Abstract: A circuit protects a power conversion system with a feedback control loop from a fault condition. The circuit has an oscillator having an input for generating a signal with a frequency and a timer connected to the oscillator input and to the feedback control loop. The timer disables the oscillator after a period following the opening of the feedback control loop to protect the power conversion system.

Abstract: Current limiting using capacitor charge measurement to limit the supply current or load current of a circuit, or the current flowing through a device or switch, to prevent the time average current in the switch from exceeding a certain safe level. A replica circuit is used to provide a scaled version of the current in the main switch. The current output of the replica circuit is used to charge a capacitor during the first period of the clock signal so that the capacitor voltage, at any time during the on time, is proportional to the time integral of the current output of the replica circuit, and thus, the time integral of the current in the main circuit. The capacitor voltage, in turn, is compared with a known voltage to determine whether the charge that has flowed through the main switch has exceeded a predetermined maximum. The output of the comparator may be used in various ways, including as a control of the clock duty cycle to limit the on time of the main switch. Various embodiments are disclosed.

Abstract: A method and device for monitoring insulation and fault current in an electrical alternating current network. The differential current formed by vectorial addition is detected between at least two network conductors. Load-cut occurs when the differential current exceeds a specific threshold value. In order to increase safety and to protect human beings, the amount of alternating current contained in the differential current is detected as a first network variable, and the network alternating current between at least both network conductors and between at least one network conductor and an equipotential bonding conductor or a neutral conductor is detected as a second network variable.

Abstract: The present invention is a load balancing and distributing switch-on/turn-on control for a circuit breaker, an appliance, a device, or an apparatus wherein each switch-on device on a circuit breaker, appliance, device, or apparatus generates and provides a turn-on time delay up to a maximum turn-on time delay so that the turn-on times and respective loads after a power failure from all circuit breakers, appliances, devices, and/or apparatuses are distributed and/or balanced over a turn-on period. The present invention distributes and balances the load and consumption by various appliances, devices, and apparatuses at the time of initial power up after a power failure. The present invention also distributes the turn-on times of the various appliances, devices, and apparatuses at the initial power up time. A circuit system and method for load balancing and distributing switch-on control of an operating device.

Abstract: A leakage current protection device, such as a ground fault circuit interrupter (GFCI), is provided that can be used in single phase or polyphase systems, with a range of input voltages from 70 to 264 volts AC, frequencies of 50 or 60 hertz, and ground fault trip currents of 6 to 30 milliamperes. A leading power factor circuit is connected to the secondary winding of the GFCI differential transformer to permit the magnetic circuit to respond to pulsating DC signals. Provision is made for continuing to provide GFCI protection in the event of an open neutral lead, with a timing circuit to prevent current flow to the ground lead until current flow in the neutral lead is completely discontinued. Various types of circuit interrupting devices, such as a circuit breaker or a power converter, may be selectively utilized.

Abstract: A method for limiting a switching current and limiting a voltage drop across a circuit includes the steps of limiting a current sent from a power source to a switching device during a turn on time of the switching device by disposing an inductor device in series between the power source and said switching device and returning flux energy stored in said inductor device to the power source during a turn off time of the switching device.

Abstract: A protection device for monitoring current in a power cable to an electrical device and for controlling a remotely located starter for the electrical device in response to a system controller. The device includes a transformer magnetically linked with the power cable to produce a voltage signal in response to the presence of a changing current within the power cable. An input circuit located in a single housing together with the transformer is electrically connected to the transformer so as to receive the voltage signal. The input circuit produces, in response to the voltage signal, either a first signal or a first circuit condition at the output terminal of the input circuit, representative of the changing current in the power cable. A switch circuit also in the same container with the transformer has a terminal for sensing either a second signal or a second circuit condition of the remotely located system controller.

Abstract: A piloting circuit comprises a circuit branch which is intended to be connected to a DC voltage supply source in such a way as to receive a voltage of predetermined polarity, and in which the drain-source path of a (first) MOSFET transistor intended to receive an on-off piloting signal on its gate is connected in series with the load, a current recirculation diode connected in parallel to the load, and protection devices operable to prevent damage to the MOSFET transistor and/or the diode in the event of polarity reversal of the supply voltage. The protection function is achieved of an electronic switch disposed in series with the recirculation diode and piloted in such a way as to prevent the passage of current in this diode if a supply voltage of reversed polarity with respect to the predetermined polarity is applied to the said circuit branch.

Abstract: Electrical equipment is safeguarded from damage due to faults by a circuit that provides several levels of protection. A semiconductor switch and a current sensor are placed in series with the electrical equipment. When the current to the equipment exceeds a first threshold for a predefined period of time, the semiconductor switch is rendered non-conductive until the circuit is specifically reset. When the current to the equipment exceeds a greater second threshold, a pulsed signal alternately places the semiconductor switch in conductive and non-conductive states so that the average current applied to the equipment is within an acceptable level. Should the current exceed an even greater third threshold, the semiconductor switch is immediately rendered non-conductive until the circuit is manually reset.

Abstract: A timer-thermal shutoff apparatus can control and protect an electrical appliance. The timer-thermal shutoff apparatus comprises a housing; male connector extending from the housing; female receptacle to receive a male connector from one or more electrical appliances; timer device; and thermal safety device. The timer device and thermal safety device are connected in series with the male connector and female connector receptacle to form a current path. The electrical appliance is in series with the timer device and thermal safety device. The timer device can control off-on switching and cycles for the electrical apparatus connected to the timer-thermal shutoff apparatus, and the thermal safety device providing thermal overload protection if at least one of the timer-thermal shutoff apparatus and electrical appliance reach a temperature so the thermal safety device opens the current path to protect at least one of the timer-thermal shutoff apparatus and electrical appliance.

Abstract: An arc fault detector, as a stand alone device or in combination with a circuit interrupting device such as a ground fault circuit interrupter (GFCI), protects from potentially dangerous arc fault conditions. The device utilizes line side and load side pickup coils to distinguish between arc faults occurring on the line or load side. An arc fault circuit interrupter (AFCI) circuitry portion of the device shares components from the GFCI circuitry portion, and utilizes the electromechanical power carrying portion of the GFCI, including AC line disconnect circuitry and a power supply. The AFCI employs quantitative detection using variable gain control in combination with either a load disconnect or audible/visual alarm indication. The device also includes a timer circuit, which permits the user to temporarily inhibit or disable the arc detection, and selective frequency filtering permitting arc detection in the presence of power line carrier communications.

Abstract: A combination current sensor and relay has an improved housing. In one aspect, the housing includes light emitting diodes on an upper surface that indicate open circuit and short circuit conditions. In another aspect, the housing includes a securement structure for a circuit board that includes the transformer and switches for device operation, together with aligned openings therein for routing wires to external devices. In another aspect, a multiple position switch is included on the upper surface that indicates multiple modes of operation of the device. In another aspect, the housing may be assembled in multiple parts by affixing a first portion to a support, a circuit board to the first portion, and a second portion to the first portion. In another aspect, the housing is suitable for engagement to alternatively a junction box and a duplex box. In another aspect, the configuration of the upper surface provides usability advantages.

Abstract: An electronic protective relay emulates an electromechanical protective relay so that operation of the two types of relays can be coordinated in providing protection in an electric power distribution system. The electronic protective relay incorporates a digital processor which increments a variable delay tally as an inverse current function and a fixed delay tally by a corresponding proportionate amount. During each running of the routine, only the smaller of the two tallies is increased so that they are forced to track one another. When both tallies reach a trip value, a trip signal is generated. The processor also applied a reset function when the measured current is below a pickup value. In accordance with the preferred reset feature, the variable delay tally is reduced using an inverse current function and the fixed delay is reduced by the same amount.

Abstract: A protection circuit (30) for a Traveling Wave Tube having multiple tone operation. The protection circuit (30) is a dual sensor (52, 54) arrangement. One sensor (52) is an operational amplifier circuit (56) having a short time constant and a high threshold current. The first sensor (52) provides protection against short time scale faults. The second sensor (54) is an operational amplifier circuit (58) having a time constant higher than the first sensor (52) and a lower current threshold than the first sensor (52) to provide protection against long time scale events. The two sensors (52 and 54) are logically “OR”ed with each other and eliminate spurious shutdowns and circuit damage.

Abstract: A circuit breaker system 10 using electronic trip units 35. The electronic trip units 35 are coupled to a communications bus 30 whereby the electronic trip units 35 can be reconfigured, controlled, and/or monitored by a central computer 20. Further, the electronic trip units are coupled to a separate control power supply line 50 and to a zone selective interlock system 70 . The zone selective interlock system 70 is configured to provide tripping delays to circuit breakers located upstream from a detected fault.

Abstract: A circuit arrangement is described for monitoring an electronic tripping device for low-voltage switches having a microprocessor device which, in conjunction with a digital-analog converter, evaluates an overcurrent so that line power supply system. The microprocessor device (MPE) has a zero crossing comparator with which a constant test current pulse is transmittable, at zero crossings, to the electronic tripping device via an additional current transformer winding to measure the amplitude. In the case of deviations from the setpoint value, (re)calibration or actuation of the line tripping contacts, with an alarm signal being emitted, takes place.

Abstract: A circuit breaker trip unit with user-adjustable sensitivity to current spikes (22) includes a user-adjustable switch (30), a current sensor (32), an analog-to-digital (A/D) converter (34), a microprocessor (36), and a power supply (37). The current sensor (32) is electrically connected to the distribution circuit (10) and provides analog signals indicative of current measurements in the distribution circuit (10) to the A/D converter (34). The A/D converter (34) converts the analog signal to a digital line signal and presents the digital line signal, via a bus (38), to the microprocessor (36). The user-adjustable switch (30) is arranged to provide a signal indicative of a limit value, via a bus (40), to the microprocessor (36). The microprocessor (36) comprises a plurality of registers (42-48) and ROM (50) internal thereto. The ROM (50) includes trip unit application code, e.g., main functionality firmware, including initializing parameters, boot code, and a short circuit protection algorithm.

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 method and apparatus for providing a more reliable protection device and an improved PIC power integrated switch. Accordingly, the over-temperature status of the switch as well as the overcurrent status of each of a plurality of ports of the switch are detected. If there is over-temperature, ports with the overcurrent status are identified as a potential cause. These ports are then switched off. After a predetermined waiting time period during which the switch temperature is expected to decrease, the over-temperature status of the switch is again checked. If the over-temperature disappears, then the ports with non-overcurrent status remain on. However, if the over-temperature persists, then all of the ports are turned off. The improved PIC switch thus increases the dynamic operation range of the conventional PIC switch, while ensuring normal operations.

Abstract: A protection device for monitoring current in a power cable to an electrical device and for controlling a remotely located starter for the electrical device in response to a system controller. The device includes a transformer magnetically linked with the power cable to produce a voltage signal in response to the presence of a changing current within the power cable. An input circuit located in a single housing together with the transformer is electrically connected to the transformer so as to receive the voltage signal. The input circuit produces, in response to the voltage signal, either a first signal or a first circuit condition at the output terminal of the input circuit, representative of the changing current in the power cable. A switch circuit also in the same container with the transformer has a terminal for sensing either a second signal or a second circuit condition of the remotely located system controller.

Abstract: An efficient, economical circuit which is easily added to existing modular or integrated pulse-width modulator circuits, e.g. switching power supply regulator circuits, having an fault comparitor which disables the pulse-width modulator when an overload error condition is detected for a time which exceeds a first RC time constant, and restoring the operation of the pulse-width modulator after a second R′C time. The differing RC and R′C time constants are provided by varied resistor circuit paths established by the state of the fault comparitor. The topology and economy of parts provide a current limiter which facilitates miniaturization and circuit integration.

Abstract: A self-powered multiple phase circuit protection device including a plurality of current transformers connected in parallel with each other and associated with one phase of a multiple phase load for providing signals representative of the current flowing in an associated phase. A first switch can be actuated to interrupt power to the multiple phase load, and a fault determining circuit is connected to the circuit transformers and to the first switch for actuating the switch during at least one predetermined condition of the current signals. A second switch can be automatically actuated to reconnect power to the multiple phase load. The fault determining circuit has a timer for delaying the actuation of the first switch, and a warning signal can be issued prior to actuation of the first switch so that the user can take corrective action.

Abstract: An overload protection circuit for a power switch has a delay element by means of which the voltage which is dropped across the power switch, the supply voltage and a temperature margin are evaluated in comparison with a maximum permissible depletion layer temperature. In the practical embodiment, a capacitor is provided which is charged and discharged by suitably controlled current sources. A disconnect signal for switching the power switch is produced by comparing the capacitor voltage with the temperature margin. The circuit ensures a safe disconnection in the event of a short condition in the load, even in the case of a periodic switching operation of the power switch.

Abstract: A protective relay receives current and voltage inputs, digitizes them and reduces the effects of high and low frequency noise. In the case of a distance relay, incorporated in the relay is a signal generator which generates "operate" and "restraint" sinusoidal signals. In the case of a current or voltage relay, operate is a digitized version of current (voltage) and restraint is a pre-specified constant. In all cases, a magnitude comparator, implemented using short (two sample) data window algorithms, compares the magnitude of the operate and restraint signals and outputs a trip condition signal. The trip condition output is limited to a finite number of values by a limiter system and sent to an adaptive trip counter system. The adaptive trip counter system employs trip counter processing, which determines whether a trip signal will be initiated, immediately or after a period of delay.

Abstract: For an electronic device having at least one power switch for each of two or more power sources such that the power switches can be selectively activated or deactivated depending on a signal supplied to them, a protection circuit having a current-sense circuit coupled to measure the current from the two or more power sources, and a latch for producing a switch deactivating signal and applying it to the switches in response to an over-current signal from the current-sense circuit can protect the switches and the electronic device from soft-short circuits and absolute short circuits. Bypass resistors coupled to the switches allow the electronic device to receive a small current ("pre-charge") before any of the switches are activated so that a comparator can test for the presence of various types of short circuits. Additionally, the precharging brings the electronic device to a higher voltage (as compared to no pre-charging) when one of the switches is activated, thereby helping to reduce in-rush currents.

Abstract: A solid state power controller for switching power on and off to an electrical load which also serves as a circuit protection device protecting the load and/or the wire connected between the load output terminal of the controller and ground from thermal damage due to current overload is shown. Upon current overload the controller interrupts current to the load in a time inversely proportional to the square of the magnitude of the overload. The controller also limits the load current to a selected maximum level by controlling the drain-source resistance of power MOSFETs (PS1-7) used for switching power. A secondary interrupt is provided in the event that the junction temperature of the MOSFETs has risen to a selected maximum level. A thermal memory feature is included for both interrupt signals. The controller is controlled by a single on/off input line (COMMAND) and provides both a status (STATUS) and trip (TRIP) output line. The status can be configured to monitor load voltage or load current flow.

Abstract: An electronic regulator for driving a power device connected to an output load having a first portion and a second protection portion, the first portion including a controlled switching element connected upstream of the power device and controlled by a timer adapted to be operated in a short circuit or overload situation of the device, such that the load current can flow in the power device in a pulsed state clocked by the timer.

Abstract: A current limiter is provided that includes a power switch for receiving input power from a power source and passing at least a portion of the input power to an output, a current sense mechanism coupled to the power switch for sensing current flowing through the current limiter and for providing a current flow signal related to the current flow through the current limiter, and a control mechanism coupled to the power switch that causes the power switch to reduce the current flow when the current flow signal indicates that the current flow exceeds a first current flow level. In one embodiment the current limiter may include a voltage sense mechanism that senses the voltage drop across the input to output of the device and use a reference voltage and a control loop to maintain the voltage drop relatively constant at all load currents.

Abstract: An overcurrent protection system containing (1) a current sensing means; (2) a first switch coupled to the current sensing means; (3) a voltage sensing means; (4) a PTC device; and (5) a second switch coupled to the voltage sensing means. In one type of system, the second switch is connected in series with a parallel combination of the first switch and the PTC device; and the voltage sensing means is connected in parallel with a series combination of (i) the second switch and (ii) the parallel combination of the first switch and the PTC device. In another type of system, the first switch, the PTC device and the voltage sensing means are connected in parallel with each other; and the second switch (i) is a switch which latches in the open position and (ii) is connected in series with the parallel combination of the first switch, the PTC device and the voltage sensing means.

Abstract: In a ground fault protecting apparatus of this invention, which protects a solar power generation apparatus from a ground fault, when a ground fault generated in a solar cell array is continuously detected for a period longer than a time T1, a gate block signal for stopping the operation of an inverter connected between the solar cell array and a load is output first. When the ground fault is continuously detected for a period longer than a time T2 (>T1), a disconnection instruction signal for disconnecting the inverter from the load is output to the disconnection unit. According to the ground fault protecting apparatus of this invention, a high ground fault detection sensitivity can be set. In addition, the solar power generation apparatus can be prevented from being unnecessarily stopped due to erroneous ground fault detection.

Abstract: A method of initializing short time and groundfault protection heat index accumulators to compensate for current flow during the time interval between the application of phase current and application of current measurement and protection algorithms in an electronic trip unit is presented. The electronic trip unit includes a microcontroller and associated ROM having trip unit application code, e.g., main functionality firmware, including initializing parameters, and boot code, stored therein and EEPROM having operational parameter code, e.g., encoded enumerations for parameters such as 50/60 Hz., UL/ANSI/IEC, etc., stored therein. The time internal comprises first and second time components.

Abstract: Protection circuitry for use with a modem is provided that detects excessive voltage between the tip and ring lines of a telephone subscriber loop when the modem is off-hook. When the over-voltage condition is detected, a switch is active, creating a circuit path that directs current away from the DC-holding circuit of the modem, thereby protecting the modem. The protection circuit of the present invention may be implemented using a minimal number of simple and inexpensive components.

Abstract: A microprocessor based overcurrent trip unit which generates trip signals as an adjustable function of current and time, has a visual representation of the trip function on a front panel with 2-color LEDs associated with the trip function serving as indicators of trip conditions when red, and of a selected programmable parameter when green. The green LEDs flash to indicate parameter selected for modification in a program mode and illuminate steady in a view mode.

Abstract: A circuit and method of protecting the antiparallel diodes of a power bridge circuit from stress induced failures caused by the fast operation of the power switches. An auxiliary power switch is provided in parallel to the main power switch which is operable during the reverse recovery of the antiparallel diode, after which the main power switch carries the bulk of the switch current.

Abstract: A system for generating a time overcurrent curve from a set of time and current inputs. The overcurrent curve is generated by simultaneously finding four coefficients of a standard overcurrent equation. Two of the coefficients are found by successive approximation and two of the coefficients are found via a least squares fit approximation. After the coefficients are found, they are used in the standard overcurrent equation to produce a set of data points indicative of the overcurrent curve. The data points are transferred to an overcurrent relay for the detection of overcurrent conditions.

Abstract: A fault protection arrangement for protecting power conversion circuits, for example switch mode power supplies and the like, from overcurrent and short circuit faults. The fault protection arrangement includes multiple fault protection features, for example soft-start delay, fault delay and automatic reset, with the timing of each of these three features capable of being set independently of the other two while minimizing integrated circuit (IC) pin count and also minimizing the number of external components required for programming the timing of these features. The fault protection circuit may be used to advantage with any power conversion regulator topology.

Abstract: An arc fault detector embodied as both a stand alone device and in combination with a circuit interrupting device such as a ground fault circuit interrupter (GFCI) functions to provide protection from potentially dangerous arc fault conditions. The device utilizes line side and load side pickup coils to permit distinguishing between arc faults occurring on the line side and the load side of the device. The arc fault circuit interrupter (AFCI) circuitry portion of the device shares components from the GFCI circuitry portion as an integral part of its functionality. The AFCI utilizes the electromechanical power carrying, portion of the GFCI, including the AC line disconnect circuitry, the power supply and the physical housing. In addition, the AFCI employs quantitative detection using variable gain control in combination with either a load disconnect or audible/visual alarm indication.

Abstract: A voltage regulator circuit includes a circuit input and a circuit output for coupling to a load. A circuit interrupt element is coupled between the input and the load for breaking the circuit between the input and the load. A sensing circuit coupled to the output senses when a signal applied to the load exceeds a defined limit. A trigger circuit coupled to the sensing circuit causes the circuit interrupt element to trip when the sensing circuit senses a signal which exceeds the defined limit.

Abstract: A circuit breaker includes separable contacts for movement between a closed position and an open position. An operating mechanism moves the separable contacts between the closed and open positions and has a closed state and an open or tripped state which corresponds to the open position. A trip circuit senses electrical current flowing through the separable contacts, employs the sensed current to trip the operating mechanism to the tripped state to move the separable contacts to the open position, and provides plural status signals. A display circuit cooperates with the trip circuit and includes light emitting diodes for outputting the status signals. A battery powers the display circuit which further includes an oscillator circuit for modulating the LEDs to reduce power from the battery to the display circuit.

Abstract: An abnormality detection and protection circuit is provided in association with a driving circuit for a semiconductor device, for detecting plural types of abnormalities and protecting the device from the abnormalities. The present circuit includes a plurality of abnormality detecting devices for detecting the plural types of abnormalities, respectively, a plurality of abnormality storage circuits each provided for the corresponding abnormality detecting devices for storing occurrence of the corresponding type of abnormality, and an abnormality transmitting circuit that transmits a signal representing the detected type of the abnormality to an overall control system for controlling a plurality of semiconductor devices.

Abstract: A circuit breaker interconnect arrangement and a method for selective interruption of electrical circuits includes at least one upstream circuit breaker having an upstream electronic trip unit and a microprocessor and a plurality of downstream circuit breakers connected to the upstream circuit breaker. The microprocessor transmits a trip command signal to the downstream electronic trip units at the occurrence of a predetermined load condition, such as an overload condition, through the upstream circuit. One or more downstream circuit breakers are tripped after the predetermined time delay for tripping according to a predetermined priority until the load condition through the upstream circuit is reduced below the predetermined load condition whereby the upstream circuit breaker is deterred from interrupting current in the upstream circuit.

Abstract: An arc fault detector of the type which generates a trip signal when a time attenuated accumulation of pulses produced each time an arc is struck reaches a selected value, includes a pulse conditioner which discriminates against false trips induced by phenomena such as tungsten bulb burn out and turn on of a cold tungsten bulb controlled by a dimmer. The pulse conditioner includes a zener diode which limits the amplitude of the pulses applied to the integrator, and stretches all of the pulses to reduce the variation in pulse duration. The latter can be accomplished by a peak detector which stretches pulses which reach the zener limit to a duration of at least about a half cycle.

Abstract: In an input protection circuit, a bipolar protection device is constituted of a semiconductor substrate of a first conductivity type, a first diffused layer of a second conductivity type formed in the substrate and connected to an input signal pad, a second diffused layer of the second conductivity type formed in the substrate to extend in parallel to the first diffused layer but separately from the first diffused layer by a first space, and a third diffused layer of a high impurity concentration and of the first conductivity type formed in the first space in the substrate to extend in parallel to the first and second diffused layers, in junction with the second diffused layer but separately from the first diffused layer. When a backward biasing voltage is applied, the thickness of a depletion layer formed is made large, so that generation of hot carriers is minimized.

Abstract: Converters having a 1st power converter (1) on the mains systems side and a 2nd power converter (9) on the load side may have valve arms with insulated gate bipolar transistors (IGBTs) (T1, T2; T1', T2'). In order to be able to switch high currents, as are required in traction applications, a plurality of IGBTs (T1, T2) and (T1', T2') are operated electrically in parallel with one another. In order to avoid destruction or explosion of a module having IGBTs (T1, T2; T1', T2') of this type in the event of a short circuit, a fuse (Si1, Si2; Si1', Si2') is connected in series with each IGBT (T1, T2; T1', T2') on the cathode side thereof, which fuse blows when a predeterminable limit current intensity is exceeded, and thereby interrupts the short-circuit current. The current then flows only via the parallel-connected IGBT.

Abstract: Power supplied from a battery via a power-supply line is distributed via switching means to load drive lines, connected to loads, respectively. Memory means stores the data of current-breaking time characteristics providing the breaking time which corresponds to the amount of each excessive current and the capacity of each load. When any of the current detection means has detected an excessive current flowing through any of the load drive lines, control means breaks power supplied via the load drive line to the load, by opening the switching means immediately after the corresponding breaking time has elapsed.

Abstract: The trip device with an electronic processing unit which gives a tripping order in terms of the rms value of the current measured by current transformers and of the threshold and time delay setpoints. The non-linearity of response of the current transformers is corrected by a device which modifies the current, threshold, or time delay values. These corrected values enable precise trippings to be achieved in compliance with the values of the current flowing in the circuit breaker. The type of correction is adapted to the circuit breaker rating by parameters obtained by tests and previously stored in a device.

Abstract: Arcing-faults in an electric power distribution system are detected by a circuit which includes a band-pass filter generating a low frequency bandwidth limited arcing current signal having a bandwidth above the measurable harmonics of the ac current but below the frequency band of power line communications systems, about 3 KHz to 20 KHz and preferably about 6 KHz to 12 KHz. For each cycle of the ac current that this low frequency bandwidth limited arcing current exceeds a threshold, preferably related to the amplitude of the ac current, for a selected duration of the cycle, a fixed pulse is generated. If a time attenuated accumulation of these fixed pulses reaches a selected level representative of a number of closely spaced cycles in which the arcing current has been detected for the selected duration, an arc indicative signal is output.

Abstract: An overcurrent and short circuit protection device for a power semiconductor component is responsive to output current signals representing the actual output current(s) of the semiconductor component. A short-circuit window comparator receives the output current signals and produces an error signal when the sum of all output current signals is less than a minimum allowable value or more than a maximum allowable value. An overcurrent window comparator receives the same output current signals, determines a positive maximum instantaneous value and a negative maximum instantaneous value, and produces an error signal when either one of these exceeds a maximum allowable value. An error signal from either window comparator interrupts operation of the power semiconductor component and locks out all higher level control signals to the power semiconductor component.

Abstract: An overcurrent trip device includes a capacitor 13 that stores power for driving a trip electromagnet 7, and a charging current generating means 18 that starts charging the capacitor 13 upon detection of an overcurrent and that completes the charging of the capacitor 13 until a trip control circuit 5 outputs a trip signal. The operation of the trip electromagnet 7, which is driven with the charges of the capacitor 13 by causing a thyristor 12 to be turned on by the trip signal, is continued until the charges of the capacitor 13 are lost, and even after the power supply from a rectifying circuit 4 is stopped due to the opening of a circuit breaker 8, it is made impossible to reset and re-close the circuit breaker 8 for a predetermined time.

Abstract: A self-powered multiple phase circuit protection device including a plurality of current transformers connected in parallel with each other and associated with one phase of a multiple phase load for providing signals representative of the current flowing in an associated phase. A switch can be actuated to interrupt power to the multiple phase load, and a fault determining circuit is connected to the circuit transformers and to the switch for actuating the switch during at least one predetermined condition of the current signals. The fault determining circuit has digital pulse extender circuitry for converting the current signals into DC signals, and a digital timer for delaying actuation of the switch.