Abstract: A current differential protection arrangement for an electric power supply unit with a measured value pre-processing device and an analysis device that checks on the basis of a predefined dependence of a differential current on a stabilizing current (response characteristic curve) to determine whether the differential and stabilizing current values thus formed are in a blocking range or a triggering range, where an additional stabilization range is present in the blocking range. To avoid fixed-time blocking after an external fault with transformer saturation with such a protection arrangement, the analysis device in a stabilizing circuit contains a testing arrangement which checks the current values thus formed to determine whether they describe a point in the additional stabilization range. If this is the case, a blocking signal is produced, which activates the blocking device downstream from the testing arrangement.

Abstract: A microprocessor-based multifunction overcurrent relay for protecting power systems has a plurality of overcurrent elements implemented in a software program. Sufficient overcurrent elements are provided to accomplish a selected one of three independent applications, including feeder protection, motor protection, or breaker failure protection. The relay includes elements for selecting one application by the user from the three possible applications and produces output signals when an overcurrent condition is determined.

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 non-dissipative device for protecting an integrated circuit having multiple independent channels against overloading. The non-dissipative device includes an input terminal and an output terminal having an integrated switch connected therebetween which consists of an input portion, a logic gate with two inputs a control portion, and an output portion, all connected in series with one another. The device further includes a generating circuit for generating the on-times and off-times of the integrated switch, the generating circuit is connected between an output of the output portion and an input of the logic gate.

Abstract: A motor controller unit that employs standard motor contactors and electronic circuit breakers includes an electronic control module (ECM) for interfacing with the contactors and circuit breakers. Electrical connection with the circuit breaker electronic trip unit and the ECM is made by means of the circuit breaker rating plug. Electrical connection with the contactors and the ECM is made by means of externally-accessible terminal screws.

Abstract: A winch system including an electric motor is protected against an overload condition by use of a current sense device and a current limiting device. The current limiting device employs multiple current thresholds to account for normal current usage by the motor during an initial current inrush period and during subsequent normal operation. The current limiting device also references battery voltage to establish current thresholds as a function thereof and thereby establish shutdown conditions corresponding to consistent motor load conditions. Overall, the current limiting device is responsive to multiple winch device states of operation and more fully protects the winch system against damage due to an overload condition.

Abstract: A protective device for an electric distribution system capable of providing an easy inspection and confirmation of the setting for the operation characteristics of the device. The device includes an input unit for entering a setting of an operation characteristic of the protective device; a calculation unit for determining the operation characteristic of the protective device according to the setting entered by the input unit; and a display unit for displaying the operation characteristic determined by the calculation unit.

Abstract: Digital processing of current signals allows close matching of arbitrary time delay curves for a circuit breaker. An analog signal proportional to the current is sampled and digitized. Digital samples, with or without further processing, are used to select increment values from a look-up table for accumulation in a counter. The counter is decremented periodically to simulate cooling of the circuit being protected. The values in the look-up table are determined according to the desired time delay curve. Processing of the digital samples may include squaring samples, accumulating the squared values to form a subtotal which is compared with an instantaneous trip threshold, accumulating the subtotals for a time period equal to half a cycle of AC line voltage, taking the square root of the accumulated subtotals, and using that square root as the address for looking up the increment value.

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: An electrical switch with overcurrent protection communicates as a slave with a remote master station by sending return messages to the remote master station only in response to messages addressed to it. A portable unit plugs into the electrical switch and disables communications between the electrical switch and the remote master station. The portable unit then establishes communications with the electrical switch by sending a global message to the electrical switch requesting the unique address at successive baud rates until a return message containing the electrical switches' address is received. A communications module in the electrical switch transfers to a master mode in response to the global message in order to send the return message containing its unique address. It then reverts to the slave mode for response to subsequent messages from the portable unit containing the unique address.

Abstract: An integrated circuit breaker having several accessory functions along with automatic overcurrent protection, allows selection between the various accessory functions in different combinations. Separate switches are arranged on the circuit breaker to allow factory as well as field selection of the accessory function combinations.

Abstract: A digital circuit interrupter utilizing current transformers for operating power is provided with a re-chargeable battery to power-up the trip unit as well as to power the display after an overcurrent trip occurrence to enable an operator to determine both the magnitude as well as the cause of the overcurrent condition.

Abstract: A circuit interrupting device provides for operator selection of protection parameters for a neutral conductor separate from operator selected phase protection.

Abstract: A circuit protection device for use with an electrical unit comprises driver circuitry connected to the electrical unit and connecting means electrically connecting the device to the electrical unit to provide a voltage signal indicative of a voltage associated with the electrical unit. A voltage detector is connected to the connecting means and receives the voltage signal, and provides a conditioned voltage signal output representative of the voltage signal. An analog-to-digital converter receives the conditioned voltage signal output and converts the conditioned voltage signal output to a digital value. A digital processing device receives the digital value from the analog-to-digital converter and provides an output signal to the driver circuitry to turn off power to the primary if an error is detected.

Abstract: A power source circuit is provided having a high frequency transformer 16, a switching control circuit 15 connected with the primary winding of the transformer 16, rectifier circuits 17, 18 and 20 connected with the secondary winding of the transformer 16 for outputting a D.C. voltage to an external circuit, an alarm detection circuit 25, an excess current detection circuit 26, and an excess current detection delay circuit 28. When the alarm detection circuit 25 detects an excess current in supplying power source, the power source supply is suspended by turning off the output of the switching control circuit 15 after the lapse of the preset time. When the excess current flows after the lapse of the initial preset time t.sub.s from turning on the power source, the excess current detection circuit 26 detects it so that the output of the switching control circuit 15 is turned off.

Abstract: Control and self-monitoring system for an electrical apparatus comprising three poles, each including a closing coil and an opening coil, an opened auxiliary contact, and a closed auxiliary contact, wherein each of the poles is provided with a microprocessor receiving, in particular, information from the opened auxiliary contacts and controlling two static relays in series respectively with the circuit of the opening coil and in the circuit of the closing coil, the microprocessors being subscribers to a local bus comprising a serial bus under the control of a management member and connected to a processor station receiving the signals collected by the microprocessors and the signals issued by the protection devices or by the operator.

Abstract: A graphical representation of the current/time trip characteristic displayed on the operator's panel of an electronic trip unit for a circuit interrupter, has different indicia, such as different colors, identifying the representation of independent trip functions from those of dependent trip functions, thereby making the operator aware that adjustment of one of the dependent trip functions will also affect an adjustment of the other dependent portions of the current/time trip characteristic.

Abstract: An overcurrent detector circuit for a circuit-breaker includes two systems for overcurrent detection. In the first system, the level of the current detected by the current detectors 41 is converted to a digital signal by the A/D converter 91 at each 500 microseconds. The maximum value detector 92 selects the maximum value among these digital signals over each period of 12.5 milliseconds. When the maximum value is greater than a pick-up level, the square thereof is accumulated in the counter 95. In the second system, the calculation circuit 96 squares the digital signals of the A/D converter 91, and switches its outputs in order to the counters 97-1 through 97-5 at a period of 25 milliseconds. Thus, the four counters other than that currently coupled to the calculation circuit 96 hold together the squares of the digital signals accumulated over 100 milliseconds.

Abstract: A circuit breaker includes an electronic trip device which responds to sputtering arc-type faults. Level detectors compare the current in the protected circuit to a plurality of threshold levels and timers time the intervals that the current remains above each threshold, with the threshold levels and intervals selected to generate a response envelope for a trip signal which approximates, with a selected margin, the response of the protected circuit to introduction of a selected inductive load such as the starting of a motor into the circuit. If the sensed current falls below a threshold level which was being timed, the associated timer is not cleared unless the current falls below the lowest threshold, so that if the sensed current increases above the associated threshold, timing resumes where it left off, and a trip signal will be generated sooner than for an initial excursion above the threshold. Both analog and digital timer implementations are presented.

Abstract: The overload protection circuit 12 comprises a resistor bridge 20 with a low impedance sensing resistor r and high impedance resistors R1 to R4 which generates voltages Va and Vb at the inputs 32 and 34 of a comparator 22. Voltage Vb depend upon the value of the load current so that the comparator provides at its output 36 a control signal for opening the switching device 24 comprising a field effect transistor when the load current exceeds a maximum value. Resistor R5 reinforces the effect of the control signal. This circuit can be used in a system which comprises a central power supply unit 8 which powers a plurality of devices such as 4. The status of the circuit 12 is reported to the system 8 though line 14 and circuit 12 comprises a control circuit 26 which is responsive to set and reset control signals on lines 14 and 18 from the unit 8 to close or open the switch 26.

Abstract: The front panel of the trip device is formed by a flat screen display, for example liquid crystal, controlled by the trip device microprocessor. The display provides a permanent display of the information relating to the type of trip device, the tripping parameters and measured values, from data entered in the trip device memory. Display is in alphanumeric and/or graphic form.

Abstract: A microprocessor watch-dog monitor for electronic trip units includes an input transistor (Q1), a timing circuit (16), and a comparator circuit (18). The comparator circuit is formed of a first bipolar transistor (Q3) of the PNP-type conductivity and a second bipolar transistor (Q4) of the NPN-type conductivity.

Abstract: The short time delay circuit comprises a counter which is zero reset when the signal representative of the current is greater than or equal to a threshold, and controls count-down of an up-down counter, when the content of the counter reaches a preset value. A clock circuit controls the count-up and count-down frequency of the counter and up-down counter.

Abstract: A device for detecting a primary fault current at a three phase current system and converting the detected fault current into mechanical action for breaking the circuit includes circuitry for breaking the circuit in response to a selected secondary current substantially instantaneously rising to a predetermined level and a device for adjusting the predetermined level.

Abstract: A digital circuit interrupter having a keypad and display for entering and viewing the trip parameters utilizes a sampling algorithm to periodically sample the current within a protected circuit. The sampling algorithm allows a real time constant sampling interval independent of wide variations in the power system frequency.

Abstract: The circuit breaker comprises a thermistor located in a cold zone, near the front face of the trip device and at least one thermistor located in a hot zone, at the bottom of the circuit breaker case, in proximity to the circuit breaker connection terminals. The temperature difference measured between the hot and cold zones is representative of the temperature rise of the system protected by the circuit breaker and is used to modify the time delay of a delayed tripping function when the circuit breaker closes. The trip device can also take into account the temperature difference existing at the time of the previous trip.

Abstract: A circuit breaker includes a current detector for generator analog voltage signals in accordance with load current of respective phases and a control circuit for executing a tripping operation in response to the analog voltage signals. The control circuit includes an analog switch repeating a time division selecting operation that one of the analog phase voltage signals generated by the current detector is selectively allowed to pass through the same in a predetermined order, an analog-to-digital (A/D) converter for converting the analog voltage signal having passed through the analog switch to a corresponding digital signal, and a microcomputer receiving the digital voltage signal from the A/D converter and obtaining the effective load current value based on the digital voltage signals. The microcomputer generates a tripping order when the effective load current value exceeds a predetermined value.

Abstract: A fault-powered, processor-based circuit breaker tripping system employs a reliable low power trip indicator circuit that is normally powered from the tripping system. A liquid crystal display is used to indicate the status of the system, and a battery is used as a secondary power source after a trip terminates the power to the system. The battery is enabled by a manual switch or by a latch which responds to one of a plurality of trip signals from the processor. The latch also provides signals to a driver circuit to drive the LCD. Once enabled, the battery provides power to the latch and the LCD so that the cause of the trip may be displayed during a power fault. The manual switch can be used to select status signals to be displayed on the LCD, and to indicate the condition of the battery. The LCD includes a segment for indicating that the system is energized and power is being drawn from the current path but that amount of power is below all fault levels and insufficient to operate the system.

Abstract: In a prealarm circuit breaker which can issue a prealarm signal before occurrence of trip, a pair-transistor is employed in a charging circuit of a pair of capacitors, one of which serves to make a time delay after pickup of an overcurrent and the other of which serves to make a time delay pickup of a current of prealarm level.

Abstract: In a switch with pre-alarm means (101) having pre-alarming apparatus (20, 21) and an indicator (103) for alarming that value of current flowing on a load is above a predetermined alarming level, output of the pre-alarming apparatus is held at a predetermined level after the value of the current once becomes above the alarming level by self-holding function of thyristor (CR) even when the value of the current becomes below the alarming level after that.

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: A contactor includes two DC sensors within the housing which are isolated from the tripping unit, from the power supply and from each other by the combination of a transformer and photoelectric coupling, the sensed signals being pulse width modulated and demodulated on the respective sides of the photoelectric coupling barrier.

Abstract: So that internal faults (7) on high-voltage lines (4), generators (5), transformers (6) and other objects to be protected are more reliably detected even with saturated current transformers (3,8) and a tripping of protective measures such as, for example, an opening of switches (2,9) is reliably prevented in the case of external faults and short circuits (10), alternating current measurement signals (I.sub.1 ',I.sub.2 '), which are proportional to the alternating currents (I.sub.1, I.sub.2) flowing into the object to be protected, are detected by means of the current transformers (3,8). The alternating current measurement signals are then supplied via a low-pass filter (12), a transformer (13), a channel selection device (14), an analog/digital converter (15) to a microcomputer (16) for analysis. In the case of a fault, the microcomputer (16) provides a protective tripping signal (F=1) to switches (2,9) which open and thus isolate the object to be protected (4-6) from high-voltage lines (1,11).

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 digital circuit interrupter includes a microprocessor programmed for tailored overcurrent protection to power systems. A communication link permits the over-current set points to be selectively set within the microprocessor memory from a remote location. The over-current trip parameters are then derived by an algorithm which resides in the microprocessor memory.

Abstract: A visual indication system for easily providing information about the status of the output terminals of a solid state relay. A two-electrode neon glow lamp is connected across the output terminals of the relay in series with a current limiting resistor. The shunting impedance of the relay output terminals prevents voltage from inducing a glow in the neon lamp in certain modes of terminal configuration. When the terminals are ON, neither electrode glows. When the terminals are OFF, both electrodes glow. If the AC relay fails in a half-wave mode, only one of the electrodes will glow.

Abstract: Apparatus for detecting a primary fault current in a three-phase current system and converting the detected fault current in the mechanical action for breaking a circuit in which the primary fault current occurred includes a combination of transformers and diodes for receiving the three phases of current, providing corresponding phases of secondary current within a predetermined desired amperage metering range, choosing the largest magnitude secondary current and providing the largest magnitude secondary current as output, a resistor for providing voltage proportional to the largest magnitude secondary current, a capacitor for storing a peak value of the voltage which is proportional to the largest magnitude secondary current and a latching circuit for moving a trip member and providing mechanical action in response to the largest magnitude secondary current exceeding a predetermined level.

Abstract: A signal representative of the zero sequence current is obtained from current transformers associated with each phase and with the neutral if applicable by separate summing, in two distinct conductors, of the positive half-wave currents and of the absolute value of the negative half-wave currents produced by the set of current transformers, the difference between the currents flowing through these two conductors being representative of the zero sequence current.

Abstract: An add on ground fault detection system including a module readily connected to the distribution line and to the associated circuit breaker, and including circuit means for sensing a metering signal while providing a low resistance burden to summing transformers, and providing a relay tripping signal if the metering signal is above a selected level.

Abstract: An electronic trip unit within a self-contained circuit interrupter utilizes dual electromagnetic trip actuators. One such actuator responds to overcurrent conditions to interrupt the protected circuit up to a predetermined value. The other such actuator interrupts the protected circuit at all overcurrent conditions in excess of the predetermined value.

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: 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 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: A power bus fault detector for detecting faults in a predefined portion of an electrical power bus having at least one phase. Power feed lines are coupled to the predefined portion of the power bus by circuit breakers. Current transformers are used to detect the current flowing through each phase of each power feed line which is coupled to the predefined portion of the power bus. A summer generates a current differential signal for each phase that is equal to the sum of the currents detected by the current transformers. A fault detector generates a trip signal which causes the feed line circuit breakers to disconnect the feed lines from the power bus when a fault is detected in the predefined portion of the power bus. The fault detector includes a detector which detects when the current differential signal in any of the power bus's phases is substantially nonsinusoidal in shape.

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: A regulator includes a switching transformer (TR) whose primary winding is divided into two halves through which current flows alternatingly via one respective switching transistor (Q1, Q2). The pulses on the secondary side of the transformer are rectified to attain the output voltage. The output voltage is controlled by pulse width modulated driver pulses for the two switching transistors. A protective circuit (12) with immediate effect terminates the currently applied driver pulse when the current flowing through the conductive switching transistor reaches a critical current value. A protective circuit (14) with delay effect prevents the generation of further driver pulses upon a further increased overload, this prevention being limited with respect to time. The protective system directly is controlled by the primary current of the power regulator.

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 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.