35kv and below cable t-joint withstand voltage detection device and working method thereof

Abstract

The present application relates to a kind of 35kV and below cable T joint withstand voltage detection device and its working method, including T type sleeve, T type sleeve transverse both ends and vertical bottom end are opened and inside intercommunication, first connecting component and second connecting component are transversely coaxially arranged in T type sleeve, first connecting component and second connecting component are respectively inserted from the opposite ends of T type sleeve and threadedly connected, first conductor is coaxially sleeved with first insulating sleeve, conical plug is sleeved on the outside of first insulating sleeve, and the inner end of first conductor is fixed with first flange along its outer periphery;Second conductor is coaxially sleeved with second insulating sleeve, and second conductor is fixed with second flange along its outer periphery near the side of first conductor, and second flange and first flange are clamped with cable, which is inserted from the vertical opening end of T type sleeve, the used 35kV and below cable T joint withstand voltage detection device is simple in structure, strong in applicability, safer and more convenient.

Description

Technical Field

[0001] This invention relates to a withstand voltage testing device for T-joints of cables of 35kV and below and its working method. Background Technology

[0002] During cable handover tests and routine maintenance tests, the test voltage can reach several times the rated voltage of the line, approaching or exceeding the insulation withstand voltage values ​​of the electrical and mechanical parameters of the cable accessory materials. This can cause surface leakage and creepage in the accessories and the cable itself, leading to potential defects and, in severe cases, damage to the testing and tested equipment. Furthermore, in many tests, the T-joints (including elbow joints) are often disassembled before testing, making it impossible to assess the operational status of the T-joints, which clearly does not comply with regulations. In addition, the T-joints are closely fitted to the cable ends; repeated disassembly and reassembly reduce work efficiency and easily damage related accessories.

[0003] Research on safe connection devices for cable terminal withstand voltage tests is limited. The published patent CN202110613176.4, "An Insulation Protection Device for Cable Withstand Voltage Test and Its Use," proposes a withstand voltage test device that uses a conductor to lead the cable lug to the outside of the T-joint, and uses an insulating component similar to a sealing cap to seal the opening of the T-joint for grounding. However, it has the following drawbacks:

[0004] 1. The internal conductors are exposed. Due to long-term operation and environmental influences, the T-joint section is contaminated. The conductors may discharge contaminants inside the T-joint, which may damage the T-joint.

[0005] 2. The conductor makes contact and conducts voltage by passing through the lug. However, since the cross-section of the cable and the size of the lug vary for the same voltage level and different manufacturers, the conductor cannot be guaranteed to fit perfectly with the hole of the lug. Therefore, this connection method has the disadvantage of poor contact.

[0006] 3. Under the same voltage level, the size of the T-connector varies greatly due to differences in manufacturers and cable cross-sections. This device uses a cap-type plug, which can only be used for T-connectors of the same size, resulting in poor applicability. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a withstand voltage testing device and its working method for cable T-joints of 35kV and below, which is not only reasonable in structure, but also safe and convenient.

[0008] To solve the above-mentioned technical problems, the technical solution of the present invention is: a withstand voltage testing device for T-joints of cables of 35kV and below, comprising a T-shaped bushing, wherein both ends of the T-shaped bushing are open in the horizontal direction and the bottom end is open in the vertical direction and are interconnected internally, and a first connecting component and a second connecting component are coaxially inserted in the horizontal direction inside the T-shaped bushing, wherein the first connecting component and the second connecting component are respectively inserted into each other from both ends of the horizontal direction of the T-shaped bushing and threadedly connected, the first connecting component comprising a first conductor, a first insulating sleeve, a first flange and a conical plug, wherein the first insulating sleeve is coaxially fitted outside the first conductor, the conical plug is fitted outside the first insulating sleeve, and the first flange is fixedly provided along its outer periphery at the inner end of the first conductor; the second connecting component comprising a second conductor, a second insulating sleeve and a second flange, wherein the second insulating sleeve is coaxially fitted outside the second conductor, and the second flange is fixedly provided along its outer periphery on the side of the second conductor near the first conductor, wherein a cable extending from the vertical opening end of the T-shaped bushing is sandwiched between the second flange and the first flange.

[0009] Furthermore, the first conductor is fixedly connected to the first insulating sleeve, and a threaded hole is opened at the center of one end of the flange of the first conductor. The tapered plug is slidably connected to the first insulating sleeve on the same axis.

[0010] Furthermore, one end of the second conductor is embedded and fixed inside the second insulating sleeve, and the other end extends out of the insulating sleeve and has an external thread along its outer circumference that is screwed into a threaded hole. The second flange is provided on the extended end of the second conductor.

[0011] Furthermore, the end of the first conductor furthest from the second conductor extends laterally through the first insulating sleeve to facilitate connection with the withstand voltage testing mechanism.

[0012] Furthermore, a cable lug is fixedly connected to the end of the cable.

[0013] Furthermore, an arc-shaped limiting block is fixed to the top of the inner wall of the T-shaped sleeve located between the first connecting component and the second connecting component. The bottom of the arc-shaped limiting block is recessed with an arc-shaped limiting groove to facilitate the insertion and limiting of the top of the wire nose.

[0014] The operating method for the withstand voltage testing device for 35kV and below cable T-joints shall be carried out according to the following steps:

[0015] S1: Provide a cable with a wire lug connected to the top end of the cable;

[0016] S2: Insert the cable and lug into the T-shaped sleeve from the bottom opening of the T-shaped sleeve, and insert the top of the lug into the arc-shaped limiting groove;

[0017] S3: Insert the first connecting component and the second connecting component facing each other, and make the end of the second conductor pass through the through hole of the wire lug, and put the second flange against the surface of the wire lug;

[0018] S4: Tighten the second insulating sleeve, and screw the end of the second conductor into the threaded hole of the first conductor through the external thread to complete the connection of the two conductors;

[0019] S5: Push the conical plug from the outside in to seal the T-shaped sleeve opening on the side where the first connecting component is located;

[0020] S6: Connect the outer end of the first conductor to the withstand voltage testing mechanism and perform a withstand voltage test.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. By using this safety connection device, the conductive part inside the terminal is extended to the outside of the T-connector, increasing the air gap and preventing creepage.

[0023] 2. It adopts a double-layer structure, with an inner conductor and an outer insulating layer, which can significantly weaken the electric field.

[0024] 3. The device uses a threaded connection method for the connecting components, and by adjusting the screw insertion depth, it can adapt to T-joints of various lengths.

[0025] 4. The front part of the device uses a conical plug to isolate the air gap.

[0026] 5. The plug design with a large slope, combined with the flexibility of silicone rubber, can effectively adapt to most T-joints on the market.

[0027] 6. The rear half of the device uses a short conductor rod to cooperate with the front half for fixation, while the rest is insulated. The second conductor is not completely continuous, which can weaken the electric field strength at the rear opening of the T-joint.

[0028] This device comprehensively considers the calculation of electric field strength and creepage distance, ensuring that no creepage occurs inside the T-joint during withstand voltage tests of 35kV and below cables at three times the rated voltage, thus guaranteeing the safety of test personnel. Furthermore, the threaded locking design of the tapered plug ensures that this connection device is applicable to all T-joint models above 35kV, providing convenience for test personnel to a certain extent.

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0030] Figure 1 This is a schematic diagram illustrating the structure of an embodiment of the present invention;

[0031] Figure 2 This is a side view of an embodiment of the present invention;

[0032] Figure 3 for Figure 2 Sectional view of AA;

[0033] Figure 4 for Figure 3 Enlarged diagram of B in the middle;

[0034] Figure 5 This is a schematic diagram of the construction of the conical plug in an embodiment of the present invention.

[0035] In the figure: 1-T-type sleeve, 2-first connecting assembly, 3-second connecting assembly, 4-first conductor, 5-first insulating sleeve, 6-first flange, 7-conical plug, 8-second conductor, 9-second insulating sleeve, 10-second flange, 11-cable, 12-threaded hole, 13-external thread, 14-line lug, 15-arc-shaped limiting block, 16-arc-shaped limiting groove. Detailed Implementation

[0036] To make the above features and advantages of the present invention more apparent and understandable, specific embodiments are described below in conjunction with the accompanying drawings for detailed explanation.

[0037] like Figures 1-5 As shown, a withstand voltage testing device for T-joints of cables of 35kV and below includes a T-shaped bushing 1. The T-shaped bushing has openings at both ends in the horizontal direction and at the bottom in the vertical direction, and the openings are interconnected internally. A first connecting component 2 and a second connecting component 3 are coaxially inserted into the T-shaped bushing in the horizontal direction. The first connecting component and the second connecting component are respectively inserted into each other from both ends in the horizontal direction of the T-shaped bushing and threaded together. The first connecting component includes a first conductor 4, a first insulating sleeve 5, a first flange 6, and a conical plug 7. The first insulating sleeve is coaxially fitted outside the first conductor, and the conical plug is fitted outside the first insulating sleeve. The first flange is fixedly provided along the outer periphery of the inner end of the first conductor. The second connecting component includes a second conductor 8, a second insulating sleeve 9, and a second flange 10. The second insulating sleeve is coaxially fitted outside the second conductor. The second flange is fixedly provided along the outer periphery of the second conductor on the side closer to the first conductor. A cable 11 extending from the vertical opening end of the T-shaped bushing is sandwiched between the second flange and the first flange.

[0038] In this embodiment of the invention, both the first and second conductors are made of copper (not limited to copper; any material with good conductivity is acceptable). The first insulating sleeve, the second insulating sleeve, and the conical plug are all made of silicone rubber (not limited to silicone rubber; applicable to all insulating materials). The two conductors serve to connect and extend the internal lugs of the T-joint, and a disc-shaped flange is designed at the connection point with the lugs to increase the contact surface with the lugs. The intermediate locking conductor rod is threaded to ensure good contact between the conductor and the lugs. When the T-joint is long, the screw insertion depth can be adjusted to ensure that the two conductors can be properly connected. The first flange cannot simultaneously press the cable lug tightly, but it still ensures that the second flange is in close contact with the cable lug. The length of the first conductor is slightly longer than the insulation layer, and the extended part serves as the connection point for the test pressurization equipment, that is, to apply pressure to the cable head from the outside and reduce the creepage distance. An insulation layer (sleeve) is cast outside the first conductor to weaken the electric field strength around the device and prevent creepage. The conical plug can be slidably connected or cast and fixedly connected outside the insulation layer, which serves to seal the air gap of the T-joint opening, block the creepage channel, and control its slope, so that the sealing reliability can still be guaranteed under different sizes of T-joint openings. The second connecting component consists of a second conductor and a second insulating sleeve (materials same as the first half). Its main function is to connect to the first connecting component and ensure no creepage. Therefore, its second conductor is relatively short, only extending to a small section of the insulating sleeve, and the rest is insulation. This design can significantly weaken the electric field. It is calculated that the electric field strength at the opening is less than 1kV / mm, so the second connecting component does not need to be sealed with a plug.

[0039] In this embodiment of the invention, the first conductor is fixedly connected to the first insulating sleeve, and a threaded hole 12 is provided at the center of one end of the flange of the first conductor. The tapered plug is slidably connected to the first insulating sleeve on the same axis.

[0040] In this embodiment of the invention, one end of the second conductor is embedded and fixed inside the second insulating sleeve, and the other end extends out of the insulating sleeve and is provided with an external thread 13 along its outer periphery for screwing into a threaded hole. The second flange is provided on the extended end of the second conductor.

[0041] In this embodiment of the invention, the end of the first conductor away from the second conductor extends laterally through the first insulating sleeve to facilitate connection with the withstand voltage testing mechanism.

[0042] In this embodiment of the invention, a cable lug 14 is fixedly connected to the end of the cable.

[0043] In this embodiment of the invention, an arc-shaped limiting block 15 is fixedly provided on the top of the inner wall of the T-shaped sleeve between the first connecting component and the second connecting component. The bottom of the arc-shaped limiting block is recessed with an arc-shaped limiting groove 16 to allow the top of the wire nose to be inserted and limited.

[0044] The operating method for the withstand voltage testing device for 35kV and below cable T-joints shall be carried out according to the following steps:

[0045] S1: Provide a cable with a wire lug connected to the top end of the cable;

[0046] S2: Insert the cable and lug into the T-shaped sleeve from the bottom opening of the T-shaped sleeve, and insert the top of the lug into the arc-shaped limiting groove;

[0047] S3: Insert the first connecting component and the second connecting component facing each other, and make the end of the second conductor pass through the through hole of the wire lug, and put the second flange against the surface of the wire lug;

[0048] S4: Tighten the second insulating sleeve, and screw the end of the second conductor into the threaded hole of the first conductor through the external thread to complete the connection of the two conductors;

[0049] S5: Push the conical plug from the outside in to seal the T-shaped sleeve opening on the side where the first connecting component is located;

[0050] S6: Connect the outer end of the first conductor to the withstand voltage testing mechanism and perform a withstand voltage test.

[0051] This invention is not limited to the preferred embodiment described above. Anyone inspired by this invention can derive various other forms of withstand voltage testing devices and operating methods for 35kV and below cable T-joints. All equivalent variations and modifications made within the scope of the claims of this invention should be considered within the scope of this invention.

Claims

1. A withstand voltage testing device for T-joints of cables of 35kV and below, characterized in that: The device includes a T-shaped sleeve, which is open at both ends laterally and at the bottom vertically and is internally interconnected. A first connecting component and a second connecting component are coaxially inserted laterally inside the T-shaped sleeve. The first connecting component and the second connecting component are inserted into each other from both ends of the T-shaped sleeve and threaded together. The first connecting component includes a first conductor, a first insulating sleeve, a first flange, and a conical plug. The first insulating sleeve is coaxially fitted over the first conductor, and the conical plug is fitted over the outside of the first insulating sleeve. The first flange is fixedly provided along the outer periphery of the inner end of the first conductor. The second connecting component includes a second conductor, a second insulating sleeve, and a second flange. The second insulating sleeve is coaxially fitted over the second conductor, and the second flange is fixedly provided along the outer periphery of the second conductor near the first conductor. A cable extending from the vertically open end of the T-shaped sleeve is sandwiched between the second flange and the first flange. A wire lug is fixedly connected to the end of the cable; an arc-shaped limiting block is fixedly provided on the top of the inner wall of the T-shaped sleeve located between the first connecting component and the second connecting component, and the bottom of the arc-shaped limiting block is recessed upward to facilitate the insertion and limiting of the top of the wire lug.

2. The withstand voltage testing device for 35kV and below cable T-joints according to claim 1, characterized in that: The first conductor is fixedly connected to the first insulating sleeve. The first conductor has a threaded hole at the center of one end of the flange. The tapered plug is slidably connected to the first insulating sleeve on the same axis.

3. The withstand voltage testing device for 35kV and below cable T-joints according to claim 2, characterized in that: One end of the second conductor is embedded and fixed inside the second insulating sleeve, and the other end extends out of the insulating sleeve and has an external thread along its outer circumference that is screwed into a threaded hole. The second flange is provided on the extended end of the second conductor.

4. The withstand voltage testing device for 35kV and below cable T-joints according to claim 1, characterized in that: The end of the first conductor furthest from the second conductor extends laterally through the first insulating sleeve to facilitate connection with the withstand voltage testing mechanism.

5. A method for operating a withstand voltage testing device for T-joints of cables of 35kV and below, characterized in that, The withstand voltage testing device for cable T-joints of 35kV and below, as described in any one of claims 1-4, is used, and the following steps are performed: S1: Provide a cable with a wire lug connected to the top end of the cable; S2: Insert the cable and lug into the T-shaped sleeve from the bottom opening of the T-shaped sleeve, and insert the top of the lug into the arc-shaped limiting groove; S3: Insert the first connecting component and the second connecting component facing each other, and make the end of the second conductor pass through the through hole of the wire lug, and put the second flange against the surface of the wire lug; S4: Tighten the second insulating sleeve, and screw the end of the second conductor into the threaded hole of the first conductor through the external thread to complete the connection of the two conductors; S5: Push the conical plug from the outside in to seal the T-shaped sleeve opening on the side where the first connecting component is located; S6: Connect the outer end of the first conductor to the withstand voltage testing mechanism and perform a withstand voltage test.

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