Dissection platform and quantitative analysis method for fault cable terminal

Abstract

The invention discloses a dissecting platform and a quantitative analysis method for a faulty cable terminal. The quantitative analysis method comprises the following steps: placing the faulty cable terminal on the dissecting platform; observing the appearance of the faulty cable terminal, dissecting the faulty cable terminal, and determining a fault feature vector; calculating a fault type judgment characteristic quantity by using the fault characteristic vector and the incidence matrix; and establishing a corresponding relation between different fault type judgment characteristic quantities and cable fault types, taking the corresponding relation as a fault type judgment basis, and judging the cable fault types according to the obtained fault type judgment characteristic quantities. According to the dissection platform and the quantitative analysis method for the faulty cable terminal, the fault analysis difficulty of the cable terminal can be reduced, an accurate fault reason can be obtained, a foundation is laid for further proposing prevention and rectification measures and reducing the fault rate of the cable, and the reliability of a cable line is effectively improved.

Description

Technical Field

[0001] The invention relates to the field of measurement and testing of faulty cable terminals, and in particular to a dissection platform and a quantitative analysis method for faulty cable terminals. Background Art

[0002] With the development of economy and society, cable lines are increasingly widely used in transmission networks due to their advantages such as low land occupation rate. The failure rate of cable lines directly affects the reliability of the entire transmission network. Statistics show that the number of failures of cable terminals is much higher than that of cable bodies and intermediate joints. Cable terminals are mainly divided into oil-filled terminals, dry flexible terminals and GIS terminals, among which the failure rate of dry flexible terminals is much higher than that of the other two types of terminals. In order to prevent the recurrence of similar failures, it is necessary to dissect the faulty dry flexible cable terminals, analyze the causes of the failures, and propose effective detection and prevention methods. Dry flexible cable terminal failures can be divided into 7 types according to their causes: A-surface discharge, B-mechanical damage to cable insulation, C-air gap discharge between stress cone and cable interface, D-lap misalignment between stress cone and cable interface, E-cable insulation degradation, and F-cable insulation quality problems.

[0003] However, there is currently a lack of dedicated dissection platforms, scientific dissection processes, and effective analysis methods for faulty cable terminals:

[0004] 1) Lack of dedicated dissection platform. Faulty cable terminals are often not straight, but rather present a certain bending state, which results in the inability to maintain the ideal dissection position upward during the dissection, observation, and measurement of the cable terminals, increasing the difficulty of dissection and reducing the efficiency of dissection. Therefore, it is urgent to develop a dedicated dissection platform for cable terminals to ensure that the cable terminal posture can be adjusted according to the dissection, observation, and measurement needs of the cable terminals.

[0005] 2) Lack of scientific dissection process. At present, the industry has not clearly defined how to dissect the terminal and what the specific steps are. Dissectors dissect blindly, which leads to the destruction of fault phenomena and changes in the relative position between the cable terminal body and the cable body, making it impossible to observe the complete fault phenomenon and difficult to verify the installation dimensions, which hinders the analysis of the cause of the fault.

[0006] 3) Lack of effective and quantitative analysis methods. There is a lack of scientific guidance on how to obtain the cause of the fault from the complex fault phenomenon. It is urgent to find out the correlation between the fault phenomenon and the fault cause, reduce the difficulty of fault analysis, clarify the cause of the fault, and then put forward targeted prevention and rectification measures to reduce the cable failure rate. Summary of the invention

[0007] In order to solve the deficiencies in the prior art, the present invention provides a dissection platform and quantitative analysis method for faulty cable terminals, which can reduce the difficulty of cable terminal fault analysis and derive the accurate cause of the fault, thereby laying the foundation for further proposing preventive and corrective measures and reducing the cable failure rate, and effectively improving the reliability of the cable line.

[0008] The present invention adopts the following technical solution.

[0009] In a first aspect, the present invention provides a quantitative analysis method for a faulty cable terminal, comprising the following steps: placing the faulty cable terminal on a dissection platform; observing the appearance of the faulty cable terminal and dissecting it, determining the appearance characteristic quantity a of the top seal, the appearance characteristic quantity b of the tail seal, the moisture characteristic quantity c of the internal moisture of the top seal, the moisture characteristic quantity d of the internal moisture of the tail seal, the insulation shielding scar characteristic quantity e of the internal fracture of the metal sheath, the stress cone lap misalignment characteristic quantity f, the breakdown channel characteristic quantity g, the cable insulation shielding fracture treatment condition characteristic quantity h, the cable curvature determining cable curvature characteristic quantity i, the slice electrical tree growth direction characteristic quantity j, the cable body insulation quality problem characteristic quantity k, and the value of the physical and chemical properties test result characteristic quantity m;

[0010] Calculate the fault type judgment feature V = |nP|; where n = [a bc defghjkm],

[0011] The corresponding relationship between the size of the characteristic quantity for judging different fault types and the cable fault type is established as the basis for distinguishing the fault type. The cable fault type is determined according to the size of the characteristic quantity for judging the fault type obtained.

[0012] Preferably, placing the faulty cable terminal on the dissection platform comprises the following steps: cutting the cable terminal at a first distance below the lower edge of the heat shrink tube at the lower end of the faulty cable terminal; placing the two ends of the cut cable terminal on two cable holders of the dissection platform respectively, and placing the end of the cable terminal with the outlet fitting on the cable holder with a locking wheel; aligning the outlet fitting with the pressure block of the locking wheel at a second distance above the upper edge of the crimping part of the cable core; rotating the faulty cable terminal so that the breakdown position faces upward, and locking the locking wheel.

[0013] Preferably, the first distance is 20-200 mm; the second distance is 5 mm-10 mm.

[0014] Preferably, determining the values ​​of the top seal appearance characteristic quantity a and the tail seal appearance characteristic quantity b comprises the following steps: after fixing the faulty cable terminal on the dissection platform, observing the top seal and the tail seal of the cable terminal; if the top seal is torn, a=1 is taken, if there is no tearing, a=0 is taken; if the tail of the terminal is separated from the tail seal or the tail seal has a bulging phenomenon, b=1 is taken, if the tail of the terminal is not separated from the tail seal and the tail seal has no bulging phenomenon, b=0 is taken.

[0015] Preferably, determining the values ​​of the moisture characteristic quantity c inside the top seal, the moisture characteristic quantity d inside the tail seal, and the insulation shielding scratch characteristic quantity e inside the metal sheath fracture includes the following steps: after determining the values ​​of the top seal appearance characteristic quantity a and the tail seal appearance characteristic quantity b, rotating the cable terminal 90° so that the fault breakdown position faces the left or right side, and re-locking the faulty cable terminal; removing the top seal and the tail seal, and observing whether there are signs of moisture inside the top seal and the tail seal; if there are signs of moisture inside the top seal, take c=1, otherwise, take c=0; if there are signs of moisture inside the tail seal, take d=1, otherwise, take d=0; checking whether the insulation shielding inside the metal sheath fracture of the cable body is scratched by knife marks or punctured by metal sheath burrs, if the insulation shielding inside the metal sheath fracture is punctured by metal sheath burrs or scratched by knife marks, take e=1; otherwise, take e=0.

[0016] Preferably, determining the value of the stress cone overlap misalignment characteristic quantity f comprises the following steps: after determining the values ​​of the internal moisture characteristic quantity c of the top seal, the internal moisture characteristic quantity d of the tail seal, and the internal insulation shielding scar characteristic quantity e of the metal sheath fracture, the cable terminal body is cut open along a straight line perpendicular to the cable from the top to the tail, and the overlap depth L between the cable insulation shield and the semi-conductive part of the stress cone inside the terminal is measured for the first time. d ; Rotate the cable terminal 180°, and again cut the cable terminal body from the top to the tail perpendicular to the cable in a straight line, remove the two parts of the cable terminal to expose the cable body; If the first measurement cannot determine L d , then the second measurement L d ; Measure the length L of the semi-conductive buffer section inside the stress cone s ; If L d ≤0 or L d ≥L s -5mm, then f is 1, if 0 <L d <L s -5mm, then f is 0.

[0017] Preferably, determining the value of the breakdown channel characteristic quantity g includes the following steps: after determining the value of the stress cone overlap misalignment characteristic quantity f, checking whether there is a surface discharge channel from the insulation shielding break to the top wire core or a radial breakdown hole on the cable body, and the distance between the center of the breakdown hole and the insulation shielding break of the cable; if there is a surface discharge channel from the insulation shielding break to the top wire core, take g=0; if there is a radial breakdown hole, it is divided into the following three cases: if the breakdown hole is located at the metal sheath break, take g=1; if the center of the breakdown hole is at the insulation shielding break, take g=4; if the center of the breakdown hole is between the insulation shielding break and the upper edge of the semi-conductive buffer section inside the stress cone, take g=3; if the breakdown hole is located at a position other than the above-mentioned position, and the insulation at the breakdown position has obvious color abnormalities or impurities, take g=6.

[0018] Preferably, determining the value of the characteristic quantity h of the cable insulation shielding fracture processing condition includes the following steps: after determining the value of the stress cone lap misalignment characteristic quantity f, checking whether the cable insulation shielding fracture has pits, burrs, and steps; if there are no pits, burrs, and steps, take h=0; otherwise, take h=1.

[0019] Preferably, determining the cable curvature and determining the value of the cable curvature characteristic quantity i include the following steps: after determining the value of the stress cone overlap misalignment characteristic quantity f, measuring the cable curvature θ; when θ<30°, i=0; when θ≥30°, i=1.

[0020] Preferably, determining the values ​​of the characteristic quantity j of the growth direction of the electrical tree in the slice and the characteristic quantity k of the insulation quality problem of the cable body includes the following steps: using a cable stripping knife to cut the cable along the axial stripping breakdown position on both sides of the cable to obtain cable slices, wherein the third distance is less than or equal to 100 mm; observing whether the cable slice has radial electrical trees and the growth direction of the electrical trees, if the electrical trees grow from the outside to the inside, take j=-1; if the electrical trees grow from the inside to the outside, take j=1; if there are no electrical trees, take j=0; observing whether the cable slice has impurities or micropores, if there are no impurities and micropores, take k=0; if there are impurities or micropores, take k=1.

[0021] Preferably, determining the value of the characteristic quantity m of the physical and chemical property test result includes the following steps: after determining the values ​​of the characteristic quantity j of the growth direction of the electrical tree in the slice and the characteristic quantity k of the insulation quality problem of the cable body, observing whether the cable insulation has color abnormalities, if there are color abnormalities, slicing the cable section with color abnormalities; performing physical and chemical property tests on the cable sections with color abnormalities to test whether the insulation is degraded, if there is no insulation degradation, taking m=0, if there is insulation degradation, taking m=1.

[0022] Preferably, the corresponding relationship between the magnitude of the characteristic quantity for judging different fault types and the cable fault type is:

[0023] If 0≤V≤1.8, the cable fault type is A-surface discharge;

[0024] If 1.8<V≤4.8, the cable fault type is B-cable insulation mechanical damage;

[0025] If 4.8≤V≤8.0, the cable fault type is air gap discharge between the C-stress cone and the cable interface;

[0026] If 8.0<V≤11.5, the cable fault type is D-stress cone and cable interface overlap misalignment;

[0027] If 11.5<V≤11.7, the cable fault type is E-cable insulation degradation;

[0028] If V>11.7, the cable fault type is F-cable insulation quality problem.

[0029] In a second aspect, the present invention provides a dissection platform for a faulty cable terminal, which is used for dissecting the faulty cable in the aforementioned quantitative analysis method of the faulty cable terminal, and the dissection platform comprises: a bracket, a locking wheel, a support rod and a cable tray; the cable tray is arranged on opposite sides of the bracket, and is provided with a bracket for holding the faulty cable terminal; the centers of the brackets of the two cable trays are on the same horizontal line; the locking wheel is arranged on one side of the bracket, and there are three locking wheels, which are respectively located on the upper side, left side and right side of a cable tray; the support rod is a telescopic rod, the lower end of which is vertically fixedly connected to the bottom of the bracket, and the other end is between the two cable trays, and is provided with a support ring.

[0030] Preferably, the bracket includes: a first support frame, a second support frame and an extension frame; the first support frame and the second support frame are symmetrically arranged, the tops of the two are connected by a connecting rod, and the bottoms are connected by a first connecting seat; the extension frame is arranged on a side of the second support frame away from the first support frame, and the extension frame is used to extend the support for the tail of the cable; the bottom of the extension frame is connected to the bottom of the second support frame through a second connecting seat, and the second connecting seat is provided with a tool box for storing anatomical tools; cable trays are fixedly installed at the same height of the first support frame, the second support frame and the extension frame, and the centers of the brackets of the three cable trays are on the same horizontal line; two universal brake wheels are symmetrically arranged on both sides of the bottom of the first support frame, the second support frame and the extension frame.

[0031] Preferably, the cable tray comprises: a bracket, a roller, a bearing and a bolt; the bottom of the bracket is fixedly connected to the cross bar on the bracket, and two groups of steps are symmetrically arranged on the top of the bracket, each group of steps is gradually inclined downward from the outside to the inside, and the lowest table tops of the two groups of steps are connected, and a bracket for placing the faulty cable terminal is formed at the center of the top surface of the bracket; a notch for installing the roller is opened downward on the top of the bracket; the roller is rotatably installed at the corner of each step surface on the top of the bracket through a bearing, and the bearing and the step are fixedly connected by bolts.

[0032] Preferably, the locking wheel is installed on the bracket through a fixing rod, and both ends of the fixing rod are fixedly connected to the bracket; a moving rod is vertically installed at the center of the locking wheel, and the moving rod vertically passes through the fixing rod through a threaded connection, and a pressure block is provided at the end of the moving rod away from the locking wheel, and the pressure block is used to contact the surface of the cable terminal to apply a clamping force thereto.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention introduces the appearance characteristic quantity a of the top seal, the appearance characteristic quantity b of the tail seal, the internal moisture characteristic quantity c of the top seal, the internal moisture characteristic quantity d of the tail seal, the internal insulation shield scar characteristic quantity e of the metal sheath fracture, the stress cone lap misalignment characteristic quantity f, the breakdown channel characteristic quantity g, the cable insulation shield fracture treatment condition characteristic quantity h, the cable curvature determining cable curvature characteristic quantity i, the sliced ​​electric tree growth direction characteristic quantity j, the cable body insulation quality problem characteristic quantity k, the physical and chemical properties test result characteristic quantity m, these fault characteristic quantities, by observing the appearance of the faulty cable terminal and dissecting it, the above fault characteristic quantities can be obtained to form a fault characteristic vector; and then the fault characteristic vector and the correlation matrix are quantitatively analyzed to obtain the fault type judgment characteristic quantity. By establishing the correlation between the fault type judgment characteristic quantity and the cable fault type, the cable fault type can be obtained, which can reduce the difficulty of fault analysis and obtain the accurate fault cause, laying the foundation for further proposing prevention and rectification measures and reducing the cable failure rate, and effectively improving the reliability of the cable line.

[0034] In addition, the present invention provides a complete cable dissection process when obtaining the fault characteristic vector, and provides scientific and clear cable dissection steps for dissecting the faulty cable.

[0035] Furthermore, the present invention also provides a dissection platform for the faulty cable terminal. By providing a cable support and a retractable support rod, the faulty cable terminal can be in a straight line, thereby obtaining an ideal dissection posture, reducing the difficulty of dissection, improving the dissection efficiency, and facilitating the dissection, observation, and measurement of the cable terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a structural schematic diagram of the dissecting platform of the faulty cable terminal in the present invention;

[0037] Figure 2 The structure of the cable support in the present invention is shown in FIG. Figure 1 ;

[0038] Figure 3 The structure of the cable support in the present invention is shown in FIG. Figure 2 ;

[0039] Figure 4 It is a schematic diagram of the structure of the support rod in the present invention;

[0040] Figure 5 It is a schematic diagram of the dissection process of the faulty cable terminal in the present invention;

[0041] Figure 6 It is a schematic diagram of the process of dissecting the cable system in the present invention;

[0042] Figure 7 The method utilizes the quantitative analysis method of the faulty cable terminal in the present invention to obtain the fault characteristic quantity from the fault phenomenon and generate a mind map of the correlation matrix.

[0043] Reference numerals in the figures:

[0044] 1. Bracket; 2. Locking wheel; 3. Support rod; 301. Support ring; 4. Cable terminal; 5. Cable support; 501. Bracket; 502. Roller; 503. Bearing; 504. Bolt; 6. Cable fixing clamp; 7. Extension rod; 8. Tool box; 9. Universal brake wheel. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only embodiments of a part of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0046] like Figure 1 As shown, embodiment 1 of the present invention provides a dissection platform for a faulty cable terminal, comprising: a bracket 1, a locking wheel 2, a support rod 3, a cable terminal 4; a cable support 5, a cable fixing clamp 6, an extension rod 7, a tool box 8 and a universal brake wheel 9.

[0047] The bracket 1 includes: a first support frame, a second support frame and an extension frame. The first support frame and the second support frame are symmetrically arranged, the tops of the two are connected by a connecting rod, and the bottoms are connected by a first connecting seat. The extension frame is arranged on the side of the second support frame away from the first support frame, and the bottom of the extension frame is connected to the bottom of the second support frame through the second connecting seat. The extension frame is used to support the tail end of the cable when the cable cut length is long, preferably more than 2m, to avoid the lack of support at the tail end of the cable, so that it falls and injures people. Two universal brake wheels 9 are symmetrically arranged on both sides of the bottom of the first support frame, the second support frame and the extension frame. In a preferred but non-restrictive embodiment of the present invention, the first connecting seat and the second connecting seat can be combined into one connecting seat or two separate connecting seats.

[0048] The tool box 8 is placed on the top of the second connecting seat and is used to place cable dissection tools.

[0049] Cable holders 5 are fixedly installed at the same height of the first support frame, the second support frame and the extension frame, and the centers of the brackets of the three cable holders are on the same horizontal straight line, which are used to support the cables at different positions, so that the cable terminals remain straight and evenly stressed, making it easy to dissect and observe faulty cable terminals.

[0050] like Figure 2 , Figure 3 As shown, in a preferred but non-limiting embodiment of the present invention, the cable bracket 5 includes: a bracket 501, a roller 502, a bearing 503 and a bolt 504. The bottom of the bracket 501 is fixedly connected to the bracket 1, and two groups of steps are symmetrically arranged on the top of the bracket 501. Each group of steps is gradually inclined downward from the outside to the inside. The lowest table tops of the two groups of steps are connected, so that a bracket for placing a faulty cable terminal is formed at the center of the top surface of the bracket 501. A notch for installing the roller is opened downward at the top of the bracket 501. The roller 502 is rotatably installed at the corner of each step surface on the top of the bracket 501 through the bearing 503, and the bearing 503 is fixed to the step by a bolt 504, and the bolt 504 is preferably a stainless steel bolt.

[0051] The first support frame is provided with locking wheels 2 on the left, right and top sides corresponding to the cable tray 5, which are used to apply locking force to the cable terminal from the top, left and right sides of the cable terminal when the cable terminal is placed on the top of the cable tray 5, so as to fix the cable terminal.

[0052] In a preferred but non-limiting embodiment of the present invention, each locking wheel 2 is mounted on the first support frame via a fixing rod, and both ends of the fixing rod are fixedly connected to the first support frame. A moving rod is vertically mounted at the center of the locking wheel 2, and the moving rod vertically passes through the fixing rod via a threaded connection, and a pressing block is arranged at one end of the moving rod away from the locking wheel 2, and the pressing block is used to contact the surface of the cable terminal and apply a pressing force thereto.

[0053] like Figure 1 , Figure 4 As shown, the support rod 3 is vertically installed at the top center of the connecting seat between the first support frame and the second support frame. The support rod 3 is a telescopic rod, and one end of the support rod 3 is fixedly connected to the connecting seat, and the other end is provided with a support ring 301, which is used to support the middle of the cable terminal. The support ring 301 is a semicircular ring with an opening facing upward, and the center of the semicircular ring and the center of the cable support are located on the same horizontal straight line, so that the cable terminal is in a straight line, avoiding bending in the middle of the cable terminal, which affects the dissection and measurement.

[0054] When the faulty cable terminal is placed on the first support frame, the support rod and the second support frame, and the faulty cable terminal needs to be rotated, a cable fixing clamp 6 can be installed at one end of the faulty cable terminal close to the second support frame. The cable fixing clamp 6 is a clamp structure commonly used in the prior art for fixing cables. An extension rod 7 is provided on one side of the cable fixing clamp 6. The extension rod 7 is used to increase the force arm to facilitate the rotation of the faulty cable terminal.

[0055] like Figure 5 As shown, embodiment 2 of the present invention provides a quantitative analysis method for a faulty cable terminal, comprising the following steps:

[0056] Step S1, cutting off the cable terminal at a first distance below the lower edge of the heat shrink tube at the lower end of the faulty cable terminal.

[0057] In a preferred but non-limiting embodiment of the present invention, the first distance is 20-200 mm, which can avoid the inability to verify whether the stripping lengths of the cable outer sheath and metal sheath are correct, as well as the sealing condition of the terminal tail due to cutting too short.

[0058] Step S2, fixing the faulty cable terminal to be dissected on the dissecting platform of the faulty cable terminal in Embodiment 1. Step S2 specifically includes the following steps:

[0059] Step S2.1, place one end of the faulty cable terminal with the outlet fitting on the cable support 5 of the first support frame, the other end on the cable support 5 of the second support frame, and the middle part on the upper end support ring 301 of the support rod 3.

[0060] Step S2.2, align the top outlet fitting of the faulty cable terminal with the pressing block of the locking wheel 2 at a second distance above the upper edge of the crimping part of the cable core.

[0061] In a preferred but non-limiting embodiment of the present invention, the second distance is 5 mm-10 mm.

[0062] Step S2.3, rotate the faulty cable terminal so that the breakdown position faces upward, and lock the three locking wheels to fix the cable terminal.

[0063] Step S3, after fixing the faulty cable terminal on the dissection platform, observe the top seal and the tail seal of the cable terminal to determine whether there is misalignment between the cable terminal body and the cable.

[0064] Suppose the appearance characteristic of the top seal is a. If there is tearing, take a=1, if there is no tearing, take a=0; suppose the appearance characteristic of the tail seal is b. If the terminal tail is separated from the seal or the seal has bulging, take b=1, if the terminal tail is not separated from the seal and the seal has no bulging, take b=0.

[0065] Step S4, dissecting the cable terminal in a room with a room temperature not lower than 20°C, to ensure that the terminal body and the cable are not too hard to be dissected, and to avoid contamination of the inside of the cable terminal body and the cable body after dissection caused by bad weather outdoors. Figure 6 As shown, step S4 specifically includes the following steps:

[0066] Step S4.1, remove the top seal and the tail seal of the terminal cable.

[0067] Specifically, loosen the three-side locking wheels, rotate the cable terminal 90°, make the fault breakdown position face the left or right side, and lock the three-side locking wheels. Remove the collector ring at the tail of the cable terminal, and peel off the seals at the top and tail, and observe and obtain the following characteristic quantities:

[0068] ① Observe whether there are any signs of moisture inside. Let the moisture characteristic of the top seal be c. If there are signs of moisture, take c=1; if there are no signs of moisture, take c=0. Let the moisture characteristic of the tail seal be d. If there are signs of moisture, take d=1; if there are no signs of moisture, take d=0.

[0069] ② Check whether the internal insulation shield of the metal sheath of the cable body is scratched by knife marks or punctured by the burrs of the metal sheath. Suppose the characteristic quantity of the internal insulation shield of the metal sheath break is e. If the internal insulation shield of the metal sheath break is scratched by the burrs of the metal sheath or has knife marks, take e=1; if the internal insulation shield of the metal sheath break has neither knife marks nor puncture marks of the metal sheath burrs, take e=0.

[0070] Step S4.2: Cut the cable terminal body from the top to the tail perpendicular to the cable in a straight line, taking care not to scratch the internal cable body.

[0071] Measure the overlap depth between the cable insulation shield and the semi-conductive part of the stress cone inside the terminal, that is, the distance L between the cable insulation shield break and the lower edge of the semi-conductive buffer section inside the stress coned .

[0072] Furthermore, if the fault causes the cable insulation shielding fracture to be blurred, you can use a piece of glass to gently scrape the nearby cable body. If white is leaking out, it proves that this position is the cable insulation. If black is leaking out, it proves that this position is the insulation shielding layer. If the fault causes the cable insulation shielding fracture to be incomplete, this step does not measure the overlap depth L between the cable insulation shielding and the semi-conductive part of the terminal internal stress cone. d , mark the lower edge of the semi-conductive buffer section inside the stress cone on the cable insulation shield with a white marker pen, and measure the distance from the marked position to the cable insulation shield in the subsequent steps as the overlap depth L d If conditions permit, try to complete the overlap depth measurement in this step, because measuring after marking may increase the measurement error.

[0073] Step S4.3, rotate the terminal 180°, and again cut the cable terminal body from the top to the tail perpendicular to the cable along a straight line, being careful not to scratch the internal cable body, and then mark the lower edge of the semi-conductive buffer section inside the stress cone on the cable insulation shielding layer in the cut with a white marker. At this point, the entire cable terminal body has been divided into two halves.

[0074] If the overlap depth cannot be measured in step S4.2, then continue to measure the overlap depth in this step. The specific method is: remove the two halves of the terminal body. If the cable insulation shield is broken, determine the break position based on the mark formed by the insulation shield on the insulation layer and the highest point around the break. Measure the lower edge of the semi-conductive buffer section inside the stress cone marked from the break to the previously marked stress cone as the overlap depth L between the cable insulation shield and the semi-conductive part of the stress cone inside the terminal. d If the fracture is below the lower edge of the semi-conductive buffer section inside the stress cone marked previously, record L d is negative, measure the length L of the semi-conductive buffer section inside the stress cone s , assuming that the stress cone lap misalignment characteristic quantity is f, if L d ≤0 or L d ≥L s -5mm, then the stress cone lap misalignment characteristic f takes 1, if 0 <L d <L s -5mm, the stress cone lap misalignment characteristic quantity f is 0.

[0075] Step S4.4: Check the cable body. Figure 3 As shown, step S4.4 specifically includes the following steps:

[0076] Step S4.4.1, check whether there is a surface discharge channel from the insulation shielding break to the top core or a radial breakdown hole on the cable body, and the distance between the center of the breakdown hole and the insulation shielding break of the cable.

[0077] Assume that the characteristic quantity of the breakdown channel is g. If there is a surface discharge channel from the insulation shielding fracture to the top core, g = 0; if there is a radial breakdown hole, it is divided into the following three cases: if the breakdown hole is located at the metal sheath fracture, g = 1; if the center of the breakdown hole is at the insulation shielding fracture, g = 4; if the center of the breakdown hole is between the insulation shielding fracture and the upper edge of the semi-conductive buffer section inside the stress cone, g = 3. If the breakdown hole is located at a position other than the above-mentioned position, and the insulation at the breakdown position has obvious color abnormalities or impurities, g = 6.

[0078] Step S4.4.2, check whether the cable insulation shielding fracture has a smooth transition, and whether there are pits, burrs, or steps. Suppose the characteristic quantity of the cable insulation shielding fracture processing condition is h. If there are no pits, burrs, or steps, take h=0; if there are pits, burrs, or steps, take h=1.

[0079] Step S4.4.3, measure the cable curvature. The cable terminal may bend the terminal body and the end of the cable body inside it due to problems with the fixing method, and the end is roughly in a straight line. Remove the cable body from the dissection platform and place it on a clean plane. Use a long ruler with a 1000mm scale to align the cable end (the end without the wire fittings crimped) from the outside of the cable bend, and place the ruler close to the cable end. Use a short ruler to overlap the 0 scale line of the long ruler and measure the distance h from the ruler to the cable at the 0 scale line. Cable curvature. The characteristic quantity i of the cable curvature is, when θ<30°, i=0; when θ≥30°, i=1.

[0080] Step S5, local dissection.

[0081] Use a cable stripping cutter to strip the cable axially within the third distance on both sides of the breakdown position to form a 1mm thick slice to observe whether there are radial electrical branches and the growth direction of the electrical branches. Among them, the third distance is less than or equal to 100mm. Let the characteristic quantity of the electrical tree growth direction of the slice be j. If the electrical tree grows from the outside to the inside, take j=-1; if the electrical tree grows from the inside to the outside, take j=1; if there is no electrical tree, take j=0.

[0082] Observe whether there are impurities or micropores, and the characteristic quantity k of the cable body insulation quality problem. If there are no impurities and micropores, take k=0; if there are impurities or micropores, take k=1.

[0083] Step S6, sample extraction.

[0084] If the cable insulation color is found to be abnormal, cut the cable into slices for the abnormal color section.

[0085] S1-S6 full video recording.

[0086] Step S7, test detection.

[0087] The cable slice obtained in step S6 is subjected to a physical and chemical property test to test whether the insulation is aged. Assume that the characteristic quantity of the physical and chemical property test result is m, if there is no insulation degradation, m=0, if there is insulation degradation, m=1.

[0088] Step S8, fault cause determination, specifically including the following steps:

[0089] Step S8.1, calculate the fault type judgment feature quantity V = |nP|, n is the fault feature vector, the mind map is as follows Figure 7 As shown, P is the correlation matrix, n = [abcdefghijkm],

[0090]

[0091] Step S8.2, establish a corresponding table between the fault type judgment characteristic quantity and the cable fault type, as shown in Table 1 below; among them, the common causes of cable terminal failure are divided into: A-surface discharge, B-cable insulation mechanical damage, C-stress cone and cable interface air gap discharge, D-stress cone and cable interface overlap misalignment, E-cable insulation degradation, F-cable insulation quality problems.

[0092] Table 1. Correspondence between fault type judgment characteristic quantity and cable fault type

[0093] Diagnosis Fault type 0≤V≤1.8 A 1.8＜V≤4.8 B 4.8≤V≤8.0 C 8.0＜V≤11.5 D 11.5＜V≤11.7 E V＞11.7 F

[0094] Step S8.3: Determine the characteristic quantity according to the calculated fault type, and obtain the cable fault type by looking up Table 1.

[0095] The beneficial effect of the present invention is that, compared with the prior art, the present invention introduces the appearance characteristic quantity a of the top seal, the appearance characteristic quantity b of the tail seal, the internal moisture characteristic quantity c of the top seal, the internal moisture characteristic quantity d of the tail seal, the internal insulation shield scar characteristic quantity e of the metal sheath fracture, the stress cone lap misalignment characteristic quantity f, the breakdown channel characteristic quantity g, the cable insulation shield fracture treatment condition characteristic quantity h, the cable curvature determining cable curvature characteristic quantity i, the sliced ​​electric tree growth direction characteristic quantity j, the cable body insulation quality problem characteristic quantity k, the physical and chemical properties test result characteristic quantity m, these fault characteristic quantities, by observing the appearance of the faulty cable terminal and dissecting it, the above fault characteristic quantities can be obtained to form a fault characteristic vector; and then the fault characteristic vector and the correlation matrix are quantitatively analyzed to obtain the fault type judgment characteristic quantity. By establishing the correlation between the fault type judgment characteristic quantity and the cable fault type, the cable fault type can be obtained, which can reduce the difficulty of fault analysis, obtain the accurate fault cause, and lay the foundation for further proposing prevention and rectification measures and reducing the cable failure rate, and effectively improve the reliability of the cable line.

[0096] In addition, the present invention provides a complete cable dissection process when obtaining the fault characteristic vector, and provides scientific and clear cable dissection steps for dissecting the faulty cable.

[0097] Furthermore, the present invention also provides a dissection platform for the faulty cable terminal. By providing a cable support and a retractable support rod, the faulty cable terminal can be in a straight line, thereby obtaining an ideal dissection posture, reducing the difficulty of dissection, improving the dissection efficiency, and facilitating the dissection, observation, and measurement of the cable terminal.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A quantitative analysis method for faulty cable terminals, characterized in that: The following steps are involved: Place the faulty cable terminal on the dissection platform; Observe the appearance of the faulty cable terminal and dissect it to determine the top seal appearance feature a, the tail seal appearance feature b, the top seal internal moisture feature c, the tail seal internal moisture feature d, the metal sheath fracture internal insulation shield scar feature e, the stress cone overlap misalignment feature f, the breakdown channel feature g, the cable insulation shield fracture treatment feature h, the cable curvature feature i, the slice electrical tree growth direction feature j, the cable body insulation quality problem feature k, and the physical and chemical properties test result feature m; Calculate the fault type judgment feature V = |nP|; where n = [a bc defghijkm], Establish the corresponding relationship between the size of the characteristic quantity for judging different fault types and the cable fault type as the basis for judging the fault type; The size of the characteristic quantity is judged according to the obtained fault type, and the cable fault type is determined.

2. The quantitative analysis method of a faulty cable terminal according to claim 1, characterized in that: Placing the faulty cable terminal on the dissection platform comprises the following steps: Cutting the cable terminal at a first distance below the lower edge of the heat shrink tubing at the lower end of the faulty cable terminal; The two ends of the cut cable terminal are respectively placed on two cable holders (5) of the dissection platform, and the end of the cable terminal with the outlet fitting is placed on the cable holder (5) with the locking wheel (2); Align the outlet fitting with the second distance above the upper edge of the cable core crimping position with the clamping block of the locking wheel (2); Rotate the faulty cable terminal so that the breakdown position faces upwards, and lock the locking wheel (2).

3. The quantitative analysis method of a faulty cable terminal according to claim 2, characterized in that: The first distance is 20-200 mm; the second distance is 5 mm-10 mm.

4. The quantitative analysis method of a faulty cable terminal according to claim 1, characterized in that: Determining the values ​​of the top seal appearance feature quantity a and the tail seal appearance feature quantity b comprises the following steps: After fixing the faulty cable terminal on the dissecting platform, observe the top seal and tail seal of the cable terminal; If the top seal is torn, take a=1, if not, take a=0; If the terminal tail is separated from the tail seal or the tail seal has a bulging phenomenon, b=1 is taken; if the terminal tail is not separated from the tail seal and the tail seal has no bulging phenomenon, b=0 is taken.

5. The quantitative analysis method of a faulty cable terminal according to claim 4, characterized in that: Determining the values ​​of the moisture characteristic quantity c inside the top seal, the moisture characteristic quantity d inside the tail seal, and the insulation shielding scar characteristic quantity e inside the metal sheath fracture includes the following steps: After determining the values ​​of the top seal appearance characteristic quantity a and the tail seal appearance characteristic quantity b, rotate the cable terminal 90° so that the fault breakdown position faces the left or right side, and re-lock the faulty cable terminal; Remove the top seal and the tail seal, and check whether there are any signs of moisture inside the top seal and the tail seal; If there is moisture inside the top seal, take c = 1, otherwise, take c = 0; if there is moisture inside the tail seal, take d = 1, otherwise, take d = 0; Check whether the insulation shield inside the broken end of the cable body metal sheath has any scratches from knife or puncture marks from the burrs of the metal sheath. If the insulation shield inside the broken end of the metal sheath has any scratches from puncture marks from the burrs of the metal sheath or knife marks, take e=1; otherwise, take e=0.

6. The quantitative analysis method of a faulty cable terminal according to claim 5, characterized in that: Determining the value of the stress cone lap misalignment characteristic quantity f includes the following steps: After determining the values ​​of the internal moisture characteristic quantity c of the top seal, the internal moisture characteristic quantity d of the tail seal, and the internal insulation shielding scar characteristic quantity e of the metal sheath fracture, the cable terminal body is cut open along a straight line perpendicular to the cable from the top to the tail, and the overlap depth L between the cable insulation shield and the semi-conductive part of the internal stress cone of the terminal is measured for the first time. d ; Rotate the cable terminal 180°, cut the cable terminal body from the top to the tail perpendicular to the cable in a straight line again, remove the two parts of the cable terminal to expose the cable body; if the first measurement cannot obtain L d , then the second measurement L d ; Measure the length L of the semi-conductive buffer section inside the stress cone s ; If L d ≤0 or L d ≥Ls-5mm, then f is 1, if 0 <L d <L s -5mm, then f is 0.

7. The quantitative analysis method of a faulty cable terminal according to claim 6, characterized in that: Determining the value of the breakdown channel characteristic quantity g comprises the following steps: After determining the value of the stress cone overlap misalignment characteristic quantity f, check whether there is a surface discharge channel from the insulation shielding break to the top core on the cable body or a radial breakdown hole, and the distance between the center of the breakdown hole and the cable insulation shielding break; If there is a surface discharge channel from the insulation shielding break to the top wire core, take g=0; if there is a radial breakdown hole, it is divided into the following three cases: if the breakdown hole is located at the metal sheath break, take g=1; if the center of the breakdown hole is at the insulation shielding break, take g=4; if the center of the breakdown hole is between the insulation shielding break and the upper edge of the semi-conductive buffer section inside the stress cone, take g=3; if the breakdown hole is located at a position other than the above-mentioned position, and the insulation at the breakdown position has obvious color abnormalities or impurities, take g=6.

8. The quantitative analysis method of a faulty cable terminal according to claim 6, characterized in that: Determining the value of the characteristic quantity h of the cable insulation shielding fracture treatment condition includes the following steps: After determining the value of the stress cone overlap misalignment characteristic quantity f, check whether there are pits, burrs, and steps on the cable insulation shielding fracture; If there are no pits, burrs or steps, take h = 0; otherwise, take h = 1.

9. The quantitative analysis method of a faulty cable terminal according to claim 6, characterized in that: Determining the cable curvature The value of the cable curvature characteristic quantity i is determined, comprising the following steps: After determining the value of the stress cone overlap misalignment characteristic quantity f, measure the cable bending θ; When θ<30°, i=0; when θ≥30°, i=1.

10. The quantitative analysis method of a faulty cable terminal according to any one of claims 7 to 9, characterized in that: The method of determining the values ​​of the characteristic quantity j of the growth direction of the electrical tree in the slice and the characteristic quantity k of the insulation quality problem of the cable body comprises the following steps: Use a cable stripping cutter to cut the cable axially within the third distance range on both sides of the breakdown position to obtain cable slices, wherein the third distance is less than or equal to 100 mm; Observe whether there are radial electrical branches in the cable slice and the direction of the electrical branches. If the electrical branches grow from the outside to the inside, take j = -1; if the electrical branches grow from the inside to the outside, take j = 1; if there are no electrical branches, take j = 0; Observe the cable slices for impurities or micropores. If there are no impurities or micropores, take k=0; if there are impurities or micropores, take k=1.

11. The quantitative analysis method of a faulty cable terminal according to claim 10, characterized in that: Determining the value of the characteristic quantity m of the physical and chemical property test result includes the following steps: After determining the values ​​of the characteristic quantity j of the electrical tree growth direction of the slice and the characteristic quantity k of the cable body insulation quality problem, observe whether the cable insulation has color abnormalities. If there are color abnormalities, slice the cable section with abnormal color; Conduct physical and chemical property tests on cable slices with abnormal color to test whether the insulation is degraded. If there is no insulation degradation, take m=0; if there is insulation degradation, take m=1.

12. The quantitative analysis method of a faulty cable terminal according to any one of claims 1 to 11, characterized in that: The corresponding relationship between the size of the characteristic quantity for judging different fault types and the cable fault type is as follows: If 0≤V≤1.8, the cable fault type is A-surface discharge; If 1.8<V≤4.8, the cable fault type is B-cable insulation mechanical damage; If 4.8≤V≤8.0, the cable fault type is air gap discharge between the C-stress cone and the cable interface; If 8.0<V≤11.5, the cable fault type is D-stress cone and cable interface overlap misalignment; If 11.5<V≤11.7, the cable fault type is E-cable insulation degradation; If V>11.7, the cable fault type is F-cable insulation quality problem.

13. A dissection platform for a faulty cable terminal, used for dissecting a faulty cable in the quantitative analysis method for a faulty cable terminal according to any one of claims 1 to 12, characterized in that: The dissection platform comprises: a support (1), a locking wheel (2), a support rod (3) and a cable support (5); The cable trays (5) are arranged on opposite sides of the bracket (1), and are provided with brackets for holding faulty cable terminals; the centers of the brackets of the two cable trays (5) are on the same horizontal line; The locking wheel (2) is arranged on one side of the bracket (1), and three locking wheels (2) are arranged, which are respectively located on the upper side, left side and right side of a cable tray (5); The support rod (3) is a telescopic rod, the lower end of which is vertically fixedly connected to the bottom of the bracket (1), and the other end of which is located between the two cable supports (5) and is provided with a support ring (301).

14. The dissection platform for the faulty cable terminal according to claim 13, characterized in that: The support (1) comprises: a first support frame, a second support frame and an extension frame; The first support frame and the second support frame are symmetrically arranged, and the tops of the two are connected by a connecting rod, and the bottoms are connected by a first connecting seat; The extension frame is arranged on a side of the second support frame away from the first support frame, and is used to extend and support the tail of the cable; the bottom of the extension frame is connected to the bottom of the second support frame via a second connecting seat, and the second connecting seat is provided with a tool box (8) for storing dissecting tools; The first support frame, the second support frame and the extension frame are all fixedly mounted with cable brackets 5 at the same height, and the bracket centers of the three cable brackets are on the same horizontal line; Two universal brake wheels (9) are symmetrically arranged on both sides of the bottom of the first support frame, the second support frame and the extension frame.

15. The dissection platform for the faulty cable terminal according to claim 13, characterized in that: The cable support (5) comprises: a support (501), a roller (502), a bearing (503) and a bolt (504); The bottom of the bracket (501) is fixedly connected to the crossbar on the support (1), and two groups of steps are symmetrically arranged on the top of the bracket (501), each group of steps is gradually inclined downward from the outside to the inside, and the lowest surfaces of the two groups of steps are connected, forming a bracket for placing the faulty cable terminal at the center of the top surface of the bracket (501); A notch for installing a roller (502) is provided downwardly at the top of the bracket (501); the roller (502) is rotatably installed at the corner of each step surface at the top of the bracket (501) through a bearing (503), and the bearing (503) and the step are fixedly connected by a bolt (504).

16. The dissection platform for the faulty cable terminal according to claim 13, characterized in that: The locking wheel (2) is mounted on the bracket (1) via a fixing rod, and both ends of the fixing rod are fixedly connected to the bracket (1); a moving rod is vertically mounted at the center of the locking wheel (2), and the moving rod vertically passes through the fixing rod via a threaded connection; a pressure block is provided at one end of the moving rod away from the locking wheel (2), and the pressure block is used to contact the surface of the cable terminal to apply a pressing force thereto.

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