of the primary winding and is fused to cut off conduction, so that the transformer becomes an open circuit to increase magnetizing reactance with high impedance to increase equivalent internal impedance of the power supply input system to limit fault current and allow circuit breaking devices of the power system to isolate short circuit.

Abstract: An electrical circuit for protecting an electrical load from overload current is provided. The system includes a voltage transformer configured to receive AC mains voltage from an electric mains supply and further configured to apply reduced voltage to the electrical load. A control switch comprising metal contacts is connected to the voltage transformer. The control switch is configured to facilitate application of reduced value of AC mains voltage to the electrical load. A reduced value of current flowing through the electrical load is measured by a current transformer connected in series with the electrical load. The reduced value of current is then used for estimating a current consumption value in event of AC mains voltage being directly applied to the electrical load. A control signal is then used for disconnecting the electrical circuit if the estimated current consumption value is greater than threshold overload current value.

Abstract: A protective device is disclosed for combination with an electrical switching device including a main current line or for integration in such a switching device. In at least one embodiment, the protective device includes a switching element and a switching apparatus, which is provided for the actuation of the switching element and is influenced by a current flow through the main current line. In at least one embodiment, in order to influence the switching apparatus, a current transformer is integrated in the main current line and an electrical resistance of a secondary winding surrounded by the current transformer can be measured. A method for operating a protective device is also disclosed wherein the switching apparatus is triggered so as to actuate the switching element if the measured resistance reaches or exceeds a predetermined or predeterminable threshold value.