Abstract: A sputtering arc fault detector (10) for a system having an electrical conductor (14) carrying current to a load. The sputtering arc fault detector includes a current monitor (64) coupled to the conductor for generating a variable signal responsive to behavior of the current in the conductor. A level detector (58) is coupled to the monitor and generates a first pulse when the variable signal exceeds a first level. A step detector (62) is coupled to the monitor and is responsive to rapid step increases of the variable signal. The step detector generates a second pulse when the variable signal exceeds a second level. An arc verifier (48), which is coupled to the level detector and the step detector, combines the first and second pulses, and generates a fault signal when the combined pulses exceed a third level.

Abstract: A self-powered current monitor for monitoring current in electric power systems. Various data relating to input currents may be displayed, such as current magnitude, current demand, and harmonics levels. Operating power is derived from one or more of the input currents. The power supply configuration may include a burden-reducing means to reduce the burden on input current sources during sampling of the input currents. The self-powered current monitor (1) includes a power supply section (3), input resistors (R1 and R3), an analog-to-digital converter circuit (5), a microprocessor circuit (6), a memory circuit (9), and a display circuit (7). Optional features include a burden-reducing circuit (2), input circuit protective elements (D1, D2, D3, D4, R2, and R4), an amplifier circuit (4), a user interface circuit (10), and an interface circuit (8) for communication to other equipment.

Abstract: A voltage overshoot protection circuit includes an integration circuit configuration. The integration circuit configuration is included in the voltage overshoot protection circuit so as to integrate excess diverted current drawn from a bus. The voltage overshoot protection circuit is adapted to be electrically coupled to the bus.

Abstract: A device and method for protecting a CPU from being damaged by overrating voltage or overrating current. The means for protecting the CPU is to detect the working voltage and working current provided to the CPU, to compare the working voltage and working current with the voltage and current settings, and to determine whether overrating voltage or/and overrating current is generated. If overrating voltage or/and overrating current occurs, a control signal is sent to the soft switch of an ATX power supply, a first switch, or a second switch in the device in order to cut the supplying route of the power supply. Therefore, the CPU is not broken down due to overrating voltage or/and overrating current. Detection means for detecting the breakdown of a switch-type stabilizing controller of the power supply to the CPU are also provided.

Abstract: An overcurrent prevention circuit which removes noise upon transmission of a signal over a signal line between two devices for which different power supplies are used and prevents overcurrent from flowing through the signal line to prevent an otherwise possible breakdown of the devices or an associated element. Current from a waveform outputting terminal to an external signal line is detected from a voltage drop across a resistance part. Then, in response to a result of the detection, an N-channel D-type MOS transistor which supplies current of an output signal to the waveform outputting terminal is controlled between on and off to interrupt supply of power. Consequently, no overcurrent flows out from the waveform outputting terminal, and a clamp diode for removing noise connected to the waveform outputting terminal does not suffer from a breakdown by overcurrent.

Abstract: An AC transfer switch is provided for switching between a first line cord and a second line cord. The AC transfer switch is designed to be fault tolerant and ensures that continuous operating power is supplied to a load during the transfer process. The system includes a first input from a first power line cord, a second input from a second power line cord, a switch for switching an output between the first and second power line cord, wherein the switch further includes a first contactor set for selecting the first line cord and a second contactor set for selecting the second line cord, the first and second contactor sets including two contactors in series and a control circuit for controlling the switch to select between the first and second power line cords.

Abstract: An arrangement for transmitting electric power from a source point to a load point comprises (i) a first sensor to monitor the amount of power being supplied from the source point, (ii) a second sensor to monitor the amount of power being received by the load point, and (iii) communication circuit for communicating to a control circuit information in respect to the amount of power supplied from the source point as well as that received by the load point. The control circuit then compares the amount of power supplied versus that received, and provides a warning and/or halts the supply of power in case a substantive discrepancy were to occur between power supplied versus power received. Thus, in case an improper loading were to occur between the source point and the load point, it would be detected by the control circuit, which would then instigate protective action.

Abstract: In a power distribution system, a reliable, accurate, and energy efficient fault circuit indicator is provided through a microcomputer-based fault current indicator design. First, reliability is improved inherently because the microcomputer, and the software embedded therein, replace the functionality of numerous discrete, less reliable electronic components found in prior designs. Second, the embedded software is capable of placing the fault current indicator in one of a number of energy conservation states, without compromising the fault current indicator's ability to provide information relating to the occurrence of a fault. Finally, greater fault current indication accuracy is achieved by detecting excessive line current, followed by a significant drop in line voltage.

Abstract: The protective relay is primarily energized by a voltage transformer tap on the power circuit. The current transformers that provide the monitoring current to the protective relay also provide an auxiliary power input to the power supply circuit. A switching circuit monitors the input voltage and switches to the current feed to generate the relay supply voltage when the input voltage drops below a predetermined level. In one embodiment the fault tolerant power supply is provided as an optional, modular, add on unit. In a second embodiment, the power supply is an integral part of the protective relay where the current shares a common input between the monitoring and power circuit and the voltage input is common to both the power supply and any metering circuits contained within the protective relay.

Abstract: The invention concerns a process for detecting a ground fault in an electric power transmission line with three phase conductors where, upon response of the protective device, a fault identification signal indicating a single-pole or multipole fault is generated by comparing currents and voltages with predefined limit values. To reliably distinguish not only between a single-pole and a multipole ground fault, but also to reliably determine the phase conductor affected by the ground fault in such a process, measured quantities, corresponding to the currents of the zero phase-sequence system and the negative phase-sequence system, are formed when no fault identification signal is present. In the event of a ground fault of one phase conductor, when the phase angle between the two measured quantities drops below a predefined limit phase angle, an auxiliary signal is generated. Another auxiliary signal is generated when the currents in the two other phase conductors drop below a fraction of the ground current.

Abstract: A battery control system for an electric vehicle 1 which includes a propelling motor (7) and an electric power unit(10)for driving the motor comprises a plurality of discrete batteries (13a) to (13d) connected in series and outputting a predetermined motor voltage, a plurality of selection switches (25a) to (25h) which are provided corresponding in number to the discrete batteries(13a)to (13d) and selectively connect one of the discrete batteries (13a) to (13d) in parallel to a control circuit (16), a judging device (23) which determines a state of electric energy possessed by each of the discrete batteries (13a) to (13d) and a control device (23) which selects one of the discrete batteries(13a) to (13h) having a maximum energy based on the state of electric energy as determined by the judging device and activates one of the corresponding selection switches (25a) to (25h) accordingly, and a control stabilization circuit (24) provided between the selection switches (25a) to (25h) and the control circuit (16) t

Abstract: A device and method for protecting a CPU from being broken down by overrating voltage or overrating current. The means for protecting the CPU are to detect the working voltage and working current provided to the CPU, to compare the working voltage and working current with the voltage and current settings, and to determine whether overrating voltage or/and overrating current is generated. If overrating voltage or/and overrating current occurs, a control signal is sent to the soft switch of an ATX power supply, a first switch, or a second switch in the device in order to cut the supplying route of the power supply. Therefore, the CPU is not broken down due to overrating voltage or/and overrating current. Detection means for detecting the breakdown of a switch-type stabilizing controller of the power supply to the CPU is also provided.

Abstract: A circuitry for detecting a fault current or leakage current on the supply line of an electronic circuit includes a current source which is rated for a maximum allowed fault current or leakage current. The current source is fed by an auxiliary voltage source. The potential on the supply line which prevails when the supply voltage is disconnected due to the leakage current is determined and assessed by a potential monitor.

Abstract: A indicating power cord system including a housing and an elongated extension cord having a first end connected to the housing and a second end having a plug coupled thereto for being releasably inserted in a standard electrical receptacle to receive power therefrom. Next provided is an electrical outlet positioned on the housing for being electrically connected to a block heater of a vehicle. The electrical outlet is electrically connected to the extension cord with a relay contact and associated relay coil connected therebetween. The relay contact has a closed unbiased orientation upon the lack of receipt of current by the relay coil and an open biased orientation upon the receipt of current by the relay coil. Also included is a thermistor positioned on the heater block of the vehicle. The thermistor can be connected to the relay coil for providing current thereto upon the engine block reaching a predetermined temperature.

Abstract: This invention provides an electronic safety break device and method for protecting an electrical circuit. In a preferred embodiment, the electronic safety break device of this invention includes switching means for making and breaking an electrical connection, current measuring means for measuring the magnitude and direction of the current flowing through the connection, voltage measuring means for measuring voltage on each side of the electrical connection, and means responsive to the current and voltage measuring means for controlling the switching means. The electronic safety break device and method of the present invention thus provide for a bidirectional safety break for an electrical connection between a rechargeable battery and a load and other external circuitry, protecting the battery from excessive charge and discharge currents and from undervoltage and overvoltage conditions, or any combination of these conditions.

Abstract: A power supply switching apparatus for electronic equipment including a first control circuit connected to a battery. The first control circuit monitors a power supply voltage of the battery to output a first control signal when the power supply voltage of the battery is lower than a first predetermined voltage. The first control circuit also outputs a second control signal when the power supply voltage of the battery is higher than a second predetermined voltage. A second control circuit monitors whether power is supplied from an external power supply to the electronic equipment, to generate a third control signal when the power is not supplied from the external power supply. The second control circuit generates the third control signal regardless of whether the second control signal is present, when power is supllied from the external power supply. A switching circiut section supplies power from the battery to the internal circuit when the first and third control signals are not present.

Abstract: The positive sequence voltage on the power line is measured at a given time, i.e. the present time, and also for one cycle earlier, and the ratio thereof is then compared against a threshold value of 0.9. There are four other supervisory tests which also must be true for a loss of potential condition to be indicated. These include determination of change in positive sequence current and angle and zero sequence current and angle. If the change in those values is smaller than selected thresholds, then a loss of potential condition is indicated.

Abstract: A trip indicator for a circuit breaker in an electrical distribution system. The trip indicator provides a visual indication of the activation of a trip signal caused by arcing fault detector (AFD) or ground fault interrupter (GFI) circuitry. The trip indicator comprises one or more light sources, one or more plungers having a colored tip or one or more bimetal disk having a colored top. In response to activation of a trip signal by the AFD or GFI circuitry, the light source(s) illuminate, the plunger(s) move from a retracted position to an extended position and the bimetal disk(s) move from a generally flat position to a convex position. A conduit is provided within the housing of the protective device for conveying light or the reflection of light between the light source(s), plunger(s) or bimetal disk(s) and an opening of the housing.

Abstract: Both fault location and fault resistance of a fault are calculated by the present method and system. The method and system takes into account the effects of fault resistance and load flow, thereby calculating fault resistance by taking into consideration the current flowing through the distribution network as well as the effect of fault impedance. A direct method calculates fault location and fault resistance directly while an iterative fashion method utilizes simpler calculations in an iterative fashion which first assumes that the phase angle of the current distribution factor D.sub.s is zero, calculates an estimate of fault location utilizing this assumption, and then iteratively calculates a new value of the phase angle .beta..sub.s of the current distribution factor D.sub.s and fault location m until a sufficiently accurate determination of fault location is ascertained. Fault resistance is then calculated based upon the calculated fault location.

Abstract: A lighting circuit for a discharge lamp comprises detection means for detecting a voltage and/or a current to be applied to a discharge lamp or a voltage and/or a current equivalent thereto, input voltage/current detection means for detecting an input voltage and/or an input current to the lighting circuit, and abnormality detection means for stopping power supply to the discharge lamp when detecting an abnormality in the discharge lamp or a circuit abnormality based on those detection signals. In the abnormality detection means, a plurality of reference values for comparison or a plurality of reference ranges are set for the detection signals, and determination times are set in association with the reference values or reference ranges.

Abstract: An integrated protection system for an electrical distribution system including a panelboard for receiving power from a utility source and distributing the power to a plurality of branch circuits each having line and neutral conductors for delivering the power to a load. The integrated protection system comprises a plurality of arcing fault detectors and line interrupters attached to positions in the panelboard. The arcing fault detectors detect the occurrence of an arcing fault in either of the branch circuits, while the line interrupters disconnect the load from the power source in response to the detection of an arcing fault in either of the branch circuits. The line interrupters and arcing fault detectors may comprise separate modules, each being connected to one of the positions in panelboard or being attached externally to the other module.

Abstract: A switching mode power supply which controls power source supplied to electronic equipment, which is designed to protect a circuit against an overvoltage through a power line of coil or overcurrent on the occurrence of short-circuit of power line. The switching mode power supply of the present invention comprises a switching transformer for receiving DC voltage to a primary coil from a rectifier, and inducing respective different predetermined voltages into a plurality of coils on the secondary and third side of respective different turns ratio, an error detection and feedback for inputting the voltage V.sub.

Abstract: The protection device of an electronic circuit is an electronic AC circuit protection device. The protection device has the characteristic of over-voltage protection, over-current protection, electronic switch, and soft start. Devices of the protection circuit are electronic box, electronic devices box, and power factor regulator that is designed in the structure of L.C. in parallel on the source side of the protection circuit. The protection circuit can be applied in switching power supply, electronic ballast, etc., electronic circuit devices. The main electrical electronic devices include Triac Thyristor, Silicon Controlled Rectifier, Phototriac Coupler and Photothyistor Coupler etc. The protection device has characteristic of standing surge current that solving the problem of life and reliability of electronic devices in now a day. The invention is a necessary protection device for electrical industrial.

Abstract: Negative sequence, positive sequence and zero sequence quantities are determined from voltage and current values for a power signal on a radial distribution feeder line. Negative sequence quantities are evaluated against selected threshold standards; the negative sequence impedance is also determined, which is then evaluated to determine fault direction (if a fault is indicated). If a reverse fault is declared, the trip output of overcurrent elements in the protective relay for the feeder is blocked for a selected period of time. The same evaluation process is carried out for zero sequence quantities. A selection process determines whether the negative sequence or the zero sequence element is to be enabled. Further, voltages and currents of all three phases of the power signal are evaluated to determine relative change over a period of one cycle. If within the one cycle there is a decrease of both voltage and current in all three phases of approximately 10%, the overcurrent elements are also blocked.

Abstract: A digital decaying current offset correction method and apparatus, in one aspect, separates the requirements of detecting fault existence from the requirements of detecting fault location. Once the decaying offset removal routine is initiated, current and voltage are sampled and, for each current and voltage sample, current and voltage phasors are generated. The current phasor values, which are not offset corrected, may be used to determine whether to trip a breaker. Once the breaker is tripped, the decaying offsets are removed from the current phasors. The offset corrected current phasors are then used to locate the fault.

Abstract: Gate leakage in the DMOS transistor of a low-side driver device is detected and reported by utilizing a sense circuit to sense the voltage on the gate of the DMOS transistor, and by determining whether the voltage on the gate of the DMOS transistor has exceeded a predetermined value within a predefined period of time when the device is turned on.

Abstract: A method and apparatus for receiving, monitoring and characterizing network power information in real time through the use of a specialized display system. A processor receives three phase current and voltage information from a network power relay, converts and scales that data into a two-dimensional vector having coordinates that are represented by, and displayed as, a single pixel on a display screen. The repeated monitoring provides a Feature Map (FM) of the network system that can be easily read and understood by operating personnel.

Abstract: A coaxial drop cable safety device is used for cable television, data and telephony applications. The device is used on buried drop cable where 60 Hz powering voltages applied to the drop cable exceed low voltage safety limits and where the drop cable is buried at depths which is less than the minimum required to meet electrical safety codes. Tap end and premise end units are connected to the drop cable. The tap end unit applies a DC voltage to the center conductor of the drop cable. A monitoring circuit in the tap end unit monitors the center conductor DC voltage to a fault from the center conductor to ground along the drop cable. The tap unit will immediately remove the powering voltage In the event of either an open or faulted condition on the center conductor along the entire length of the drop cable.

Abstract: At least two different time constants are used to produce the polarizing memory reference voltage which in turn is used in a protective relay for power transmission lines. For most conditions, a relative short time constant of 1.75 cycles is used, while under other specific conditions, determined automatically, a longer time constant of 15.75 cycles is used.

Abstract: A circuit to discriminate the source of harmonic distortion of the output voltage comprises voltage sensors coupled to the output terminals of a source of electric power and to a point of regulation remote from the source for sensing the output voltage waveform present at each of these locations. The circuit then utilizes these two sensed waveforms to discriminate the source of any harmonic distortion between the source of electric power and the utlization equipment. This circuit calculates the percentage total harmonic content of each of the sensed waveforms, and compares them to determine the source of distortion. If the percentage total harmonic content sensed at the point of regulation is greater than that sensed at the terminals of the source of electric power, the source of distortion is discriminated to be the utilization equipment; otherwise, the source of distortion is identified to be the source of electric power.

Abstract: A failure detection system detects a failure in a by-pass switch of a power converter. The by-pass switch switches the electric power supply so that electric power is supplied from a standby power source to a load instead of from a power converter. A switch operation circuit turns the by-pass switch on and off. A first current detector detects the inverted output current of the power converter. A second current detector detects the load current flowing through the load. An operational amplifier adds the outputs of the first and second current detectors. A comparator detects a failure of the by-pass switch. If the addition result given by the operational amplifier is outside a predetermined range of values when the switch operation circuit is turned off, the comparator concludes that the by-pass switch has a failure.

Abstract: A stabilized power source circuit is provided with an over current protecting circuit which obtains either a current value or a voltage value corresponding to an output current value of an output transistor as a detected value, compares the detected value with a predetermined constant value and lowers the output current when the detected value exceeds the predetermined constant value. A comparing value generating circuit receives an external signal, generates one of either a predetermined plurality of voltage values or a predetermined plurality of current values in response to the level of the received external signal and transmits the same to the over current protecting circuit as the predetermined constant value.

Abstract: A method of protecting an adjustable impedance element such as a transistor controlling the power supplied to an electric motor, in particular in a motor vehicle, wherein the control of said adjustable impedance element is modified when the current passing through it exceeds a given threshold, characterized in that said current threshold is an increasing function of the voltage U.sub.M across the terminals of the motor.

Abstract: An electronic relay having a current sensor device (C1, C2, C3), logic inputs (3) and an electronic circuit (4) provided with processing means capable of calculating, from the current signal (I) supplied by the current sensor device and a rectified voltage signal (V) supplied by one of the logic inputs, the value of the power factor of the motor (cos.phi.) and/or the value of the power supply voltage (U) of the motor.

Abstract: A circuit for protecting from overload currents includes an electronic power device having at least first and second terminals and at least one control terminal. The circuit also includes at least one voltage-generating circuit for generating a reference voltage having a predetermined pattern. The voltage-generating circuit includes at least a first terminal connected to the first terminal of the power device and at least a second terminal coupled to the second terminal of the power device through a sensor. The circuit also preferably includes at least one comparator for comparing the reference voltage with a voltage present across the sensor. The comparator has at least one output terminal and at least first and second input terminals. The first and second input terminals are respectively connected to a third terminal of the voltage-generating circuit and the second terminal of the power device.

Abstract: A residual current safety switch has a residual current transformer (3) connected to an evaluation circuit (5) that controls an electromagnetic trigger device (K1) for actuating switching contacts (1, 2). An overvoltage protection circuit (V1), for example designed as a voltage-dependent resistor, is provided. The evaluation circuit (5) and/or the overvoltage protection circuit (V1) are/is connected to terminals that supply them with voltage when the switching contacts (1, 2) are closed through lines (7, 8), with one of the lines extending through the residual current transformer (3) and the other not. The supply current of the electronic components and/or the current that flows through the overvoltage protection circuit (V1) is lower than the triggering current when the nominal voltage is applied.

Abstract: Power transistors, especially MOSFETs and IGBTs, must be protected adequately in the ON state against a short circuit in the load circuit, in order to avoid their destruction. Until now, the power transistor was turned off if a short-circuit current appeared by providing that its gate-to-source path, in the event of a short circuit, was short-circuited through another transistor, and the power transistor was thus turned off. However, if that readjustment of the current took place too fast, the power transistor was able to be damaged by overvoltage. That is counteracted by a voltage sensor configuration, which detects the voltage change in the load path of the power transistor and reduces the potential at the control terminal connection of the other transistor if the output voltage rises.

Abstract: This invention provides a small-sized magnetic amplifier with a simple construction.

Abstract: An electrical strike sensing system for providing an alarm if the underground boring equipment encounters a potentially hazardous condition. The system senses current carried through the equipment, as well as the voltage between the equipment and a reference. The measured current is converted to a percentage of a reference current, and the voltage is converted to a percentage of a reference voltage. The current and voltage percentages are added, and if the sum exceeds 100%, the alarms are activated. The current and voltage percentages, as well as the date and time of the strike, are stored in a nonvolatile memory.

Abstract: A transistor protection circuit of a monitor for protecting a transistor from a high voltage liable to instantaneously occur during a power on/off or mode conversion includes a driving transformer for generating a high voltage driving signal according to a horizontal oscillating signal, a transistor which switches according the high voltage driving signal received into a base thereof and having an emitter being grounded, a flyback transformer connected to a collector of the transistor for generating a high voltage, and a high voltage cutoff unit connected between the base and collector of the transistor. Thus, the high voltage of the flyback transformer supplied to the collector of the transistor is bypassed to the high voltage cutoff unit when an abnormal high voltage instantaneously occurs to thereby protect the transistor.

Abstract: A telephone having a semiconductor line switch TR1 is protected from excess line voltage or current by the use of current foldback techniques. A current sensing resistor R6, in series with the line switch provides a measure of the line current and this operates a bypass transistor TR4 which reduces the drive current for the line switch TR1 causing it to come out of saturation and begin to block line current. A voltage sensing resistor R7 provides a measure of the voltage across TR1 and this further increases the bypass current through TR4. This ensures that the voltage and current applied to TR1 remain within permitted limits.

Abstract: An electric vehicle control system which maintains good driving performance under normal conditions, and can cut off driving current upon malfunction of a microcomputer before restarting. A setting circuit of a comparing and operating circuit has a set signal fixed to V2 if an accelerator pedal is released. If a microcomputer malfunctions to drive an inverter absent a depression of the accelerator pedal, a current flows from a battery and a battery current sensor generates an output signal n. If this value exceeds V2, a comparator is turned on, which also turns on a transistor to energize a relay and disconnects an inverter drive signal s to break the power supply from an inverter to the ac motor. Upon disconnection, an alarm lamp is lit to issue an alarm to the driver. The disconnection is held by a delay circuit until the power is reset.

Abstract: A circuit interrupter samples waveforms in a protected circuit by taking samples in pairs spaced 90 electrical degrees apart. The sum of the squares of samples in each pair, which is representative of the RMS value of the fundamental frequency of the waveform, is used for instantaneous protection by comparing a running sum of the squares for the two most recent pairs of samples to a threshold representative of the instantaneous trip pick-up value. This sum of the squares of successive two pairs of samples is also used for short delay protection. A delay between successive pairs of samples is varied to produce a selected equivalent sampling rate after a given number of samples. Samples accumulated at this equivalent sampling rate, which is sixty-four samples per cycle in the preferred embodiment, are used for long delay protection and metering.

Abstract: A semiconductor power module which provides reliable overvoltage protection including an overvoltage protection device which functions so that when an overcurrent flows to an IGBT (1), a sink transistor (10) turns on and the IGBT (1) turns off accordingly. As the IGBT (1) turns off to cut off the overcurrent, a high surge voltage is applied to the IGBT (1). At this time, however, a clamp current flows trough a clamping circuit including a Zener diode (6), a diode (7) and a resistance (8) and part of it is divided to a transistor (Q11), so that a transistor (Q12) turns on and the sink transistor (10) turns off as the result. Accordingly, the clamp current increases a gate voltage of the IGBT (1). Hence, large part of the load current flows in the IGBT (1), and only a little flows to the clamping circuit. Accordingly, overheat of and damage by burning to the clamping circuit will not be caused even if both the overcurrent and overvoltage are applied.

Abstract: To prevent unnecessary power outages, and to remove feeder lines from service only when certain hazardous fault conditions occur, a load analysis system including an apparatus and method, monitors the load level of a feeder line and determines the presence of any arcing on the feeder line. In a two stage load pattern analysis, the presence of arcing and load current level changes are used to discriminate high impedance, low current conditions including a downed conductor, a broken and dangling conductor, a tree or object contact with the feeder line, overcurrent activities, and normal switching events such as recloser operation. The load analysis system also provides output commands including wait, alarm, trip-ready, trip and normal, depending upon which status is diagnosed.

Abstract: A driving circuit for driving a given load based on a load control signal is provided which includes a power transistor, a protective circuit, and a power transistor control circuit. The power transistor is responsive to the load control signal inputted to the driving circuit to be turned on for activating the load. The protective circuit is arranged to be activated by the load control signal to monitor a malfunction of the power transistor caused by overheating or overcurrent flow to restrict an operation of the power transistor. The power transistor control circuit is arranged to prohibit the power transistor from being turned on until the load control signal reaches a preselected level required for operating the protective circuit stably.

Abstract: In an electric circuit supplying AC line current to a load (30, 31) from an AC source (26) of given frequency providing repetitive cycles, arc detection is provided by sensing cycle to cycle changes in the AC line current. The AC line current is sampled with a harmonic notch filter (72) at a plurality of n phases .THETA..sub.1 through .THETA..sub.n during each of a plurality of m cycles of the AC source (26), to provide a plurality of currents I.sub.n,m, where n is the phase and m is the cycle. The differences (I.sub.n,m)-(I.sub.n,m-x), where x is a designated number of cycles, provide a plurality of current difference signals. The absolute values of these current difference signals ID are accumulated in a synchronous summer (94) over the m cycles. An arc indicative signal is generated in response to given conditions and given combinations of conditions (116) of the cumulative absolute current difference signals ID.

Abstract: A poly-phase no-break power transfer phase balance synchronization sense circuit for an electric power generation and distribution system having a present source of electric power supplying poly-phase AC electric power through a first contactor to utilization equipment and a target source of electric power connectable to supply poly-phase AC electric power to the utilization equipment through a second contactor, a transfer of the source of AC electric power from the present source to the target source being accomplished by closing the second contactor prior to opening the first contactor upon synchronization of the two sources, comprises a circuit for rectifying the poly-phase AC electric power generated by the present source, the circuit generating a first rectified output signal, a circuit for rectifying the poly-phase AC electric power generated by the target source, the circuit generating a second rectified output signal, and a circuit for differentially summing the first rectified output signal and the s

Abstract: An electronic circuit breaker includes multiloop control loops based upon a current sensing loop and a voltage sensing loop. The current sensing loop also operates to drive a timer which ultimately controls whether current flows through the load or not. Additionally, the current loop is made to be dominant over the voltage loop. However, during normal operation the voltage loop and current loop act cooperatively to effectively control the impedance as seen by the load.

Abstract: A power supply apparatus having an AC-DC converter includes a transformer, an AC-DC converter, a power supply controller, a push switch, and a relay and a relay contact. The relay is connected to an AC power supply voltage input side of the primary coil of the transformer, turned on to apply the AC power supply voltage to the primary coil of the transformer when the push switch designates to start applying the DC power supply voltage to the load, and turned off to stop applying the AC power supply voltage to the primary coil of the transformer when the push switch designates to stop applying the DC power supply voltage to the load.