A low voltage CT automatic verification low voltage CT wiring fault monitoring device and method

Abstract

The application discloses a kind of low voltage CT automatic verification low voltage CT wiring fault monitoring device and method, it is related to the technical field of fault analysis and detection of mutual inductor automatic verification assembly line, the device is arranged in the secondary wiring component of secondary wiring mechanism in low voltage CT automatic verification assembly line, comprising: information acquisition module, for real-time acquisition displacement electric signal of the end of measuring rod terminal in secondary wiring component;Signal measurement and control terminal, for processing displacement electric signal, according to the displacement information obtained and the preset displacement range comparison, judge whether there is wiring fault, to carry out wiring fault early warning and the collection of corresponding station wiring fault image;Video image monitoring host computer, for using pre-stored image recognition model, identify the mode and state of wiring fault in image.The application can realize real-time, accurate fault detection and alarm to the wiring state of the secondary side terminal of the measured mutual inductor in assembly line, optimize the efficiency and quality of assembly line detection.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fault analysis and detection of automatic calibration pipeline of transformers, and particularly relates to a low-voltage CT wiring fault monitoring device and method in low-voltage CT automatic calibration. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] A low-voltage current transformer (CT) is an important supporting measurement element in various low-voltage power complete sets to realize corresponding measurement, control and electric energy metering functions, and its performance directly relates to the accuracy of measurement and metering and the reliability of protection device action. Therefore, whether in the production stage or in the acceptance stage, the transformers need to be compulsorily detected / calibrated. At present, low-voltage CT batch automatic calibration pipelines have been put into operation, and the currently operated pipeline systems are similar. With continuous high-load operation of the systems, the deficiencies in detection capacity, operation efficiency, calibration quality and efficiency are gradually revealed. For example, the transformer detection items involved in automatic calibration include insulation resistance measurement and power frequency voltage withstand test, secondary winding turn-to-turn insulation strength test, basic error measurement test and the like. The test procedures are complex and the control procedures are complicated. In the long-term high-load operation process, the performance of the pipeline control equipment will degrade or even fail. Once a fault or inaccuracy occurs, it may cause calibration misjudgment, metering accidents or trade disputes. Therefore, real-time online detection and early warning analysis of faults of the low-voltage CT automatic calibration pipeline are of great significance to the optimization design of the transformer pipeline, the improvement of pipeline calibration efficiency and reliability.

[0004] In the low-voltage CT pipeline calibration process, the fault that occurs with a relatively high probability is the wiring fault of the secondary wiring terminal of the pipeline to the secondary wiring terminal of the transformer. At present, the monitoring of the secondary side wiring fault of the transformer is divided into two categories:

[0005] One is that after the fault occurs, the electrical parameters are monitored to be abnormal by project calibration and electrical measurement and control system, at which time the calibration system judges and prompts the wiring fault. However, this fault monitoring method is lagging behind, which will consume the test time of the voltage withstand test unit or the error calibration unit for implementing the calibration of the 12 workstations of the simultaneously calibrated transformers. In addition, the re-calibration operation after the fault is found will also reduce the calibration efficiency to a certain extent, and this method cannot effectively define the specific reason for the fault.

[0006] Secondly, after the fault occurs, the electrical measurement and control system does not monitor the abnormality, at this time, the test parameter abnormality or blank information may be determined as unqualified by the test system, thereby causing the misjudgment, and although the repeated detection and confirmation of the unqualified mutual inductor can be used to identify the connection fault, this fault monitoring method is more lagging, and the repeated operation will inevitably cause the waste of the test time of the corresponding measured mutual inductor, and finally affects the pipeline test efficiency and test rhythm.

[0007] Therefore, at present, further reliability optimization design needs to be implemented for the low-voltage CT automatic test pipeline, and the connection fault of the terminal of the secondary side of the low-voltage CT in the pipeline is monitored and alarmed in time and accurately, so as to realize the reliability growth of the pipeline. SUMMARY

[0008] In order to solve the above problems of the prior art, the present application provides a low-voltage CT automatic test low-voltage CT connection fault monitoring device and method, a low-voltage current transformer secondary side terminal connection fault monitoring device is added in the corresponding unit of the low-voltage CT automatic test pipeline, and the technologies in multiple fields such as sensor test, computer control, digital image processing and machine learning are combined, so that real-time and accurate fault detection and alarm of the terminal connection state of the secondary side of the measured mutual inductor in the pipeline are realized, and the efficiency and quality of the low-voltage CT pipeline test are optimized.

[0009] In a first aspect, the present application provides a low-voltage CT automatic test low-voltage CT connection fault monitoring device.

[0010] A low-voltage CT automatic test low-voltage CT connection fault monitoring device is arranged on a secondary connection assembly of a secondary connection mechanism in a low-voltage CT automatic test pipeline, and comprises:

[0011] An information acquisition module comprises a differential transformer type linear displacement measurement sensor, which is used for acquiring a displacement electric signal of a terminal end of a measuring rod in the secondary connection assembly in real time;

[0012] A signal measurement and control terminal is used for processing the acquired displacement electric signal, generating displacement information, comparing the displacement information with a preset displacement range, judging whether there is a connection fault, and performing connection fault early warning and acquisition of a connection fault image of a corresponding work station according to the judgment result;

[0013] A video image monitoring host is used for identifying the mode and state of the connection fault in the image by using a pre-stored image recognition model according to the acquired connection fault image, and synchronizing the identification result to a control host of the pipeline.

[0014] Further technical solutions, for low-voltage CT automatic calibration pipeline insulation withstand voltage test station and error calibration station, in the secondary wiring mechanism of the station, the secondary wiring assembly is provided with a low-voltage CT wiring fault monitoring device;

[0015] In the process of insulation resistance measurement and power frequency withstand voltage test, secondary winding turn-to-turn insulation strength test, magnetic saturation margin measurement and basic error measurement of the pipeline, the low-voltage CT wiring fault monitoring device is used to monitor the real-time secondary side wiring terminal wiring fault of the low-voltage current transformer.

[0016] Further technical solutions, the information acquisition module further comprises a sensor clamping mechanism, the sensor clamping mechanism is assembled on the secondary wiring assembly, and is used for fixing the linear displacement measuring sensor.

[0017] Further technical solutions, the information acquisition module adopts a three-section differential transformer type linear displacement measuring sensor and a sensor clamping mechanism matched with the sensor;

[0018] The linear displacement measuring sensor comprises a primary coil, two secondary coils, a coil backbone, an iron core, a connecting rod and a test cable;

[0019] The skeleton of the coil backbone is a three-section I-shaped cylinder, the primary coil and the two secondary coils are wound on the skeleton of the coil backbone, the two secondary coils are symmetrically distributed on both sides of the primary coil and reversely connected in series to form a differential phase connection; the skeleton of the coil backbone is internally provided with a hollow cylindrical space, a movable cylindrical rod-shaped iron core is arranged at the middle position of the hollow cylindrical space, the iron core is fixedly connected with the iron core connecting rod below the iron core through welding, the other end of the iron core connecting rod is fixedly connected with the upper end of the measuring rod in the secondary wiring assembly through a sleeve coupling, forming an iron core movable transformer type linear displacement measuring sensor; the test cable is connected with the primary coil and the two secondary coils for signal transmission.

[0020] Further technical solutions, the sensor clamping mechanism comprises a sleeve coupling, an adjusting washer, a guide sleeve, a support shaft sleeve, a mounting top cover, a mounting bolt, a sensor protection shell and a wire bundler;

[0021] The adjusting washer is mounted between the top end of the guide sleeve and the body of the secondary wiring assembly, the bottom end of the guide sleeve is provided with a mounting positioning tooth, and the mounting positioning tooth is assembled with the positioning tooth hole on the upper end surface of the coil backbone to prevent the sensor from rotating circumferentially; the sensor is assembled with the mounting top cover through the support shaft sleeve, and the mounting top cover is fixed on the body of the secondary wiring assembly through the mounting bolt; the sensor is externally sleeved with the sensor protection shell, and the wire bundler is used for fixing the test cable.

[0022] Further technical solutions, the iron core adopts high magnetic permeability, high strength, high magnetic induction intensity of strong magnetic material, the iron core connecting rod adopts non-magnetic stainless steel material, the sensor protection shell adopts weak magnetic material.

[0023] Further technical solutions, the information collection module adopts LT20 linear displacement measurement sensor and sensor clamping mechanism matched with the sensor;

[0024] The inductive coil and signal conditioning assembly of the LT20 linear displacement measurement sensor are assembled in the stainless steel metal shell, the iron core is placed in the cylindrical hole at the bottom of the shell, and the upper end of the measuring rod of the secondary wiring assembly is connected through threads;

[0025] The sensor clamping mechanism includes a sleeve, a sleeve upper end cover, an upper shaft sleeve, a lower shaft sleeve, a fastening screw and a small compression spring; wherein the sleeve and the sleeve upper end cover are detachably assembled in a nested manner, the sleeve upper end cover is provided with a compression spring, and an adjusting pad is arranged between the compression spring and the body of the secondary wiring assembly; the sleeve is cylindrical at the upper end and has a two-prong type at the lower end, the two prongs at the lower end of the sleeve are arranged in a 180-degree direction and cross-assembled with the two clamping bases of the lower shaft sleeve; the lower shaft sleeve is fixed on the body of the secondary wiring assembly through the fastening screw; the small compression spring is clamped between the spring pressing part of the secondary wiring mechanism and the stainless steel shell of the sensor.

[0026] Further technical solutions, the stainless steel metal shell of the LT20 linear displacement measurement sensor is fixedly connected with the upper shaft sleeve and the lower shaft sleeve through interference fit, the upper shaft sleeve and the lower shaft sleeve are gap-fitted with the cylindrical inner wall of the sleeve, and the signal test line in the secondary wiring assembly is led out through the wiring slot hole of the lower shaft sleeve.

[0027] Further technical solutions, the signal measurement and control terminal comprises:

[0028] The excitation signal generation module is used to generate the sine wave excitation signal required to drive the linear displacement measurement sensor;

[0029] The signal conditioning module is used to receive the displacement electric signal collected by the sensor and to demodulate and amplify the signal;

[0030] The drive amplification module is provided with AD8065 in-phase proportional amplification circuit and AD8065 voltage follower, which are respectively used to perform signal amplification and voltage offset conditioning;

[0031] The analog-to-digital conversion module is used to convert the processed analog signal into a digital signal;

[0032] An ARM control subsystem is configured to convert the received digital signal into displacement information, compare the displacement information with a preset displacement range, determine whether a wiring fault exists, and generate and issue a wiring fault control instruction;

[0033] A monitoring alarm module is configured to alarm a wiring fault;

[0034] A video image acquisition module is configured to start a camera to acquire a wiring fault image of a corresponding station according to the wiring fault control instruction;

[0035] A picture transmission module is configured to transmit the acquired image to a video image monitoring host.

[0036] In a second aspect, the application provides a low-voltage CT wiring fault monitoring method in low-voltage CT automatic verification.

[0037] A low-voltage CT wiring fault monitoring method in low-voltage CT automatic verification uses the low-voltage CT wiring fault monitoring device in the first aspect to monitor a secondary wiring process in a low-voltage CT automatic assembly line verification process in real time, including:

[0038] The secondary wiring assembly goes down, the wiring end in the assembly contacts a secondary side wiring terminal of a low-voltage CT to be tested, and a displacement electrical signal of the wiring end is acquired in real time;

[0039] After the acquired displacement electrical signal is signal-conditioned and analog-to-digital converted, displacement information is obtained, and whether a wiring fault exists is determined according to a comparison between the displacement information and a preset displacement range;

[0040] When it is determined that a wiring fault exists, a fault early warning is started, and acquisition of a wiring fault image is simultaneously started;

[0041] According to the acquired wiring fault image, a fault mode and a state are identified using an image recognition model, and the identification result is synchronously transmitted to an HMI detection monitoring control host and a unit control execution layer in the assembly line.

[0042] The above one or more technical solutions have the following beneficial effects:

[0043] 1. In view of the secondary side terminal connection fault of the low-voltage CT in the automatic pipeline calibration, the application provides a low-voltage CT connection fault monitoring device and method in the automatic calibration of the low-voltage CT, the device integrates transformer calibration technology, precision instruments, automation technology, computer science and technology and other technical means, by adding the low-voltage current transformer secondary side terminal connection fault monitoring device in the corresponding unit of the low-voltage CT automatic calibration pipeline, the real-time and accurate fault detection and alarm of the secondary side terminal connection state of the measured transformer in the pipeline can be realized, the efficiency and quality of the low-voltage CT pipeline calibration are optimized, the device is simple, easy to operate, universal and low in cost, and the device is added to the existing pipeline calibration system, which is convenient for improving the operation efficiency of the transformer calibration pipeline and is conducive to realizing the reliability growth of the pipeline.

[0044] 2. The application can provide early warning at the first time when the connection fault occurs, facilitate immediate processing and avoid time waste caused by lagging monitoring by collecting the position information of the terminal head in real time through the differential transformer type displacement sensor; according to the preliminary fault monitoring result based on displacement, the image acquisition is started as needed, and the storage pressure of the monitoring equipment and the pipeline operation and maintenance cost are reduced by collecting the image at regular intervals when there is no fault; the fault mode is identified by combining the machine vision technology and the machine learning method, the misjudgment is reduced, and the accuracy of fault judgment is improved; the device can be integrated with the existing low-voltage CT automatic calibration system to realize the reliability growth of the pipeline and improve the calibration efficiency.

[0045] 3. The transformer secondary side terminal connection fault monitoring device can be used as an auxiliary measuring means of the magnetic switch in-place detection function of the existing pipeline, the on-site early warning of the secondary side terminal connection failure of the measured transformer is started by using the sound and light alarm function of the monitoring device, the on-site staff can be reminded in real time to stop loss in time, so that the subsequent project calibration test time of the corresponding measured transformer is saved, the misjudgment probability is reduced, and the low-voltage CT pipeline optimization has a positive role and practical significance.

[0046] The advantages of the additional aspects of the application will be partially given in the following description, partially become obvious from the following description, or be known by the practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0047] The drawings accompanying the specification of the application are used to provide further understanding of the application, the illustrative embodiments of the application and the description thereof are used to explain the application, and do not constitute improper limitation on the application.

[0048] Figure 1 The calibration process schematic diagram of the low-voltage CT automatic calibration system to which the connection fault monitoring device is added in the embodiment of the application;

[0049] Figure 2 The topological structure diagram of the low-voltage CT automatic detection system to which the wiring fault monitoring device is additionally connected in the embodiment of the present application is shown in the figure.

[0050] Figure 3 The mechanical structure diagram of the secondary wiring mechanism of the low-voltage CT automatic detection system in the embodiment of the present application is shown in the figure. (a) is the overall structure diagram, and (b) is the front view.

[0051] Figure 4 The wiring state diagram of the secondary wiring assembly of the pipeline test bench and the secondary side wiring terminal of the transformer in the embodiment of the present application is shown in the figure. (a) is the front view, (b) is the side view, (c) is the schematic diagram of the collection device, (d) is the schematic diagram of the pole falling state I, (e) is the schematic diagram of the pole falling state II, (f) is the schematic diagram of the pole falling state III, and (g) is the schematic diagram of the pole falling state IV.

[0052] Figure 5 The principle diagram of the wiring fault monitoring device in the embodiment of the present application is shown in the figure.

[0053] Figure 6 The mechanical structure and principle diagram of the information collection module in the wiring fault monitoring device in the embodiment of the present application is shown in the figure. (a) is the mechanical structure cross-sectional diagram, (b) is the cross-sectional diagram of the sensor part, and (c) is the principle diagram of the sensor sensing.

[0054] Figure 7 The improved sensor and clamping mechanism of the information collection module in the wiring fault monitoring device in the embodiment of the present application are shown in the figure. (a) is the front view, (b) is the side view, (c) is the A-A cross-sectional diagram, and (d) is the sleeve fork comb diagram.

[0055] 1, tool tray; 2, transformer to be tested; 3, secondary wiring assembly; 4, wiring fault monitoring device; 5, profile; 6, cylinder sliding table; 7, guide rod sliding block; 8, magnetic induction switch; 9, drag chain; 10, collection device.

[0056] 21, secondary side wiring terminal; 211, embedded nut; 212, wiring bolt; 213, spring washer; 214, flat washer; 215, primary conductor.

[0057] 31, measuring rod; 311, lower bushing; 312, upper bushing; 32, secondary wiring terminal; 33, screw; 34, pre-insulated wiring terminal; 35, bolt; 36, test wire; 37, spring assembly; 371, compression spring; 372, adjustment pad; 373, spring compression part; 38, locking screw.

[0058] 41, information acquisition module; 411, linear displacement measurement sensor; 4111, signal wire slot hole; 4112, primary coil; 4113, secondary coil; 4114, coil keel; 4115, iron core; 4116, iron core connecting rod; 4117, insulation layer; 4118, test cable; 412, sensor clamping mechanism; 4121, sleeve coupling; 4122, adjusting washer; 4123, guide sleeve; 4124, support shaft sleeve; 4125, installation top cover; 4126, mounting bolt; 4127, sensor protection shell; 4128, wiring assembly body; 4129, wire bundler; 41211, sleeve upper end cover; 41212, sleeve; 41213, upper shaft sleeve; 41214, lower shaft sleeve; 41215, small compression spring; 41216, fastening screw;

[0059] 42, signal measurement and control terminal; 421, excitation signal generation module; 422, signal conditioning module; 423, drive amplification module; 424, analog-to-digital conversion module; 425, ARM control subsystem; 426, monitoring and alarm module; 427, video image acquisition module; 428, image transmission module; 429, RS485 level conversion module; 430, voltage conversion module; 43, video image monitoring host. DETAILED DESCRIPTION

[0060] It should be noted that the following detailed description is exemplary only and is intended to provide further description of the present application, and is not intended to limit the exemplary embodiments according to the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. In addition, it should also be understood that when the terms "comprise" and / or "include" are used in the present specification, there is a presence of the features, steps, operations, devices, components and / or combinations thereof.

[0061] Example One

[0062] The embodiment provides a low-voltage CT wiring fault monitoring device in low-voltage CT automatic verification, and the device is realized through the implementation scheme and the mechanical structure design of the low-voltage CT wiring fault monitoring device of the secondary wiring terminal of the low-voltage current transformer in the low-voltage CT automatic verification assembly line, the position information of the secondary wiring terminal is collected based on the operation principle of the linear variable differential transformer, then the signal is regulated, information is transmitted, and the signal is controlled and processed, finally, the system control monitoring alarm module performs the over-limit early warning, and the video image acquisition module acquires the fault image information of the corresponding work position of the measured transformer, and the machine vision, digital image processing and machine learning method are used to realize the fault mode recognition in the video image of the corresponding work position of the measured transformer. Through the above device, not only can the first-time monitoring early warning be provided when the wiring fault occurs, so that the fault can be processed immediately, but also the video image acquisition can be started synchronously when the fault occurs, so that the storage pressure of the monitoring equipment caused by the continuous acquisition of the work position image can be reduced to a certain extent, the acquisition is started under the condition and the acquisition is performed regularly under the condition, thereby the assembly line operation and maintenance cost is reduced, and necessary data information is provided for subsequent reliability analysis management.

[0063] Firstly, as shown in the figure, the verification process of the existing low-voltage CT automatic verification system mainly includes a pretreatment unit, a feeding unit, an identification and positioning unit, a conveying unit, an insulation resistance measurement and power frequency withstand voltage test unit, a secondary winding interturn insulation strength test unit, a magnetic saturation margin measurement and basic error measurement unit, a sorting and labeling unit, a discharging unit and a post-processing unit. Figure 1 Based on the above hardware design, the automatic assembly line project verification function setting mainly includes a buffer area, a test unit (i.e. a test work position), a test device and a control subsystem, wherein the buffer area is used for buffering the feeding tray to improve the verification efficiency; the test work position is composed of wiring, disconnection and adjustment positioning mechanism and the like, and is used for automatic disconnection and positioning adjustment of the transformer; the test device is used for verification of the transformer detection projects, including tests of the transformer interturn, error, magnetic saturation and demagnetization projects; and the control subsystem realizes automatic and manual control of the measurement work position.

[0064] For the above assembly line process, the transformer secondary side wiring terminal wiring fault monitoring device is additionally arranged at the insulation resistance measurement and power frequency withstand voltage test unit, the secondary winding interturn insulation strength test unit, the magnetic saturation margin measurement and basic error measurement unit of the insulation withstand voltage test work position (i.e. the insulation resistance measurement and power frequency withstand voltage test unit) and the error test work position (i.e. the error test work position) of the assembly line, so as to realize real-time monitoring of the transformer secondary side wiring terminal wiring fault in the above insulation withstand voltage test and error test process, as shown in the figure. Figure 1

[0065] ​Secondly, for the above-mentioned low-voltage CT automatic pipeline detection system of the added wiring fault monitoring device, in order to realize the wiring fault monitoring function, the software design of the system is also optimized, such as Figure 2 As shown in the figure, the software part of the low-voltage CT automatic detection system mainly includes detection system management software, detection software and control software. The detection system management software is responsible for task management, action coordination between the detection conveying system and the detection device, information interaction between the detection system and the background monitoring and scheduling platform, obtaining detection data and uploading detection results to the background monitoring and scheduling platform. The detection software is responsible for the control of the mutual inductor detection device, and cooperates with the detection distribution system to complete the detection task. The control software is responsible for the control of the mechanical action of each functional unit of the low-voltage CT detection system and the monitoring of the state of each functional unit, and cooperates with the detection system to complete the detection of the low-voltage CT.

[0066] Further, the monitoring and control of the detection system is composed of three layers of architecture, including the background monitoring and scheduling management layer, the detection monitoring management layer and the unit control execution layer. The unit control execution layer controls the test equipment or execution components of different stations through PLC and ARM respectively, receives the monitoring and logical judgment of various sensor or control button signals, controls the actions of actuators, indicator lights and electromechanical mechanisms according to program logic, realizes the logical judgment and timing control required by the program, and the corresponding control information is transmitted to the HMI detection monitoring control host through the MODBUS bus. In this embodiment, the project detection information of the two voltage withstand test units and the three comprehensive error detection units of the detection system is communicated with the HMI detection monitoring control host through the RS485 bus. Each test unit of the project detection is provided with 12 detection stations, and under full load operation, 1000 mutual inductors can be detected every eight hours on average. Preferably, the voltage withstand test unit and the error detection unit of the pipeline system can be designed in one body, and the insulation voltage withstand test and the basic error test can be sequentially performed on the same station according to the timing control; or they can be designed in a split type, and the insulation voltage withstand test and the basic error test are respectively completed on the voltage withstand test table and the error test table.

[0067] In addition, the HMI detection supervision management layer executes corresponding production monitoring management according to the unit measurement and control state and result transmitted by the control execution layer. Its functions mainly include obtaining detection tasks, monitoring detection states, communicating with test devices through RS485 interface to obtain measurement data of mutual inductors, switching to manual control when detection line fails or manual detection is needed, single-step controlling each station operation, and transmitting each unit state to the background monitoring and scheduling management layer through the TCP / IP bus. The background monitoring and scheduling management layer is monitored and scheduled by the background monitoring and scheduling host.

[0068] Based on the above software design, the monitoring process of the wiring fault in the low-voltage CT automatic flow line test system with the added wiring fault monitoring device is as follows: information is collected by the information collection module 41 in the wiring fault device arranged at the withstand voltage table and the error table, the collected information is transmitted to the ARM control subsystem after being conditioned by the signal conditioning module, the input data is converted into displacement information by the data processing module after being converted from digital to analog in the ARM control subsystem, and the displacement range is determined according to the pre-set displacement range. If the displacement range exceeds the expected range, the monitoring and alarm module 426 is started to monitor and warn, and the video image acquisition module 427 is started to acquire the fault image of the corresponding measured mutual inductor station. The acquired video image information is transmitted to the video image monitoring host 43 through the image transmission module 428, and at the same time, the data information of the ARM control subsystem is transmitted to the video image monitoring host 43 through the RS485 bus. The video image monitoring host 43 transmits the monitoring result to the background monitoring and dispatching management layer.

[0069] Based on the above hardware and software design, the test process of the low-voltage CT automatic test system with the added wiring fault monitoring device is as shown in Figure 1 , which can be realized by the following steps:

[0070] (1) The AGV car auxiliary system realizes seamless docking with the out-of-warehouse conveying line of the mutual inductor warehouse through the interface, extracts and transports the measured mutual inductor turnover box stack, and sends the obtained turnover box information to the conveying unit. The low-voltage CT automatic test system adopts a distributed design, which is divided into a main system and an AGV auxiliary transmission subsystem. The two are arranged in parallel. The main system uses a roller and a belt conveying line to complete the transportation of the mutual inductor, and the subsystem uses the AGV car auxiliary transmission mode to complete the transportation from the docking platform to the test unit. The two transmission systems do not interfere with each other.

[0071] (2) The AGV car sends the measured mutual inductor turnover box stack to the unstacking / stacking station along the out-of-warehouse docking line, and the station manipulator unstacks one stack of three turnover boxes in order to the predetermined position, and puts the empty turnover box into the predetermined position.

[0072] (3) The loading station manipulator completes the loading, including fixture tray positioning, locking mechanism opening, automatic taking of the measured mutual inductor from the turnover box by the manipulator and placing it on the tray, and locking the locking mechanism after the measured mutual inductor is in place.

[0073] (4) The appearance detection conveying line sends the measured mutual inductor to the appearance detection station for appearance detection, including appearance front position image acquisition, top label image acquisition, appearance 90° left side position image acquisition, and appearance 90° right side position image acquisition.

[0074] (5) The insulation withstand transmission line sends the to-be-tested mutual inductor to the insulation withstand test station to perform to-be-tested mutual inductor tool tray station positioning, secondary wiring mechanism wiring, insulation resistance measurement, power frequency withstand voltage test, and after detection, the secondary wiring mechanism returns. Among them, the wiring state of the secondary wiring mechanism is monitored in real time by the mutual inductor secondary side wiring terminal wiring fault monitoring device, and if the wiring is successful, it sequentially enters the insulation resistance measurement process, and if the wiring is unsuccessful, the corresponding processing program of the wiring fault is started, and after fault processing, it reenters the subsequent insulation resistance measurement process.

[0075] (6) After the insulation withstand test, if it is qualified, it enters the error detection transmission line and is sent to the error calibration station; if it is unqualified, it enters the sorting net transmission line and is sent to the labeling line.

[0076] (7) In the error calibration station, first, the to-be-tested mutual inductor tool tray station positioning is performed, and then the secondary and primary wiring mechanism wiring is performed, and then the secondary winding turn-to-turn insulation strength test, magnetic saturation margin test, and basic error test are performed. Among them, the wiring state of the secondary wiring mechanism is monitored in real time by the mutual inductor secondary side wiring terminal wiring fault monitoring device, and if the wiring is successful, it sequentially enters the subsequent secondary winding turn-to-turn insulation strength test, etc., and if the wiring is unsuccessful, the corresponding processing program of the wiring fault is started, and after fault processing, it reenters the subsequent insulation resistance measurement process.

[0077] (8) The to-be-tested mutual inductor after error calibration is sent to the labeling station by the labeling station transmission line.

[0078] (9) The corresponding qualified / unqualified mutual inductor tool tray is positioned at the labeling machine, and a label is printed and labeled according to the test results of the previous process.

[0079] (10) After labeling, the return transmission line sends the calibrated mutual inductor to the unloading station. The unloading manipulator completes unloading, including tool tray positioning, locking mechanism opening, and automatic movement of the measured mutual inductor by the manipulator, and then the locking mechanism is locked. The unloading unit packs the mutual inductor and binds the mutual inductor barcode number, RFID, and box number, and stores the information in the calibration system database.

[0080] (11) The manipulator of the unstacking / stacking station moves the single turnover box filled with measured mutual inductors to the designated position, and stacks the subsequent turnover boxes into a group of three boxes.

[0081] (12) The AGV car sends the measured mutual inductor turnover box group to the warehouse entry transmission line along the warehouse entry connection line, realizing seamless connection between the automatic calibration system and the intelligent warehousing system.

[0082] In the above-mentioned low-voltage CT automatic verification system, in steps (5) and (7), the transformer secondary side terminal wiring fault monitoring device is additionally arranged in the secondary wiring mechanism of the withstand voltage table and the error table, and the mechanical structure of the monitoring device additionally arranged in the pipeline secondary wiring mechanism is shown in Figure 3 The secondary wiring mechanism mainly includes a tool tray 1, a transformer to be tested 2, a secondary wiring assembly 3, an additionally arranged transformer secondary side terminal wiring fault monitoring device 4, a profiled material 5, a cylinder sliding table 6, a guide rod sliding block 7, a magnetic induction switch 8, a drag chain 9, etc., and the design of the fault monitoring device is introduced in the following content.

[0083] As shown in (a) and (b) of Figure 4 , the secondary side terminal 21 of the transformer to be tested 2 includes, in sequence, a buried nut 211, a wiring bolt 212, a spring washer 213, a flat washer 214, and a primary conductor 215, the secondary side terminal 21 of the transformer to be tested 2 is made of copper and copper alloy with a resistivity of not more than , the body of the transformer to be tested 2 is made of thermosetting resin material, and the wiring bolt 212 matched with the secondary side terminal 21 of the transformer to be tested 2 is a cross-groove flat head bolt with a thread diameter of 6 mm, and the end face of the buried nut 211 matched with the wiring bolt 212 is 0.5-1.0 mm higher than the resin surface of the transformer body, the surface is smooth and clean, and meets the electrical contact requirements.

[0084] As shown in (a) and (b) of Figure 4 , the profiled material 5 of the pipeline secondary wiring mechanism is provided below the secondary wiring assembly 3, and the secondary wiring assembly 3 includes a measuring rod 31, a secondary wiring end 32, a screw 33, a pre-insulated terminal 34, a bolt 35, a test wire 36, a spring assembly 37, and a set screw 38. Figure 6 As shown in (a) and (b) of Figure 4As shown in (c), the hub device 10, the cylinder slide 6, the guide rod slide 7, the drag chain 9 and the like are assembled to the profile 5 at the corresponding positions through the corresponding connecting members. When the secondary wiring is performed, the secondary side wiring terminal 21 of the transformer is electrically connected with the pre-insulated wiring terminal 34 through the secondary wiring end 32 (which can also be referred to as the wiring end) of the assembly line test bench. The material of the measuring rod 31 is galvanized copper rod, and the lower part of the measuring rod 31 is processed with a cylindrical external thread. The lower part of the measuring rod 31 is assembled with the secondary wiring end 32 and the pre-insulated wiring terminal 34 through threaded connection. In order to keep fastening, the connection between the pre-insulated wiring terminal 34 and the secondary wiring end 32 is kept fastened by the bolt 35. Preferably, the secondary wiring end 32 is internally processed with an internal thread. After the lower part of the measuring rod 31 is assembled with the secondary wiring end 32 through threaded connection, the connection between the secondary wiring end 32 and the measuring rod 31 is further reinforced by the screw 33 assembled in the cylindrical threaded hole processed in the secondary wiring end 32.

[0085] The wiring state diagram of the secondary wiring mechanism of the assembly line test bench and the secondary side wiring terminal 21 of the transformer is shown in Figure 4 As shown in (d)-(g), the wiring process of the secondary wiring assembly 3 and the secondary side wiring terminal 21 of the transformer includes the following steps:

[0086] (1) First, after the workpiece tray 1 carrying the transformer to be tested 2 is positioned, the primary wiring mechanism is wired and the primary wire is pressed, the cylinder slide 6 drives the secondary wiring assembly 3 to descend to the predetermined position, and the secondary wiring end 32 of the secondary wiring assembly 3 (which can also be referred to as the secondary pressure contact assembly) is pressed to contact the secondary side wiring terminal 21 of the transformer to be tested 2. The height of the secondary side wiring terminal 21 is denoted as S.

[0087] The upper part of the measuring rod 31 in the secondary wiring assembly 3 is assembled with the spring assembly 37. In order to keep contact, the secondary wiring end 32 connected with the measuring rod 31 and the secondary side wiring terminal 21 of the transformer to be tested 2 are always kept in contact state through the elastic performance of the compression spring 371 in the spring assembly 37. Preferably, in order to keep the movement of the measuring rod 31 in the secondary wiring assembly 3, two cylindrical holes are provided in the body of the secondary wiring assembly 3, and the upper and lower bushings 312 and 311 are respectively assembled between the two cylindrical holes and the measuring rod 31 in the secondary wiring assembly 3. The lower bushing 311 and the upper bushing 312 are both assembled with the body of the secondary wiring assembly 3 through interference fit, and the lower bushing 311 and the upper bushing 312 are both assembled with the measuring rod 31 through clearance fit.

[0088] During the aforementioned crimping process, if the tooling tray 1 carrying the current transformer under test 2 is accurately positioned, the current transformer under test 2 on the tooling tray 1 does not tilt, or there is no air leakage in the air pipe of the cylinder slide 6, no fault in the solenoid valve, and no abnormality in the magnetic switch for positioning detection, then when the cylinder slide 6 drives the secondary wiring assembly 3 to descend to the specified height, the wiring terminal of the secondary wiring assembly 3 will definitely be able to accurately contact the secondary side wiring terminal 21 of the current transformer under test 2 as required. Figure 4 The pole drop state I shown in (d) Figure 4 The lowering state II is shown in (e); however, if the above-mentioned abnormal situation occurs, during the descent of the cylinder slide 6 driving the secondary wiring assembly 3, there is a possibility that it will stop at a height other than the specified height, such as... Figure 4 The pole drop state III is shown in (f). Figure 4 Abnormal conditions such as the drop state IV shown in (g) may cause the wiring terminals of the secondary wiring assembly 3 to fail to make contact with the secondary side wiring terminals 21 of the transformer under test 2 as expected.

[0089] Analyzing the various wiring scenarios described above, during actual operation of the production line, it may occur that although the terminal positions of the secondary wiring assembly 3 are abnormal, they still maintain partial contact with the front side terminals of the current transformer (e.g., Figure 4 As shown in (e), the situation of side contact indicates that the wiring terminal can still maintain electrical contact, and therefore does not constitute a wiring fault. However, for... Figure 4 Abnormal situations such as (f) and (g) Figure 4 The downward displacement of the wiring terminal of the secondary wiring assembly 3 shown in (f) and (g) exceeds the displacement range s corresponding to normal contact. The technical specification for low-voltage CT for metrology, Q / GDW10572.1-2020, stipulates that the external dimensions and mating dimensions of the CT must meet the m-level accuracy requirements of GB / T1804, the height inconsistency between the secondary terminals S1 and S2 of the CT under normal bolt tightening conditions must not exceed 2mm, and the vertical dimensional tolerance of the CT must not exceed 3mm. However, the error at the pallet station in the automated CT verification line typically reaches the millimeter level. Therefore… Figure 4 Abnormalities such as (f) and (g) indicate wiring faults.

[0090] Furthermore, based on the above analysis of the abnormal position patterns of the wiring terminals of the secondary wiring assembly 3, it can be concluded that by measuring the downward displacement s of the wiring terminals of the secondary wiring assembly 3, the success or failure of the connection between the secondary wiring assembly 3 and the secondary side wiring terminals of the transformer under test can be indirectly detected. Based on this fault monitoring and testing mechanism analysis, this embodiment proposes a fault monitoring device for the wiring terminals of the secondary side of the transformer in the automated verification of low-voltage CTs based on a differential transformer displacement sensor. Figure 5As shown, the device is used to measure the downward displacement of the terminal of the secondary wiring assembly 3, to preliminarily determine the wiring state of the secondary terminal, and once the displacement s exceeds the specified range, it is preliminarily determined that there is a wiring fault, at which time the video monitoring device is started to collect the video image of the corresponding station, the information is uploaded to the video image monitoring host through the image transmission module, the fault mode and fault state of the wiring fault are identified by calling the image recognition model in the database, and after the secondary determination determines that the wiring fault, the monitoring and early warning are started, thereby realizing the real-time and rapid monitoring of the secondary terminal wiring fault in the low-voltage CT automatic detection. Correspondingly, if the system determines that the wiring fault occurs, the video image monitoring host will synchronously transmit the monitoring result to the HMI detection monitoring control host and the unit control execution layer, and the detection system automatically controls the switching to manual control, and the on-site staff executes fault elimination, and after the fault is handled, it is switched back to the system to enter the subsequent operation.

[0091] (2) If the secondary wiring is successful, the corresponding PLC system control starts the detection test of the corresponding item.

[0092] (3) After the test is completed, the primary and secondary wiring is loosened, the cylinder sliding table 6 drives the secondary wiring assembly 3 to rise, the track of the secondary wiring assembly 3 descending or rising is guaranteed to run through the guide rod sliding block 7 mechanism, the drag chain 9 drives the secondary wiring assembly 3 to descend or rise to the specified height, and the specific height position of the descending or rising is controlled through the magnetic induction switch 8 in the cylinder sliding table 6.

[0093] (4) Finally, the primary guiding and wiring mechanism moves out of the conveying line, the through-hole mechanism is withdrawn, and the measured sensor is transmitted out of the station.

[0094] Based on the above principle analysis, the low-voltage CT wiring fault monitoring device 4 proposed in the embodiment is arranged outside the secondary wiring assembly 3 in the secondary wiring mechanism of the assembly line, and includes an information acquisition module 41, a signal measurement and control terminal 42, and a video image monitoring host 43. The device will be introduced in more detail through the following contents.

[0095] (1) For the information acquisition module

[0096] The information acquisition module 41 includes a linear displacement measurement sensor 411 and a sensor clamping mechanism 412, wherein the linear displacement measurement sensor 411 adopts a differential transformer type displacement sensor, which is used to acquire the displacement information of the terminal of the measuring rod in the secondary wiring assembly, and the sensor clamping mechanism 412 is a mechanical structure device adapted to the structure type of the sensor. The mechanism is assembled on the secondary wiring assembly 3 and is used to fix the linear displacement measurement sensor 411.

[0097] (2) For the signal measurement and control terminal

[0098] As shown in FIG. 4, the signal measurement and control terminal 42 includes a signal acquisition module 421, a signal processing module 422, and a signal transmission module 423. The signal acquisition module 421 is used to acquire the displacement information of the terminal of the measuring rod in the secondary wiring assembly, and the signal processing module 422 is used to process the displacement information of the terminal of the measuring rod in the secondary wiring assembly. The signal transmission module 423 is used to transmit the processed displacement information of the terminal of the measuring rod in the secondary wiring assembly to the video image monitoring host 43. Figure 5As shown, the signal measurement and control terminal 42 includes an excitation signal generation module 421, a signal conditioning module 422, a drive amplification module 423, an analog-to-digital conversion module 424, an ARM control subsystem 425, a monitoring alarm module 426, a video image acquisition module 427, a video transmission module 428, an RS485 level conversion module 429, and a voltage conversion module 430, etc.

[0099] Through the differential transformer type displacement sensor in the above information acquisition module, the displacement carrier information is adopted, and for the collected information, the signal demodulation mode of analog and digital combination is adopted, and the miniaturized and integrated chip AD698 is used to realize signal excitation and conditioning. Specifically, the excitation signal generation module 421 is used to generate the sine wave excitation signal required to drive the linear displacement measurement sensor 411; the signal conditioning module 422 is used to receive the displacement signal collected by the sensor and demodulate and amplify the sensor output signal; in the drive amplification module 423, AD8065 in-phase proportional amplification circuit and AD8065 voltage follower are arranged, which are respectively used to perform signal amplification and voltage offset conditioning; the analog-to-digital conversion module 424 adopts high-precision low-power device AD7988-1, AD7988-1 is used as a 16-bit fast, low-power, precise, successive approximation type analog-to-digital converter, which adopts 2.5V single power supply, and the data conversion rate can reach 100Ksps throughput. The chip provides sample and hold inside without any pipeline delay. The analog-to-digital conversion module 424 is used to convert the processed analog signal into digital signal for subsequent signal processing; the ARM control subsystem 425 adopts low-power ARM core single-chip microcomputer STM32L476 as the main controller, which is used to convert the received digital signal into displacement information, compares the displacement information with the preset displacement range, judges whether there is a wiring fault, generates and issues a wiring fault control instruction, wherein when it is judged that there is a wiring fault, the control instruction is generated and issued to the monitoring alarm module 426, the video image acquisition module 427, the video transmission module 428, etc., otherwise no operation; the monitoring alarm module 426 is used for wiring fault alarm; the video image acquisition module 427 adopts industrial cameras, such as industrial cameras based on Hikvision MV-CA020-10GC, OV7670 CMOS image sensor, etc. The gigabit Ethernet interface of the industrial camera can conveniently perform information transmission to the video image monitoring host 43. This module is used to start the camera to collect the corresponding station fault image information according to the wiring fault control instruction; the video transmission module 428 is composed of SCCB bus, STM32 control subsystem and Zigbee transmission line-free module based on CC2530 to realize communication transmission and data interaction between parts, and is used to transmit the collected image information to the video image monitoring host 43.

[0100] (3) For the video image monitoring host

[0101] In the video image monitoring host 43, for the digital image transmitted by the signal measurement and control terminal 42, the YOLO v8-based image recognition model 431 stored in the database is called to identify the fault mode and fault state of the wiring fault in the image, so as to perform secondary identification and confirmation of the wiring fault, and complete the automatic identification and positioning of the wiring fault mode. At the same time, when the wiring fault is determined, the identification result is synchronized to the HMI detection monitoring control host and the unit control execution layer, providing data support for subsequent reliable analysis and management, and real-time control of the test system switching to manual control. After troubleshooting, re-enter the subsequent operation.

[0102] Preferably, the video image monitoring host 43 communicates with the signal measurement and control terminal 42 through the RS485 bus for transmission and data interaction. When the video image monitoring host 43 identifies the fault mode and fault state of the wiring fault, the identification information is transmitted to the signal measurement and control terminal 42, converted by the RS485 level conversion module 429, and then transmitted to the ARM control subsystem 425. The ARM control subsystem 425 controls the monitoring alarm module 426 to alarm the wiring fault according to the received identification signal.

[0103] Through the above fusion of displacement monitoring and image monitoring, first-time monitoring and early warning can be provided when the wiring fault occurs, so that the fault can be handled in a timely manner. In addition, the video image is collected synchronously when the fault occurs, which can avoid the storage pressure of the monitoring equipment caused by continuous image collection of the work station, realize condition-based collection and no condition-based collection, thereby reducing the cost of the assembly line operation and maintenance, and providing necessary data information for subsequent reliability analysis and management.

[0104] Further, to realize indirect automatic collection of the position information of the wiring end of the secondary wiring assembly, the embodiment proposes a design of a sensor and its clamping mechanism suitable for the architecture conditions of the assembly line project detection station. This design mainly considers three factors: (1) It needs to be compatible with the existing structure of the assembly line, that is, the linear displacement measurement sensor 411 needs to be clamped in the limited space of the movable measuring rod 31 in the secondary wiring assembly 3; (2) It needs to ensure that the measuring rod 31 and the spring assembly 37 assembled on the top thereof remain in contact; (3) It needs to consider the actual situation of the frequent up-and-down movement of the measuring rod 31 in the wiring assembly during the continuous operation of the assembly line.

[0105] As an embodiment, as shown in Figure 6 the information collection module 41 adopts a three-section differential transformer type displacement sensor and its clamping method. In the embodiment, as shown in Figure 6As shown in (a), the linear displacement measurement sensor 411 mainly consists of a signal wire slot hole 4111, one primary coil 4112, two secondary coils 4113, a coil backbone 4114, an iron core 4115, an iron core connecting rod 4116, an insulation layer 4117, and four test cables 4118 (signal wires), wherein the linear displacement measurement sensor 411 performs detection of the position of the terminal head in the secondary wiring assembly 3 based on the linear variable differential transformer mode.

[0106] Specifically, as shown in (a), Figure 6 As shown in (b), the skeleton shape of the coil backbone 4114 is a three-section I-shaped cylinder, the skeleton material of the coil backbone 4114 is selected from beryllium bronze with a small temperature expansion coefficient and good magnetic circuit symmetry effect, and the skeleton of the coil backbone 4114 is internally provided with a hollow cylindrical space, a movable cylindrical rod-shaped iron core 4115 is arranged at the middle position of the space, the iron core 4115 is fixedly connected with the iron core connecting rod 4116 below it by welding, and the iron core connecting rod 4116 is fixedly connected with the upper end of the measuring rod 31 of the secondary wiring assembly 3 through the sleeve coupling 4121, so that the position movement of the measuring rod 31 and the terminal head connected thereto can be reflected and obtained through the movement of the sensor iron core 4115, thereby forming an iron core movable transformer type linear displacement measurement sensor 411. Preferably, the iron core is made of strong magnetic material 4140 alloy steel with high magnetic permeability, high strength, good toughness, and large saturation magnetic induction, and the iron core connecting rod 4116 fixedly connected with the iron core 4115 is made of non-magnetic stainless steel.

[0107] Further, the primary coil 4112 and the two secondary coils 4113 are wound on the skeleton of the coil backbone 4114, the primary coil 4112 is wound on the middle section of the skeleton of the coil backbone 4114, and the two secondary coils 4113 are symmetrically wound on the upper section and the lower section of the skeleton of the coil backbone 4114 in the same winding manner, and are arranged in a reverse series connection form to constitute a differential phase connection mode, the voltage polarity of the two secondary coils 4113 is opposite, and in addition, the coil material is enameled copper wire, and the coil periphery after winding is coated with an insulation film as an insulation layer 4117 for insulation treatment.

[0108] Based on the above design, as shown in (c), Figure 6 When the iron core 4115 is at the middle position, the induced electromotive forces generated by the two secondary coils 4113 are equal in size and opposite in direction, at this time the output voltage is zero, which is called "zero position"; when the iron core 4115 moves in the coil and deviates from the center position, the induced electromotive forces generated by the two coils are not equal, then there is voltage output. As shown in (c), Figure 6 As shown in (c), P represents the iron core, and the inductance formed by the primary coil 4112 is , which is connected with an external excitation alternating voltage, PFrom the above point Moving to , the inductance formed by the 2 secondary coils 4113 is and The voltage formed by the 2 secondary coils 4113 is and The voltage difference is Further, when the primary coil 4112 of the sensor is connected to an excitation alternating voltage signal, a voltage is generated in the secondary coil 4113 through mutual inductance in the electromagnetic induction effect, and the size of the voltage generated in the secondary coil 4113 is linearly related to the position of the iron core 4115. The output is the voltage difference of the two secondary coils 4113, and the corresponding displacement information can be obtained after processing based on the voltage difference. In actual engineering application, due to manufacturing errors, the parameters of the two secondary coils 4113 cannot be completely consistent, so the output is not necessarily zero when the iron core 4115 is at zero position. A zero residual voltage compensation circuit can be set up to reduce the influence of the zero point residual voltage of the sensor.

[0109] The sensor clamping mechanism 412 mainly includes a sleeve coupling 4121, an adjusting washer 4122, a guide sleeve 4123, a support shaft sleeve 4124, a mounting top cover 4125, two mounting bolts 4126, a sensor protection shell 4127, a wiring assembly body 4128, a wire bundler 4129, etc. In the sensor clamping mechanism 412, an adjusting washer 372 is installed between the top end of the guide sleeve 4123 and the wiring assembly body 4128, and two installation positioning teeth are arranged at the bottom end of the guide sleeve 4123. After assembly, the two positioning teeth holes opened in the upper end surface of the coil backbone 4114 of the sensor can prevent the sensor from rotating circumferentially. After the sensor and the guide sleeve 4123 are clamped by the positioning teeth, the support shaft sleeve 4124 and the mounting top cover 4125 are assembled and fixed, and the mounting top cover 4125 is fixed on the wiring assembly body 4128 by the two mounting bolts 4126. Further, in order to ensure good linearity of the sensor output signal and strong anti-interference ability, the sensor protection shell 4127 is made of a weak magnetic material such as non-magnetic stainless steel; the support shaft sleeve 4124 is provided with a signal wiring slot hole 4111 for leading out the sensor test signal line. The sensor test signal line has 4 leads, which are wound into a test cable 4118 and attached to the spring pressing part 373 through the wire bundler 4129, so as to ensure the transmission of the sensor electrical signal.

[0110] In addition, the test cable 4118 of the secondary side terminal connection fault monitoring device 4 of the low-voltage CT automatic verification pipeline is introduced into the signal conditioning module 422 input end in the groove of the profile 5 through the concentrator 10. The excitation signal generation module 421, the signal conditioning module 422, the drive amplification module 423, the analog-to-digital conversion module 424, the ARM control subsystem 425, and the like circuit boards in the signal measurement and control terminal 42 are all installed in the terminal test box and placed in the corresponding groove of the profile 5. The monitoring and alarm module 426, the video image acquisition module 427, and the image transmission module 428 are arranged on the side column of the pipeline to-be-measured mutual inductor station.

[0111] In the above manner, by selecting the differential transformer type displacement sensor and the corresponding mechanical sensor clamping mechanism, the signal acquisition design with lower cost can be realized, and the high stability and high reliability of the wiring assembly during frequent use can be ensured.

[0112] As another embodiment, to further realize the test requirement of high-precision displacement detection, the linear displacement measurement sensor 411 and the sensor clamping mechanism 412 of the information acquisition module 41 are improved and designed, so that the linear displacement measurement sensor 411 can accurately test the position information of the terminal end in the wiring assembly based on the linear variable differential transformer method.

[0113] As shown in Figure 7 , the sensor clamping mechanism 412 mainly consists of a sleeve 41212, a sleeve upper end cover 41211, an upper shaft sleeve 41213, a lower shaft sleeve 41214, a fastening screw 41216, and a small compression spring 41215. In the sensor clamping mechanism 412, the sleeve 41212 and the sleeve upper end cover 41211 are nested and clamped, which can be disassembled; the compression spring 371 is installed on the sleeve upper end cover 41211, and the adjustment pad 372 is arranged between the compression spring 371 and the body of the secondary wiring assembly 3; the sleeve 41212 is designed as a cylindrical upper end and two comb teeth at the lower end, which are arranged in a 180-degree direction and cross the two clamping bases of the lower shaft sleeve 41214 to be assembled in a 180-degree staggered manner, as shown in the partial cross-sectional view A-A. Figure 7 As shown in the partial cross-sectional view A-A, the two comb teeth at the bottom of the sleeve 41212 are directly assembled with the spring pressing part 373.

[0114] The linear displacement measurement sensor 411 adopts the LT20 displacement sensor. The sensing coil and the signal conditioning assembly of the differential transformer type displacement sensor are all assembled in the cylindrical stainless steel shell of the LT20 displacement sensor, as shown in the sensor. Figure 7 The sensor iron core 4115 is placed in the cylindrical hole at the bottom of the sensor stainless steel shell and moves up and down. The sensor iron core 4115 is assembled and connected with the upper end of the measuring rod 31 of the secondary wiring assembly 3 through a threaded connection method, as shown in Figure 7As shown in (a) and (b), the upper end of the measuring rod 31 is machined into a screw-like structure, replacing the original measuring cap of the LT20 sensor during assembly. During the operation of the secondary wiring assembly 3, the displacement of the measuring rod 31 and its connected terminals is reflected in the DC voltage output information of the sensor through the movement of the sensor core 4115. To maintain the sensor body's position fixed during the movement of the sensor core 4115, the sensor's stainless steel housing is fixedly engaged with the upper bushing 41213 and the lower bushing 41214 via an interference fit. The lower end of the lower bushing 41214 has two mounting bases at 180 degrees to each other, each with corresponding threaded holes. Two fastening screws 41216 are used to clamp the lower bushing 41214 onto the body of the secondary wiring assembly 3, thereby fixing the sensor's stainless steel housing, which is fixed to the lower bushing 41214, onto the body of the secondary wiring assembly 3. The upper bushing 41213, lower bushing 41214, and the cylindrical inner wall of the sleeve 41212 are assembled with a clearance fit, thereby ensuring that when the measuring rod 31 moves up and down, the sensor core 4115 can reciprocate linearly within the sensor. Figure 7 As shown in (c), the two clamping bases at the lower end of the lower bushing 41214, which are 180 degrees apart, and the two comb teeth at the lower end of the sleeve 41212 are assembled in an alternating manner to form two sets of fork-comb assembly. This structural design can ensure that the sensor core 4115 moves linearly within the sensor fixed to the secondary wiring assembly 3, and also ensure that as the measuring rod 31 moves up and down, the movement of the measuring rod can maintain elastic contact with the compression spring 371 of the spring assembly 37 through the connection between the sleeve 41212 and its upper end cap. This ensures elastic compression electrical contact between the wiring terminals of the secondary wiring assembly 3 and the secondary side wiring terminals of the current transformer. A small compression spring 41215 is clamped between the spring clamping member 373 of the spring assembly 37 and the lower end face of the stainless steel housing of the sensor to ensure the buffered movement of the core 4115 and prevent overshoot. The sensor's signal test line 36 is led out through the gap between the upper bushing 41213, the lower bushing 41214 and the sleeve 41212, and through the signal routing slot 4111 of the lower bushing 41214.

[0115] In addition, the excitation signal generation module 421, signal conditioning module 422, drive amplification module 423, etc. in the signal measurement and control terminal 42 are directly integrated into the sensor. The DC voltage signal output by the LT20 displacement sensor is input to the main control equipment after analog-to-digital conversion through the input analog-to-digital conversion module 424.

[0116] The above methods enable more accurate displacement monitoring. Both mechanical structure schemes of the sensor and its clamping mechanism have the advantages of input-output isolation, frictionless measurement, unlimited mechanical life, unlimited resolution, and durability, making them suitable for low-pressure CT automated verification production line scenarios.

[0117] Example 2

[0118] This embodiment provides a method for monitoring low-voltage CT wiring faults in automated low-voltage CT calibration. Utilizing the low-voltage CT wiring fault monitoring device proposed in Embodiment 1, it performs real-time monitoring of the secondary wiring process during the automated low-voltage CT production line calibration, including:

[0119] Step S1: The secondary wiring assembly moves downward, and its wiring terminals come into contact with the secondary side wiring terminals of the low-voltage CT under test, and the displacement information of the wiring terminals is collected in real time.

[0120] Specifically, after the low-voltage current transformer under test completes its positioning and other processes at the tray station, the secondary wiring mechanism initiates wiring. During this process, a wiring fault monitoring device monitors for wiring faults in real time. When the secondary wiring assembly 3 descends to the designated position, the secondary wiring terminal 32 of the secondary wiring assembly 3 contacts the secondary side wiring terminal 21 of the transformer. The tightness of this contact is ensured by the elasticity of the spring assembly 37 mounted on the top of the measuring rod 31. It should be noted that the S1 and S2 operation methods for the secondary side wiring terminal 21 of the transformer are the same; only one method will be used in the subsequent description.

[0121] The contact between the secondary wiring terminal 32 and the secondary side wiring terminal 21 of the current transformer actually refers to the electrical contact between the secondary wiring terminal 32 of the secondary wiring assembly 3 and the exposed part of the embedded nut 211 or wiring bolt 212 of the secondary side wiring terminal 21 of the current transformer. If the secondary wiring terminal 32 contacts the transformer body outside the exposed part of the embedded nut 211 or wiring bolt 212 of the secondary side wiring terminal 21 of the current transformer due to errors in the shape or position of the current transformer under test, the contact will fail because the transformer body is made of thermosetting resin material. When a wiring fault occurs due to contact failure, the position of the measuring rod 31 in the secondary wiring assembly 3 is higher or lower than its standard position within the specified range, such as... Figure 4 The pole drop state III shown in (f) Figure 4 The positional change of the pole in state IV shown in (g) can be reflected by the displacement information collected by the sensor's information acquisition module 41.

[0122] Step S2: After signal conditioning and analog-to-digital conversion of the collected displacement information, it is transmitted to the ARM main control system. The ARM main control system compares the displacement information with the preset displacement range to determine whether there is a wiring fault.

[0123] Specifically, the test of the terminal position information is realized by the information acquisition module 41, and the position data information of the 12 stations is processed by the signal measurement and control terminal 42 to complete signal conditioning, and then converted into digital signals by an analog-to-digital converter and entered into the ARM control subsystem 425. The ARM control subsystem 425 determines the wiring fault according to the collected displacement information, and if it is determined that the terminal position exceeds the standard, it is preliminarily determined that there is a wiring fault.

[0124] Step S3, when it is determined that there is a wiring fault, starting the fault early warning and synchronously starting the collection of the wiring fault image.

[0125] Specifically, when the ARM control subsystem 425 determines that there is a wiring fault, the monitoring alarm module 426 is started to give an audible and visual early warning, and the video image acquisition module 427 is started to collect the video image of the corresponding station.

[0126] Step S4, according to the collected wiring fault image, using an image recognition model to recognize the fault mode and state, and synchronously transmitting the recognition result to the HMI detection monitoring control host and the unit control execution layer in the assembly line.

[0127] Specifically, the video image information collected by the video image acquisition module 427 is transmitted to the video image monitoring host 43 system by the video transmission module 428, the image recognition model 431 in the database is called, the target detection algorithm based on YOLOv11 deep learning is used to recognize the mode and state of the wiring fault in the image, and the automatic intelligent recognition of the wiring fault is completed. On this basis, the video image monitoring host 43 synchronously transmits the result to the HMI detection monitoring control host and the unit control execution layer, the detection system is switched to manual control, and after the fault is eliminated, it reenters the subsequent operation.

[0128] The steps involved in the above embodiment two correspond to those of embodiment one, and the specific implementation can refer to the related description part of embodiment one.

[0129] The above only describes the preferred embodiments of the present application, and the specific implementation of the present application is described with reference to the accompanying drawings, but it is not a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications or changes made by those skilled in the art on the basis of the technical solutions of the present application without creative labor are still within the protection scope of the present application.

Claims

1. A low-voltage CT wiring fault monitoring device for automated low-voltage CT calibration, characterized in that, The secondary wiring assembly, installed on the secondary wiring mechanism in the low-pressure CT automated verification line, includes: The information acquisition module includes a differential transformer-type linear displacement measurement sensor, which is used to acquire the displacement electrical signal of the end terminal of the measuring rod in the secondary wiring assembly in real time; The signal measurement and control terminal is used to process the collected displacement electrical signals, generate displacement information, compare the displacement information with the preset displacement range, determine whether there is a wiring fault, and issue a wiring fault warning and collect the corresponding workstation wiring fault image based on the judgment result. The video image monitoring host is used to identify the pattern and status of the wiring fault in the acquired wiring fault images using a pre-stored image recognition model, and synchronize the recognition results to the control host of the production line. The information acquisition module also includes a sensor clamping mechanism, which is mounted on the secondary wiring assembly and used to fix the linear displacement measurement sensor. The information acquisition module adopts a three-segment differential transformer linear displacement measurement sensor and a sensor clamping mechanism that matches the sensor. The linear displacement measuring sensor includes a primary coil, two secondary coils, a coil frame, an iron core, a connecting rod, and a test cable. The coil frame is shaped like a three-section I-beam cylinder. The primary coil and the two secondary coils are wound around the coil frame, with the two secondary coils symmetrically distributed on both sides of the primary coil and connected in reverse series to form a differential connection. The coil frame has a hollow cylindrical space inside, with a movable cylindrical rod-shaped iron core located in the middle. The iron core is fixedly connected to the connecting rod below it by welding. The other end of the connecting rod is fixedly connected to the upper end of the measuring rod in the secondary wiring assembly via a sleeve coupling, forming a movable iron core transformer-type linear displacement measuring sensor. The test cable connects to the primary coil and the two secondary coils for signal transmission. The sensor clamping mechanism includes a sleeve coupling, adjusting washers, guide sleeves, support bushings, a mounting top cover, mounting bolts, a sensor protective housing, and a cable tie. An adjusting washer is installed between the top of the guide sleeve and the secondary wiring assembly body. The bottom of the guide sleeve has mounting positioning teeth that mate with positioning tooth holes on the upper surface of the coil keel to prevent circumferential rotation of the sensor. The sensor is assembled with the mounting top cover via the support bushing, and the mounting top cover is fixed to the secondary wiring assembly body by mounting bolts. A sensor protective housing is fitted over the sensor, and the cable tie is used to secure the test cable. The information acquisition module uses an LT20 linear displacement measurement sensor and a sensor clamping mechanism that matches the sensor. The induction coil and signal conditioning components of the LT20 linear displacement measuring sensor are assembled in a stainless steel metal shell, and the iron core is placed in a cylindrical hole at the bottom of the shell and is connected to the upper end of the measuring rod of the secondary wiring assembly by a thread. The sensor clamping mechanism includes a sleeve, an upper sleeve cap, an upper bushing, a lower bushing, fastening screws, and a small compression spring. The sleeve and upper sleeve cap are nested and detachably clamped together. The upper sleeve cap is fitted with a compression spring, and an adjusting shim is provided between the compression spring and the secondary wiring assembly body. The sleeve is cylindrical at the top and has two comb-like teeth at the bottom. The two comb-like teeth at the bottom of the sleeve are arranged at 180 degrees and are cross-assembled with the two clamping bases of the lower bushing. The lower bushing is fixed to the secondary wiring assembly body by fastening screws. The small compression spring is clamped between the spring clamping element of the secondary wiring mechanism and the stainless steel housing of the sensor. The stainless steel metal shell of the LT20 linear displacement measuring sensor is fixedly connected to the upper and lower bushings by interference fit. The upper and lower bushings are clearance-fitted with the cylindrical inner wall of the sleeve. The signal test wires in the secondary wiring assembly are led out through the gap between the upper and lower bushings and the sleeve, and through the wiring slot of the lower bushing.

2. The low-voltage CT wiring fault monitoring device in the automated verification of low-voltage CT as described in claim 1, characterized in that, For the insulation withstand voltage test station and error verification station of the low-voltage CT automated verification line, a low-voltage CT wiring fault monitoring device is installed on the secondary wiring component in the secondary wiring mechanism of the station. During the insulation resistance measurement, power frequency withstand voltage test, secondary winding inter-turn insulation strength test, magnetic saturation margin measurement, and basic error measurement processes on the production line, a low-voltage CT wiring fault monitoring device is used to monitor the wiring faults of the secondary side terminals of the low-voltage current transformer in real time.

3. The low-voltage CT wiring fault monitoring device in the automated low-voltage CT calibration as described in claim 1, characterized in that, The iron core is made of a strong magnetic material with high permeability, high strength, and high magnetic induction intensity; the iron core connecting rod is made of non-magnetic stainless steel; and the sensor protective shell is made of a weak magnetic material.

4. The low-voltage CT wiring fault monitoring device in the automated calibration of low-voltage CT as described in claim 1, characterized in that, The signal measurement and control terminal includes: The excitation signal generation module is used to generate the sinusoidal excitation signal required to drive the linear displacement measurement sensor; The signal conditioning module is used to receive the displacement electrical signal collected by the sensor and to demodulate and amplify the signal. The driver amplifier module is equipped with an AD8065 non-inverting amplifier circuit and an AD8065 voltage follower, which are used to amplify the signal and condition the voltage offset, respectively. The analog-to-digital converter module is used to convert the processed analog signal into a digital signal; The ARM control subsystem is used to convert the received digital signals into displacement information, compare the displacement information with the preset displacement range to determine whether there is a wiring fault, and generate and issue wiring fault control commands. The monitoring and alarm module is used to issue alarms for wiring faults; The video image acquisition module is used to start the camera to acquire images of the corresponding workstation wiring fault according to the wiring fault control command; The image transmission module is used to transmit the acquired images to the video image monitoring host.

5. A method for monitoring low-voltage CT wiring faults in automated low-voltage CT calibration, characterized in that, Using the low-voltage CT wiring fault monitoring device as described in any one of claims 1-4, real-time monitoring of the secondary wiring process during the calibration of a low-voltage CT automated production line is performed, including: The secondary wiring assembly moves downwards, and the wiring terminals in the assembly contact the secondary side wiring terminals of the low-voltage CT under test, and the displacement electrical signal of the wiring terminals is collected in real time. After signal conditioning and analog-to-digital conversion of the collected displacement electrical signal, displacement information is obtained. Based on the comparison between the displacement information and the preset displacement range, it is determined whether there is a wiring fault. When a wiring fault is detected, a fault warning is activated and the acquisition of wiring fault images is initiated simultaneously. Based on the collected wiring fault images, the fault mode and status are identified using an image recognition model, and the identification results are synchronized to the HMI detection and monitoring control host and unit control execution layer in the production line.

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