Abstract: A control circuit is provided for a circuit interrupter that achieves an inverse-time characteristic for overcurrents that include instantaneous current levels higher than the interrupting capability of the circuit interrupter by synchronizing the operation of the circuit interrupter to ensure that circuit interruption takes place when the instantaneous current is within the interrupting capability of the circuit interrupter. This interrupting capability is similar to let-through current and is defined by the instantaneous magnitude of the current at the time of interruption or at a particular stage thereof. The control circuit is responsive to a time-current characteristic signal generator that provides a time-current signal in response to overcurrent after the passage of a time delay that is inversely related to the overcurrent.

Abstract: A circuit breaker with over-temperature protector and low error I.sup.2 t calculator is provided. The over-temperature protector includes a fixed current source which provides current to a resistive element to produce a voltage which thereacross which increases with a positive temperature coefficient as the surrounding temperature increases. The resistor is connected to the base-to-emitter circuit of a transistor. The base-to-emitter circuit has a minimum firing voltage which decreases with an increase in ambient temperature. The value of the resistive element, the amount of current provided by the fixed current source and the transistor base-to-emitter minimum firing voltage are chosen to cause a circuit breaker to be actuated. There is also provided an active memory device which is utilized to discharge a capacitor with a time constant which approximates the heat dissipating time constant associated with a conductor to be protected by the circuit breaker in question.

Abstract: A differential current protection circuit breaker that operates as a magnetic amplifier has a secondary winding connected in series to a complex, predominately capacitive measuring impedance and a square wave generator. An evaluating circuit is connected at a tap and is actuated along a tripping device and a switch latch of a switching contact device. The evaluation circuit is blocked by a sensor that responds to extraneous current surges or voltage surges during a predetermined response time. A blocking device in the tripping device responds to the signals from the sensor.

Abstract: An electronic relay control circuit is provided for liquid cooled electric power transformers. The control circuit senses the rate of change of internal tank pressure and operates its relays in response to a sudden pressure increase. Relay control connections are provided for operating transformer trip and annunciator circuits. The relay response is field adjustable.

Abstract: A method and apparatus are disclosed for detecting excessive current draw in an electrical load particularly of the type having an in-rush current when first energized. The electrical load is connectable to an energy source through a current sensing circuit and an actuatable switch. The current sensing circuit provides a load sense signal that varies in response to current draw by the load. A control signal is provided to actuate the switch. A coupling network temporarily couples the control signal to the load sense signal to offset the change in the load sense signal resulting from current in-rush. The load sense signal is compared against a reference signal. The comparator outputs a signal indicative of whether the load sense signal is greater or less than the reference signal. One signal from the comparator is indicative of excessive current draw.

Abstract: A fault current circuit breaker for monitoring electrical circuits having a total current converter with a primary circuit including supply and return leads which are to be monitored and a secondary winding acting upon an electronic limiting value circuit which controls an electromagnetic retaining device. Switch contacts are provided for switching the circuit to be monitored when a predetermined fault current is exceeded. In order to enable self-monitoring, a current is briefly and periodically fed into an additional winding of the total current converter, with the current simulating a fault current, and a pulse voltage which appears at the output of the electronic limit value circuit due to the current in the additional winding is fed to an evaluation circuit, which causes the switch contacts to open in the absence of periodic pulses coming through the electromagnetic retaining device.

Abstract: A protection device (14) for an integrated circuit (12) created on a semiconductor body (24 and 26) utilizes one or more semiconductor diodes (D.sub.L and/or D.sub.H) that have subsurface PN junctions (46 and/or 56) for preventing high-magnitude voltages, such as those generated by electrostatic discharge, from damaging sensitive electronic elements of a protected circuit component (16) formed from part of the body. The device is fabricated by an epitaxial layer/double buried region process.

Abstract: A method of operating a switching relay with inductive coils by a microprocessor control to prevent the transient electro-magnetic noise caused by the switching relay from resetting the microprocessor and restarting the program at the beginning. Prior to switching a relay a code is loaded in the memory of the control. After the relay switching noise causes a reset, the control detects the code and jumps back to its proper place without a disruption in its operation.

Abstract: A power line filter suppresses or dissipates and clamps short rise time high voltage transients carried by power transmission lines and provides continuous protection against continuous type induced noise. The power line filter includes one or more modules connected to either direct current or alternating current power lines to protect sensitive electrical equipment from the transients and continuous noise. The module used with a direct current power line includes a continuous suppressor connected between a source and load, and a selenium surge suppressor and a metal oxide varistor connected in parallel across the source. The module used with an alternating current power line includes a continuous suppressor connected between the source and the load, and a selenium surge suppressor and a gas tube connected in parallel across the source. The module used with the alternating current power line can also include a metal oxide varistor also connected in parallel across the source.

Abstract: The device, for AC operation, is applicable more especially to the protection of very high tension installations. It comprises a rectifier (12), a comparator for comparing the rectified current and a threshold value (s) and for making, in the case of overshoot, a new comparison after a time equal to and 1/2T+.DELTA.T, T being the nominal period of the AC current and .DELTA.T a fraction of T of the order of a tenth, after overshoot. The new comparison is made with a circuit comprising a memory (22), a timer (24) and a circuit (34) including two inverters and an AND gate. Tripping is produced if overshoot occurs during the new comparison.

Abstract: An intermediate repeater or a regenerative repeater has a circuit arrangement for the coarse protection against surge voltages, the arrangement comprising current supply separating filters for the remote feeding via a remote feed current path, fed via the inner conductor of a coaxial cable, which contain a low-pass filter, respectively. In the case of a circuit arrangement of this type, noise pulses, which a surge voltage arrester causes, are to be greatly reduced with respect to edge steepness. To this end, a series connection is provided containing the surge voltage arrester and an inductance, which series circuit, via a low-pass filter disposed outside of the remote feed current path, is connected between the low-pass filters of the current supply separating filters to the remote feed current path and to a connection of the outer conductors of the cables.

Abstract: A power latch circuit uses first and second bipolar transistors responsive to an actuate voltage to latch into a conductive state with power supplied to a computer and a third bipolar transistor powered by the latch circuit and responsive to a deactivate voltage from the computer to place the first and second transistors in a deactivated state to remove power from the computer and itself. It further uses an FET in parallel with the third bipolar transistor and activated directly from the DC power supply when the second transistor is deactivated to latch the first and second transistors in the deactivated state in spite of voltage fluctuations on the deactivate line which might otherwise cause the latch circuit to reactivate. As an FET, it uses little current through its gate compared to alternative bipolar devices while the latch circuit is deactivated.

Abstract: A case for accommodating an electronic circuit for an electronic control system mounted on a vehicle is formed of an electric conductor and is electrically isolated from the grounding terminal of the electronic circuit which is provided on a printed substrate. Further, the outer boundary of a signal line for signal transmission between the electronic circuit and external circuits or sensors of the case is connected to the case through capacitors, thus preventing the faulty actuation of the electronic control system which otherwise might be caused by the electromagnetic wave.

Abstract: A circuit for attenuating interfering voltage excursions occurring in either the common mode or transverse mode. An isolation transformer having primary and secondary windings separated by a conductive grounded shield has connected across one or both of its windings a shunt path comprising a capacitor in series with a breakdown device of predetermined bi-directional threshold conduction level with a dead band.

Abstract: A power line transient surge suppressor circuit features a nonlinear surge-bypassing network connected to bypass line surges around electrical loads connected to circuit output terminals. A fuse is inserted in series with the network, and blows in the event of short-circuit failure of a regulator device in the network. A thermal cut-out preferably of the irreversibly actuated type is inserted in series with the suppressor circuit input. A current-limiting heater resistor connected in parallel with the fuse supplies heat to trip the cut-out after the fuse blows, thereby permanently terminating power output to the loads. A similar suppression network is provided for the earth lead in three-wire systems.

Abstract: A pair of MOSFET power transistors are connected in a push-pull configuration to drive a tapped transformer and a load. A pair of diodes and an energy coupling circuit containing a capacitor and resistor in parallel bias the transformer primary in such a manner as to limit transients in a nonconducting MOSFET when the other MOSFET is conducting, aided by a drop in voltage at an inductor (ferrite bead) network which develops at the moment of MOSFET transistor conduction. This is due to a momentary change in the impedance ratio.

Abstract: An AC power line transient suppression circuit comprises a bi-directional series breakdown element in combination with a series inductor and a shunt capacitor.

Abstract: Apparatus for detecting, in advance, by a desired length of time, the imminent failure of electric output power provided by an electric power supply due to the reduction or loss of input power. The magnitude of the voltage on an energy storage reservoir capacitor is monitored for deriving a voltage signal proportional to the rate of change thereof. The rate of change voltage is multiplied by a voltage proportional to a desired early warning time interval and this product is added to a voltage proportional to a minimum value of voltage on the capacitor, thus representing an amount of stored energy sufficient to sustain normal output power for a desired time interval. The voltage derived by the adding means is compared with the voltage on the energy storage capacitor for signalling imminent power supply failure when the compared voltages are equal.

Abstract: An overcurrent relay comprises an input transformer (7), a rectifying circuit (8), a level detecting circuit (9) for providing an operation signal (S.sub.1) when a direct current signal voltage (E) exceeds a predetermined value, a determining means (10 to 15) for determining a time period of at least the positive and negative components of an ac signal voltage (V.sub.1) for providing a determination signal (S.sub.6) when the determined time period exceeds a predetermined time period, and a blocking means (16 and 17) responsive to the determination signal (S.sub.6) for blocking the operation signal (S.sub.1) from being output. In the case where the alternating current input current (I) and the ac signal voltage (V.sub.1) involve an attenuated direct current component due to magnetic saturation of a current transformer and the like, the reset time period of the operation signal (S.sub.1) is prolonged, while that time period of the ac signal voltage (V.sub.

Abstract: Device for indicating the positions of printed circuit cards with respect to their connectors, said cards belonging to an operational system in which each of them carries logic components and has a terminal surface carrying conductor elements able to come into contact with the corresponding conductor elements of an electrical connector, the corresponding conductors of the connector and of the card being able to occupy three relative positions: a first or safe contact position between the corresponding conductor elements of the connector and of the card, the card being correctly positioned relative to its connector, a second intermediate or non-safe contact position between the corresponding conductor elements of the connector and of the card, when the latter is being inserted or removed with respect to its connector, and a third or contact break position between the corresponding conductor elements of the connector and the card, when the card is completely withdrawn from its connector, wherein the device has

Abstract: An electric switching surge protector comprising a non-linear, voltage and frequency sensitive RC network connectable between earth and a phase of a switch controlled, AC electric load circuit. The RE network includes a linear resistance component; a non-linear resistance component connected in parallel with the linear resistance component and having a pre-determined knee-point voltage value; and a capacitance component connected in series with the parallel connected linear and non-linear resistance components. The capacitance component is operative to decouple the resistance components from the circuit at power supply frequency but to couple the combined resistive impedance of the parallel connected linear and non-linear resistance components effectively into the circuit under high frequency conditions. The capacitance component is further operative to increase the rise time of that portion of a steep fronted surge which exceeds the knee-point voltage value of the non-linear resistance component.

Abstract: A system responsive to the voltage of a motor vehicle battery when the vehicle engine is not running operates to disconnect the battery from the vehicle electrical loads prior to the point at which the battery becomes too discharged to restart the vehicle engine. The apparatus which operates to disconnect the battery from the loads is inhibited if an abrupt battery voltage drop indicative of vehicle entry is sensed, and the inhibit is maintained for a timed period sufficiently long in duration to allow entry of the vehicle and starting of the engine.

Abstract: The invention is a controlled ferroresonant power supply with an improved feedback circuit resulting in improved output stability. The feedback circuit is responsive to the low voltage secondary output of the power supply to provide a variable output signal to activate the switch which controls the resonant winding circuit. The improved feedback circuit is responsive to the rectified AC low voltage secondary output for only a portion of its frequency period.

Abstract: An apparatus for protecting a low-tension electric line (31) against disturbances with very steep slopes, said apparatus having a box (9) with a plurality of compartments (10, 15, 22, 26) in series which is equipped with limiter units such as dischargers and is disposed upstream from the line which is to be protected.It includes upstream from the box an electric conductor (3) of appreciable length surrounded by a metal tube (4) which is closed at its ends by insulating windows (5, 6) and separated from said metal tube by a solid or gaseous insulant (7).Application to the protection of electric power lines against disturbances due to powerful nuclear explosions.

Abstract: A current sensing circuit that controls a contactor that connects a load to power lines. The circuit provides an initial momentary delay period after energization of the circuit and before operation of the contactor to permit transients and other short duration anomalies to die out. An immediately succeeding second momentary delay period during which the contactor operation cannot be changed, assures that an initial inrush of current to the load will not cause a fault signal to erroneously operate the contactor. When a fault signal does cause the contactor to be operated, the circuit cannot be set back to its intended operation condition until energization of the sensing circuit is manually interrupted and reestablished. During normal operation of the circuit when current on the power lines is within acceptable limits, the circuit is latched in its proper operating mode.

Abstract: A circuit for use with logic circuitry preventing any transients due to the power down and power up conditions of a power supply from causing any false or random operations of the logic. The turn off transients are suppressed by a reset signal to the logic circuitry generated by a timing module which is triggered when it detects an absence of AC signal over a specified period of time and is then held in a reset mode until the power supply voltage completely decays. The turn on transients are suppressed by a reset signal to the logic circuitry generated by the timing module, which is held in a reset mode until the power supply voltage has stabilized.

Abstract: A circuit for protecting telephone lines from AC hazardous voltages. The circuit includes an amplitude discriminator triggered at a predetermined voltage level connected to the telephone lines, and providing an output pulse for each zero voltage crossover of the hazardous voltage. A digital pulse counter counts a predetermined number of output pulses from the amplitude discriminator, which in turn operates a switch after the predetermined number of pulses are counted, opening the telephone lines between the central office and the telephone instrument until the hazardous voltage has been removed from the lines.

Abstract: A method and apparatus for sensing the clearance of a fault current on an ac transmission line and providing a fault cleared signal for closing a current limiter bypass switch includes the technique of successively sensing half cycles of current magnitudes of the system after establishing a predetermined fault current threshold and producing a fault clear signal only when a signal indicating the threshold has been exceeded is followed by two subsequent signals indicating that the threshold has not been exceeded by the two half cycles of current.

Abstract: The invention is an electronic isolation and surge suppression system including a housing defining cord and socket openings and retaining a surge suppressor connected to one end of an electrical cord, the other end of which terminates with a plug adapted for connection to an AC power source. Also retained by the housing are a plurality of multiple terminal electrical socket means and an electrical circuit connecting the sockets in a parallel combination that is in series with the suppressor. The electrical circuit includes an electrical filter connected between each of the socket means and the suppressor. Large voltage surges are eliminated by the suppressor, while the individual filters provide electrical isolation between electronic equipment connected to the individual sockets and isolation from AC power line noise and transients.

Abstract: A static instantaneous overcurrent relay with reduced transient overreach is provided for use in protecting an a-c power line from overcurrents. The relay operates on an input signal representative of the magnitude of the current in the a-c power line and develops a relay output signal when the magnitude of the current reaches a predetermined magnitude. In a preferred embodiment, the relay includes a level detector circuit for receiving the input signal which is in the form of a pulsating waveform having the same frequency as the a-c power line. The level detector circuit develops a discrete level detector output signal in response to each pulse of the waveform which attains a magnitude representative of the predetermined magnitude. Output circuit means is coupled to receive the discrete level detector output signals and includes temporary inhibit means for inhibiting the development of the relay output signal until the output circuit has received two of the discrete level detector signals.

Abstract: Circuitry for generating tripping and blocking signals for the protection of electrical components included in electrical power supply networks as a result of the occurrence of faults therein provides multiphase pole tripping in the event that, after a single pole tripping has been executed, a new single phase fault occurs in any of the remaining phases of the electrical power supply network. Respective tripping and blocking signals are generated for each phase of the electrical power supply network in dependence on whether the fault lies ahead or behind the electrical component to be protected, respectively, in response to measurement of the voltae and current associated with transient waves generated by faults associated with each electrical power supply network phase.

Abstract: A programmable fault detecting relay for fluid cooled electrical apparatus utilizes a pressure transducer to provide an electrical input to an electronic discriminating circuit. The circuit discriminates between through fault pressures and internal fault pressures and provides an output upon the occurrence of an internal pressure fault.

Abstract: A method of, and apparatus for, detecting fault currents, such as short-circuits in electrical loads, especially at direct-current supply networks, wherein there is produced a current signal corresponding to the load current and compared with a reference value and when a difference signal appearing as a result of such comparison exceeds a threshold value such is employed as a triggering criterion. The rise or slope of the current signal is detected and the reference value is obtained by storing the value of the current signal present upon detection of a predetermined rise.

Abstract: A ground leakage current interrupter circuit including a transformer having a pair of balanced differential primary windings and a secondary winding, a fault detector for monitoring the output of the secondary winding and producing a fault signal in response to increases in the level of the secondary winding output that occur at greater than a predetermined rate, and a circuit interrupter responsive to the fault signal produced by the fault detector. Preferably, the fault detector includes a level detector for producing the fault signal in response to secondary winding output levels greater than a reference signal level, and a reference supply that varies the reference signal level in dependence upon the level of the secondary winding output so as to prevent production of a fault signal in response to increases in the secondary winding output that occur at less than the predetermined rate.

Abstract: A capacitor divider type high alternating voltage monitoring apparatus incorporating a filter with a switchable gain/frequency characteristic for removing the effect of d.c. voltage error arising from trapped charge on the capacitor divider.

Abstract: Increased versatility in crowbar overvoltage protection for regulated power supplies is provided by a tracking circuit which allows setting the overvoltage limit at a predetermined increment above a programmable output voltage. In addition provision is made for programming up the crowbar protection circuit rapidly to anticipate the rise of voltage in the main power supply and for delaying the programming down of the protection circuit to allow the main power supply voltage to decay without triggering the protection circuit.

Abstract: A harmonic distortion attenuator in an AC power supply for reducing electrical energy consumption through the suppression of transient voltages in power supply lines or the like connected to the circuitry wherein a threshold voltage clamp, responsive to a transient, closes an electrical path between the power supply lines. A triac or current responsive device is provided in parallel with the threshold voltage clamp to shunt the current flow from the clamp when the current through the clamp rises above a predetermined limit.

Abstract: Suppression circuit for transient noise pulses in which the magnitude of the pulse is limited to the threshold value of a selected breakdown device that is equally effective with voltage excursions of either polarity, and which includes means to reduce the high frequency content of the noise pulse and radically attenuate any tendency for oscillation.

Abstract: An inrush current restraint circuit, for use with a typical overcurrent minimum pickup circuit of a power system switching device, such as a recloser or sectionalizer, for raising the initial overcurrent minimum pickup value upon closure of the switching device to a selected value, then linearly returning this pickup value to normal within a selected period of time. The minimum pickup circuit is actuated by the voltage drop across a current sensing resistor, through which a current signal proportional to current in the power system is passed. The initial pickup overcurrent value is increased by providing another current path in parallel with the current sensing resistor when the switching device is closed. A timing capacitor is discharged each time the switching device is open, then charged from a constant current source each time the switching device is closed.

Abstract: Ground fault detection apparatus improved to include detector circuiry for providing an output current responsive to imbalance in the alternating currents flowing to and from a load only if it be of sustained character and of sufficient amplitude. The detector circuitry discriminates against responses to imbalance current primarily consisting of infrequent short-duration high-amplitude spikes characteristic of transient disturbances in favor of responses primarily consisting of the sustained, relatively long-duration rectified sinusoidal waveforms characteristic of ground fault conditions, even where the average level of the transient disturbance component of the imbalance current is equal to or in excess of the average level of ground fault component.

Abstract: A circuit breaker apparatus is taught which includes three time delayed modes of interruption and an instantaneous interruption. A long time delay mode is taught for interrupting overload current in the line to be protected. The latter time delay is inversely proportional to the square of the overload current. A short time delay mode is taught for providing a circuit breaker tripping operation after a predetermined fixed time delay when the current flowing in the line to be protected exceeds a predetermined amount.

Abstract: A starting relay for a power transmission line protection system.Where long line sections have to be protected, confusion can arise between normal heavy loads and distant faults having comparable line impedance. The invention provides a starting relay which limits operation of the normal distance relay to conditions within the starting relay characteristic, this being derived by phase and amplitude monitoring of the load at the relay station. The characteristic accepts heavier line currents at potentially normal phase angles than at abnormal phase angles.Certain unbalanced faults do however exhibit normal phase angles and these are detected by substantial line voltage drops. A described combination of phase, current and voltage detectors thus covers substantially all faults.The starting relay finds particular application in a carrier-blocking fault detection scheme employing duplicates of the basic characteristic.

Abstract: This invention provides overload protection to power components such as power transistors. A pair of driver transistors is connected in push-pull configuration and is coupled through an auto transformer to a pair of power transistors also connected in push-pull configuration. An impedance-matching transformer couples the pair of power transistors to a load circuit, such as a speaker. A low turn winding is connected in series with the secondary winding of the impedance-matching transformer, and drives a high turn winding in a silicon controlled rectifier trigger circuit which is triggered "on" when an overload condition exists in the low turn winding. Upon conduction of the silicon controlled rectifier, a switching transistor is switched "on" and this, in turn, switches "off" a power disabling transistor which is connected directly to, and in power disabling relation to, the pair of driver transistors.

Abstract: A system for the floating energization of a balanced load from a remote power supply via a pair of conductors, e.g., for feeding operating currents to repeaters of a telecommunication link, includes a circuit breaker controlled by an open-circuit sensor and an unbalance sensor through a memory unit provided with a pair of storage circuits. These circuits, designed to store a malfunction signal emitted by either of the two sensors until the arrival of a resetting signal, inhibit each other to prevent the registration of more than one malfunction at a time.

Abstract: This high-speed differential protective arrangement discriminates between a fault occurring in a differentially-protected zone of a power circuit and operation of a lightning arrestor connected to the power circuit in said zone. The protective arrangement comprises a relay which operates in response to such a fault but which remains inactive despite operation of the lightning arrestor. Despite this insensitivity to lightning-arrestor operations, the relay is still able to operate relatively fast at levels of fault-produced voltage across input terminals to the protective arrangement much lower than those developed across these terminals by lightning-arrestor follow-through current.

Abstract: An automatic recycle circuit is disclosed for use in a process or apparatus of the type wherein process or equipment conditions are monitored to detect an abnormal condition. The automatic recycle circuit accepts inputs from monitor circuits which are intended to cause recycle operation and monitor circuits which are intended to cause complete shutdown and reacts appropriately to each type of input. With respect to those inputs from monitor circuits which are intended to cause recycle action, the automatic recycle circuit is capable of permanently shutting down the process or apparatus if the detected abnormal condition has a duration exceeding a first predetermined time or abnormal conditions are detected a predetermined number of times within a second predetermined time period.

Abstract: In a static protective relay device utilizing a converter including a bandpass filter which causes time delay during transients, there are provided a detector responsive to the output from the converter, and means for preventing misoperation of the detector due to an attenuating oscillation of the output caused by the transient phenomenon of the converter which occurs during attenuation of the output.

Abstract: An improved in-band signal-to-noise ratio monitor is used in conjunction with the receiver of an FSK relaying system. The improved monitor measures the signal-to-noise ratio both prior to and after the receiver input signal is filtered by a narrow bandpass filter. The magnitudes of the measured ratios are compared and, if all signal-to-noise ratio permissives are not satisfied, the tripping function of the relaying system at the receiver or local station is blocked or inhibited.

Abstract: In an arrangement for level and sequence detection in a directional wave detector, which has a three-phase directional wave detector with two inputs per phase and three single phase and one three-phase tripping output and one three-phase blocking output, with a level detector with one partial detector for each of the single-phase tripping outputs and the three-phase blocking output, the level detector is provided with a further partial detector which is connected to the three-phase tripping output of the wave detector and the two partial detectors which are connected to the three-phase outputs of the wave detector have a lower reference level than the other partial detectors which are connected to the single-phase tripping outputs of the wave detector.