796 results about "Drain current" patented technology

The invention provides a circuit board electrical performance test and diagnosis method, which comprises the following steps of: constructing a structured process-electrical data set by collecting process parameters such as etching time, pressing temperature, drilling precision, copper foil thickness and the like and electrical test indexes such as impedance deviation, leakage current, signal attenuation and the like; screening key process variables by adopting mutual information analysis and a maximum correlation-minimum redundancy criterion; through modeling of a three-layer causal diagram and a structural equation, quantitative influence evaluation of process parameters on electrical performance and fault types is realized; when a fault is detected, the system can automatically perform reverse reasoning, identify a main manufacturing deviation item and generate attribution diagnosis and process optimization suggestions, so that the accuracy of fault diagnosis and the pertinence of process adjustment are improved, and the fault occurrence rate is reduced and the product quality is improved.

The invention particularly relates to a leakage current testing method, device and system for an intelligent circuit breaker, and relates to the technical field of electrical safety detection. A composite signal generation and injection module; a broadband signal acquisition and conditioning module; and a line fault positioning and impedance analysis module. According to the invention, the composite signal generation module realizes the non-interference isolation injection of a leakage current signal and a high-frequency positioning signal, and guarantees the high fidelity of data through adaptive filtering, multi-channel synchronous sampling and high-precision timing. The line positioning module integrates TDR and a frequency domain impedance method, and through multi-frequency point deviation correction and topology-GIS association, the fault type is accurately identified, and the test and troubleshooting period is significantly shortened.

The invention discloses a high-voltage cable operation state on-line monitoring, intelligent early warning and fault positioning system, particularly relates to the technical field of power equipment insulation monitoring, and is used for solving the problems that transient discharge signals generated in the cable insulation degradation process are difficult to effectively capture and accurate fault positioning cannot be realized in the prior art. The method comprises the following steps: collecting transient leakage current signals and traveling wave propagation characteristic parameters, performing phase correlation analysis on leakage current pulses and power frequency voltage to identify discharge types, and performing variational mode decomposition and Hilbert-Huang transform on the signals to respectively extract complexity characteristics and energy distribution characteristics; signal logic conflicts are judged by analyzing similarity and statistical distance among characteristics of a plurality of monitoring points, and collaborative diagnosis is started or traveling wave distance measurement is directly utilized to carry out insulation state evaluation and fault location. And finally, differential early warning levels are generated according to the diagnosis result, and fault line selection and positioning information is output to realize real-time monitoring, intelligent early warning and accurate positioning of the operation state of the high-voltage cable.

The invention provides a device for inhibiting drain-source overvoltage and overcurrent through active gate drive of a silicon carbide MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor), aiming at solving the problem of voltage or current overshoot caused by circuit parasitic parameters in a high-speed switching process of the SiC MOSFET and simultaneously considering the switching speed and energy loss balance. According to the device, drain-source voltage vdc and direct-current bus voltage of the SiC MOSFET are collected to serve as feedback signals, and gate driving voltage and equivalent gate resistance are dynamically adjusted; in a key stage (a Miller plateau switching-on period and a voltage rising period switching-off period) of a switch transient state, a gate resistance network is switched through a logic control circuit, and suppression of drain current overshoot and drain-source voltage overshoot is realized. Simulation verification shows that the device can reduce voltage overshoot by 20%-30% and current overshoot by 25%-60%, only a single voltage feedback channel is needed, the cost is obviously lower than that of a traditional multi-signal acquisition active gate driving scheme, and the device is suitable for a high-efficiency SiC MOSFET power converter.

The invention belongs to the technical field of direct current monitoring, and discloses a TMR-based open-close type direct current leakage current detection device, which comprises a magnetic core, one or more pairs of TMR sensors, a secondary side feedback coil and a main control circuit, and is characterized in that the magnetic core is provided with air gaps which are oppositely arranged; the TMR sensors are symmetrically arranged in the air gap; the secondary side feedback coil is wound on the surface of the magnetic core and forms closed-loop control with the main control circuit; the main control circuit comprises an acquisition feedback circuit, a secondary side detection circuit and a main control chip, the acquisition feedback circuit acquires signals of the TMR sensor under the control of the main control chip, generates feedback current and inputs the feedback current to the secondary side feedback coil, and the secondary side detection circuit is connected between the secondary side feedback coil and the main control chip. And the main control chip collects the secondary side voltage of the secondary side detection circuit and calculates to obtain the direct current leakage current. According to the invention, direct current leakage current detection with high sensitivity, low drift and strong anti-interference capability is realized under the open-close structure, and the requirements of a modern electric power system on continuity, safety and maintainability are met.

The invention relates to the technical field of on-line health monitoring of wide bandgap semiconductor power devices, and discloses an on-line gate leakage current monitoring method and system for a GaN power device, and the method comprises the steps: extracting an average gate driving current which is within a complete switching period, an average value of instantaneous currents flowing into or out of the gate of the GaN power device; and on the basis of the average gate driving current, gate leakage current is obtained, so that online gate leakage current monitoring of the GaN power device can be carried out. The system corresponds to the method. According to the invention, the core problem that the traditional voltage detection method is insufficient in resolution and cannot realize early warning is fundamentally solved; meanwhile, a source electrode series sampling and non-intrusive signal conditioning circuit is adopted, a switch and a voltage stabilizing circuit are prevented from being introduced into a grid electrode driving loop, and therefore interference on parasitic parameters of the grid electrode loop is eliminated, and feasibility and reliability of application in a high-frequency and high-sensitivity GaN power device are ensured.

The invention relates to a power transmission line fault risk grading evaluation method based on multistage early warning, and belongs to the field of power system safety. Comprising the following steps: acquiring an insulator surface pollutant data generation matrix; extracting spatial distribution characteristics of pollutants; leakage current waveforms under different humidity are calculated; extracting a leakage current harmonic component and pulse characteristics; dividing pollution flashover risk grades; matching the maintenance strategy and generating an equipment scheduling instruction; and performing fault risk grading evaluation to generate a report. According to the method, through multi-source data fusion and dynamic modeling, accurate evaluation and preventive maintenance of the pollution flashover risk of the insulator are realized, and the safety and reliability of a power system are improved.

The invention discloses a full-power variable-speed pumped storage unit stator winding insulation state online monitoring method, and provides a high-capacity generator unit stator winding insulation state online monitoring method which can be applied to a network side transformer neutral point ungrounded system. According to the method, an effective common-mode monitoring loop can be established, and monitoring is carried out by utilizing the third harmonic of the motor stator winding and is not interfered by the high-frequency switch harmonic of the frequency converter. In order to solve the problem that a full-power variable-speed pumped storage unit generally has large capacity and is not easy to realize online measurement, the invention provides a method for measuring on a neutral point outgoing line, which can realize online measurement of the insulation state of a stator winding when the load current is relatively large. The method is suitable for a full-power variable-speed pumped storage high-capacity unit, leakage current measurement can be carried out under the condition of large load current, and stator insulation information online monitoring is achieved.

The invention discloses a method for monitoring the insulation state of a stator winding of an injection unit based on neutral point harmonic frequency sweeping. The invention provides an active online monitoring method based on harmonic injection for stator winding insulation of a full-power variable-speed pumped storage unit. A common-mode loop is constructed for a motor stator winding of a network side transformer neutral point ungrounded system through a motor neutral point grounded transformer, and therefore online monitoring of the insulation state of a motor stator is achieved. In order to solve the measurement problem of the full-power variable-speed pumped storage unit under the large-current working condition, a neutral point outgoing line current detection technology is adopted. A machine end large current interference area is avoided, monitoring is carried out on the primary side of the grounding transformer, transmission errors are avoided, and the measurement precision and reliability of insulation monitoring signals are remarkably improved. According to the invention, harmonic injection is carried out by avoiding an inherent common-mode component of a unit, a monitorable leakage current signal is enhanced, and the accuracy of insulation equivalent capacitance calculation is ensured.

The invention relates to an on-line monitoring method for the on-off state and abnormal behavior of a synchronous rectification MOSFET of a power system. According to the method, a drain-source voltage VDS signal and a drain current Isd signal of a synchronous rectification MOSFET are collected in the working process of a system, and on-line monitoring is conducted on the on-off state and the abnormal state of the MOSFET. The method specifically comprises the following steps: conducting state monitoring: when VDS is smaller than or equal to a conducting judgment threshold value, judging to be conducted, and otherwise, judging to be turned off; monitoring an oscillation state, and judging switch oscillation when the VDS generates multiple complete oscillations in a set time window; early turn-off monitoring is carried out, early turn-off is judged according to whether I sd is higher than a threshold value or not during turn-off in the DCM mode, and early turn-off is judged according to the current descending trend and zero intersection point deviation in the CCM mode; withstand voltage monitoring: when the VDS transient peak value exceeds the rated withstand voltage or margin of the device, determining that the device is unsafe; and mis-opening monitoring: in the DCM mode, when the VDS is close to the opening threshold value during the logic turn-off period, determining that the mis-opening risk exists. The method can improve the reliability of the power supply system.

The invention discloses a generator stator winding single-phase earth fault positioning method, system and device and a medium, and the method comprises the steps: enabling three phases of a generator stator winding to be connected in series end to end to form a series loop; low-frequency voltage pulses are injected into the three-phase winding, and a fault phase is determined by comparing symmetry damage characteristics of tail-end current by adopting a tail-end current vector analysis method; injecting a low-frequency voltage pulse into the current phase winding, detecting the current difference between the head end and the tail end of each parallel branch, identifying a branch with abnormal leakage current by combining a leakage current characteristic analysis method, and determining a fault branch; establishing a high-frequency distribution parameter model, and performing high-frequency voltage pulse injection positioning for multiple times to obtain three independent high-frequency pulse positioning results; and performing weighted fusion on the three independent high-frequency pulse positioning results, and performing optimization by using an intelligent optimization algorithm to obtain an optimized single-phase earth fault position. According to the invention, the accuracy and rapidity of fault diagnosis and positioning can be improved.

A high-frequency resistant ground fault circuit interrupter (HF-GFCI) with self-test and end-of-life detection is disclosed. The invention incorporates a noise-resistant fault detection circuit, an auto-test module, and an end-of-life shutdown mechanism to ensure reliable protection. The device minimizes false tripping due to high-frequency noise and enhances safety through continuous self-monitoring. Experimental validation confirms improved immunity to leakage currents and transient voltage disturbances. The HF-GFCI also provides an LED circuit having dual functionality: an LED indicator circuit and neutral to ground detection on the load side of the HF-GFCI.

The invention discloses a transformer substation AC power supply residual current detection method and device, and the method comprises the steps: carrying out the vector synthesis of three-phase current data and zero line current data, forming a current difference sequence, exporting a residual current reference curve, and carrying out the fluctuation analysis of the residual current reference curve, and judging the leakage characteristics. After effective leakage features are formed through harmonic elimination, dominant frequency components are locked through frequency spectrum decomposition; calibrating a leakage type identifier according to the dominant frequency component and forming segmented leakage distribution; a deviation degree is formed by means of segmented leakage distribution and residual current reference curve deviation analysis, a correction deviation value is formed through load fluctuation compensation, and a standard exceeding coefficient is formed according to threshold value comparison to detect abnormal nodes to form hidden danger data; establishing a judgment rule based on the hidden danger data and the leakage type identifier to form a detection evaluation index; and executing path tracking on the detection evaluation indexes to form leakage position information, forming a disposal priority through intensity analysis to generate a residual current detection report, and realizing leakage current classification identification and self-adaptive evaluation.

The invention relates to the technical field of multi-column lightning arresters, in particular to a multi-column lightning arrester parallel matching method, which comprises the following steps of S1, performing aging screening and energy tolerance testing on zinc oxide resistor discs of the same batch; s2, measuring the direct-current reference voltage Uref of the resistor discs, the leakage current I0 under 0.75 Uref, the impact residual voltage UL under the lightning wave and the operation residual voltage US under the operation wave one by one; s3, screening the resistor discs for three times; and S4, high-low matching is carried out by taking the operation residual voltage US as a main matching basis, so that the operation residual voltage deviation of each column of series resistor disc group is smaller than a first preset value, and the direct current reference voltage numerical value deviation is smaller than a second preset value. The strict screening process ensures the consistency of the performance of the resistor discs, and the reasonable grouping mode makes the electrical performance of each column resistor disc group more balanced, thereby achieving the effect of improving the operating wave endurance capability and the current sharing characteristic of the multi-column lightning arrester, and reducing the probability of faults caused by uneven current distribution of the MOV.

The invention discloses a modeling method of a simulation model, a storage medium and a terminal. The method comprises the following steps: acquiring an initial simulation model of a semiconductor device to be modeled; according to the initial simulation model, fitting a drain current-grid voltage characteristic curve of a sub-threshold region of the semiconductor device to be modeled; judging whether the to-be-modeled semiconductor device has subsurface leakage current in a subthreshold region of the drain current-grid voltage characteristic curve or not; if the secondary surface leakage current exists, establishing a sub-circuit model representing the secondary surface leakage current; integrating the sub-circuit model and the initial simulation model; and according to the integrated initial simulation model, fitting the drain current-grid voltage characteristic curve of the sub-threshold region until the fitting curve of the drain current-grid voltage characteristic curve converges, and obtaining a simulation model of the semiconductor device to be modeled. According to the modeling method, the secondary surface leakage current can be accurately modeled, and the simulation precision and accuracy of an integrated circuit simulation model are improved.

The utility model provides a test system for a power device, and the system comprises power equipment which is used for applying high-voltage excitation between a source electrode and a drain electrode of the power device; the semiconductor parameter analyzer is used for applying bias voltage to the grid electrode of the power device; the oscilloscope is combined with the current probe to measure the drain current of the power device; and the upper computer is used for controlling the working time sequence of the power supply equipment and the semiconductor parameter analyzer so as to realize the scanning test of the device parameters. By combining the high-voltage power supply, the oscilloscope and the general semiconductor parameter analyzer, the performance of the power device under different voltage and current conditions can be comprehensively evaluated, the reliability and stability of the device in practical application are ensured, and the test cost is also considered.

A motor leakage current detector and / or a heat compensating circuit, devices using same and related methods are disclosed herein. Included are a uniquely wired current transformer to allow for polarity agnostic leakage current detection, a leakage current detector using same and having a notifier to alert a user. In other forms, an accessory power cord and power strip are disclosed capable of detecting early motor failure conditions. In still other forms, other machinery failure early warning systems are disclosed as are numerous motor operated devices using same including without limitation pumps.

The utility model discloses a leakage current detection type PCBA test circuit and equipment. The leakage current detection type PCBA test circuit comprises a test current signal output unit, a test voltage signal output unit and a test result signal output unit, the test current signal output unit is used for outputting a leakage current detection current signal; the test current signal output unit is provided with a current adjusting circuit, and the current adjusting circuit is used for adjusting the value of the leakage current detection current signal. The test voltage signal output unit is used for outputting a leakage current detection voltage signal; the test voltage signal output unit is provided with a voltage adjusting circuit, and the voltage adjusting circuit is used for adjusting the value of the leakage current detection voltage signal. The leakage current detection current signal and the leakage current detection voltage signal are used for being loaded to a PCBA to be detected; when the PCBA receives the leakage current detection current signal and the leakage current detection voltage signal, a leakage current protection signal is output; the test result output unit is configured to output a test result signal when the leakage current protection signal is received.

The invention relates to a method for monitoring the running state of a lightning arrester for a power grid high-voltage cable terminal tower, which comprises the following steps of: firstly, collecting the running data of the lightning arrester in real time, preprocessing the collected data and carrying out time-space synchronous calibration on the collected data, and then calculating the running state of the lightning arrester based on a cable coupling coefficient and an interphase coupling coefficient; the method comprises the following steps of: firstly, correcting the influence of spatial distribution interference and electromagnetic interference on data according to the pre-processed data, so as to establish a correlation analysis model, then, generating a personalized early warning threshold value by utilizing a dynamic threshold value algorithm based on historical operation data and operation age limit of equipment, and carrying out abnormity judgment on the data subjected to pre-processing and time-space synchronization calibration through the early warning threshold value. And finally, based on a correlation analysis model, carrying out coupling analysis on a lightning arrester leakage current signal and a cable circulation current signal in the extracted data, and outputting and uploading a monitoring report. The method has the advantages of being accurate in early warning and capable of achieving multi-dimensional monitoring.

The invention discloses a full-automatic life test system for an isolation device, which belongs to the field of reliability test of semiconductor devices, and comprises a system host used for providing a test environment and bearing a plurality of test channels; the high-low voltage isolation conversion module is arranged corresponding to each test channel and is used for switching between a high-voltage aging loop and an insulation resistance measurement loop of each channel; the real-time leakage current monitoring module is used for continuously monitoring the leakage current of each isolation device in the high-voltage aging process; the precision measurement and data acquisition module is used for carrying out insulation resistance measurement on the isolation device in a measurement mode; the central control and software system module is respectively connected with the high-low voltage isolation conversion module, the real-time leakage current monitoring module and the precision measurement and data acquisition module, and the central control and software system module is used for automatically triggering and controlling an insulation resistance measurement process according to leakage current data, judging the state of a device according to a measurement result, and outputting the state of the device. And aging and stopping of the test channel are managed.

The invention relates to the technical field of electrical insulation detection, in particular to a composite insulation on-line monitoring method and device used in the running state of a middle-high voltage motor. According to the method, key parameters such as low-frequency alternating-current leakage current, voltage response characteristics and insulation resistance change values are synchronously collected through a modular monitoring terminal in the operation process of a motor, and a multi-parameter diagnosis vector is constructed by combining low-frequency leakage current analysis and direct-current excitation measurement technologies; and feature extraction, comparative analysis and health level evaluation are carried out by using an edge computing terminal, so that four-level classification of the insulation state is realized. The matched device comprises a monitoring terminal, a data communication module, an edge computing intelligent terminal and an industrial-grade touch display module, has the functions of local storage, breakpoint resume, authority management and the like, can be widely applied to operation maintenance and fault early warning of a middle-high voltage motor, and improves the operation safety and the operation and maintenance intelligent level of equipment.

The invention relates to the technical field of electrical fault detection, in particular to an online fault judgment and automatic detection method for a marine cable, which comprises the following steps of: acquiring ground leakage current and load current in operation, extracting an active component of the leakage current and analyzing the nonlinear correlation between the active component and the load current to realize online early warning of insulation degradation; when the ship is in a working condition of allowing short-time power failure of partial non-critical loops, positioning a fault branch based on a normalization result of the ground capacitance variation before and after the power failure of each branch and the cable length; after power supply is recovered, the fault type is judged by combining the leakage current fundamental wave and phase voltage phase difference and the harmonic distortion rate; during power-off maintenance, high-frequency carrier waves are injected, the position of a fault point is determined according to current attenuation abnormity, correction is carried out by combining temperature and vibration factors, and the detection accuracy and the positioning precision are improved.

The invention relates to the technical field of power system state monitoring, and discloses an insulator defect detection method and device and a storage medium, and the method comprises the steps: collecting the leakage current of an insulator, and constructing a polarity conduction screening model through power frequency phase information, so as to generate a composite current sequence which highlights the polarization attribute of an interface; analyzing the nonlinear degree of the attenuation rate of the sequence drifting along with evolution time in a multi-stage diffusion evolution time domain, and generating an interface electrochemical mass transfer composite index; utilizing the index to invert and construct an interface polarization background reference and stripping the interface polarization background reference from the composite current sequence so as to extract an abnormal discharge pulse residual error; and finally, quantizing the pulse form distortion degree of the residual error, and performing suppression normalization operation on the distortion degree by using the index to output a judgment result. According to the invention, the interference of the interface mass transfer process is effectively eliminated, and the specific detection of the pollution flashover hidden danger is realized.

The invention relates to the technical field of power system monitoring and anomaly analysis, and discloses a museum power distribution loop abnormal power consumption mode identification method and system. The method comprises the following steps: acquiring millisecond-level current and voltage original waveforms of each level of power distribution loop of a museum, and extracting a time sequence current sequence containing harmonic distortion rate mutation and leakage current high-frequency pulses; performing exhibition area portrait classification based on the sequence, and determining dominant load type labels of each loop; fusing the load label and the time sequence, and predicting a normal current track of each loop; collecting a latest current waveform in real time, comparing the latest current waveform with the predicted trajectory, and identifying and marking a potential abnormal loop; abnormal source equipment combination judgment and abnormal millisecond-level evolution characteristic analysis are carried out on the abnormal loop; and judging whether to trigger instant early warning or not according to the abnormal evolution characteristics and the equipment combination type. According to the invention, accurate identification and source positioning of abnormal power utilization of the distribution loop of the museum are realized, the false alarm rate is reduced, and the timeliness and reliability of abnormal response are improved.

The invention relates to the technical field of intelligent power distribution network safety detection and fault processing, in particular to a multi-source coupling leakage current accurate traceability and cooperative suppression method and system for a power distribution network, and the method comprises the steps: collecting leakage current, voltage phase and power fluctuation data through a synchronous phasor measurement device; based on the collected data, constructing a four-dimensional feature library, carrying out decoupling processing on leakage current signals, and then realizing accurate traceability positioning of the leakage current according to a matching result of the leakage current signals and the four-dimensional feature library and a time difference between sensors; data are uploaded to a distribution network dispatching center, leakage current is evaluated based on a dynamically adjusted safety threshold value, and then operation states of a photovoltaic inverter, an energy storage converter and a charging pile are cooperatively controlled to realize active suppression of the leakage current; and performing preliminary diagnosis on the leakage current at the edge side, uploading a result to a cloud end, and determining a final diagnosis conclusion. According to the invention, the accuracy of multi-source coupling leakage current tracing and the accuracy of cooperative suppression of the power distribution network are improved.

The invention discloses a traction motor bearing fault online detection method and system, a medium and equipment. The method comprises the steps that S1, a working condition signal and a leakage current signal of a traction motor under a stable working condition are acquired; s2, performing adaptive decomposition on the leakage current signal, and capturing a sensitive mode corresponding to the state change of the bearing, namely a corresponding high-frequency mode component of the traction motor bearing in the leakage current signal; s3, extracting a peak-to-peak value Apeak of a main wave crest in the high-frequency modal component time domain waveform, a fluctuation period Ta, a resonant frequency fc of a high-frequency modal component frequency spectrum and energy Ef corresponding to the resonant frequency fc; and S4, inputting the Apeak, Ta, fc, Ef and working condition signals into a pre-constructed and trained bearing fault multi-feature fusion diagnosis model, and outputting a motor bearing diagnosis result. The method has the advantages that the fault features of the motor bearing can be effectively and sensitively obtained, and accurate traction motor bearing fault early warning is achieved.

The invention relates to the technical field of state monitoring, in particular to an optical storage device state monitoring method and system based on an FPGA. The method comprises the following steps: acquiring FPGA structure data; deploying a ring oscillator unit in an FPGA idle logic resource area based on the FPGA structure data, and configuring a leakage current measurement channel on an FPGA programmable I / O pin to obtain leakage current measurement channel configuration data; acquiring RO oscillation frequency data and grid leakage current data according to the leakage current measurement channel configuration data; and performing mapping calculation on the RO oscillation frequency data and the grid leakage current data based on a preset temperature calibration curve and a voltage calibration curve. Through high-precision real-time monitoring and multiple regression modeling based on the FPGA, the diagnosis precision and intelligent early warning capability of the temperature and stress of the key area of the optical storage equipment are effectively improved, and the problem that a traditional monitoring system is insufficient in accuracy, real-time performance and pertinence is solved.

The invention relates to an electric leakage alarm method and device for a resident end, equipment and a medium. The method comprises the following steps: acquiring a leakage current signal, performing low-pass filtering processing on the leakage current signal, and then calculating a leakage current effective value; dynamically calculating an alarm threshold according to the environment parameter information; the leakage current effective value is compared with an alarm threshold value, grading event judgment is carried out according to a comparison result and waveform characteristic parameters of the leakage current signal, and an alarm trigger mark is generated; according to the alarm triggering mark, generating an alarm instruction to execute at least one of the following response actions: driving a piezoelectric buzzer and an LED to generate a sound-light alarm signal; and generating alarm information according to the alarm triggering mark, and uploading the alarm information to a monitoring platform. According to the method, through leakage current signal filtering processing, dynamic alarm threshold calculation and a grading alarm mechanism, the accuracy and environmental adaptability of electric leakage detection in a residential electricity consumption scene are improved, and the intelligent level of electricity consumption safety monitoring is improved.

The invention relates to the technical field of electrical safety monitoring, in particular to a leakage protection system for a low-voltage IT power supply system. Comprising an impedance spectrum identification unit used for constructing an original spectrum data set; calculating a system-to-ground complex impedance spectrum based on the original spectrum data set; a parallel RC equivalent circuit model is applied to decouple the real insulation resistance and the system ground capacitance based on the system ground complex impedance spectrum; the dynamic evaluation unit is used for constructing an insulation health index; calculating a system structure change factor; the trend prediction unit is used for calculating an insulation aging rate based on a time sequence formed by historical real insulation resistance data; the comprehensive risk decision-making unit is used for calculating a comprehensive risk index; and outputting a tripping signal in response to the insulation health index exceeding a preset final protection limit value. The problem of false alarm caused by the fact that a traditional protection device cannot distinguish resistive leakage current and capacitive leakage current is solved, and the protection accuracy is remarkably improved.

The invention discloses a low-voltage cabinet and an operation environment monitoring and early warning system thereof, and belongs to the technical field of low-voltage electrical equipment monitoring. The system comprises an information acquisition module, an electromagnetic environment analysis module, an in-cabinet environment analysis module, an operation activity analysis module, a temperature-leakage current analysis module and a flow rate optimization module. A plurality of environmental coefficient and collaboration models are constructed by collecting various indexes such as electromagnetism, gas, air pressure, operation frequency and the like, temperature and leakage current thresholds are dynamically calibrated, and the air velocity in the cabinet is optimized based on a temperature-leakage current collaboration coefficient and an operation activity coefficient. The system can comprehensively sense the operation state of the low-voltage cabinet, achieves precise early warning and intelligent ventilation, and effectively improves the operation safety and energy efficiency level of equipment.