Anti-short-circuit structure of oil-immersed distribution transformer

Abstract

The invention relates to the technical field of transformer accessories, and discloses an oil-immersed distribution transformer anti-short-circuit structure which comprises an upper clamping piece, a lower clamping piece and a side pressing plate, connecting plates are arranged at the two ends of the side pressing plate respectively, the two connecting plates are connected with the upper clamping piece and the lower clamping piece respectively, each of the upper clamping piece and the lower clamping piece comprises two web plates which are oppositely arranged, and the web plates are connected with the side pressing plate. The two oppositely-arranged web plates are connected together through a side screw rod, mounting grooves are formed in the end portions of all the web plates, lug plates are arranged at the two ends of the connecting plate respectively, and the two lug plates on the connecting plate are inserted into the mounting grooves of the web plates on the corresponding sides respectively. When the coil is short-circuited, the generated radial short-circuit force directly acts on the side pressing plate and acts on the clamping piece through the connecting plate. By the adoption of the connecting structure, the stress directions of the connecting plates and the clamping pieces are the highest stress strength directions, and the short circuit resistance of the transformer can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of transformer accessories, and in particular to an anti-short-circuit structure of an oil-immersed distribution transformer. Background Art

[0002] The ability of oil-immersed distribution transformer coils to withstand sudden short circuits has always been a key and challenging aspect of transformer design and manufacturing. Unlike resin-cast dry-type transformer coils, oil-immersed transformer coils lack overall rigidity and structural strength. In the event of a sudden short circuit, the enormous radial short-circuit force can easily cause coil deformation, excessive performance, or even damage.

[0003] The gap between the oil transformer coils is small and is limited by the iron core, so it is not easy to deform when short-circuited. However, the outer coils of phases A and C are subjected to horizontal outward radial electromagnetic forces when short-circuited. If there is no restraint device, it is easy to produce convex deformation. Currently, most side pressure plates are used on the outer sides of phases A and C to prevent coil deformation. The connection between the conventional side pressure plate and the clamp is to open holes in the side pressure plate and the clamp web and connect them directly with bolts. This structure can be seen in Figure 1 However, in this connection method, the bolts are subjected to shear force, and are easily damaged by shear, resulting in insufficient short-circuit resistance. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide an oil-immersed distribution transformer anti-short-circuit structure to solve one or more problems in the prior art.

[0005] To achieve the above object, the technical solution of the present invention is as follows: A short-circuit protection structure for an oil-immersed distribution transformer comprises an upper clamp, a lower clamp and a side pressure plate. Connecting plates are provided at both ends of the side pressure plate, and the two connecting plates are connected to the upper clamp and the lower clamp respectively. The upper clamp and the lower clamp each comprise two oppositely disposed webs, which are connected together by side screws. Mounting grooves are provided at the ends of all webs, and ear plates are provided at both ends of the connecting plate, and the two ear plates on the connecting plate are respectively inserted into the mounting grooves of the corresponding side webs.

[0006] With this technical solution, when a coil short-circuits, the resulting radial short-circuit force acts directly on the side pressure plates and, through the connecting plate, on the clamp. This connection structure places the forces acting on both the connecting plate and the clamp in the direction of their highest strength, improving the transformer's short-circuit resistance. Furthermore, the connecting plate and clamp are not bolted together, eliminating the risk of shear forces on the bolts.

[0007] Furthermore, the side edge of the web close to the side pressure plate is bent toward the side away from the oppositely arranged web to form a bent plate, the mounting groove is opened at the junction of the web and the bent plate, and one end of the mounting groove extends to the bent plate.

[0008] Through the above technical solution, the connecting plate and the clamp are in surface contact, and the contact area is large, which prevents the plate from being torn and deformed due to stress concentration.

[0009] Furthermore, a pressing tongue is provided on the side wall of the mounting groove on the web, and the pressing tongue abuts against the side of the corresponding ear plate facing the web.

[0010] Through the above technical solution, a pad is filled between the clamp and the coil, and the ear plate is pressed on the pad by the pressing tongue on the clamp. In addition, the mounting groove limits the ear plate horizontally, so that the connecting plate is completely fixed, making the structure more stable.

[0011] Furthermore, the connecting plate is provided with a plurality of plug slots, and both ends of the side pressure plate are provided with a plurality of plugs, and the side pressure plate is connected to the connecting plate by inserting the plugs into the plug slots.

[0012] The above technical solution uses a plug-in assembly structure for the side pressure plate. The plug of the side pressure plate is placed in the socket of the upper and lower connecting plates, and the side pressure plate is pressed against the coil. This structure does not require bolts, eliminating the risk of bolts loosening and falling due to vibration during transformer operation.

[0013] Furthermore, the side pressure plate includes a main board and two support plates, the two support plates are respectively located on both sides of the main board, and the support plates are arranged perpendicular to the main board, and the plug is arranged on the end of the support plate.

[0014] Through the above technical solution, the side pressure plate is the main bearing structure of the short-circuit force, and the U-shaped section has a large moment of inertia and performs outstandingly in resisting bending.

[0015] Furthermore, a limiting block is provided at the end of the main board, a limiting slot is provided on the connecting plate, and the width of the plugging slot is greater than the width of the plug.

[0016] With the above technical solution, the edge of the connector plate's slot is a stress concentration area. To improve the structure's short-circuit resistance and avoid stress concentration, a rounded corner transition is generally used at the slot edge. This inevitably makes the slot larger than the side pressure plate plug, allowing the side pressure plate to move within a certain range. Therefore, a stop block is added between the connector plate and the side pressure plate. The stop block only serves as a positioning function. This not only avoids stress concentration and improves short-circuit resistance, but also fixes the side pressure plate in place, preventing it from moving.

[0017] Furthermore, the connecting plate includes a connecting portion and a mounting portion, the connecting portion is arranged perpendicular to the mounting portion, the ear plates are respectively arranged on both sides of the connecting portion, and the mounting portion and the side pressure plate are connected by bolts.

[0018] Through the above technical solution, the bolt is arranged perpendicular to the coil and will not be sheared by the short-circuit force, and the degree of tightening of the side pressure plate to the coil can be adjusted by the bolt.

[0019] Furthermore, a weight-reducing groove is provided on the connecting plate.

[0020] Through the above technical solution, in order to further reduce the weight of the device body, the connecting plate adopts a hollow structure.

[0021] Furthermore, an arc-shaped transition is provided between the main plate and the ear plate of the connecting plate.

[0022] Furthermore, the width of the main plate of the side pressure plate is smaller than the distance between the two webs of the same clamp.

[0023] With this technical solution, since the short-circuit deformation of the coil is mainly concentrated in the straight section, the width of the side pressure plate can be reduced, and only the area of ​​the coil that is prone to deformation can be compressed. This side pressure plate assembly structure reduces the weight of the device body and reduces material costs.

[0024] Compared to existing technologies, this invention offers the following beneficial technical effects: When a coil short-circuits, the resulting radial short-circuit force acts directly on the side pressure plates and, through the connecting plates, on the clamps. This connection structure ensures that both the connecting plates and the clamps are subjected to forces in the direction of their highest strength, improving the transformer's short-circuit resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic structural diagram showing a side pressure plate directly connected to a clamp via bolts in the prior art is shown.

[0026] Figure 2 The invention shows an oil-immersed distribution transformer anti-short-circuit structure provided in the first embodiment.

[0027] Figure 3 yes Figure 2 A magnified view of center.

[0028] Figure 4 A schematic structural diagram of the web provided in the first embodiment of the present invention is shown.

[0029] Figure 5 A structural schematic diagram of a connecting plate provided in the first embodiment of the present invention is shown.

[0030] Figure 6 A schematic structural diagram of a side pressure plate provided in embodiment 1 of the present invention is shown.

[0031] Figure 7 A schematic structural diagram of a connecting plate provided in the second embodiment of the present invention is shown.

[0032] Figure 8 An anti-short-circuit structure of an oil-immersed distribution transformer provided by the third embodiment of the present invention is shown.

[0033] Figure 9 A schematic structural diagram of a connecting plate provided in the third embodiment of the present invention is shown.

[0034] Figure 10 A schematic structural diagram of a side pressure plate provided in the third embodiment of the present invention is shown.

[0035] Figure numerals: 1. Side pressure plate; 11. Main board; 12. Support plate; 13. Plug; 14. Limit block; 2. Web plate; 21. Mounting groove; 22. Pressing tongue; 3. Connecting plate; 31. Ear plate; 32. Plug slot; 33. Limiting slot; 4. Pull screw; 5. Side screw; 6. Bending plate; 7. Weight-reducing slot; 8. Connecting part; 9. Mounting part. DETAILED DESCRIPTION Example 1

[0036] An oil-immersed distribution transformer short-circuit resistant structure, see Figure 2 , comprising an upper clamp and a lower clamp, both having identical structures. Several tension screws 4 are connected between the upper and lower clamps, securing them together. Side pressure plates 1 are provided at each end of the upper and lower clamps. Both ends of the side pressure plates 1 are connected to connecting plates 3, which are secured to the corresponding ends of the upper and lower clamps, respectively, via the two connecting plates 3.

[0037] The above clamp is used as an example to further introduce the clamp structure. Figure 2 The upper clamp includes two webs 2. Both sides of the webs 2 are bent to form bent plates 6. The two bent plates 6 of the same web 2 are parallel to each other, but bent in opposite directions. The bent plate 6 on one side is used to squeeze the end face of the iron core and play the role of limiting the iron core; the bent plate 6 on the other side is provided with a bolt hole for the tension screw 4 to fix and connect the upper and lower clamps. The two bent plates 6 are arranged perpendicular to the webs 2. A number of side screws 5 are connected between the two webs 2, and the two webs 2 are connected into an integrated upper clamp by the side screws 5. The two connected webs 2 are arranged parallel to each other.

[0038] See also Figure 3 、 Figure 4Both ends of the web 2 are provided with mounting grooves 21. The mounting grooves 21 are provided at the junction of the web 2 and the bent plate 6 with bolt holes, and one end of the mounting groove 21 extends to the corresponding bent plate 6. The side wall of the mounting groove 21 located on the web 2 is provided with a pressing tongue 22. The pressing tongue 22 extends from the side wall of the mounting groove 21 away from the adjacent bent plate 6. There is an arc transition between the pressing tongue 22 and the side wall of the mounting groove 21.

[0039] See also Figure 3 、 Figure 5 , ear plates 31 are respectively provided at both ends of the connecting plate 3, and the two ear plates 31 and the main body of the connecting plate 3 form a "convex" cross-section. The ear plates 31 and the main body of the connecting plate 3 are integrally formed. And an arc-shaped transition is provided between the main board 11 of the connecting plate 3 and the ear plates 31. A plurality of plug-in slots 32 and a limiting slot 33 are provided on the main body of the connecting plate 3. The plurality of plug-in slots 32 are arranged in parallel, and the length direction of the limiting slot 33 is perpendicular to the length direction of the plug-in slot 32. An arc transition is used between the adjacent slot walls of the plug-in slot 32.

[0040] See also Figure 2 、 Figure 3 The two lugs 31 on the connecting plate 3 are inserted into the mounting slots 21 of the two webs 2 of the same clamp. Because the two opposing webs 2 are already connected via the side screws 5, the two webs 2 together clamp the connecting plate 3, securing the connecting plate 3 perpendicular to the web 2 surfaces. The lugs 31 inserted into the mounting slots 21 are constrained by the side walls of the slots 21 and the retaining tongues 22, allowing only a small degree of movement.

[0041] Furthermore, when the entire structure is actually applied to a transformer, insulating cardboard is filled between the side pressure plate 1 and the coil, and pads are filled between the coil and the clamp. On the one hand, the lugs 31 abut against the sidewalls of the mounting slots 21 closer to the outside along the length of the web 2. On the other hand, the pressing tongues 22 abut against the side of the corresponding lugs 31 facing the web 2, and abut the lugs 31 against the pads, further restricting their movement and making the overall structure more stable.

[0042] See also Figure 3 、 Figure 6 The side pressure plate 1 comprises a main plate 11 and two support plates 12. The two support plates 12 are located on either side of the main plate 11 and are arranged perpendicular to the main plate 11, giving the side pressure plate 1 a U-shaped cross-section. The support plates 12 and the main body are integrally bent. Plugs 13 extend from each end of each support plate 12, and stoppers 14 extend from each end of the main plate 11.

[0043] The length of the plug 13 matches the length of the insertion slot 32 , but the width of the plug 13 is smaller than the width of the insertion slot 32 ; the length of the limit block 14 matches the length of the limit slot 33 , and the width of the limit block 14 is smaller than the width of the limit slot 33 .

[0044] The side pressure plate 1 is connected to the connecting plate 3 by inserting the plug 13 into the plug slot 32 and the limit block 14 into the limit slot 33. The two connecting plates 3 fixed on the corresponding clamps then clamp the side pressure plate 1 together, so that the side pressure plate 1 is indirectly fixed to the clamp.

[0045] And it can be seen that, since the side pressure plate 1 is no longer required to be directly connected to the clamp, there is no mandatory requirement for the width of the side pressure plate 1. Taking into account that the side pressure plate 1 is mainly used to generate radial short-circuit forces for the straight segments of the coil, in order to save materials and reduce weight, the width of the main board 11 of the side pressure plate 1 is smaller than the distance between the two webs 2 of the same clamp, so that the main board 11 of the side pressure plate 1 basically covers the straight segments of the coil in actual use.

[0046] The specific assembly steps are as follows: 1. Install a connecting plate 3 at each end of the lower clamp, and place the two lugs 31 of the connecting plate 3 into the mounting grooves 21 of the lower clamp respectively; 2. Put the coil on the iron core column and insert it back to install the iron yoke; 3. Place the plug 13 of the side pressure plate 1 into the slot of the lower connecting plate 3 and press the side pressure plate 1 onto the coil; 4. Install the upper connecting plate 3 so that the plug 13 of the side pressure plate 1 is in the slot of the connecting plate 3; 5. Install the upper clamp so that the lugs 31 of the connecting plate 3 fall into the corresponding mounting slots 21 of the upper clamp. Tighten the side screws 5 and the pull screws 4 on the clamp. When the bolts are fully tightened, the clamp presses the connecting plate 3 against the coil, and the side pressure plate 1 is trapped in the slots of the connecting plate 3. Example 2

[0047] The difference from the first embodiment is that, see Figure 7 The connecting plate 3 is provided with a weight-reducing groove 7. Since the weight-reducing groove 7 occupies a large space, the connecting plate 3 is no longer provided with a limiting groove 33. When the connecting plate 3 and the side pressure plate 1 are connected, the limiting block 14 on the side pressure plate 1 can be inserted into the weight-reducing groove 7, and the limiting block 14 is limited in the corresponding direction by the side wall of the weight-reducing groove 7. Example 3

[0048] The difference from the first embodiment is that the connection method between the connecting plate 3 and the side pressure plate 1 is different, and the structures of the connecting plate 3 and the side pressure plate 1 are also different accordingly.

[0049] For details, see Figure 8The connecting plate 3 includes a connecting portion 8 and a mounting portion 9 that are integrally bent. The connecting portion 8 is arranged perpendicular to the mounting portion 9. Ear plates 31 are respectively arranged on both sides of the connecting portion 8. The side pressure plate 1 is not provided with a plug 13 and a limit block 14, but is connected to the mounting portion 9 by bolts.

[0050] In Example 1, to ensure that side pressure plate 1 provides sufficient pressure against the coil, insulating cardboard is placed between the side pressure plate 1 and the coil. The thickness of the insulating cardboard needs to be adjusted according to the actual size of the coil produced each time. In this embodiment, however, the coil is secured by tightening the bolts on side pressure plate 1, eliminating the need to adjust the thickness of the insulating cardboard.

[0051] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0052] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. An oil-immersed distribution transformer anti-short-circuit structure, comprising an upper clamping member, a lower clamping member and a side pressure plate (1), characterized in that: The two ends of the side pressure plate (1) are respectively provided with connecting plates (3), and the two connecting plates (3) are respectively connected to the upper clamp and the lower clamp. The upper clamp and the lower clamp each include two oppositely arranged webs (2), and the two oppositely arranged webs (2) are connected together through a side screw (5). The ends of all webs (2) are provided with mounting grooves (21). The two ends of the connecting plate (3) are respectively provided with ear plates (31), and the two ear plates (31) on the connecting plate (3) are respectively inserted into the mounting grooves (21) of the corresponding side webs (2).

2. The oil-immersed distribution transformer anti-short-circuit structure according to claim 1, characterized in that: The side edge of the web (2) close to the side pressure plate (1) is bent toward a side away from the oppositely arranged web (2) to form a bent plate (6); the mounting groove (21) is provided at the junction of the web (2) and the bent plate (6), and one end of the mounting groove (21) extends onto the bent plate (6).

3. The anti-short-circuit structure of an oil-immersed distribution transformer according to claim 2, characterized in that: The side wall of the mounting groove (21) located on the web (2) is provided with a pressing tongue (22), and the pressing tongue (22) abuts against the side of the corresponding ear plate (31) facing the web (2).

4. The oil-immersed distribution transformer anti-short-circuit structure according to claim 1, characterized in that: The connecting plate (3) is provided with a plurality of plug slots (32), and both ends of the side pressure plate (1) are provided with a plurality of plugs (13). The side pressure plate (1) is connected to the connecting plate (3) by inserting the plugs (13) into the plug slots (32).

5. The anti-short-circuit structure of an oil-immersed distribution transformer according to claim 4, characterized in that: The side pressure plate (1) comprises a main plate (11) and two support plates (12), the two support plates (12) are respectively located on both sides of the main plate (11), and the support plates (12) are arranged perpendicular to the main plate (11), and the plug (13) is arranged on the end of the support plate (12).

6. The anti-short-circuit structure of an oil-immersed distribution transformer according to claim 5, characterized in that: A limiting block (14) is provided at the end of the main board (11), a limiting slot (33) is provided on the connecting plate (3), and the width of the plug slot (32) is greater than the width of the plug (13).

7. The oil-immersed distribution transformer anti-short-circuit structure according to claim 1, characterized in that: The connecting plate (3) comprises a connecting portion (8) and a mounting portion (9), the connecting portion (8) is arranged perpendicular to the mounting portion (9), the ear plates (31) are respectively arranged on both sides of the connecting portion (8), and the mounting portion (9) and the side pressure plate (1) are connected by bolts.

8. The anti-short-circuit structure of an oil-immersed distribution transformer according to claim 4, characterized in that: The connecting plate (3) is provided with a weight-reducing groove (7).

9. The anti-short-circuit structure of an oil-immersed distribution transformer according to claim 1, characterized in that: An arc-shaped transition is provided between the main plate (11) and the ear plate (31) of the connecting plate (3).

10. The anti-short-circuit structure of an oil-immersed distribution transformer according to claim 1, characterized in that: The width of the main plate (11) of the side pressure plate (1) is smaller than the distance between the two webs (2) of the same clamp.

Images