1198 results about "Grounding Malfunction" patented technology

The invention relates to a device and a method for detecting and positioning small current earthing fault. The device comprises a slave computer and a host computer composed of a CPU module, a DSP, a pre-loop unit module, a A/D conversion module, a memory module, a display and keyboard operation module as well as a communication module; wherein, the pre-loop unit module, the A/D conversion module, the CPU module and the DSP are connected in sequence; the memory module, the display and keyboard operation unit module and the communication module are respectively connected with the CPU; the host computer is connected with the communication module. The CPU module collects the analog signal of the zero-sequence voltage of the bus and the zero-sequence current of each line, and adjusts the value in proportion to the amplitude range so that the device can deal with. The analog signal is turned into digital signal recognized by the computer module, and analyzed by the DSP to judge whether the fault occurs or not. If the fault occurs, then the DSP gives the line selection result, saves the fault information and transfers the line selection result to the host computer for fault alarm.

A new type of switching mechanism for a ground fault circuit interrupter (GFCI) with reverse wiring protection preferably includes two pairs of fixed contact holders, each member of each pair having at least one fixed contact at one end; a pair of movable contact holders, each having an end having one or more of movable contacts, each movable contact being arranged for contacting one of the fixed contacts; and a movable assembly that moves between first and second positions, wherein the first position is a position in which each of the contacts of the fixed contact holders makes contact with one of the contacts of the movable end of one of the movable contact holders, and wherein the second position is a position in which the contacts of the fixed contact holders are separated from the contacts of the movable contact holders.

The invention discloses a distributing net single phase earth fault type and a distinguishing method of phase identification, relating to a distributing net single phase earth fault distinguishing method in the field of AC distributing net testing and relaying protection technology. According to the invention, through collecting three-phase voltage of the distributing net system and neutral point voltage of the distributing net system, phase angle of each eigenvector is computed through a special relation, the type of the fault and the phase identification can be fast distinguished through the phase angle distinguishing logic. The inventive working system is that a three-phase bus (000), a grounding transformer (100), a linear side of an arc suppression coil (200) are connected in turn with the earth; a controller (400), a thyristor (300) and a secondary side of an arc suppression coil (200) are connected in turn. The invention is simple in criterion, small in collection quantity, fast in distinguishing speed, high in accuracy, reliable in security, which is suitable for 3-66 KV distributing net based on an aerial line or a power cable.

The present invention relates to a reverse wiring protection device for ground fault circuit interrupter that includes a tripper and control circuit. The tripper comprises: a pull rod with flat, a L-shaped latch, a balance frame coupled with the latch moving up and down with the pull rod, a trip coil, a plunger and a contact switch (K) which is capable of energizing and de-energizing the trip coil. The reset can't be depressed when an installer or user miswires the line and the load. GFCI can only be operating normally when it is installed properly

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 present invention is implemented by deploying an enhanced ground fault detection and location apparatus and by using the apparatus in conjunction with specific circuit analysis methods, using the information generated by the ground fault detection and location apparatus. The ground fault detection and location apparatus comprises the functionality of a voltmeter, an ammeter, a frequency generator, and a variable power supply, thereby providing for a variety of signals and analyses to be performed on a unintentionally grounded circuit in an ungrounded AC or DC power distribution system. The apparatus includes a main unit and a remote unit, which may be a portable hand-held unit. In a first mode, the apparatus of the present invention can be used to detect ground faults. By switching to a second mode, the apparatus of the present invention can be used to locate ground faults. The methods of the present invention involve the generation of various signals by the main ground fault detection and location unit. The generated signals are introduced into the electrical distribution system and monitored by various means, including one or more remote units. By analyzing the system-level response to the generated signals, the specific location of the ground fault or faults can be more readily ascertained, thereby promoting rapid and efficient repair and recovery practices. The apparatus of the present invention may be implemented as a dedicated, permanent installation or as a temporary portable system. Additionally, the system may be implemented as an automatic computer-controlled ground fault location and detection system.

The present invention is directed to an inductively driven electromagnetic linear actuator arrangement employing eddy currents induced by a fixed drive coil to drive its armature. Eddy current focusing fields are employed to direct the eddy currents using Lorentz forces to maximize armature speed. The armature includes a shorted driven coil in a DC magnetic field. This can be supplied by a permanent magnet. When current is applied, a force is felt by the coil in a direction perpendicular to the magnetic field. Such an actuator is well suited for electrical switching applications including transfer switching applications, circuit breaker applications, and ground fault interrupter applications.

The invention relates to a method for detecting and positioning section faults of a power distribution network containing distributed generators, which comprises a fault judging and positioning part and a fault type recognition part. A fault judging and positioning method comprises the steps of detecting a fault and recognizing a fault phase through comparing the relation between an absolute value of the phase angle difference of each phase current of each power system section and a threshold value, finding out a section where a fault point is located, and timely removing the fault section so as to complete a protection action. A fault type recognizing method comprises the steps of comparing zero-sequence current amplitude values at two end nodes of the fault section at the fault determination moment with a set threshold value on the basis of recognizing the fault phase, and judging whether the zero-sequence current amplitudes at the two end nodes of the fault section at the fault determination moment are less than or equal to the threshold value or not, thereby determining whether the fault is a phase-to-phase fault or a grounding fault. The method provided by the invention can be applied to detecting and positioning the section faults of the power distribution network containing the distributed generators under high permeability.

The present invention provides a circuit interrupting device, preferably a ground fault circuit interrupter (GFCI), which contains a dual-function test button having a short pole and a long pole positioned underneath the dual-function test button. When the GFCI is properly wired and powered, a depression of the dual-function test button allows the short pole to operatively connect to a conductive pin and generate a leakage current to test the components of the GFCI. If all of the components are functioned properly, the GFCI can be reset. If not, the GFCI cannot be reset. When the GFCI is miswired or reverse wired and not powered, a depression of the dual-function test button does not test the components of the GFCI. However, a further depression of the dual-function test button allows the long pole presses against a tripping lever on a locking member in a tripping device which mechanically trip the GFCI. The present invention further provides an end-of-life detection circuit which can automatically generates a simulated leakage current to test the components in the GFCI. If one or more components are not functioned properly, the end-of-life circuit prevents the GFCI from resetting.

The invention provides a symmetrical bipolar MMC DC-side single-pole ground fault ride-through and recovery method. Through cooperation of a DC circuit breaker and a converter, DC fault current cut-off and power recovery are realized, and safe operation of the converter is protected. Through cooperation of active power and reactive power of the sound pole and the faulty pole, the active power deficiency of a converter station in the failure period is reduced. Rated reactive power is supplied to the grid, and therefore, the impact of a fault to an AC system is reduced. By actively controlling the common-mode components of the reference voltages of the upper and lower bridge arms of the converter, the risk brought to the safe operation of the system by excessive current surge stress of the converter due to reclosing failure is avoided. Based on the fact that a dual-pole short-circuit fault at the DC side of a symmetrical bipolar MMC can be regarded as a special case of single-pole ground faults of both positive and negative DC buses, the method of the invention can be used to handle a dual-pole short-circuit fault at the DC side of a symmetrical bipolar MMC.

A non-isolated power supply is configured to receive an input voltage and supply an output voltage, and includes a supply line, a return line, a first semiconductor switch coupled in series in the supply line, and a second semiconductor switch coupled in series in the return line. The first and second semiconductor switches are each configured to operate in an ON state and an OFF state. The differential current sensor is configured to sense differential current between the supply line and the return line. The fault detection logic is coupled to the differential current sensor, the first semiconductor switch, and the second semiconductor switch, and is configured to detect when the differential current exceeds a predetermined current magnitude, and command the first and second semiconductor switches to operate in the OFF state upon detecting that the differential current exceeds the predetermined current magnitude.

The invention relates to a single-phase earth fault location system for a distribution network of a power system and a method thereof. The single-phase earth fault location system comprises a pulse signal generator, which is arranged between the neutral point of a main substation transformer and the ground, and the initial end of each outlet branch is provided with a current sensor; and a main station is also mounted in a substation, and is communicated with the current sensors. The method installs the thyristor-based short-circuit current generator at a corresponding position in the substation, thyristors are controlled to instantaneously conduct in order to generate and inject short-circuit current into a faulty line, the sensors mounted on the initial ends of the outlet branches detectthe short-circuit current, each sensor detecting the short-circuit current informs a host positioned in the substation of own state information via communication, and according to calculated fault impedance coupled with the locations of the sensors detecting the short-circuit current, the host determines the location where a single-phase earth fault occurs.

The invention discloses a fault diagnosis comprehensive positioning method for an intelligent distribution network, and belongs to the field of fault monitoring. Based on a fault indicator, a wirelesscommunication technology and a ground fault line selection technology, the method comprises the following steps: monitoring zero-sequence voltage of a transformer neutral point in real time, startingzero-sequence fault diagnosis when detecting that a zero-sequence voltage change value exceeds a preset value, and identifying whether the zero-sequence voltage change value is a single-phase grounding fault; if the zero-sequence voltage change value is single-phase grounding fault, performing grounding line selection through a fault diagnosis device in a station, and positioning the grounding fault on a certain phase of a certain line; when the single-phase earth fault is judged to be a stable fault, recalling the real-time current data of the fault indicators on the fault phase line, comparing the signals collected by the fault indicators, comparing the difference of the real-time current data before and after a fault point, judging the two fault indicators with abrupt changes, and thendetermining the specific section of the fault. The method can be widely applied to the field of power distribution network operation fault monitoring and positioning.

The invention provides a coal mine grid system insulation state monitoring method and belongs to an electrical power system feed line insulation state monitoring method. A feed line branch circuit is selected for doing single-phase longitude metal grounding experiment, zero sequence voltage of a bus and zero sequence current of a non-malfunction branch circuit are tested, zero sequence impedance of the non-malfunction branch circuit is obtained, namely, insulation resistance and ground capacitance, for obtaining insulation parameters of all circuits, another branch circuit is reselected to do a single-phase connection low resistance ground experiment or the next circuit with the non-branch-circuit number 1 is waited for generating single-phase ground malfunction, the experiment is repeated, insulation parameters of a first experiment malfunction circuit are obtained, and the insulation parameters of all feed line branch circuits are obtained by synthesizing results of the two experiments. The coal mine grid system insulation state monitoring method has the advantages that insulation degradation degree of the circuits is analyzed from state change of the bus zero sequence voltage and an arc suppression coil, the zero sequence voltage changes to a certain extent, switching-in situations of damping resistance change, and the degradation degree of circuit insulation is forecasted by monitoring change of transient states of a plurality of feature quantities.

The invention relates to a small earth current grid single-phase grounding fault wire-choosing method, which comprises: 1) Collecting the zero order voltage and the zero order current signal on the voltage sensor and the current sensor of each wire and computing the zero order voltage amplitude, if the amplitude is over the limit, it quotes that it occurs the fault and collects the zero order current after four period of the fault; 2) computing the second, third and forth period effect value I1, I2 and I3 when each line zero order current fault starts and computing the gradient factor K1, K2 of each line zero order current; 3) quoting weather it satisfies K1ú¥KSET and K2ú¥KSET, wherein KSET is the gradient factor setting value with the range 1.2-2.0; 4) if it satisfies K1ú¥KSET and K2ú¥KSET, the wire is earth fault wire. The wire-choosing system comprises a microcomputer including a fault detecting open unit, a zero order current gradient computing unit and a transient gradient wire-choosing unit.

The invention elates to a ground fault protecting circuit and a ground fault breaker. The circuit comprises a power circuit, a leakage ground detecting circuit, a signal amplifying shaping circuit, a single-chip control circuit, a power detecting and working indicating circuit, a releasing mechanism control circuit and a reversed wiring detecting and performing circuit; a first filter voltage stabilizing circuit of the power circuit is connected with the leakage ground detecting circuit; a second filter voltage stabilizing circuit is connected with the signal amplifying and shaping circuit and the single-chip control circuit; the leakage ground detecting circuit, the signal amplifying and shaping circuit and the single-chip control circuit are connected in sequence; the single-chip control circuit is respectively connected with the power detecting and working indicating circuit and the releasing mechanism control circuit; the breaker comprises a breaker body and a ground fault protecting circuit which is arranged in the breaker body. According to the ground fault protecting circuit and the ground fault breaker, the reversed wiring detecting and performing circuit and a simulating leakage circuit are added to avoid the potential risk caused by inaccurate wiring and leakage fault, and therefore, the protection safety of the circuit can be improved.

The invention provides a distance measuring method for a double return line single phase grounding fault of a small grounding current system. The method comprises the following steps: 1, double return lines in different positions are coded, and arranged in a microcomputer of a grounding transfer device in advance; and 2, a microcomputer carries out real time acquisition and calculation of phase voltage, line voltage and zero sequence voltage of a bus and zero sequence current of other circuits of a transformer substation, judges the grounding and grounding phase of the system, and gives a switch-on command to a split phase switch of the grounding phase, and a wave recording command at the same time when the single phase grounding fault occurs in the system; after wave recording; by the combination of the codes of the double return lines, the microcomputer carries out the line selecting operation through the measured zero sequence voltage and zero sequence current; and then by the measured double return line first line grounding current split current value equation, the measured double return line second line grounding current split current value equation, the measured flow-in fault point current value equation and the measured distance equation between the tail end and the fault point of the circuit, the microcomputer can work out the position of a grounding point when the grounding point of the double return lines is grounded, namely the distance between the tail end and the fault point of the circuit.

The invention provides a direct grounding insulation fault detection device and method with simple hardware circuit, high detection precision and no adverse effect on the DC system itself. The detection device includes a first voltage dividing circuit (110), a second voltage dividing circuit (120), a voltage equalizing circuit (130), a measured insulation resistance RX1 and a measured insulation resistance RX2, and the method is to pass the voltage equalizing circuit (130 The control of the on and off of the switch tube in ) produces two effective circuit states, and the relationship between the midpoint voltage and the bus voltage in the two states is used to realize the low-cost and high-precision detection of the direct grounding resistance. This method uses the unbalanced bridge method to give a more accurate formula for the positive and negative insulation resistance of the DC system when the insulation values ​​of the positive and negative busbars are reduced, in order to prevent the power system from being caused by DC grounding. Misoperation provides a scientific and effective detection method.

A selective protection method for single-phase earthing of generator stator uses three times of B-spline wavelet as an analysing tool to directly analyse the measured voltage at two sides of generator end and neutral point as well as zero sequence current, and it can be sure that 100% of earthing fault of generator stator can be identified reliably by this method which works as using standard connection form for voltage and current mutual-inductor, calibrating the phase of zero sequence current at generator end, using mode maximum value as a start element after zero sequence voltage being analysed by B-spline wavelet, to judge whether the earthing fault of internal single plase of generator stator is produced or not by checking that the mode maximum value of zero sequence current at generator end and zero sequence voltage of generator end and neutral point side is in an uniformity or not through the analysis by B-spline wavelet.

The invention relates to a small current grounding system fault line selection method using power frequency component wavelet coefficients to carry out linear fitting detection, and belongs to the field of a power system relay protection technology. The small current grounding system fault line selection method includes the steps of being capable of obtaining fault zero sequence current according to measured three-phase current at a protection installing position after a single-phase earth fault of a small current grounding system occurs, carrying out wavelet decomposition on the zero sequence current of each feeder line of a 5-millisecond short time window after the fault occurs, extracting the wavelet coefficients containing power frequency bands, carrying out linear fitting on the wavelet coefficients, representing variation trend of the power frequency bands of the zero sequence current of the feeder lines by using polarity of obtained fitting straight slope, and constructing feeder line selection sign functions according to the rule that the variation trend polarity of the power frequency bands of the fault feeder lines is opposite to the variation trend polarity of the power frequency bands of the faultless feeder lines, and variation trends of the power frequency bands of the faultless feeder lines are same. If a sign function value of one of the feeder lines is minus one, then the feeder line is the fault feeder line, on the contrary, if the sign function value of one of the feeder lines is one, then the feeder line is the faultless feeder line, and if the sign function values of all the feeder lines are one, then faults happen to buses. The small current grounding system fault line selection method is simple in principle, low in sampling frequency, and capable of achieving correct line selection when the faults happen on the conditions of initial fault current angles of the small faults.