A stable compression structure for reducing partial discharge of a dry-type transformer

Abstract

The utility model discloses a kind of stable pressing structures for reducing partial discharge of dry-type transformer, belong to transformer technical field, including being arranged on the winding coil upper side insulating block, clamp support and press nail;The insulating block is hemispherical structure, and recessed portion is opened in the position of its top spherical surface, the press nail is pressed in the recessed portion after passing through the clamp support, the bottom surface of the insulating block is plane and is set on the upper side of the winding coil.The stable pressing structure for reducing partial discharge of dry-type transformer solves the problem that the pressing structure of current dry transformer coil can cause field strength distortion, so as to easily exceed the allowed field strength and cause partial discharge to exceed the standard.

Description

Technical Field

[0001] This utility model relates to the field of transformer technology, and in particular to a stable clamping structure for reducing partial discharge in dry-type transformers. Background Technology

[0002] Dry-type transformers are widely used in urban power grid renovation due to their advantages such as fire resistance, explosion resistance, pollution-free operation, and simple maintenance. They are particularly suitable for important locations requiring fire resistance, explosion resistance, and moisture protection, such as high-rise buildings, airports, power plants, and commercial centers.

[0003] like Figure 1 As shown, in a traditional dry-type transformer, there are four winding clamping blocks on the upper side of the high and low voltage winding coils at the end of the windings. Each winding clamping block includes an epoxy resin insulating block 100 and a silicone rubber plate 200. These blocks are pressed against the end plane of the epoxy resin insulating block 100 by grounded flat-foot threaded pins 300. Silicone rubber plates 200 with different compression ratios are placed between the four epoxy resin insulating blocks 100 and the windings to adjust the height of the winding clamping blocks. This structure presents a problem of electric field concentration: the electric field strength applied to the air gap between the winding clamping blocks and the flat-foot threaded pins 300 is relatively large. Furthermore, the sharp edges of the metal nut heads at the ends of the flat-foot threaded pins 300 further distort the electric field strength, easily exceeding the allowable field strength and causing excessive partial discharge. Utility Model Content

[0004] In order to overcome the defects of the existing technology, this utility model provides a stable clamping structure for reducing partial discharge of dry-type transformers, so as to solve the above-mentioned problems.

[0005] The technical solution adopted by this utility model to solve its technical problem is: a stable clamping structure for reducing partial discharge of dry-type transformers, including an insulating block, a clamping bracket and a pressure nail disposed on the upper side of the winding coil; The insulating block has a hemispherical structure with a recessed portion on the top spherical surface. The pressure pin passes through the clamping bracket and is pressed into the recessed portion. The bottom surface of the insulating block is flat and is located on the upper side of the winding coil.

[0006] Preferably, the recessed portion of the insulating block is provided with a metal shielding cap, the recessed portion is a hemispherical structure, and the metal shielding cap is an arc-shaped structure that fits the wall of the recessed portion.

[0007] Optionally, the end of the pin inserted into the recess has an arc-shaped structure that mates with the metal shielding cap, and the end of the pin contacts the metal shielding cap after being inserted into the recess.

[0008] Specifically, it also includes an insulator, one end of which is inserted into the insulating block and the other end of which extends into the winding coil.

[0009] It is worth noting that the bottom surface of the insulating block has a groove, and one end of the insulator is inserted into the groove.

[0010] Preferably, the insulator is a PET separator or an insulating tube.

[0011] The beneficial effects of this invention are as follows: In the stable clamping structure for reducing partial discharge in dry-type transformers, the insulating block is made of epoxy resin and is used to support the winding coil. By setting a recessed portion, the contact area between the insulating block and the end of the pressure pin can be increased, allowing the electric field strength to be evenly distributed over a larger contact area between the pressure pin and the insulating block. According to electric field theory, the electric field strength is inversely proportional to the distance between electrodes and inversely proportional to the electrode area. Increasing the contact area can effectively reduce the electric field strength per unit area, reducing the possibility of partial discharge. In addition, the recessed design of the insulating block can optimize the electric field distribution. Since there are no sharp edges, the problem of electric field concentration caused by sharp edges can be avoided, and the electric field distortion is reduced through a smooth transition. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the clamping structure of an existing dry-type transformer coil; Figure 2 This is a schematic diagram of a stabilizing clamping structure for reducing partial discharge in a dry-type transformer, as shown in one embodiment of the present invention. Figure 3 for Figure 2 An enlarged schematic diagram of the dashed circle A; Figure 4 This is a schematic diagram of the structure of the insulating block in one embodiment of the present invention; In the diagram: 1 Winding coil; 2 Insulating block; 21 Recessed part; 22 Metal shielding cap; 23 Slot; 3 Clamping bracket; 4 Pressing nail; 5 Insulator; 100 Epoxy resin insulating block; 200 Silicone rubber sheet; 300 Flat-foot threaded pressing nail. Detailed Implementation

[0013] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding of this utility model, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0014] like Figure 2 , Figure 3 and Figure 4 As shown, a stabilizing clamping structure for reducing partial discharge in a dry-type transformer includes an insulating block 2, a clamping bracket 3, and a clamping nail 4 disposed on the upper side of the winding coil 1. The insulating block 2 has a hemispherical structure with a recess 21 on its top spherical surface. The pressure nail 4 passes through the clamping bracket 3 and is pressed into the recess 21. The bottom surface of the insulating block 2 is flat and is located on the upper side of the winding coil 1.

[0015] In the stabilizing clamping structure for reducing partial discharge in dry-type transformers, the insulating block 2 is made of epoxy resin and is used to support the winding coil 1. By providing the recessed portion 21, the contact area between the insulating block 2 and the end of the pressure pin 4 can be increased, allowing the electric field strength to be evenly distributed over a larger contact area between the pressure pin 4 and the insulating block 2. According to electric field theory, the electric field strength is inversely proportional to the distance between electrodes and inversely proportional to the electrode area. Increasing the contact area can effectively reduce the electric field strength per unit area, reducing the possibility of partial discharge. In addition, the recessed portion 21 of the insulating block 2 optimizes the electric field distribution. Since there are no sharp edges, the problem of electric field concentration caused by sharp edges can be avoided, and the electric field distortion is reduced through a smooth transition.

[0016] Specifically, the concave shape and size of insulating block 2 have a significant impact on the electric field distribution. Besides a hemispherical shape, other shapes, such as parabolic and elliptical shapes, can be considered, and the optimal shape can be found through numerical simulation. Studies have shown that a concave profile can effectively reduce the maximum tangential electric field. Insulating block 2 can be manufactured using a combination of molding and post-curing processes to reduce internal stress and microcracks. By optimizing the curing curve (e.g., segmented heating and isothermal curing), the cross-linking degree of the material can be made uniform, improving the overall mechanical properties and dielectric stability, and reducing partial discharge caused by material defects.

[0017] Preferably, the recessed portion 21 of the insulating block 2 is provided with a metal shielding cap 22, the recessed portion 21 is a hemispherical structure, and the metal shielding cap 22 is an arc-shaped structure that fits the wall of the recessed portion 21.

[0018] In this embodiment, the recess 21 is a hollow hemispherical structure with an arc-shaped inner wall. The metal shielding cap 22 is generally made of copper and is fixed to the inner wall of the recess 21 of the insulating block 2 by casting to form an arc-shaped structure. This ensures that the metal shielding cap 22 is completely fitted to the inner wall of the recess 21 of the insulating block 2, avoiding electric field concentration caused by interface bubbles or gaps.

[0019] Optionally, the end of the pressure pin 4 that is inserted into the recess 21 has an arc-shaped structure that mates with the metal shielding cap 22, and the end of the pressure pin 4 contacts the metal shielding cap 22 after being inserted into the recess 21.

[0020] In this embodiment, the pressure pin 4 is a grounded structure. The grounded pressure pin 4 can shield the electric field originally applied to the air gap between the insulating block 2 and the metal clamp support 3, so that the electric field is applied evenly to the insulating block 2 with better insulation performance. The metal shielding cap 22, as a grounding electrode, can effectively change the electric field distribution and avoid electric field concentration in the air gap.

[0021] Each pressure pin 4, whose end matches the recess 21, serves as a clamping structure to stably clamp the insulating block 2, ensuring uniform force on the winding coil 1 and improving the short-circuit withstand capability of the winding coil 1. This design effectively solves the problem of uneven pressure caused by different compression ratios of silicone rubber sheets in traditional structures.

[0022] Specifically, the matching accuracy between the end of the pressure nail 4 and the recess 21 of the insulating block 2 is crucial. High-precision machining, such as five-axis linkage machining, is required to ensure that the end profile tolerance of the pressure nail 4 is within ±0.01mm, thereby maximizing the contact area and avoiding local stress concentration and electric field distortion.

[0023] Specifically, it also includes an insulator 5, one end of which is inserted into the insulating block 2, and the other end of which extends into the winding coil 1.

[0024] It is worth noting that the bottom surface of the insulating block 2 is provided with a slot 23, and one end of the insulator 5 is inserted into the slot 23.

[0025] Preferably, the insulator 5 is a PET separator or an insulating tube.

[0026] By installing insulator 5, the creepage distance can be extended, making it difficult for the upper terminal of the high-voltage winding coil 1 to creep onto the insulating block 2 and cause a grounding fault. The creepage distance is positively correlated with the voltage of the high-voltage winding coil 1, and extending the creepage distance can effectively prevent discharge phenomena in polluted environments.

[0027] The embodiments of this utility model have been described in detail above with reference to the accompanying drawings, but this utility model is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of this utility model, and these variations still fall within the protection scope of this utility model.

Claims

1. A stable clamping structure for reducing partial discharge in dry-type transformers, characterized in that: This includes an insulating block, a clamping bracket, and pressure pins positioned on the upper side of the winding coil; The insulating block has a hemispherical structure with a recessed portion on the top spherical surface. The pressure pin passes through the clamping bracket and is pressed into the recessed portion. The bottom surface of the insulating block is flat and is located on the upper side of the winding coil.

2. The stabilizing clamping structure for reducing partial discharge in dry-type transformers according to claim 1, characterized in that: The recessed portion of the insulating block is provided with a metal shielding cap. The recessed portion is a hemispherical structure, and the metal shielding cap is an arc-shaped structure that fits the wall of the recessed portion.

3. The stabilizing clamping structure for reducing partial discharge in dry-type transformers according to claim 2, characterized in that: The end of the pin that is inserted into the recess has an arc-shaped structure that mates with the metal shielding cap. After the end of the pin is inserted into the recess, it comes into contact with the metal shielding cap.

4. The stabilizing clamping structure for reducing partial discharge in dry-type transformers according to claim 1, characterized in that: It also includes an insulator, one end of which is inserted into the insulating block and the other end of which extends into the winding coil.

5. The stabilizing clamping structure for reducing partial discharge in dry-type transformers according to claim 4, characterized in that: The bottom surface of the insulating block has a groove, and one end of the insulator is inserted into the groove.

6. The stabilizing clamping structure for reducing partial discharge in dry-type transformers according to claim 4, characterized in that: The insulator is a PET separator or an insulating tube.

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