Low-voltage shielding structure of mutual inductor

Abstract

The utility model discloses a mutual inductor low-voltage shielding structure which comprises a primary high-voltage end, a low-voltage shield is arranged on the outer side of the primary high-voltage end, an insulation distance is arranged between the low-voltage shield and the primary high-voltage end to prevent primary breakdown, and an installation distance is arranged between the low-voltage shield and the outer edge of a mutual inductor body to prevent primary breakdown. The low-voltage shield is provided with supporting legs, and the supporting legs are connected with the embedded hexagon nuts. By arranging the low-voltage shield on the outer side of the primary high-voltage end, partial discharge data can be effectively improved, the creepage phenomenon of the mutual inductor is solved, and stable operation of a power system is effectively guaranteed.

Description

TECHNICAL FIELD

[0001] The utility model relates to a mutual inductor technical field especially relates to a mutual inductor low voltage shielding structure. BACKGROUND

[0002] With the miniaturization of electrical equipment, mutual inductor needs stronger insulation performance in addition to meeting normal current and voltage conversion functions. During mutual inductor production and operation, high voltage field is usually too concentrated, resulting in excessive creepage or partial discharge. At this time, a low voltage shield is needed to balance the electric field distribution. In the prior art, a smooth and round high voltage shield is usually arranged at the primary end to shield some small burrs that cannot be handled at the high voltage end, so as to improve the partial discharge. This scheme is applicable to most current and voltage transformers, but is not applicable to current and voltage transformers with strong insulation performance requirements, such as integrated current transformers and current transformer brackets for insulation, therefore, it is an urgent problem to separately arrange a low voltage shield. SUMMARY

[0003] The utility model aims at solving the above technical problem, provides a mutual inductor low voltage shielding structure.

[0004] In order to realize the above technical purpose and achieve the above technical requirements, the utility model adopts the technical scheme that a mutual inductor low voltage shielding structure, including primary high voltage end, the primary high voltage end outside is provided with low voltage shield, the low voltage shield is provided with insulation distance with primary high voltage end, prevents causing primary breakdown, the low voltage shield is provided with installation distance with mutual inductor body outer edge, prevents mutual inductor creeping, be provided with support leg on the low voltage shield, the support leg is connected with the embedded hexagon nut, the embedded hexagon nut sets up in the insulation mounting plate.

[0005] Preferably, the insulation distance of the 10kV mutual inductor is greater than or equal to 10mm, the insulation distance of the 20kV mutual inductor is greater than or equal to 15mm, and the insulation distance of the 35kV mutual inductor is greater than or equal to 20mm.

[0006] Preferably, the low voltage shield is greater than 10mm away from the outer edge of the mutual inductor body.

[0007] Preferably, the low voltage shield is in the form of a closed ring and surrounds the primary high voltage end of the current transformer bracket, four support legs A are arranged around the low voltage shield, the support legs A are connected with embedded hexagon nuts A, and the embedded hexagon nuts A are arranged on the insulation mounting plate A in the middle of the current transformer bracket.

[0008] Preferably, the low-voltage shield is in the shape of a semi-enclosed box, covering the side of the primary winding of the primary high-voltage terminal of the current transformer. A support foot B is provided on one side of the low-voltage shield, and the support foot B is connected to an embedded hexagonal nut B. The embedded hexagonal nut B is set on the insulating mounting plate B in the middle of the current transformer.

[0009] Preferably, the low-voltage shield covers the top, bottom, front, back, and left side of the primary winding.

[0010] Compared with traditional structures, the advantages of this utility model are: simple structure and reasonable design. By setting a low-voltage shield on the outside of the primary high-voltage end, it can effectively improve the partial discharge data, solve the creepage phenomenon of the transformer, and effectively ensure the stable operation of the power system. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present utility model;

[0012] Figure 2 for Figure 1 Top view;

[0013] Figure 3 This is a schematic diagram of the structure of Embodiment 2 of this utility model;

[0014] Figure 4 for Figure 3 Top view;

[0015] In the diagram: 1. Current transformer bracket, 1-1. Insulating mounting plate A, 1-2. Embedded hexagonal nut A, 2. Primary high voltage terminal, 2-1. Copper terminal A, 2-2. Connecting copper rod, 2-3. Copper terminal B, 3. Low voltage shield, 4. Current transformer, 4-1. Insulator A, 4-2. Insulating mounting plate B, 4-3. Embedded hexagonal nut B, 4-4. Insulator B, 5. Primary winding, 6. Support foot A, 7. Secondary coil, 8. Support foot B. Detailed Implementation

[0016] The present invention will be further described below.

[0017] Referring to the attached drawings, a low-voltage shielding structure for a current transformer includes a primary high-voltage terminal 2. A low-voltage shield 3 is disposed outside the primary high-voltage terminal 2. The insulation distance between the low-voltage shield 3 and the primary high-voltage terminal 2 is sufficient: ≥10mm for 10kV current transformers, ≥15mm for 20kV current transformers, and ≥20mm for 35kV current transformers, to prevent primary breakdown. The distance between the low-voltage shield 3 and the outer edge of the current transformer body must be greater than 10mm; otherwise, it will shorten the external insulation creepage distance and cause current leakage in the current transformer.

[0018] Example 1: As Figures 1-2As shown, the current transformer support 1 is used as an insulating part, which requires a partial discharge amount ≤ 3 pc. The primary high-voltage end 2 penetrates through the inside of the current transformer support 1, and the primary high-voltage end 2 includes two copper terminal heads A2-1, B2-3 and a connecting copper rod 2-2. The middle part of the current transformer support 1 is provided with an insulating mounting plate A1-1, and the mounting plate is embedded with a hexagonal nut A1-2, which is used to fix the transformer 1 and the cabinet body of the switch cabinet. The embedded hexagonal nut A1-2 is at a low potential and is free in the high electric field formed by the primary high-voltage end 2, resulting in a high partial discharge amount. At this time, a low-voltage shield 3 needs to be set to balance the low-voltage electric field and improve the partial discharge.

[0019] The low-voltage shield 3 is in the form of a closed ring and surrounds the primary high-voltage end 2 of the current transformer support 1, and extends four support feet A6, which are connected with the embedded hexagonal nut A1-2.

[0020] Embodiment 2: as shown in Figures 3-4 As shown, the 35kV integrated current transformer 4 is integrated with an insulator A4-1 and an insulator B4-4 on the P1 and P2 sides of the current transformer 4, respectively. The middle part of the current transformer 4 is also provided with an insulating mounting plate B4-2, and the mounting plate B4-2 is embedded with a hexagonal nut B4-3. When the primary high-voltage end is wound in multiple turns, the outer ring of the primary winding 5 of the primary high-voltage end is smooth without an umbrella skirt to increase the creepage distance, and is close to the low-voltage end, resulting in a primary voltage creep. Therefore, a low-voltage shield 3 needs to be set to change the primary winding discharge to the withstand voltage between the high and low voltage ends inside the transformer, so as to avoid the occurrence of the creepage phenomenon during the primary power frequency withstand voltage test.

[0021] The low-voltage shield 3 is in the form of a semi-closed box and covers the primary winding 5 of the primary high-voltage end of the current transformer 4 on the upper, lower, front, rear and left sides, and the right side has a secondary coil 7, which belongs to the low-voltage end and does not need to be covered. The low-voltage shield 3 is provided with a support foot B8 on one side, which is connected with the embedded hexagonal nut B4-3.

[0022] The low-voltage shield 3 is usually made of stainless steel mesh with good electrical conductivity. The stainless steel mesh is thin and has good plasticity, and is usually used in low-voltage shields with closed shapes and has less burrs. If the low-voltage shield is in an open shape, the stainless steel mesh has poor shaping effect and needs to be increased in skeleton; or a metal plate is used, and holes are opened on the surface of the metal plate to increase the bonding force between the resin and the metal plate and avoid cracking. By setting the low-voltage shield outside the primary high-voltage end, the partial discharge data can be effectively improved, the creepage phenomenon of the transformer can be solved, and the stable operation of the power system can be effectively ensured.

[0023] The above embodiment of the utility model is only used for clearly illustrating the examples made by the utility model, but is not used for limiting the protection scope of the utility model, and all equivalent technical solutions also belong to the scope of the utility model, and the patent protection scope of the utility model should be limited by each claim.

Claims

1. A low voltage shield structure for a transformer, characterized by: The primary high voltage end (2) is provided with a low voltage shield (3) outside, an insulation distance is provided between the low voltage shield (3) and the primary high voltage end (2) to prevent causing primary breakdown, an installation distance is provided between the low voltage shield (3) and the outer edge of the transformer body to prevent transformer creeping, a supporting leg is provided on the low voltage shield (3), the supporting leg is connected with an embedded hexagon nut, and the embedded hexagon nut is arranged in an insulation mounting plate.

2. The instrument transformer low voltage shield structure of claim 1, wherein: The insulation distance of the 10kV transformer is greater than or equal to 10mm, the insulation distance of the 20kV transformer is greater than or equal to 15mm, and the insulation distance of the 35kV transformer is greater than or equal to 20mm.

3. The instrument transformer low voltage shield structure of claim 1, wherein: The distance between the low voltage shield (3) and the outer edge of the transformer body is greater than 10mm.

4. The instrument transformer low voltage shield structure of claim 1, wherein: The low voltage shield (3) is in a closed ring shape and surrounds the primary high voltage end (2) of the current transformer support (1), four supporting legs A (6) are arranged around the low voltage shield (3), the supporting legs A (6) are connected with embedded hexagon nuts A (1-2), and the embedded hexagon nuts A (1-2) are arranged on the insulation mounting plate A (1-1) in the middle of the current transformer support (1).

5. The instrument transformer low voltage shield structure of claim 1, wherein: The low voltage shield (3) is in a semi-closed box shape and covers the side of the primary winding (5) of the primary high voltage end of the current transformer (4), a supporting leg B (8) is arranged on one side of the low voltage shield (3), the supporting leg B (8) is connected with an embedded hexagon nut B (4-3), and the embedded hexagon nut B (4-3) is arranged on the insulation mounting plate B (4-2) in the middle of the current transformer (4).

6. The instrument transformer low voltage shield structure of claim 5, wherein: The low voltage shield (3) covers the upper, lower, front, rear and left side of the primary winding (5).

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