Cable intermediate joint sealing performance testing device

Abstract

According to the cable intermediate joint sealing performance testing device provided by the invention, the sealing performance of the cable intermediate joint can be efficiently detected through the components such as the sealing box main body, the U-shaped sealing ring and the electric negative pressure vacuum pump. The device adopts a silicone rubber U-shaped sealing ring to ensure tight fitting with the cable and reduce the risk of air leakage. And through vacuumizing to 0.9 standard atmospheric pressure and standing observation, if the air pressure is stable, the sealing is good. Compared with a traditional water seal test, the device is easy and convenient to operate, low in cost, free of planing inspection, small in size and convenient for site construction test, and the safety and maintenance efficiency of a cable system are effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of cable detection, and in particular to a cable intermediate joint sealing test device. Background Art

[0002] In the development of cities, cables have become the most commonly used power transmission and distribution lines in power systems. Because the length of power cables is limited, it is necessary to connect multiple sections of cables through intermediate heads to form a complete transmission line. The main operation of the intermediate head. When there are differences in cable types, specifications, materials, etc., the intermediate head can achieve seamless transition connection between different cables. During operation, if the intermediate joint or a certain section of the cable fails, after the fault point is removed, it can be connected through the intermediate cable joint to improve the reliability of the power supply system. It is impossible to directly detect whether the sealing performance of the installed cable intermediate joint meets the requirements. If the insulation body of this cable intermediate joint is not shrinkable, the waterproof material is unqualified, or the waterproof seal is not made as required during production, it will cause water ingress or moisture when encountering rainy days or water accumulation in cable trenches and wells. When the cable intermediate joint fails in daily operation, it is found that more than 90% of the internal parts are damp after dissection, which shows the importance of waterproof sealing. At present, in the acceptance of cable handover test projects, there is no equipment and instrument that can directly detect whether the waterproof performance of the completed intermediate joint is qualified at the construction site. Therefore, it is impossible to know whether the waterproof performance of the intermediate joint of the cable to be put into operation meets the installation quality requirements during the handover test. Therefore, the intermediate joints of the put into operation often have some waterproof defects. After a period of operation, the internal defects of the intermediate joints lead to the occurrence of faults, resulting in unsafe and unstable operation of the cable line.

[0003] At present, some tests are carried out through the ordinary water tank test method. The cable middle joint is made into a test sample. The two ends are sealed and the whole is immersed in water. Then it is placed in 1 meter deep water and immersed for 24 hours. After that, it is taken out of the water, peeled and inspected inside to determine the waterproof performance. It is impossible to directly test the cable middle joint in the handover test.

[0004] Common water tank testing methods have the following problems:

[0005] 1. The operation is complicated and the test preparation takes a long time.

[0006] 2. The test method takes a long time to verify and cannot be widely used in actual construction.

[0007] 3. To verify the test results, the middle joint of the cable needs to be dissected, which takes a long time to strip and analyze, which is a waste of time.

[0008] 4. The water tank is a detection device with large size, heavy weight and inconvenient to carry.

[0009] 5. The water tank cannot directly detect the intermediate joints of the cable during the handover test. Summary of the invention

[0010] The technical problem to be solved by the present invention is to provide a cable intermediate joint sealing test device to monitor and analyze the overall operating status of the ring network cabinet in real time and provide early warning, and intelligently link the waterproof device to ensure the safe and stable operation of the power grid equipment.

[0011] In order to solve the above technical problems, an embodiment of the present invention provides a cable intermediate joint sealing test device, comprising:

[0012] A sealed box body, wherein the sealed box body is formed by a bottom plate and four side plates connected together, an open opening is formed on the top of the sealed box body, and U-shaped grooves are formed on the tops of the left and right side plates;

[0013] Two U-shaped sealing rings, each of which is provided with a cable hole, the cable holes of the two U-shaped sealing rings are respectively used for the cables on both sides of the cable intermediate joint to pass through, and the two U-shaped sealing rings are respectively installed in the U-shaped grooves of the left and right side plates after being sleeved on the cables on both sides of the cable intermediate joint;

[0014] A sealed box upper cover, the sealed box upper cover is used to close the open opening of the sealed box body; the sealed box upper cover is provided with a pressure gauge and an exhaust pipe, the pressure gauge is used to monitor and display the air pressure value of the air pressure in the sealed box formed by the sealed box body and the sealed box upper cover, and the exhaust pipe is provided with an air valve, the air valve is used to open or close the exhaust pipe;

[0015] A sealing gasket, which is arranged at the open opening of the sealing box body and is used to seal the gap between the sealing box body and the sealing box upper cover;

[0016] An electric negative pressure vacuum pump is provided with an exhaust port and an exhaust interface, wherein the exhaust interface is used to be connected to the exhaust pipe to evacuate the sealed box, and the extracted gas is discharged through the exhaust port.

[0017] Furthermore, a flange is formed at the open mouth of the sealing box body, and a plurality of sealing connection holes are evenly distributed on the flange; a plurality of sealing connection holes are evenly distributed around the sealing box upper cover, and the plurality of sealing connection holes on the flange correspond one to one with the plurality of sealing connection holes on the sealing cover upper cover, the sealing gasket is laid on the flange, and the sealing box body and the sealing box upper cover are connected and fixed by a plurality of threaded connectors and the sealing connection holes of the two.

[0018] Furthermore, the U-shaped sealing ring is made of silicone rubber material.

[0019] Further, the method comprises:

[0020] Operating the gas valve to open the exhaust pipe;

[0021] Start the electric negative pressure vacuum pump to evacuate the sealed box and observe the air pressure value of the barometer;

[0022] When the air pressure value reaches 0.9 standard atmospheric pressure, the vacuum exhaust of the sealed box is stopped, and the air valve is operated to close the exhaust pipe;

[0023] After waiting for 24 hours, observe whether the air pressure value of the pressure gauge changes. If not, it means that the seal is good. If so, it means there is a leak.

[0024] The cable intermediate joint sealing test device provided by the embodiment of the present invention has the following beneficial effects:

[0025] (1) The sealing test device provided in the embodiment of the present invention does not require water addition or drainage, so the time for setting up and preparing for the test is greatly shortened, the sealing operation is simpler, and no complicated preparation work is required, thereby improving work efficiency.

[0026] (2) The embodiment of the present invention does not require the use of water resources, and there is no need to dissect the cable intermediate joint for inspection after the test is completed, thereby saving cost and time. The sealing performance of the cable intermediate joint can be directly judged by the change in air pressure, reducing the waste of materials and time.

[0027] (3) Unlike the water tank test method, the embodiment of the present invention uses a gas sealing method for testing, which is not affected by the sealing effect of both ends of the cable, so the test result is more reliable. In addition, the device of the embodiment of the present invention can be used for the intermediate joint of the handover test or operation, and has a wider range of applications.

[0028] (4) Since the device of the embodiment of the present invention is small in size, easy to carry and use on site, does not require additional auxiliary materials, and only requires a small vacuum pump, it is more convenient during on-site cable construction, preventive testing, or handover test acceptance.

[0029] (5) The device of the embodiment of the present invention can perform a handover test on the manufactured cable intermediate joints before the cable is put into operation, or perform a preventive test on the intermediate joints during cable operation. This is an important advancement in the field of cable power distribution, which helps to discover potential problems in advance and ensure the safe and stable operation of the cable system.

[0030] In summary, the cable intermediate joint sealing test device provided by the embodiment of the present invention has significant technical and economic benefits in practical applications, and helps to improve the maintenance and management level of the cable system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0032] Figure 1 It is a front view of a cable intermediate joint sealing test device in an embodiment of the present invention.

[0033] Figure 2 It is a cross-sectional view of the AA plane of a cable intermediate joint sealing test device in an embodiment of the present invention.

[0034] Figure 3 This is a top view of a cable intermediate joint sealing test device in an embodiment of the present invention.

[0035] Figure 4 It is a stereoscopic diagram of a cable intermediate joint sealing test device in an embodiment of the present invention.

[0036] Figure 5 Schematic diagram of the structure of an electric negative pressure vacuum pump in an embodiment of the present invention.

[0037] Figure 6 It is a schematic diagram of the connection between the electric negative pressure vacuum pump and the cable intermediate joint sealing test device in an embodiment of the present invention.

[0038] Figure 7 The figure is a schematic diagram of the connection between the U-shaped sealing ring, the middle joint of the cable and the cables at both ends in the embodiment of the present invention. DETAILED DESCRIPTION

[0039] The detailed description of the drawings is intended as an illustration of the current embodiment of the present application, and is not intended to represent the only form in which the present application can be implemented. It should be understood that the same or equivalent functions can be accomplished by different embodiments intended to be included in the spirit and scope of the present application.

[0040] See also Figures 1 to 7 The embodiment of the present invention provides a cable intermediate joint sealing test device, comprising:

[0041] A sealed box body, wherein the sealed box body is formed by a bottom plate and four side plates connected together, an open opening is formed on the top of the sealed box body, and U-shaped grooves are formed on the tops of the left and right side plates;

[0042] Two U-shaped sealing rings, each of which is provided with a cable hole, the cable holes of the two U-shaped sealing rings are respectively used for the cables on both sides of the cable intermediate joint to pass through, and the two U-shaped sealing rings are respectively installed in the U-shaped grooves of the left and right side plates after being sleeved on the cables on both sides of the cable intermediate joint;

[0043] A sealed box upper cover, the sealed box upper cover is used to close the open opening of the sealed box body; the sealed box upper cover is provided with a pressure gauge and an exhaust pipe, the pressure gauge is used to monitor and display the air pressure value of the air pressure in the sealed box formed by the sealed box body and the sealed box upper cover, and the exhaust pipe is provided with an air valve, the air valve is used to open or close the exhaust pipe;

[0044] A sealing gasket, which is arranged at the open opening of the sealing box body and is used to seal the gap between the sealing box body and the sealing box upper cover;

[0045] An electric negative pressure vacuum pump is provided with an exhaust port and an exhaust interface, wherein the exhaust interface is used to be connected to the exhaust pipe to evacuate the sealed box, and the extracted gas is discharged through the exhaust port.

[0046] Specifically, the main body of the sealing box is formed by a bottom plate and four side plates (front, rear, left and right) that are enclosed and connected, and these plates together form a container for placing the cable intermediate joint. There is no cover plate on the top of the sealing box body, leaving an open mouth so that the cable intermediate joint can be put in or taken out. A U-shaped groove is opened on the top of each of the left and right side plates, and these grooves are used to fix the U-shaped sealing ring. Each U-shaped sealing ring has a hole, called a cable hole, and the size of these holes is sufficient for the cable to pass through. The cable holes of the two U-shaped sealing rings are used to allow the cables on both sides of the cable intermediate joint to pass through. After the cable passes through the U-shaped sealing ring, the U-shaped sealing ring is installed in the U-shaped groove of the left and right side plates to ensure the sealing between the cable passing part and the sealing box. The upper cover of the sealing box is used to close the open mouth of the sealing box body, so that the entire device forms a sealed space. A barometer is set on the upper cover of the sealing box to monitor and display the air pressure value in the sealing box. The exhaust pipe is used to connect an electric negative pressure vacuum pump to perform a vacuum operation on the inside of the sealing box. The exhaust pipe is provided with an air valve for controlling the opening and closing of the exhaust pipe, thereby controlling the air pressure inside the sealed box. The sealing gasket is located at the opening of the sealed box body. When the upper cover is closed, the sealing gasket is used to fill the gap between the sealed box body and the upper cover to ensure the sealing of the entire device.

[0047] The electric negative pressure vacuum pump is used to evacuate the inside of the sealed box to test the sealing of the cable middle joint. The air extraction interface is connected to the exhaust pipe of the upper cover of the sealed box, and the exhaust port is used to discharge the extracted gas out of the pump. During the test, place the cable middle joint into the main body of the sealed box, and make sure that the cable passes through the U-shaped sealing ring, install the U-shaped sealing ring into the U-shaped groove of the left and right side panels, place the sealing gasket at the open mouth, and then cover the upper cover of the sealed box. Use the electric negative pressure vacuum pump to evacuate the inside of the sealed box through the exhaust pipe, and observe the reading of the barometer. If the air pressure can be maintained at a certain level (such as 0.9 standard air pressure) for a period of time (such as 24 hours), it means that the sealing of the cable middle joint is good.

[0048] In summary, the device of this embodiment can effectively test the sealing performance of the cable intermediate joint by vacuuming and monitoring the air pressure without using water or other liquid media, thereby improving the efficiency and safety of the test.

[0049] Specifically, the design size of the sealing box body is 1600mm (length) * 400mm (width) * 400mm (height), and this size is determined based on the length of the cable wrapping after the middle head is connected and the maximum outer diameter of the cable after wrapping. The length is 1600mm, which is enough to accommodate the wrapping length of the middle head of the cable (about 1.5 meters), and leave a certain margin to facilitate the placement and operation of the cable. The width and height are both 400mm. This size takes into account the maximum outer diameter of the cable after wrapping (about 30CM), ensuring that the cable can be smoothly placed in the sealing box, and providing sufficient space in height for sealing operations. Compared with traditional water-tightness testing devices, the height of the device in this embodiment is reduced to one-third of the original, which means that the device is more compact and easy to carry and store, while also reducing the use of materials and reducing costs.

[0050] The U-shaped sealing ring is put into the cable end at the beginning of making the cable middle joint. The U-shaped sealing ring is moved to a position about 1 meter away from the cable end to ensure that the sealing ring covers the connecting part of the cable middle joint, but not too close to the joint to avoid affecting the connection and wrapping of the joint, providing sufficient sealing length to ensure that during the vacuum test, the sealing ring can effectively seal the joint between the cable and the sealing box to prevent air leakage.

[0051] Furthermore, a flange is formed at the open mouth of the sealing box body, and a plurality of sealing connection holes are evenly distributed on the flange; a plurality of sealing connection holes are evenly distributed around the sealing box upper cover, and the plurality of sealing connection holes on the flange correspond one to one with the plurality of sealing connection holes on the sealing cover upper cover, the sealing gasket is laid on the flange, and the sealing box body and the sealing box upper cover are connected and fixed by a plurality of threaded connectors and the sealing connection holes of the two.

[0052] Specifically, a flange is designed at the open mouth of the sealing box body. The flange is a protruding edge portion that surrounds the open mouth and provides a flat surface for connection with the upper cover of the sealing box. A plurality of sealing connection holes are evenly distributed on the flange, and these holes are used to fix the sealing box body and the upper cover of the sealing box together through threaded connectors. A plurality of sealing connection holes are also evenly distributed around the edges of the upper cover of the sealing box, and the positions of these holes correspond to the sealing connection holes on the flange of the sealing box body. When the upper cover of the sealing box is placed on the sealing box body, the sealing connection holes of the upper cover will be aligned with the sealing connection holes of the flange. The sealing gasket is laid on the flange, and its function is to form a sealing barrier between the sealing box body and the upper cover of the sealing box to prevent air leakage. The sealing gasket is usually a soft and elastic material, such as rubber or silicone, which can fill the small gap between the two. Threaded connectors (such as bolts and nuts) are used to pass through the sealing connection holes of the flange of the sealing box body and the upper cover of the sealing box to tightly fix the two together. Each threaded connector passes through a corresponding sealing connection hole and is fixed with a nut under the upper cover, thereby ensuring that the connection between the sealing box body and the upper cover is both firm and sealed. Lay the sealing gasket on the flange platform to ensure that it covers the entire surface of the flange platform. Place the upper cover of the sealing box on the sealing box body so that the sealing connection holes of the upper cover are aligned with the sealing connection holes of the flange platform. Through the threaded connectors (bolts and nuts) passing through the corresponding sealing connection holes, the sealing box body and the upper cover of the sealing box are tightly connected. Tighten the nuts until the appropriate sealing pressure is reached between the flange platform and the upper cover of the sealing box to ensure that there is no air leakage. This design ensures that the sealing box can maintain a good sealing state during the vacuum test, and there will be no air leakage due to loose connection, which will affect the accuracy of the test results. At the same time, this structure is also convenient for disassembly and reassembly after the test is completed for the next test.

[0053] Furthermore, the U-shaped sealing ring is made of silicone rubber material.

[0054] Specifically, silicone rubber is a synthetic rubber with excellent heat resistance, cold resistance, chemical resistance and electrical insulation. It is very suitable for applications that require long-term sealing performance. The excellent radial contraction force of silicone rubber materials means that after installation, the sealing ring can produce a contraction effect in its radial direction, so that the inside of the sealing ring fits tightly with the cable surface. This contraction force ensures that even if there is a small gap between the cable and the sealing ring or the cable diameter fluctuates, the sealing ring can maintain good sealing performance and prevent medium leakage. Due to the radial contraction force of the silicone rubber U-shaped sealing ring, it can effectively fill and adapt to the irregularities on the cable surface, thereby forming a reliable sealing barrier at the connection between the cable passing through the sealing box body and the upper cover.

[0055] In applications such as vacuum testing or high-voltage testing, this tight-fitting sealing performance is particularly important because it ensures the accuracy and safety of the test. The use of a silicone rubber U-shaped sealing ring not only improves the sealing performance of the sealing box, but also because of its aging resistance, UV resistance, ozone resistance and other properties, the sealing ring can still maintain stable performance during long-term use. In addition, silicone rubber materials generally have good physical and chemical stability, can maintain their performance under a variety of environmental conditions, and extend the service life of the sealing ring. Another embodiment of the present application proposes a testing method for a cable intermediate joint sealing test device as described in the above embodiment, the method comprising the following steps:

[0056] Operating the gas valve to open the exhaust pipe;

[0057] Start the electric negative pressure vacuum pump to evacuate the sealed box and observe the air pressure value of the barometer;

[0058] When the air pressure value reaches 0.9 standard atmospheric pressure, the vacuum exhaust of the sealed box is stopped, and the air valve is operated to close the exhaust pipe;

[0059] After waiting for 24 hours, observe whether the air pressure value of the pressure gauge changes. If not, it means that the seal is good. The sealing box can be used for the protection and sealing of the cable intermediate head. You only need to close the air valve. The electric vacuum pump is not needed in non-test scenarios. If yes, it means there is a leak and you need to remake the sealing box.

[0060] Specifically, according to P = ρgh, where ρ is the density of the liquid, g is the acceleration due to gravity, and h is the depth of the liquid, for water, its density ρ = 1000kg / m3ρ = 1000kg / m3, and the acceleration due to gravity g = 10m / s2g = 10m / s2, so the pressure at a depth of 1 meter is:

[0061] P=1000kg / m3×10m / s2×1m=10000Pa;

[0062] It is about 0.1 standard atmospheric pressure. Therefore, when the air pressure in the sealed box is 0.9 standard atmospheric pressure, the pressure difference between the inside and outside of the box is 0.1 standard atmospheric pressure. Therefore, when the pressure gauge shows 0.9 standard atmospheric pressure, stop exhausting, close the air valve, and leave the sealed box still for 24 hours, then observe whether the pressure value on the pressure gauge has changed.

[0063] If the air pressure value changes, it means that the cable middle head has air leakage and poor sealing, and needs to be remade. If the air pressure value does not change, it means that the cable middle head has good sealing and can be put into use. If you need to shorten the static time, you can reduce the air pressure value in the sealing box, increase the internal and external pressure difference, and shorten the test static time through the large pressure difference.

[0064] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A cable intermediate joint sealing test device, characterized in that: include: A sealed box body, wherein the sealed box body is formed by a bottom plate and four side plates connected together, an open opening is formed on the top of the sealed box body, and U-shaped grooves are formed on the tops of the left and right side plates; Two U-shaped sealing rings, each of which is provided with a cable hole, the cable holes of the two U-shaped sealing rings are respectively used for the cables on both sides of the cable intermediate joint to pass through, and the two U-shaped sealing rings are respectively installed in the U-shaped grooves of the left and right side plates after being sleeved on the cables on both sides of the cable intermediate joint; A sealed box upper cover, the sealed box upper cover is used to close the open opening of the sealed box body; the sealed box upper cover is provided with a pressure gauge and an exhaust pipe, the pressure gauge is used to monitor and display the air pressure value of the air pressure in the sealed box formed by the sealed box body and the sealed box upper cover, and the exhaust pipe is provided with an air valve, the air valve is used to open or close the exhaust pipe; A sealing gasket, which is arranged at the open opening of the sealing box body and is used to seal the gap between the sealing box body and the sealing box upper cover; An electric negative pressure vacuum pump is provided with an exhaust port and an exhaust interface, wherein the exhaust interface is used to be connected to the exhaust pipe to evacuate the sealed box, and the extracted gas is discharged through the exhaust port.

2. The cable intermediate joint sealing test device according to claim 1, characterized in that: A flange is formed at the open mouth of the sealing box body, and a plurality of sealing connection holes are evenly distributed on the flange; a plurality of sealing connection holes are evenly distributed around the sealing box upper cover, and the plurality of sealing connection holes on the flange correspond one to one with the plurality of sealing connection holes on the sealing cover upper cover, the sealing gasket is laid on the flange, and the sealing box body and the sealing box upper cover are connected and fixed by a plurality of threaded connectors and the sealing connection holes of the two.

3. The cable intermediate joint sealing test device according to claim 1, characterized in that: The U-shaped sealing ring is made of silicone rubber material.

4. The cable intermediate joint sealing test method according to claim 1, characterized in that: The method comprises: Operating the gas valve to open the exhaust pipe; Start the electric negative pressure vacuum pump to evacuate the sealed box and observe the air pressure value of the barometer; When the air pressure value reaches 0.9 standard atmospheric pressure, the vacuum exhaust of the sealed box is stopped, and the air valve is operated to close the exhaust pipe; After waiting for 24 hours, observe whether the air pressure value of the pressure gauge changes. If not, it means that the seal is good. If so, it means there is a leak.

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