Plug-in lightning arrester for characteristic test and test connection method

Abstract

The invention discloses a plug-in lightning arrester for a characteristic test. The invention also discloses a test connection method. The plug-in lightning arrester provided by the invention can be used for carrying out characteristic test without disassembly, greatly shortens the characteristic test time of an operation site, keeps that a high-voltage electric field is completely sealed in a solid material during original operation, and has the advantages that the operation is not influenced by an external environment, and the personal safety is protected.

Description

Technical Field

[0001] This invention relates to the field of high-voltage electrical switchgear technology, specifically to a pluggable surge arrester for characteristic testing and a test connection method. Background Technology

[0002] In the past two decades, with the widespread application of gas-insulated medium-voltage switchgear such as gas-insulated switchgear and ring main units in power grid systems, the number of touchable pluggable surge arresters with grounded shields used for overvoltage protection of medium-voltage gas-insulated switchgear has been increasing. They are usually installed on the gas box or at the rear of the T-type cable terminal using a pluggable connection method.

[0003] Existing touchable pluggable surge arresters have zinc oxide varistors encased in solid insulating material. The solid insulating material is shielded by a grounding layer, and the grounding terminal of the valve core and the grounding layer on the outer surface are integrated. The high-voltage electric field is entirely contained within the solid material, and the electric field is not exposed during energized operation, ensuring that the equipment is not affected by the external environment and that personal safety is guaranteed.

[0004] According to power grid operation safety requirements, preventative tests such as voltage U1mA and leakage current of 75% U1mA at DC 1mA must be performed regularly on surge arresters in operation. Currently, the testing process requires removing the pluggable surge arrester from the gas box or cable terminal of the switchgear, connecting the surge arrester's plug-in head with an insulating sleeve (a special high-altitude voltage adapter connector is used in high-altitude areas), connecting the high-voltage end of the characteristic tester to the sleeve of the surge arrester's pluggable head, and connecting the low-voltage end to the surge arrester's grounding end. After the tests are completed, the insulating sleeve is removed, and the surge arrester is reassembled. The entire process of removal and reinstallation takes significantly more time than the testing itself, is physically demanding, and carries the risk of repeated installations.

[0005] To address the shortcomings of existing technologies, a pluggable surge arrester that can be tested without disassembly is provided. This greatly shortens the on-site characteristic testing time while maintaining the original operating conditions. The high-voltage electric field is completely enclosed in solid material, and the operation is not affected by the external environment, thus protecting personal safety. This is therefore essential. Summary of the Invention

[0006] In order to overcome the above-mentioned defects of the prior art, the purpose of the present invention is to provide a pluggable surge arrester for characteristic testing and a test connection method.

[0007] To achieve the objectives of this invention, the technical solution adopted is as follows: A pluggable surge arrester for characteristic testing includes: A grounding shielding outer shell layer installed on the outside of the pluggable surge arrester body; The plug-in surge arrester body includes a valve core structure; The upper end of the valve core structure is connected to a high-voltage electrode; The lower end of the valve core structure is connected to a grounding electrode; The valve core structure, high-voltage electrode, and grounding electrode are wrapped with a composite insulating sleeve. The upper end of the composite insulating sleeve is provided with at least one plug-in head, which is plugged into and connected to the upper bushing of the gas box of the gas-insulated switchgear or the elbow-shaped cable head.

[0008] In a preferred embodiment of the present invention, a grounding insulating sleeve is provided at the lower end of the grounding electrode, and the grounding electrode is isolated from the grounding shielding outer shell layer by the grounding insulating sleeve; In a preferred embodiment of the present invention, the plug-in head is an external conical plug-in head adapted to the bushing structure of the gas-insulated switchgear gas box or an internal conical plug-in head adapted to the elbow-shaped cable head structure.

[0009] In a preferred embodiment of the present invention, the valve core structure is a valve core structure composed of zinc oxide valve plates.

[0010] In a preferred embodiment of the present invention, the composite insulating sleeve has a built-in grounding shield ring.

[0011] In a preferred embodiment of the present invention, the grounding insulating bushing has a built-in grounding shielding ring.

[0012] In a preferred embodiment of the present invention, the grounding insulating sleeve 7 is covered with a conductive shielding layer on the inner surface of the hole through the grounding bolt and the contact surface with the grounding electrode.

[0013] In a preferred embodiment of the present invention, a conductive shielding layer is provided on the inner surface of the composite insulating sleeve at the junction of the grounding insulating sleeve and the grounding electrode.

[0014] A test connection method for a pluggable surge arrester used for characteristic testing is as follows: When the surge arrester needs to be tested for leakage current periodically after it has been put into operation, the surge arrester should not be removed from the gas box or cable terminal. Instead, the switch cabinet should be operated to the line side grounding state or the bus equipment cabinet should be operated to the grounding state. Next, disconnect the grounding copper wire of the pluggable surge arrester body, connect the high-voltage end of the characteristic tester to the grounding end of the pluggable surge arrester body, and connect the low-voltage end of the characteristic tester to the main grounding busbar of the gas box. Input DC voltage to perform DC leakage current testing.

[0015] The beneficial effects of this invention are as follows: 1) It significantly shortens the time for preventive testing of surge arresters at the commissioning site, reducing the workload and intensity of testing.

[0016] 2) It reduces the installation risks caused by repeated installation and removal of surge arresters. Attached Figure Description

[0017] Figure 1 This is a structural diagram of a direct-insertion surge arrester using an integrated grounding insulating bushing, as described in this invention.

[0018] Figure 2 This is a structural diagram of a direct-insertion surge arrester using an assembled grounding insulating bushing, as per the present invention.

[0019] Figure 3 This is a structural diagram of a T-type pluggable surge arrester using an integrated grounding insulating bushing, as described in this invention.

[0020] Figure 4 This is a structural diagram of the T-type pluggable surge arrester using an assembled grounding insulating bushing, as described in this invention.

[0021] Figure 5 This invention provides a wiring method for testing the DC leakage current of a surge arrester installed on a gas-insulated switchgear. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention. Furthermore, in the following descriptions, well-known structures and technologies are omitted to avoid unnecessarily obscuring the concept of the invention.

[0023] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description. They do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. Furthermore, terms such as "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0024] like Figure 1-4 The pluggable surge arrester shown includes a grounded shield shell layer 2 disposed outside the pluggable surge arrester body.

[0025] The plug-in surge arrester body includes a valve core structure 5, which is a valve core structure composed of zinc oxide valve plates. It is used to achieve overvoltage protection.

[0026] A high-voltage electrode 3 is connected to the upper end of the valve core structure 5 for electrical connection between the valve core structure 5 and the high-voltage charged body.

[0027] A grounding electrode 6 is connected to the lower end of the valve core structure 5 for electrical connection between the valve core structure 5 and the grounding body.

[0028] The valve core structure consists of 5, the high-voltage electrode 3, and the grounding electrode 6, all wrapped with a composite insulating sleeve 4.

[0029] The upper end of the composite insulating sleeve 4 is provided with a plug-in head 1, which is plugged into and connected to the upper bushing of the gas box of the gas-insulated switchgear or the elbow cable head.

[0030] The lower end of the grounding electrode 6 is provided with a grounding insulating sleeve 7, which isolates the grounding electrode 6 from the grounding shield shell layer.

[0031] The plug-in head 1 is an external cone plug-in head adapted to the bushing structure of the gas box of the gas-insulated switchgear or an internal cone plug-in head adapted to the elbow-shaped cable head structure.

[0032] Grounding insulating bushing 7 is cast in one piece (e.g.) Figure 1 and Figure 3 ) or assembly (such as Figure 2 and Figure 4 The grounding bolt 72 on the grounding electrode 6 is connected to the grounding electrode 6 in a manner that passes through the grounding insulating sleeve and protrudes from the end of the arrester for connection with the external grounding wire.

[0033] In a plug-in surge arrester, the grounding insulating bushing 7 has a built-in grounding shielding ring 71 that is connected to the grounding shielding outer shell layer 2 of the plug-in surge arrester body.

[0034] The composite insulation sleeve 4 of the T-type pluggable surge arrester has a built-in grounding shield ring 42.

[0035] The grounding shield rings 71 and 42 are insulated from the grounding bolt 72. When a high voltage DC voltage is applied to the grounding bolt 72, the grounding shield rings 71 and 42 shield the ends of the grounding shield shell layer 2 exposed to the air, so that the electric field concentration point is inside the solid insulating material.

[0036] Grounding insulating bushing 7 (e.g., using assembly method) Figure 2 and Figure 4 The inner surface of the grounding bolt 72 and the contact surface with the grounding electrode are covered with a conductive shielding layer 73.

[0037] A conductive shielding layer 41 is provided on the inner surface of the composite insulating sleeve 4 at the junction of the grounding insulating sleeve 7 and the grounding electrode 6. This layer is used to prevent the electric field concentration between the grounding insulating sleeve 7 and the grounding electrode 6, and between the grounding insulating sleeve 7 and the grounding bolt 72, from affecting the insulation when a high voltage DC voltage is applied to the grounding bolt 72.

[0038] When a gas-insulated switchgear or ring main unit needs to be tested for DC leakage current in a power plant, the switchgear should be moved from the operating position to the grounding position (three-position switch to grounding position, circuit breaker closed; if the switchgear is not equipped with a circuit breaker, only the three-position switch needs to be moved to the grounding position), and the main grounding wire of the pluggable surge arrester of the present invention for DC characteristic testing should be removed.

[0039] like Figure 5 As shown, the high-voltage terminal of the DC leakage current characteristic tester is connected to the grounding bolt 72 of the surge arrester of the present invention, and the grounding terminal of the DC leakage current characteristic tester is connected to the main grounding point of the gas box, and a DC voltage is applied for testing.

[0040] The working principle of this invention is as follows: The grounding electrode is insulated from the grounding shield shell (layer) by a specially designed grounding insulating bushing. Different grounding insulating bushings are designed according to different product voltage levels and altitudes, so that they can withstand the 1mA DC reference voltage of the corresponding voltage level when performing DC leakage current tests.

[0041] When the surge arrester needs to be tested for leakage current periodically after it has been put into operation, the surge arrester should not be removed from the gas box or cable terminal. Instead, the switch cabinet should be operated to the line side grounding state or the bus equipment cabinet should be operated to the grounding state. Next, disconnect the grounding copper wire of the pluggable surge arrester body, connect the high-voltage end of the characteristic tester to the grounding end of the pluggable surge arrester body, and connect the low-voltage end of the characteristic tester to the main grounding busbar of the gas box. Input DC voltage to perform DC leakage current testing.

[0042] The foregoing has shown and described the basic principles and main features of the invention and the advantages of the invention.

[0043] Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope. All such changes and modifications fall within the scope of the present invention as claimed, which is defined by the appended claims and their equivalents.

Claims

1. A plug-in surge arrester for a characteristic test, characterized by, include: A grounding shielding outer shell layer installed on the outside of the pluggable surge arrester body; The plug-in surge arrester body includes a valve core structure; The upper end of the valve core structure is connected to a high-voltage electrode; The lower end of the valve core structure is connected to a grounding electrode; The valve core structure, high-voltage electrode, and grounding electrode are wrapped with a composite insulating sleeve. The upper end of the composite insulating sleeve is provided with at least one plug-in head, which is plugged into and connected to the upper bushing of the gas box of the gas-insulated switchgear or the elbow-shaped cable head.

2. A plug-in surge arrester for property testing according to claim 1, characterized in that The lower end of the grounding electrode is provided with a grounding insulating sleeve, which isolates the grounding electrode from the grounding shielding outer shell.

3. A pluggable surge arrester for characteristic testing as described in claim 1, characterized in that, The plug-in head is either an external tapered plug-in head adapted to the bushing structure of the gas-insulated switchgear gas box or an internal tapered plug-in head adapted to the elbow-shaped cable head structure.

4. A pluggable surge arrester for characteristic testing as described in claim 1, characterized in that, The valve core structure is a valve core structure composed of zinc oxide valve plates.

5. A pluggable surge arrester for characteristic testing as described in claim 1, characterized in that, The composite insulating sleeve has a built-in grounding shield ring.

6. A pluggable surge arrester for characteristic testing as described in claim 1, characterized in that, The grounding insulating bushing has a built-in grounding shielding ring.

7. A pluggable surge arrester for characteristic testing as described in claim 1, characterized in that, The grounding insulating sleeve 7 is covered with a conductive shielding layer on the inner surface of the hole through the grounding bolt and on the contact surface with the grounding electrode.

8. A pluggable surge arrester for characteristic testing as described in claim 1, characterized in that, A conductive shielding layer is provided on the inner surface of the composite insulating sleeve at the junction of the grounding insulating sleeve and the grounding electrode.

9. A test connection method for a pluggable surge arrester used for characteristic testing as described in any one of claims 1-9, comprising: When the surge arrester needs to be tested for leakage current periodically after it has been put into operation, the surge arrester should not be removed from the gas box or cable terminal. Instead, the switch cabinet should be operated to the line side grounding state or the bus equipment cabinet should be operated to the grounding state. Next, disconnect the grounding copper wire of the pluggable surge arrester body, connect the high-voltage end of the characteristic tester to the grounding end of the pluggable surge arrester body, and connect the low-voltage end of the characteristic tester to the main grounding busbar of the gas box. Input DC voltage to perform DC leakage current testing.

Images