Balancing winding grounding device

Abstract

The invention discloses a balancing winding grounding device, and relates to the technical field of transformer box accessories, the balancing winding grounding device comprises a box cover and a wire terminal mechanism arranged on the ground, the side wall of the box cover is provided with a balancing sleeve, the balancing sleeve is connected with a grounding mechanism, the grounding mechanism comprises a copper bar and an outer reinforcing rib, the copper bar is composed of three sections of straight wires, and the outer reinforcing rib is connected with the balancing sleeve. The straight wires are connected with the copper bar, a movable hinge point I and a movable hinge point II are respectively formed at two joints, the straight wires at the two ends of the copper bar are parallel to each other, the outer reinforcing rib is lapped on the outer side wall of the copper bar, the outer reinforcing rib is matched with the copper bar in shape, and a parallelogram structure is formed. According to the copper bar, a traditional copper bar of a right-angle structure is improved to be in an inclined and bent state, manufacturing is reduced, the manufacturing process is simplified, meanwhile, due to the fact that the inclination angle of the copper bar is smaller than that of the right-angle copper bar, the copper bar keeps better memorability and plasticity, the ground vibration resistance is higher, the influence of vibration deformation of the copper bar is reduced, and the service life of the copper bar is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of transformer box accessories, in particular to a balanced winding grounding device. Background Art

[0002] Balance windings are mainly used in electrical equipment such as transformers. In multi-phase transformers, balance windings are used to balance the magnetic potential between phases. Taking a three-phase transformer as an example, during the operation of the transformer, the three-phase load may be unbalanced, which will cause unbalanced three-phase magnetic potential. Balance windings can compensate for this imbalance by generating appropriate magnetic motive force, thereby reducing the zero-sequence flux of the transformer, reducing the zero-sequence impedance, and improving the stability and reliability of the transformer operation.

[0003] Balance winding grounding refers to connecting one end or multiple points of the balance winding to the earth. The main purpose of grounding is to ensure safety and normal operation of the equipment. From a safety perspective, when the balance winding has insulation damage and other faults, resulting in high voltage on the winding, grounding can guide these abnormal voltages into the earth to avoid electric shock and further damage to the equipment.

[0004] For example, in the patent publication number: CN112992501A, "A novel method for grounding the balanced winding of a transformer", a grounding plate is welded on the bottom of the lower oil tank of the transformer, the copper bar of the balance winding lead is connected to the grounding plate through a lead made of copper tape, and the above installation is completed before the upper oil tank of the transformer is buckled. By improving the traditional balance bushing and copper bar grounding, the copper bar of the balance winding lead is connected to the grounding plate on the lower oil tank; by welding a grounding plate on the bottom of the lower oil tank, the copper bar of the balance winding lead is connected to the grounding plate with a lead made of copper tape before the upper oil tank is buckled, and fastened with fasteners.

[0005] However, in the prior art, when the transformer box is used in a construction environment such as a factory, the operation of the large equipment will cause ground vibrations. Since a portion of the balance winding copper busbar is pre-buried underground, the copper busbar is affected differently by the earthquake at different locations. The existing copper busbar is designed to be bent at a right angle, resulting in poor seismic resistance. In addition, the preparation process of the copper busbar with a right-angle structure is more difficult and not easy to operate and install. Summary of the invention

[0006] The purpose of the present invention is to provide a balanced winding grounding device to solve the problem that the grounding is led out of the balanced bushing using a copper bar, and the copper bar is bent at a right angle, which has poor anti-seismic effect and is difficult to manufacture.

[0007] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a balanced winding grounding device, comprising a box cover and a wire terminal mechanism arranged on the ground, a balanced bushing is installed on the side wall of the box cover, a grounding mechanism is connected to the balanced bushing, the grounding mechanism comprises a copper bar and an external reinforcement rib, the copper bar is composed of three sections of straight wires, and a movable hinge point 1 and a movable hinge point 2 are formed at two connection points respectively, the copper bar adjusts the bending angle through the movable hinge point 1 and the movable hinge point 2, the straight wires at both ends of the copper bar are parallel to each other, the external reinforcement rib is overlapped at the outer side wall of the copper bar, the external reinforcement rib is adapted to the shape of the copper bar, which means that the external reinforcement rib is also a three-section foldable structure, and two bending hinge points are also arranged on the surface to form a parallelogram structure. The wire terminal mechanism includes a fixed sleeve, a core rod is connected between the fixed sleeve and the box cover, two clamping plates are arranged inside the fixed sleeve, an elastic sheet is arranged between the clamping plate and the inner side wall of the fixed sleeve, the copper bar passes through the two clamping plates, and a touch plate is installed on the side wall of one of the clamping plates. The copper bar adopts a movable hinge point 1 and a movable hinge point 2 to form a three-section structure. When the part pre-buried in the ground vibrates, the bending angles of the movable hinge point 1 and the movable hinge point 2 are fine-tuned to ensure that the three sections of the copper bar remain straight. The connection between the copper bar and the wire terminal mechanism is adjustable within a certain range. The copper bar is clamped and fixed by two position-adjustable clamping plates. The two ends of the clamping plates are elastically connected to the fixed sleeve through elastic sheets to reduce the deformation of the part buried underground. At the same time, the outer wall of the copper busbar is positioned by external reinforcement ribs. Since the copper busbar and the external reinforcement ribs form a parallelogram structure, when the middle section of the copper busbar is deformed, the copper busbar pre-buried in the ground always remains parallel to the copper busbar on the ground, thereby improving stability.

[0008] Preferably, the elastic sheet is composed of an arch portion in the middle and support portions at both ends, a bending portion is formed between the arch portion and the support portion, the arch portions on both sides provide a pushing force toward the middle for the splint, and the two ends of the arch portion are supported by the support portions.

[0009] Preferably, the outer side wall of the support portion is closely overlapped with the inner side wall of the fixing sleeve, and the side wall of the arch portion is closely overlapped with the side wall of the clamping plate.

[0010] Preferably, a through groove is provided at the middle position of the arch portion.

[0011] Preferably, the outer wall of the core rod is wrapped with an insulating protective layer, an inner wire is arranged inside the core rod, the inner wire is electrically connected to the touch plate, the insulating protective layer provides protection for the inner wire, the inner wire is inside the core rod, one end of the inner wire is led out from the core rod and connected to the touch plate, and a length is reserved at the connection to ensure that the inner wire will not be too tight when the splint vibrates.

[0012] Preferably, the balancing bushing includes a balancing bushing 1 and a balancing bushing 2, and the balancing bushing 1 and the balancing bushing 2 are both connected to the copper bus. Since the balancing coil carries no load, its main purpose is to balance the third harmonic and provide the sinusoidal degree of the voltage waveform. Therefore, it is recommended that only two bushings are required to be short-circuited and then grounded through a single-phase zinc oxide lightning arrester. In this embodiment, a technical solution of two bushings, balancing bushing 1 and balancing bushing 2, is provided, which can also be modified into a technical solution of four bushings according to actual use requirements.

[0013] Preferably, the elastic sheet is made of spring steel.

[0014] Preferably, one end of the copper bar and the external reinforcement rib is installed with a wire clamp 1, and the other end of the copper bar and the external reinforcement rib is installed with a double wire clamp, and one of the double wire clamps is located at the position of the movable hinge point 2. In order to firmly fix the external reinforcement rib to the outside of the copper bar, in the ground part, the copper bar and the external reinforcement rib are connected by wire clamp 1 to keep them in close contact, and in the underground part, the copper bar and the external reinforcement rib are connected by double wire clamps to keep them in close contact.

[0015] Preferably, a wire clamp 2 is installed on the outer side wall of the copper busbar at the position of the movable hinge point 1, and the positions of the movable hinge point 1 and the movable hinge point 2 are positioned by wire clamp 2 and double wire clamps, thereby reducing the degree of positional offset of the movable hinge point 1 and the movable hinge point 2 and strengthening the parallelogram stable structure formed by the copper busbar and the external reinforcement ribs.

[0016] Preferably, the copper busbar is led to a position at least 0.5 m from the ground.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. In the present invention, the traditional right-angle copper busbar is improved into an inclined and bent state, which reduces the production cost and simplifies the manufacturing process. At the same time, since the inclination angle of the copper busbar is smaller than that of the right-angle copper busbar, the copper busbar maintains better memory and shaping, has a higher ability to resist ground vibration, reduces the influence of the copper busbar's deformation due to vibration, and improves the service life of the copper busbar.

[0018] 2. In the present invention, external reinforcing ribs are installed on the outer side wall of the copper bar, and the shape of the external reinforcing ribs is consistent with that of the copper bar, thereby forming a parallelogram structure with the copper bar, so that the two ends of the copper bar remain parallel when subjected to shock, reducing the deformation of the copper bar and providing structural stability.

[0019] 3. In the present invention, the copper busbar is connected through two freely movable clamping plates, and the two ends of the clamping plates provide pre-tightening force through arched elastic sheets. On one hand, the pre-tightening force can be used to fix the copper busbar to ensure that the copper busbar and the wire terminal mechanism are always connected, and on the other hand, the material properties of the spring steel can be used to absorb the vibration energy generated by the copper busbar to provide a protective effect for the copper busbar.

[0020] 4. In the present invention, an inner conductor is arranged inside the core rod, and a certain length is reserved at the connection between the inner conductor and the contact plate, so that the clamping plate can swing with the vibration of the copper busbar, avoiding the problem of the inner conductor being too tight, and allowing the wire terminal mechanism to always be in a pass state during vibration.

[0021] 5. In the present invention, a wire clamp 1 is installed on the ground portion of the copper bar and the external reinforcement ribs, and a double wire clamp is installed on the underground portion of the copper bar and the external reinforcement ribs, so that the external reinforcement ribs and the copper bar fit together to reduce the positional offset of the movable hinge 1 and the movable hinge 2, thereby strengthening the parallelogram stable structure formed by the copper bar and the external reinforcement ribs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of a grounding device in the prior art; Figure 2 It is a side structural schematic diagram of the balanced winding grounding device of the present invention; Figure 3 It is a front structural schematic diagram of the balanced winding grounding device of the present invention; Figure 4 It is a structural schematic diagram of the grounding mechanism in the balanced winding grounding device of the present invention; Figure 5 It is a structural schematic diagram of the neutral terminal mechanism of the balanced winding grounding device of the present invention; Figure 6 It is a schematic diagram of the structure of the elastic sheet in the balanced winding grounding device of the present invention; Figure 7 The diagram is a simplified diagram of the anti-vibration principle of the grounding mechanism in the balanced winding grounding device of the present invention.

[0023] In the figure: 1. balancing bushing; 11. balancing bushing 1; 12. balancing bushing 2; 2. box cover; 3. grounding mechanism; 31. copper busbar; 32. external reinforcement rib; 33. wire clamp 1; 34. wire clamp 2; 35. movable hinge 1; 36. movable hinge 2; 37. double wire clamp; 4. wire terminal mechanism; 41. core rod; 42. fixing sleeve; 43. clamp; 44. elastic sheet; 440. through groove; 441. arch; 442. supporting part; 443. bending part; 45. touch plate; 46. inner conductor; 5. right-angle lead. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the implementation regulations described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Example 1: Reference Figure 1-Figure 7 As shown: a balanced winding grounding device, including a box cover 2 and a wire terminal mechanism 4 set on the ground, a balanced bushing 1 is installed on the side wall of the box cover 2, and a grounding mechanism 3 is connected to the balanced bushing 1. The grounding mechanism 3 includes a copper bar 31 and an external reinforcing rib 32. The copper bar 31 is composed of three straight wires, and a movable hinge 1 35 and a movable hinge 2 36 are formed at two connection points respectively. The copper bar 31 adjusts the bending angle through the movable hinge 1 35 and the movable hinge 2 36. The straight wires at both ends of the copper bar 31 are parallel to each other. The external reinforcing rib 32 is overlapped at the outer side wall of the copper bar 31. The external reinforcing rib 32 is adapted to the shape of the copper busbar 31, which means that the outer reinforcing rib 32 is also a three-section foldable structure, and two bending hinge points are also arranged on the surface to form a parallelogram structure. The wire terminal mechanism 4 includes a fixed sleeve 42, a core rod 41 is connected between the fixed sleeve 42 and the box cover 2, two clamping plates 43 are arranged inside the fixed sleeve 42, and an elastic sheet 44 is arranged between the clamping plate 43 and the inner side wall of the fixed sleeve 42. The copper busbar 31 passes through the two clamping plates 43, and a touch plate 45 is installed on the side wall of one of the clamping plates 43. The copper busbar 31 is led to a position at least 0.5m above the ground.

[0026] In this embodiment, the balancing bushing 1 can be installed on the side wall of the box cover 2 by being grounded through a single-phase zinc oxide arrester. The mounting base of the arrester is insulated from the box cover 2. The wire terminal mechanism 4 is pre-buried 0.5 meters below the ground surface. When the transformer is in use, the ground vibrates, which causes the copper bar 31 to swing up and down. The swing amplitude is very small and the frequency is high, which is also easy to affect the structure of the copper bar 31. If a traditional right-angle lead 5 is used, it is more likely to cause the right-angle lead 5 to bend due to the right-angle structure of the connection. The copper bar 31 adopts a three-section structure with a movable hinge point 1 35 and a movable hinge point 2 36. When the part pre-buried in the ground vibrates, the movable hinge The bending angles of point 1 35 and movable hinge point 2 36 are fine-tuned to ensure that the three sections of the copper busbar 31 remain straight. The connection between the copper busbar 31 and the wire terminal mechanism 4 is adjustable within a certain range. The copper busbar 31 is clamped and fixed by two position-adjustable clamping plates 43. The two ends of the clamping plates 43 are elastically connected to the fixing sleeve 42 through elastic sheets 44 to reduce the deformation of the buried part. At the same time, the outer wall of the copper busbar 31 is positioned by the outer reinforcing ribs 32. Since the copper busbar 31 and the outer reinforcing ribs 32 form a parallelogram structure, when the middle section of the copper busbar 31 is deformed, the copper busbar 31 pre-buried in the ground always remains parallel to the copper busbar 31 on the ground, thereby improving stability. The rated voltage level of the balance winding coil is 10.5kV. According to GB / T17468-2019 Power Transformer Selection Guidelines: The rated capacity of the stable balance winding shall generally not be less than 35% of the rated capacity of the transformer. The material and winding process of the balance winding coil are consistent with the high and low voltage side windings of the main transformer. The insulation level and short-circuit withstand capacity meet the national standard requirements. The balance bushing 1 is connected to form an open triangle inside the box cover 2, and the two ends of the opening are led out. When in use, the two terminals are first short-circuited with a copper bar 31, and the cross-sectional area of ​​the copper bar 31 is selected to be not less than the cross-sectional area of ​​the bushing conductive rod.

[0027] Because no matter the transformer is in normal operation or other windings fail during operation, the zero-sequence component current caused by it only flows in the triangle, unless the balancing bushing 1 has a grounding point inside the box cover 2. The magnitude of the ground current of the balancing bushing 1 is determined by the capacitance of the balancing bushing 1 to the ground and to other windings. In order to avoid the influence of point suspension, the open triangle should be directly connected to the grounding grid through the grounding copper bus 31 or cable after external short circuit, and the selection of its cross section only needs to consider its mechanical strength. This wiring method is simple to operate. The DC resistance of the winding can be conveniently measured in the transformer factory. Analysis of the position of the balance bushing 1: The conventional coil arrangement of conventional 220kV products with balance windings is iron core - balance coil - low voltage coil - high voltage coil - voltage regulating coil. If the balance coil is placed on the outermost side, that is, iron core - low voltage coil - high voltage coil - voltage regulating coil - balance coil, the cost of the balance bushing 1 can be reduced if the performance parameters are calculated consistently.

[0028] Embodiment 2: According to Figure 4 , Figure 5 and Figure 6 As shown, the elastic sheet 44 is composed of a middle arch 441 and support portions 442 at both ends, and a bending portion 443 is formed between the arch 441 and the support portion 442. The outer wall of the support portion 442 is closely overlapped with the inner wall of the fixing sleeve 42, and the side wall of the arch 441 is closely overlapped with the side wall of the clamping plate 43. A through groove 440 is provided at the middle position of the arch 441. The elastic sheet 44 is made of spring steel.

[0029] In this embodiment, in order to provide a pre-tightening clamping advantage for the copper busbar 31 of the connecting wire terminal mechanism 4, the elastic sheet 44 is designed to have an arch bridge appearance structure and is made of spring steel material. The arches 441 on both sides provide a pushing force toward the middle for the clamping plate 43. The two ends of the arch 441 are supported by the supporting parts 442. The elastic force in the arch 441 is maintained by the material properties. When the ground vibrates, the copper busbar 31 drives the clamping plates 43 at both ends to move, and the arches 441 on both sides will also produce high-frequency deformation.

[0030] Embodiment 3: According to Figure 5 and Figure 6 As shown, the outer wall of the core rod 41 is wrapped with an insulating protective layer, and an inner wire 46 is arranged inside the core rod 41 , and the inner wire 46 is electrically connected to the contact plate 45 .

[0031] In this embodiment, the insulating protective layer provides protection for the internal inner conductor 46. The inner conductor 46 is inside the core rod 41. One end of the inner conductor 46 is led out from the core rod 41 and connected to the touch plate 45. A length is reserved at the connection to ensure that the inner conductor 46 will not be too tight when the clamping plate 43 vibrates.

[0032] Embodiment 4: According to Figure 2 and Figure 3 As shown, the balancing bushing 1 includes a balancing bushing 11 and a balancing bushing 2 12 , and both the balancing bushing 11 and the balancing bushing 2 12 are connected to the copper bus 31 .

[0033] In this embodiment, since the balance coil carries no load, its main purpose is to balance the third harmonic and provide the sinusoidal degree of the voltage waveform. Therefore, it is recommended that only two bushings are required to be short-circuited and then grounded through a single-phase zinc oxide arrester. In this embodiment, a technical solution of two bushings, namely, a balance bushing 11 and a balance bushing 2 12, is provided, which can also be modified into a technical solution of four bushings according to actual use requirements.

[0034] Embodiment 5: According to Figure 4 As shown, a wire clamp 1 33 is installed at one end of the copper bar 31 and the outer reinforcement rib 32, and a double wire clamp 37 is installed at the other end of the copper bar 31 and the outer reinforcement rib 32, and one of the double wire clamps 37 is located at the position of the movable hinge 2 36. A wire clamp 2 34 is installed at the position of the movable hinge 1 35 on the outer side wall of the copper bar 31.

[0035] In this embodiment, in order to firmly fix the external reinforcement rib 32 on the outside of the copper busbar 31, on the ground, the copper busbar 31 and the external reinforcement rib 32 are connected by a wire clamp 1 33 to keep them in close contact. On the underground part, the copper busbar 31 and the external reinforcement rib 32 are connected by a double wire clamp 37 to keep them in close contact. At the same time, the positions of the movable hinge 1 35 and the movable hinge 2 36 are positioned by a wire clamp 2 34 and a double wire clamp 37 to reduce the degree of positional deviation of the movable hinge 1 35 and the movable hinge 2 36, thereby strengthening the parallelogram stable structure formed by the copper busbar 31 and the external reinforcement rib 32.

[0036] The use method and working principle of the device: First, the balance bushing 1 is connected to form an open triangle inside the box cover 2, and the two ends of the opening are led out, and the balance bushing 1 11 and the balance bushing 2 12 are short-circuited with a copper bus 31; Then, install the outer reinforcing rib 32 on the outside of the copper bar 31, install the wire clamp 1 33 on one end of the copper bar 31 and the outer reinforcing rib 32, install the double wire clamp 37 on the other end of the copper bar 31 and the outer reinforcing rib 32, and install one double wire clamp 37 at the position of the movable hinge point 2 36, and install the wire clamp 2 34 at the position of the movable hinge point 1 35, and tighten the screws to fix the clamps; Then, push the clamping plates 43 on both sides outward, pass the copper bar 31 through the clamping plates 43, and use the elasticity of the two elastic sheets 44 to tighten the copper bar 31 in the middle, so that the copper bar 31 is connected to the contact plate 45 and directly connected to the grounding grid; Finally, the copper busbar 31 is pre-buried underground; When vibrating, the positions of the two ends of the copper busbar 31 are offset, and the bending angles of the movable hinge 1 35 and the movable hinge 2 36 are fine-tuned to ensure that the three sections of the copper busbar 31 remain straight. The outer wall of the copper busbar 31 is positioned by the external reinforcement ribs 32 to form a parallelogram structure. The copper busbar 31 pre-buried in the ground always remains parallel to the copper busbar 31 on the ground, thereby improving stability.

[0037] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A balanced winding grounding device, comprising a box cover (2) and a wire terminal mechanism (4) arranged on the ground, wherein a balanced bushing (1) is installed on the side wall of the box cover (2), characterized in that: The balancing bushing (1) is connected to a grounding mechanism (3), the grounding mechanism (3) comprising a copper bar (31) and an external reinforcement rib (32), the copper bar (31) comprising three straight conductors, and forming a first movable hinge (35) and a second movable hinge (36) at two connection points, respectively, the straight conductors at both ends of the copper bar (31) being parallel to each other, the external reinforcement rib (32) being overlapped at the outer side wall of the copper bar (31), and the shape of the external reinforcement rib (32) being adapted to that of the copper bar (31). The wire terminal mechanism (4) comprises a fixing sleeve (42), a core rod (41) is connected between the fixing sleeve (42) and the box cover (2), two clamping plates (43) are arranged inside the fixing sleeve (42), an elastic sheet (44) is arranged between the clamping plates (43) and the inner side wall of the fixing sleeve (42), the copper bar (31) passes through between the two clamping plates (43), and a contact plate (45) is installed on the side wall of one of the clamping plates (43).

2. The balanced winding grounding device according to claim 1, characterized in that: The elastic sheet (44) is composed of a middle arch portion (441) and support portions (442) at both ends, and a bending portion (443) is formed between the arch portion (441) and the support portion (442).

3. The balanced winding grounding device according to claim 2, characterized in that: The outer wall of the support portion (442) is tightly overlapped with the inner wall of the fixing sleeve (42), and the side wall of the arch portion (441) is tightly overlapped with the side wall of the clamping plate (43).

4. The balanced winding grounding device according to claim 3, characterized in that: A through groove (440) is provided at the middle position of the arch portion (441).

5. The balanced winding grounding device according to claim 1, characterized in that: The outer wall of the core rod (41) is wrapped with an insulating protective layer, and an inner conductor (46) is arranged inside the core rod (41), and the inner conductor (46) is electrically connected to the contact plate (45).

6. The balanced winding grounding device according to claim 1, characterized in that: The balancing bushing (1) comprises a balancing bushing 1 (11) and a balancing bushing 2 (12), and both the balancing bushing 1 (11) and the balancing bushing 2 (12) are connected to a copper busbar (31).

7. The balanced winding grounding device according to claim 1, characterized in that: The elastic sheet (44) is made of spring steel.

8. The balanced winding grounding device according to claim 1, characterized in that: One end of the copper bar (31) and the external reinforcement rib (32) is installed with a wire clamp 1 (33), and the other end of the copper bar (31) and the external reinforcement rib (32) is installed with a double wire clamp (37), and one of the double wire clamps (37) is located at the position of the movable hinge point 2 (36).

9. The balanced winding grounding device according to claim 1, characterized in that: A second wire clamp (34) is installed on the outer side wall of the copper bar (31) at the position of the first movable hinge point (35).

10. The balanced winding grounding device according to claim 1, characterized in that: The copper busbar (31) is led to a position at least 0.5 meters from the ground.

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