A contact assembly for high-voltage switchgear

Abstract

The present invention belongs to the technical field of switchgear and specifically discloses a contact assembly for high-voltage switchgear, comprising a fixed contact conductor, a shielding cover, an electrical contact, and a contact conductor, wherein the fixed contact conductor is electrically connected to the contact conductor via the electrical contact; the shielding cover is fixed to the outside of the electrical contact, and heat dissipation holes are provided on the circumferential surface of the shielding cover in a circumferential direction; a plurality of isolation blocks are provided on the inner wall of the shielding cover in a circumferential array, the isolation blocks and the heat dissipation holes being staggered, and the area formed by two adjacent isolation blocks is used to assemble the contact finger assembly of the electrical contact. By providing heat dissipation holes on the shielding cover, heat generated at the electrical contact point can be quickly dissipated, and energy generated at the contact point can be promptly and effectively transferred out. The invention is particularly suitable for contact assemblies of high-current switchgear of 6300A and above; the isolation blocks can prevent heat from being transferred and affecting each other between each group of contact assemblies, while also playing a certain role in absorbing heat and quickly dissipating heat.

Description

Technical Field

[0001] The present invention belongs to the technical field of switchgear, and in particular relates to a contact assembly for high-voltage switchgear. Background Art

[0002] In traditional switchgear, electrical contact between conductors is often achieved through contact connections. Contact structures vary, including self-powered, plum blossom, and finger-type contacts. A shielding cover is placed outside the contact structure to shield the contact structure, improve the electric field, and enhance insulation. Because traditional switchgear requires relatively low current-carrying capacity, it can generally meet user needs.

[0003] In recent years, with the rapid development of power grid construction and the demand for an environmentally friendly society, user requirements for miniaturized, high-parameter, and large-capacity switchgear have become increasingly stringent. Furthermore, with the implementation of major engineering projects such as large-scale hydropower projects and urban and rural power grid reconstruction, transmission networks are continuously evolving towards higher voltages, longer distances, larger capacities, and smaller sizes. Consequently, the current-carrying capacity requirements for switchgear are also gradually increasing. Pumped-storage switchgear, in particular, has low rated voltages and high current-carrying capacities, typically exceeding 6300A. This makes the heat dissipation structure of the main conductive circuit particularly critical. To improve the current-carrying capacity of conventional switchgear, one approach involves changing the material of the inserted conductor, increasing costs; another involves optimizing and improving the electrical contact structure, increasing the conductor size, and increasing the number of contact points, which increases the size of the switchgear. Third, increasing the number of contact points increases the electrical contact pressure (i.e., the clamping force), reducing contact resistance. However, if the contact conductor is used as a movable part, this increases the operating work of the mechanism. In summary, the above methods are currently mainly used to improve the current carrying capacity, but none of them meet the user's requirements for miniaturization, low cost, high reliability and green environmental protection of switchgear. Summary of the Invention

[0004] In order to overcome the defects of the above-mentioned prior art, the purpose of the present invention is to provide a contact assembly for high-voltage switchgear, which solves the problem that the current technical means adopted to improve the current-carrying capacity do not meet the user's requirements for miniaturization, low cost, high reliability and green environmental protection of switchgear.

[0005] The present invention is achieved through the following technical solutions:

[0006] A contact assembly for a high-voltage switchgear comprises a fixed contact conductor, a shield, an electrical contact and a contact conductor, wherein the fixed contact conductor is electrically connected to the contact conductor via the electrical contact;

[0007] The shielding cover is fixed on the outside of the electrical contact, and a plurality of heat dissipation holes are opened on the circumferential surface of the shielding cover along the circumferential direction;

[0008] A plurality of isolation blocks arranged in a circumferential array are provided on the inner wall of the shielding cover. The isolation blocks are staggered with the heat dissipation holes. The area formed by two adjacent isolation blocks is used for assembling the contact finger assembly of the electrical contact.

[0009] Furthermore, the heat dissipation hole is an elongated hole, and the length direction of the elongated hole is arranged parallel to the axis of the electrical contact.

[0010] Furthermore, the elongated hole includes a rectangular hole and two semicircular holes connected to both ends of the rectangular hole.

[0011] Furthermore, the length of the heat dissipation hole is less than or equal to half the length of the electrical contact.

[0012] Furthermore, the distance between adjacent edges of adjacent heat dissipation holes is greater than or equal to 1.2 times the thickness of the shielding cover wall.

[0013] Furthermore, one end of the shielding cover close to the contact conductor side adopts an inwardly turned edge structure.

[0014] Furthermore, the distance between the fixed ends of two adjacent isolation blocks is recorded as H1, and the distance between the free ends of two adjacent isolation blocks is recorded as H2, and H1-H2≤2.5mm.

[0015] Furthermore, one end of the electrical contact is electrically connected to the fixed contact conductor through a plurality of first electrical contact points, and the other end of the electrical contact is electrically connected to the contact conductor through a plurality of second electrical contact points.

[0016] Furthermore, the heat dissipation hole is arranged in a middle position between the first electrical contact point and the second electrical contact point.

[0017] Furthermore, the contact conductor and the electrical contact are in a fixed electrical contact or a movable electrical contact manner.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects:

[0019] The present invention discloses a contact assembly for high-voltage switchgear. By providing heat dissipation holes on a shielding cover, the heat generated at the electrical contact point can be quickly dissipated. This can avoid the traditional shielding that traps the heat and can only dissipate the heat outward through the shielding cover material itself, which has low heat dissipation efficiency and cannot meet the current carrying capacity requirements of the high current. After the heat dissipation holes are provided, the heat conduction mode here is mainly natural convection heat transfer, and the efficiency of convection heat transfer is higher than that of heat transfer and heat radiation through the material itself. Therefore, the energy generated by the contact point can be timely and effectively transferred out, meeting the needs of large-capacity switchgear. The present invention improves the current carrying capacity by improving the heat transfer capacity and arrangement structure of the electrical contact part, meeting the requirements of miniaturization and low cost of switchgear, meeting the requirements of current carrying capacity of 6300A and above, and is particularly suitable for contact assemblies of high-current switchgear of 6300A and above. An isolation block is provided inside the shielding cover, which can prevent the heat between each group of contact assemblies from being transferred and affecting each other, and at the same time plays a certain role in heat absorption and rapid heat dissipation.

[0020] Furthermore, the heat dissipation hole is a long strip hole, the horizontal axis direction of which is arranged horizontally with the axis of the shielding cover and is consistent with the direction of the current path when carrying current, which is conducive to rapid heat exchange and rapid heat dissipation.

[0021] Furthermore, the elongated hole includes a rectangular hole and two semicircular holes connected to both ends of the rectangular hole. Compared with the short hole, it can prevent heat from accumulating around the rectangular hole during the heat dissipation process, which is more conducive to heat dissipation and can ensure the uniformity of the electric field on the shielding cover.

[0022] Furthermore, after research and design, the length of the heat dissipation hole is no more than half the length of the electrical contact, and the distance between two adjacent edges of adjacent heat dissipation holes is no less than 1.2 times the thickness of the shielding cover wall, so as not to affect the overall strength of the shielding cover.

[0023] Furthermore, one end of the shielding cover close to the contact conductor side adopts a tail flange structure, which can fix one end of the electrical contact.

[0024] Furthermore, the difference between the assembly dimensions H1 and H2 of the electrical contact finger assembly is not greater than 2.5 mm. If the gap is too large, the spacing between the electrical contact finger pieces will be too large after assembly, which will cause the electrical contact to tilt excessively, and the electrical contact point will have poor contact with the contact conductor, resulting in increased resistance and rapid heating. At the same time, when the contact conductor serves as a movable electrical contact structure, friction increases, and metal particles are easily generated, causing discharge, which cannot ensure the safe and reliable operation of the switchgear.

[0025] Furthermore, when the contact conductor is a movable contact structure, the operating work requirements of the mechanism change less, which can effectively improve the safe and reliable operation of the product and meet the requirements of miniaturization, high parameters, low cost and high reliability of the switch equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the external structure of a contact assembly for a high-voltage switchgear according to the present invention;

[0027] Figure 2 This is a schematic diagram of the internal structure of a contact assembly for a high-voltage switchgear according to the present invention;

[0028] Figure 3 It is a schematic structural diagram of the shielding cover of the present invention;

[0029] Figure 4 for Figure 3 Schematic diagram of the cross-sectional structure;

[0030] Figure 5 for Figure 3 Schematic diagram of the longitudinal section structure;

[0031] Figure 6 It is a schematic diagram of the assembly structure of the contact components and the shielding cover of the present invention.

[0032] Among them: 1 is the fixed contact conductor, 2 is the shielding cover, 3 is the first electrical contact point, 4 is the heat dissipation hole, 5 is the electrical contact, 6 is the second electrical contact point, 7 is the contact conductor, 8 is the isolation block, 9 is the screw hole, and 10 is the fixed end of the electrical contact. DETAILED DESCRIPTION

[0033] The present invention is described in further detail below with reference to the accompanying drawings:

[0034] like Figures 1 to 3 As shown, the present invention discloses a contact assembly for large-capacity high-voltage switchgear, including a fixed contact conductor 1, a shielding cover 2, an electrical contact 5 and a contact conductor 7, wherein the fixed contact conductor 1 is electrically connected to the contact conductor 7 through the electrical contact 5; the shielding cover 2 is fixed to the outside of the electrical contact 5, and heat dissipation holes 4 are arranged on the circumferential surface of the shielding cover 2 in the circumferential direction.

[0035] The fixed contact conductor 1, electrical contact 5, and contact conductor 7 form a main circuit through electrical contact points, i.e., a main circuit conductive path, which carries current. Specifically, one end of the electrical contact 5 is electrically connected to the fixed contact conductor 1 via a plurality of first electrical contact points 3, and the other end of the electrical contact 5 is electrically connected to the contact conductor 7 via a plurality of second electrical contact points 6.

[0036] The electric contact 5 is connected to the fixed contact conductor 1 by threaded fixing, screw fixing or fixing with a shielding cover 2 . At the same time, the electric contact 5 is connected to the fixed contact conductor 1 to form a first electric contact point 3 .

[0037] The shielding cover 2 is connected to the fixed contact conductor 1 to improve the electric field of the electric contact 5. The shielding cover 2 can be connected to the fixed contact conductor 1 by screw fixing, thread connection and hot extrusion.

[0038] The shielding cover 2 can be processed by an integral spinning process, a casting process or a machining process; heat dissipation holes 4 are evenly opened along the circumferential direction on the circumferential surface of the shielding cover 2. The main structure of the shielding cover 2 remains unchanged, and the arrangement of the heat dissipation holes 4 will not affect the surface field strength of the electrical contact 5.

[0039] The heat dissipation holes 4 are arranged parallel to the electrical contacts 5 , the fixed contact conductors 1 , the contact conductors 7 and the like along the axis.

[0040] The electrical contacts 5 mainly include self-powered contacts, plum blossom contacts, and finger contacts.

[0041] The size and shape of the heat dissipation holes 4 are related to the electrical contacts 5. For finger-type contacts, due to the close contact between the fingers, heat dissipation holes 4 are arranged in groups of 5 to 8, with each group of fingers forming a group. For self-powered and plum blossom contacts, a heat dissipation hole 4 is placed approximately midway between two fingers, with the heat dissipation holes positioned intersecting the contact fingers. This allows heat from the electrical contacts to be quickly transferred through the heat dissipation holes 4 when carrying current, exchanging heat with the cold air outside, thereby reducing the temperature rise of the electrical contacts and meeting the temperature rise requirements specified in the standard.

[0042] The heat dissipation hole 4 is a long strip hole, the horizontal axis direction of which is arranged horizontally with the axis of the shielding cover 2 and is consistent with the direction of the current path when carrying current, which is conducive to rapid heat exchange. The heat dissipation hole 4 is basically arranged in the middle position between the first electrical contact point 3 and the second electrical contact point 6.

[0043] More preferably, after design research, it is concluded that the length of the heat dissipation hole 4 is no more than half the length of the electrical contact 5; the distance between two adjacent edges of adjacent heat dissipation holes 4 cannot be less than 1.2 times the wall thickness of the shielding cover 2, so as not to affect the overall strength of the shielding cover 2.

[0044] like Figure 3As shown, the heat dissipation holes 4 are generally a circle, and the center line of the heat dissipation holes on the circle is a circle, which can basically reduce the heat generated at the electrical contact point to meet the temperature rise value requirements specified in the standard. However, for large currents of 6300A and above, due to the large current, more heat is generated. In order to dissipate heat quickly, the heat dissipation holes 4 can be multiple circles. The size of the heat dissipation holes 4 is determined according to the specific structural dimensions, so that the heat generated at the electrical contact point can be dissipated more quickly along the heat dissipation holes 4 and exchange heat with the external cold gas to meet the requirements of large current.

[0045] Heat dissipation holes 4 are provided on the shielding cover 2. According to the path of the main circuit current, the heat conduction mode of the switchgear when carrying current is changed, so that natural convection conduction plays a major role in the heat conduction process, which can effectively improve the heat transfer efficiency and transfer the generated heat to the outside of the high-voltage switchgear in a timely manner.

[0046] Contact conductor 7 can be a fixed electrical contact structure or a movable electrical contact structure, with opening and closing operations performed via contact conductor 7. The movable contact structure minimizes the operating power requirements of the mechanism, effectively improving the product's safe and reliable operation and meeting the requirements for miniaturized switchgear, high parameters, low cost, and high reliability.

[0047] like Figure 3 As shown, the long strip hole includes a rectangular hole and two semicircular holes connected to the two ends of the rectangular hole. The two sides are semicircular holes, and the corners are rounded during the processing. The semicircular holes on the two sides can prevent heat from accumulating around the rectangular hole during the heat dissipation process compared with the short holes, which is more conducive to heat dissipation and can ensure the uniformity of the electric field on the shielding cover.

[0048] Better, if Figure 3 As shown, the inner wall of the shielding case 2 is provided with a plurality of isolation blocks 8 arranged in a circumferential array. The isolation blocks 8 are staggered with the heat dissipation holes, and the area formed by two adjacent isolation blocks 8 is used to assemble the contact finger assemblies of the electrical contacts. The isolation blocks 8 are used to separate each group of electrical contact finger assemblies. During high-current testing, they can prevent heat transfer and mutual influence between the groups of electrical contact finger assemblies, thereby avoiding excessive heat concentration. At the same time, the isolation blocks 8 also play a certain role in absorbing heat and quickly dissipating heat, which is more conducive to the application of switchgear under high current.

[0049] like Figure 6 As shown, the electrical contacts 5 are grouped into 5-10 pieces, and each group is isolated by an electrical contact isolation block 8. This can ensure sufficient clamping force and relative heat dissipation between the electrical contacts 5. Relevant tests have verified that if there are too few, the clamping force is too small, and if there are too many, the heat dissipation effect is poor and cannot meet the requirements of large current.

[0050] like Figure 4 As shown, the distance between the fixed ends of two adjacent isolation blocks 8 is recorded as H1, and the distance between the free ends of two adjacent isolation blocks 8 is recorded as H2. The electrical contacts 5 are assembled in the middle of two adjacent isolation blocks 8 in groups of 5-10 pieces, where H1-H2≤2.5mm. If the gap is too large, the spacing between the pieces of the electrical contact finger assembly will be too large after assembly, which will cause the electrical contacts 5 to tilt excessively. The second electrical contact point 6 will change from line contact to point contact with the contact conductor 7. The poor contact increases the resistance and heats up quickly. At the same time, when the contact conductor 7 is used as a movable electrical contact head structure, the friction increases, which easily generates metal particles and causes discharge, making it impossible to ensure the safe and reliable operation of the switchgear.

[0051] like Figure 5 As shown, the fixed end 10 of the electrical contact close to the contact conductor 7 adopts an inward-turned structure, which is used to fix one end of the electrical contact 5; the number of screw holes 9 is the same as the number of each group of electrical contacts 5. After each group of electrical contacts 5 is assembled with the shielding cover, the screw holes 9 are used to assemble with the fixed contact conductor 1.

[0052] In summary, the present invention provides a contact assembly for large-capacity high-voltage switchgear, which can quickly dissipate the heat generated at the electrical contact point by opening a heat dissipation hole 4 on the shielding cover 2, and can avoid the traditional shielding from covering the heat, and can only dissipate heat outward through the shielding cover 2 material itself. Its heat dissipation efficiency is low and cannot meet its current carrying capacity requirements at high currents. After the heat dissipation hole 4 is opened, the heat conduction method here is mainly natural convection heat transfer, and the efficiency of convection heat transfer is higher than that of heat transfer and heat radiation through the material itself. Therefore, the energy generated by the contact point can be transmitted out in a timely and effective manner; at the same time, an isolation block 8 is used to isolate the adjacent electrical contact finger assemblies, which can prevent heat from being concentrated in the middle, and the isolation block 8 plays the role of absorbing heat and quickly dissipating heat, meeting the needs of large-capacity switchgear, and is particularly suitable for contact assemblies of large current switchgear of 6300A and above.

Claims

1. A contact assembly for high-voltage switchgear, characterized in that: It comprises a fixed contact conductor (1), a shield (2), an electrical contact (5) and a contact conductor (7), wherein the fixed contact conductor (1) is electrically connected to the contact conductor (7) via the electrical contact (5); The shielding cover (2) is fixed on the outside of the electrical contact (5), and a plurality of heat dissipation holes (4) are provided on the circumferential surface of the shielding cover (2) along the circumferential direction; A plurality of isolation blocks (8) arranged in a circumferential array are provided on the inner wall of the shielding cover (2), the isolation blocks (8) and the heat dissipation holes (4) are arranged in an alternating manner, and the area formed by two adjacent isolation blocks (8) is used to assemble the contact finger assembly of the electric contact (5); The heat dissipation hole (4) is a long strip hole, and the length direction of the long strip hole is arranged parallel to the axis of the electric contact (5); The long strip hole includes a rectangular hole and two semicircular holes connected to both ends of the rectangular hole; The length of the heat dissipation hole (4) is less than or equal to half the length of the electrical contact (5); The distance between adjacent edges of adjacent heat dissipation holes (4) is greater than or equal to 1.2 times the wall thickness of the shielding cover (2); The distance between the fixed ends of two adjacent isolation blocks (8) is recorded as H1, and the distance between the free ends of two adjacent isolation blocks (8) is recorded as H2, H1-H2≤2.5mm; One end of the electric contact (5) is electrically connected to the fixed contact conductor (1) through a plurality of first electric contact points (3), and the other end of the electric contact (5) is electrically connected to the contact conductor (7) through a plurality of second electric contact points (6); The heat dissipation hole (4) is arranged at a middle position between the first electrical contact point (3) and the second electrical contact point (6).

2. The contact assembly for high-voltage switchgear according to claim 1, characterized in that: One end of the shielding cover (2) close to the contact conductor (7) adopts an inwardly turned edge structure.

3. The contact assembly for high-voltage switchgear according to claim 1, characterized in that: The contact conductor (7) and the electric contact (5) are in a fixed electric contact or a movable electric contact manner.

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