A shielding device for DC leakage current test of a lightning arrester

Abstract

The application relates to the field of high-voltage tests of lightning arresters, in particular to a shielding device for a direct-current leakage current test of a lightning arrester, which comprises a lightning arrester and a detection shielding mechanism, wherein the detection shielding mechanism comprises a connecting post and a measuring layer, the outer side of the measuring layer is attached with a first insulating layer, and the side, away from the measuring layer, of the first insulating layer is attached with a shielding layer. The device can be flexibly bent, is compatible with lightning arrester tests of different diameters, and the shielding film and the measuring layer form a capacitor, both of which are at the same potential as the ground, have no voltage difference, and cannot generate a capacitor charging current, so that the capacitor charging current can be shielded; there are charged particles between the shielding film and the measuring layer, both of which are at the same potential as the ground, have no voltage difference, the charged particles cannot move in a certain direction, and cannot form a space stray current, so that the space stray current can be shielded; the lightning arrester grading cover does not need to be removed during the test process, and the problem that an interference current affects the accuracy of the lightning arrester test is effectively solved.

Description

Technical Field

[0001] This invention relates to the field of high-voltage testing of surge arresters, and in particular to a shielding device for testing DC leakage current of surge arresters. Background Technology

[0002] According to GB 50150 "Standard for Acceptance Testing of Electrical Equipment in Electrical Installation Engineering" and DL / T 596 "Preventive Testing Procedures for Power Equipment", the DC leakage current test of surge arresters is one of the items that need to be carried out in the acceptance test and preventive test. According to the requirements of the procedure, a specified DC voltage is applied to the upper and lower ends of each surge arrester, and the leakage current is considered qualified if it does not exceed 50μA. When carrying out this test, it is often encountered that the equalizing cover of the upper surge arrester is large and close to the lower flange of the upper section. Stray current, capacitor charging current and surface leakage current will cause the DC leakage current value to be large, or even exceed the value required by the procedure. In existing technologies, two shielding methods are commonly used: one is to use a bare conductor to wrap around the nearest skirt above the flange and connect it to the voltage-pressurizing wire shielding layer; the other is to remove the equalizing cover. However, bare conductor shielding can only shield the surface current of the surge arrester. Stray currents and capacitor charging currents in the space will still affect the test results. Removing the equalizing cover is a large-scale project, and the equalizing cover needs to be reinstalled after the test. The removal and installation processes involve working at height and lifting, which not only increases the operating cost but also increases the safety risks.

[0003] Based on the above, this invention proposes a shielding device for testing DC leakage current of surge arresters. The shielding device can detect stray current, capacitor charging current, and leakage current on the surface of the surge arrester during the test, making the test results more accurate than the traditional bare conductor shielding method, and more economical and safer than removing the equalizing cover. Summary of the Invention

[0004] In view of the problems in the above-mentioned or existing technologies, such as the use of traditional bare wires to wrap around the surge arrester and the removal of the equalizing cover in the DC leakage current test of surge arresters, which cannot effectively avoid the influence of interference current on the test accuracy, and the poor economy and high safety risks of removing the equalizing cover, this invention is proposed.

[0005] Therefore, the purpose of this invention is to provide a shielding device for testing the DC leakage current of a surge arrester.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a shielding device for testing the DC leakage current of a surge arrester, comprising a surge arrester and a detection shielding mechanism, which includes a terminal block and a measuring layer. A first insulating layer is attached to the outer side of the measuring layer, and a shielding layer is attached to the side of the first insulating layer away from the measuring layer. A second insulating layer is attached to the side of the shielding layer away from the first insulating layer. The terminal block includes an inner terminal block, an outer terminal block is sleeved on the inner terminal block, and an insulating filler is filled between the inner and outer terminal blocks. The detection shielding mechanism encloses the surge arrester, and the measuring layer contacts the end flange of the surge arrester. The shielding layer contacts the shed of the surge arrester. The inner terminal block is connected to the measuring layer, and the outer terminal block is connected to the shielding layer. A connection and fixing mechanism includes a first strap and a second strap respectively connected to both ends of the second insulation layer. The other end of the first strap is connected to a buckle seat, and a buckle cover is provided on one side of the buckle seat. The end of the second strap is clamped between the buckle seat and the buckle cover. Ribs are provided on both sides of the second strap, and the ribs on both sides of the second strap are staggered. The buckle seat and the buckle cover are provided with matching ribs with slots. The buckle cover has a first groove and a second groove on the side away from the buckle seat. A slider is sleeved in the first groove. The slider is arranged in a right-angled triangle, and the bottom of the first groove slides in contact with the inclined surface of the slider. A screw connects the slider, the buckle cover, and the buckle seat. A spring is sleeved in the second groove, and a screw connects the spring, the buckle cover, and the buckle seat.

[0007] As a preferred embodiment of the shielding device for testing DC leakage current of surge arresters according to the present invention, wherein: the measuring layer is made of a rectangular metal film, and the first insulating layer is made of a rectangular insulating film, the length and width of the first insulating layer are both 1.1 times that of the measuring layer, and the measuring layer is bonded to the first insulating layer.

[0008] As a preferred embodiment of the shielding device for DC leakage current testing of surge arresters according to the present invention, the shielding layer is made of a flexible metal film, and the shielding layer includes two parallel shielding strips, a shielding film is disposed between the shielding strips, and a connecting strip connects the shielding film and the shielding strips.

[0009] As a preferred embodiment of the shielding device for DC leakage current testing of surge arresters according to the present invention, wherein: the shielding film in the shielding layer is superimposed and bonded to the first insulating layer, and the length and width of the shielding film are both greater than the first insulating layer, and the shielding strip of the shielding layer is in contact with the surge arrester skirt.

[0010] As a preferred embodiment of the shielding device for testing DC leakage current of the surge arrester of the present invention, the second insulating layer is made of rubber and insulating fiber composite material.

[0011] As a preferred embodiment of the shielding device for testing DC leakage current of surge arresters according to the present invention, wherein: the density of the slot is greater than the density of the ribs, and the end of the screw is fastened to the fastener.

[0012] As a preferred embodiment of the shielding device for DC leakage current testing of surge arresters according to the present invention, wherein: the second strap passes through the short straight side of the slider between the buckle seat and the buckle cover, and the second strap passes through the slot along the long straight side of the slider.

[0013] As a preferred embodiment of the shielding device for testing DC leakage current of the surge arrester according to the present invention, wherein: the length of the inner wall of the inclined side of the first slide groove is greater than the length of the inclined side of the slider.

[0014] As a preferred embodiment of the shielding device for testing DC leakage current of surge arresters according to the present invention, wherein: a third groove is provided at the bottom of the second groove, and the screw in the second groove is slidably connected to the third groove.

[0015] As a preferred embodiment of the shielding device for testing DC leakage current of the surge arrester of the present invention, the first slide groove and the second slide groove are symmetrically distributed about both sides of the slot.

[0016] The beneficial effects of the shielding device for DC leakage current testing of surge arresters of the present invention are as follows: The device can be flexibly bent, is compatible with surge arresters of different diameters for testing, and the shielding film and the measuring layer form a capacitor. Both are at the same potential as the ground, have no voltage difference, and will not generate capacitor charging current, thus achieving shielding of capacitor charging current. There are charged particles between the shielding film and the measuring layer. Both are at the same potential as the ground, have no voltage difference, and the charged particles will not move in a directional manner, thus not forming stray current in space, thus achieving shielding of stray current in space. The testing process does not require the removal of the surge arrester equalization cover, effectively solving the problem of interference current affecting the accuracy of surge arrester testing. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the shielding device used for DC leakage current testing of surge arresters and its assembly structure with the surge arrester.

[0019] Figure 2 This is a schematic diagram of the test mechanism in the sleeved state of the shielding device used for testing the DC leakage current of a surge arrester.

[0020] Figure 3Shielding device for DC leakage current testing of surge arresters Figure 2 The structural cross-sectional view of A in the middle.

[0021] Figure 4 This is a schematic diagram of the structure of the test mechanism after the shielding device for testing the DC leakage current of a surge arrester has been deployed.

[0022] Figure 5 The equivalent circuit diagram of the charging current of the shielding capacitor in the test mechanism of the shielding device used for DC leakage current testing of surge arresters.

[0023] Figure 6 The equivalent loop diagram of stray current in the shielded space of the test mechanism for the shielded device used in the DC leakage current test of surge arresters.

[0024] Figure 7 This is a schematic diagram of the fixing mechanism of the shielding device used for DC leakage current testing of surge arresters.

[0025] Figure 8 Shielding device for DC leakage current testing of surge arresters Figure 7 A structural diagram from the rear view.

[0026] Figure 9 This is a structural cross-sectional view of the fixing mechanism of the shielding device used for DC leakage current testing of surge arresters.

[0027] Figure 10 Shielding device for DC leakage current testing of surge arresters Figure 9 Structural decomposition diagram Detailed Implementation

[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0029] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0030] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0031] Example 1, referring to Figures 1 to 7This is the first embodiment of the present invention. This embodiment provides a surface leakage current testing device for DC leakage testing of a surge arrester 300. It can effectively avoid the interference of capacitor charging current and surface leakage current in the DC leakage test of the surge arrester 300 with the accuracy of the test results. It includes a surge arrester 300 and a detection shielding mechanism 100, which includes a terminal block 105 and a measuring layer 101. A first insulating layer 102 is attached to the outer side of the measuring layer 101, and a shielding layer 103 is attached to the side of the first insulating layer 102 away from the measuring layer 101. A second insulating layer 104 is attached to the side away from the first insulating layer 102. The terminal block 105 includes an inner wiring layer 105a, an outer wiring layer 105c is sleeved on the inner wiring layer 105a, and an insulating filler 105b is filled between the inner wiring layer 105a and the outer wiring layer 105c. The detection shielding mechanism 100 covers the surge arrester 300, and the measuring layer 101 contacts the end flange of the surge arrester 300. The shielding layer 103 contacts the skirt of the surge arrester 300. The inner wiring layer 105a is connected to the measuring layer 101, and the outer wiring layer 105c is connected to the shielding layer 103.

[0032] Specifically, the measuring layer 101 is made of a rectangular metal film, and the first insulating layer 102 is also made of a rectangular insulating film. The length and width of the first insulating layer 102 are both 1.1 times that of the measuring layer 101. The measuring layer 101 and the first insulating layer 102 are bonded together. The shielding layer 103 is made of a flexible metal film and includes two parallel shielding strips 103a. A shielding film 103b is disposed between the shielding strips 103a, and a connecting strip 103c connects the shielding film 103b and the shielding strips 103a. The shielding film 103b in the shielding layer 103 is superimposed and bonded to the first insulating layer 102, and the length and width of the shielding film 103b are both greater than those of the first insulating layer 102. The shielding strips 103a of the shielding layer 103 are in contact with the skirt of the surge arrester 300. The second insulating layer 104 is made of a rubber and insulating fiber composite material.

[0033] The working principle and advantages of this device are further explained by combining actual DC leakage tests on surge arrester 300: During DC leakage current testing, a DC voltage as required by regulations is applied between the upper and lower flanges of surge arrester 300. Under this voltage, in addition to generating the target current flowing through the internal valve plates of surge arrester 300, three types of interference currents are also generated: 1. Surface leakage current flowing through the surface of surge arrester 300; 2. Stray current generated by the directional movement of space charges under the influence of the electric field; 3. Equalizing cover (attached) Figure 1The annular cage at the top of the surge arrester 300 and the flange form a capacitor, which generates a capacitor charging current under DC voltage. The measuring wire used in the DC leakage current test consists of a core wire, a first insulation layer 102, a shielding layer 103, and a second insulation layer 104. The core wire is connected to the ammeter, and the current flowing through it is the test reading. The first insulation layer 102 is used to separate the core wire from the shielding layer 103, preventing the current in the shielding layer 103 from flowing into the core wire and interfering with the test reading. The shielding layer 103 is directly grounded and isolated from the ammeter. The second insulation layer 104 is the inner three-layer protection, which avoids wear and damage to the measuring wire during use and also prevents the test personnel from being injured by residual charge due to direct contact with the shielding layer 103. Using a shielding ring allows the surface current of the surge arrester 300 to flow into the ground through the shielding ring and the shielding layer 103, so that it does not affect the measurement reading. However, stray current and capacitor charging current will still flow through the core wire and the ammeter, causing the test data to be too high.

[0034] First, a DC leakage current test of the surge arrester 300 is required, which necessitates the cooperation of existing equipment such as a DC high-voltage generator, voltage application lines, test leads, and ammeters. The shielding mechanism 100 is used to detect the influence of surface current, stray current, and capacitor charging current of the surge arrester 300 during the shielding test. (Refer to...) Figure 1 and Figure 4 The assembly method of the shielding mechanism 100 and the surge arrester 300 is tested. A DC high-voltage generator generates an adjustable voltage to ground, which is applied to the upper flange and equalizing cover of the surge arrester 300 through the voltage line. Under the action of this voltage, in addition to the measured current I flowing through the valve plate inside the surge arrester 300, three kinds of interference currents are generated at the same time: the surface current flowing through the surface of the surge arrester 300, the stray current in space, and the capacitor charging current. The test wire is connected to the ammeter, and the current flowing through it is the test measurement value. The shielding wire is directly grounded, and the current flowing through it is directly conducted to the ground and will not become part of the measurement value.

[0035] When the shielding device is in use, the measuring layer 101 is in close contact with the lower flange of the upper section and the upper flange of the middle section of the surge arrester 300, and is connected to the core wire of the measuring line through the terminal block 105. The measured current flowing through the valve plate inside the surge arrester 300 becomes the test measurement value through the measuring layer 101, the lower flange of the upper section, the inner wiring layer 105a of the terminal block 105, the core wire of the test line and the ammeter.

[0036] The shielding strip 103a of the shielding layer 103 is tightly attached to the skirts on both sides of the upper and lower flanges of the surge arrester 300. The surface current of the surge arrester 300 flows into the ground through the shielding strip 103a, the outer wiring layer 105c of the terminal block 105, and the shielding wire of the test line matched with the test equipment, without passing through the measuring ammeter, thereby achieving the shielding of the leakage current on the surface of the surge arrester 300.

[0037] The equivalent circuit diagram for shielding the charging current of the capacitor is as follows: Figure 5 As shown, the equalizing shield and the shielding film 103b form a capacitor. Under the action of the DC voltage applied by the DC high voltage generator, a capacitor charging current will be generated. The current loop is: positive terminal of DC high voltage generator, ground, shielding wire of test line, outer wiring layer 105c of terminal 105, shielding film 103b of shielding device, equalizing shield, voltage line, negative terminal of DC high voltage generator. It does not flow through the ammeter, so it will not affect the test measurement value. The shielding film 103b and the measuring layer 101 also form a capacitor, but both are at the same potential as the ground and there is no voltage difference. Therefore, no capacitor charging current will be generated. Thus, the capacitor charging current can be shielded.

[0038] The equivalent circuit diagram for shielding stray currents is as follows: Figure 6 As shown, stray current in space is formed by the directional movement of charged particles in the atmosphere between the equalizing shield and the shielding film 103b under the action of a DC electric field. This electric field is generated by the voltage applied between the equalizing shield and the shielding film 103b by the DC high voltage generator. The direction of movement of charged particles is as follows: positively charged particles move towards the equalizing shield, and negatively charged particles move towards the shielding film 103b. The current loop of the stray current in space is: positive terminal of the DC high voltage generator, ground, shielding wire of the test line, outer wiring layer 105c of terminal 105, shielding film 103b of the shielding device, air between the shielding film 103b and the equalizing shield, equalizing shield, pressurizing wire, negative terminal of the DC high voltage generator. It does not flow through the ammeter, so it will not affect the test measurement value. There are also charged particles between the shielding film 103b and the measuring layer 101, but both are at the same potential as the ground and there is no voltage difference. The charged particles will not move in a directional manner and will not form stray current in space. Thus, the shielding of stray current in space can be achieved.

[0039] In summary, this device can effectively ensure the accuracy of the DC leakage test results of surge arrester 300, and eliminates the need to disassemble the equalizing cover of surge arrester 300.

[0040] Example 2, refer to Figure 1 and Figures 7-10This is the second embodiment of the present invention. Unlike the previous embodiment, this embodiment provides a fixing mechanism for the surface leakage current testing device for DC leakage testing of the surge arrester 300. This achieves a reliable connection between the flexible, sheet-like detection shielding mechanism 100 and the surge arrester 300. The fixing mechanism includes a first strap 201 and a second strap 202 respectively connected to both ends of the second insulation layer 104. The other end of the first strap 201 is connected to a buckle 203, and a buckle cover 204 is provided on one side of the buckle 203. The end of the second strap 202 is clamped between the buckle 203 and the buckle cover 204. Ribs 202a are provided on both sides of the second strap 202. Furthermore, the ribs 202a on both sides of the second strap 202 are staggered. The buckle seat 203 and buckle cover 204 are provided with slots 204a matching the ribs 202a. The buckle cover 204 has a first sliding groove 204b and a second sliding groove 204c on the side away from the buckle seat 203. A slider 205 is sleeved in the first sliding groove 204b. The slider 205 is arranged in a right-angled triangle. The bottom of the first sliding groove 204b slides in contact with the inclined surface of the slider 205. A screw 207 connects the slider 205, the buckle cover 204 and the buckle seat 203. A spring 206 is sleeved in the second sliding groove 204c. A screw 207 connects the spring 206, the buckle cover 204 and the buckle seat 203.

[0041] Specifically, the second strap 202 passes through the short straight edge of the slider 205 between the buckle seat 203 and the buckle cover 204, and the second strap 202 passes through the slot 204a along the long straight edge of the slider 205. The length of the inner wall of the inclined side of the first slide groove 204b is greater than the length of the inclined side of the slider 205. The bottom of the second slide groove 204c is provided with a third slide groove 204d, and the screw 207 in the second slide groove 204c is slidably connected to the third slide groove 204d. The first slide groove 204b and the second slide groove 204c are symmetrically distributed about both sides of the slot 204a.

[0042] refer to Figure 1 The fixing mechanism is obviously used by pulling the second strap 202 to reduce the loop formed by the first strap 201 and the second strap 202, thereby reducing the opening of the detection shielding mechanism 100 connected to the surge arrester 300, so that the detection shielding mechanism 100 is tightly fitted onto the surge arrester 300.

[0043] The specific working principle is as follows: when the end of the second strap 202 is pulled, the ribs 202a on the second strap 202 will exert two component forces on the buckle cover 204 through the arc surface of the slot 204a, one along the direction in which the strap passes through and the other perpendicular to the buckle cover 204 and outward. The slider 205, fixed to the buckle seat 203 by the screw 207, remains in the same position relative to the buckle seat 203. The buckle cover 204 slides along the inclined surface of the slider 205 in the direction away from the buckle seat 203, thus the buckle cover 204 no longer presses against the buckle seat 203, allowing the ribs 202a of the second strap 202 to slide through the slot 204a without being jammed. Conversely, when the end of the second strap 202 is pulled, the ribs 202a on the second strap 202 will not be jammed and will slide through the slot 204a. When the second strap 202 is pulled in the opposite direction, its upper rib 202a will drive the buckle cover 204 to move along the inclined surface of the slider 205 towards the buckle seat 203, thus tightening it more and more as it is pulled. This achieves unidirectional movement of the second strap 202 relative to the buckle seat 203 and the buckle cover 204, so that the fixing mechanism will not loosen after binding the detection mechanism. When it needs to be removed, the buckle cover 204 is pushed relative to the buckle seat 203 in the direction where the second strap 202 passes through, so that the buckle cover 204 has a small amount of room to move between the slider 205 and the buckle seat 203, and the second strap 202 can be pulled out to untie it.

[0044] The rest of the structure is the same as in Example 1.

[0045] In summary, this device effectively achieves a reliable connection between the flexible, sheet-like detection shielding mechanism 100 and the surge arrester 300.

[0046] Example 3, referring to Figure 9 and Figure 10 This is the third embodiment of the present invention. Unlike the previous embodiment, this embodiment provides a slot 204a and a rib 202a in the fixing mechanism of the surface leakage current testing device for DC leakage testing of surge arrester 300. This enables precise adjustment of the clamping force of the fixing mechanism on the detection shielding mechanism 100. The density of the slot 204a is greater than the density of the rib 202a, and the end of the screw 207 is fastened to the buckle 203.

[0047] In order for the second strap 202 to be effectively engaged with the slot 204a via the ribs 202a, the ribs 202a cannot be designed to be too small, and the spacing between the ribs 202a cannot be too small. Otherwise, the second strap 202 may not be flexible enough and may easily break due to fatigue after repeated bending. Increasing the spacing between the ribs 202a will result in less precise tightening adjustment of the second strap 202. For example, tightening it by one notch will make it too tight, while loosening it by one notch will make it too loose. Therefore, the above problems are solved by designing the ribs 202a on both sides of the second strap 202 to be staggered and spaced at a large distance, and increasing the density of the slots 204a on the buckle seat 203 and buckle cover 204.

[0048] The rest of the structure is the same as in Example 2.

[0049] In summary, this device effectively achieves precise adjustment of the clamping force of the fixing mechanism on the detection shielding mechanism 100.

[0050] It is important to note that the constructions and arrangements of this application shown in several different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those who consult this disclosure will readily understand that many modifications are possible (e.g., changes in the size, dimensions, structure, shape, and proportions of various elements, as well as parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, orientation, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in this application). For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of elements may be inverted or otherwise altered, and the nature or number or position of discrete elements may be changed or altered. Therefore, all such modifications are intended to be included within the scope of the invention. The order or sequence of any process or method steps may be changed or rearranged according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure described herein that performs the function, and not only structurally equivalent but also equivalent in structure. Other substitutions, modifications, alterations, and omissions may be made in the design, operation, and arrangement of the exemplary embodiments without departing from the scope of the invention. Therefore, the present invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0051] Furthermore, in order to provide a concise description of exemplary embodiments, not all features of actual embodiments (i.e., those features that are not relevant to the best mode of carrying out the invention as currently considered, or those features that are not relevant to implementing the invention) may be omitted.

[0052] It should be understood that numerous specific implementation decisions can be made during the development of any practical implementation, such as in any engineering or design project. Such development efforts may be complex and time-consuming, but for those skilled in the art who benefit from this disclosure, the development effort will be a routine work of design, manufacturing, and production without requiring much experimentation.

[0053] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A shielding device for testing the DC leakage current of a surge arrester, comprising a surge arrester (300), characterized in that: It also includes, The detection shielding mechanism (100) includes a terminal block (105) and a measuring layer (101). A first insulating layer (102) is attached to the outer side of the measuring layer (101), and a shielding layer (103) is attached to the side of the first insulating layer (102) away from the measuring layer (101). A second insulating layer (104) is attached to the side of the shielding layer (103) away from the first insulating layer (102). The terminal block (105) includes an inner wiring layer (105a), and the inner wiring layer (105a) is covered with an outer layer. An outer wiring layer (105c) is provided, and an insulating filler (105b) is filled between the inner wiring layer (105a) and the outer wiring layer (105c). The detection shielding mechanism (100) wraps around the surge arrester (300), and the measuring layer (101) contacts the end flange of the surge arrester (300). The shielding layer (103) contacts the skirt of the surge arrester (300). The inner wiring layer (105a) is connected to the measuring layer (101), and the outer wiring layer (105c) is connected to the shielding layer (103). The fixing mechanism includes a first strap (201) and a second strap (202) respectively connected to both ends of the second insulating layer (104). The other end of the first strap (201) is connected to a buckle seat (203), and a buckle cover (204) is provided on one side of the buckle seat (203). The end of the second strap (202) is clamped between the buckle seat (203) and the buckle cover (204). Ribs (202a) are provided on both sides of the second strap (202), and the ribs (202a) on both sides of the second strap (202) are arranged in an alternating manner. The buckle seat (203) and the buckle cover (204) are provided with slots (202a) to match the ribs (202a). 04a), the cover (204) is provided with a first groove (204b) and a second groove (204c) on the side away from the buckle seat (203), and a slider (205) is sleeved in the first groove (204b). The slider (205) is arranged in a right triangle, and the bottom of the first groove (204b) slides in contact with the inclined surface of the slider (205). A screw (207) is connected between the slider (205), the cover (204) and the buckle seat (203). A spring (206) is sleeved in the second groove (204c), and a screw (207) is connected between the spring (206), the cover (204) and the buckle seat (203). The shielding layer (103) is made of a flexible metal film, and the shielding layer (103) includes two parallel shielding strips (103a), a shielding film (103b) is disposed between the shielding strips (103a), and a connecting strip (103c) connects the shielding film (103b) and the shielding strips (103a). The shielding film (103b) in the shielding layer (103) is superimposed and glued to the first insulating layer (102), and the length and width of the shielding film (103b) are both greater than the first insulating layer (102), and the shielding strip (103a) of the shielding layer (103) is in contact with the skirt of the surge arrester (300).

2. The shielding device for testing DC leakage current of surge arresters as described in claim 1, characterized in that: The measuring layer (101) is made of a rectangular metal film, and the first insulating layer (102) is made of a rectangular insulating film. The length and width of the first insulating layer (102) are both 1.1 times that of the measuring layer (101), and the measuring layer (101) is bonded to the first insulating layer (102).

3. The shielding device for testing DC leakage current of surge arresters as described in claim 2, characterized in that: The second insulating layer (104) is made of rubber and insulating fiber composite material.

4. The shielding device for testing DC leakage current of surge arresters as described in claim 3, characterized in that: The density of the slot (204a) is greater than the density of the rib (202a), and the end of the screw (207) is fastened to the buckle (203).

5. The shielding device for testing DC leakage current of surge arresters as described in claim 4, characterized in that: The second strap (202) passes through the short straight side of the slider (205) between the buckle seat (203) and the buckle cover (204), and the second strap (202) passes through the slot (204a) along the long straight side of the slider (205).

6. The shielding device for testing DC leakage current of a surge arrester as described in claim 5, characterized in that: The length of the inclined inner wall of the first groove (204b) is greater than the length of the inclined side of the slider (205).

7. The shielding device for DC leakage current testing of surge arresters as described in claim 6, characterized in that: The bottom of the second slide groove (204c) is provided with a third slide groove (204d), and the screw (207) in the second slide groove (204c) is slidably connected to the third slide groove (204d).

8. The shielding device for testing DC leakage current of surge arresters as described in claim 7, characterized in that: The first groove (204b) and the second groove (204c) are symmetrically distributed about both sides of the slot (204a).

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