342 results about "Ground failure" patented technology

The invention discloses a distribution network ground fault arc extinction and protection method, which comprises the following steps of: measuring a three-phase voltage and a zero sequence voltage of a distribution network, and detecting a ground fault and a fault phase; when the ground fault happens, injecting a current into the distribution network and forcibly zeroing the voltage of the faultphase and the current of the ground fault; delaying a period of time and reducing the injected current; if the zero sequence voltage is reduced proportionally, indicating that the fault point is subjected to arc extinction, determining that the fault is an instant fault, reducing the injected current to zero and recovering the normal running of the distribution network; otherwise, determining that the fault is a permanent fault, changing the injected current, detecting and isolating a fault feed line according to the variation of a zero sequence current, and recovering the normal running of the distribution network. By the method, the voltage of the fault phase is used as a control target, so total arc extinction of the instant fault and quick isolation of the permanent fault can be realized by injecting the current and forcibly zeroing the voltage of the fault phase; and the technical difficulties in poor arc extinction effect of the current arc extinction method and low reliability of the conventional protection method are overcome.

A ground fault detector and detection method for a vehicle that can determine the cause of the occurrence of a ground fault after detecting the presence of the ground fault. The output terminal of a high-voltage battery is connected to one side of a coupling capacitor. In operation, a pulse signal is applied to a measurement point on the other side of the coupling capacitor, and the voltage generated at that point is detected. Whether the high-voltage battery or the electrical equipment units are grounded is determined. To determine the cause of the ground fault, the oscillation frequency of the square-wave pulse signal is changed and applied to the measurement point. From the change in voltage amplitude detected, it is determined whether the cause of the ground fault is a resistive or a capacitive ground fault, according to the change in the impedance of the battery or the units.

During charging operations of a power storage unit, a voltage converting unit converts a voltage received from direct-current buses and supplies it to power storage unit, whereas during discharging operations of power storage unit, voltage converting unit converts a voltage received from power storage unit and outputs it to direct-current buses. In voltage converting unit, a side connected to power storage unit and a side connected to direct-current buses are insulated from each other. As a result of this, if a ground failure occurs in power storage unit, its effects on an inverter circuit, a commercial power system and the like are prevented. A grid-connected power conditioner with high safety can thus be obtained.

A motor drive system provides for analysis of current flow in the DC bus to identify ground faults and their locations. Low-frequency positive polarity and negative polarity current differences indicate ground faults from the positive DC bus and negative DC bus respectively. High-frequency signals indicate ground faults in the motor windings and connecting leads.

A self testing fault detector having a line side and a load side and a conductive path there between, said apparatus is provided. The self testing fault detector includes a controller, adapted to perform periodic status tests on a protection circuit of the self testing fault detector without interrupting power to the load.

A method for determining the grounding failure segment of feed line in low-current grounding system includes monitoring the zero sequence voltage and current of each distribution switch on a feed line, judging system failure if the zero sequence voltage is greater than a setting value, calculating the variation of zero sequence current of each switch to find out the zero sequence current flowing from all the switch into the segment, and judging the failure state and position according to the ampletude and phase characteristics of the zero sequence current flowing into different segments.

A ground fault circuit interrupting device detects an end-of-life condition. A ground fault detecting circuit detects a fault condition and controllably operates a switching device to energize a circuit interrupting device. An end-of-life detecting circuit detects a failure of the circuit interrupting device to open after detection of the fault condition, and activates a secondary circuit to energize the circuit interrupting device.

A method and system is provided for detecting and performing diagnostics regarding an incipient ground fault that may occur in an electrical propulsion system of a traction vehicle, such as a locomotive, transit vehicle, or off-highway vehicle. The method allows providing a first ground connection for the electrical propulsion system. This first ground connection forms a grounding path generally used by the electrical propulsion system during normal operation. The method further allows providing a second ground connection for the electrical propulsion system. This second ground connection forms a grounding path selectively usable in lieu of the first ground connection. A control strategy is defined for switching between the first ground connection and the second ground connection. A respective leakage current associated with at least one of the first and second ground connections may be monitored. Switching between the first and second ground connections may be controlled based on the monitored leakage current associated with at least one of the first and second ground connections.

The invention relates to a measuring post simulation method of the fault wire selection for a low current grounding system. The invention belongs to the technical field of the power system relay protection. The method is realized by that when the instantaneous value of the voltage of a bus zero exceeds the limit, a fault wire selection device is started immediately and used for recording the wave. The invention adopts a digital filter algorithm to obtain the bus zero voltage and the transient pure fault components of zero current on each feedback line. When a low current grounding system takes place a single-phase earth fault, the waveform of the zero current is quantitatively solved by using measuring post simulation according to the transient pure fault component of the measured value of the bus zero voltage and the feeder zero distribution capacitor parameter under the assumption premise of the perfect feeder of every feeder. The invention carries out correlativity analysis to compare the measured waveform of the current of every zero current with the transient pure fault component solved by the measuring simulation method under a definite data window and calculate both correlative coefficients, thereby the invention forms a line selecting criterion 1 and 2 and can carry out line selection to the system according to the line selecting criterion. The principle analysis and the simulation show that the line selection method has the advantages of accuracy and reliability.

The invention relates to a method for locating a single-phase disconnection non-ground fault of a power distribution network. After the single-phase disconnection non-ground fault occurs, the positive sequence voltage of the high-voltage side of each distribution transformer after a fault point is far lower than the positive sequence voltage of the high-voltage side of each distribution transformer before the fault point and the positive sequence voltage of the high-voltage side of each distribution transformer of a non-faulty line, and the positive sequence voltage of the low-voltage side of each distribution transformer after the fault point also correspondingly becomes about 50 percent of the positive sequence voltage before the fault point. For three-phase voltage information acquired by different types of measuring devices installed at load points, the positive-sequence component of the voltage of each load point is calculated in real time; and if the positive sequence voltage of a certain load point and the positive sequence voltages of all downstream load points of the load point are obviously reduced at one point, and the positive sequence voltages of upstream load points of the load point are constant, the single-phase disconnection non-ground fault can be determined in an upstream adjacent line connected with the load point. According to the method for locating the single-phase disconnection non-ground fault of the power distribution network disclosed by the invention, new equipment does not need to be equipped; the calculation is simple; and the fault can be located between two load points to realize the diagnosis and the location of the single-phase disconnection non-ground fault.

The invention discloses a grounding line selection method, a grounding line selection device and an application system based on an active component of a zero sequence current. The grounding line selection method and the grounding line selection device based on the active component of the zero sequence current are used for a distribution network system comprising a plurality of outgoing lines and a bus for grounding line selection protection when single-phase grounding failure occurs. The grounding line selection method comprises the steps of: zero sequence current compensation for compensating measured value of the active component of the aero sequence current of each outgoing line according to the distribution situation of the active component of the aero sequence current of the plurality of outgoing lines; line selection after the compensation, which is used for sequencing the active components of the compensated zero sequence currents of the plurality of outgoing lines according to the amplitude size and selecting the outgoing line the zero sequence current of which has maximum active component amplitude; and line selection protection which is used for comparing the maximum active component amplitude of the outgoing line of the zero sequence current with the threshold value, judging that the branch of the outgoing line is the grounding failure line if the maximum active component amplitude is more than the threshold value, otherwise, judging that the branch of the outgoing line is the bus grounding line if the maximum active component amplitude is less than the threshold value.

A safety outlet that prevents hazardous conditions is described. Embodiments of the outlet use safe low-voltage DC power to check and ensure that an appliance is plugged into the outlet, that the appliance does not have short circuits or ground faults, and that the appliance is switched on. Some embodiments warn of unsafe conditions. Until the safety checks are performed and satisfactorily passed, embodiments of the outlet keep the AC power turned off and isolated from the outlet. Only then is the receptacle powered, after which the appliance can be used normally. Once the appliance is switched off, the power at the outlet is also turned off automatically. When an appliance is in use, some embodiments of the invention continue providing ground fault protection using GFCI technology. All this is performed automatically and quickly, nearly imperceptibly in normal use. Some embodiments may be integrated with external control systems.

The invention is a kind of one-way grounded failure selecting method and the device for a kind of small-current grounding electric network: at first, a 10kV physical simulating lab for the small-current grounding select is crated. The lab system discloses the essence of the running principle and the grounding failure of the small-current grounding electric network, it reappears some failures such as arc light grounding, intermittent arc light grounding, large-resistance grounding, and instable large-resistance grounding. And it researches the intelligent colony amplitude and phase comparing method, wavelet method, sample constructing method, current mutating method, network method which is suitable for each kind of grounding modes such as non-slip point grounding and non-slip point grounding through the arc eliminating coil; it provides the effective region analysis and the continuous judgment technology in the first; and it provides and uses the evidence theory, failure measuring theory, coarse group theory and several criteria intelligent fusion idea.

The invention provides a method for positioning a single-phase grounding failure of a distribution network containing a distributed power supply, and the method can be used for dividing the distribution network into sections and constructing a distribution network failure positioning software and hardware system. When the distribution network is determined to have a permanent grounding failure, a failure positioning program is executed, and data is collected step by step to realize failure phase section, failure wire selection and failure section selection. Failures can be positioned accurately step by step, so that the method is higher in reliability and accuracy, is in accordance with automatic construction of the distribution network, can be used for saving the equipment cost and the data storage space of a master station, is high in positioning speed, and is suitable for the traditional distribution network and the distribution network containing the distributed power supply.

A data communication system for use in downhole applications wherein electrical energy is supplied over a multiple-conductor power cable to an ESP motor assembly. A downhole unit is AC-coupled to the conductors of the power cable through the wye point of the ESP motor assembly. A surface unit is AC-coupled to the conductors of the power cable. Uplink communication of telemetry data occurs over an AC communication scheme supported by the downhole unit and the surface unit. Downlink communication of remote control command data occurs over a different AC communication scheme supported by the surface unit and the downhole unit. These AC communication schemes provide an independent supply of power to the downhole environment. All communication between the surface and downhole environment is accomplished through the power cable without the use of additional communication lines. Data communication is maintained in the event of a ground fault on the power cable.

An apparatus and method for a supervisory circuit for a ground fault detection device or ground fault circuit interrupt (GFCI) device is disclosed in which is a test stimulus signal for a self test of the GFCI device is generated on a second secondary winding on a toroid of a differential current transformer. The GFCI device includes line and neutral conductors configured to connect an AC power source and a load. A differential current transformer includes a toroid, through which the line and neutral conductors pass, a first secondary winding wound on the toroid to generate a current in response to an imbalance of magnetic flux in the toroid, and a second secondary winding wound on the toroid. A differential ground fault detector is electrically connected to the first secondary winding of the differential current transformer to compare current generated in the secondary winding to a trip threshold. A controller is configured to control a test stimulus signal to be generated in the second secondary winding wound on the toroid of the differential current transformer.

A monitoring system for detecting earth faults in an electrical power supply grid providing a power signal includes a plurality of monitoring devices, each of the monitoring devices including a detector for detecting the level of harmonics in the power signal, wherein the level of harmonics is detected in a specific frequency range. Each of the monitoring devices further includes a memory for storing a harmonics reference value, a processor for comparing the detected level of harmonics with the reference level, and a communication device for transmitting an alarm if the detected level of harmonics is above the reference level for a specific period of time. Each of the detectors includes an optical sensor for detecting the harmonics by use of the Faraday effect.

The invention discloses a fault diagnosis method which is used for determining whether a single-phase earth fault occurs in a low current earth system and determining the position of a fault point. The method comprises the following steps of: (102) synchronously acquiring the power frequency voltage of a busbar of the low current earth system and the current traveling wave of all outgoing lines in real time; (104) determining an outgoing line with turbulence in all the outgoing lines when the turbulence occurs in the low current earth system; (106) determining whether the single-phase earth fault occurred in the low current earth system according to the power frequency voltage; and (108) determining the outgoing line with the turbulence as a faulty outgoing line to obtain the distance between the acquisition point and the fault point on the current traveling wave of the faulty outgoing line when the single-phase earth fault occurred in the low current earth system. The invention discloses a fault diagnosis device. The single-phase earth fault of the low current earth system can be detected according to the fault diagnosis method and device.

A circuit breaker includes a test circuit having one or two indicators, an arc fault signal generator, and first and second test switches. A first indicator is electrically connected in series with the first test switch. This series combination provides a first alternating current signal to the arc fault signal generator, which provides an arc fault signal to an arc fault trip circuit, in order to trip open separable contacts in response to closure of the first test switch. The series combination of the second test switch and the second indicator provides a second alternating current signal to a ground fault trip circuit, in order to trip in response to closure of the second test switch. The indicators provide a visual indication of failure of the arc fault or ground fault trip circuits to trip in response to closure of the first or second test switches, respectively.

A ground fault sensing device for a drive system that converts direct current electrical power from a direct current power supply into alternating current electrical power and drives an electric motor with that alternating current electrical power, comprises: an extraction circuit that is connected to a power supply line of the direct current power supply via a coupling capacitor, that detects an amplitude wave that is generated when an alternating current side including the electric motor is suffering a ground fault, and that extracts the envelope of the amplitude wave; a measurement circuit that measures the voltage level of the envelope; and a determination circuit that makes a decision as to whether or not a ground fault has occurred on the alternating current side by comparing together the voltage level measured by the measurement circuit and a ground fault decision value.

In an off-road vehicle having a resistor grid network and a blower system as part of a braking system operable to determine at least one of a resistor failure and a blower failure, the system including a first series of resistors connected in series, a second series of resistors connected in series, a blower cross to at least one of the first series of resistors and the second series of resistors, a sensor proximate at least one of the first series of resistors, the second series of resistors, and the blower, wherein each individual resistor in the first series connected in parallel to an individual resistor in the second series, and wherein when at least one of a current value, blower speed, and voltage value changes, the grid network is disconnected.

The invention discloses a method for staring longitudinal differential protection by using a fault component. The method mainly comprises the following steps of: after power side longitudinal differential protection meets three conditions, including a protection starting action criterion, a zero sequence or negative sequence positive direction action criterion and a zero sequence differential protection action criterion, starting a fault component; transmitting a fault component starting signal to weak feedback side longitudinal differential protection through an optical fiber channel; and if protection is not started after the weak feedback side longitudinal differential protection receives a power side fault component starting signal, and meets the zero sequence differential protection action criterion, starting driving protection, so that differential protection on both sides can act. Due to the adoption of the method, the problem of insufficient staring sensitivity of weak feedback side longitudinal differential protection during a high-resistance ground fault is solved.

A low resistance grounding system single phase grounding fault protection method belongs to the power distribution network relay protection field. A generation probability of a low resistance grounding system high resistance grounding fault is large. A zero sequence overcurrent protection method of a traditional fixed setting value is easy to generate unwanted operation. In the method, according to a relation among a fault point transition resistor, a zero sequence voltage and each outgoing line zero sequence current when a grounding fault is generated, the zero sequence voltage is taken as a brake amount so as to determine a zero sequence overcurrent protection setting value. If a zero sequence voltage amplitude is greater than a knee point voltage, the zero sequence overcurrent protection setting value is increased according to a certain proportion; otherwise, the zero sequence overcurrent protection setting value keeps the same and is a set value during normal operation. By using the method, adaptive adjustment of the zero sequence overcurrent protection setting value under the condition of the different transition resistors can be realized; and protection sensitivity to a small resistance grounding fault and a metallicity grounding fault and protection reliability to a high resistance grounding fault are considered.

The invention discloses a high-voltage direct-current transmission line high-resistance grounding fault identification method based on distributed parameters. The method comprises the following steps that step 1, direct-current line current at a rectification station side and direct-current line current at an inversion station side are monitored in real time, if the condition (||IR|-|II||) I set is satisfied in continuous 3ms, the existence of a fault point in a high-voltage direct-current transmission line is judged, and then a step 2 is conducted; step 2, fault point residual voltage URFm is calculated at the rectification station side and fault point residual voltage UIFm at the inversion station side is calculated respectively, and if URFM>=0.1IdR, an in-zone high-resistance grounding fault is judged, and a protecting outlet t1 is delayed; if URFm< 0.1IdR, an in-zone metal fault is judged, and a protecting outlet t2 is delayed. According to the high-voltage direct-current transmission line high-resistance grounding fault identification method based on the distributed parameters, the fault point residual voltage when the high-voltage direct-current transmission line grounding fault occurs is compared with initial stable voltage when high-resistance grounding fault occurs, whether the high-resistance grounding fault occurs or not is judged, so that the protecting outlet is started, the protecting outlet is not influenced by transition resistance, the shortage of protection of motion rejection when the high-resistance grounding fault occurs in a current direct-current line is compensated, and the flexibility of protection motion is improved.

A circuit breaker includes a test circuit having one or two indicators, an arc fault signal generator, and first and second test switches. A first indicator is electrically connected in series with the first test switch. This series combination provides a first alternating current signal to the arc fault signal generator, which provides an arc fault signal to an arc fault trip circuit, in order to trip open separable contacts in response to closure of the first test switch. The series combination of the second test switch and the second indicator provides a second alternating current signal to a ground fault trip circuit, in order to trip in response to closure of the second test switch. The indicators provide a visual indication of failure of the arc fault or ground fault trip circuits to trip in response to closure of the first or second test switches, respectively.

A ground fault detector and interrupter for a photovoltaic (PV) energy conversion system, method and apparatus are disclosed. In an exemplary embodiment, the system includes first and second inputs adapted to couple to a first and second rails of a PV array. An inverter is configured to convert DC power generated from the PV array to AC power. A ground fault detector and interrupter, which is coupled to the first and second rails and to the inverter, is configured to detect ground fault conditions in the PV array and to decouple the PV array from the remaining portion of the PV energy conversion system upon such detection. A known signal is coupled to the input of the ground fault detector and interrupter, and then sensed at the output of the ground fault detector and interrupter to determine whether components of the ground fault detector and interrupter are operating properly.

The invention relates to a method and device for flexibly identifying residual current-type electrical fire on line. The method comprises the following steps: arranging a residual current mutual inductor in a power transmission and supply circuit of a low-voltage power distribution system; obtaining an instantaneous value irz of lumped residual current in the circuit as well as waveform which areacquired by the mutual inductor through a power supply branch residual current and other signal detection unit; and according to the characteristics such as abrupt change, discontinuity and nonlinearity of a spot-heat agglomeration residual current instantaneous value ird, separating and extracting ird from irz by adopting a modern information processing technology, and calculating an effective value Ird of ird so as to identify whether potential electrical fire danger exists according to the size of Ird. The on-line identification device consists of three parts such as a residual current signal processing unit, the power supply branch residual current and other signal detection unit and an output execution unit. By adopting the residual current-type flexible on-line electrical fire identification method and device, the features of the potential electrical fire danger caused by electric arc grounding faults can be accurately extracted, normal residual current and abnormal residual current can be correctly identified, and alarm failure and false alarm can be avoided.

A device and method to determine the presence of a ground fault that distinguishes between the capacitive portion of the currents to ground, and the resistive portion of the currents to ground by ascertaining aspects of the voltage and residual current waveforms.

The invention discloses a fast judgment method and a system for a power supply system distribution network single phase grounding fault line. The method comprises steps: open delta voltage of a secondary side of a PT or first end zero sequence current of each feeder line or a branch line is monitored in real time, monitoring information is generated, and whether single phase grounding fault happens to the system is judged according to the monitoring information; when the single phase grounding fault is judged, a neutral point displacement voltage state and a three-phase voltage state are monitored, and according to the neutral point displacement voltage state and the three-phase voltage state, a fault phase is determined; and fast switching closing is carried out on a bus fault phase, first end zero sequence current change features of each feeder line and each branch line are monitored and analyzed at the same time, and according to the zero sequence current change features of each feeder line and each branch line, a fault line is selected. The method and the system disclosed in the invention have the advantages of accurate and high-efficiency fault line judgment.