111 results about "Overcurrent relay" patented technology

The invention discloses a detection method of an inverter grid-connected alternating-current relay. The first end of the alternating-current relay is connected with the output end of an inverter; thesecond end of the alternating-current relay is connected with an alternating-current grid; when the alternating-current relay is detected, a first voltage difference between the first end and second end of the alternating-current relay is detected at first; when it is judged that the absolute value of the first voltage difference is smaller than a first threshold value, the direct-current bus-barneutral point voltage to earth of an inverter input end is changed; a second voltage difference between the first end and second end of the alternating-current relay is detected again; and if the absolute value of the second voltage difference is smaller than a second threshold value, it can be determined that an adhesion fault occurs on the alternating-current relay. With the method adopted, theshort circuit to earth of a certain phase of a live line, the inconsistency of the earth impedance of a three-phase power grid, or other conditions can be prevented, and the accuracy of the detectionof the adhesion failure of the alternating-current relay can be improved.

The invention discloses a test method of simultaneously simulating system failure and channel abnormal to a fibre channel protector. The method comprises the following steps: a power system real-time digital simulation system is used to control when a system failure occurs, after the occurrence of the failure, a current power amplifier outputs failure current, an overcurrent relay is accessed, the overcurrent relay acts in the action delay set by a time relay, and the closure of secondary contact is triggered, an error code generator is started so that various abnormal actions of the channel can be added in the error code generator after the system failure, wherein the abnormal actions contain channel interrupt, superposition of error code, superposition of time delay, superposition of error code and time delay, and the like. The method can simulate power system failure while reliably controlling various abnormal actions of the fibre channel.

The invention relates to a fault indicator and distributed intelligent terminal matched overhead distribution network fault positioning method, and belongs to the technical field of relay protection of power systems. On the premise that overcurrent relay protection of a traditional distribution network is not changed, distributed intelligent terminals are installed on circuit breakers at all trunk section points and fault indicators are installed on all branch circuits, the installation positions of the distributed intelligent terminals are taken as nodes, a relation between the fault indicators and the nodes is defined according to the positions of the nodes and the fault indicators, and trunk units and branch units are divided and numbered to form a unit adjacency list. When faults occur, an automatic reclosing lock recloses transient faults, the distributed intelligent terminals isolate permanent faults, and meanwhile, the distributed intelligent terminals and the fault indicators detect current values and compare maximum branch current values in the relevant unit adjacency list to position trunk faults and branch faults.

The invention discloses a distribution network overcurrent protection method with a distributed power supply, and a fixed value optimization method and system, and belongs to the technical field of distribution network relay protection. When a fault occurs, a data acquisition system acquires a fault current flowing through each inverse time limit overcurrent relay in the distribution network witha distributed power supply; according to the inherent characteristics of the fault current and the inverse time limit overcurrent relay and the selectivity, the sensitivity and reliability requirements of the relay protection, a mathematical model is established, wherein the mathematical model comprises an objective function and a constraint condition; a particle swarm optimization based on crowdsearch is employed to perform particle optimizing of the time setting coefficient and starting current of the inverse time limit overcurrent relays; and according to the optimal particles, the time setting coefficient and starting current of each inverse time limit overcurrent relay are subjected to re-assigning, and faults are cut off in the shortest time. The problem is solved that the relay fixed value is improperly set after the distributed power supply is accessed into the distribution network.

A system, method, and device for protecting an induction motor are disclosed. The exemplary system may have a module for determining the current drawn by the motor and a module for determining the state of the motor. The system may calculate a used thermal capacity based on a first formula when the motor is in an active state. The system also calculates the used thermal capacity based on a second formula when the motor is in an inactive state. When the used thermal capacity attains a threshold, the relay is tripped thus removing current to the motor and preventing motor from overheating. A method to derive thermal time constants from desired trip time limits (such as those defined by IEC standards or the thermal limit curves provided by motor manufacturers) is also presented. For example, the thermal time constants can then be used in tacking motor used thermal capacity throughout various motor states.

A control method for preventing malfunction of an over current ground relay is disclosed. The control method includes: determining directions of per-phase power flows by measuring the magnitudes and phases of per-phase voltages and currents in an electric power system; checking occurrence of a load fault or a power source fault using the determined directions of per-phase power flows; and controlling an over current ground relay (OCGR) or an over current relay (OCR) to transmit a trip signal to a circuit breaker, after, upon occurrence of a load fault, checking occurrence of a ground fault and checking occurrence of a short circuit fault, and, upon occurrence of a power source fault, checking occurrence of a short circuit fault without checking occurrence of a ground fault, by turning on or off the OCGR or the OCR according to occurrence of a ground fault or a short circuit fault.

The invention discloses a control method and a system of an intelligent threaded rod juicer, wherein the control system of the intelligent threaded rod juicer comprises a power supply wire, a host machine, a motor, a control system, an extracting device and a switch, wherein the control system is arranged in the host machine; and the host machine is provided with a control panel. The control system of the intelligent threaded rod juicer is characterized in that the control panel is provided with juicing buttons aiming at different food materials; the buttons are matched with the control system; each button is corresponding to different motor rotation speeds or rotation speed variation modes; the control system feeds back information with overhigh load to a controller through a current detection and feedback effect, thus the motor is controlled to rotate reversely intermittently, thus the food materials in the juicing device are loose, and the effect of load reduction is achieved. The information with overhigh load is fedback through a current relay, thus the motor is controlled to rotate reversely intermittently, thus the food materials are loose, and the load is reduced, thus the motor is protected; and meanwhile, through the control of a rotation speed control module, the speed of different foods of the motor is realized, the whipping efficacy is improved, and the control system of the intelligent threaded rod juicer is convenient and safe to operate, has long service life, and improves the juicing effect and juice yield of each kind of food material.

An overcurrent relay able to detect a failure current and rapidly generate a driving signal to drive a circuit breaker in response to the failure current is disclosed. The overcurrent relay has at least one Hall sensor detecting a failure current and outputting a Hall voltage signal; a filter filtering the Hall voltage signal to output a filtered signal having only an exponent wave; a reference voltage provider providing a reference voltage; a comparator comparing the filtered signal with the reference voltage and outputting a trigger signal when the filtered signal reaches the reference voltage; and a circuit breaker driver being triggered by the trigger signal to output a driving signal for driving a circuit breaker.

The invention discloses a testing device for alternating-current relays and a testing method thereof. The testing device consists of a power switch, an ampere meter, a voltmeter, a transformer, a voltage regulator, the alternating-current relays, a high-power resistor and output indicator lamps. The testing device provides a function testing platform for detecting the alternating-current relays and the testing method. The mechanism of the testing device is that the working state of the alternating-current relays in a whole circuit is simulated, high-power load is adopted to test the bearing capability and the dynamic working performance of the alternating-current relays under the conduction state, electricity is obtained by utilizing a relay KA coil, and the state of two groups of normally closed contacts changes so as to achieve state convention. If the state convention is not achieved, or the indicator lamp are turned on or turned off simultaneously or are inoperative completely and other situations, the alternating-current relays are defective products and unqualified products. Therefore, the unqualified products are selected out. The circuit can test ten alternating-current relays in one time.

A current transformer capable of switching transformation ratios for metering off-grid energy of wind power plants belongs to the technical field of wind power plant metering transformers and facilitates metering of the off-grid energy of wind power plants. According to the technical scheme, the current transformer capable of switching transformation ratios for metering the off-grid energy of wind power plants comprises a first winding circuit and a second winding circuit, wherein the second winding circuit comprises a signal actuating circuit, a signal acquisition circuit, a signal converting circuit and an overload protecting circuit, the second winding circuit comprises intermediate relays of ZJ1, ZJ2 an ZJ3, an overcurrent relay LJ1, an inverse power relay NGJ1, an outage delay time relay SJ1, an electrifying delay time relay SJ2, an electrifying delay time relay SJ3, a protection stop button SB1 and a bell D1. The current transformer capable of switching transformation ratios for metering the off-grid energy of wind power plants is suitable for an electric power sector.

There is provided an overcurrent protection device configured to protect a load from an overcurrent. A first overcurrent detector configured to detect the overcurrent, based on a value of a current flowing through the load, time for which the current flows through the load, and an overcurrent cutoff characteristic upon non-operation of the load. An overcurrent breaker that cuts off the overcurrent to the load when the first overcurrent detector detects the overcurrent.

A ground rail tram control system comprises a ground rail, a tram, a drive motor, a power supply circuit, a power control circuit, a flat vehicle power supply circuit and a flat vehicle control circuit. The power supply circuit is connected between commercial power and the ground rail, the power control circuit is connected to the power supply circuit in parallel, an overcurrent relay is arrangedin the power control circuit, a normally-closed contact of the overcurrent relay is connected with the power supply circuit in series, a coil of the overcurrent relay is further connected with the low-voltage output end of a step-down transformer in series, the flat vehicle power supply circuit is connected between the ground rail and the drive motor, and the flat vehicle control circuit is connected to the flat vehicle power supply circuit in front of the drive motor in parallel. By the adoption of the control system, an overcurrent protection device is erected on the low-voltage side of thestep-down transformer of the ground rail where the tram runs, the situation that the transformer is burnt out due to overcurrent is avoided, so that the maintenance cost of equipment is reduced, and the situation that production efficiency is low due to equipment faults is avoided as well.

A high-frequency heater ensures a constant breaking current, maximizes input current, and thus produces a maximum high-frequency output efficiently. In this high-frequency heater, a power supply (1) is connected in a supply line associated with an overcurrent relay (4a), and a power converter (2) converts the power from the power supply (1) to high-frequency power and supplies it to a magnetron (15). A control circuit (20) supplies a signal to an inverter controller (10) to control input current so that the input current characteristic of the high-frequency heater may become close to the current breaking characteristic with time of the overcurrent relay (4a).

The invention relates to the field of motor control, in particular to a motor safety control circuit system. The motor safety control circuit system comprises a protection circuit, a communication circuit system and a switch circuit, wherein the control circuit can be used for generating a four-phase control signal, can be applied to two-phase double-pole and four-phase single-pole stepping motors controlled by a computer, and can be used for controlling the stepping motors in single four-step, double four-step and four-phase eight-step ways; a PWM (Pulse-Width Modulation) chopper circuit in a chip can be used for adjusting current of a motor winding in a stepping motor winding in a switching mode; a fuser FU is applied to short-circuit protection; overcurrent relays KI1 and KI2 are applied to overcurrent protection; an under-voltage relay KUD is applied to under-voltage protection of a main circuit; a thermal relay FR is applied to overload protection; a normally open contact KUD (1-3) of a zero-voltage relay KUD and a contact QM0 of a master switch QM construct a zero-position self-locking link; a positive contactor KM1 and a negative contactor KM2 construct an interlocking link. The motor safety control circuit system is convenient to operate, has higher safety, can be used for realizing remote control, and has very high creativity.

The invention relates to a control system of a dual-drive electric automobile. A main controller controls a main motor to use. The coil of an overcurrent relay is serially connected in the power supply line of the main motor. The main motor and an auxiliary motor respectively output power to a rear axle through two electric automobile bidirectional sliders. The movable contact switch of the overcurrent relay is serially connected between the signal output end of an accelerator and the signal input end of an auxiliary controller. The signal input end of the accelerator is connected with the signal output end of the main controller. A vehicle-mounted power supply respectively supplies power to the main controller and the auxiliary controller. By using the overcurrent relay, not only can the running speed of the electric automobile be guaranteed, but also the energy consumption during constant-speed running is reduced and the running mileage is elongated; by using the bidirectional sliders, the goal of transmitting the power to the rear axle to drive the electric automobile to run no matter that the motors rotate forwards or backwards; and since balls are not in contact with outer rings, the friction resistance is reduced, the sliding distance of the electric automobile is longer and the running mileage is elongated.

The invention discloses a ship electric energy distribution control device based on contacts and a control method. The ship electric energy distribution control device mainly comprises a first contact, a second contact, a third contact, a fourth contact, an over-current relay, a first on-delay relay, a second on-delay relay and a third on-delay relay, wherein the components are correspondingly connected to form a main circuit and a control circuit of a ship power generator set. The ship electric energy distribution control device is simple in structure and low in cost. According to the control method, when the generation capacity of the ship power generator set is reduced, the control circuit of the ship power generator set enables corresponding contact coils to be electrified in sequence according to the importance degrees of loads, three types of loads can be started in the descending order of the importance degrees of the loads, at the same time, an over-current signal in the main circuit can be detected through the coil of the over-current relay, coils of corresponding contacts in the control circuit are subject to power loss, main contact heads of corresponding contacts of the main circuit can be turned into a normally opened state from a normally closed state, and corresponding loads can be cut off, so that reliable operation of important loads can be ensured.

The invention relates to equipment for searching a ground fault point of a generator stator winding bar. The equipment comprises a regulation circuit and a detector; the inside of the regulation circuit is connected with a current relay; and by the current relay, a current accessing the regulation circuit does not exceed 5A, so that reoccurrence of a short circuit burn of a generator stator iron core is effectively avoided. According to the method using the equipment, a voltage is applied to a fault phase of the generator stator winding bar, the current reaches the ground through the ground fault point of the stator winding bar and is returned to a ground terminal (i.e., a ground end applying the voltage) of the regulation circuit to form a loop, and no current flows between an end which is not applied with the voltage and the fault point. The detector measures the current of the ground fault phase (the winding bar) of a generator stator, and when a measured value of an ammeter of thedetector is suddenly changed and for example, the current is suddenly changed into 0 or nearly 0 from a high value, the ground fault point is positioned at a current sudden change position, so that the ground fault point of the generator stator winding bar can be accurately and rapidly found and the precondition is provided for accurately and rapidly processing such type of fault.

The invention provides a device for adjusting the wall thickness of a hot rolled steel tube and relates to a wall thickness adjusting device. The device comprises an electric control device and a hydraulic device controlled by the electric control device, wherein the electric control device comprises a current transformer arranged on a main motor of a rolling mill, an overcurrent relay, a time relay and an auxiliary relay; and the hydraulic device comprises a change valve and an oil cylinder. The current transformer, after being electrified, drives the overcurrent relay and the auxiliary relay to close; a control circuit is kept to normally work through an auxiliary latching contact of the auxiliary relay; and the time relay controls the working state of the change valve by controlling the auxiliary contact of the auxiliary relay. The device of the invention has the advantages of effectively reducing even eliminating uneven longitudinal wall thickness of the hot rolled steel tube, improving the quality and the yield of the steel tube, along with simple structure, easy manufacturing and control, low investment and high profit.

The invention relates to a method for the tandem operation of an alternating current shunt release and an alternating current relay. The method comprises the following steps that: when a button switch connected in parallel with the intermediate alternating current relay is turned on, a sampling circuit samples one-way pulsating direct current voltage generated by a rectifier circuit, and a micro controller unit (MCU) circuit acquires sampling voltage Vsa and a zero-crossing pulse signal SI obtained by the sampling circuit, and judges whether the one-way pulsating direct current voltage reaches 60 percent of a rated voltage value Ue for the operation of a shunt electromagnet coil or not; and if the one-way pulsating direct current voltage reaches 60 percent of the rated voltage value Ue for the operation of the shunt electromagnet coil, the MCU circuit outputs a control signal to turn off a high-load circuit to quickly increase a value of the one-way pulsating direct current voltage, and generates a single pulse signal with the duration of 50 to 60ms in the zero-crossing of the one-way pulsating direct current voltage, and the single pulse signal controls the electrical conduction of the shunt electromagnet coil after being amplified by a driving circuit to make an armature in the alternating current shunt release work and realize opening operation.

The invention relates to a photovoltaic module quick turn-off protection device with low cost and high reliability. The photovoltaic module quick turn-off protection device is powered up by a power grid, is arranged between a photovoltaic module and an inverter and is connected between the photovoltaic module and the inverter by virtue of an IGBT and a normally closed alternating current relay, wherein IO is a normally closed alternating current relay driving signal, G1 is an IGBT driving signal, a time sequence control circuit respectively gives the IGBT driving signal G1 or the normally closed alternating current relay driving signal IO; when input of the power grid is present, the time sequence control circuit guarantees that a normally closed alternating current relay is turned on before an IGBT; and when the power grid is turned off, the normally closed alternating current relay is turned off after the IGBT, so as to guarantee that the normally closed alternating current relay isturned on and off under the condition that no direct current exists. The photovoltaic module quick turn-off protection device provided by the invention solves the arc discharge problem of the alternating current relay, and cost is greatly reduced; the device is small in volume and can be conveniently mounted below the module, and the requirement of being 3m away from the module is met; and turn-off protection is fast, safe and reliable, and personnel do not need to go to a roof.

The invention relates to a novel dual-power-driven type electric hoist of a crane, which is characterized in that a set of motors with same parameters, a speed reducer and a brake are respectively arranged at two ends of a reel; on a control circuit, two motors are connected in parallel together in the circuit and controlled by the same control electromagnet; same overcurrent relays and same ampere meters are connected into a branch of each motor, and control contacts of each overcurrent relay in the branch of each motor are serially connected in the control circuit.

The invention relates to a self-powered digital over-current relay, which integrates electric quantity monitoring, relay protection, microcomputer control and communication into a whole, really solves the problems that 5kv/10kv switching stations, power distribution stations, ring main units and the like have no power supply and need protection function, and greatly improves the safety of power distribution networks. The relay comprises a single chip microcomputer, wherein the input end of the single chip microcomputer is connected with a multichannel current analog signal, an AC sampling circuit, an automatic gain amplification circuit and a DIP dial switch respectively; the output end of the single chip microcomputer is connected with an output circuit; a serial port of the single chip microcomputer is connected with a communication interface; all hardware circuits of the single chip microcomputer are provided with a watchdog resetting and low-voltage monitoring circuit and a FALSH memory; the single chip microcomputer is PIC24FJ128GA006; the multichannel current analog signal is connected with the input end of the AC sampling circuit through the output end of a current transformer; and the output end of the AC sampling circuit is converted by the automatic gain amplification circuit and then is connected with an A/D acquisition interface inside the single chip microcomputer.