Transformer bushing

Abstract

The utility model discloses a transformer bushing, and belongs to the field of power transmission and transformation accessories. The transformer bushing comprises a conducting rod, a composite insulation sleeve and a fixing pin, the conducting rod comprises an outer side section, a middle section and an inner side section which are sequentially arranged, the composite insulation sleeve is arranged on the outer side of the middle section in a sleeving mode, and an oil cavity with the outer side end sealed and the inner side end opened is formed between the wall of a bushing hole of the composite insulation sleeve and the outer wall of the middle section. The fixing pin is arranged between the composite insulation sleeve and the conducting rod in a penetrating mode and used for limiting relative rotation of the conducting rod and the composite insulation sleeve. According to the utility model, the problem that the connection stability and reliability of inner and outer leads are affected by the rotation of the conducting rod is effectively solved; the locking stability of the fastener and the threaded section is improved, the heat dissipation effect of the sleeve is guaranteed, the overall service life of the sleeve is prolonged, and the heat stability of the sleeve is improved; the contact area of the inner side wire holder and the transformer lead wiring terminal is increased, the current-carrying capability of the connection part is improved, and the local heating phenomenon is effectively reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of transformer accessories more specifically, relate to a transformer bushing. BACKGROUND

[0002] The transformer bushing is the main insulation device outside the transformer box, and the outgoing line of the transformer winding must pass through the insulation bushing, so that the outgoing lines are insulated from each other and from the transformer shell, and the outgoing lines are also fixed. During the operation of the transformer, the transformer bushing plays a role in carrying current, and long-term load current passes through it, so it has high requirements for its electrical strength, mechanical strength and thermal stability.

[0003] The low-voltage side bushing of the transformer generally adopts a dry bushing, which is mainly composed of a conductive rod, an insulation sleeve, a sealing element and a fastener, and the material of the insulation sleeve mainly includes ceramic and composite material. The manufacturing cycle of the composite insulation sleeve is shorter than that of the ceramic insulation sleeve, so in recent years, more and more transformer bushings using composite insulation sleeves instead of ceramic insulation sleeves have appeared. However, the composite insulation sleeve has the following disadvantages: the heat generated by the conductive rod during the operation of the transformer acts on the composite insulation sleeve, and the composite insulation sleeve is prone to aging and cracking under the alternating cold and hot environment, which may cause oil leakage of the bushing and reduce the overall service life of the bushing.

[0004] Currently, there are also composite insulation sleeve bushings designed as oil-filled bushings. The oil cavity is formed inside the insulation sleeve by using a flat conductive rod, and the transformer oil inside the bushing is used to improve the heat dissipation efficiency inside the bushing and reduce the operating temperature of the bushing. However, this type of bushing has the following problems in actual application:

[0005] (1) The conductive rod is sleeved inside the composite insulation sleeve, and the assembly structure is used between the two. Although the composite insulation sleeve is fixed on the transformer shell by the pressing plate after the bushing is installed, the conductive rod is only locked on the insulation sleeve by the nut, and it is found in actual use that the conductive rod is prone to rotation under the action of external force, which may affect the stability and reliability of the connection between the inner and outer leads;

[0006] (2) The lower end of the conductive rod is flat in cross-section to form an oil cavity, which makes the thread of the fastener (nut) and the conductive rod incomplete, and may reduce the locking firmness and reliability of the fastener;

[0007] (3) The lower end (inner side end) of the conductive rod is directly connected to the lead by punching a hole in the flat section. Although the structure is simple and easy to manufacture, the width of the lower end of the conductive rod is small, and it is found in actual use that the contact area with the lead terminal is small, which may cause local heating at the connection position. In order to increase the effective contact area, the length of the lower end of the conductive rod is often longer, which may also increase the length of the transformer lead terminal, increase the manufacturing cost and the difficulty of installation for workers, and is not conducive to the optimization of the compactness of the transformer box. SUMMARY

[0008] 1. Technical problems solved by the utility model

[0009] One purpose of the utility model is to overcome the above-mentioned deficiency of easy rotation of the electrically conductive rod of the existing transformer bushing, and provide a transformer bushing, which adopts the technical scheme of the utility model, sets a fixing pin between the composite insulating sleeve and the electrically conductive rod, so that the electrically conductive rod and the insulating sleeve cannot rotate relative to each other, thereby effectively solving the problem of affecting the connection stability and reliability of the inner and outer lead wires due to the rotation of the electrically conductive rod; and the fixing pin can also fix the composite insulating sleeve and the electrically conductive rod, and can still ensure the effective sealing of the bushing when the fastener is loose, thereby improving the sealing reliability of the transformer bushing.

[0010] Another purpose of the utility model is to solve the problem of poor locking firmness and reliability of the fastener and the flat cross-section electrically conductive rod of the existing transformer bushing, the electrically conductive rod is designed in a circular cross-section threaded section, so that the fastener and the threaded section can be connected by complete threads, thereby improving the locking stability of the fastener and the threaded section and effectively preventing the fastener from loosening; at the same time, the oil inlet and outlet of the oil cavity inside the bushing is realized by the oil channel or oil hole arranged at the inner end of the composite insulating sleeve, thereby ensuring the heat dissipation effect of the bushing and improving the overall service life and thermal stability of the bushing.

[0011] Still another purpose of the utility model is to solve the problem of small contact area of the inner terminal block of the existing bushing and the transformer lead wire terminal and easy local heating, after the fastener is screwed onto the threaded section, the inner section in the initial state is flattened to form an inner terminal block, the width L2 of the flattened inner terminal block is greater than the outer diameter D1 of the threaded section and less than the outer diameter D2 of the inner end of the composite insulating sleeve, thereby increasing the contact area of the inner terminal block and the transformer lead wire terminal, improving the current carrying capacity of the connection, and effectively reducing the local heating phenomenon; and the size of the inner terminal block is shortened and widened, the worker is more convenient to install, the electrical distance is increased and the safety is better, the space occupied by the transformer can be reduced, which is beneficial to the subsequent transformer design optimization and reduces the manufacturing cost of the transformer; at the same time, the flattened inner terminal block can play a retreat-preventing role on the fastener, so that the fastener is never loose, thereby ensuring the long-term effective sealing of the bushing.

[0012] 2. Technical scheme

[0013] To achieve the above-mentioned purpose, the utility model provides a technical scheme as follows:

[0014] The utility model discloses a transformer bushing, including electrically conductive pole and composite insulation sleeve, electrically conductive pole includes the outside section, middle section and inside section that set gradually, the composite insulation sleeve is set in the outside of middle section, and the oil cavity of outside end sealing, inside end opening is formed between the sleeve hole hole wall of composite insulation sleeve and the outer wall of middle section, still include fixed pin, the fixed pin is set between composite insulation sleeve and electrically conductive pole, to limit the relative rotation of electrically conductive pole and composite insulation sleeve.

[0015] Further, the electrically conductive rod is provided with a first pin hole, the composite insulation sleeve is provided with a second pin hole opposite to the first pin hole, one end of the fixed pin is provided with an end cap, and the other end is provided with an expansion chuck, the expansion chuck of the fixed pin is inserted from the second pin hole on one side of the composite insulation sleeve, and then passes through the first pin hole and is inserted from the second pin hole on the other side.

[0016] Further, the cross-sectional shape of the middle section is non-circular, the sleeve hole of the composite insulation sleeve is a circular hole, and the oil cavity is enclosed by the circular sleeve hole and the non-circular middle section.

[0017] Further, the middle section is further provided with a plurality of oil guide holes penetrating the oil cavity on both sides.

[0018] Further, a sealing table is arranged between the outside section and the middle section, a threaded section is arranged between the middle section and the inside section, the outer end face of the composite insulation sleeve and the sealing table are sealingly connected through a sealing pad, a fastener is arranged on the threaded section, and the fastener is locked on the inner end face of the composite insulation sleeve.

[0019] Further, the cross-sectional shape of the threaded section is circular.

[0020] Further, a plurality of oil inlet and outlet holes are arranged on the threaded section and communicated with the oil cavity.

[0021] Further, the initial width L1 of the inside section is less than the outer diameter D1 of the threaded section, after the fastener is screwed on the threaded section, the inside terminal is formed by flattening the initial state of the inside section, the width L2 of the flattened inside terminal is greater than the outer diameter D1 of the threaded section and less than the outer diameter D2 of the inner end of the composite insulation sleeve.

[0022] Further, the inner end of the composite insulation sleeve is provided with a plurality of oil grooves and / or oil holes, the oil grooves are arranged on the inner end face of the composite insulation sleeve and communicated with the oil cavity, and the oil holes are arranged on the inner end side wall of the composite insulation sleeve and communicated with the oil cavity.

[0023] Further, the outer side of the composite insulation sleeve is further provided with a flange for being mounted on the transformer shell through a pressing plate, the transformer shell is fixed with a mounting rack, the pressing plate is mounted on the mounting rack through a locking member and is pressed on the flange, a sealing member is arranged between the bottom of the flange and the transformer shell, and the oil cavity is communicated with the inside of the transformer shell through the inner side end opening.

[0024] 3. Beneficial effects

[0025] Compared with the prior art, the technical scheme has the following beneficial effects:

[0026] (1) The transformer sleeve of the utility model, which comprises a conductive rod, a composite insulation sleeve and a fixing pin, the conductive rod comprises an outer side section, an intermediate section and an inner side section arranged in sequence, the composite insulation sleeve is sleeved on the outer side of the intermediate section, an oil cavity with an outer side end seal and an inner side end opening is formed between the sleeve hole wall of the composite insulation sleeve and the outer wall of the intermediate section, and the fixing pin is arranged between the composite insulation sleeve and the conductive rod to limit the relative rotation of the conductive rod and the composite insulation sleeve, so that the relative rotation between the conductive rod and the insulation sleeve is prevented, the connection stability and reliability of the inner and outer lead wires are effectively improved, the fixing pin can also fix the composite insulation sleeve and the conductive rod, the effective sealing of the sleeve is ensured when the fastener is loose, and the sealing reliability of the transformer sleeve is improved.

[0027] (2) The transformer sleeve of the utility model, one end of the fixing pin is provided with an end cap, the other end is provided with an expansion chuck, the expansion chuck of the fixing pin is arranged in the second pin hole on one side of the composite insulation sleeve, passes through the first pin hole and then is arranged out of the second pin hole on the other side, the fixing pin is convenient to install, the expansion chuck can prevent the fixing pin from loosening, and the installation is stable and reliable.

[0028] (3) The transformer sleeve of the utility model, the cross section shape of the intermediate section is non-circular, the sleeve hole of the composite insulation sleeve is a circular hole, and the oil cavity is enclosed by the circular sleeve hole and the non-circular intermediate section, the setting of the oil cavity is facilitated under the condition of ensuring the current-carrying area of the intermediate section, and the manufacturing of the insulation sleeve and the assembly with the conductive rod are facilitated.

[0029] (4) The transformer sleeve of the utility model, a plurality of oil guide holes penetrating through the oil cavity on both sides are arranged on the intermediate section, which is beneficial to the convection of the transformer oil in the oil cavity and accelerates the heat dissipation of the conductive rod and the whole sleeve.

[0030] (5) A transformer bushing of the present invention has a sealing platform between its outer section and the middle section, a threaded section between the middle section and the inner section, a sealing gasket is provided between the outer end face of the composite insulating sleeve and the sealing platform, a fastener is provided on the threaded section, and the fastener is locked on the inner end face of the composite insulating sleeve, and the cross-section of the threaded section is circular. The threaded section with a circular cross-section is designed so that the fastener and the threaded section can be connected by a complete thread, thereby improving the locking stability of the fastener and the threaded section and effectively preventing the fastener from loosening;

[0031] (6) A transformer bushing of the utility model has a plurality of oil grooves and / or oil holes provided on the inner end of the composite insulating sleeve, thereby ensuring the heat dissipation effect of the bushing and improving the overall service life and thermal stability of the bushing;

[0032] (7) A transformer bushing of the utility model is provided with a plurality of oil inlet and outlet holes on its threaded section, which are connected to the oil cavity, thereby improving the oil inlet and outlet effect at the bottom of the bushing and facilitating the flow of transformer oil inside the bushing;

[0033] (8) The utility model provides a transformer bushing, wherein the initial width L1 of the inner section is smaller than the outer diameter D1 of the threaded section. After the fastener is screwed onto the threaded section, the inner section in the initial state is flattened to form an inner terminal block. The width L2 of the inner terminal block formed by flattening is larger than the outer diameter D1 of the threaded section and smaller than the outer diameter D2 of the inner end of the composite insulating sleeve. With this design, the contact area between the inner terminal block and the transformer lead terminal is increased, the current carrying capacity of the connection is improved, and the local heating phenomenon is effectively reduced. In addition, the size of the inner terminal block is shortened and widened, which makes it more convenient for workers to install, can reduce the space occupied by the transformer, is beneficial to the subsequent transformer design optimization, and reduces the transformer manufacturing cost. At the same time, the flattened inner terminal block can play a role in stopping the fastener from retreating, so that the fastener will never loosen, ensuring the long-term effective sealing of the bushing. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of the overall structure of a transformer bushing of the present utility model;

[0035] Figure 2 for Figure 1 Schematic diagram of the cross-sectional structure in the AA direction;

[0036] Figure 3 for Figure 2 Schematic diagram of the cross-sectional structure in the middle BB direction;

[0037] Figure 4 This is a front structural diagram of the conductive rod in the present invention (initial state of the inner section);

[0038] Figure 5It is the side structure schematic view of the electrically-conductive rod (the initial state of the inner side section) in the utility model.

[0039] Figure 6 It is the front structure schematic view of the electrically-conductive rod (the flattened state of the inner side section) in the utility model.

[0040] Figure 7 It is the side structure schematic view of the electrically-conductive rod (the flattened state of the inner side section) in the utility model.

[0041] Figure 8 It is the structure schematic view of the composite insulation sleeve in the utility model.

[0042] Figure 9 It is the structure schematic view of the fixed pin in the utility model.

[0043] Figure 10 It is the installation structure schematic view of the transformer bushing in the utility model.

[0044] The label explanation in the schematic view is as follows:

[0045] 1, electrically-conductive rod; 1-1, outer side section; 1-1a, outer side wiring hole; 1-2, middle section; 1-2a, oil guide hole; 1-2b, plane; 1-2c, first pin hole; 1-3, inner side section; 1-3a, inner side wiring hole; 1-4, sealing platform; 1-5, threaded section; 1-5a, oil inlet and outlet hole; 2, composite insulation sleeve; 2a, sleeve hole; 2-1, flange; 2-2, oil passage; 2-3, oil passage hole; 2-4, second pin hole; 3, sealing gasket; 4, fastener; 5, fixed pin; 5-1, end cap; 5-2, expansion chuck; 6, oil cavity; 7, transformer shell; 7-1, mounting frame; 8, pressing plate; 9, locking piece. DETAILED DESCRIPTION

[0046] In order to further understand the content of the utility model, the utility model is described in detail in combination with the drawings and examples.

[0047] [Example 1]

[0048] As Figure 1 and Figure 2As shown, the transformer bushing of the embodiment comprises a conductive rod 1 and a composite insulating sleeve 2, the conductive rod 1 comprises an outer section 1-1, an intermediate section 1-2 and an inner section 1-3 arranged in sequence, the outer section 1-1, the intermediate section 1-2 and the inner section 1-3 are an integral structure, the composite insulating sleeve 2 is sleeved on the outer side of the intermediate section 1-2, and an oil cavity 6 with an outer end sealed and an inner end open is formed between the hole wall of the sleeve hole 2a of the composite insulating sleeve 2 and the outer wall of the intermediate section 1-2, so that the transformer oil can enter the oil cavity 6 from the inner end opening of the bushing, and the bushing has a heat dissipation and cooling effect, the outer section 1-1 and the inner section 1-3 respectively extend out of the composite insulating sleeve 2 for connecting the inner and outer leads of the transformer. The "outer end" above refers to the part of the transformer bushing located on the outside of the transformer shell; correspondingly, the "inner end" refers to the part of the transformer bushing located on the inside of the transformer shell. Compared with the existing transformer bushing, the transformer bushing of the embodiment further comprises a fixing pin 5, the fixing pin 5 is arranged between the composite insulating sleeve 2 and the conductive rod 1 to limit the relative rotation of the conductive rod 1 and the composite insulating sleeve 2. The fixing pin 5 is preferably made of insulating material. By arranging the fixing pin 5 between the composite insulating sleeve 2 and the conductive rod 1, the conductive rod 1 and the insulating sleeve cannot rotate relative to each other, and since the insulating sleeve is fixed after the bushing is installed, the problem of affecting the stability and reliability of the connection of the inner and outer leads due to the rotation of the conductive rod 1 is effectively solved; and the fixing pin 5 can also fix the composite insulating sleeve 2 and the conductive rod 1, and can still ensure the effective sealing of the bushing when the fastener is loose, thereby improving the sealing reliability of the transformer bushing.

[0049] The fixing pin 5 above can pass through the composite insulating sleeve 2 radially as a whole, or can pass through the composite insulating sleeve 2 on one side and be inserted into the conductive rod 1, and only needs to pin the conductive rod 1 and the composite insulating sleeve 2 to prevent relative rotation. The fixing pin 5 can be located at the outer end of the composite insulating sleeve 2, or can be located at the inner end of the composite insulating sleeve 2, that is, the fixing pin 5 can be located on the outside of the transformer shell, or can be located on the inside of the transformer shell. Of course, the fixing pin 5 is preferably arranged at the inner end of the composite insulating sleeve 2 to be hidden inside the transformer. Referring to Figure 2 and Figure 9 As shown, specifically in the embodiment, the conductive rod 1 is provided with a first pin hole 1-2c (as shown in Figures 4 to 7 ), and the composite insulating sleeve 2 is provided with a second pin hole 2-4 opposite to the first pin hole 1-2c (as shown in Figure 8), one end of the fixing pin 5 is provided with an end cap 5-1, and the other end is provided with an expansion chuck 5-2, the expansion chuck 5-2 of the fixing pin 5 is inserted from the second pin hole 2-4 on one side of the composite insulation sleeve 2, and then passes through the first pin hole 1-2c and then passes out from the second pin hole 2-4 on the other side. The size of the end cap 5-1 and the expansion chuck 5-2 of the fixing pin 5 is larger than the hole diameter of each pin hole, the expansion chuck 5-2 can pass through each pin hole after shrinking, and can automatically expand after passing out, so that the fixing pin 5 is fixed on the composite insulation sleeve 2. The fixing pin 5 is easy to install, the expansion chuck 5-2 can prevent the fixing pin 5 from loosening, and the installation is stable and reliable.

[0050] The size of the intermediate section 1-2 is smaller than the size of the sleeve hole 2a of the composite insulation sleeve 2, so that the corresponding oil cavity 6 is formed. In order to ensure the current-carrying area of the intermediate section 1-2, in this embodiment, the cross-sectional shape of the intermediate section 1-2 is non-circular, and the sleeve hole 2a of the composite insulation sleeve 2 is a circular hole, and the oil cavity 6 is enclosed by the circular sleeve hole 2a and the non-circular intermediate section 1-2. Under the condition of ensuring the current-carrying area of the intermediate section 1-2, the setting of the oil cavity 6 is facilitated, and the manufacturing of the insulation sleeve and the assembly with the conductive rod 1 are facilitated. Specifically, the intermediate section 1-2 can adopt a flat structure (as shown in Figure 3 The width direction size of the intermediate section 1-2 is slightly smaller than the hole diameter of the sleeve hole 2a, and two opposite oil cavities 6 are formed between the two side planes 1-2b and the sleeve hole 2a. Of course, the intermediate section 1-2 can also adopt other cross-sectional shapes, for example, the plane 1-2b part can also be a groove structure. In addition, referring to Figure 1 and Figure 2 As shown in the drawings, a plurality of oil guide holes 1-2a passing through the oil cavities 6 on both sides are also provided on the intermediate section 1-2, which is beneficial to the convection of transformer oil in the oil cavity 6 and accelerates the heat dissipation of the conductive rod 1 and the entire bushing.

[0051] Similar to the prior art, the composite insulation sleeve 2 in this embodiment can be made of existing electrical insulation composite materials, such as epoxy resin or DMC composite material or SMC composite material, which has excellent electrical properties and mechanical properties.

[0052] [Embodiment 2]

[0053] The basic structure and working principle of the transformer bushing of this embodiment are the same as those of embodiment 1, and the difference is that:

[0054] As shown in the drawings, Figure 1 and Figure 2As shown, in the embodiment, a sealing platform 1-4 is arranged between the outer segment 1-1 and the middle segment 1-2, and a threaded segment 1-5 is arranged between the middle segment 1-2 and the inner segment 1-3. The sealing platform 1-4 can be a circular platform structure with a diameter corresponding to the outer diameter of the outer end of the composite insulation sleeve 2. The outer end surface of the composite insulation sleeve 2 is sealed and matched with the sealing platform 1-4 through a sealing gasket 3. Specifically, a mounting groove can be arranged on the lower end surface of the sealing platform 1-4, and the sealing gasket 3 is arranged in the mounting groove. The outer side of the threaded segment 1-5 is provided with external threads, and the threaded segment 1-5 is provided with a fastener 4. The fastener 4 is locked on the inner end surface of the composite insulation sleeve 2, so that the sealing gasket 3 is tightly sealed. The fastener 4 can be a nut, which is screwed on the outer side of the threaded segment 1-5 to tightly fix the composite insulation sleeve 2. Since the fixing pin 5 can fix the conductive rod 1 and the composite insulation sleeve 2 to ensure that the sealing gasket 3 is tightly compressed, the locking of the fastener 4 can have a double fixing effect.

[0055] As shown in Figure 3 In the embodiment, the cross-sectional shape of the threaded segment 1-5 is circular, and the external threads thereon are complete, so that the fastener 4 and the threaded segment 1-5 can be connected by complete threads, improving the locking stability of the fastener 4 and the threaded segment 1-5 and effectively preventing the fastener 4 from loosening. Further, in order to facilitate the inflow and outflow of oil from the bottom of the bushing, a plurality of oil inlet and outlet holes 1-5a are arranged on the threaded segment 1-5 and are in communication with the oil cavity 6. The oil inlet and outlet holes 1-5a can be machined from the end of the threaded segment 1-5 without damaging the threaded structure, improving the oil inflow and outflow effect of the bottom of the bushing and facilitating the flow of transformer oil in the bushing.

[0056] [Embodiment 3]

[0057] The transformer bushing of the embodiment has the same basic structure and working principle as those of Embodiment 1 or Embodiment 2, and the difference lies in that:

[0058] As shown in Figure 1 and Figure 2 and Figure 8As shown, in the present embodiment, the inner end of the composite insulating sleeve 2 is provided with a plurality of oil grooves 2-2 and / or oil holes 2-3, wherein the oil grooves 2-2 are arranged on the end face of the inner end of the composite insulating sleeve 2 and communicate with the oil cavity 6; the oil holes 2-3 are arranged on the side wall of the inner end of the composite insulating sleeve 2 and communicate with the oil cavity 6. The oil grooves 2-2 or the oil holes 2-3 arranged on the inner end of the composite insulating sleeve 2 are used to realize the oil inlet and outlet of the oil cavity inside the bushing, which ensures the heat dissipation effect of the bushing and improves the overall service life and thermal stability of the bushing. The shape and number of the oil grooves 2-2 and the oil holes 2-3 can be set as needed. After the fastener 4 is locked on the end face of the inner end of the composite insulating sleeve 2, the oil grooves 2-2 and the fastener 4 can form a lateral opening, which communicates with the oil cavity 6, facilitating the inlet and outlet flow of the heat dissipation oil in the oil cavity 6. The oil holes 2-3 have similar effects as the oil grooves 2-2, which form an opening from the side to communicate with the oil cavity 6, also facilitating the inlet and outlet flow of the heat dissipation oil in the oil cavity 6. When both the oil grooves 2-2 and the oil holes 2-3 are provided, the size of the opening at the inner end of the oil cavity 6 can be increased, further facilitating the flow and circulation of the transformer oil in the oil cavity 6.

[0059] [Embodiment 4]

[0060] The basic structure and working principle of the transformer bushing of the present embodiment are the same as those of Embodiment 1 or Embodiment 2 or Embodiment 3, and the difference lies in that:

[0061] Reference Figures 4 to 7 As shown, in the present embodiment, the initial width L1 of the inner segment 1-3 is smaller than the outer diameter D1 of the threaded segment 1-5, so that the fastener 4 can be sleeved and screwed on the threaded segment 1-5 from the initial state of the inner segment 1-3; after the fastener 4 is screwed on the threaded segment 1-5, the inner terminal block is formed by flattening the initial state of the inner segment 1-3, and the width L2 of the flattened inner terminal block is greater than the outer diameter D1 of the threaded segment 1-5 and smaller than the outer diameter D2 of the inner end of the composite insulating sleeve 2. With this design, the contact area between the inner terminal block and the terminal of the transformer lead is increased, the current-carrying capacity of the connection is improved, and the local heating phenomenon is effectively reduced; and the size of the inner terminal block is shortened and widened, which makes the installation more convenient for workers, reduces the space occupied by the transformer, is beneficial to the subsequent optimization of the transformer design, and reduces the manufacturing cost of the transformer. At the same time, the flattened inner terminal block can play a role in preventing the fastener 4 from loosening, so that the fastener 4 is never loose, ensuring the long-term effective sealing of the bushing. And the width L2 of the flattened inner terminal block is smaller than the outer diameter D2 of the inner end of the composite insulating sleeve 2, which facilitates its installation on the transformer shell.

[0062] The conductive rod 1 is made of copper material as a whole. Figure 4 and Figure 5The structure of the conductive rod is shown in the initial state of the inner section 1-3, which is flattened into a plate shape after the fastener 4 is assembled, and the inner section 1-3 is pressed along the Figure 5 "arrow" direction, so that it is flattened into a plate shape, forming Figure 6 and Figure 7 the state shown. The flattened inner section 1-3 has a larger planar size, increasing the contact area with the terminal of the transformer lead. In order to facilitate connection with the terminal of the lead, the inner section 1-3 after flattening and shaping can be processed with an inner wiring hole 1-3a, forming a complete inner wiring seat. Since the overall area of the inner wiring seat is larger, more inner wiring holes 1-3a can be processed thereon to meet the wiring needs of the terminal of the transformer lead. The oil inlet and outlet hole 1-5a can be processed by drilling after the inner section 1-3 is flattened and shaped. The outer section 1-1 of the conductive rod 1 adopts a flat plate structure as an outer wiring seat, which is also provided with a plurality of outer wiring holes 1-1a.

[0063] [Example 5]

[0064] The basic structure and working principle of the transformer bushing of this embodiment are the same as those of Examples 1 to 4, except that:

[0065] As Figure 1 , Figure 2 , Figure 8 and Figure 10As shown, in the embodiment, the outer side of the composite insulating sleeve 2 is further provided with a flange 2-1 for being mounted on the transformer shell 7 through a pressing plate 8, the flange 2-1 can be in a ring table structure, the transformer shell 7 is fixed with a mounting rack 7-1, the mounting rack 7-1 can be welded on the transformer shell 7, the pressing plate 8 is mounted on the mounting rack 7-1 through a locking piece 9 and is pressed on the flange 2-1, the bottom of the flange 2-1 and the transformer shell 7 have a sealing piece, and the oil cavity 6 is communicated with the inside of the transformer shell 7 through the inner side end opening. The above-mentioned locking piece 9 comprises a screw rod and a nut mounted on the mounting rack 7-1, the transformer shell 7 is provided with a bushing mounting hole, the inner side end of the assembled bushing is disassembled from the outside of the shell into the bushing mounting hole during installation, the size of the flange 2-1 is greater than the bushing mounting hole, and the flange 2-1 is sealed with the surface of the transformer shell 7 through the sealing piece; the pressing plate 8 is pressed on the flange 2-1, the pressing plate 8 can be locked and fixed by tightening the nut on the screw rod, and then the whole bushing is fixed on the transformer shell 7. Since the fixed pin 5 is arranged between the conductive rod 1 and the composite insulating sleeve 2, at this time, the composite insulating sleeve 2 is fixed on the transformer shell 7, the conductive rod 1 cannot rotate relative to the insulating sleeve, and the stability and reliability of the connection of the inner and outer lead wires are ensured. The transformer oil in the inside of the transformer shell 7 can enter the oil cavity 6 through the above-mentioned inner side end opening, in the process of transformer operation, the heat generated by the conductive rod 1 can be transmitted to the transformer oil in the oil cavity 6, with the inflow and outflow of the transformer oil, the heat is taken away, the overall temperature of the bushing is reduced, and the working life and operation stability of the bushing are improved.

[0066] Compared with the prior art, the transformer bushing has the following advantages:

[0067] (1) By arranging the fixed pin between the composite insulating sleeve and the conductive rod, the conductive rod and the insulating sleeve cannot rotate relative to each other, thereby effectively solving the problem that the rotation of the conductive rod affects the stability and reliability of the connection of the inner and outer lead wires; and the fixed pin can also fix the composite insulating sleeve and the conductive rod, and can still ensure the effective sealing of the bushing when the fastener is loose, thereby improving the sealing reliability of the transformer bushing;

[0068] (2) The conductive rod adopts a threaded section with a circular cross section, so that the fastener and the threaded section can be connected by complete threads, the locking stability of the fastener and the threaded section is improved, and the fastener is effectively prevented from loosening; at the same time, the oil inlet and outlet of the oil cavity in the bushing are realized by the oil channel or oil hole arranged at the inner side end of the composite insulating sleeve, the heat dissipation effect of the bushing is ensured, and the overall service life and thermal stability of the bushing are improved;

[0069] (3) After the fastener is screwed onto the threaded section, the inner section in the initial state is flattened to form an inner terminal block. The width L2 of the inner terminal block formed by flattening is larger than the outer diameter D1 of the threaded section and smaller than the outer diameter D2 of the inner end of the composite insulating sleeve, thereby increasing the contact area between the inner terminal block and the transformer lead terminal, improving the current carrying capacity of the connection, and effectively reducing the local heating phenomenon. In addition, the size of the inner terminal block is shortened and widened, which makes it more convenient for workers to install, can reduce the space occupied by the transformer, is conducive to the subsequent transformer design optimization, and reduces the transformer manufacturing cost. At the same time, the flattened inner terminal block can play a role in stopping the fastener from retreating, so that the fastener will never loosen, ensuring the long-term effective sealing of the sleeve.

[0070] The above schematically describes the present invention and its embodiments, which is not intended to be limiting. The accompanying drawings illustrate only one embodiment of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by this and, without departing from the spirit of the present invention, uninventively designs structures and embodiments similar to this technical solution, they shall fall within the scope of protection of the present invention.

Claims

1. A transformer bushing comprising an electrically conductive rod (1) and a composite insulating sleeve (2), the electrically conductive rod (1) comprising an outer section (1-1), a middle section (1-2) and an inner section (1-3) arranged in sequence, the composite insulating sleeve (2) being sleeved on the outside of the middle section (1-2) and forming an oil cavity (6) with an outer end seal and an inner end opening between the sleeve hole (2a) wall of the composite insulating sleeve (2) and the outer wall of the middle section (1-2), characterized in that: Further comprising a fixing pin (5) arranged between the composite insulating sleeve (2) and the conductive rod (1) to limit the relative rotation between the conductive rod (1) and the composite insulating sleeve (2); The conductive rod (1) is provided with a first pin hole (1-2c), the composite insulating sleeve (2) is provided with a second pin hole (2-4) opposite to the first pin hole (1-2c), one end of the fixing pin (5) is provided with an end cap (5-1), and the other end is provided with an expansion chuck (5-2), the expansion chuck (5-2) of the fixing pin (5) is inserted into the second pin hole (2-4) on one side of the composite insulating sleeve (2) and then passes through the first pin hole (1-2c) and is taken out from the second pin hole (2-4) on the other side.

2. The transformer bushing of claim 1, wherein: The cross-sectional shape of the intermediate section (1-2) is non-circular, the sleeve hole (2a) of the composite insulating sleeve (2) is a circular hole, and the oil cavity (6) is enclosed by the circular sleeve hole (2a) and the non-circular intermediate section (1-2).

3. The transformer bushing of claim 2, wherein: The intermediate section (1-2) is further provided with a plurality of oil guide holes (1-2a) penetrating the oil cavity (6) on both sides.

4. The transformer bushing of claim 1, wherein: The outer side section (1-1) and the intermediate section (1-2) are provided with a sealing platform (1-4), the intermediate section (1-2) and the inner side section (1-3) are provided with a threaded section (1-5), the outer side end face of the composite insulating sleeve (2) and the sealing platform (1-4) are sealingly matched through a sealing gasket (3), the threaded section (1-5) is provided with a fastener (4), and the fastener (4) is locked on the inner side end face of the composite insulating sleeve (2).

5. The transformer bushing of claim 4, wherein: The cross-sectional shape of the threaded section (1-5) is circular.

6. The transformer bushing of claim 5, wherein: The threaded section (1-5) is further provided with a plurality of oil inlet and outlet holes (1-5a) communicating with the oil cavity (6).

7. The transformer bushing of claim 4, wherein: The initial width L1 of the inner side section (1-3) is smaller than the outer diameter D1 of the threaded section (1-5), after the fastener (4) is screwed onto the threaded section (1-5), the inner side terminal is flattened to form an inner side terminal, and the width L2 of the flattened inner side terminal is greater than the outer diameter D1 of the threaded section (1-5) and smaller than the outer diameter D2 of the inner side end of the composite insulating sleeve (2).

8. The transformer bushing according to any one of claims 1 to 7, characterized in that: The inner side end of the composite insulating sleeve (2) is provided with a plurality of oil passage grooves (2-2) and / or oil passage holes (2-3), the oil passage grooves (2-2) are arranged on the inner side end face of the composite insulating sleeve (2) and communicate with the oil cavity (6), and the oil passage holes (2-3) are arranged on the inner side end side wall of the composite insulating sleeve (2) and communicate with the oil cavity (6).

9. The transformer bushing of claim 8, wherein: The outer side of the composite insulating sleeve (2) is further provided with a flange (2-1) for being mounted on the transformer shell (7) through a pressing plate (8), the transformer shell (7) is fixed with a mounting bracket (7-1), the pressing plate (8) is mounted on the mounting bracket (7-1) through a locking member (9) and is pressed on the flange (2-1), the flange (2-1) has a sealing member between the bottom and the transformer shell (7), and the oil cavity (6) communicates with the inside of the transformer shell (7) through the inner side end opening.

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