Abstract: A method and a device are for power supply switchover in a power system, including two power supplies, each being connected to a bus through an incoming line. The power supply currently in operation is used as the main power supply and the other power supply is used as a backup power supply. Both the incoming line and the bus have three phases, and the lines are connected by their phases. In an embodiment, the method includes: determining whether there is at least one sound phase among the three phases after identifying a fault in the power system; and if there is, obtaining a power data on the sound phase before the main power supply is disconnected. The power data is usable to determine whether the backup power supply meets the condition for connecting in the quick mode after the main power supply is disconnected.

Abstract: Disclosed are an overcurrent protection method, a display panel and a display device. The overcurrent protection method is applied to the display panel. The display panel includes a power supply circuit, a timing controller, a level shifting circuit and a gate driving circuit. The overcurrent protection method includes: in response to the level shifting circuit outputting a start clock signal to the gate driving circuit, timing, by the timing controller, and obtaining an input current average value input by the power supply circuit to the level shifting circuit during a first timing period t0 to t1; and controlling the gate driving circuit to enter an overcurrent protection state, in response to the input current average value being greater than or equal to a preset current average value.

Abstract: Systems and methods are described for preventing damage from overcurrent flows in a display device. The display device may include a display panel, a display panel driving circuit, and a driving control circuit. The display device also includes, a power management integrated circuit and a display panel protection circuit. If an overcurrent condition is detected, the display panel protection circuit may periodically mask frames from being sent to the display panel to prevent damage.

Abstract: A display device includes a display panel including a plurality of pixels, a controller which generates a gate reference signal, a gate control circuit which outputs a gate driving signal based on the gate reference signal, and a gate driving circuit which provides gate signals to the plurality of pixels based on the gate driving signal. The gate control circuit includes a protection enable circuit which detects a first period of the gate reference signal, determines whether the period of the gate reference signal is changed, and generates a protection enable signal when the first period of the gate reference signal is not changed, and an over-current protection circuit which generates an over-current occurrence signal by detecting an over-current of the gate driving signal, and stops outputting the gate driving signal based on the over-current occurrence signal and the protection enable signal.

Abstract: A circuit including over-current protection includes a voltage input, first and second switching transistors that are complementarily switched and that receive current from the voltage input, a first resistor, a first diode including a first anode and a first cathode, and a second diode including a second anode and a second cathode. The first anode and the second anode are connected to each other and are connected to the voltage input via the first resistor. The first cathode is connected to the first switching transistor and the second cathode is connected to the second switching transistor such that the connection of the first and second anodes provides an over-current signal that is related to the current in the first and second switching transistors.

Abstract: A protection relay is disclosed that generates a trip signal to operate a circuit breaker in case of a fault condition. A first module provides measurement and analysis of power parameters of the power line connecting the power equipment that is being protected, the protection being provided by generating a first trip signal for operating a circuit breaker connected in the power line. One or more second modules can boost performance of the protection relay by measurement and analysis of power parameters-to generate a second trip signal for operating a circuit breaker connected in the power line. The first trip signal and the second trip signal are logically combined to generate a trip signal that operates the circuit breaker.

Abstract: A controller configured to detect fault conditions in a circuit that operates an electrical-load includes a gate-driver and a voltage-detector. The gate-driver is configured to control a gate-current to a switching-device. The gate-current is controlled such that the switching-device is operated in a linear-state when the switching-device transitions from an on-state to an off-state. The voltage-detector is configured to determine a voltage-drop across the switching-device. The controller is configured to indicate a no-fault condition when the voltage-drop is greater than a voltage-threshold for more time than a no-fault interval after the switching device is operated from the on-state to the linear-state.

Abstract: A circuit breaker trip unit includes an input section receiving a phase current level signal. A processor is in communication with the input section and generates a first trip signal based on the phase current level signal and user-adjustable trip settings. The trip settings include long time and short time pickup and delay settings. An analog instantaneous trip circuit is in communication with both of the input section and the processor. The analog instantaneous trip circuit includes a digital potentiometer having a non-volatile memory. The potentiometer provides a reference signal corresponding to a resistance setting stored in the memory. The analog instantaneous trip circuit compares the phase current level and reference signals, and generates a second trip signal based on a result of the comparing. The processor programs the resistance setting stored in the memory according to a user-adjustable instantaneous current pickup setting.

Abstract: The circuit monitoring device is disclosed. The device is for monitoring circuit resistance. At configurable thresholds digital flags are triggered, the device can be used as a Security/Building management system. The device uses open technology is fully scaleable and allows programmable logic controllers to be used as security management systems. Using a soft logic option a PC could take the place of the PLC.

Abstract: A circuit protection system has a normal mode, and a maintenance mode with reduced potential arc flash energy. A downstream circuit breaker is mounted within a first enclosure comprising a first access panel. A locking mechanism locks the first access panel closed. An upstream breaker is mounted within a second enclosure comprising a second access panel. A current sensor senses current and is in communication with an electronic trip unit that controls current interruptions by the upstream breaker based on a trip setting. A user interface device is accessible when second enclosure is closed, and allows user selections of normal and maintenance modes. When maintenance mode is selected, the trip unit changes the trip setting such that potential arc flash energy is reduced. The system is configured to keep the first access panel locked closed based on normal mode being selected, and allow unlocking based on maintenance mode being selected.

Abstract: The present invention is directed to an electrical wiring device that includes a frameless shutter assembly disposed in the front cover portion or in a separator member between the receptacle openings and the receptacle terminals. The frameless shutter assembly comprises a first shutter member and a second shutter member configured to move from a closed position to an open position when the hot and neutral blades of a plug blade set are simultaneously inserted into the receptacle openings to engage a set of receptacle terminals and remain closed otherwise. The front cover member and/or the at least one separator includes a first stop member disposed proximate the first shutter member and a second stop member being disposed proximate the second shutter member.

Abstract: A driver circuit includes: a first transistor connected between a line of first voltage and an output terminal; a first overcurrent detector configured to output a first signal when overcurrent flows into the first transistor; a first control unit configured to turn on and off the first transistor at a predetermined period and turn off the first transistor when the first signal is output from the first overcurrent detector; and a counter configured to count the number of times by which the first signal is output from the first overcurrent detector within a predetermined time interval, and to output a shut-down signal to stop an operation of the driver circuit as a value of the count reaches a predetermined value of equal to or more than 2.

Abstract: Circuits and methods for overcurrent fault detection using a debounce timer to qualify the presence of an overcurrent fault based on an overcurrent signal being asserted for at least a predetermined time interval. The debounce timer may be used in conjunction with state-qualified fault sensing and/or blank-time-qualified fault sensing.

Abstract: Methods and techniques to implement a digital signal processor for avoidance of audio feedback are disclosed, in particular, audio signal processing systems that reduce the requirement for physical segregation of sound acquisition and diffusion zones. In a more general aspect, the components and techniques described herein provide a for a sound space and sound processing equipment such that sound travelling electronically in a loop through the sound processing equipment that is output into a physical sound diffusion zone, received at the input to the sound processing equipment, and then re-amplified, etc. is attenuated over that loop by frequency modification. The frequency modification is such that, at least for some signals, on each pass through the loop, the sound processing equipment will attenuate or amplify individual sub-bands of the frequency spectrum of the audio signal that is received at the input of the sound processing equipment.

Abstract: A latch-control protection circuit applied in a power converter is provided. The protection circuit has a comparing circuit unit and a logic gate. The comparing circuit unit is utilized to selectively output a default signal or a comparing signal according to a state signal from the logic gate, wherein the default signal is utilized for latching the state signal and the comparing signal is corresponded to the power condition of the power converter. The logic gate generates the state signal according to the output signal of the comparing circuit unit and a system judging signal. The output signal may be the default signal or the comparing signal. The system judging signal indicates the condition of the power converter.

Abstract: A power supply (200) is provided having a plurality of independent current limiting circuits. A first current limiting circuit (6) provides protection against a short circuit or other extraneous load conditions, while a second current limiting circuit, using a trace on a PCB as a sensing element, is programmable on the basis of a time constant and a current level.

Abstract: A method and system to protect a circuit having at least a first circuit breaker, and a second circuit breaker arranged directly upstream of said first circuit breaker, said first circuit breaker having configuration settings selectable between a normal mode and an alternate mode, the alternate mode setting including a reduced energy let-thru (RELT) mode setting having a RELT mode trip time delay, by determining if said first circuit breaker is configured in said RELT mode, determining a dynamic delay time for opening said second circuit breaker, wherein said dynamic delay time is based at least in part on said RELT mode trip time delay of said first circuit breaker, and triggering said second circuit breaker to open after said dynamic delay time has elapsed.

Abstract: An induction motor drive includes a plurality of inverters, a changeover switch which changes over outputs of the plurality of inverters to be supplied to one induction motor and a changeover controller which controls the changeover switch on the basis of a failure detection signal of one inverter to change over from the one inverter to another inverter to start the other inverter so that the induction motor is driven. The changeover controller includes a frequency/phase detector which always detects a frequency and a phase of a terminal voltage of the induction motor and a starting frequency/phase setting device which controls a frequency and a phase at starting of the other inverter in accordance with detected values of the frequency/phase detector when the failure signal is inputted.

Abstract: The present invention is directed to an electrical wiring device that includes a cover assembly is coupled to the housing. The cover assembly includes at least one set of receptacle openings disposed on either side of a central portion of the cover assembly in communication with a portion of the plurality of receptacle terminals. A fault detection circuit is configured to provide a fault detection output in response to detecting a fault condition. A circuit interrupter is coupled between the plurality of line terminals and the plurality of load terminals. A light assembly is coupled to the plurality of line terminals or the plurality of load terminals. The light assembly has a light transmission region disposed in the central portion and occupying a substantial portion of a width of the cover assembly. The light assembly is selectively driven from a de-energizeci state to a light emitting state in response to a predetermined stimulus.

Abstract: The invention relates to power cable comprising, at least one HTS-tape and a cooling system comprising a fluid cooling medium for cooling the at least one HTS-tape. The at least one HTS-tape being at least partly surrounded by a cooling layer comprising said fluid cooling medium and an electrical insulation at least partly impregnated with said fluid medium. The power cable of the invention has shown to reduce the risk of fault current and electrically breakdown. When extra cooling is needed for stable operation the cooling medium may evaporate in the cooling layer for providing the cooling.

Abstract: A protection device for an oscillating power circuit, namely for a demining coil, such device incorporating circuit breaking means positioned between an alternating current supply network and the power circuit, such device wherein it comprises at least one means to measure and analyze the current supplying the power circuit, means able to detect the appearance of a direct current and connected to triggering means ensuring the opening of the circuit breaking means when the alternating current ceases.

Abstract: A trip unit includes a housing having a first opening and a second opening. A sensor senses a current flowing in an electrical circuit and provides a signal representative of the current. A selector switch is disposed proximate the first opening and selects one of predetermined instantaneous current conditions and predetermined arc reduction maintenance system current conditions. A movable indicator cooperates with the selector switch, is disposed proximate the second opening, and indicates whether one of the predetermined instantaneous current conditions or one of the predetermined arc reduction maintenance system current conditions is selected by the selector switch. A trip mechanism cooperates with the sensor and the selector switch to evaluate the signal representative of the current with respect to the selected one of the predetermined instantaneous current conditions and the predetermined arc reduction maintenance system current conditions, and responsively generates a trip signal.

Abstract: A method of protecting an electromechanical power transfer system from excessive peak electrical potentials, the power transfer system comprising a prime mover, a dynamoelectric machine coupled to the prime mover for generating multiphase alternating current (AC) power, and at least one multiphase AC electrical load coupled to the dynamoelectric machine by way of a multiphase AC power bus, the dynamoelectric machine having a control coil responsive to control current for varying power supplied to the electrical load, comprises the steps of: analysing electrical potentials on the power bus to generate analysed power bus characteristics; comparing the analysed power bus characteristics to predetermined power bus characteristics; simultaneously shunting power across the power bus and reducing control current to the control coil for the dynamoelectric machine when the analysed power bus characteristics approximate the predetermined power bus characteristics to reduce the measured electrical potentials; and simult

Abstract: An enclosure for compact computer boards is described that allows a user to easily configure, or reconfigure, a microserver stack using an interchangeable common bus as a data and power backbone. One application requiring robust and rigorous design constraints is use within an aircraft.

Abstract: A method and an apparatus are disclosed for disconnection of a fault current which has occurred in an AC power supply system. A disconnection command which is produced in a protective device is supplied to a synchronization controller in order to open a circuit breaker, in which synchronization controller a command is delayed until the circuit breaker can be opened in synchronism with the power supply system. The method includes monitoring of the disconnection command emitted from the protective device and monitoring a fault-current signal, or a status signal emitted from the circuit breaker, and formation of an emergency disconnection command if the fault-current signal or the status signal is still present following a delay time after emission of the disconnection command, which delay time is greater than a sum of a natural response time of the circuit breaker and a time for quenching of a switching arc produced on opening of the circuit breaker.

Abstract: A distributed monitoring and protection system for a distributed power network. The system includes a plurality of high-speed measuring units (MUs), wherein each MU is coupled to a power line to measure values of electrical parameters of the power line. Electrical parameters, such as current, voltage, power and frequency are measured by the MUs. The MUs communicate with a control unit (CU) over a high-speed communications network. The CU includes a processor executing algorithms for evaluating the measured parameters to determine the status of the power network and the MUs. The processor also executes fault detection and isolation by comparing the measured values against predetermined threshold values. When a fault is detected by the CU, protective action, such as tripping of a circuit breaker, may be initiated by the CU directly or by transmitting the tripping command over the high speed data network to a local MU. The local MU may then trip the circuit breaker.

Abstract: The instantaneous tripping threshold of the selective tripping device is a decreasing function of a quantity representative of the time necessary for the current to reach the peak value. The variation curve is disposed between first and second curves, obtained experimentally, representative of envelopes of the peak current values. The first curve is obtained when the circuit breaker associated to the selective tripping device is alone and the second curve when it is connected in series with another circuit breaker connected down-line.

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: An integrated circuit breaker is described having shunt trip capability along with automatic overcurrent protection. The shunt trip unit provides auxiliary power to the trip unit and allows the trip unit to report and record the shunt trip operation. A control circuit determines whether there is sufficient operating power available as well as the condition of the circuit breaker contacts prior to executing the shunt trip operation.

Abstract: A relay control circuit in which a capacitor is used as a power source of a transistor which prohibits operation of the transistor which is operated by input by switch operation. If power is no longer supplied to the entire relay control circuit while the capacitor is discharging, switch input is prohibited.

Abstract: An electrical generator system integrated controller device utilizing PID control and capable of regulating voltage or current, and frequency simultaneously. The device utilizes a micro-controller (30.1) to monitor the engine generator set (20), then determines the appropriate signal to deliver to the electrical generator set (20) to regulate the engine throttle (21) and the generator (22) field windings. The micro-controller (30.1) also provides for real and reactive load sharing with additional generator sets (40) while also providing for an integrated circuit interrupter module (500) to open the line from the generator (22) to the load bus (42). Additionally, serial communications (34) are provided as well as displays (35), meters (37), and operator input (36). Finally, the permissive paralleling module (700) provides that the engine electrical generator set (20) will not be allowed to be connected to the load bus (42) until standards of voltage and phase have been achieved for a set period of time.

Abstract: The disclosed fault indicator which senses current in a cable, resets in response to a minimum current and arms a trip arrangement in response to current rising a predetermined amount with respect to time. If the rising current also opens a circuit breaker within a predetermined time and cuts off current to the cable, the indicator trips. If no zero current occurs within the time period, the trip arrangement is disarmed for the next current rise.

Abstract: A circuit breaker bandwidth limits a sensed rate of change of current, di/dt, in the neutral conductor of a protected electrical system and fullwave rectifies the bandwidth limited di/dt signal for comparison with an instantaneous trip reference signal. The bandwidth is selected to provide a selected relative sensitivity of the instantaneous trip to sinusoidal currents associated with overcurrent faults and step currents associated with sputtering arc faults. The rectified bandwidth limited di/dt signal is also filtered and delayed for comparison with a delayed trip reference signal. The time constant for the filter is selected to provide a selected relative sensitivity of the delayed trip to overcurrent faults and sputtering arc faults. A low mu sensing coil used to generate the di/dt signal can also serve as the neutral current sensing coil of a dormant oscillator ground fault protection system.

Abstract: A sensitive and fast low voltage lamp system controller to provide safe operation of "bare wire" systems that are particularly attractive for use in exhibition and tradeshow booth lighting. The high sensitivity is achieved by emphasizing high frequency noise present during shorts and by proportionately limiting the instantaneous current that tracks the line AC voltage waveform; fast response is provided by a power FET coupled to a bridge rectifier in series with the load and both then in series with a protection relay.

Abstract: A time delay and alarm system is provided to ensure safe operation of periodically activated apparatus having potentially dangerous moving parts. The system preferably employs a 555 type integrated timer circuit, a horn, and a pulse generator which causes the horn to produce a cyclical sound.

Abstract: A fault indicator which senses current in a cable, resets in response to a minimum current and arms a trip arrangement in response to current rising a predetermined amount with respect to time. If the rising current also opens a circuit breaker within a predetermined time and cuts off current to the cable, the indicator trips. If no zero current occurs within the time period, the trip arrangement is disarmed for the next current rise.

Abstract: A squaring circuit and an i.sup.2 t circuit utilizing the squaring circuit. The squaring circuit comprises a voltage-controlled oscillator and a frequency/current converter which are connected to one another, with the input voltage signal being supplied to the voltage-controlled oscillator and to the frequency/current converter on the one hand, and with the output voltage signal being tappable at an RC network connected to the output of the frequency/current converter on the other hand. The value of the output voltage is proportional to the square of the value of the input voltage. With this squaring circuit, it is possible to construct an i.sup.2 t protective circuit for protection of an electrical consumer from overload.

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: 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: In a system-powered solid-state trip device, the measurement voltage Vm, representative of the current flowing in the conductor to be protected and applied to the input of an electronic processing unit, can also be applied to the cathode of a thyristor connected in series with the trip coil and receiving on its gate, the tripping orders from the processing unit. A Zener diode is connected between the thyristor gate and the ground so as to set an instantaneous tripping pick-up of the trip device. In this way, a short-circuit in the conductor causes instantaneous tripping of the circuit breaker independently from the value of the supply voltage.

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: A two-wire telephone subscriber line protection arrangement consists of two protection devices each comprising a pair of complementary thyristors connected in reverse parallel with one another between a respective wire and a reference point, with their gates connected together and directly to a control terminal which has a connection to the wire via a resistance which determines an overcurrent threshold level for the device. The reference point is ground for the ring wire protection device, and is desirably the ring wire for the tip wire protection device, whereby a directional sensitivity of the protection devices is taken advantage of and the overcurrent threshold level can be reduced. Zener diodes connected between complementary thyristors provide for convenient overvoltage protection.

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: A power interrupter for non-destructively protecting for instance 120 Vac equipment test when that equipment is likely (i.e., expected or designed) to develop a short circuit across the ac power line. The speed of response (50-microsecond turn-off) is significantly faster than that of ordinary line circuit breakers or fuses, both of which react in milliseconds. The device can be applied to any circuit protection problem where speed of response is crucial.

Abstract: An overcurrent protection system (10) for a power supply is disclosed. The system monitors the instantaneous flow of current between a power supply (12) and an electrical load (16) to detect when the flow of current exceeds a maximum rated amount. A counter (30) is used for counting the number of times that samples of the flow of current exceed the maximum rated amount synchronous with zero current crossing to generate a trip signal when a predetermined count is reached which disconnects the power supply (12) from the load. The counter (30) is decremented each time a predetermined time interval elapses in which the flow of current above the maximum rate is not detected as measured from a point of zero current flow between the power supply (12) and the electrical load (14). The invention may be used for both AC and DC power supplies.

Abstract: The apparatus relates to an excess-current monitoring device in a direct-current generator having a controlled rectifier, and is particularly useful for electro-chemical machining. A reference signal is generated by a signal generator in accordance with the voltage drive of the rectifier and the mean current supplied to the load. The reference signal is supplied to a comparator which supplies a current-switch-off-signal when the value of the reference signal as compared to the instantaneous load current indicates excess mean load current. This enables optimum machining.

Abstract: A transformer differential relay which includes apparatus for speeding up the detection of a power transformer internal fault condition to initiate breaker action which interrupts current through the transformer is disclosed. Presently, conventional transformer differential relays include a unit for each phase of the power transformer for detecting a potential internal fault in a respective transformer phase winding and for generating a signal to operate a set of breakers. This breaker operation is inhibited for current inrush conditions of the transformer. However, a processing time is associated with the detection of such a current inrush condition. Accordingly, the breaker operating signal must be delayed for at least this processing time in order for the inhibition to be effectuated. For the case in which there is no current inrush condition, the breakers remain delayed in operation from the inception of a true internal fault.

Abstract: The invention consists in using current transformers incorporated in the electronic relays of a switchboard protective device and in connecting thereto current measurement indicators located on the front face of the switchboard.

Abstract: An electrical circuit to signal a circuit breaker to trip when the circuit breaker is closed and a high level fault occurs or when a low level fault occurs while the breaker is in the process of closing. A mechanical switch tied to the breaker contacts deactivates the low level trip function when the contacts are closed. A high level overcurrent causes a trigger diode to conduct current, energizing an opto-coupler that causes the trip solenoid to trip the breaker. The circuit also causes the breaker to trip if a sustained medium level overcurrent exists.