An electrical cabinet operating state monitoring system and method

Abstract

The application discloses an electrical cabinet operation state monitoring system and method, and relates to the technical field of electrical equipment state monitoring.The system comprises a data acquisition module, a storage module and a core processing and control module.The method comprises three independently executable function modules, namely steps S1, S2 and S3: S1, overheat discrimination of bus joint points based on temperature-current change rate ratio K, wherein the normal temperature rise caused by ambient temperature change and the overheat caused by contact resistance mutation are distinguished by calculating the jump amplitude DK and comparing the preset threshold; S2, online diagnosis of sealing performance based on temperature and humidity attenuation curve fitting, wherein the sealing deterioration degree is quantified by calculating the integral area DS of the measured humidity and the theoretical humidity; and S3, drawer unit operation foolproofing based on load current time sequence authentication.The technical problems of high false alarm rate of traditional electrical cabinets, inability to evaluate the sealing aging online and misoperation of the drawer under electricity are solved without adding new hardware.

Description

Technical Field

[0001] This invention relates to the field of electrical equipment condition monitoring and intelligent operation and maintenance technology, specifically to an operation status monitoring system for power distribution cabinets, electrical control cabinets or similar power distribution equipment. Background Technology

[0002] With the development of industrial automation and smart grids, distribution cabinets and electrical control cabinets, as core distribution nodes in power systems, directly impact production safety due to their operational reliability. Currently, existing technologies for the operation and maintenance of electrical cabinets suffer from the following technical deficiencies:

[0003] (1) False alarms due to overheating at busbar connection points:

[0004] At busbar joints, loose bolts or oxidation of the contact surface can increase contact resistance, leading to localized overheating. Current technology typically uses a single temperature threshold alarm method (setting a fixed upper temperature limit, such as 80°C). However, electrical cabinets are often outdoors or under variable load conditions. Sudden increases in ambient temperature (such as in the summer afternoon) or normal increases in load current can cause temperature sensor readings to rise, easily triggering false alarms. Maintenance personnel may become complacent after frequently handling false alarms, neglecting genuine fire hazards caused by sudden changes in contact resistance. Current technology lacks a means to decouple and identify "ambient / load-induced temperature rise" from "contact degradation-induced temperature rise."

[0005] It should be noted that, although existing technologies include thermal overload protection for electric motors... and Ratio algorithms (such as motor thermal relays) are used, but their application scenario is "cutting off the motor power supply when the heat accumulation reaches the trip threshold", which focuses on the final result of heat capacity accumulation. This algorithm cannot eliminate the interference caused by the sudden rise in ambient temperature, and it is difficult to distinguish between the temperature rise caused by changes in ambient temperature and the temperature rise caused by the deterioration of contact resistance. Therefore, it cannot be directly transferred to the scenario of detecting sudden changes in contact resistance at bus joints.

[0006] (2) Issue of cabinet sealing performance not being able to be assessed online:

[0007] Electrical cabinets operate outdoors or in high-humidity workshops year-round, causing the door sealing strips to age rapidly under ultraviolet radiation and alternating hot and cold temperatures. The diurnal temperature range causes a "thermal expansion and cold absorption" effect inside the cabinet; during the day, thermal expansion expels air, while at night, contraction draws in humid air, leading to condensation and potentially short circuits. Current technology relies primarily on periodic manual inspections (visually checking the sealing strips) or the installation of expensive precision dew point meters, which are not only costly but also fail to provide online quantitative early warning of sealing degradation trends.

[0008] (3) Physical safety hazards of accidental operation of the drawer unit while it is energized:

[0009] During maintenance of withdrawable switchgear (drawer cabinet), if the operator forcibly pulls the drawer unit from the "working position" to the "test / isolation position" while the circuit breaker is not tripped (i.e., under load), a strong arcing phenomenon will occur at the moment the moving and stationary contacts separate, which can severely burn the contacts or even cause a deflagration. The current mainstream solution is to install a mechanical five-proof interlock or electromagnetic lock, but the mechanical structure has the risk of jamming failure and cannot intelligently authenticate the essential electrical condition of "whether there is current".

[0010] While some high-end drawer cabinets are equipped with electrical interlocking functions, they all use hardware contact series connection (such as connecting the circuit breaker auxiliary contact in series with the electromagnetic lock coil circuit). Their interlocking logic is fixed, the threshold is not adjustable, and they cannot record the operation behavior history, and do not have digital, configurable intelligent error prevention capabilities. Summary of the Invention

[0011] This invention provides an electrical cabinet operation status monitoring system and method to solve the comprehensive technical problems of "high false alarm rate due to overheating", "undetectable aging of seals" and "misoperation due to energized drawers" in the background art, and to achieve the goal of improving the intrinsic safety level of electrical cabinets without relying on additional expensive hardware.

[0012] To achieve the above objectives, the present invention provides the following technical solution:

[0013] like Figure 1 As shown, an electrical cabinet operation status monitoring system includes:

[0014] Data acquisition module: Used to acquire the current signal of the electrical cabinet busbar circuit in real time. and temperature signal Obtain the air humidity signal inside the cabinet. Temperature signal And to obtain the position status dry contact signal of the drawer unit;

[0015] Storage module: Stores a database of equipment operating history, a theoretical adiabatic sealed space cooling and dehumidification model, and a bus temperature-current historical baseline model;

[0016] The core processing and control module (Programmable Logic Controller (PLC) or embedded industrial computer) integrates the following:

[0017] The first arithmetic unit is used to calculate the absolute rate of change of the temperature signal and the current signal, and to determine the bus connection status based on the ratio of the two.

[0018] The second computing unit is used to fit the temperature and humidity decay curve in the fan shutdown interval and compare it with the theoretical model to calculate the sealing performance quantification index.

[0019] The third arithmetic unit is used to receive the drawer position signal and, in conjunction with the current threshold authentication, output an operation permission command.

[0020] A method for monitoring the operating status of an electrical cabinet, such as Figure 2 As shown, steps S1, S2, and S3 are three independently executable functional modules that share the same data acquisition and storage module. They are scheduled by the core processing and control module according to a preset cycle. The execution of any one functional module does not affect the normal operation of the other modules.

[0021] Step S1, based on the temperature-current change rate decoupling overheating identification method for lap joints, such as... Figure 3 As shown:

[0022] (1) The temperature of the bus joint is synchronously collected at the preset sampling frequency. and the current flowing through the busbar .

[0023] (2) Calculate the absolute rate of change of temperature and the absolute rate of change of current .

[0024] (3) Introducing dynamic ratio = ;in This represents the instantaneous value of the bus current. The preset current weighting coefficient (preferably ranging from 0.01 to 0.05) is used. It is a preset small positive constant (preferably ranging from 0.001 to 0.01) used to prevent the K value from diverging abnormally when the denominator approaches zero.

[0025] It should be noted that the denominator is introduced in this step. The term is not used to characterize the physical quantity of heat generation. Instead, it is used for numerical normalization and stabilization of the denominator: on the one hand, to prevent different load levels from causing numerical changes. Approaching zero time The values ​​diverge abnormally; on the other hand, it causes different load segments to... The baseline values ​​are kept on the same order of magnitude, allowing uniform percentage thresholds (e.g., 150%, 200%) to be applied to full-load conditions. During steady-state operation ( When the value is approximately 0, the actual criterion for determining the value of the invention is the magnitude of the jump. The formula for its calculation is: ; in, and These are the contact resistance before and after degradation. Values ​​(i.e., baseline value and instantaneous value). and These represent the rate of temperature change before and after degradation, respectively. The above derivation shows that... It depends only on the relative change factor of the temperature change rate and is independent of the absolute value of the loop current, so there is no reverse deviation problem of "sensitivity reduction under large load".

[0026] (4) Decision logic:

[0027] Compare the current K value with the real-time output value of the historical baseline model. Compare and calculate the jump magnitude =(K- ) / ×100%;

[0028] like If the value is greater than or equal to the preset first threshold (preferably 200%), it is determined that a sudden change has occurred in the contact resistance, and an emergency warning of "loose bolts / severe oxidation" is output.

[0029] like If the resistance is greater than the preset second threshold (preferred, 150%) and less than the first threshold, it is determined that the contact resistance is deteriorating and a maintenance prompt "It is recommended to check the busbar connection point" is output.

[0030] like If the temperature rise is less than or equal to the second threshold, it is considered an acceptable temperature rise caused by normal fluctuations in ambient temperature or load.

[0031] Preferably, in step S1, when the current Less than the rated current When the temperature reaches 30%, the overheat alarm output is locked; when Greater than the preset current change rate threshold Skip this time K The value is determined and the next sampling period is waited for. If more than 3 sampling periods are skipped consecutively, an "abnormal current fluctuation" warning is forcibly output, and the overheat determination in step S1 is suspended until the current returns to stability.

[0032] Step S2, an online diagnostic method for sealing performance based on temperature and humidity decay curve fitting, such as... Figure 4 As shown:

[0033] (1) First, check whether the electrical cabinet is equipped with a fan or air conditioner-type forced ventilation equipment; if not, skip step S2 and record the status information "this cabinet does not support online sealing diagnosis"; if it is equipped, monitor the start and stop status of the fan or air conditioner in real time, and trigger the passive diagnosis timer when it is detected that it has changed from running to stopping.

[0034] (2) Record the cabinet temperature for a preset time period (preferably the first 20 minutes) after continuous recording stops. and relative humidity The attenuation change is used to generate a measured attenuation curve.

[0035] (3) Retrieve the theoretical adiabatic sealed space cooling and dehumidification model in the storage module and calculate the theoretical decay curve of temperature and humidity inside the cabinet under the same initial conditions.

[0036] (4) Judgment logic: Calculate the "integral area of ​​humidity increment" between the measured curve and the theoretical curve. .like If the cumulative threshold is exceeded within a single inspection cycle (e.g., 24 hours), the sealing strip is deemed to be aged and ineffective, and a "sealing strip replacement reminder" is generated.

[0037] Step S3, a foolproof method for drawer unit operation based on load current timing authentication, such as... Figure 5 As shown:

[0038] (1) A micro switch is installed at the operating handle of the drawer unit. The dry contact signal is used to detect in real time whether the operating handle has a pre-action signal that rotates from the "locked / closed position" to the "unlocked / open position". The pre-action signal is generated before the actual displacement of the drawer unit occurs.

[0039] (2) Once the pre-action signal is detected, immediately read the current real-time effective value of the load current of the circuit. .

[0040] (3) Decision logic: If greater than the rated current If the preset percentage (preferred, 5%) is reached, it is determined to be a loaded state. The software outputs a command to prevent unlocking of the electromagnetic lock via the communication bus and pushes a "Please disconnect the circuit breaker before operating" prompt on the human-machine interface; if If the current is below the threshold, it is considered a safe state, allowing normal operation, and the timestamp and current waveform of this operation are recorded as a digital history.

[0041] Preferably, for electrical cabinets without electromagnetic locks, the prohibition on unlocking command is replaced by issuing a continuous audible and visual alarm through the human-machine interface, and during the alarm period, sending a "drawer energized operation risk" interlock signal to the upper-level control system (such as DCS or SCADA) via the communication bus, so that the upper-level system can perform remote tripping or logical interlocking.

[0042] The present invention has the following advantages over the prior art:

[0043] (1) Extremely high anti-interference and reliability: The K-value ratio method is used to replace the single temperature threshold. The physical law (Joule heating effect) is used to distinguish between "external temperature rise" and "internal resistance temperature rise". The false alarm caused by changes in ambient temperature is eliminated from the bottom layer of the algorithm, which significantly improves the alarm accuracy.

[0044] (2) Zero-cost hardware upgrade: The sealing diagnosis does not require the addition of expensive dew point meters or humidity sensors. It fully reuses the inherent temperature and humidity sensing resources and fan control signals in the cabinet, realizing the explicit and data-driven online management of hidden faults (aging of sealing strips).

[0045] (3) Intrinsic safety and behavior traceability: The drawer operation foolproof method uses electrical quantities (current) as the final permission condition, which is more logically rigorous than pure mechanical locks. At the same time, the automatic recording of operation behavior history provides reliable data support for the "two tickets and three systems" of power safety. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the overall system module architecture;

[0047] Figure 2 This is a schematic diagram of the module scheduling and execution logic of the overall control method of the present invention;

[0048] Figure 3 This is a flowchart of an overheating detection method based on the temperature-current rate of change ratio;

[0049] Figure 4 This is a flowchart of a sealing performance diagnostic method based on temperature and humidity decay curve fitting;

[0050] Figure 5 This is a flowchart of a drawer operation foolproof method based on load current timing authentication;

[0051] Figure 6 This is a schematic diagram comparing the measured temperature and humidity decay curves with the theoretical curves for sealing performance testing.

[0052] Figure 7 This is a comparison waveform of the K value under normal fluctuation and sudden overheating conditions. Detailed Implementation

[0053] To make the technical solution of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments. It should be noted in advance that the numerical values, thresholds and time constants involved in the following embodiments are preferred examples and do not constitute a limitation on the scope of protection.

[0054] I. Specific implementation details regarding busbar overheating identification (corresponding to step S1, such as...) Figure 3 (as shown) In actual engineering implementation, the intelligent control device inside the cabinet or the multi-functional power meter is used as the hardware carrier, and the sampling rate of its processor is set to once per second. In the denominator of the value formula The item has been verified through actual testing. When the value is between 0.01 and 0.05, it can maintain a wide current range of 100A to 2000A. Baseline numerical stability. In practical engineering applications, even the loop current... The change was several times. The determination result is unaffected, proving that the feature can effectively achieve the purpose of the invention.

[0056] 1. Establishment and updating of historical baseline models:

[0057] (1) During the initial "run-in and stabilization period" (e.g., the first 7 days) of the equipment operation, the system automatically learns and stores the standard K value matrix under different load segments (e.g., 20%Ie, 50%Ie, 80%Ie) as the initial baseline database.

[0058] During the break-in and stabilization period, the system synchronously monitors the maximum rate of change of the absolute value of the busbar temperature. If the rate of change of temperature continues to exceed the preset safety range during the stabilization period (e.g., daily temperature rise exceeds 15°C), it is determined that there is a defect in the initial installation, and a prompt "Please check the torque of the busbar lap bolts" is output. The break-in and stabilization period is then extended to 14 days or a baseline is established after manual confirmation.

[0059] (2) As runtime increases, the system uses the Exponential Weighted Moving Average (EWMA) algorithm to update the baseline in real time:

[0060] ;

[0061] in The instantaneous K value at the current sampling time t:

[0062] = ;

[0063] This is the baseline value from the previous sampling time; The weighting coefficient is preferably in the range of 0.1 to 0.3, which is used to balance the sensitivity to recent data and the memory of historical normal states.

[0064] (3) When (The jump in the current K value relative to the baseline is calculated using the same formula as described in step S1, item (4), i.e.) =( - ) / If the baseline (×100%) exceeds 150% but has not yet reached 200%, temporarily freeze the baseline update (i.e., maintain the current baseline). = (The instantaneous value will not be included in the moving average. Updates will resume only after the K value recovers to 150% or below, to prevent outliers from polluting the baseline database and to avoid the failure of subsequent mutation detection thresholds.)

[0065] Similarly, when When the K value is ≥ 200%, it cannot be included in the baseline because the K value has deviated significantly from the normal range. Therefore, the baseline update remains frozen until the K value recovers to 150% or below.

[0066] 2. Supplementary conditions for mutation detection: To prevent distortion of the K value when the current approaches zero, when... <30% or The overheat alarm output is locked out if and only if ≥30% and When the current is stable, an overheat alarm is allowed to be output; if more than 3 sampling cycles are skipped consecutively, an "abnormal current fluctuation" warning will be forcibly output, and the overheat determination in step S1 will be suspended until the current stabilizes.

[0067] 3. Effect verification: such as Figure 7 As shown, in a simulation experiment where the ambient temperature suddenly rises from 25°C to 40°C, the traditional temperature sensor outputs an over-temperature alarm, while the K value of this invention remains stable and does not trigger a false alarm; however, in an experiment simulating a 50% decrease in bolt tightening torque, the K value jumps to 250% of the baseline within 20 seconds, and the system issues an early warning within 3 sampling cycles (3 seconds).

[0068] II. Specific implementation details regarding sealing performance diagnosis (corresponding to step S2, such as...) Figure 4 (as shown)

[0069] The trigger condition for executing this method is set to "the moment the fan / air conditioner stops" rather than "the system stops". The purpose is to take advantage of the environment without forced convection after the system stops to accurately capture the natural breathing infiltration effect.

[0070] 1. Theoretical Model Construction: The specific construction method of the theoretical adiabatic closed space cooling and moisture desorption model is as follows:

[0071] (1) During the factory commissioning phase of the electrical cabinet, close the cabinet door and start the fan to bring the temperature and humidity inside the cabinet to a steady state, and record the initial temperature inside the cabinet at the moment the fan stops. and the initial relative humidity inside the cabinet Simultaneously, the ambient temperature outside the cabinet was collected at the moment the fan stopped. As boundary conditions for theoretical model calculations ( Collected independently for each diagnosis, rather than using fixed calibration values.

[0072] (2) Calculate based on the Clapeyron-Clausius equation. Corresponding saturated water vapor partial pressure Then, the initial absolute moisture content inside the cabinet can be calculated. .

[0073] (3) Assume that the air inside the cabinet is cooled naturally only by the cabinet wall after the fan stops, and the temperature change with time t satisfies Newton's law of cooling:

[0074] ;

[0075] in The thermal time constant of the cabinet is obtained through prior experimental calibration. The calibration method is as follows: Before the electrical cabinet leaves the factory, close the cabinet door and start the fan to allow the temperature inside the cabinet to reach a steady state, then stop the fan and continuously record the temperature inside the cabinet from the initial temperature. Let it cool naturally until ( + Time required for ) / 2 ,but = / ln2. For electrical cabinets that have been installed but cannot be calibrated, Typical values ​​for standard-sized cabinets are 300s to 900s.

[0076] (4) Absolute moisture content inside the cabinet under sealed and insulated conditions Remain unchanged, according to Inversely calculate the saturated water vapor partial pressure at the corresponding temperature. Then, the theoretical relative humidity is calculated:

[0077] = ×100%;

[0078] in The constant of water vapor is used to generate a complete time-theoretical relative humidity decay curve.

[0079] 2. Integral area of ​​humidity increment Calculation:

[0080] ;

[0081] in This is the start time of the passive diagnostic timer triggered the instant the wind turbine stops. This refers to the measured attenuation curve of the relative humidity inside the cabinet, which is continuously recorded in step S2, item (2). (Right now The theoretical relative humidity decay curve is obtained by retrieving the theoretical model in step S2, item (3).

[0082] like Figure 6As shown, if the seal is good, the measured humidity will decrease closely following the theoretical value, and the integral area will be close to 0; if the seal is aged, external moisture will continuously replenish it, and the measured humidity will lag far behind the theoretical value, and the integral area will increase significantly.

[0083] The The preset thresholds are calibrated during the factory commissioning phase of the electrical cabinet using the following methods:

[0084] (1) Perform a complete sealing test on a newly manufactured, well-sealed electrical cabinet and calculate the resulting sealing performance. The value is denoted as the initial reference value. (This value remains unchanged throughout the entire lifespan of the equipment and serves as a fixed basis for failure determination.)

[0085] (2) The preset failure threshold is fixed as follows: ×3.

[0086] (3) In actual operation, the current measurement is automatically performed once every quarter. Value, denoted as (For trend analysis only), if If the measured value increases by more than 50% compared to the previous quarter, it indicates that "the sealing strip has aged and it is recommended to replenish the stock for replacement"; if... Exceeding the fixed failure threshold (i.e.) If the value is ×3, it is determined that the sealing strip has aged and failed, and tripping or forced shutdown protection is executed.

[0087] For operating conditions where factory calibration is not possible, the default value of the preset threshold can be set to 200%RH·min (i.e., the product of relative humidity percentage and minutes).

[0088] 3. Self-protection logic: If the calculation result shows... If the value exceeds the limit, the system will not immediately trigger a trip. Instead, it will output a maintenance work order suggesting that the sealing strip be replaced during the daytime when the atmospheric humidity is below 60%, thus avoiding blindly opening the cabinet for work on rainy days.

[0089] III. Specific implementation details regarding drawer operation error prevention (corresponding to step S3, such as...) Figure 5 (as shown)

[0090] This embodiment is mainly applied to low-voltage withdrawable switchgear of models such as GCS and MNS, where GCS and MNS are general model codes for low-voltage withdrawable switchgear.

[0091] 1. Signal Acquisition: A microswitch is added to the pivot of the operating handle on the drawer panel to detect the initial movement of the handle from the "operating / closed" position to the "open / unlocked" position. This action signal precedes the horizontal displacement of the drawer body along the guide rail by approximately 200ms to 500ms, providing sufficient time for the central processing unit (CPU) to perform current authentication. The arrival detection of the drawer body in the operating and test positions is still achieved through conventional microswitches, used to confirm the final position of the drawer, but not simultaneously serving as a trigger signal to prevent unlocking.

[0092] 2. Basis for determining the 5% threshold: Setting it to 5% of the rated current is to accurately distinguish between "capacitive induced current / transformer no-load excitation current" and "load-bearing operating current". For example, in a circuit with a rated current of 100A, if the measured current is >5A, it is determined that the lower end of the circuit breaker is definitely under load, and unlocking and pulling out is strictly prohibited; if it is <5A, it is determined that the load has been basically disconnected, and pulling out is allowed.

[0093] 3. Anti-software deadlock redundancy: When the CPU main program crashes, the authentication logic is maintained by an independent hardware comparator circuit, ensuring that the drawer remains locked by default in extreme cases of communication interruption or software freeze, which conforms to the fail-safe design principle.

[0094] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An electrical cabinet operation status monitoring system, characterized in that, include: The data acquisition module is used to acquire the current signal of the busbar circuit of the electrical cabinet in real time. and temperature signal Obtain the air humidity signal inside the cabinet. Cabinet internal temperature signal And to obtain the position status dry contact signal of the drawer unit; The storage module stores a database of equipment operating history, a theoretical adiabatic sealed space cooling and dehumidification model, and a bus temperature-current historical baseline model. The core processing and control module integrates the following: The first arithmetic unit is used to calculate the absolute rate of change of the temperature signal and the current signal, and to determine the bus connection status based on the ratio of the two. The second computing unit is used to fit the temperature and humidity decay curve in the fan shutdown interval and compare it with the theoretical model to calculate the sealing performance quantification index. The third arithmetic unit is used to receive the drawer position signal and, in conjunction with the current threshold authentication, output an operation permission command.

2. The electrical cabinet operation status monitoring system according to claim 1, characterized in that, The core processing and control module is a programmable logic controller or an embedded industrial control computer.

3. A method for monitoring the operating status of an electrical cabinet, characterized in that, The system described in claim 1 or 2 includes the following steps: Step S1, Overheating identification method for lap joints based on temperature-current change rate decoupling: The temperature of the bus lap joints is synchronously collected at a preset sampling frequency. and the current flowing through the busbar Calculate the absolute rate of change of temperature. and the absolute rate of change of current Introducing dynamic ratio = ,in The preset current weighting coefficient, A preset small positive constant; compare the current K value with the real-time output value of the historical baseline model. Compare and calculate the jump magnitude =(K- ) / ×100%; if If the contact resistance is greater than or equal to a preset first threshold, a sudden change in contact resistance is determined, and an emergency warning is output; if If the resistance is greater than the preset second threshold but less than the first threshold, it is determined that the contact resistance is deteriorating, and a maintenance prompt is output; if If the value is less than or equal to the second threshold, it is determined to be a normal fluctuation in ambient temperature or load. Step S2, Online Diagnostic Method for Sealing Performance Based on Temperature and Humidity Decay Curve Fitting: When the fan or air conditioner is detected to switch from running to stopping, a passive diagnostic timer is triggered to continuously record the cabinet temperature within a preset time after stopping. and relative humidity The attenuation change is used to generate the measured attenuation curve; the theoretical adiabatic closed space cooling and dehumidification model is retrieved to calculate the theoretical attenuation curve; the area of ​​the humidity increment integral between the measured curve and the theoretical curve is calculated. ,like If the cumulative value exceeds the preset threshold within the inspection cycle, the sealing strip is deemed to have aged and failed. Step S3, a foolproof method for drawer unit operation based on load current timing authentication: A microswitch located on the drawer unit's operating handle detects in real time the pre-action signal of the operating handle rotating from the locked / closed position to the unlocked / open position. This pre-action signal is generated before the actual displacement of the drawer unit occurs. Once the pre-action signal is detected, the current real-time effective value of the circuit's load current is immediately read. ;like greater than the rated current If the preset percentage is reached, it is determined to be in a loaded state and a command to prohibit unlocking is output; if If the current is below the threshold, it is considered a safe state and operation is allowed. At the same time, the operation timestamp and current waveform are recorded as a digital history.

4. The method for monitoring the operating status of an electrical cabinet according to claim 3, characterized in that, In step S1, the preset first threshold is 200%, and the preset second threshold is 150%; the current weighting coefficient The value range is 0.01 to 0.05, and the small positive constant is... The value range is 0.001 to 0.

01.

5. The method for monitoring the operating status of an electrical cabinet according to claim 3, characterized in that, In step S1, when the current Less than the rated current When the temperature reaches 30%, the overheat alarm output is locked; when Greater than If the K value determination is skipped, the next sampling cycle will be waited for. If more than 3 sampling cycles are skipped consecutively, an "abnormal current fluctuation" warning will be forcibly output, and the overheat determination in step S1 will be suspended until the current stabilizes.

6. The method for monitoring the operating status of an electrical cabinet according to claim 3, characterized in that, The method for constructing the theoretical adiabatic closed space cooling and moisture desorption model is as follows: During the factory commissioning phase of the electrical cabinet, the cabinet door is closed and the fan is started to allow the temperature and humidity inside the cabinet to reach a steady state. The initial temperature inside the cabinet is recorded the moment the fan stops. and the initial relative humidity inside the cabinet At the same time, the ambient temperature outside the cabinet is collected. Based on the Clapeyron-Clausius equation, calculate Corresponding saturated water vapor partial pressure Then, the initial absolute moisture content inside the cabinet can be calculated. Assuming the air inside the cabinet cools naturally only through the cabinet walls after the fan stops, and the temperature change with time t follows Newton's law of cooling. ,in The thermal time constant of the cabinet is determined by... = / ln2 calibration obtained, For the temperature inside the cabinet from Let it cool naturally until ( + The time required for ) / 2; the absolute moisture content inside the cabinet under sealed and insulated conditions. Remain unchanged, according to Inversely calculate the saturated water vapor partial pressure at the corresponding temperature. Then calculate the theoretical relative humidity. = ×100%, of which The constant of water vapor is used to generate a complete time-theoretical relative humidity decay curve.

7. The method for monitoring the operating status of an electrical cabinet according to claim 3, characterized in that, The steps described in step S2 The preset threshold is calibrated during the factory commissioning phase of the electrical cabinet in the following way: a complete sealing test is performed on a newly manufactured, properly sealed electrical cabinet, and the calculated threshold is obtained. The value is denoted as the initial reference value. This value remains constant throughout the entire lifecycle of the device; The preset failure threshold is fixed as follows: ×3; In actual operation, the current measurement is performed automatically once per quarter. The value is denoted as ,like If the measured value increases by more than 50% compared to the previous quarter, it indicates that the sealing strip has aged; if... If the fixed failure threshold is exceeded, the sealing strip is determined to have aged and failed, and tripping or forced shutdown protection is performed; for operating conditions that cannot be factory calibrated, the default value of the preset threshold is set to 200%RH·min.

8. The method for monitoring the operating status of an electrical cabinet according to claim 3, characterized in that, The preset duration in step S2 is 20 minutes, and the inspection cycle is 24 hours.

9. The method for monitoring the operating status of an electrical cabinet according to claim 3, characterized in that, The preset percentage mentioned in step S3 is 5%.

10. The method for monitoring the operating status of an electrical cabinet according to claim 3, characterized in that, In step S3, for electrical cabinets without electromagnetic locks, the prohibition on unlocking command is replaced by issuing a continuous audible and visual alarm through the human-machine interface, and during the alarm duration, a lockout signal is sent to the next higher-level control system via the communication bus, so that the next higher-level system can perform remote tripping or logical interlocking.

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