Zero line live-line fault detection method and detection device

Abstract

The invention relates to the technical field of zero line detection, in particular to a zero line live-line fault detection method and device. The current measuring assembly is used for measuring A-phase current, B-phase current, C-phase current and N-phase current flowing through the cable; the unbalance degree between the A, B and C three-phase current and the N-line current is calculated, and electric leakage or cable damage faults are judged; and moving the current measurement assembly, measuring A, B, C and N phase currents, analyzing the current difference of each phase at different positions, and judging the cable breakpoint position. The main control processor is used for receiving the A, B, C and N phase currents measured by the current measurement assembly, carrying out calculation and analysis and judging a fault occurrence point; and the storage unit is used for recording A-phase, B-phase, C-phase and N-phase current values of each measurement position, storing historical measurement data and carrying out subsequent analysis. Compared with a traditional electroprobe detection method, operation and maintenance personnel do not need to have a professional technical background, a complex judgment process is not needed, an operator does not need to make contact with an alternating current line, the detection efficiency can be greatly improved, and the personnel safety risk can be greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of neutral line detection, and in particular to a method and a device for detecting neutral line live fault. Background Art

[0002] With the popularization of modern industrial and civil electrical equipment, the safe operation of low-voltage power distribution systems is of vital importance. However, the abnormal situation of neutral line electrification often occurs in low-voltage power distribution systems, which may lead to a series of serious consequences, including electric shock, equipment damage, production accidents, etc. Therefore, timely detection and resolution of neutral line electrification faults is crucial to ensure personal and equipment safety and maintain normal production.

[0003] The commonly used method for detecting live neutral line faults in the industry mainly relies on "electric pen detection". Although this method is simple and easy to use, it also has many shortcomings. The operator needs to detect the circuits in the power distribution system one by one and make inferences and judgments to locate the fault point. It is time-consuming and laborious. It relies on manual experience to make judgments, which is easily affected by the operator's technical level, resulting in misjudgment or missed judgment. The operator needs to touch the AC line for detection, which poses a risk of electric shock, especially when the neutral line is live, which is more dangerous.

[0004] Therefore, a method and a detection device for detecting live neutral line faults are needed to improve detection efficiency and safety, reduce operation difficulty, and effectively reduce potential safety hazards to meet the needs of the existing environment. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract of the specification and the title of the invention of this application to avoid blurring the purpose of this section, the abstract of the specification and the title of the invention, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above-mentioned existing technologies, there are problems that electric pen detection is time-consuming and laborious, relies too much on manual experience, and touches the AC line for detection, which poses a risk of electric shock, especially when the neutral line is energized, which is more dangerous.

[0007] Therefore, the technical problem to be solved by the present invention is to design a neutral line live fault detection method and detection device that improves detection efficiency and safety, reduces operation difficulty, and effectively reduces safety hazards to meet the needs of the existing environment.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for detecting a neutral line live fault, comprising: Current measurement component, measuring the A, B, C, and N phase currents flowing through the cable; Calculate the imbalance between the A, B, C three-phase current and the N line current to determine leakage or cable damage faults; The mobile current measurement component (100) measures the currents of the A, B, C and N phases, analyzes the difference in the currents of the phases at different positions, and determines the position of the cable breakpoint.

[0009] As an improvement of the present invention, When calculating the current imbalance, Set the current deviation value threshold; Obtain the A, B, C three-phase current values ​​(Ia, Ib, Ic) and the N line current value (In) from the current measurement component; Calculate the deviation between the A, B, and C three-phase currents and the N line current: ΔIa = |Ia - In|, ΔIb = |Ib- In|, ΔIc = |Ic - In|; The deviation values ​​are summed, ΔI = ΔIa + ΔIb + ΔIc, and ΔI is compared with the current deviation value threshold to obtain the current imbalance.

[0010] As an improvement of the present invention, When judging whether there is a fault, If ΔI is less than the current deviation threshold, the current is balanced and the system operates normally; If ΔI is greater than the current deviation threshold, the current is unbalanced, and there is a leakage or cable damage fault.

[0011] As an improvement of the present invention, When determining the fault type, If ΔIa, ΔIb, and ΔIc are all greater than the current deviation value threshold, there is a three-phase unbalanced fault; If any of ΔIa, ΔIb, and ΔIc is greater than the current deviation threshold, a single-phase leakage fault exists; If two of ΔIa, ΔIb, and ΔIc are greater than the current deviation value threshold, there is a two-phase leakage fault; If ΔIa, ΔIb, and ΔIc are all greater than the current deviation value threshold, and ΔIn is greater than 2A, there is a N-line open circuit fault.

[0012] As an improvement of the present invention, When analyzing the current difference, Move the current measurement assembly along the cable and record the A, B, C, and N phase current values ​​at each measurement location; For each measurement position, calculate the deviation between the three-phase currents of A, B, and C and the current of line N, ΔIa2 = |Ia2- In2|, ΔIb2 = |Ib2 – In2|, ΔIc 2 = |Ic2 – In2|; Analyze the changing trend of ΔIa2, ΔIb2, and ΔIc2 with the measurement position, compare the ΔIa2, ΔIb2, and ΔIc2 values ​​of adjacent measurement positions, and determine the breakpoint orientation.

[0013] As an improvement of the present invention, When determining the location of the cable breakpoint, If ΔIa2, ΔIb2, and ΔIc2 change suddenly at the measurement position, there is a cable break at that position; If ΔIa2, ΔIb2, and ΔIc2 change sharply at the measurement location, there is a cable break at that location.

[0014] If there are significant differences in the ΔIa2, ΔIb2, and ΔIc2 values ​​at adjacent measurement locations, there is a cable break between the adjacent measurement locations.

[0015] A detection device, The main control processor receives the A, B, C, and N phase currents measured by the current measurement component, performs calculations and analysis, and determines the fault occurrence point; The storage unit records the A, B, C, and N phase current values ​​at each measurement location and stores historical measurement data for subsequent analysis.

[0016] As an improvement of the present invention, A filtering component is connected between the current measurement component and the main control processor to filter out high-frequency noise and interference, retain low-frequency current signals, and improve signal accuracy.

[0017] As an improvement of the present invention, The main control processor is electrically connected to the display unit, and the display unit is connected to the main control processor for communication via an I2C bus to display measurement results and status information.

[0018] As an improvement of the present invention, The main control processor is electrically connected to the prompt unit to transmit alarm information and detection status to the user.

[0019] The beneficial effects of the present invention are: compared with the traditional "electric pen detection" method, it does not require operation and maintenance personnel to have professional technical background, does not require complicated judgment process, and does not require operators to contact AC lines, which can greatly improve detection efficiency and reduce personnel safety risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them: Figure 1 It is a structural planning diagram of the neutral line live fault detection method in the present invention; Figure 2 It is a schematic diagram of the coordination of the internal modules of the MCU in the neutral line live fault detection method of the present invention. DETAILED DESCRIPTION

[0021] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0022] Example 1 Reference Figure 1~2 , this embodiment provides a method for detecting a live neutral line fault.

[0023] First, clamp the current measurement component 100 of the present invention on the A, B, C, and N phases of the cable to be tested. The measurement range of the current measurement component 100 can be set to 5mA-100A, with an accuracy of ±0.5%. The frequency response of the current measurement component 100 is set in the range of 45Hz-65Hz, and a closed-loop Hall effect current sensor can be selected. Four sensors are set (one for each phase A, B, C, and N). The current measurement component 100 measures the current value of each phase flowing through the cable in real time. The operator observes the real-time current data through the LCD screen of the device to ensure that the current measurement component 100 is correctly installed and starts working.

[0024] The main control processor 200 receives the A, B, C, and N phase current data measured by the current measurement component 100, and then calculates the current imbalance. The specific calculation method is as follows: Assuming IA, IB, and IC are the A, B, and C phase currents respectively, and IN is the N line current, the current imbalance ΔI can be expressed as: ΔI = |(IA + IB + IC) - IN| / (IA + IB + IC) When ΔI exceeds the preset threshold, the main control processor 200 preliminarily determines that the cable may have leakage or cable damage. At this time, the device prompts the operator to pay attention through LED flashing and buzzer alarm.

[0025] The operator moves the current measurement component according to the prompts and measures the current of phases A, B, C, and N at different positions. The main control processor records and analyzes the current data of each phase and calculates the current difference through the formula. When the current difference ΔI of a phase is significantly greater than that of the other two phases, the main control processor determines that there may be a breakpoint in the cable of that phase. By comparing the current differences at different positions, the breakpoint position can be further determined.

[0026] Example 2 Reference Figure 1~2This embodiment is based on the previous embodiment, and is different from the previous embodiment in that: First, the operator sets a reasonable current deviation threshold value according to the cable specifications and usage environment. This threshold value is an important criterion for judging whether the current is balanced. For example, if the design current of the cable is 20A, we can set the threshold value to 5%, that is, the current deviation threshold value is 1A (20A * 5% = 1A).

[0027] The operator clamps the current measurement component 100 on the A, B, C, and N phases of the cable to be tested, and the device automatically obtains the A, B, and C three-phase current values ​​(Ia, Ib, Ic) and the N line current value (In) from the current measurement component 100. Then, the main control processor 200 calculates the deviation between the A, B, and C three-phase currents and the N line current, ΔIa = |Ia - In| ΔIb = |Ib - In| ΔIc = |Ic - In|, and then performs the deviation value summation ΔI = ΔIa + ΔIb + ΔIc.

[0028] If ΔI is less than the current deviation value threshold, it means that the total deviation between the A, B, and C three-phase currents and the N line current is less than the preset threshold, indicating that the system current is balanced. In this case, the system is judged to be operating normally because no significant current imbalance is detected, which usually means that there is no leakage or cable damage fault.

[0029] If ΔI is greater than the current deviation threshold, it means that the total deviation between the A, B, and C three-phase currents and the N line current exceeds the preset threshold, indicating that the system current is unbalanced. When the current is unbalanced, the system may have leakage or cable damage. At this time, further analysis is required to determine the specific type and location of the fault.

[0030] Compare ΔIa, ΔIb, ΔIc with the preset current deviation threshold. If ΔIa, ΔIb, ΔIc are all greater than the current deviation threshold, it means that there is a large imbalance between the A, B, C three-phase current and the N line current, and there is a three-phase imbalance fault. If only one of ΔIa, ΔIb, ΔIc is greater than the current deviation threshold, it means that there is a large difference between the current of only one phase and the N line current, and there may be leakage in this phase.

[0031] If two of ΔIa, ΔIb, and ΔIc are greater than the current deviation threshold, this indicates that there is a large difference between the two-phase current and the N-line current, and there may be leakage in these two phases. This situation is called a two-phase leakage fault.

[0032] If ΔIa, ΔIb, and ΔIc are all greater than the current deviation threshold, and ΔIn (N line current deviation) is greater than 2A, this indicates that there may be a circuit breaker fault in the N line. This is because a circuit breaker in the N line will prevent the A, B, and C three-phase currents from flowing back through the N line, which will increase the difference between the three-phase current and the N line current.

[0033] After the fault is determined, the cable breakpoint needs to be determined based on the change in current value. The operator moves the current measurement component 100 along the length of the cable, and measures the deviation values ​​of the corresponding points at multiple positions (e.g., position 1, position 2, position 3, etc.), ΔIa2= |Ia 2- In2|, ΔIb2 = |Ib2 – In2|, ΔIc 2= |Ic2 – In2|, analyzes the change trend of ΔIa2, ΔIb2, ΔIc2 with the measurement position, compares the ΔIa2, ΔIb2, ΔIc2 values ​​of adjacent measurement positions, and determines the location of the cable breakpoint.

[0034] If at a certain measurement location, the value of ΔIa2, ΔIb2 or ΔIc2 suddenly changes from a non-zero value to close to zero or completely zero, while other phase currents remain unchanged or change little, this indicates that there may be a breakpoint at that location. This method can be called mutation judgment.

[0035] If at a certain measurement location, the value of ΔIa2, ΔIb2, or ΔIc2 changes sharply (either increasing or decreasing), this may indicate that there is a breakpoint at that location, and this method can be called sharp change judgment. If there are significant differences in the ΔIa2, ΔIb2, and ΔIc2 values ​​at adjacent measurement positions, this indicates that the cable may have a breakpoint between the two measurement positions. This method can be called a significant difference judgment.

[0036] Through this logic, operators can effectively locate the cable breakpoint and repair it. This step is critical in the cable maintenance and troubleshooting process because it is directly related to the efficiency of fault location and repair.

[0037] Example 3 Reference Figure 1~2 This embodiment is based on the previous embodiment, and is different from the previous embodiment in that: The operator clamps the current measurement component 100 on the A, B, C, and N phases of the cable to be tested. The current measurement component starts to measure and transmits the current data to the main control processor 200 through the wire. Between the current measurement component 100 and the main control processor 200, the filter component 400 filters the current signal to remove high-frequency noise and interference, ensuring that the current signal transmitted to the main control processor is accurate and stable low-frequency current signal.

[0038] The main control processor 200 receives the filtered current signal and performs calculation and analysis, including calculating the current imbalance, determining the fault type, etc., to determine the fault occurrence point.

[0039] The storage unit 300 records the A, B, C, and N phase current values ​​at each measurement location, and stores these data and historical measurement data for subsequent analysis.

[0040] The display unit 400 is connected to the main control processor 200 through the I2C bus to communicate and display the current measurement results and status information, such as current value, fault type, etc.

[0041] If a fault is detected, the main control processor 200 will be electrically connected to the prompt unit 500 to transmit alarm information to the user through sound and light alarm or other means to inform the user of the type and status of the detected fault.

[0042] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for detecting a live neutral line fault, characterized in that: include, A current measuring component (100) for measuring the A, B, C, and N phase currents flowing through the cable; Calculate the imbalance between the A, B, C three-phase current and the N line current to determine leakage or cable damage faults; A mobile current measurement component (100) measures the A, B, C, and N phase currents, analyzes the current differences of each phase at different positions, and determines the position of the cable breakpoint.

2. The method for detecting a live neutral line fault according to claim 1, characterized in that: When calculating the current imbalance, Set the current deviation value threshold; Obtaining A, B, C three-phase current values ​​(Ia, Ib, Ic) and N line current value (In) from a current measurement component (100); Calculate the deviation between the three-phase currents of A, B, and C and the current of line N, ΔIa=|Ia-In|, ΔIb=|Ib-In|, ΔIc=|Ic-In|; The deviation values ​​are summed, ΔI=ΔIa+ΔIb+ΔIc, and ΔI is compared with the current deviation value threshold to obtain the current imbalance degree.

3. The method for detecting a live neutral line fault according to claim 1 or 2, characterized in that: When judging whether there is a fault, If ΔI is less than the current deviation threshold, the current is balanced and the system operates normally; If ΔI is greater than the current deviation threshold, the current is unbalanced, and there is a leakage or cable damage fault.

4. The method for detecting a live neutral line fault according to claim 3, characterized in that: When determining the fault type, If ΔIa, ΔIb, and ΔIc are all greater than the current deviation value threshold, there is a three-phase unbalanced fault; If any of ΔIa, ΔIb, and ΔIc is greater than the current deviation value threshold, a single-phase leakage fault exists; If two of ΔIa, ΔIb, and ΔIc are greater than the current deviation value threshold, there is a two-phase leakage fault; If ΔIa, ΔIb, and ΔIc are all greater than the current deviation value threshold, and ΔIn is greater than 2A, there is a N-line open circuit fault.

5. The method for detecting a live neutral line fault according to claim 4, characterized in that: When analyzing the current difference, Moving the current measurement assembly (100) along the cable to record the A, B, C, and N phase current values ​​at each measurement position; For each measurement position, the deviation between the three-phase currents of A, B, and C and the current of line N is calculated, ΔIa2 = |Ia 2-In2|, ΔIb2 = |Ib2–In2|, ΔIc 2 = |Ic2–In2|; Analyze the changing trends of ΔIa2, ΔIb2, and ΔIc2 with the measurement position, compare the ΔIa2, ΔIb2, and ΔIc2 values ​​of adjacent measurement positions, and determine the breakpoint orientation.

6. The method for detecting a live neutral line fault according to claim 5, characterized in that: When determining the location of the cable breakpoint, If ΔIa2, ΔIb2, and ΔIc2 suddenly change at the measurement position, there is a cable break at that position; If ΔIa2, ΔIb2, and ΔIc2 change sharply at the measurement position, there is a cable break at that position. If there are significant differences in the ΔIa2, ΔIb2, and ΔIc2 values ​​at adjacent measurement positions, there is a cable break between the adjacent measurement positions.

7. A detection device, characterized in that: The method comprises the neutral line live fault detection method as claimed in claim 6, and The main control processor (200) receives the A, B, C, and N phase currents measured by the current measurement component (100), performs calculation and analysis, and determines the fault occurrence point; The storage unit (300) records the A, B, C, and N phase current values ​​at each measurement position, and stores historical measurement data for subsequent analysis.

8. The detection device according to claim 7, characterized in that: A filtering component (300) is connected between the current measurement component (100) and the main control processor (200) to filter out high-frequency noise and interference, retain low-frequency current signals, and improve signal accuracy.

9. The detection device according to claim 7 or 8, characterized in that: The main control processor (200) is electrically connected to the display unit (400), and the display unit (400) is communicatively connected to the main control processor via an I2C bus to display measurement results and status information.

10. The detection device according to claim 9, characterized in that: The main control processor (200) is electrically connected to the prompt unit (500) to transmit alarm information and detection status to the user.

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