Cable terminal and method for pressure control of a cable terminal

Abstract

The application discloses a cable terminal and a gas pressure control method of the cable terminal. The cable terminal comprises a terminal main body, a gas feeding unit, a gas discharging unit, a controller and a gas pressure sensor. The terminal main body is internally provided with a gas cavity. The gas feeding unit comprises a gas source, a gas feeding pipe and a first control valve. One end of the gas feeding pipe is communicated with the gas source, the other end is communicated with the gas cavity, and the first control valve is connected to the gas feeding pipe. The gas discharging unit comprises a gas discharging pipe and a second control valve. The gas discharging pipe is communicated with the gas cavity, and the second control valve is connected to the gas discharging pipe. The gas pressure sensor is connected to the terminal main body and at least partially arranged in the gas cavity. The gas pressure sensor, the first control valve and the second control valve are respectively electrically connected to the controller. The controller is provided with a wireless communication module, and the controller can send an alarm signal to a remote terminal through the wireless communication module. According to the technical scheme, the radial holding force is applied to the cable through the gas pressure, the stable clamping of the terminal main body to the cable is ensured, and the automatic repair of the gas pressure and the remote monitoring can be realized.

Description

Technical Field

[0001] This application relates to the field of cable fittings technology, and in particular to a cable terminal and a method for controlling the air pressure of the cable terminal. Background Technology

[0002] Cable terminations are used to achieve electrical connections and insulation protection at the ends of cables. Currently, power distribution lines widely use silicone rubber cold-shrink cable terminations, which rely on the elastic material itself to shrink and tightly grip the cable layers. However, over long-term operation, silicone rubber is affected by factors such as material aging and low-temperature environments, resulting in a continuous decrease in its shrinkage modulus and a gradual weakening of its gripping force. This leads to air gaps at the termination-to-cable interface, easily causing partial discharge and even insulation breakdown faults. Furthermore, once a cold-shrink cable termination suffers fatigue damage, no adjustment or repair can be made. When the gripping force decays to a critical value, the entire termination must be removed and replaced, resulting in long power outages and high maintenance costs. Summary of the Invention

[0003] This application aims to overcome the problems of irreversible reduction in clamping force, inability to repair, and lack of monitoring of operating status caused by rubber aging and low temperature in traditional cold shrink terminals. To this end, this application proposes a cable terminal.

[0004] This application also proposes a pneumatic control method for the aforementioned cable terminals.

[0005] A cable terminal according to a first aspect embodiment of this application includes a terminal body, an air supply unit, an exhaust unit, and an electronic control unit. The terminal body has an internal air cavity and two opposing end walls, each with a insertion hole for a cable to pass through. The air supply unit includes an air source, an air supply pipe, and a first control valve. One end of the air supply pipe is connected to the air source, and the other end passes through the first end wall to communicate with the air cavity. The first control valve is connected to the air supply pipe. The exhaust unit includes an exhaust pipe and a second control valve. One end of the exhaust pipe passes through the second end wall to communicate with the air cavity, and the second control valve is connected to the exhaust pipe. The electronic control unit includes a controller and a pressure sensor. The pressure sensor is connected to the terminal body and at least partially disposed in the air cavity. The pressure sensor, the first control valve, and the second control valve are electrically connected to the controller. The controller controls the opening or closing of the first control valve and the second control valve based on the pressure value fed back by the pressure sensor. The controller has a wireless communication module, which enables it to send alarm signals to a remote terminal.

[0006] The cable terminal according to the embodiments of this application has at least the following beneficial effects: By setting an air chamber inside the terminal body and configuring an electronic control system consisting of a controller, an air pressure sensor, a first control valve, and a second control valve, the active application and dynamic maintenance of air chamber pressure are realized. Using air pressure as a pressure source, a radial clamping force is continuously applied to the cable through gas pressure, thereby ensuring the stable clamping of the cable by the terminal body. The controller automatically controls the opening or closing of the first and second control valves based on the air pressure value fed back by the air pressure sensor, realizing automatic air replenishment and repair when air pressure drops and automatic air venting protection when overpressure occurs, overcoming the problem of irreversible attenuation of clamping force caused by rubber aging and low temperature in traditional cold-shrink terminals. Simultaneously, the controller has a wireless communication module, which can send alarm signals to remote terminals through the wireless communication module, allowing maintenance personnel to know the terminal's operating status without going to the site, further improving the intelligent operation and maintenance level of the cable terminal.

[0007] According to some embodiments of this application, the terminal body includes a shell, a stress cone, and a rain skirt. The air cavity is disposed inside the shell, and the two ends of the shell are respectively configured as a first end wall and a second end wall. The stress cone is disposed inside the air cavity and connected to the second end wall. The stress cone has a plug-in channel communicating with the corresponding plug-in hole. The stress cone is disposed inside the air cavity, connected to the second end wall, and surrounds the corresponding plug-in hole. The peripheral side wall of the stress cone is spaced apart from the inner peripheral wall of the shell. The rain skirt protrudes from the outer side wall of the shell and surrounds the shell. Multiple rain skirts are provided, and the multiple rain skirts are arranged at intervals along the axial direction of the shell.

[0008] According to some embodiments of this application, the stress cone includes a first vertebral body, a second vertebral body, and a third vertebral body. The first vertebral body and the third vertebral body are respectively connected to both ends of the second vertebral body, and the first vertebral body is connected to the second end wall. The insertion channel is disposed through the first vertebral body, the second vertebral body, and the third vertebral body. The wall thickness of the first vertebral body gradually decreases from the end facing the second vertebral body to the end away from the second vertebral body, and the wall thickness of the third vertebral body gradually decreases from the end facing the second vertebral body to the end away from the second vertebral body.

[0009] According to some embodiments of this application, the housing includes a first annular portion, a second annular portion, and a third annular portion. The first annular portion and the third annular portion are respectively connected to the two ends of the second annular portion. The inner diameter of the first annular portion gradually decreases from the end facing the second annular portion to the end away from the second annular portion. The inner diameter of the third annular portion gradually decreases from the end facing the second annular portion to the end away from the second annular portion. The second annular portion at least partially overlaps the stress cone in the axial direction.

[0010] According to some embodiments of this application, the air supply unit further includes a first limiting member and a first sealing ring. The first limiting member is fixedly sleeved on the air supply pipe. The first end wall is provided with a first connecting channel. The air supply pipe passes through the first connecting channel and is threadedly connected to the first end wall. The first limiting member abuts against the first end wall. The first sealing ring is sandwiched between the first limiting member and the first end wall. And / or, the exhaust unit further includes a second limiting member and a second sealing ring. The second limiting member is fixedly sleeved on the exhaust pipe. The second end wall is provided with a second connecting channel. The air supply pipe passes through the second connecting channel and is threadedly connected to the second end wall. The second limiting member abuts against the second end wall. The second sealing ring is sandwiched between the second limiting member and the second end wall.

[0011] According to some embodiments of this application, the electronic control unit further includes an alarm element, which is electrically connected to the controller.

[0012] According to some embodiments of this application, the gas source is provided with an air inlet and an air outlet, the air outlet is connected to the air delivery pipe, and the air inlet is connected to the exhaust pipe.

[0013] The air pressure control method for cable terminals according to the second aspect of this application is applied to the cable terminals of the first aspect embodiment. The controller is preset with sequentially increasing replenishment air pressure values, warning air pressure values, rated working air pressure values, and safety air pressure values. The method includes the following steps: Gas is introduced into the air chamber in the terminal body through the gas supply unit; The real-time air pressure value of the air chamber is obtained by an air pressure sensor connected to the main body of the terminal. When the real-time air pressure value reaches the rated working air pressure value, the control air supply unit stops inputting gas; When the real-time air pressure value is equal to or lower than the warning air pressure value, the control alarm element sends a first alarm signal to the remote terminal. When the real-time air pressure value is equal to or lower than the replenishment air pressure value, the air delivery unit connected to the air chamber is controlled to replenish the air chamber with gas; When the real-time air pressure value is equal to or greater than the safe air pressure value, the exhaust unit connected to the air chamber is controlled to discharge the excess gas in the air chamber until the real-time air pressure value drops to the rated working air pressure value.

[0014] The air conditioner according to the embodiments of this application has at least the following beneficial effects: by preset sequentially increasing replenishment air pressure, warning air pressure, rated working air pressure, and safety air pressure, and based on the comparison results of the air pressure value fed back by the air pressure sensor in real time with each preset threshold, the controller automatically executes corresponding control actions, realizing fully automatic closed-loop management of the air chamber pressure of the cable terminal. When the air pressure drops to the warning air pressure value, the controller sends a prompt alarm to the remote terminal through the wireless communication module, so that maintenance personnel can know the terminal status in a timely manner without going to the site; when the air pressure continues to drop to the replenishment air pressure value, the controller automatically controls the air supply unit to replenish air, so that the air pressure is restored to the rated working air pressure value; when the air pressure exceeds the safety air pressure value, the controller automatically controls the exhaust unit to exhaust and release pressure, ensuring the safety of the terminal structure. This method can maintain the rated working pressure of the terminal without manual intervention, and maintenance personnel can obtain abnormal air pressure information through the remote terminal, without relying on manual on-site inspection.

[0015] According to some embodiments of this application, the rated working air pressure is defined as P0, the replenishing air pressure is defined as P1, the warning air pressure is defined as P2, and the safety air pressure is defined as P3, where P1=0.7P0, P2=0.8P0, and P3=1.15P0.

[0016] According to some embodiments of this application, the controller is further preset with a fault air pressure value, the fault air pressure value being less than the replenishment air pressure value, and the method further includes the following steps: when the real-time air pressure value is equal to or lower than the fault air pressure value, the control alarm element sends a second alarm signal to the remote terminal.

[0017] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0018] The present application will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a schematic diagram of the connection between a cable terminal and a cable according to one embodiment of this application; Figure 2 This is a cross-sectional view of a cable terminal according to an embodiment of this application; Figure 3 for Figure 2 Enlarged view of point A in the middle; Figure 4 for Figure 2 Enlarged view of point B in the middle; Figure 5 This is a circuit connection diagram of a cable terminal according to an embodiment of this application; Figure 6 This is a flowchart of a method for controlling the air pressure of a cable terminal according to this application.

[0019] Icon labels: 100. Cable terminal; 10. Terminal body; 11. Outer shell; 111. Air chamber; 112. First end wall; 113. Second end wall; 114. First annular portion; 115. Second annular portion; 116. Third annular portion; 12. Stress cone; 121. First cone; 122. Second cone; 123. Third cone; 124. Insertion channel; 13. Rain skirt; 14. Insertion hole; 21. Air source; 22. Air supply pipe; 23. First control valve; 24. First limiting member; 25. First sealing ring; 31. Exhaust pipe; 32. Second control valve; 33. Second limiting member; 34. Second sealing ring; 41. Pressure sensor; 200. Cable. Detailed Implementation

[0020] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0021] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, features defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0022] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0023] Cable terminations are used to achieve electrical connections and insulation protection at the ends of cables. Currently, power distribution lines widely use silicone rubber cold-shrink cable terminations, which rely on the elastic material itself to shrink and tightly grip the cable layers. However, over long-term operation, silicone rubber is affected by factors such as material aging and low-temperature environments, resulting in a continuous decrease in its shrinkage modulus and a gradual weakening of its gripping force. This leads to air gaps at the termination-to-cable interface, easily causing partial discharge and even insulation breakdown faults. Furthermore, once a cold-shrink cable termination suffers fatigue damage, no adjustment or repair can be made. When the gripping force decays to a critical value, the entire termination must be removed and replaced, resulting in long power outages and high maintenance costs.

[0024] In order to overcome the problems of irreversible loss of clamping force, inability to repair, and lack of monitoring of operating status caused by rubber aging and low temperature in traditional cold shrink terminals, this application proposes a cable terminal.

[0025] like Figure 1 , Figure 2 and Figure 5 As shown, the embodiment of the cable terminal proposed in this application includes a terminal body, an air supply unit, an exhaust unit, and an electrical control unit. The terminal body has an internal air chamber and two opposing end walls, each with a insertion hole for a cable to pass through. The air supply unit includes an air source, an air supply pipe, and a first control valve. One end of the air supply pipe is connected to the air source, and the other end passes through the first end wall to communicate with the air chamber. The first control valve is connected to the air supply pipe. The exhaust unit includes an exhaust pipe and a second control valve. One end of the exhaust pipe passes through the second end wall to communicate with the air chamber, and the second control valve is connected to the exhaust pipe. The electrical control unit includes a controller and a pressure sensor. The pressure sensor is connected to the terminal body and at least partially disposed in the air chamber for detecting the real-time air pressure. The pressure sensor, the first control valve, and the second control valve are electrically connected to the controller. The controller controls the opening or closing of the first and second control valves based on the air pressure value fed back by the pressure sensor. The controller has a wireless communication module, enabling it to send alarm signals to a remote terminal via the wireless communication module.

[0026] The terminal body is made of insulating material, such as epoxy resin or silicone rubber, to ensure sufficient strength and insulation performance. The terminal body has a first end wall and a second end wall, each with a insertion hole. These two insertion holes are coaxially aligned and communicate with an air cavity, allowing the cable to pass through axially. The cable enters the air cavity through the insertion hole in the first end wall and exits through the insertion hole in the second end wall, so that the terminal body is entirely fitted onto the outer wall of the cable end.

[0027] The gas supply unit, used to fill the gas chamber, includes a gas source, a gas supply pipe, and a first control valve. The gas source can be an externally mounted gas storage tank containing dry insulating gas, such as nitrogen, sulfur hexafluoride, or dried and filtered compressed air. The gas source has an outlet; one end of the gas supply pipe connects to the outlet, and the other end passes through a pre-reserved first connection channel in the first end wall, extending into the gas chamber, thus connecting the gas source and the gas chamber to form a gas delivery path. The first control valve is connected to the gas supply pipe and controls the opening and closing of the gas supply line. When the first control valve is open, gas from the gas source can flow into the gas chamber through the gas supply pipe; when the first control valve is closed, the gas supply line is cut off, and gas flow is blocked.

[0028] The exhaust unit is used to discharge gas from the gas chamber to achieve pressure relief maintenance or overpressure protection. It specifically includes an exhaust pipe and a second control valve. One end of the exhaust pipe passes through the second end wall, extending into the gas chamber through a pre-reserved second connection channel, thus communicating with the gas chamber. The other end of the exhaust pipe leads to the external environment or connects to a gas recovery device. The second control valve is connected to the exhaust pipe and is used to control the opening and closing of the exhaust pipe. When the second control valve is open, gas in the gas chamber can be discharged through the exhaust pipe; when the second control valve is closed, the exhaust pipe is cut off, and the gas chamber remains sealed.

[0029] The first control valve and the second solenoid valve can be solenoid valves, both electrically connected to the controller to receive electrical control signals from the controller and perform opening or closing actions. A pressure sensor is connected to the terminal body. Specifically, a sensor mounting hole is provided on the first or second end wall of the terminal body. The sensing end of the pressure sensor extends into the air chamber through this mounting hole, and the base of the pressure sensor is fixed to the outer wall of the terminal body by threads or a flange. The pressure sensor can be electrically connected to the controller via wired or wireless means. The pressure sensor is used to detect the gas pressure in the air chamber in real time and transmits the detected real-time pressure signal to the controller. The controller outputs switching control signals to the first and second control valves according to preset control logic.

[0030] Meanwhile, the controller has a wireless communication module, which is used to send alarm signals from the controller to a remote terminal. The remote terminal can be a mobile phone of maintenance personnel, a computer in the monitoring center, or a power distribution maintenance management platform. The wireless communication module can be a 4G module, a 5G module, or a Wi-Fi module, etc. Through the wireless communication module, the controller can proactively push alarm information to maintenance personnel when there is abnormal air pressure, allowing maintenance personnel to know the terminal's operating status without going to the site.

[0031] The working process of the cable terminal of this invention is as follows: After the terminal is installed, the controller first controls the opening of the first control valve, and the insulating gas in the gas source flows into the gas chamber through the gas supply pipe. As the gas is continuously filled, the gas pressure in the gas chamber gradually increases. The gas pressure sensor detects the gas pressure value in the gas chamber in real time and feeds back the gas pressure value to the controller in the form of an electrical signal. The controller compares the received real-time gas pressure value with the internally preset rated working gas pressure value. When the real-time gas pressure value reaches the rated working gas pressure value, the controller sends a closing command to the first control valve to stop the gas filling, and the cable terminal enters the rated working state. During long-term operation, if the gas pressure in the gas chamber drops due to aging of the seals or temperature changes, the gas pressure sensor detects the pressure drop and transmits the signal to the controller. The controller determines whether the real-time gas pressure value is lower than the preset replenishment gas pressure value. If it is lower than the preset replenishment gas pressure value, the controller controls the first control valve to open again and automatically replenishes the gas chamber until the gas pressure returns to the rated value and then stops replenishing the gas. Conversely, if the gas pressure in the gas chamber rises due to factors such as temperature rise, the gas pressure sensor detects the pressure rise and transmits the signal to the controller. The controller determines whether the real-time air pressure value is higher than the preset safe air pressure value. If it is higher than the safe air pressure value, it controls the second control valve to open and discharge excess gas through the exhaust pipe until the air pressure drops to the rated value and then closes the second control valve.

[0032] During the operation of the cable terminal, the controller communicates with a remote terminal via a wireless communication module. When the real-time air pressure value detected by the air pressure sensor is lower than the set warning air pressure value (e.g., 80% of the rated working air pressure value), the controller determines that the air chamber pressure has slightly decreased and immediately sends a first alarm signal to the remote terminal via the wireless communication module, such as a prompt signal of "low air pressure, inspection recommended". When the real-time air pressure value detected by the air pressure sensor continues to drop below the set fault air pressure value (e.g., 60% of the rated working air pressure value), the controller determines that the air chamber has a serious leak and immediately sends a second alarm signal to the remote terminal via the wireless communication module, such as a fault alarm of "terminal leakage, please handle urgently". Based on this technical solution, maintenance personnel can be aware of abnormal terminal operation status without going to the site and take corresponding measures according to the level of alarm signal, further improving the intelligent operation and maintenance level of cable terminals and avoiding insulation failures caused by undetected pressure abnormalities.

[0033] In summary, unlike traditional cold-shrink cable terminations that rely on the passive shrinkage of silicone rubber to provide clamping force, this technical solution actively applies and dynamically maintains the pressure in the air chamber by incorporating an air cavity within the termination body and configuring an electronic control system consisting of a controller, a pressure sensor, a first control valve, and a second control valve. Utilizing air pressure as a pressure source, a radial clamping force is continuously applied to the cable, ensuring stable clamping of the cable by the termination body. The controller automatically controls the opening and closing of the first and second control valves based on the air pressure values ​​fed back by the pressure sensor, achieving automatic air replenishment and repair when air pressure drops and automatic venting protection when pressure exceeds the limit, overcoming the problem of irreversible clamping force attenuation caused by rubber aging and low temperatures in traditional cold-shrink terminations. Simultaneously, the controller has a wireless communication module that can send alarm signals to remote terminals, allowing maintenance personnel to obtain terminal operating status information without going to the site, further improving the intelligent operation and maintenance level of cable terminations.

[0034] Reference Figure 2 In some embodiments, the terminal body includes a shell, a stress cone, and a rain skirt. An air cavity is disposed inside the shell, with the two ends of the shell respectively forming a first end wall and a second end wall. The stress cone is disposed inside the air cavity and connected to the second end wall. The stress cone has a connection channel communicating with a corresponding insertion hole. The stress cone is disposed inside the air cavity, connected to the second end wall, and surrounds the corresponding insertion hole. The peripheral sidewall of the stress cone is spaced apart from the inner peripheral wall of the shell. Multiple rain skirts protrude from the outer sidewall of the shell and surround the shell. These multiple rain skirts are arranged at intervals along the axial direction of the shell.

[0035] The internal cavity of the outer shell is the aforementioned air cavity, and the two ends of the outer shell form the first end wall and the second end wall, respectively. The stress cone is disposed inside the air cavity and fixedly connected to the inner side of the second end wall. The stress cone has an axially penetrating insertion channel, which is directly opposite and connected to the insertion hole on the second end wall. During installation, the cable enters through the insertion hole on the second end wall, passes through the insertion channel, and exits through the insertion hole on the first end wall. The stress cone is preferably made of a semi-conductive elastic material, such as semi-conductive silicone rubber. After assembly, the stress cone is fitted onto the cut end of the cable's shielding layer; its semi-conductive material can uniformly distribute the electric field and prevent electric field concentration.

[0036] The outer diameter of the stress cone is smaller than the inner diameter of the outer shell. The outer wall of the stress cone and the inner wall of the outer shell are spaced apart, forming an annular gap that constitutes part of the air chamber. Gas enters the air chamber through the gas supply pipe on the first end wall, filling the gap between the inner wall of the outer shell and the outer wall of the stress cone. The gas pressure acts evenly on the outer wall of the stress cone. This pressure is transmitted through the material of the stress cone to its inner wall, making the inner wall of the stress cone more tightly pressed against the cable layer, thereby enhancing the clamping force. When the set pressure is maintained in the air chamber, the radial pressure of the stress cone on the cable layer remains constant, unaffected by external temperature changes and material aging.

[0037] In theory, even without a stress cone inside the outer casing, radial compressive force can be applied to the cable layer through the air pressure within the air chamber. However, this compressive force is dispersed and uneven. This embodiment incorporates a stress cone inside the outer casing, fitted around the cable layer with its inner wall tightly fitted to the outer wall of the cable layer across the entire circumference, forming a clear and defined pressure transmission interface. The stress cone converts the fluid pressure, originally dispersed on the cable surface, into a radial clamping force uniformly distributed along the cable circumference, achieving concentrated application and uniform distribution of the clamping force, thereby ensuring stable clamping of the cable by the terminal body.

[0038] The rain skirt protrudes from the outer wall of the housing and surrounds the housing. Multiple rain skirts are provided and arranged at intervals along the axial direction of the housing. The rain skirts increase the creepage distance on the outer surface of the housing and improve the terminal's anti-flashover capability in outdoor humid and dirty environments.

[0039] Furthermore, referring to Figure 2 The stress cone comprises a first vertebral body, a second vertebral body, and a third vertebral body connected sequentially along the axial direction. The first vertebral body is connected to the second end wall, and an insertion channel is provided through the first vertebral body, the second vertebral body, and the third vertebral body. The wall thickness of the first vertebral body gradually decreases from the end facing the second vertebral body to the end away from the second vertebral body, and the wall thickness of the third vertebral body gradually decreases from the end facing the second vertebral body to the end away from the second vertebral body.

[0040] In other words, the first cone has a thicker wall at the end closer to the second end wall and a thinner wall at the end farther from the second end wall; similarly, the third cone has a thicker wall at the end closer to the second end wall and a thinner wall at the end farther from the second end wall. This gradual change in wall thickness between the first and third cones ensures good flexibility and fit at both ends of the stress cone, allowing it to adapt to minute diameter deviations in the cable layers, ensuring a gapless fit at the ends and eliminating electric field concentration at the ends.

[0041] When insulating gas is filled into the gas cavity, the gas pressure acts uniformly on the outer inclined surfaces of the first and third vertebrae, as well as the outer wall of the second vertebra. Since the first and third vertebrae are wedge-shaped, the external gas pressure applied to the inclined surfaces generates two components: one radially inward and the other axially towards the second vertebra. The radial component is directly transmitted through the stress cone material to the inner wall of the insertion channel, acting on the cable layer to form a clamping force; the axial component causes the stress cone to wed itself tightly towards the cable, further enhancing the interface contact.

[0042] Continue to refer to Figure 2 The outer shell includes a first annular portion, a second annular portion, and a third annular portion. The first and third annular portions are respectively connected to the two ends of the second annular portion. The inner diameter of the first annular portion gradually decreases from the end facing the second annular portion to the end away from the second annular portion, and the inner diameter of the third annular portion also gradually decreases from the end facing the second annular portion to the end away from the second annular portion. That is, the first and third annular portions are tapered cylindrical sections with gradually decreasing inner diameters, while the second annular portion is a straight cylindrical section. The second annular portion at least partially overlaps with the stress cone in the axial direction.

[0043] In this embodiment, the annular gap between the inner wall of the second annular portion and the outer wall of the cable layer is a region with a large radial space in the air cavity. The stress cone is a component that converts the fluid pressure dispersed on the cable surface into a radial clamping force uniformly distributed along the circumference of the cable. In this embodiment, the second annular portion is configured to overlap the stress cone at least partially in the axial direction, so that the air pressure can directly act on the outer wall of the stress cone in the axial region corresponding to the second annular portion. Due to the large radial space of the second annular portion, the annular gap between the outer wall of the stress cone and the inner wall of the second annular portion in this region is relatively spacious, resulting in a larger air pressure application area and a greater gas capacity. The outer wall of the stress cone can receive sufficient air pressure, which is then concentrated by the stress cone and converted into a uniform circumferential clamping force on the cable layer, resulting in a tighter clamping force.

[0044] Reference Figure 3 In some embodiments, the air supply unit further includes a first limiting member and a first sealing ring. The first limiting member is fixedly sleeved on the air supply pipe. The first end wall is provided with a first connecting channel. The air supply pipe passes through the first connecting channel and is threadedly connected to the first end wall. The first limiting member abuts against the first end wall. The first sealing ring is sandwiched between the first limiting member and the first end wall.

[0045] The first limiting member can be an integrally formed flange structure with the air supply pipe, or it can be independently formed and fixed to the outer wall of the air supply pipe by welding, bonding, or threaded connection. A first connecting channel, which is a threaded through hole, is provided on the first end wall. The outer wall of the air supply pipe has an external thread that matches the internal thread of the first connecting channel. The air supply pipe passes through the first connecting channel and is threadedly connected to the first end wall. When the air supply pipe is screwed into the first connecting channel to a predetermined position, the first limiting member abuts against the outer end face of the first end wall, serving as an axial limiting and locking mechanism. A first sealing ring is sandwiched between the first limiting member and the first end wall. The abutting and clamping force of the first limiting member causes the first sealing ring to elastically deform, filling the gap between the first limiting member and the first end wall, thus sealing the air inlet end.

[0046] Similarly, refer to Figure 4 The exhaust unit also includes a second limiting member and a second sealing ring. The second limiting member is fixedly sleeved on the exhaust pipe. The second end wall is provided with a second connecting channel. The air supply pipe passes through the second connecting channel and is threadedly connected to the second end wall. The second limiting member abuts against the second end wall. The second sealing ring is sandwiched between the second limiting member and the second end wall.

[0047] The second limiting member can be an integrally formed flange structure with the exhaust pipe, or it can be independently formed and fixed to the outer wall of the exhaust pipe by welding, bonding, or threaded connection. A second connecting channel, which is a threaded through hole, is provided on the second end wall. The outer wall of the exhaust pipe has an external thread that matches the internal thread of the second connecting channel. The exhaust pipe passes through the second connecting channel and is threadedly connected to the second end wall. When the exhaust pipe is screwed into the second connecting channel to a predetermined position, the second limiting member abuts against the outer end face of the second end wall, serving as an axial limiting and locking mechanism. A second sealing ring is sandwiched between the second limiting member and the second end wall. The abutting and clamping force of the second limiting member causes the second sealing ring to elastically deform, filling the gap between the second limiting member and the second end wall, thus sealing the exhaust end.

[0048] In some embodiments of this application, the electrical control unit further includes an alarm element, which is electrically connected to the controller. The alarm element may include an audible and visual alarm, such as a combination of a buzzer and a flashing light. The audible and visual alarm is installed on the control cabinet or terminal tower at the power distribution site. When an abnormal pressure occurs, the alarm element emits an audible and visual signal to alert on-site inspection personnel.

[0049] In some embodiments of this application, the gas source is provided with an inlet and an outlet. The outlet is connected to an air supply pipe for supplying gas to the gas chamber; the inlet is connected to an exhaust pipe for recovering the gas discharged from the gas chamber. This embodiment, by providing an inlet and an outlet on the gas source, connecting the outlet to the air supply pipe, and connecting the inlet to the exhaust pipe, forms a circulating gas path. This allows the discharged gas to be recovered back into the gas source for reuse, reducing gas consumption caused by frequent gas replenishment during long-term operation of the cable terminal.

[0050] Reference Figure 6 This application also proposes a method for controlling the air pressure of a cable terminal, comprising the following steps: S10: Gas is introduced into the air chamber in the terminal body through the gas supply unit; S20: Obtain the real-time air pressure value of the air chamber through the air pressure sensor connected to the main body of the terminal; S30: When the real-time air pressure value reaches the rated working air pressure value, control the air supply unit to stop inputting gas; S40: When the real-time air pressure value is equal to or lower than the warning air pressure value, the control alarm element sends a first alarm signal to the remote terminal; S50: When the real-time air pressure value is equal to or lower than the replenishment air pressure value, control the air delivery unit connected to the air chamber to replenish the air chamber with gas; S60: When the real-time air pressure value is equal to or greater than the safe air pressure value, control the exhaust unit connected to the air chamber to discharge the excess gas in the air chamber until the real-time air pressure value drops to the rated working air pressure value.

[0051] Specifically, this method is applied to the cable terminal mentioned above, which includes a terminal body, an air supply unit, an air exhaust unit, and an electronic control unit. The terminal body has an internal air chamber. The air supply unit is used to fill the air chamber with gas; the air exhaust unit is used to expel the gas from the air chamber to achieve pressure relief maintenance or overpressure protection. The electronic control unit includes a controller and a pressure sensor. The controller is preset with sequentially increasing replenishment pressure, warning pressure, rated working pressure, and safety pressure values. The pressure sensor is connected to the terminal body and at least partially disposed in the air chamber, used to detect the real-time pressure of the air chamber. The pressure sensor continuously collects pressure data within the air chamber at a set sampling frequency and transmits the detected real-time pressure signal to the controller. The sampling frequency can be set according to actual needs, for example, once per second or once per hundred milliseconds. The controller controls the opening or closing of a first control valve connected to the air inlet pipe and a second control valve connected to the air outlet pipe based on the pressure value fed back by the pressure sensor. Furthermore, the controller has a wireless communication module, which enables the controller to send alarm signals to a remote terminal.

[0052] After the terminal is installed, the controller opens the first control valve, allowing gas from the gas source to flow into the gas chamber through the gas supply pipe, causing the gas pressure inside the chamber to rise. The controller compares the received real-time gas pressure value with the internally preset rated working gas pressure value. When the real-time gas pressure value reaches the rated working gas pressure value, the controller sends a closing command to the first control valve, which closes, cutting off the gas supply pipe and stopping the inflation of the gas chamber. At this point, the cable terminal enters its rated operating state.

[0053] During the operation of the cable terminal, the air pressure sensor is always in monitoring mode, and the controller is always connected to the remote terminal via a wireless communication module. When the real-time air pressure value detected by the air pressure sensor is equal to or lower than the set warning air pressure value, the controller determines that the air chamber pressure has slightly decreased and immediately sends a first alarm signal to the remote terminal via the wireless communication module, such as a "low air pressure, inspection recommended" prompt signal, to remind maintenance personnel to arrange an inspection plan. During this stage, the controller does not initiate automatic air replenishment to avoid frequent air filling and defilling operations caused by normal temperature fluctuations. When the real-time air pressure value detected by the air pressure sensor is equal to or lower than the set air replenishment air pressure value, the controller determines that the air pressure has dropped to a level requiring active intervention, controls the first control valve to open, and the gas in the air source flows back into the air chamber through the air supply pipe to achieve automatic air replenishment. During the air replenishment process, the controller continuously monitors the real-time air pressure value. After the air pressure rises back to the rated working air pressure value, the controller controls the first control valve to close, stopping air replenishment. When the ambient temperature rises, the air pressure in the air chamber may gradually increase. When the real-time air pressure value detected by the air pressure sensor is equal to or greater than the set safe air pressure value, the controller controls the second control valve to open, and the gas in the air chamber is discharged through the exhaust pipe until the air pressure drops to the rated working air pressure value and then the second control valve is closed.

[0054] In summary, this cable terminal's air pressure control method achieves fully automated closed-loop management of the cable terminal's air chamber pressure by pre-setting sequentially increasing replenishment air pressure, warning air pressure, rated working air pressure, and safety air pressure. Based on the comparison between the real-time air pressure feedback from the air pressure sensor and each preset threshold, the controller automatically executes corresponding control actions. When the air pressure drops to the warning air pressure, the controller sends a warning alarm to the remote terminal via a wireless communication module, allowing maintenance personnel to be aware of the terminal's status without needing to go to the site. When the air pressure continues to drop to the replenishment air pressure, the controller automatically controls the air supply unit to replenish air, restoring the air pressure to the rated working air pressure. When the air pressure exceeds the safety air pressure, the controller automatically controls the exhaust unit to release pressure, ensuring the terminal's structural safety. This method maintains the terminal's rated working pressure without manual intervention, and maintenance personnel can obtain abnormal air pressure information remotely, eliminating the need for manual on-site inspections.

[0055] The rated working air pressure is defined as P0, the replenishing air pressure as P1, the warning air pressure as P2, and the safety air pressure as P3, where P1 = 0.7P0, P2 = 0.8P0, and P3 = 1.15P0.

[0056] The rated working air pressure value P0 is the target pressure value in the air chamber during normal operation of the cable terminal. The value of P0 is determined through calculation and testing based on the terminal's voltage level, structural dimensions, and required clamping force. The replenishment air pressure value P1 is set to 0.7P0, meaning that when the air pressure drops to 70% of the rated working air pressure value, the controller controls the air supply unit to start replenishing air. The warning air pressure value P2 is set to 0.8P0, meaning that when the air pressure drops to 80% of the rated working air pressure value, the controller controls the alarm element to issue the first alarm signal. The safety air pressure value P3 is set to 1.15P0, meaning that when the air pressure rises to 115% of the rated working air pressure value, the controller controls the exhaust unit to start exhausting air.

[0057] In some embodiments of this method, the controller further presets a fault pressure value, which is less than the make-up air pressure value. After step S50, the method further includes the following steps: S70: When the real-time air pressure value is equal to or lower than the fault air pressure value, the control alarm element sends a second alarm signal to the remote terminal.

[0058] The fault gas pressure value is defined as P4, for example, P4 = 0.6P0. When the gas pressure drops to the fault gas pressure value P4, the controller triggers a second alarm signal. During normal operation of the cable terminal, when the gas pressure in the air chamber drops due to temperature changes, the automatic gas replenishment function can replenish the gas in time to restore the gas pressure to the rated working gas pressure value. However, when the cable terminal experiences a significant leak, such as when the sealing ring is displaced or damaged, the gas replenishment rate cannot compensate for the leakage rate, and the gas pressure will continue to drop. When the gas pressure sensor detects that the real-time gas pressure value has dropped to the fault gas pressure value, the controller determines that a serious leak has occurred in the cable terminal, and the automatic gas replenishment can no longer maintain the normal working pressure. It then sends a second alarm signal to the remote terminal via the wireless communication module, such as an alarm signal like "Terminal leak, please handle urgently," prompting maintenance personnel to go to the site for inspection, find the leak point, and repair it.

[0059] This embodiment provides a final safety line for cable terminals by pre-setting a fault pressure value lower than the replenishment pressure value in the controller, and controlling the alarm element to issue an emergency fault alarm when the real-time pressure value is equal to or lower than the fault pressure value. When the automatic replenishment function cannot maintain the rated working pressure, the system can promptly notify maintenance personnel for emergency handling, avoiding insulation breakdown accidents caused by severe interface pressure deficiency, and further improving the safety operation guarantee level of the cable terminals.

[0060] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0061] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A cable terminal, characterized in that, include: The terminal body has an air cavity inside and has a first end wall and a second end wall opposite to each other. The first end wall and the second end wall are respectively provided with plug holes for cables to pass through. An air supply unit includes an air source, an air supply pipe, and a first control valve. One end of the air supply pipe is connected to the air source, and the other end passes through the first end wall to communicate with the air chamber. The first control valve is connected to the air supply pipe. An exhaust unit, comprising an exhaust pipe and a second control valve, wherein one end of the exhaust pipe passes through the second end wall to communicate with the air chamber, and the second control valve is connected to the exhaust pipe; The electronic control unit includes a controller and a pressure sensor. The pressure sensor is connected to the terminal body and is at least partially disposed in the air cavity. The pressure sensor, the first control valve, and the second control valve are electrically connected to the controller. The controller controls the opening or closing of the first control valve and the second control valve based on the pressure value fed back by the pressure sensor. The controller has a wireless communication module and can send alarm signals to a remote terminal through the wireless communication module.

2. The cable terminal according to claim 1, characterized in that, The terminal body includes: The outer shell has an air cavity disposed inside it, and the two ends of the outer shell are respectively configured as the first end wall and the second end wall; A stress cone is disposed inside the air cavity and connected to the second end wall. The stress cone has a plugging channel communicating with the corresponding plugging hole. The stress cone is disposed inside the air cavity, connected to the second end wall and surrounding the corresponding plugging hole. The peripheral sidewall of the stress cone is spaced apart from the inner peripheral wall of the outer shell. Rain skirt, the rain skirt protrudes from the outer side wall of the outer shell and surrounds the outer shell, and multiple rain skirts are provided, the multiple rain skirts are arranged at intervals along the axial direction of the outer shell.

3. The cable terminal according to claim 2, characterized in that, The stress cone includes a first vertebral body, a second vertebral body, and a third vertebral body. The first vertebral body and the third vertebral body are respectively connected to both ends of the second vertebral body, and the first vertebral body is connected to the second end wall. The insertion channel is provided through the first vertebral body, the second vertebral body, and the third vertebral body. The wall thickness of the first vertebral body gradually decreases from the end facing the second vertebral body to the end away from the second vertebral body, and the wall thickness of the third vertebral body gradually decreases from the end facing the second vertebral body to the end away from the second vertebral body.

4. The cable terminal according to claim 2, characterized in that, The outer casing includes a first annular portion, a second annular portion, and a third annular portion. The first annular portion and the third annular portion are respectively connected to the two ends of the second annular portion. The inner diameter of the first annular portion gradually decreases from the end facing the second annular portion to the end away from the second annular portion. The inner diameter of the third annular portion gradually decreases from the end facing the second annular portion to the end away from the second annular portion. The second annular portion at least partially overlaps the stress cone in the axial direction.

5. The cable terminal according to any one of claims 1 to 4, characterized in that, The air supply unit further includes a first limiting member and a first sealing ring. The first limiting member is fixedly sleeved on the air supply pipe. The first end wall is provided with a first connecting channel. The air supply pipe passes through the first connecting channel and is threadedly connected to the first end wall. The first limiting member abuts against the first end wall. The first sealing ring is sandwiched between the first limiting member and the first end wall. And / or, the exhaust unit further includes a second limiting member and a second sealing ring, the second limiting member being fixedly sleeved on the exhaust pipe, the second end wall being provided with a second connecting channel, the air supply pipe passing through the second connecting channel and being threadedly connected to the second end wall, the second limiting member abutting against the second end wall, and the second sealing ring being sandwiched between the second limiting member and the second end wall.

6. The cable terminal according to any one of claims 1 to 4, characterized in that, The electronic control unit also includes an alarm element, which is electrically connected to the controller.

7. The cable terminal according to any one of claims 1 to 4, characterized in that, The air source is provided with an air inlet and an air outlet. The air outlet is connected to the air supply pipe, and the air inlet is connected to the exhaust pipe.

8. A method for controlling the air pressure of a cable terminal, characterized in that, Applied to the cable terminal as described in any one of claims 1 to 7, the controller is preset with sequentially increasing replenishment air pressure value, warning air pressure value, rated working air pressure value, and safety air pressure value, and the method includes the following steps: Gas is introduced into the air chamber in the terminal body through the gas supply unit; The real-time air pressure value of the air chamber is obtained by an air pressure sensor connected to the main body of the terminal; When the real-time air pressure value reaches the rated working air pressure value, the control air supply unit stops inputting gas; When the real-time air pressure value is equal to or lower than the warning air pressure value, the control alarm element sends a first alarm signal to the remote terminal. When the real-time air pressure value is equal to or lower than the replenishment air pressure value, the air delivery unit connected to the air chamber is controlled to replenish the air chamber with gas; When the real-time air pressure value is equal to or greater than the safe air pressure value, the exhaust unit connected to the air chamber is controlled to discharge the excess gas in the air chamber until the real-time air pressure value drops to the rated working air pressure value.

9. The air pressure control method for cable terminals according to claim 8, characterized in that, The rated working air pressure is defined as P0, the replenishing air pressure as P1, the warning air pressure as P2, and the safety air pressure as P3, where P1 = 0.7P0, P2 = 0.8P0, and P3 = 1.15P0.

10. The air pressure control method for cable terminals according to claim 8, characterized in that, The controller is also preset with a fault air pressure value, which is less than the replenishment air pressure value. The method further includes the following steps: When the real-time air pressure value is equal to or lower than the fault air pressure value, the control alarm element sends a second alarm signal to the remote terminal.

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