A system for testing the insulation resistance of an electrolyzer end press plate assembly and a method of testing the same

Abstract

This invention discloses an insulation resistance testing system and method for an electrolytic cell end plate assembly, comprising: an end plate body, end plates, multiple tie rod bolts, and a grounding bracket; test terminals, including low-voltage test terminals and multiple high-voltage test terminals, wherein the low-voltage test terminals are fixedly mounted on the end plate body and electrically connected to the metal portion of the end plate body; the multiple high-voltage test terminals are respectively disposed on the end plates, each tie rod bolt, and the grounding bracket, each high-voltage test terminal being electrically connected to the corresponding component's metal portion and insulated from the end plate body and other components; a centralized junction box, wherein the leads of the low-voltage test terminals and each high-voltage test terminal are connected and converged inside the centralized junction box; and an insulation resistance tester connected to the high-voltage and low-voltage test terminals, having two modes: fixed voltage testing and stepped voltage diagnostic testing. This invention provides convenient testing and can accurately locate faulty components.

Description

Technical Field

[0001] This invention relates to the field of electrolysis technology, and specifically to an insulation resistance testing system and method for an electrolytic cell end pressure plate assembly. Background Technology

[0002] During the manufacturing, installation, and operation and maintenance of alkaline electrolytic cells, the insulation performance of key structural components such as end plates, end electrodes, tie rod bolts, and grounding supports must be rigorously tested to prevent safety accidents such as leakage, short circuits, and electric shocks. The insulation performance of the electrolytic cell end plate assembly directly affects the safe operation of the equipment and personal safety. The end plate assembly includes components such as end plates, end electrodes, tie rod bolts, and grounding supports. The end plates are usually connected to the plant grounding system, while the end electrodes are live components. The tie rod bolts and grounding supports must maintain good insulation from the end plates.

[0003] Current insulation resistance testing techniques typically employ the following method: connecting the high-voltage terminal of the insulation tester to the component under test, and the low-voltage terminal to the equipment casing or grounding system. However, this existing technology has the following shortcomings: 1. Scattered test points: Each test requires temporarily locating test points, grinding the surface, and clamping the test leads, which is cumbersome and has poor repeatability. Furthermore, the messy test leads increase the risk of accidental short circuits and compromise safety.

[0004] 2. Low efficiency of multi-point testing: Testing multiple components requires repeated disconnection and reconnection of high-voltage wires, which is cumbersome, inefficient, and poses safety hazards. Some testing schemes also require disassembling components, which can easily damage the electrolytic cell structure, affecting its sealing performance and structural strength.

[0005] 3. Inability to pinpoint potential faults: When the overall insulation resistance decreases, it is difficult to quickly locate which component's insulation has a problem. It is also difficult to detect potential issues such as weak insulation, moisture absorption, or localized aging. 4. Inconsistent test potentials: Different testers select different test points, resulting in poor comparability of test data and making it impossible to establish an effective historical trend curve.

[0006] Therefore, the industry urgently needs an insulation testing solution that features centralized wiring, safe operation, no disassembly required, fault location capabilities, and accurate assessment of insulation status. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an insulation resistance testing system and method for electrolytic cell end plate assemblies. The aim is to achieve fixed testing points and greatly simplify operation by setting the unenergized end plate as a low-voltage common terminal and other components as high-voltage test points, thereby solving the problems of inconvenient testing, low efficiency, and inability to locate faults in existing technologies. The specific technical solution is as follows: An insulation resistance testing system for an electrolytic cell end plate assembly includes: An electrolytic cell end plate assembly includes: an end plate body; an end electrode plate disposed inside the end plate body and having an insulating layer between it and the end plate body; a plurality of tie rod bolts penetrating the end plate body for pressing the entire electrolytic cell stack; and a grounding bracket insulated from the end plate body for connecting to a grounding system. The test terminals include low-voltage test terminals disposed on the end plate body and electrically connected to the metal part of the end plate body; and multiple high-voltage test terminals, including a first high-voltage test terminal, a second high-voltage test terminal, and a third high-voltage test terminal; wherein, the first high-voltage test terminal is provided on the end plate, the second high-voltage test terminal is provided on the grounding bracket, and each tie rod bolt is provided with an independent third high-voltage test terminal; each high-voltage test terminal is electrically connected to the metal part of the corresponding component, and the end plate body is insulated from its components; A centralized junction box, in which all the low-voltage test terminals and each high-voltage test terminal are connected by leads; An insulation resistance tester has a high-voltage output terminal and a low-voltage input terminal. The high-voltage output terminal can be selectively connected to any high-voltage test terminal, and the low-voltage input terminal is connected to the low-voltage test terminal. The insulation resistance tester includes two test modes: voltage test and step voltage diagnostic test.

[0008] Preferably, the low-voltage test terminal is arranged on the side or top of the end plate body, adopts a recessed structure, its contacts are recessed into the surface of the end plate, and a self-closing dust cover is arranged at the opening.

[0009] Preferably, the first high-voltage test terminal on the end plate is fixed to the tab of the end plate and connected to the end plate through a high-voltage isolation resistor. The high-voltage isolation resistor has a resistance of 1-10MΩ and is used to isolate high voltage during normal operation of the electrolytic cell, limiting the voltage / current of the test terminal to a safe range.

[0010] Preferably, the third high-voltage test terminal on the tie rod bolt is a test ring fitted onto the bolt head. Each test ring is connected to a central junction box via an independent lead wire. The test ring is in metal contact with the bolt head but is insulated from the end pressure plate.

[0011] Preferably, the centralized junction box is a waterproof, dustproof, and shockproof structure, and contains: a low-voltage common terminal block for connecting to the low-voltage test terminal of the end plate body; multiple high-voltage selection terminals for connecting to each high-voltage test terminal; a multi-way selector switch for switching between the multiple high-voltage selection terminals to connect the selected high-voltage test terminal to the high-voltage output terminal of the insulation resistance tester; a busbar for short-circuiting all high-voltage test terminals for overall testing; a desiccant chamber containing color-changing silica gel desiccant; and a waterproof sealing connector for lead wire entry and exit.

[0012] During testing, only two test leads connected to the insulation resistance tester need to be connected to the central junction box to achieve the measurement.

[0013] Preferably, the insulation resistance tester is a programmable insulation resistance tester that supports two test modes: voltage test and step voltage diagnostic test.

[0014] The step voltage diagnostic test includes at least several levels of test voltage from low to high, which can automatically step up the voltage test according to a preset time sequence and maintain a certain stable time. Preferably, in the step voltage diagnostic test mode, the insulation resistance tester automatically increases the test voltage in preset steps, records the insulation resistance value at each voltage point, and automatically plots the resistance-voltage curve.

[0015] Preferably, the step voltage diagnostic test includes at least two test voltage levels of 500V and 1000V, which can automatically step up the voltage according to a preset time sequence and maintain a stable time, with each voltage level holding time being no less than 30s or 60s.

[0016] The above-mentioned step voltage diagnostic test has an insulation resistance abnormality monitoring function. When the insulation resistance drops suddenly at a certain voltage level, it automatically stops the voltage increase and outputs a warning signal.

[0017] An insulation monitoring module is fixedly connected inside the centralized junction box. The insulation monitoring module is connected to each high-voltage test terminal through a high-voltage isolation resistor to collect the insulation resistance data of each point to the end plate in real time.

[0018] The aforementioned insulation monitoring module is equipped with a communication interface to upload data to the central control room, enabling real-time data display, recording of historical trend curves, and alarm functions.

[0019] The insulation monitoring module has two alarm thresholds: the first alarm threshold is 10MΩ, indicating a decrease in insulation and requiring inspection; the second alarm threshold is 2MΩ, indicating an insulation hazard and recommending immediate shutdown.

[0020] Considering that both ends of the electrolytic cell are equipped with end pressure plates and end electrode plates, low-voltage test terminals can be installed on the end pressure plates at both ends, and the measurement can be switched via a dual-channel changeover switch. The high-voltage test terminals on the end electrode plates at both ends can be connected to a multi-channel changeover switch.

[0021] Preferably, the busbar is an arc-shaped strip busbar fixed to an insulating plate. A conductive socket is provided on one side of the high-voltage selection terminal. The arc-shaped strip busbar has a number of conductive pins. A guide post is provided inside the centralized junction box. The insulating plate is movably mounted on the guide post. When the insulating plate moves closer to the conductive socket, each conductive pin of the arc-shaped strip busbar fixed to the insulating plate can be inserted into the corresponding conductive socket, thereby short-circuiting all the high-voltage selection terminals together to achieve overall total resistance measurement. When the insulating plate moves away from the conductive socket, each conductive pin of the arc-shaped strip busbar fixed to the insulating plate can be pulled out from the conductive socket, thereby making each high-voltage selection terminal independent and achieving point resistance measurement.

[0022] Preferably, the centralized junction box is equipped with a servo telescopic device, and the insulating plate is fixedly connected to the telescopic shaft of the servo telescopic device; the servo telescopic device is also connected to the insulation monitoring module, and the insulation monitoring module drives the insulating plate to move through the servo telescopic device, thereby driving the online automatic insertion and removal of the conductive pins and conductive sockets, thereby realizing the online automatic switching between overall total resistance measurement and individual point resistance measurement.

[0023] Preferably, the centralized junction box can be equipped with a drive button for the servo telescopic device to enable manual plugging and unplugging of the conductive pins and conductive sockets, facilitating manual measurement after the insulation resistance tester is connected.

[0024] A test method for an insulation resistance testing system for an electrolytic cell end plate assembly includes the following test contents: The overall insulation rapid test involves short-circuiting all high-voltage test terminals through the busbar and measuring the overall insulation resistance of the terminal plate to all high-voltage terminal components. Insulation fault location is achieved by sequentially selecting each high-voltage test terminal using a multi-way switch and measuring the insulation resistance of the terminal plate to each part of the component. Step voltage diagnostic test involves applying a progressively increasing DC voltage to a specific part and determining its insulation status based on the resistance-voltage curve.

[0025] A test method for an insulation resistance testing system for an electrolytic cell end plate assembly includes the following steps: Step S0: Test Preparation The electrolytic cell's tie rod, tie rod bolt, end plate, and grounding bracket are used as high-voltage test terminals, with high-voltage test leads led out and connected to a centralized junction box; the end plate is used as a non-energized low-voltage test terminal, with its leads connected to the centralized junction box. Connect the low-voltage input terminal of the insulation resistance tester to the low-voltage common terminal (terminal plate) in the central junction box; connect the high-voltage output terminal of the insulation resistance tester to the output terminal of the multiplexer in the central junction box. Step S1: Rapid Overall Insulation Test By short-circuiting all high-voltage test terminals through the busbar in the centralized junction box, the insulation resistance tester measures the overall insulation resistance Rtotal of the terminal plate to all high-voltage components (terminal plates, tie rod bolts, grounding brackets, etc.); if Rtotal is greater than the first threshold, the overall insulation is deemed qualified; if Rtotal is less than the first threshold, proceed to step S3 for fault location.

[0026] Step S2: Locating insulation faults at different points Disconnect the shorting bar, and use the multiplexer to sequentially select each high-voltage test terminal. Measure the insulation resistance of the end plate to the following points: insulation resistance R1 between the end plate and the end electrode plate, insulation resistance R2i (i=1, 2, ..., n) between the end plate and each tie rod bolt, and insulation resistance R3 between the end plate and the grounding bracket. Compare the measured values ​​at each point with the second threshold value to locate the weak insulation point. Step S3: Step voltage diagnostic test For the weak points or key monitoring areas found in step S2, apply a progressively increasing DC voltage and record the insulation resistance value at each voltage point. The insulation status is judged based on the shape of the resistance-voltage curve. A stable curve indicates good insulation, while a declining curve indicates damp or contaminated insulation. A sudden drop in the curve indicates the presence of a hidden breakdown path or crack.

[0027] Preferably, the first threshold is 1 megohm and the second threshold is 5 megohm; in the step voltage diagnostic test, the starting voltage is 500V, the step size is 100V, and the termination voltage is 2000V or until breakdown.

[0028] In step S2, if an abnormal insulation resistance is found in a tie rod bolt, the cause of the fault is further determined by the following method: switch the high voltage end of the insulation resistance tester to the adjacent normal bolt, and measure the insulation resistance between the abnormal bolt and the normal bolt. If the value is low, it is determined that the fault may be caused by the connection between the bolts (such as electrolyte bridging); if the value is normal, it is determined that the fault is caused by the damage to the insulation sleeve of the bolt itself.

[0029] As a further improvement of the present invention, the centralized junction box is also provided with a pulse current transformer for more clearly determining whether the abnormal insulation resistance is caused by early micro-cracks. The signal output line of the pulse current transformer is connected to the analog signal port of the insulation monitoring module. The connection line of the high voltage test terminal to the insulation monitoring module passes through the pulse current transformer and is then connected to the insulation monitoring module through the high voltage isolation resistor.

[0030] Preferably, a pulse current transformer can be set up for each connection line connected to the high-voltage test terminal of the insulation monitoring module to achieve independent diagnosis of microcrack location.

[0031] Alternatively, the connecting lines of each high-voltage test terminal to the insulation monitoring module can be connected together and pass through the pulse current transformer, and then combined with point insulation fault location or step voltage diagnostic test to determine the specific location of microcracks.

[0032] Early warning diagnosis of microcracks: When a local microcrack appears in a conductive component of an electrolytic cell, the high voltage will cause a hidden high voltage discharge phenomenon at the microcrack, which will form a pulse current in the detection circuit, thus indicating that an early microcrack defect has appeared at a certain location.

[0033] The aforementioned early warning diagnosis of microcracks can be performed as an independent detection step, or it can be arranged after the step voltage diagnosis test in step S3 (as step S4). When sharing a single pulse current transformer (for cost reduction), combined with point insulation fault location or step voltage diagnosis test, the conductive components with microcracks can be accurately located, enabling early warning of microcracks in the electrolytic cell and preventing safety accidents caused by the expansion of microcrack hazards.

[0034] The beneficial effects of this invention are: 1. The test potential conforms to the operation and maintenance habits: The terminal block is set to the low voltage common terminal, which simulates the actual wiring method on site (the terminal block is usually grounded). This makes it easier for testers to understand and operate, and the test results are more in line with the actual operating conditions.

[0035] 2. Fixed test points and extremely simple operation: Using pre-set low-voltage and high-voltage terminals, testers only need to plug in the tester and rotate the selector switch to perform multi-point testing. There is no need to temporarily locate test points. Operation is simple, testing efficiency is high, and it is suitable for batch factory inspection and long-term on-site maintenance.

[0036] 3. Quickly locate faulty components: By conducting point-by-point tests, it is possible to accurately locate whether the insulation of the terminal plate has deteriorated, which tie rod bolt has broken insulation, or whether the insulation of the grounding bracket is abnormal, which greatly shortens the troubleshooting time.

[0037] 4. Combination of overall screening and precise location: The busbar design enables one-time overall testing to quickly determine the overall insulation status; the multi-way transfer switch enables point testing to accurately locate faults, and the combination of the two meets different testing needs.

[0038] 5. Detectable latent defects: The step voltage diagnostic test mode can detect latent defects such as moisture and cracks that cannot be detected by traditional fixed voltage tests. It can detect early insulation defects and aging, provide early warning of insulation faults, and avoid sudden shutdowns.

[0039] 6. Strong data comparability: Since the test points are fixed, the test data from each test are highly comparable, which can establish the trend of insulation condition changes and realize predictive maintenance.

[0040] 7. Expandable to online monitoring: By adding an insulation monitoring module, the insulation status of the end pressure plate assembly can be monitored in real time, the insulation degradation trend can be detected in time, and major failures can be avoided.

[0041] 8. Early warning of microcracks: Equipped with a pulse current transformer, it can provide early warning of early hidden microcracks that appear during the operation of the electrolytic cell, further improving the safety of the electrolytic cell. Attached Figure Description

[0042] Figure 1 This is a schematic diagram illustrating the working principle of an insulation resistance testing system for an electrolytic cell end pressure plate assembly according to the present invention. Figure 2 yes Figure 1 The diagram shows the structure involving the connection between the high-voltage selection terminal and the busbar. Figure 3 yes Figure 2 AA view; Figure 4 Is Figure 1 A further improved structural diagram based on the existing design; Figure 5 This is a schematic diagram of the test process for an insulation resistance testing system for an electrolytic cell end pressure plate assembly according to the present invention.

[0043] In the diagram: 10. Electrolytic cell; 11. End plate assembly; 12. End plate body; 13. End plate; 14. Insulation layer; 15. Tie rod bolt; 16. Grounding bracket; 17. Low-voltage test terminal; 18. High-voltage test terminal; 19. First high-voltage test terminal; 20. Second high-voltage test terminal; 21. Third high-voltage test terminal (test ring); 22. End plate tab; 23. High-voltage isolation resistor; 24. Centralized junction box; 25. Insulation resistance tester; 26. High-voltage output terminal; 27. Low-voltage input terminal; 28. Low-voltage common terminal (L1, L2); 29. ​​High-voltage selection terminal (H1~H7); 30. Multiplexer switch; 31. Busbar; 32. Desiccant chamber; 33. Waterproof sealing joint; 34. Insulation monitoring module; 35. Dual-channel switch; 36. Cover; 37. Expansion joint; 38. Guide post. 39. Conductive pin; 40. Conductive socket; 41. Insulating plate for busbar fixing; 42. Pulse current transformer. Detailed Implementation

[0044] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0045] Example 1: like Figures 1 to 5 The diagram shows an overall embodiment of an insulation resistance testing system for an electrolytic cell end plate assembly according to the present invention, comprising: Electrolytic cell end plate assembly 11 includes: end plate body 12; end plate 13 disposed inside the end plate body 12 and having an insulating layer 14 between it and the end plate body 12; a plurality of tie rod bolts 15 penetrating the end plate body 12 for pressing the entire electrolytic cell stack; and a grounding bracket 16 insulated from the end plate body 12 for connecting to the grounding system. The test terminals include a low-voltage test terminal 17, which is disposed on the end plate body 12 and electrically connected to the metal part of the end plate body 12; and a plurality of high-voltage test terminals 18, including a first high-voltage test terminal 19, a second high-voltage test terminal 20, and a third high-voltage test terminal 21; wherein, the first high-voltage test terminal 19 is provided on the end plate 13, the second high-voltage test terminal 20 is provided on the grounding bracket 16, and each tie rod bolt 15 is provided with an independent third high-voltage test terminal 21; each high-voltage test terminal 18 is electrically connected to the metal part of the corresponding component, and the end plate body 12 is kept insulated from its components; The low-voltage test terminal 17 and each high-voltage test terminal 18 are all connected to the central junction box 24 through leads; The insulation resistance tester 25 has a high-voltage output terminal 26 and a low-voltage input terminal 27. The high-voltage output terminal 26 can be selectively connected to any high-voltage test terminal 18, and the low-voltage input terminal 27 is connected to the low-voltage test terminal 17. The insulation resistance tester 25 includes two test modes: voltage test and step voltage diagnostic test.

[0046] Preferably, the low-voltage test terminal 17 is arranged on the side or top of the end plate body 12, adopts a recessed structure, its contacts are recessed into the surface of the end plate, and a self-closing dust cover is arranged at the opening.

[0047] Preferably, the first high-voltage test terminal 19 on the end plate 13 is fixed to the tab 22 of the end plate and connected to the end plate 13 through a high-voltage isolation resistor 23. The high-voltage isolation resistor 23 has a resistance of 1-10MΩ and is used to isolate high voltage during normal operation of the electrolytic cell and limit the voltage / current of the test terminal to a safe range.

[0048] Preferably, the third high-voltage test terminal 21 on the tie rod bolt 15 is a test ring fitted onto the bolt head. Each test ring is connected to the central junction box 24 via an independent lead wire. The test ring is in metal contact with the bolt head but is insulated from the end pressure plate.

[0049] Preferably, the centralized junction box 24 has a waterproof, dustproof, and electric shock-proof structure, and contains: a low-voltage common terminal 28 connected to the low-voltage test terminal 17 of the end plate body 12; multiple high-voltage selection terminals 29 connected to each high-voltage test terminal 18; a multi-way switch 30 for switching between the multiple high-voltage selection terminals 29 to connect the selected high-voltage test terminal 18 to the high-voltage output terminal 26 of the insulation resistance tester; a busbar 31 for short-circuiting all high-voltage test terminals 18 for overall testing; a desiccant chamber 32 containing color-changing silica gel desiccant; and a waterproof sealing joint 33 for lead wire entry and exit.

[0050] During testing, only two test leads connected to the insulation resistance tester 25 need to be connected to the central junction box 24 to achieve the measurement.

[0051] Preferably, the insulation resistance tester 25 is a programmable insulation resistance tester that supports two test modes: voltage test and step voltage diagnostic test.

[0052] The step voltage diagnostic test includes at least several levels of test voltage from low to high, which can automatically step up the voltage test according to a preset time sequence and maintain a certain stable time. Preferably, in the step voltage diagnostic test mode, the insulation resistance tester 25 automatically increases the test voltage in preset steps, records the insulation resistance value at each voltage point, and automatically plots the resistance-voltage curve.

[0053] Preferably, the step voltage diagnostic test includes at least two test voltage levels of 500V and 1000V, which can automatically step up the voltage according to a preset time sequence and maintain a stable time, with each voltage level holding time being no less than 30s or 60s.

[0054] The above-mentioned step voltage diagnostic test has an insulation resistance abnormality monitoring function. When the insulation resistance drops suddenly at a certain voltage level, it automatically stops the voltage increase and outputs a warning signal.

[0055] An insulation monitoring module 34 is fixedly connected inside the centralized junction box 24. The insulation monitoring module 34 is connected to each high-voltage test terminal 18 through a high-voltage isolation resistor 23 to collect insulation resistance data of each point to the end plate in real time.

[0056] The aforementioned insulation monitoring module 34 is equipped with a communication interface to upload data to the central control room, enabling real-time data display, recording of historical trend curves, and alarm functions.

[0057] The insulation monitoring module 34 has two alarm thresholds: the first alarm threshold is 10MΩ, indicating a decrease in insulation and requiring inspection; the second alarm threshold is 2MΩ, indicating an insulation hazard and recommending immediate shutdown.

[0058] Considering that both ends of the electrolytic cell 10 are equipped with end pressure plates and end electrode plates 13, low-voltage test terminals 17 can be installed on the end pressure plates at both ends, and the measurement can be switched through a dual-channel changeover switch 35. The high-voltage test terminals 18 of the end electrode plates 13 at both ends can be connected to the multiplexer switch 30 respectively.

[0059] Preferably, the busbar 31 is an arc-shaped strip busbar 31, which is fixed on the busbar fixing insulating plate 41. A conductive socket 40 is provided on one side of the high-voltage selection terminal 29. A number of conductive pins 39 are provided on the arc-shaped strip busbar 31. A guide post 38 is provided inside the centralized junction box 24. The busbar fixing insulating plate 41 is movably mounted on the guide post 38. When the busbar fixing insulating plate 41 moves towards the conductive socket 40, it is fixed on the busbar fixing insulating plate 41. Each conductive pin 39 of the arc-shaped strip busbar 31 on the insulating plate 41 can be inserted into the corresponding conductive socket 40, thereby short-circuiting all the high-voltage selection terminals 29 together to achieve overall total resistance measurement; when the busbar fixing insulating plate 41 moves away from the conductive socket 40, each conductive pin 39 of the arc-shaped strip busbar 31 fixed on the busbar fixing insulating plate 41 can be pulled out from the conductive socket 40, thereby making each high-voltage selection terminal 29 independent of each other to achieve point resistance measurement.

[0060] Preferably, the centralized junction box 24 is provided with an expansion joint 37, and the busbar fixing insulating plate 41 is fixedly connected to the expansion shaft of the expansion joint 37; the expansion joint 37 is also connected to the insulation monitoring module 34, and the insulation monitoring module 34 drives the busbar fixing insulating plate 41 to move through the expansion joint 37, thereby driving the online automatic insertion and removal of the conductive pins 39 and the conductive sockets 40, thereby realizing the online automatic switching between overall total resistance measurement and individual point resistance measurement.

[0061] Preferably, the centralized junction box 24 may be equipped with a drive button for the telescopic device 37 to facilitate manual insertion and removal of the conductive pins 39 and the conductive socket 40, thus enabling manual measurement after the insulation resistance tester 25 is connected.

[0062] A test method for an insulation resistance testing system for an electrolytic cell end plate assembly includes the following test contents: The overall insulation rapid test involves shorting all high-voltage test terminals 18 through busbar 31 and measuring the overall insulation resistance of the terminal plate to all high-voltage terminal components. For point insulation fault location, the high voltage test terminals 18 are selected sequentially by the multiplexer 30 to measure the insulation resistance of the end plate to each part of the component. Step voltage diagnostic test involves applying a progressively increasing DC voltage to a specific part and determining its insulation status based on the resistance-voltage curve.

[0063] A test method for an insulation resistance testing system for an electrolytic cell end plate assembly includes the following steps: Step S0: Test Preparation The tie rod, tie rod bolt 15, terminal plate 13, and grounding bracket 16 of the electrolytic cell 10 are used as high-voltage test terminals 18, and high-voltage test leads are led out and connected to the centralized junction box 24. The terminal pressure plate is used as a non-energized low-voltage test terminal 17, and the lead is connected to the centralized junction box 24. Connect the low-voltage input terminal 27 of the insulation resistance tester 25 to the low-voltage common terminal terminal 28 (terminal pressure plate) in the centralized junction box 24; connect the high-voltage output terminal 26 of the insulation resistance tester 25 to the output terminal of the multiplexer 30 in the centralized junction box 24. Step S1: Rapid Overall Insulation Test By shorting all high-voltage test terminals 18 through the busbar 31 in the central junction box 24, the insulation resistance tester 25 measures the overall insulation resistance R_total of all high-voltage components (terminal plate 13, each tie rod bolt 15, grounding bracket 16, etc.) of the terminal plate; if R_total is greater than the first threshold, the overall insulation is deemed qualified; if R_total is less than the first threshold, proceed to step S3 for fault location.

[0064] Step S2: Locating insulation faults at different points Disconnect the shorting bar, and use the multiplexer 30 to sequentially select each high-voltage test terminal 18. Measure the insulation resistance of the end plate to the following points: insulation resistance R1 between the end plate and the end electrode 13, insulation resistance R2i (i=1, 2, ..., n) between the end plate and each tie rod bolt 15, and insulation resistance R3 between the end plate and the grounding bracket 16. Compare the measured values ​​at each point with the second threshold value to locate the weak insulation point. Step S3: Step voltage diagnostic test For the weak points or key monitoring areas found in step S2, apply a progressively increasing DC voltage and record the insulation resistance value at each voltage point. The insulation status is judged based on the shape of the resistance-voltage curve. A stable curve indicates good insulation, while a declining curve indicates damp or contaminated insulation. A sudden drop in the curve indicates the presence of a hidden breakdown path or crack.

[0065] Preferably, the first threshold is 1 megohm and the second threshold is 5 megohm; in the step voltage diagnostic test, the starting voltage is 500V, the step size is 100V, and the termination voltage is 2000V or until breakdown.

[0066] In step S2, if an abnormal insulation resistance is found in a certain tie rod bolt 15, the cause of the fault is further determined by the following method: switch the high voltage end of the insulation resistance tester 25 to the adjacent normal bolt, measure the insulation resistance between the abnormal bolt and the normal bolt. If the value is low, it is determined that the fault may be caused by the connection between the bolts (such as electrolyte bridging); if the value is normal, it is determined that the fault is caused by the damage to the insulation sleeve of the bolt itself.

[0067] As a further improvement of this embodiment, the centralized junction box 24 is also provided with a pulse current transformer 42 for more clearly determining whether the abnormal insulation resistance is caused by early micro-cracks. The signal output line of the pulse current transformer 42 is connected to the analog signal port of the insulation monitoring module 34. The connection line of the high voltage test terminal 18 to the insulation monitoring module 34 passes through the pulse current transformer 42 and then through the high voltage isolation resistor 23 to the insulation monitoring module 34.

[0068] Preferably, a pulse current transformer 42 can be set for each connection line connected to the high voltage test terminal 18 of the insulation monitoring module 34 to achieve independent diagnosis of microcrack location.

[0069] Alternatively, the connecting lines of each high-voltage test terminal 18 to the insulation monitoring module 34 can be connected together and pass through the pulse current transformer 42, and then combined with point insulation fault location or step voltage diagnostic test to determine the specific location of microcracks.

[0070] Early warning diagnosis of microcracks: When a local microcrack appears in a conductive component of the electrolytic cell 10, the high voltage will cause a hidden high voltage discharge phenomenon at the local microcrack, which will form a pulse current in the detection circuit, thus indicating that an early microcrack defect has appeared at a certain place.

[0071] The aforementioned early warning diagnosis of microcracks can be performed as an independent detection step, or it can be arranged after the step voltage diagnosis test in step S3 (as step S4). When sharing a single pulse current transformer 42 (for cost reduction), combined with point insulation fault location or step voltage diagnosis test, the conductive parts with microcracks can be accurately located, achieving early warning of microcracks in the electrolytic cell 10 and preventing safety accidents caused by the expansion of microcrack hazards.

[0072] Example 2: Insulation Testing System for End Plate Assembly of Chlor-Alkali Electrolyzer System Structure This embodiment is applied to alkaline electrolytic cell 10. The end plate assembly 11 and the testing system are manufactured according to the following structure: Low-voltage test terminal 17 of the end plate: The end plate bodies 12 at both ends are made of Q235B steel plate with a thickness of 30mm and a size of 1500mm×800mm. A countersunk hole with a diameter of 20mm and a depth of 15mm is opened on the outer side or top of the end plate. A raised conductive contact is provided at the center of the bottom of the hole, which is connected to the end plate body 12. A recessed low-voltage test terminal 17 is installed in the countersunk hole, with the terminal contact located at the bottom of the countersunk hole. A self-closing dust cover is installed at the opening of the countersunk hole, which is only opened when the test lead plug is inserted. The lead is made of corrosion-resistant PTFE insulated wire and is connected to the centralized junction box 24, labeled "COM" ("COM1", "COM2").

[0073] High-voltage test terminal 18 on the terminal plate: The terminal plate 13 is located inside the end pressure plate, with a 15mm thick epoxy glass cloth insulation layer 14 between them. An M8 copper terminal is installed on the tab 22 of the terminal plate as the high-voltage test terminal 18. The terminal is metal-conductive to the tab but insulated from the end pressure plate. To ensure safety during normal operation, a 5MΩ high-voltage isolation resistor 23 is connected in series between the terminal and the tab, encapsulated in a small insulating box. Leads are connected to the central junction box 24, labeled "EP" ("EP1", "EP2").

[0074] High-voltage test terminal 18 for tie rod bolts: This embodiment has four M30 tie rod bolts 15. Each bolt head is fitted with an insulating test ring (third high-voltage test terminal 21). The test ring is made of copper, with an inner diameter matching the bolt head and an outer diameter of 20mm. The test ring is in metal-to-metal contact with the bolt head but insulated from the end pressure plate. A protective cover is installed on the outside of the test ring. Independent leads are led from the test ring to the centralized junction box 24, labeled "B1", "B2", "B3", and "B4" respectively.

[0075] High voltage test terminal 18 of grounding bracket: Next to the grounding bolt of grounding bracket 16, add an M8 copper terminal, which is connected to the bracket but insulated from the end plate, labeled "GND", and leads to the central junction box 24.

[0076] Centralized junction box 24: Installed on the side of the end pressure plate, it adopts an explosion-proof design with an IP65 protection rating. The centralized junction box 24 contains two low-voltage common terminal blocks 28 (L1 and L2), which are connected to the low-voltage test terminals 17 "COM" on both sides of the end pressure plates of the electrolytic cell 10. It also contains seven high-voltage selection terminals 29, which are connected to the end plates 13 on both sides of the electrolytic cell 10, four tie rod bolts 15, and grounding brackets 16 ("EP1", "EP2", "B1", "B2", "B3", "B4", "GND").

[0077] 30-way selector switch: 7-position rotary switch with positioning knob, which can sequentially select any high-voltage terminal output to the high-voltage end of the tester.

[0078] Busbar 31: All high-voltage terminals can be shorted at once by manual or button operation.

[0079] Waterproof sealing connector 33: PG16 specification, for lead wire entry and exit.

[0080] Insulation Resistance Tester 25: Programmable Insulation Tester, Technical Parameters: Test voltage is adjustable from 100V to 250V, 500V, and 1000V, and the step mode can be stepped in 100V increments.

[0081] Dedicated test lead cable: 5 meters in length, one end is the standard interface of the tester (with locking function), and the other end is split into two paths: one is a low-voltage plug, which connects to the low-voltage test terminal 17 "COM" ("COM1" or "COM2") of the central junction box 24 via a dual-channel changeover switch 35; the other is a high-voltage plug, which connects to the output terminal of the multi-channel changeover switch 30 of the central junction box 24. The cable is insulated with silicone rubber, temperature resistant from -40℃ to 200℃, and resistant to oil and corrosion.

[0082] Insulation resistance test After the electrolytic cell 10 is assembled, the insulation resistance is tested according to the method in Example 1.

[0083] Step S0: Test Preparation Open the central junction box 24 and check the color of the desiccant (blue is normal, pink requires replacement). Insert the low-voltage plug of the tester into the "COM" terminal and the high-voltage plug into the output terminal of the multiplexer 30. Check that all connections are secure.

[0084] Step S1: Rapid Overall Insulation Test Push the busbar 31 in the central junction box 24 to the "short-circuit" position and short-circuit all high-voltage test terminals 18 (EP, B1-B4, GND). Set the tester to 1000V fixed voltage mode, start the test, and read the value after 60 seconds. The measured R_total = 78MΩ, which is greater than the first threshold of 1MΩ, so the overall insulation is deemed qualified.

[0085] Step S2: Point insulation test (verification test) Disconnect busbar 31 (reset busbar 31 to its original position), and rotate the multiplexer switch 30 to each position in sequence. After each position stabilizes, read the value: rotate to "EP" (terminal plate 13) for R1=120MΩ, rotate to "B1" for R21=95MΩ, rotate to "B2" for R22=88MΩ, rotate to "B3" for R23=92MΩ, rotate to "B4" for R24=90MΩ, and rotate to "GND" (grounding bracket 16) for R3=450MΩ.

[0086] All values ​​are greater than the second threshold of 5MΩ, indicating good insulation. Record the data and archive it.

[0087] Step S3: Step voltage diagnostic test (deep detection of key areas) Turn the selector switch to "EP" (terminal plate 13) to set the step voltage mode. The starting voltage is 500V, the step size is 100V, and the ending voltage is 1000V. The hold time for each point is 60 seconds. The tester will automatically perform the test and record the resistance value at each voltage point. 500V corresponds to 120MΩ, 600V corresponds to 120.5MΩ, 700V corresponds to 119.8MΩ, 800V corresponds to 120.2MΩ, 900V corresponds to 119.5MΩ, and 1000V corresponds to 120.1MΩ.

[0088] The plotted curve shows a stable trend with no downward trend, indicating good insulation. The entire test process takes approximately 10 minutes, requiring no movement of the test position, no repeated clamping of the meter, and no grinding of any test points.

[0089] Example 3: Fault Simulation and Rapid Location To verify the fault location capability of the present invention, a simulated fault was set up: a small crack was artificially created on the insulating sleeve of the tie rod bolt 15B3.

[0090] Step S2 Overall Test: Short-circuit all high-voltage terminals and measure R_total = 0.8MΩ, which is less than the 1MΩ threshold. It is determined that there is an insulation fault, and proceed to step S3.

[0091] Step S3: Point-by-point test: Remove the shorting bar and rotate the multiplexer switch 30 in sequence. "EP" reading: 118 MΩ (normal); "B1" reading: 92 MΩ (normal); "B2" reading: 89 MΩ (normal); "B3" reading: 0.3 MΩ (abnormal); "B4" reading: 91 MΩ (normal); "GND" reading: 420 MΩ (normal). Quickly locate the fault: Insulation failure of bolt 15 on tie rod B3.

[0092] Step S4 Step Voltage Diagnosis (Deep Inspection of B3): Turn the selector switch to "B3" and set the step voltage mode (500V-1000V, step size 100V): 500V corresponds to 0.3MΩ, 600V corresponds to 0.28MΩ, 700V corresponds to 0.25MΩ, 800V corresponds to 0.15MΩ (starting to decrease), 900V corresponds to 0.04MΩ (sudden drop), and 1000V corresponds to breakdown (0MΩ). The curve shows typical latent defect characteristics, confirming the presence of a crack.

[0093] Auxiliary Diagnosis: To further confirm the cause of the fault, the selector switch was turned to the adjacent normal bolt "B2," and the insulation resistance between B3 and B2 was measured: the resistance of B3 to B2 was measured to be 450MΩ, which is normal. This indicates that the fault originated from damage to the insulation sleeve of bolt B3 itself, rather than a connection between bolts. Disassembly and inspection revealed a small crack in the insulation sleeve of bolt B3; after replacement, the fault was resolved. The entire positioning process only takes 15 minutes and does not require individual disassembly and inspection.

[0094] Example 4: One of the applications of online insulation monitoring Based on Example 2, an insulation monitoring module 34 is added to the centralized junction box 24 to form an online monitoring system.

[0095] Insulation monitoring module 34 parameters: Model: IM1000; Operating voltage: DC 24V (powered from the control system of electrolytic cell 10); Measures EP, B1-B4, and GND respectively. Principle: DC injection method, injection current <1mA, does not affect the operation of electrolytic cell 10; Measurement range: 0.1MΩ - 1000MΩ; Accuracy: ±5%; Sampling period: configurable (1 second - 1 hour); Communication interface: RS485, Modbus RTU protocol; Alarm output: Two relays, two alarm thresholds can be set; Installation and operation: The module is connected to each high-voltage test terminal 18 through high-voltage isolation resistor 23 (5MΩ) to collect the insulation resistance data of each point to the end plate in real time. The module uploads the data to the central control room DCS system via RS485 bus. Central control room monitoring interface: Real-time display of insulation resistance values ​​at various points, presented intuitively in the form of a bar chart; Historical trend curves, showing changes over 24 hours, 7 days, and 30 days; Alarm records: Records the time, channel, and value of each alarm; Report generation: Automatically generates daily insulation test reports.

[0096] Operational Results: Three months after commissioning, the system detected that the insulation resistance of terminal plate 13 (EP) channel gradually decreased from 120MΩ to 45MΩ. Although still above the alarm threshold, the downward trend was significant. Maintenance personnel in the central control room inspected the system and found a small amount of electrolyte crystallization on the surface of the insulation plate between terminal plate 13 and the end plate. After cleaning, the resistance returned to 115MΩ. Because the problem was detected and addressed early, a potential insulation breakdown accident was avoided.

[0097] Example 5: Application of Online Insulation Monitoring (Part Two) The only difference from Embodiment 4 is that the insulation monitoring module 34 detects the presence of pulse current on the connection line of the high-voltage test terminal 18 connected to the insulation monitoring module 34 through the pulse current sensor, issues an early warning, and then performs a fusion diagnosis through point insulation fault location and step voltage diagnostic test to determine that there is an early hidden micro-crack in the right end plate 13. The safety hazard is avoided by replacing the right end plate 13 in time.

[0098] This embodiment constructs a simple and efficient insulation resistance testing system by setting the terminal pressure plate as the low-voltage common terminal and the terminal plate 13, each tie rod bolt 15, and the grounding bracket 16 as high-voltage test points. The main innovations include: Structural innovation: Pre-set test terminals concentrate scattered test points into the junction box, making the test points fixed and standardized.

[0099] Methodological innovation: A three-tiered testing process was established, consisting of "overall rapid screening - precise point positioning - step-by-step in-depth diagnosis," balancing efficiency and accuracy.

[0100] Functional innovation: The shorting bar enables rapid overall testing, while the multi-channel changeover switch 30 enables convenient point-by-point testing. The combination of the two meets different needs.

[0101] Diagnostic innovation: Step voltage testing can detect latent defects, and auxiliary judgment can further clarify the cause of the fault.

[0102] Extended Innovation: It can be upgraded to an online monitoring system to achieve real-time monitoring and trend early warning. Through a fusion diagnostic method combining point insulation fault location, step voltage diagnostic testing, and early warning diagnosis of microcracks, the operational safety of electrolytic cell 10 is improved.

[0103] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An insulation resistance testing system for an electrolytic cell end plate assembly, characterized in that, include: The end plate assembly includes an end plate body, an end plate, multiple tie rod bolts, and a grounding bracket; The test terminals include low-voltage test terminals and multiple high-voltage test terminals. The low-voltage test terminals are fixedly mounted on the end pressure plate body and are electrically connected to the metal part of the end pressure plate body. Multiple high-voltage test terminals are respectively disposed on the end plate, each tie rod bolt and grounding bracket. Each high-voltage test terminal is electrically connected to the corresponding metal part of the component and is insulated from the end plate body and other components. A centralized junction box, in which the leads of the low-voltage test terminals and each high-voltage test terminal are all connected and converged into the interior of the centralized junction box; The insulation resistance tester has a high-voltage output terminal and a low-voltage input terminal. The high-voltage output terminal can be selectively connected to any high-voltage test terminal, and the low-voltage input terminal is connected to the low-voltage test terminal. The insulation resistance tester supports two modes: fixed voltage testing and step voltage diagnostic testing.

2. The insulation resistance testing system for an electrolytic cell end pressure plate assembly according to claim 1, characterized in that, The low-voltage test terminal adopts a recessed structure, is arranged on the side or top of the end pressure plate body, and is equipped with a self-closing dust cover.

3. The insulation resistance testing system for an electrolytic cell end pressure plate assembly according to claim 1, characterized in that, The high-voltage test terminal on the terminal plate is connected to the terminal plate through a high-voltage isolation resistor.

4. The insulation resistance testing system for an electrolytic cell end pressure plate assembly according to claim 3, characterized in that, The resistance of the high-voltage isolation resistor is 1-10MΩ.

5. The insulation resistance testing system for an electrolytic cell end pressure plate assembly according to claim 1, characterized in that, The high-voltage test terminals on the tie rod bolts are all test rings fitted onto the bolt heads, and each test ring is connected to a central junction box via an independent lead wire.

6. The insulation resistance testing system for an electrolytic cell end pressure plate assembly according to claim 1, characterized in that, The centralized junction box is a waterproof, dustproof, and shockproof junction box. It is equipped with a low-voltage common terminal, multiple high-voltage selection terminals, a multi-way changeover switch, and a busbar. All test terminal leads are connected to the busbar inside the centralized junction box to achieve synchronous high- and low-voltage access to the terminal pressure plate, tie rod bolt, terminal plate, and grounding bracket. During testing, the measurement can be achieved by connecting two test leads to the insulation resistance tester on the centralized junction box.

7. The insulation resistance testing system for an electrolytic cell end pressure plate assembly according to claim 1, characterized in that, An insulation monitoring module is fixedly connected inside the centralized junction box. The insulation monitoring module is connected to each high-voltage test terminal through a high-voltage isolation resistor to capture the insulation resistance data of each point to the end plate in real time. The insulation monitoring module is equipped with a communication interface and uploads the data to the central control room. It has the functions of real-time data display, historical trend record retrieval, and alarm.

8. The insulation resistance testing system for an electrolytic cell end pressure plate assembly according to claim 7, characterized in that, The insulation monitoring module has two alarm thresholds, namely 10MΩ and 2MΩ.

9. The insulation resistance testing system for an electrolytic cell end pressure plate assembly according to claim 1, characterized in that, The step voltage diagnostic test includes at least several test voltage levels from low to high, which can automatically increase the voltage level step by step according to a preset time sequence and maintain a certain stable time. The step voltage diagnostic test has an insulation resistance abnormality monitoring function. When the insulation resistance drops suddenly at a certain voltage level, the voltage increase is automatically stopped and an early warning signal is output.

10. The insulation resistance testing system for an electrolytic cell end pressure plate assembly according to claim 9, characterized in that, The step voltage diagnostic test includes at least two test voltage levels: 500V and 1000V; the holding time for each voltage level is not less than 30s or 60s.

11. A test method for an insulation resistance testing system based on the electrolytic cell end plate assembly according to any one of claims 1-10, characterized in that, The test includes the following content: The overall insulation rapid test involves short-circuiting all high-voltage test terminals through the busbar and measuring the overall insulation resistance of the terminal plate to all high-voltage terminal components. Insulation fault location is achieved by sequentially selecting each high-voltage test terminal using a multi-way switch and measuring the insulation resistance of the terminal plate to each part of the component. Step voltage diagnostic test involves applying a progressively increasing DC voltage to a specific part and determining its insulation status based on the resistance-voltage curve.

12. The test method of the insulation resistance test system for an electrolytic cell end pressure plate assembly according to claim 11, characterized in that, In the step voltage diagnostic test, if the resistance-voltage curve is stable, it is determined that the component has good insulation; if the curve drops, it is determined that it is damp or contaminated; if the curve drops sharply, it is determined that the component has a hidden defect.

13. A test method for an insulation resistance testing system based on the electrolytic cell end pressure plate assembly according to any one of claims 1-10, characterized in that, The specific steps include the following: S1. Rapid Overall Insulation Test: The rapid overall insulation test method is used to test the overall insulation resistance of the terminal plate to all high-voltage components; S2. Location of insulation faults at individual points: By measuring the insulation resistance of the end plate to each component through the point insulation fault test method, the weak points of insulation are located. S3. Stepped Voltage Diagnostic Test: Using the stepped voltage diagnostic test method, multiple levels of DC test voltage are applied step by step. At each voltage level, a preset stabilization time is maintained, and the corresponding insulation resistance value is measured and recorded. Based on the values ​​and trends of the insulation resistance at each voltage level, it is determined whether the insulation performance between the end plate and the tie rod bolt, end plate, and grounding bracket is qualified.

14. The test method for the insulation resistance testing system of an electrolytic cell end pressure plate assembly according to claim 11 or 13, characterized in that, Before testing, the electrolytic cell was de-energized, tested for voltage, and fully discharged. After testing, it was discharged again and the equipment was restored to its normal grounding state.

Images