141 results about "Multipoint ground" patented technology

The invention discloses a single pole grounding system and a fault detection device and method. According to the single pole grounding system and the fault detection device and method, before the grounding of a normal grounding point, the direct current bus voltages of a system and impedance sampling signals are obtained to calculate the earth impedance of the positive / negative pole of the single pole grounding system, then whether fault grounding points exist is judged, pre-detection before system operation is achieved, and no faults exist before the operation of the system; after the normal grounding points are grounded, whether a grounding fault exists is judged by detecting leaked currents; the grounding pole multipoint grounding fault and non-grounding pole grounding fault which occur during the operation process can be detected when the system is down or the normal grounding points are not grounded through calculating the earth impedance of the positive / negative pole of the single pole grounding system again. Thus, the single pole grounding system and the fault detection device and method achieve the detection on the multipoint grounding fault of the single pole grounding system and the non-grounding pole grounding fault which may occur at the same time.

A fuel pump module has a flange located proximate to the top of the fuel tank, a first strut rod, a second strut rod, a fuel inlet tube and a fuel outlet tube, each extending through the flange from a first side of the flange to a second side of the flange. A multi-point grounding plate is located on a side of the flange to contact and ground the strut rods, fuel tubes and adjacent parts. The grounding plate is generally disposed about a periphery of the flange, and a grounding wire, a first end of which is disposed on the grounding plate and a second end of which is disposed on a vehicle ground location, provides the necessary grounding path for the grounding plate.

The present invention discloses an antenna device for a portable broadband global area network system terminal, which comprises an antenna array, a closed structure and a feed network. Wherein, the antenna array is composed of a unit antenna. Supply networks of varied power distributions feed each unit antenna to get better main lobe directivity and avoid radiation zero arising from equal power feeding. In addition, a closed structure for strip-line feeding and power division network restricts impact due to spurious radiation of the power division network on the antenna directivity. Besides, an L-shaped bar feeding structure integrated with the feeding and power division network avoids structure discontinuity and processing complexity due to traditional coaxial feeding. Two points realize orthogonal feeding and right-hand circular polarization thus reducing processing deviation. A multipoint grounding structure is adopted to realize excellent impedance matching of the feeding and power division network. The antenna has the advantages of lower cost, light weight, simple processing and superior performance.

A real-time multi-point ground resistance monitoring device is provided herein to simultaneously monitor ground resistances of different work stations. The present invention mainly contains a number of monitoring ports connected to multiple test ground points in parallel via conductive wires respectively. Each monitoring port is configured with a safety range of acceptable ground resistances and a presentation manner of the alarm when the measured ground resistance of a monitoring port exceeds the safe range. The monitoring device has a self-correction function to automatically offset the resistance of conductive wire from the measurement result when the conductive wire is too long. The monitoring device can further contain a network interface allowing remote operation and monitoring.

The invention discloses a high-voltage cable metal outer sheath grounding loop current on-line monitoring system, and solves the technical problem that a power cable cannot be effectively detected inreal time. The high-voltage cable metal outer sheath grounding loop current on-line monitoring system comprises a front-end remote terminal unit and an integrated monitoring center server, and the front-end remote terminal unit and the integrated monitoring center server establish wireless communication connection with each other through a global system for mobile communication (GSM), code division multiple access (CDMA) or general packet radio service (GPRS). Compared with the prior art, the high-voltage cable metal outer sheath grounding loop current on-line monitoring system is advantaged in that the amplitude and variable quantity of the loop current of each cross-connect subsection of an operating high-voltage cable metal outer sheath is monitored in real time, valid data is remotelytransmitted to the integrated monitoring center server for statistics, analysis and warning, on-line real-time monitoring of a high-voltage cable metal sheath multipoint grounding fault is achieved, manpower is effectively saved, the working efficiency is improved, fault risks are discovered early, power failure frequency is reduced, and the high voltage power cable can reliably operate.

The invention relates to a monitoring system, and especially relates to an antitheft type multifunctional wireless high-voltage cable sheath grounding current monitoring system. The system comprises a monitoring system, an acquisition system, a grounding box, a cable anti-cut-theft alarm and current transformers, wherein the acquisition system is respectively connected with a high-voltage cable A phase, a high-voltage cable B phase and a high-voltage cable C phase through the current transformers and the cable anti-cut-theft alarm , the high-voltage cable A phase, the high-voltage cable B phase and the high-voltage cable C phase are respectively connected with the grounding box through the cable anti-cut-theft alarm and the current transformers, the acquisition system is connected with the grounding box through the cable anti-cut-theft alarm, and the acquisition system sends information to the monitoring system through a wireless network. According to the invention, cable main insulation aging or defects, oversheath multipoint grounding faults, cross interconnection connection errors, direct grounding failure, protection grounding short circuits and grounding box thefts can be discovered, network nodes are regularly detected, and link faults are automatically diagnosed.

The invention relates to a detection device for one-point grounding of a voltage transformation secondary circuit N600. The detection device comprises a signal generator and a detector which are respectively arranged in a detection device casing. The invention also relates to a detection method for the one-point grounding of the voltage transformation secondary circuit N600. According to the detection method, a standard current signal is injected in a voltage transformation secondary circuit N600 network during operation; when one-point grounding of the voltage transformation secondary circuit N600 network only occurs, the magnitude of the standard current signal is consistent with the known grounding point current detected by a detector; when multi-point grounding of the voltage transformation secondary circuit N600 network occurs, the standard current is shunted; and at the same time, the magnitude of the standard current signal is inconsistent with the known grounding point current detected by the detector, and thereby two or more grounding points are judged. The detection device and method disclosed by the invention have the advantages that the one-point grounding condition of the voltage transformation secondary circuit N600 network during operation can be quickly, conveniently and safely checked and the grounding position of the voltage transformation secondary circuit N600 network is searched.

A real-time multi-point ground resistance monitoring device is provided herein to simultaneously monitor ground resistances of different work stations. The present invention mainly contains a number of monitoring ports connected to multiple test ground points in parallel via conductive wires respectively. Each monitoring port is configured with a safety range of acceptable ground resistances and a presentation manner of the alarm when the measured ground resistance of a monitoring port exceeds the safe range. The monitoring device has a self-correction function to automatically offset the resistance of conductive wire from the measurement result when the conductive wire is too long. The monitoring device can further contain a network interface allowing remote operation and monitoring.

The invention aims at disclosing a system and implementation method for monitoring grounding current of a transformer core on line. The method comprises the following steps: analyzing data acquired by a fast Fourier transform algorithm (FFT), converting a time domain signal into a frequency domain signal, and then sequentially calculating power frequency signal amplitude values and harmonic wave amplitude values; then carrying out analysis processing by the system according to the effective values of the power frequency signal amplitudes and the effective values of the harmonic wave amplitudevalues in a current signal to determine power frequency current values and harmonic wave current values in the grounded transformer core at the moment, thus users can determine whether the transformer core is subject to multipoint grounding. The invention has the advantages that field data copy can be realized conveniently by means of an output module, and field system parameters can be set by means of a display module and a keyboard module, so that field data can be acquired conveniently and system parameters can be set under the condition of communication interrupt or inconvenient communication line installation, thus debugging and installation can be carried out conveniently, and the purpose of the invention is realized.

The invention discloses a test method and tester for multi-point grounding of a common loop. The invention has the following beneficial effects: connecting a constant-current source and an alternating current ammeter in parallel between an N wire to be tested and a ground point and using a clip-on ammeter to measure the branch current of the N wire to be tested and the ground point to change the current value of the constant-current source and comparing the current of the alternating current ammeter I1 with the current of the clip-on ammeter I2 to judge whether the N wire to be tested undergoes multi-point grounding. The method and the tester can directly detect whether the common loop undergoes multi-point grounding without exiting from the original ground point, and are simple and convenient to operate and friendly and intuitive in interface. The method and the tester can be widely applied to power field operation and detection.

The invention relates to the technical field of fault detection, and provides a grounding fault detection device and method. The device comprises a first detection module, a second detection module and a controller, one terminal of the first detection module is connected with a grounding electrode of a photovoltaic generation system, the other terminal of the first detection module is connected tothe ground, the first detection module comprises a first controllable switch and a first current detection unit connected in series, one terminal of the second detection module is connected with a non-grounding electrode of the photovoltaic generation system, the other terminal of the second detection module is connected to the ground, the second detection module comprises a second controllable switch and a second current detection unit, and the controller is used for determining whether grounding faults exist at a DC side before grid connection and at a DC side and an AC side during grid-connected operation of the photovoltaic generation system according to a first sampling current detected by the first detection module and a second sampling current detected by the second detection module and sending an alarm signal if yes. According to the grounding fault detection device, multi-point grounding faults of the photovoltaic generation system can be realized, and the operation securityof the system is guaranteed.

The invention relates to a non-contact multi-point grounding detection method and system for a secondary circuit of a current transformer. A changing magnetic field is exerted on a neutral line in a secondary circuit; on the basis of Faraday's law of electromagnetic induction, whether a current is generated in the neutral line is determined; and only when two-point grounding occurs at the secondary circuit is the current generated in the neutral line. And if only one-point grounding occurs at the loop, no current is generated. The system comprises: a signal injection system, which is used for exerting a changing magnetic field perpendicular to the neutral line in the neutral line; a signal acquisition device, which is used for collecting the current of the neutral line; and a data processing and grounding criterion system, which is used for determining whether multi-point grounding occurs. According to the invention, the method and the system can be applied to a transformation substation for determination of current transformer secondary circuit multi-point grounding examination; and on the premise that normal running of the protection device is ensured to be not influenced, whether multi-point grounding occurs at the secondary circuit of the current transformer can be effectively detected.

The invention relates to a measuring device for multi-point grounding resistance. The device comprises a generating device, a receiving device, a control device, an analyzing processing device, a display device and a communication device, wherein the generating device is connected with the control device; the receiving device is connected with the analyzing processing device; the grounding device is connected with a grounding point to be measured through a conductor; the communication device is connected with the control device; the analyzing processing device is connected with the display device. According to the measuring device, impact current is charged to a grounding loop and acquired and analyzed; the potential risk of grounding of the grounding point to be measured can be detected without excavating to damage the working environment; the impact grounding resistance can be accurately and reliably measured, and the updating and other functions can be achieved.

The invention provides an online monitoring method of multipoint earthing of a clamping piece of a transformer, which is characterized by series-connecting a device in an earthing net wire of the clamping piece. The device comprises a current transformer, an ammeter, an adjustable resistor and a full metal jacket. The ammeter is series-connected on the secondary side of the current transformer. The ammeter range has double-layer scales. The adjustable resistor is series-connected on the primary side of the ammeter. The current transformer, the ammeter and the adjustable resistor are all installed in the full metal jacket, and a window for observing the current is only reserved. A housing of the device is singly earthed. The indicated number of the ammeter is observed, and if the earthing current flowing through the clamping piece of the transformer exceeds 100mA, the adjustable resistor is adjusted to enable the current to reach the value displayed when the transformer runs normally. The invention can timely and accurately monitor the state of the clamping piece of the transformer in real time and simultaneously adjust the current-limiting resistance according to the earthing current after the clamping piece is earthed in multipoint so as to control the current flowing through the clamping piece to achieve the aim of protecting the transformer.

The invention discloses a detecting method for multipoint earthing of a voltage second loop neutral conductor network. The method comprises the steps: selecting at least one current injecting point from the voltage second loop neutral conductor network, and injecting a first current from the at least one current injecting point; detecting a current near a permanent earth point in the voltage second loop neutral conductor network to obtain a second current; comparing a difference value of the second current and the first current with a preset threshold value, and if the difference value is within the preset threshold value, confirming that the multipoint earthing exists in the voltage second loop neutral conductor network; and positioning each earthing point according to a topological structure of the voltage second loop neutral conductor network. The invention further discloses a detecting system for the multipoint earthing of the voltage second loop neutral conductor network. According to the scheme, whether the multipoint earthing exists in the voltage second loop neutral conductor network or not can be detected.

The invention discloses a PT secondary circuit online N-line multipoint ground fault detection method and device. The method comprises the following steps: both of the jaw of a first split core type current transformer (CT1) and the jaw of a second split core type current transformer (CT2) are installed on a common circuit N600(an) of the PT secondary circuit, wherein the secondary winding of the first split core type current transformer is serially connected with an adjustable resistor (Rw); the resistance of the adjustable resistor (Rw) is adjusted so as to be changed according to a preset time-resistance curve, and a first time-current curve of the secondary winding induced current of the second split core type current transformer is recorded synchronously; the first time-current curve is compared with the preset time-resistance curve, if the change modes of the two curves tend to be the same, then an N-line multipoint ground fault is judged to exist in the PT secondary circuit, or else, no N-line multipoint ground fault is judged to exist in the PT secondary circuit. According to the invention, advantages of safety, reliability and high efficiency can be realized.

The invention discloses a transformer core multi-point earthing fault testing device. The device mainly comprises a transformer, a fault simulation module, a communication conversion module, a computer and a box. A transformer core is a wound core, an excitation winding is wound on the core, 12 earthing wires are led out from different positions in the core and connected with the fault simulation module, instructions are sent out through the computer, and the on-off state of a relay on the fault simulation module is controlled through the communication conversion module so as to be connected or disconnected with the ground. Multi-point earthing fault testing of the core at different positions can be conducted, the amplitude of faulty current is monitored, and influences of ground resistance on fault conditions are researched. The testing device is simple in structure, accurate and reliable in detection, convenient to operate and very suitable for on-site application.

The invention discloses a real-time online measurement system and a real-time online measurement method for the resistance of a ground wire. The measurement system comprises a microprocessor module, an interference source processing module, a communication module, a ground wire resistance measurement software module, a power management module, a constant current source injection module, a sampling voltage reading module and an interference source acquisition module, wherein the sampling voltage reading module measures sampling voltage under the control of the microprocessor module; and the ground wire resistance measurement software module calculates the resistance of the ground wire according to the sampling voltage measured by the sampling voltage reading module under the control of the microprocessor module. The resistance of the ground wire at a single point or a plurality of points can be measured on line in real time, the system is arranged at one time, and is time-saving and labor-saving, and high accuracy is maintained; the resistance of an auxiliary current electrode and the voltage of an interference source can be measured, the system and the method also have a real-time online function, data can be transmitted to a monitoring center for monitoring, and an alarm can be given according to settings; and in addition, the system and the method have a function of diagnosing the disconnection of an external connecting wire.

The invention provides a multipoint earth fault detection method, device and system for a secondary current circuit. The method includes the steps that N-phase currents of an N-phase line of a three-phase current circuit and ground line currents of a ground line are collected in real time through a current mutual inductor, and the amplitude and the phase of the 1-kth harmonic of the N-phase currents and the amplitude and the phase of the 1-kth harmonic of the ground line currents are respectively calculated, wherein whether the amplitude of any harmonic, lager than a fault threshold, exists in the amplitude of the 1-kth harmonic of the N-phase currents is judged; if the harmonic exists, whether the amplitude of the harmonic is equal to the amplitude of the corresponding harmonic of the ground line currents and whether the difference between the phase of the harmonic and the phase of the corresponding harmonic of the ground line currents is 180 degrees are further judged; if the amplitude of the harmonic is equal to the amplitude of the corresponding harmonic of the ground line currents and the difference between the phase of the harmonic and the phase of the corresponding harmonic of the ground line currents is 180 degrees, it is judged that multipoint earth faults exist in the secondary current circuit.

The invention provides an online monitoring device and a monitoring method of multipoint earthing of an iron core of a transformer. The device comprises a current transformer, an ammeter and an adjustable resistor, which are installed in a housing. The ammeter is series-connected on the secondary side of the current transformer. The ammeter range has double-layer scales. The adjustable resistor isseries-connected on the secondary side of the ammeter. The device is series-connected in an earthing wire of the iron core and the housing of the device is singly earthed. When the iron core is earthed in multipoint, the adjustable resistor is adjusted according to the earthing current, the current flowing through the iron core is controlled and the indicated number on the ammeter is observed toenable the current to reach the value displayed when the transformer runs normally. The invention has the effects of enjoying simple structure, convenient installation, simple method and accurate andreliable monitoring, being capable of timely and accurately monitoring the running state of the iron core of the transformer in real time, achieving the aim of protecting the transformer and manufacturing the device into integrated structure so that the device is both practical and beautiful.

The invention provides an insulation fault positioning device and method applied to an insulated tubular busbar, which is based on the particularity of the segmented series connection laying of the insulated tubular busbar, uses the replacement of an original PT with a section of calibrated insulated busbar as a reference, and can effectively reduce the dielectric loss measurement error introducedby line frequency fluctuations in the online monitoring. The invention judges a dampness fault of a main insulator of each section of insulated tubular busbar by using a relative dielectric loss parameter, and judges a multi-point grounding fault of the outer sheath of each section of insulated tubular busbar by using a circulating current value. The change of the relative dielectric loss parameter of the main insulator of the insulated tubular busbar and the change of the circulating current value of the outer sheath of the insulated tubular busbar are continuously monitored and are comparedwith preset parameter thresholds, and the location having the insulation fault is dynamically marked on an insulated tubular busbar laying line layout schematic diagram; therefore, the fast and accurate positioning of the insulated tubular busbar insulation fault is realized.

The invention relates to a transformer iron core multipoint grounding diagnosis and processing method. The transformer iron core multipoint grounding diagnosis and processing method is technically characterized by comprising the steps of measuring grounding current of a transformer iron core, checking whether a measuring method is correct or not and performing re-measurement if the grounding current exceeds standard, making a definite diagnosis on failure cause through oil chromatography testing and grounding current change, taking a series resistance or large current impact treatment measure if re-measurement is abnormal, and timely arranging major repair according to a transformer operation state under the necessary situation. The transformer iron core multipoint grounding diagnosis and processing method is reasonable in design, and the problems of accurate judgment and quick processing after multiple-point grounding of a transformer occurs are solved. The analysis time of technicians is remarkably reduced, the accuracy of an analysis conclusion and timeliness of problem handling are improved, safe and stable operation of the transformer and a power grid is ensured, and operation reliability of the power grid is ensured.

A secondary neutral point multipoint grounding monitoring deivce of a voltage transformer of a transformer substation comprises a one-point grounding loop connected with a secondary neutral point of the voltage transformer, wherein a single-turn through current sensor is connected onto the one-point grounding loop. The secondary neutral point multipoint grounding monitoring deivce is characterized in that an analog / digital (A / D) data conversion module is connected onto a current sensing coil; the output end of the A / D data conversion module is connected into a micro-programmed control unit (MCU) microprocessor; and an alarming circuit, an internal memory, a communication module, a power supply processing module, a liquid crystal display (LCD) module, a key operation module and a time clock signal control module are connected onto the MCU microprocessor. Compared with the prior art, the secondary neutral point multipoint grounding monitoring deivce can store current values, give alarms and transmit the current values to a remote monitoring platform when the current values surpass the preset value by monitoring and judging secondary neutral current. In addition, compared with the traditional monitoring method, unattended operation is achieved, and a large amount of time and labor force wasted in the existing monitoring process is saved.

The invention discloses multipoint earthing trouble shooting equipment for a substation voltage transformer secondary circuit. The multipoint earthing trouble shooting equipment comprises a processor, a display module and at least one pincerlike current transformer. The output end of the pincerlike current transformer is sequentially connected with a signal processing circuit and an analog-digital converter, the output end of the analog-digital converter is connected with a first input end of the processor, and a first output end of the processor is connected with the input end of the display module. According to the multipoint earthing trouble shooting equipment, specific positions where multipoint earthing faults occur in the substation voltage transformer secondary circuit can be quickly and accurately found out, thus a safe and effective finding means for multipoint earthing faults in the voltage transformer secondary circuit can be provided for multiple power generation and power supply enterprises, and safety and stability of an electric system are greatly improved. The multipoint earthing trouble shooting equipment is widely used for the field of fault detection of direct current systems.

The invention discloses an iron core grounding monitoring method and system for a power transformer. The method includes: a monitoring substation collects current signals of a power transformer iron core and a clamping element, range conversion processing and sampling processing are carried out on the current signals to obtain measurement results, and the measurement results are sent to an upper computer management system through a wireless communication module; and the upper computer management receives the measurement results and displays the measurement results, so that the operator determines whether multi-point grounding occurs at the power transformer iron core based on the measurement results. The monitoring substation carries out range conversion processing on the current signals;conversion of ranges from the milliampere level to dozens of amperes is realized automatically; and a phenomenon of measuring the milliampere-level current by using a large range is avoided, so that the resolution and precision of the measurement results are improved and thus the measurement results have high reliability. The upper computer management displays the measurement results in real time,so that the operator is able to carry out monitoring timely in a central control room.

The invention provides a device, a system and a process for detecting and positioning aluminum electrolysis cell ground faults. The device comprises a first wire, n second wires, n bridge arm impedors, (n-1) third wires, (n-1) current sensors and a voltage source, one end of each bridge arm impedor is connected with a DC bus through the first wire, each second wire correspondingly connects the other end of one bridge arm impedor with a grounding point of an electrolytic cell, and each third wire respectively connects the other ends of the two bridge arm impedors corresponding to the two adjacent electrolytic cells and is correspondingly provided with a current sensor. Therefore, the real-time current amplitude and the phase data of each third wire can be detected, and a fault of one or more electrolytic cells can be accurately detected and positioned. According to the invention, a single-point fault and a multi-point grounding fault of the aluminum electrolysis cell can be timely and accurately detected and positioned; and the current efficiency is improved, the energy utilization rate is improved and the cost is reduced.

The invention discloses a neutral point multi-point grounding detection device based on high-accuracy detection current. The neutral point multi-point grounding detection device comprises an analyzer, a detector and a clamp meter, wherein a fault analysis module is formed by the analyzer and the clamp meter when in connection, and a fault positioning module is formed by the detector and the clamp meter when in connection. The analyzer adopts a detection current generator designed according to node shunt principle, wherein the detection current generator can achieve high linearity and significantly improve the accuracy of detection. The neutral point multi-point grounding detection device is wide in applicable scenarios and convenient to apply, for example, can be used for judging multi-point grounding of a secondary loop of a current transformer inspected by a transformer substation, and effectively detects whether multi-point grounding of the secondary loop of the current transformer occurs on the premise of ensuring that normal operation of a protective device is not affected.

The invention introduces a movable aerial earth wire direct current ice melting system, which is formed by connecting a movable power supply car (1), a wiring box (3) and an aerial earth wire (4) in series through a cable (2). The output end of the movable power supply car (1) is connected with the input end of the wiring box (3), and the output end of the wiring box (3) is connected with the input end of the aerial earth wire (4). The system has the advantages of 1) being capable of adjusting matching impedance of the earth wire to melt ice; 2) being capable of adjusting current and reducing earth wire damage; 3) being capable of melting ice through multiple segments at multiple points; 4) being capable of moving equipment to the scene at any time; (5) reducing labor intensity of construction implementation; 6) resolving complex problems of power supply obtaining, aerial earth wire segmentation, multi-point grounding and the like; 7) improving ice removing environment and reducing risks; 8) being capable of removing ice in electrifying mode and avoiding trouble of power failure; and 9) having no effect on other construction and operation based on the earth wire.

The invention relates to an insulation and voltage resistance experiment method of an electrolytic direct current system. A rectifier unit consists of a rectifier cabinet A and a rectifier cabinet B; output positive busbars of the rectifier cabinets A and B are connected with each other in parallel, and output negative busbars of the rectifier cabinets A and B are connected with each other in series; the output ends of the positive busbars, connected with each other in parallel, of the rectifier cabinets A and B are connected with the positive electrode end of an electrolysis compartment by cables, and are also connected with a first fuse by cables; the other end of the first fuse is connected with a first air switch, and the other end of the first air switch is connected with the positive electrode end of the electrolysis compartment; and the output ends of the negative busbars, connected with each other in series, of the rectifier cabinets A and B are connected with one end of a second fuse by cables, the other end of the second fuse is connected with a shunt, the other end of the shunt is connected with a second air switch, and the other end of the second air switch is connected with the grounding end of the electrolysis compartment. According to the method, the ground insulation of the electrolytic direct-current system can be mastered, grounding faults of the system can be found and treated in time, and multipoint grounding after power transmission can be prevented so as to avoid damage to equipment and human bodies.

The invention discloses a detection device for multi-point earthing fault of a small bus N600. The detection device is composed of a constant-current signal generator (A), a signal sampler (B) and a signal analyzer (C) which are connected in the electric loop manner. The constant-current signal generator (A) generates square signals of 5mA, 20mA, 100mA and 200mA and injects the same into the small bus N600; the signal sampler (B) receives and samples the square signals of 5mA, 20mA, 100mA and 200mA which are generated from the constant-current generator (A) and send the same to the signal analyzer (C) to judge whether or not the multi-point earthing fault occurs. The detection device has the advantages that synchronizing signal current measurement is adopted, earthing correctness of the earthing loop N600 is determined through judgment of two currents, thus earthing correctness and validity of the loop N600 of the transformer substation is effectively detected during operation, various interference signals are prevented, judgment is accurate, false alarm is avoided, and earthing fault is eliminated.