Abstract: Low voltage electric switchgear equipment includes a central programmer unit electrically interconnected with electronic main and branch circuit interrupters within the same enclosure and used with a multi-phase power distribution circuit. Indicating diodes are arranged on each of the circuit interrupters for signaling the occurrence of an overcurrent condition. The same indicating diodes are arranged for responding to address commands generated by the field programmer as to the exact location of each circuit interrupter within the enclosure.

Abstract: An inrush restraint in a fault indicator disables trip in response to the current in the cable being monitored changing from reset to trip values within a predetermined period.

Abstract: A faulted circuit indicator includes an inrush restraint circuit that suppresses a trip signal when an inrush current rises from below a minimum value to a trip value within a predetermined time and then drops again to another value such as the trip value. According to various aspects the restraint ends after a fixed time or after a variable time. According to another aspect a second trip circuit overrides the inrush restraint circuit when the current rises a given amount beyond the first trip value.

Abstract: A circuit breaker containing an electronic trip unit utilizes a digital keypad and display to enter and display the trip parameters. The trip parameters are determined by means of a setpoint value that is incremented by means of an algorithm whenever the trip parameters are changed.

Abstract: The disclosed faulted current indicator senses current in a line having a breaker or fuse, and avoids tripping in response to current inrush signals by producing a trip signal in response to an overcurrent occurring for an overcurrent duration which is inversely related to the magnitude of the overcurrent and is faster than the overcurrent operating time of the breaker or fuse. In one embodiment, this involves operating a current protection device in response to an overcurrent occurring for a second overcurrent duration inversely related to the magnitude of the overcurrent according to a first characteristic, and adjusting the first overcurrent duration to follow a second characteristic having variations substantially the same as the first characteristic but having a shorter first overcurrent duration than the second overcurrent duration.

Abstract: An automatic override circuit is responsive to the magnitude of instantaneous current flow through a monitored conductor to produce an output signal which can actuate a solenoid or a ground fault interrupter to automatically trip a circuit breaker in repsonse to an excursion of current flow which exceeds a predetermined maximum current overhead level. The short circuit protector can automatically override a thermal trip delay and cause the circuit breaker to trip instantly or delay tripping for a prescribed period of short circuit events which exceed the maximum current overload level. In one embodiment, a control signal is generated which actuates a solenoid which is coupled to a thermal magnetic circuit breaker. In an alternative embodiment, the control signal is utilized for automatically triggering a ground fault interrupter.

Abstract: Instantaneous trip capability is provided to an electronic circuit breaker, which is of the type that generates trip signals by accumulating squares of power line current samples and thresholds the accumulation results. Samples of power line current are taken directly from the current transformer and analog-to-digital converter cascade generating them. The analog-to-digital converter is of an oversampling type, using a delta-sigma modulator. The samples are threshold detected against a prescribed threshold value without previous squaring, integration and detection. The threshold detector result is checked for two consecutive overcurrent indications before an instantaneous trip signal is generated.

Abstract: A distribution line switchgear control which is particularly suitable for use with recloser switchgear which requires small amounts of power from the control for operation. The control is most usefully powered for continued operation by small amounts of line current provided through a power source current transformer and includes multiple capacitors which are arranged in a cascaded control power supply having a plurality of isolated stages. The line current is precisely monitored through current transformers by the control which causes the recloser to trip, reclose and lockout, as is appropriate to protect the distribution line and distribution electricity. Inhibit means prevent the control from issuing a trip signal, unless sufficient energy exists in a trip portion of the cascaded power supply. A variety of volatile timers and counters enable the control to cause the recloser to trip, reclose and lockout.

Abstract: A current overload tripping device having a time-delayed leading tripping action during uneven loading of the phases of a multiphase circuit. The tripping device includes a current pickup for each phase wherein the current pickup members are connected in series with one another and with an electromagnetic converter. Each of the current pickup members comprises a winding surrounding a magnet yoke of an electromagnetic tripping device of each phase and the electromagnetic converter comprises a temperature/time-dependent device operating to provide a time-delayed tripping signal.

Abstract: An electronically controlled lighting panelboard characterized by a power line panelboard having a plurality of remotely controlled circuit breakers for opening and closing circuits to corresponding loads. Each circuit breaker is interconnected to an interface which in turn is connected by a multi-conductor cable to an electronic controller or computer.

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 distribution line switchgear control which is particularly suitable for use with recloser switchgear which requires small amounts of power from the control for operation. The control is most usefully powered for continued operation by small amounts of line current provided through a power source current transformer and includes multiple capacitors which are arranged in a cascaded control power supply having a plurality of isolated stages. The line current is precisely monitored through sensing current transformers by the control which causes the recloser to trip, reclose and lockout, as is appropriate to protect the distribution line and distribution electricity. Inhibit circuits prevent the control from issuing a trip signal, unless sufficient energy exists in a trip portion of the cascaded power supply. A variety of volatile timers and counters enable the control to cause the recloser to trip, reclose and lockout.

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: The present invention relates to an electronic overload relay which uses a schmidt trigger circuit or a CMOS integrated circuit, wherein the electronic overload relay includes an automatic return circuit connected in parallel between the output terminal of a NOT-gate and the input terminal of a succeeding NOT-gate, an instaneous operation characteristic circuit connected in series between one terminal of a variable resistance and the input terminal of the succeeding NOT-gate, and a temperature compensation circuit connected in parallel to the secondary coil of the current transformer.

Abstract: A solid-state trip device including an instantaneous trip device formed by arc detectors 46R, 44S, 46T located in proximity to the main contacts 17R, 17S, 17T of the circuit breaker 10. The light signals emitted by the arc detectors 46R, 46S, 46T are transmitted by optical fibers 48 to a light-sensitive electronic component which emits an arcing signal. This arcing signal causes tripping of the circuit breaker 10 only if a fault signal is present.

Abstract: Output current of secondary winding of a current transformer (21) corresponding to current value of an A.C. power line (1) is led to series connection of an electric power circuit (500) and resistors (40,41); voltages obtained across the resistors (40,41) are input to a time delay circuit (70) which ignites a load break contact (200) in the A.C. power line (1) when an accident overcurrent flows in compliance with tripping characteristics. A quasi output signal or reference signal for testing of D.C. voltage is applied to the time delay circuit (70) when any current does not flow in the A.C. power line, thereby to enable tripping test of the circuit breaker as it is connected to the actual power line.

Abstract: A universal programmable logic control device for monitoring the current of a circuit and for signalling a circuit control device, such programmable logic control device including; electrical power circuitry for activating the circuit control device; electrical circuitry for monitoring the current in the electrical circuit, such electrical circuitry including, adjustable electrical signal input circuitry to match the programmable logic control device to the electrical current in the circuit, adjustable pick-up circuitry for adjusting the level of the current monitored in the electrical circuit, adjustable time circuitry for adjusting the time duration of the selected level of electrical current, so as to command the electrical power circuitry to activate the control device when the electrical current in the electrical circuit reaches the selected level and time duration; and a zenor diode in reverse mode for controlling the level of voltage applied to the adjustable pick-up circuitry and time circuitry substa

Abstract: A time delay circuit of a circuit breaker has: a comparator (35) for comparing an input signal (Ex) and a reference value (Ey) and for switching on and off for charging of a capacitor (38); a reference voltage setting circuit (37) for setting the reference voltage (Ey) corresponding to a value of a rated current of an A.C. power line; a processing circuit (45) for calculating a ratio of the input voltage (Ex) corresponding to a value of overcurrent to the reference voltage (Ey); and a voltage/current conversion circuit (44) for converting an output voltage of the processing circuit (Ez) to a current output (Ib) which is to be charged in the capacitor (38) for determining a delay time.

Abstract: A circuit breaker device comprises a rectifier circuit connected to the secondary winding of the current transformer to convert the AC secondary current into a unidirectional current. A DC constant voltage power supply circuit is connected across the output terminals of the rectifier circuit and produces positive, negative and intermediate potentials. A time delay circuit powered from the power supply circuit and connected to receive the output signal of said differential amplifier circuit proportional to said unidirectional current and producing a predetermined time delay with respect to a predetermined magnitude of said unidirectional current. An electromagnetic trip coil connected in series with said switch circuit, the series circuit of said electromagnetic trip coil and said switch circuit is connected to be energized by the output of said rectifier circuit.

Abstract: In a circuit breaker, a timer circuit is employed for delay interrupting operation in case of line failure. The timer circuit includes at least a peak value converting circuit, an effective value converting circuit, a switch, and a switching control circuit. When the failure current is lower than a predetermined threshold level, a long-time delay tripping circuit of the timer circuit is operated in response to an effective value voltage from the effective value converting circuit. When the fail current exceeds over the threshold level, the long-time delay tripping circuit is operated in response to a peak value voltage from the peak value converting circuit so as to avoid an adverse influence of the saturation characteristic of the current transformer.

Abstract: An integrated protection unit is a circuit breaker which includes basic overcurrent protection facility along with selective electrical accessories. A molded plastic accessory access cover secured to the integrated protection unit cover protects the accessory components contained within the integrated protection unit cover from the environment. A combined overcurrent trip actuator and multiple accessory module is either field-installed or factory-installed within the integrated protection unit. A separate actuator-accessory module is selected for different combinations of accessory functions. One such actuator-accessory module provides ground fault protection along with remote trip facility.

Abstract: In the overcurrent tripping unit for a circuit breaker, current transformers are provided for detecting currents flowing through respective phases of a main circuit, the secondary outputs of the current transformers are star connected, the primary outputs are polyphase full-wave rectified, the voltage drop based on the rectified positive/negative direct output of each phase is directed by first and second resistances to be applied to the control means, and a ground fault current is detected based on the secondary outputs of the current transformers to be applied to the control means.

Abstract: A circuit breaker in which the levels of overload currents are detected with increased accuracy and which functions properly even just often its load-connecting contacts are closed. A rectifier circuit converts outputs from current transformers into currents flowing in one direction, the current transformers detecting the currents through main the paths. A power supply circuit and current-detecting resistors are connected in series with the output of the rectifier circuit. Differential amplifiers amplify the potential differences across each resistor. If the power from the power supply circuit is insufficient to operate the differential amplifiers and a timer normally, an inhibiting circuit prevents a switch circuit from being closed.

Abstract: When a current of a distribution line is increased to about two times of a rated current of a circuit breaker, the circuit breaker is operated to open the distribution line with a comparatively long time lag such as 100 seconds by a long time-lag tripping circuit of the circuit breaker, on the other hand, in case that a current of 80-90% of the rated current have continuously flowed before the current is increased as mentioned above, the time lag which is set in the long time-lag tripping circuit is shortened.

Abstract: A reclosing relay for use in an electrical power system with a circuit breaker for clearing line faults by tripping and reclosing. The breaker has auxiliary contacts defining the state of the circuit breaker as open or closed. The reclosing relay includes a circuit responsive to the auxiliary contacts for producing a first signal representative of the state of the breaker and another circuit for generating a second signal when a loss of power to the reclosing relay is anticipated.

Abstract: A circuit interrupter includes a circuit arrangement for sampling a conditioned current value and determining operating characteristics related to the current flow through an electrical circuit. Also included is a circuit arrangement for comparing the operating characteristics to preselectable tripping parameters and circuit arrangement for initiating a trip condition when an operating characteristic exceeds a corresponding tripping parameter. Additionally, a circuit arrangement for selecting and displaying operating information in an understandable format and in an easily accessible position on the circuit interrupter is also included.

Abstract: A solid state overcurrent detector is provided with a current sensor means (200) having an OR circuit (130) connected by its input terminals to output terminals of burden circuits (41,42,43). A phase selecting circuit (400) for selecting the largest phase is connected by its input terminals to the output terminals of the burden circuits. The output terminal of the phase selecting circuit (400) is connected through a signal converting circuit (90) and an A/D converter (100) to a microcomputer (110) having a first level-discrimination circuit (1001) and a first time-current operation circuit (1002) with inverse time-current characteristics for various time interruptions responding to an amount of overcurrent. The output terminals of the OR circuit (130) are connected through a second level-discrimination circuit (140) to a second time-current operation circuit (150) for instant interruption.

Abstract: A circuit breaker having three level discriminating circuits and time-current operating circuits, respectively corresponding to an instantaneous releasing, a short time characteristic releasing and a long time characteristic releasing of disconnectable contacts.

Abstract: A self-protective driver circuit with automatic reset features is provided for a marine electric fuel pump (2, 102) energized by the boat battery (4, 104) as controlled by a series connected semiconductor switch (6, 106). A first stage protective subcircuit (28, 128) senses surge current through the semiconductor switch at initial turn on with the fuel pump at rest and causes the semiconductor switch to depart from saturated conduction and thus limit the current until the pump starts running and the current decreases to a safer level, to protect the semiconductor switch from excessive current.

Abstract: A circuit interrupter includes a circuit arrangement for sampling a conditioned current value and determining operating characteristics related to the current flow through an electrical circuit. Also included is a circuit arrangement for comparing the operating characteristics to preselectable tripping parameters and for initiating a trip condition when an operating characteristic exceeds a corresponding tripping parameter. Additionally, a circuit arrangement for establishing a ground fault current limit using a minimum number of components to achieve a wide range of possible settings, is also included.

Abstract: An improved current-sensing arrangement and method are provided for supplying a signal that suitably represents line current over a wide current range. The current-sensing arrangement utilizes the signals from an iron core transformer and an air core transformer along with transition and scaling arrangements to provide the sensed current signal. The range of operation includes currents for which the iron core transformer exhibits saturation effects and currents for which the air core transformer does not contribute to the combined output signal. Additionally, the range of operation includes currents for which both the transformers contribute to the combined output signal.

Abstract: A circuit interrupter includes a circuit arrangement for sampling a conditioned current value and determining operating characteristics related to the current flow through an electrical circuit. Also included is a circuit arrangement for comparing the operating characteristics to preselectable tripping parameters and for initiating a trip condition when an operating characteristic exceeds a corresponding tripping parameter. Additionally, a circuit arrangement for initiating a hardware override trip condition using a minimum number of components upon sensing an override signal, is also included; the override signal representing a limit selectable from a range of values.

Abstract: Electronic trip units employed within static trip circuit breakers are individually calibrated and automatically adjusted to ensure that the trip transfer characteristics are within specification requirements. A trimming network within the trip unit circuit contains a plurality of parallel resistors each separately connected within the circuit by means of a fusible link. Test input and output values are compard to idealized values that are binary-weighted within a look-up table in the test equipment computer. The percent correction required is determined and the appropriate links are interrupted to provide ideal trip response.

Abstract: The digital solid-state trip release is equipped with a watch-dog which monitors the periodic running of the information processing controlled by the microprocessor. When a disturbance or a delay occurs in the periodic cycle, the watch-dog first emits a reinitialization order applied to the microprocessor input to attempt to rerun the periodic cycle. If this attempt is unsuccessful, the watch-dog emits a circuit breaker tripping order.

Abstract: A digital solid-state trip unit of an electrical circuit breaker is equipped with an electrical contact wear indicator enabling the degree of wear of these contacts to be known. Each time the circuit breaker performs a break, the microprocessor determines a contact wear value, in terms of the maximum value of the current broken. The correspondence between the wear value and the current broken is stored in a ROM memory and the successive wear values are added in a NOVRAM memory whose contents are representative of the degree of contact wear. These contents can be displayed to indicate to the user that the condition of the contacts has to be checked.

Abstract: A timer controlled multipole circuit breaker has a pair of breaker contacts in each pole which are connected to load and line terminals respectively provided in the current path of each pole. Incorporated in the breaker is electric timer for controlling to open and close the breaker contacts according to a predetermined timing schedule. The electric timer has its input end connected across the line terminals of the adjacent poles so as to be energized by the common power on the line terminals of the breaker without requiring any additional external wiring. The circuit breaker incorporating the electric timer of the present invention further provides a safeguard which inhibits the automatic reclosing of the contacts by the timer operation until the fault current condition is cleared.

Abstract: A circuit interrupter includes a circuit arrangement for sampling a conditioned current value and determining operating characteristics related to the current flow through an electrical circuit. Also included is a circuit arrangement for comparing the operating characteristics to preselectable tripping parameters and for initiating a trip condition when an operating characteristic exceeds a corresponding tripping parameter. Additionally, a fault indicating circuit arrangement energized by a backup energy source following interruption is also included as well as circuit arrangement for preventing interference to the display and operating circuits during power-up and power-down conditions.

Abstract: An instantaneous solid-state trip device has two threshold values providing an upper and a lower tripping threshold. A current increase rate detector determines, when a short-circuit occurs, the prospective peak current value and, if the peak value corresponding to the electrodynamic withstand of the circuit breaker is liable to be exceeded, causes a change of threshold to bring about tripping, as soon as the lower threshold is exceeded. This high-speed tripping favours short-circuit current limiting. When a short-circuit of a lesser importance occurs, the current variation is lower and the instantaneous trip release only trips when the upper threshold is exceeded. In most cases, this upper threshold is not reached and tripping selectivity can be easily achieved in the usual way. A break in the circuit connecting the sensor to the trip unit also causes the circuit breaker to trip.

Abstract: Programmed overcurrent protection control apparatus with selectable time-overcurrent operation to govern the interruption of current through at least one power line associated with either a ground phase or a power phase of a power system network is disclosed. A programmed processor is included to derive an overcurrent time-to-trip in accordance with sampled measurement current values of the power line and selected derivation constants stored in a memory look-up table. The derivation constants are selected from the look-up table based on derivation parameters which may be set and read by the programmed processor from time to time. The programmed processor utilizes the selected derivation constants to derive the time-to-trip over a number of predetermined time intervals during which the overcurrent condition persists.

Abstract: Microprocessor-based digital solid-state trip unit (48) generating an inverse time long delay and/or short delay trip by digital simulation of the heating and cooling of a bimetallic strip. A digital value (TETALR), stored in a RAM memory simulates the temperature of the bimetallic strip, this value being incremented when the current exceeds a preset pick-up (ILR) or on the contrary decremented if the current is lower than this pick-up (ILR). Tripping is caused when the stored value (TETALR) exceeds a maximum pick-up (TETAMAX). The microprocessor (48) computes the incrementation factor (DTETAE) in terms of the square of the current.

Abstract: A characteristic timer, for a protective relay which provides protection for a portion of an AC transmission line, exhibits a phase characteristic which is always integrating and a ground characteristic which changes from non-integrating to integrating as a function of input signal pulse width and a preselected cut off time. The ground characteristic begins to integrate upon expiration of the preselected cut off time or if the input signal pulse width exceeds a predetermined check level of magnitude during the cut off time. If the pulse width magnitude of the input pulse is less than or equal to the predetermined check level magnitude during the cut off time, the characteristic will be non-integrating.

Abstract: A microprocessor-based digital solid-state trip-unit for processing digital signals derived from analog signals supplied by current sensors. In order to reduce measurement error of the peak value of the signals due to signal sampling, the microprocessor samples a signal latched at the last peak. A countdown timer determines the latching time to include two or three peak values.

Abstract: The overcurrent trip levels of an electronic circuit breaker are selected by means of a variable resistance ladder network comprising binary encoded switches. The binary encoded switches reduce the size and cost of the trip unit, rendering electronic trip facility to a wider range of industrial circuit breakers utilizing both analog as well as digital processing circuits.

Abstract: A solid state overcurrent detector or an overcurrent interruptor using the same provided with a microcomputer for discriminating level of overcurrent and issuing a predetermined time-current characteristic, the microcomputer further comprises a means for actuating a charge-discharge circuit 119, which gives a simulated heat-discharge characteristic to give data for the microcomputer for accurate time-current operation in case a first overcurrent is such an amount not to interrupt the circuit and another overcurrent arises during discharging of heat due to the first overcurrent.

Abstract: A programmed overexcitation protective relay with selectable time-overexcitation operation to govern the interruption of energy to a piece of power equipment, like a transformer, generator or the like. A programmed processor is included to derive an overexcitation time-to-trip in accordance with sampled measurement voltage values of at least one power line supplying energy to the power equipment being protected, and selected derivation constants stored in a memory look-up table. The derivation constants are selected from the look-up table based on derivation parameters which may be set and read by the programmed processor from time to time. The programmed processor utilizes the selected derivation constants to derive the time-to-trip over a number of predetermined time intervals during which the overexcitation condition persists.

Abstract: Digital solid-state trip unit designed to provide protection against phase faults, notably overloads and short-circuits and optional functions, in this case ground fault protection and load shedding and restoring functions. Two parameter input switches (72, 74) are assigned to the optional functions to display, in the ground protection option the ground protection pick-up and the ground protection time delay, and in the load shedding option, the load restoring pick-up and the load shedding pick-up. Each option has a software program stored in a non-volatile memory corresponding to it.

Abstract: Solid-state trip unit having a unit (29, 50, 48) for digital processing of signals emitted by current sensors (16). The digital processing system provides the long delay, short delay and instantaneous tripping functions and delivers a tripping order to the relay (14). An analog processing unit (70) is connected parallel with the digital processing unit to transmit an instantaneous tripping order to the relay (14). When the digital processing unit operates, the analog unit pick-up level is higher than the digital instantaneous tripping pick-up and this pick-up is reduced to a lower or equal value, if the digital unit is inactive.

Abstract: An electronic overcurrent circuit interrupter utilizes a digital processor for performing RMS sampling of circuit current for comparison to stored long time and short time current values and time delays before tripping the breaker. A magnetic core current transformer is employed for providing an output current signal to the digital processor. Upon detecting core saturation, which occurs at high currents, an analog detection circuit interrupts the RMS sampling and causes the digital processor to time out the shortest pre-selected time delay before tripping the breaker.

Abstract: Microprocessor-based solid-state trip unit (48) processing digital signals derived from analog signals supplied by current sensors (16). The analog signals are applied to a calibration circuit (34), which adapts the output range of the analog circuits to that of the logic circuits, to obtain with an 8-bit Analog-to-Digital Converter (50) associated with a Multiplexer (29) a range equivalent to that of 12-bit processing systems.

Abstract: Circuit protection and protective relay functions are provided by common circuit elements under the control of a single processor unit. Voltage and current values are obtained on a continuous basis and these values are continuously monitored within the processor to determine the electrical status of a protected power distribution system. Upon the occurrence of an overcurrent or undervoltage condition, the circuit is interrupted by operation of a circuit breaker trip solenoid causing the breaker contacts to open. When the overcurrent or undervoltage condition ceases to exist, the circuit breaker contacts could be closed by operation of a controlled relay. The ROM and RAM storage elements within the processor unit are continuously tested and the circuit breaker contacts are opened upon indication that the ROM or RAM element is nonfunctional.