Zero-flux direct current transformer

Abstract

The invention provides a zero-flux direct current transformer, and relates to the technical field of intelligent power grids. Comprising a mounting frame; the outer shell is fixedly connected to the mounting frame; the inner shell is detachably connected to the outer shell; the two sleeves are symmetrically distributed and detachably connected to the two sides of the inner shell correspondingly, and the sleeves are detachably connected with cover plates; the insulating tube is detachably connected in the inner shell; the two sealing shells are symmetrically distributed and fixedly connected to the two ends of the insulating tube respectively, the cover plate is detachably connected with a connecting cover, a storage cavity is formed in the connecting cover, and a rubber ring and an extrusion ring are slidably connected into the storage cavity. Through the combined action of the insulating tube and the sealing shell, the leaky position of insulating gas is changed, and meanwhile, when the pressure of the insulating gas is reduced, the extrusion ring is automatically triggered to move, the rubber ring is compressed to enhance the sealing performance to ensure the continuous and stable insulating environment, the short-circuit risk is reduced, and the operation safety is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of smart grid, and particularly relates to a zero-flux DC current transformer. BACKGROUND

[0002] The current transformer is a key device for current measurement, electric energy metering and relay protection in the power system, and the precision and reliability thereof directly affect the safe, stable and economic operation of the power grid. With the rapid development of the fields of DC power transmission and new energy power generation, the demand for high-precision measurement of large DC current is increasingly urgent. At present, gas insulated current transformers are mostly used in high-voltage and large-current occasions, and SF6 or environmentally friendly gas is used as the insulating medium to realize the miniaturization and high performance of the device. The zero-flux technology forces the core to approach the zero-flux state through closed-loop compensation, which can significantly improve the measurement precision and linearity, and has become the development direction of high-precision DC sensing.

[0003] However, the shell of the existing gas insulated current transformer has a large number of static sealing interfaces (such as flange connection surfaces) and dynamic sealing interfaces (such as gas charging valves and density relay interfaces), and the sealing of these parts usually depends on polymer materials such as sealant. In the long-term operation of the current transformer, the device continuously bears mechanical stress caused by internal gas pressure and temperature cycle changes and the aging effect of the external environment (such as ultraviolet rays, ozone and temperature difference), which causes the elastic failure, cracking and compression permanent deformation of the sealing material, thereby forming leakage points, resulting in the leakage of the insulating gas in the current transformer. After the leakage of the insulating gas, the gas density in the current transformer decreases, thereby causing the decrease of the insulation strength, and under the condition of overvoltage, internal discharge or surface flashover may also occur, causing the explosion of the device. SUMMARY

[0004] In order to overcome the shortcomings of the existing DC current transformer in the use process, the present application provides a zero-flux DC current transformer.

[0005] Technical scheme: A zero-flux DC current transformer, comprising: a mounting frame; an outer shell body fixed to the upper side of the mounting frame; an inner shell body detachably connected to the inside of the outer shell body, a plurality of detection coils being arranged between the inner shell body and the outer shell body; two sleeve pipes symmetrically distributed and detachably connected to the two sides of the inner shell body, the sleeve pipes being detachably connected with cover plates; an insulating pipe detachably connected to the inner shell body, a shielding shell symmetrically distributed and detachably connected to the insulating pipe and slidingly connected to the corresponding sleeve pipe being detachably connected to the insulating pipe, and a gas filling pipe passing through the corresponding shielding shell and the corresponding sleeve pipe being fixedly connected to the insulating pipe and in communication therewith; The sealing shell has two symmetrical sealing shells respectively fixed to two ends of the insulating tube and respectively matched with the cover plates, the cover plates are detachably connected with the connecting covers matched with the sealing shells, the connecting covers are fixed with the wire terminals, the two wire terminals are fixed with the conductor in the insulating tube, the connecting covers are provided with the storage cavities communicated with the sealing shells, the storage cavities are slidably connected with the rubber rings and the extrusion rings, and the extrusion rings are used for extruding the rubber rings.

[0006] In addition, it is particularly preferred that the minimum distance between the two shielding shells is D, the length of the inner shell body is d, and D is not less than d.

[0007] In addition, it is particularly preferred that the inner sides of the connecting cover and the sealing shell are provided with inclined annular surfaces with the same inclination direction, the inclined annular surface on the connecting cover is matched with the inclined annular surface on the corresponding sealing shell, and the diameters of the inclined annular surfaces on the two sides away from the inner shell body are greater than the diameters of the inclined annular surfaces on the two sides close to the inner shell body.

[0008] In addition, it is particularly preferred that the inner sides of the rubber rings and the outer sides of the extrusion rings are provided with inclined annular surfaces, the inclined annular surfaces on the two sides are matched, and the diameters of the inclined annular surfaces on the two sides away from the inner shell body are less than the diameters of the inclined annular surfaces on the two sides close to the inner shell body.

[0009] In addition, it is particularly preferred that the connecting cover is provided with a storage cavity, the connecting cover is provided with a first through hole communicated with the corresponding storage cavity, the first through hole is communicated with the corresponding sealing shell, the connecting cover is slidably connected with a limiting pin, the extrusion ring is provided with a blind hole, the limiting pin is located in the blind hole of the extrusion ring, the limiting pin is used for limiting the extrusion ring, the storage cavity is fixed with an elastic sheet, and the elastic sheet is fixed with the limiting pin.

[0010] In addition, it is particularly preferred that the elastic sheet is arc-shaped and used for changing the position of the limiting pin.

[0011] In addition, it is particularly preferred that the connecting cover is provided with a storage cavity, the connecting cover is provided with a first through hole communicated with the corresponding storage cavity, the first through hole is communicated with the corresponding sealing shell, the connecting cover is slidably connected with a limiting pin, the extrusion ring is provided with a blind hole, the limiting pin is located in the blind hole of the extrusion ring, the limiting pin is used for limiting the extrusion ring, the storage cavity is fixed with an elastic sheet, and the elastic sheet is fixed with the limiting pin. The sealing valve has two symmetrical sealing valves respectively fixed to the sides of the connecting cover away from the inner shell body, the connecting cover is provided with a connecting hole, the connecting hole is communicated with the corresponding storage cavity, and the connecting hole is communicated with the corresponding sealing valve.

[0012] In addition, it is particularly preferred that the connecting cover is provided with a second through hole, the second through hole is communicated with the corresponding storage cavity, the second through hole is communicated with the corresponding sealing shell, the second through hole is fixed with a connecting pipe, the connecting pipe is rotatably connected with a rotating block on the side away from the inner shell body, and the rotating block is provided with a flow hole.

[0013] In addition, it is particularly preferred that the inner diameter of the connecting pipe is equal to the diameter of the first through hole, and the diameter of the flow-through hole is smaller than the diameter of the connecting pipe.

[0014] In addition, it is particularly preferred that the insulating pipe is fixed and communicated with a communication shell away from the side of the gas feeding pipe, the communication shell is provided with a visual window, the communication shell passes through the corresponding shielding shell and the corresponding sleeve, a moving block is sealingly and limitingly connected in the communication shell, a positioning ring is fixedly connected in the communication shell, and a return spring is fixedly connected between the communication shell and the moving block.

[0015] Compared with the prior art, the present application has the following beneficial effects: 1. The present application changes the position of the leakable insulating gas through the cooperation of the insulating pipe and the sealing shell, and automatically triggers the movement of the extrusion ring to compress the rubber ring to enhance the sealing performance when the pressure of the insulating gas decreases, thereby ensuring the continuous stability of the insulating environment, reducing the risk of short circuit and ensuring the safety of operation.

[0016] 2. The storage cavity is designed as an independent air cavity which can be filled and exhausted through a valve, and through simple filling and exhausting operation, the mechanical performance of the system can be optimized according to different working stages, the balance between static stability and dynamic responsiveness is achieved, and the practicability and adaptability of the entire device are enhanced.

[0017] 3. Through the axial position change of the moving block, the pressure state of the invisible insulating gas inside is converted into a direct and clear visual signal, so that the sealing state and the gas inventory of the insulating pipe can be quickly judged by observation without the help of complex electronic sensors, and the intuitiveness and convenience of monitoring are greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a schematic view of the three-dimensional structure of the present application; Figure 2 is a sectional view of the three-dimensional structure of the mounting frame of the present application; Figure 3 is a sectional view of the three-dimensional structure of the outer shell of the present application; Figure 4 is a sectional view of the three-dimensional structure of the insulating pipe of the present application; Figure 5 is a schematic view of the three-dimensional structure of the rubber ring and the extrusion ring of the present application; Figure 6 is a schematic view of the three-dimensional structure of the limiting pin and the elastic sheet of the present application; Figure 7 is a schematic view of the three-dimensional structure of the sealing valve and the connecting hole of the present application; Figure 8 is a schematic view of the three-dimensional structure of the present application Figure 7 is an enlarged view of the three-dimensional structure at A in the present application; Figure 9 A perspective view of the communication shell of the present application.

[0019] In the figure: 1, mounting frame, 2, outer shell, 3, inner shell, 4, sleeve, 5, cover plate, 6, insulating tube, 61, shielding shell, 7, sealing shell, 8, connecting cover, 81, terminal, 9, storage cavity, 10, rubber ring, 101, extrusion ring, 102, storage cavity, 11, limit pin, 12, elastic sheet, 13, sealing valve, 14, connecting hole, 15, first through hole, 16, second through hole, 17, connecting tube, 18, rotating block, 19, flow-through hole, 20, communication shell, 21, moving block, 22, positioning ring, 23, return spring. DETAILED DESCRIPTION

[0020] In order to make the objects, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application with reference to specific embodiments and accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present application. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present application.

[0021] Embodiment 1 The present embodiment discloses a zero-flux DC current transformer, aiming to solve the problem that the insulation gas in the existing gas insulated current transformer is prone to leakage during use.

[0022] Please refer to Figures 1-6 The DC current transformer comprises a mounting frame 1, an outer shell 2 fixedly connected to the upper side of the mounting frame 1, an inner shell 3 detachably connected to the inside of the outer shell 2, a plurality of detection coils arranged between the inner shell 3 and the outer shell 2, two sleeves 4 symmetrically distributed and detachably connected to the two sides of the inner shell 3, a cover plate 5 detachably connected to the sleeve 4, an insulating tube 6 detachably connected to the inner shell 3, a shielding shell 61 symmetrically distributed and detachably connected to the insulating tube 6 and slidingly connected to the corresponding sleeve 4, an aeration pipe fixedly connected to the insulating tube 6 and passing through the corresponding shielding shell 61 and the corresponding sleeve 4, two sealing shells 7 symmetrically distributed and fixedly connected to the two ends of the insulating tube 6 and respectively abutting the corresponding cover plates 5, a connecting cover 8 detachably connected to the cover plate 5 and abutting the corresponding sealing shell 7, a terminal 81 fixedly connected to the connecting cover 8, a conductor fixedly connected to the two terminals 81 and located in the insulating tube 6, a storage cavity 9 arranged on the connecting cover 8 and communicating with the corresponding sealing shell 7, a rubber ring 10 and an extrusion ring 101 slidingly connected in the storage cavity 9, and the extrusion ring 101 is used for extruding the rubber ring 10.

[0023] In the above scheme, the outer shell 2 and the inner shell 3, the sleeve 4 and the inner shell 3, the cover plate 5 and the corresponding sleeve 4, and the connecting cover 8 and the corresponding cover plate 5 can be connected by bolts, and sealing pads can be provided between the above parts to improve the sealing between them; The specific number of detection coils can be selected by the staff, and the detection coils are used for detecting the conductor to be detected, and an insulation layer needs to be provided between the detection coils and the inner shell 3; The insulation tube 6 is used to fill high-voltage insulation gas, so that the insulation tube 6 presents an insulating environment, and the gas inlet pipe on the insulation tube 6 is located on the left side of the insulation tube 6, which is used to introduce insulation gas into the insulation tube 6; The connecting part of the connecting cover 8 and the sealing shell 7 and the connecting part of the cover plate 5 and the sealing shell 7 can be provided with a rubber layer for increasing the sealing effect; The position of the storage cavity 9 communicated with the corresponding sealing shell 7 is located on the side close to the inner shell 3; The storage cavity 9 is located on the part of the connecting cover 8 close to the inner shell 3, and the width of the storage cavity 9 on the horizontal plane is greater than the width of the rubber ring 10 on the horizontal plane; The extrusion ring 101 is located on the side close to the inner shell 3 in the storage cavity 9, and in the normal state, the extrusion ring 101 can only move away from the inner shell 3, and in the normal state, the gas pressure in the storage cavity 9 is normal atmospheric pressure.

[0024] Please refer to Figure 3 and Figure 4 , the minimum distance between the two shielding shells 61 is D, the length of the inner shell 3 is d, D is not less than d, which is used to reduce the influence of the shielding shell on the detection result and improve the final detection accuracy.

[0025] Please refer to Figure 5 , the inner side of the connecting cover 8 and the sealing shell 7 is provided with an inclined ring surface with the same inclination direction, the inclined ring surface on the connecting cover 8 is fitted with the inclined ring surface on the corresponding sealing shell 7, and the diameters of the inclined ring surfaces on the two sides away from the inner shell 3 are greater than the diameters of the inclined ring surfaces on the sides close to the inner shell 3, which is used to increase the contact area between the connecting cover 8 and the corresponding sealing shell 7, thereby increasing the sealing property.

[0026] Please refer to Figure 6 , the inner side of the rubber ring 10 and the outer side of the extrusion ring 101 are provided with inclined ring surfaces, the inclined ring surfaces on the two are fitted, and the diameters of the inclined ring surfaces on the two sides away from the inner shell 3 are smaller than the diameters of the inclined ring surfaces on the sides close to the inner shell 3, so that the extrusion ring 101 can extrude the corresponding rubber ring 10 during moving away from the inner shell 3, so that the rubber ring 10 is deformed, thereby improving the sealing effect between the connecting cover 8 and the corresponding sealing shell 7.

[0027] Please refer to Figure 6 and Figure 7The connecting cover 8 is provided with a storage cavity 102, the connecting cover 8 is provided with a first through hole 15 in communication with the corresponding storage cavity 102, the first through hole 15 is in communication with the corresponding sealing shell 7, the connecting cover 8 is slidingly connected with a limiting pin 11, a blind hole is arranged on the extrusion ring 101, the limiting pin 11 is located in the blind hole of the extrusion ring 101, the limiting pin 11 is used for limiting the extrusion ring 101, an elastic sheet 12 is fixedly connected in the storage cavity 102, the elastic sheet 12 is fixedly connected with the limiting pin 11, the elastic sheet 12 is arc-shaped and used for changing the position of the corresponding limiting pin 11.

[0028] In the above scheme, the projection of the storage cavity 102 on the connecting cover 8 is located in the projection of the storage cavity 9 on the connecting cover 8; the elastic sheet 12 is cut from a spherical shell, and the elastic sheet 12 is concave downward in the normal state, the state of the elastic sheet 12 in the figure is the state after deformation, and the position of the limiting pin 11 is also the position after movement; the limiting pin 11 is located below the blind hole of the corresponding extrusion ring 101 in the normal state; the first through hole 15 is located below the elastic sheet 12.

[0029] The specific working process of the above scheme is as follows: When it is needed to detect the current of the cable by using the mutual inductor, the workers install the device at the designated position, then connect the two wire terminals 81 with the cable to be detected, after the connection is completed, the existing gas injection device is used to inject the insulating gas into the insulating pipe 6 through the gas injection pipe on the insulating pipe 6, so that the insulating pipe 6 is in a high-voltage insulation state, and the current in the cable to be detected can move along the path of the left wire terminal 81→the conductor→the right wire terminal 81, in the moving process, the current in the conductor is detected by the detection coil, and the detection result is transmitted to the remote control terminal, so as to realize the detection of the cable to be detected, in the detection process, the insulating pipe 6 and the insulating gas in it together provide an insulating working environment for the conductor, so as to ensure the uniqueness and accuracy of the current moving path of the cable, and further improve the accuracy of the measurement result.

[0030] In the process of injecting the insulating gas into the insulating tube 6, the insulating gas flows into the two storage cavities 102 through the two first through holes 15, so that the gas pressure on the lower side of the two storage cavities 102 gradually increases, when the gas pressure on the lower side of the storage cavities 102 increases to be greater than the atmospheric pressure, the two elastic sheets 12 are deformed upward under the influence of the gas pressure, so that the elastic sheets 12 are protruded upward (in this process, the two elastic sheets 12 gradually accumulate force), and the corresponding limiting pins 11 are driven to move upward by the elastic sheets 12 in the process of deformation (in this process, the pressing ring 101 cannot move under the combined action of the force of the gas pressure in the corresponding storage cavity 9 and the friction between the pressing ring 101 and the corresponding rubber ring 10), so that the limiting pins 11 are inserted into the blind holes of the pressing ring 101, the pressing ring 101 is limited, and the pressing ring 101 cannot move, when the elastic sheets 12 are deformed to the limit state (the state in the figure is the limit state), the limiting pins 11 move upward to the limit position, at this time, the pressure of the insulating gas in the insulating tube 6 does not reach the threshold value, until the pressure of the insulating gas in the insulating tube 6 reaches the threshold value, the staff stops the external inflation device, and detects the cable to be detected according to the above operation.

[0031] In the process of detecting the cable, the connection parts of the inner shell 3 and the two sleeve pipes 4 and the connection parts of the sleeve pipes 4 and the corresponding cover plates 5 are shielded by the insulating tube 6 and the two sealing shells 7, so that the gas in the insulating tube 6 cannot leak outward through the two connection parts, at this time, the insulating gas in the insulating tube 6 can only leak outward through the gap between the sealing shell 7 and the corresponding connecting cover 8.

[0032] When the insulating gas leaks outward along the gap between the left sealing shell 7 and the left connecting cover 8, the pressure of the insulating gas in the insulating tube 6 gradually decreases, at this time, the pressure on the elastic sheet 12 synchronously decreases, when the pressure on the elastic sheet 12 decreases to be less than the elastic force of the elastic sheet 12, the elastic sheet 12 starts to reset under the action of the elastic force of the elastic sheet 12, so that the elastic sheet 12 is concave downward to reset, so that the limiting pin 11 starts to move downward, when the limiting pin 11 moves downward to separate from the pressing ring 101, the pressing ring 101 starts to move left under the extrusion of the insulating gas in the insulating tube 6, and extrudes the rubber ring 10 in the process of moving, so that the diameter of the rubber ring 10 increases, so as to further improve the sealing between the rubber ring 10 and the connecting cover 8, so that the insulating gas in the insulating tube 6 cannot continue to leak outward, so as to ensure that the detection coil can normally detect the conductor, ensure the accuracy of the detection result, reduce the risk of accidental short circuit when the insulating gas leaks, and ensure the safety of the staff.

[0033] Embodiment 2 On the basis of embodiment 1, please refer to Figure 6 and Figure 7Further comprising: two sealing valves 13, symmetrically distributed, respectively fixed on the side of the corresponding connecting cover 8 away from the inner shell 3, the connecting cover 8 is provided with a connecting hole 14, the connecting hole 14 is in communication with the corresponding storage cavity 9, and the connecting hole 14 is in communication with the corresponding sealing valve 13.

[0034] In the above scheme, the sealing valve 13 can be selected as an existing valve such as a ball valve, which is not shown in detail in the figure, and the communication position of the connecting hole 14 and the corresponding storage cavity 9 is located on the side of the corresponding extrusion ring 101 away from the inner shell 3. Before filling the insulating gas into the insulating tube 6, the staff can first fill the gas (any gas can be used) into the two storage cavities 9 through the two sealing valves 13, so as to increase the pressure in the two storage cavities 9, thereby increasing the stability of the position of the two extrusion rings 101 during the movement of the two limit pins 11; after stopping filling high-pressure gas into the insulating tube 6, the staff can also extract the gas in the two storage cavities 9, so that the two storage cavities 9 present a negative pressure working environment, thereby increasing the movement speed of the extrusion ring 101 when the insulating gas leaks, and further reducing the volume of the insulating gas leakage.

[0035] Embodiment 3 On the basis of embodiment 2, this embodiment continues to optimize a zero-flux DC current transformer.

[0036] Please refer to Figure 6 and Figure 8 , the connecting cover 8 is provided with a second through hole 16, the second through hole 16 is in communication with the corresponding storage cavity 102, the second through hole 16 is in communication with the corresponding sealing shell 7, the second through hole 16 is fixedly connected with a connecting pipe 17, the connecting pipe 17 is rotatably connected with a rotating block 18 away from the inner shell 3, and the rotating block 18 is provided with a flow-through hole 19.

[0037] In the above scheme, the second through hole 16 is located above the corresponding elastic sheet 12; under normal conditions, the rotating block 18 is in a vertical position under the action of its own gravity, and the corresponding connecting pipe 17 is shielded by the rotating block 18, thereby reducing the flow area of the two connecting pipes 17; in this embodiment, the shape of the elastic sheet 12 in the figure is its normal state, at this time the elastic sheet 12 has stored elastic potential energy, but cannot automatically reset.

[0038] Please refer to Figure 7 and Figure 8 , the inner diameter of the connecting pipe 17 is equal to the diameter of the first through hole 15, and the diameter of the flow-through hole 19 is smaller than the diameter of the connecting pipe 17.

[0039] The specific working process of the above scheme is as follows: In the process of filling the insulating gas into the insulating tube 6, the insulating gas flows into the two storage cavities 9 through the two first through holes 15 and the two second through holes 16, in the process, the insulating gas pushes the two rotating blocks 18 to rotate around the connection between the two rotating blocks 18 and the corresponding connecting tubes 17, so that the two rotating blocks 18 gradually reduce the shielding area of the corresponding connecting tubes 17, thereby accelerating the flow speed of the insulating gas to the upper part of the storage cavity 9, reducing the pressure difference between the upper and lower sides of the elastic sheet 12 in the flow process, and thereby maintaining the stability of the shape of the elastic sheet 12.

[0040] After stopping the injection of insulating gas into the insulating tube 6, the rotating block 18 is in a vertical state under the action of its own gravity. When the insulating gas in the insulating tube 6 leaks, the insulating gas in the two storage cavities 102 is simultaneously reduced as the insulating gas in the insulating tube 6 gradually decreases. In this process, the insulating gas on the lower side of the two elastic sheets 12 flows along the corresponding first through holes 15, and the insulating gas on the upper side of the two elastic sheets 12 flows along the corresponding through holes 19, so that the flow rate of the insulating gas on the upper side of the elastic sheet 12 is less than that of the insulating gas on the lower side. The pressure difference between the upper and lower sides of the elastic sheet 12 causes the elastic sheet 12 to deform (causing the elastic sheet 12 to sag downward) and simultaneously move the corresponding limit pin 11 by the elastic sheet 12 in the deformation process, so that the limit pin 11 loses contact with the corresponding extrusion ring 101. Subsequently, the extrusion ring 101 extrudes the corresponding rubber ring 10, causing the rubber ring 10 to deform and achieve further sealing.

[0041] Embodiment 4 On the basis of Embodiment 3, this embodiment continues to optimize a zero-flux DC current transformer, aiming to enable the staff to visually observe the change in the volume of the insulating gas therein.

[0042] Please refer to Figure 3 and Figure 9 , the insulating tube 6 is fixedly connected and communicated with a communication shell 20 away from the side of the insulating tube 6 to which the gas filling tube is connected. The communication shell 20 is provided with a visible window, the communication shell 20 penetrates through the corresponding shielding shell 61 and the corresponding sleeve 4, the communication shell 20 is sealingly and limitingly slidably connected with a moving block 21, the communication shell 20 is fixedly connected with a positioning ring 22, and the communication shell 20 and the moving block 21 are fixedly connected with a return spring 23.

[0043] In the above scheme, the communication shell 20 is located on the right side of the insulating tube 6, and the position of the moving block 21 can be observed through the visible window on the communication shell 20 during use; the moving block 21 can only move up and down along the communication shell 20; the positioning ring 22 is used to limit the lowest position of the moving block 21; and the return spring 23 is always in a force storage state.

[0044] The specific working process of the above scheme is as follows: In the process of injecting the insulation gas into the insulation tube 6, the pressure in the insulation tube 6 is gradually increased, when the pressure in the insulation tube 6 is increased to a first threshold value (the minimum pressure required when the reset spring 23 is compressed), the moving block 21 is moved upward against the elastic force of the reset spring 23, when the reset spring 23 is compressed to the limit state, the moving block 21 is moved upward to the limit position, at this time, the insulation gas pressure in the insulation tube 6 reaches a second threshold value (the maximum pressure that the insulation tube 6 can bear), then the worker no longer fills the insulation gas into the insulation tube 6.

[0045] In the process of detection, if the insulation gas in the insulation tube 6 leaks, the insulation gas pressure in the insulation tube 6 will gradually decrease, at this time, the moving block 21 will gradually move downward under the action of the reset spring 23, so that the worker can judge the volume of the insulation gas in the insulation tube 6 and the sealing condition of the insulation tube 6 by observing the position of the moving block 21, so as to supplement the insulation gas into the insulation tube 6 by the worker, and the worker can judge whether the device needs to be stopped for maintenance according to the moving speed of the moving block 21.

[0046] The above only describes the embodiments of the present application and is not used to limit the present application. Any equivalent replacement within the principles of the present application shall be included in the protection scope of the present application. The contents not described in detail in the present application belong to the prior art known by the technical personnel in the field.

Claims

1. A zero-flux DC current transformer, characterized in that, include: Mounting bracket (1); The outer casing (2) is fixed to the upper side of the mounting bracket (1); The inner shell (3) is detachably connected to the inside of the outer shell (2), and a plurality of detection coils are provided between the inner shell (3) and the outer shell (2); The sleeve (4) has two symmetrically distributed sleeves, which are detachably connected to both sides of the inner shell (3), and the sleeve (4) is detachably connected to a cover plate (5). An insulating tube (6) is detachably connected to the inner shell (3). A shielding shell (61) is symmetrically distributed and slidably connected to the corresponding sleeve (4) on the insulating tube (6). A gas filling tube is fixedly connected to and connected to the insulating tube (6) and passes through the corresponding shielding shell (61) and the corresponding sleeve (4). The sealing shell (7) has two symmetrically distributed shells, which are respectively fixed to the two ends of the insulating tube (6) and respectively attached to the cover plate (5). The cover plate (5) is detachably connected to the connecting cover (8) attached to the corresponding sealing shell (7). The connecting cover (8) is fixedly connected to the terminal (81). The two terminals (81) are jointly fixed to the conductor located in the insulating tube (6). The connecting cover (8) is provided with a storage cavity (9) communicating with the corresponding sealing shell (7). A rubber ring (10) and a compression ring (101) are slidably connected in the storage cavity (9). The compression ring (101) is used to compress the rubber ring (10).

2. A zero-flux DC current transformer according to claim 1, characterized in that, The minimum distance between the two shielding shells (61) is D, and the length of the inner shell (3) is d, where D is not less than d.

3. A zero-flux DC current transformer according to claim 1, characterized in that, The inner sides of the connecting cover (8) and the sealing shell (7) are provided with inclined annular surfaces with the same inclination direction. The inclined annular surface on the connecting cover (8) is in contact with the inclined annular surface on the corresponding sealing shell (7), and the diameter of the inclined annular surface on both of them away from the inner shell (3) is larger than the diameter on the side closer to the inner shell (3).

4. A zero-flux DC current transformer according to claim 1, characterized in that, The inner side of the rubber ring (10) and the outer side of the compression ring (101) are both provided with inclined ring surfaces. The inclined ring surfaces on the two are in contact, and the diameter of the inclined ring surface on the side away from the inner shell (3) is smaller than the diameter on the side closer to the inner shell (3).

5. A zero-flux DC current transformer according to claim 4, characterized in that, The connecting cover (8) is provided with a storage cavity (102). The connecting cover (8) is provided with a first through hole (15) communicating with the corresponding storage cavity (102). The first through hole (15) is communicating with the corresponding sealing shell (7). The connecting cover (8) is slidably connected with a limiting pin (11). The extrusion ring (101) is provided with a blind hole. The limiting pin (11) is located in the blind hole of the extrusion ring (101). The limiting pin (11) is used to limit the extrusion ring (101). An elastic sheet (12) is fixedly connected in the storage cavity (102). The elastic sheet (12) is fixedly connected to the limiting pin (11).

6. A zero-flux DC current transformer according to claim 5, characterized in that, The elastic sheet (12) is arc-shaped and is used to change the position of the corresponding limiting pin (11).

7. A zero-flux DC current transformer according to claim 5, characterized in that, Also includes: The sealing valve (13) has two symmetrically distributed valves, which are respectively fixed to the side of the corresponding connecting cover (8) away from the inner shell (3). The connecting cover (8) is provided with a connecting hole (14), which communicates with the corresponding storage cavity (9) and the corresponding sealing valve (13).

8. A zero-flux DC current transformer according to claim 7, characterized in that, The connecting cover (8) is provided with a second through hole (16), which is connected to the corresponding storage cavity (102) and the corresponding sealing shell (7). A connecting pipe (17) is fixedly connected inside the second through hole (16). A rotating block (18) is rotatably connected to the side of the connecting pipe (17) away from the inner shell (3). A flow hole (19) is provided on the rotating block (18).

9. A zero-flux DC current transformer according to claim 8, characterized in that, The inner diameter of the connecting pipe (17) is equal to the diameter of the first through hole (15), and the diameter of the flow hole (19) is smaller than the diameter of the connecting pipe (17).

10. A zero-flux DC current transformer according to claim 1, characterized in that, The insulating tube (6) is fixedly connected to and connected to a connecting shell (20) on the side away from the gas filling pipe. The connecting shell (20) is provided with a viewing window. The connecting shell (20) passes through the corresponding shielding shell (61) and the corresponding sleeve (4). A moving block (21) is sealed and slidably connected inside the connecting shell (20). A positioning ring (22) is fixedly connected inside the connecting shell (20). A return spring (23) is fixedly connected between the connecting shell (20) and the moving block (21).

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