A contact arc quenching system for a circuit breaker

Abstract

A contact arc extinguishing system of a circuit breaker, comprising a contact system and an arc chamber, the contact system comprising a moving contact and a stationary contact, the moving contact comprising a short contact piece and a long contact piece, the short contact piece being provided with a moving contact point and the long contact piece being provided with a moving arc contact point, the stationary contact being provided with a stationary contact point and a stationary arc contact point, the stationary contact point corresponding to the moving contact point and the stationary arc contact point corresponding to the moving arc contact point, characterized in that during the opening operation of the moving contact, a first distance d1 between the moving contact point and the stationary contact point is greater than a second distance d2 between the moving arc contact point and the stationary arc contact point. Advantage: the distance between the moving contact point and the stationary contact point is greater than the distance between the moving arc contact point and the stationary arc contact point by setting the limiting structure, preventing the breakdown on the main contact point; the distance between the moving arc contact point and the stationary arc contact point is greater than the distance of the arc inlet, so that the possibility of breakdown on the main contact point is smaller.

Description

Technical Field

[0001] This invention belongs to the field of low-voltage electrical technology, specifically relating to an arc-extinguishing system for the contacts of a circuit breaker. Background Technology

[0002] Air circuit breakers, as important power distribution equipment, are connected to the power grid to protect downstream loads from fault current damage. However, with the development of new energy sources, the application of DC circuit breakers is increasing, and voltage requirements are constantly rising. This places new demands on existing air circuit breakers.

[0003] Large-scale air circuit breakers typically employ a multi-contact structure, including main contacts and arc contacts. The main contacts carry current, while the arc contacts, while carrying current, also break it. Structurally, the arc contacts close before the main contacts open, and during circuit breaker breaking, the arc is generated only on the arc contacts. To facilitate better breaking, the arc contacts often extend into the arc-extinguishing chamber, or even into narrow gaps. During breaking, the arc needs to be maintained on the arc contacts to facilitate its extinguishing. However, because complete isolation between the arc contacts and main contacts is difficult to achieve, the high-temperature gas generated by the arc on the arc contacts can flow between the active and stationary contacts. When the circuit breaker breaks, during the contact opening process, the arc voltage can reach a very high value, which can easily cause the main and stationary contacts to break down due to excessive electric field strength, generating an arc. This adversely affects the breaking process and may even lead to breaking failure. Summary of the Invention

[0004] The objective of this invention is to provide a contact arc extinguishing system for a circuit breaker, which, during the opening process of the moving contact relative to the stationary contact, ensures that the distance between the moving contact and the stationary contact is greater than the distance between the moving arc contact and the stationary arc contact through the setting of a limiting structure, thereby preventing breakdown at the main contacts.

[0005] The objective of this invention is achieved as follows: a contact arc-extinguishing system for a circuit breaker, comprising a contact system and an arc-extinguishing chamber, wherein the contact system includes a moving contact and a stationary contact, the moving contact comprising a short contact piece and a long contact piece, the short contact piece having a moving contact point and the long contact piece having a moving arc contact point, the stationary contact having a stationary contact point and a stationary arc contact point, the stationary contact point corresponding to the moving contact point, and the stationary arc contact point corresponding to the moving arc contact point, wherein during the opening action of the moving contact, a first distance d1 between the moving contact point and the stationary contact point is greater than a second distance d2 between the moving arc contact point and the stationary arc contact point.

[0006] In a specific embodiment of the present invention, the arc-extinguishing chamber includes grid plates, which are arranged in a parallel array. At both ends of the array direction of the grid plates, there are stationary arc-leading plates and moving arc-leading plates. The stationary arc-leading plates and moving arc-leading plates extend towards one side of the contact system and approach each other to form the arc-entry port of the arc-extinguishing chamber. When the moving contact is in the open position, the second distance d2 between the moving arc contact and the stationary arc contact is greater than the distance d3 of the arc-entry port.

[0007] In another specific embodiment of the present invention, when the moving contact is in the open position, the first distance d1 between the moving contact and the stationary contact is greater than the second distance d2 between the moving arc contact and the stationary arc contact.

[0008] In another specific embodiment of the present invention, the moving contact further includes a contact support and a rotating shaft. The short contact piece and the long contact piece are rotatably mounted on the contact support via the rotating shaft. The contact support is provided with an abutting surface and an abutting recess is formed on the abutting surface. During the opening process of the moving contact, the short contact piece abuts against the abutting surface, and the long contact piece abuts against the abutting recess.

[0009] In another specific embodiment of the present invention, the outer edge of the bottom of the short contact piece of the short contact piece contacts the abutting surface, and the outer edge of the bottom of the long contact piece of the long contact piece contacts the abutting recess.

[0010] In another specific embodiment of the present invention, the contact support has a rotation center, and the line connecting the moving contact and the rotation center and the line connecting the moving arc contact and the rotation center form an angle α, which is greater than 3º.

[0011] In a further specific embodiment of the present invention, the line connecting the moving contact and the rotation center and the line connecting the moving arc contact and the rotation center form an angle α, wherein the angle α is greater than 5º.

[0012] In a further specific embodiment of the invention, the moving contact has a contact spring mounted on the contact support, with one end of the contact spring abutting against the contact support and the other end abutting against the short contact piece and the long contact piece.

[0013] In yet another specific embodiment of the present invention, the moving contact is inserted into the interior of the arc-extinguishing chamber, while the moving contact is located on the outside of the arc-extinguishing chamber.

[0014] In yet another specific embodiment of the present invention, the long contact piece is integrally formed with the moving arc contact, and / or the stationary contact is integrally formed with the stationary arc contact.

[0015] The present invention achieves the following beneficial effects due to the above-described structure: during the opening of the moving contact relative to the stationary contact, the setting of the limiting structure ensures that the distance between the moving contact and the stationary contact is greater than the distance between the moving arc contact and the stationary arc contact, thereby preventing breakdown at the main contact; furthermore, since the distance between the moving arc contact and the stationary arc contact is greater than the spacing of the arc inlet, the possibility of breakdown at the main contact is even smaller. Attached Figure Description

[0016] Figure 1 This is a diagram showing the fit between the contact system and the arc-extinguishing chamber involved in the present invention; Figure 2 This is a schematic diagram of the contact system of the present invention in the closed state; Figure 3 This is a schematic diagram of the contact system involved in the present invention during the opening process; Figure 4 This is a schematic diagram of the contact system of the present invention when it is in the open position; Figure 5 This is a schematic diagram illustrating the contact support and the abutment cooperation between the long contact piece and the short contact piece involved in the present invention; Figure 6 This is a schematic diagram of the contact support involved in the present invention; Figure 7 This is a schematic diagram of the contact system carrying the aforementioned rotating center when it is in the open position, as per the present invention. Detailed Implementation

[0017] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the description of the embodiments is not a limitation on the technical solution. Any formal but not substantive changes made based on the concept of the present invention should be considered within the scope of protection of the present invention.

[0018] In the following description, all directional or orientational concepts involving up, down, left, right, front, and back are based on the positions shown in the corresponding figures, and therefore should not be construed as a special limitation on the technical solutions provided by this invention.

[0019] Please see Figure 1 , Figure 1This is a schematic diagram of the arc-extinguishing system. It includes a contact system and an arc-extinguishing chamber 3. The contact system includes a moving contact 1 and a stationary contact 2. The stationary contact 2 is fixed, while the moving contact 1 can move relative to the stationary contact 2, thereby achieving contact or separation between the two. Typically, the moving contact 1 is oscillating; that is, after oscillating, the moving contact 1 makes contact or separates from the stationary contact. Therefore, the circuit breaker has an open state and a closed state. When the contact system is closed, the moving contact 1 and the stationary contact 2 are in the contact position, and the circuit breaker is in the closed state. When the contact system is open, the moving contact 1 and the stationary contact 2 are in the separated position, and the circuit breaker is in the open state.

[0020] The moving contact 1 includes a short contact piece 11 and a long contact piece 12. A moving contact 111 is provided on the short contact piece 11, while a moving arc contact 121 is provided on the long contact piece 12. The moving arc contact 121 extends into the arc-extinguishing chamber 3, while the moving contact 111 is located outside the arc-extinguishing chamber 3. With this arrangement, when an arc is generated on the moving arc contact 121, the arc is already inside the arc-extinguishing chamber 3.

[0021] The stationary contact 2 is provided with a stationary contact 21 and a stationary arc contact 22, wherein the stationary contact 21 corresponds to the moving contact 111, and the stationary arc contact 22 corresponds to the moving arc contact 121. That is, the stationary contact 21 and the moving contact 111 are in contact or separate; and the stationary arc contact 22 and the moving arc contact 121 are in contact or separate.

[0022] See you later Figure 1 The arc-extinguishing chamber 3 includes grid plates 31, which are arranged in a parallel array. At both ends of the array direction of the grid plates 31 are stationary arc-drawing plates 32 and moving arc-drawing plates 33. The stationary arc-drawing plates 32 and moving arc-drawing plates 33 extend towards one side of the contact system and approach each other, forming the arc inlet of the arc-extinguishing chamber 3 at the closest point between the moving arc-drawing plates 33 and the stationary arc-drawing plates 32.

[0023] The extended end of the stationary arc-drawing plate 32 is fixed to the end face of the stationary contact 2 facing the contact system. Typically, the two are fixed by welding or screws.

[0024] Please see Figure 2 , Figure 2 This diagram illustrates the contact system in the closed state, meaning that the moving contact 1 and the stationary contact 2 are in the fully engaged contact position. At this time, the moving contact 111 is in contact with the stationary contact 21, and simultaneously, the moving arc contact 121 is in contact with the stationary arc contact 22. The circuit breaker is in the closed state at this time.

[0025] Please see Figure 3 as well as Figures 5 to 6 The moving contact 1 further includes a contact support 100, and the short contact piece 11 and the long contact piece 12 are rotatably mounted on the contact support 100 via a rotating shaft (not shown in the figure). Typically, a pair of side plates (not shown in the figure) are provided on both sides of the contact support 100. The pair of side plates are fixed to both sides of the contact support 100, and the rotating shaft is mounted on the pair of side plates. This mounting relationship can be understood as the short contact piece 11 and the long contact piece 12 being indirectly rotatably mounted on the contact support 100.

[0026] The contact support 100 is provided with an abutment surface 102, and an abutment recess 101 is formed on the abutment surface 102.

[0027] The short contact piece 11 forms a lever with the rotation axis as the rotation center. The moving contact 111 is located on one swinging side of the short contact piece 11, while the bottom of the short contact piece 11 is located on the other swinging side. During the opening process of the moving contact 1, the outer edge of the bottom of the short contact piece 11 contacts the abutment surface 102. At this time, the abutment surface 102 restricts the rotation of the short contact piece 11 relative to the contact support 100. The rotation of the short contact piece 11 relative to the contact support 100, and the travel reflected on the moving contact 111, is the overtravel of the short contact piece 11. The moving contact 1 has a contact spring (not shown in the figure) mounted on the contact support 100, with one end of the contact spring abutting against the contact support 100 and the other end abutting against the short contact piece 11 and the long contact piece 12.

[0028] The long contact piece 12 forms a lever with the rotating shaft as its rotation center. The moving arc contact 121 is located on one swinging side of the long contact piece 12, while the bottom of the long contact piece 12 is located on the other swinging side. During the opening of the moving contact 1, the outer edge of the bottom of the long contact piece 12 contacts the abutment recess 101, which restricts the rotation of the long contact piece 12 relative to the contact support 100. The rotation of the long contact piece 12 relative to the contact support 100, reflected in the travel on the moving arc contact 121, is the overtravel of the long contact piece 12.

[0029] Please see Figure 3During the opening process of the moving contact 1 relative to the stationary contact 2, the contact spring (not shown in the figure) drives the short contact piece 11 and the long contact piece 12 to rotate relative to the contact support 100. At this time, the short contact piece 11 abuts against the abutting surface 102, while the long contact piece 12 abuts against the abutting recess 101. The applicant sets the height difference between the abutting recess 101 and the abutting surface 102 so that the angles of the long contact piece 12 and the short contact piece 11 relative to the contact support 100 are different, thereby making the first distance d1 between the moving contact 111 and the stationary contact 21 greater than the second distance d2 between the moving arc contact 121 and the stationary arc contact 22.

[0030] This difference in distance means that when an arc breaks down between the moving contact 1 and the stationary contact 2, it preferentially occurs between the moving arc contact 121 and the stationary arc contact 22.

[0031] Please see Figure 4 The moving contact 1 is in the fully open state. At this time, the moving contact 1 has also swung to its position and is stationary relative to the stationary contact 2. The first distance d1 between the moving contact 111 and the stationary contact 21 is greater than the second distance d2 between the moving arc contact 121 and the stationary arc contact 22. The distance d2 between the moving arc contact 121 and the stationary arc contact 22 is greater than the arc inlet spacing d3. At this time, the priority order of breakdown is: arc inlet, the distance between the moving arc contact 121 and the stationary arc contact 22, and the distance between the moving contact 111 and the stationary contact 21. This arrangement further prevents breakdown at the moving contact 111 and the stationary contact 21.

[0032] Please see Figure 7 This is a schematic diagram of the contact system in the open position, showing the rotation center 200 of the moving contact 1, i.e., the moving contact 1 rotates around the rotation center 200. In other words, the contact support 100 has a rotation center 200, and the contact support 100 rotates around the rotation center 200.

[0033] In fact, the purpose of the applicant's setting of the height difference between the abutment recess 101 and the abutment surface 102 mentioned above is to adjust the angle between the line connecting the moving contact 111 and the rotation center 200, and the line connecting the moving arc contact 121 and the rotation center 200.

[0034] The applicant has done a lot of design work regarding the angle between the line connecting the moving contact 111 and the rotation center 200, and the line connecting the moving arc contact 121 and the rotation center 200. Specifically, when the included angle α is greater than 3º, the aforementioned distance difference can be guaranteed. Preferably, it is greater than 5º for better results.

[0035] Regarding the aforementioned setting of the height difference between the abutment recess 101 and the abutment surface 102, in terms of equivalent technical means, it can be achieved by setting the outer edges of the bottom of the short contact piece 11 and the outer edges of the bottom of the long contact piece 12, since the two are in abutment fit. Specifically, adjusting the difference between the distance between the outer edge of the bottom of the short contact piece and the rotation axis and the distance between the outer edge of the bottom of the long contact piece and the rotation axis is reflected in the aforementioned included angle α.

[0036] For those skilled in the art, the long contact piece 12 and the moving arc contact 121 are integrally formed, and the moving arc contact 121 is a contact portion on the long contact piece 12. Similarly, the stationary contact 2 and the stationary arc contact 22 are integrally formed, and the stationary arc contact 22 is a contact portion on the stationary contact 2.

Claims

1. A contact arc-extinguishing system for a circuit breaker, comprising a contact system and an arc-extinguishing chamber (3), wherein the contact system comprises a moving contact (1) and a stationary contact (2), the moving contact (1) comprising a short contact piece (11) and a long contact piece (12), wherein a moving contact (111) is provided on the short contact piece (11), and a moving arc contact (121) is provided on the long contact piece (12), wherein a stationary contact (21) and a stationary arc contact (22) are provided on the stationary contact (22), wherein the stationary contact (21) corresponds to the moving contact (111), and the stationary arc contact (22) corresponds to the moving arc contact (121), characterized in that: During the opening operation of the moving contact (1), the first distance d1 between the moving contact (111) and the stationary contact (21) is greater than the second distance d2 between the moving arc contact (121) and the stationary arc contact (22). The arc-extinguishing chamber (3) includes grid plates (31), which are arranged in a parallel array. At both ends of the array direction of the grid plates (31), there are stationary arc-leading plates (32) and moving arc-leading plates (33). The plates (33) extend to one side of the contact system and move closer together to form the arc inlet of the arc-extinguishing chamber (3); when the moving contact (1) is in the open position, the second distance d2 between the moving arc contact (121) and the stationary arc contact (22) is greater than the distance d3 of the arc inlet, and the first distance d1 between the moving contact (111) and the stationary contact (21) is greater than the second distance d2 between the moving arc contact (121) and the stationary arc contact (22).

2. The contact arc extinguishing system of a circuit breaker according to claim 1, characterized in that: The moving contact (1) further includes a contact support (100) and a rotating shaft. The short contact piece (11) and the long contact piece (12) are rotatably mounted on the contact support (100) via the rotating shaft. The contact support (100) is provided with an abutment surface (102) and an abutment recess (101) is formed on the abutment surface (102). During the opening process of the moving contact (1), the short contact piece (11) abuts against the abutment surface (102), and the long contact piece (12) abuts against the abutment recess (101).

3. The contact arc extinguishing system of a circuit breaker according to claim 2, characterized in that: The outer edge of the bottom of the short contact piece (11) contacts the abutting surface (102), and the outer edge of the bottom of the long contact piece (12) contacts the abutting recess (101).

4. The contact arc extinguishing system of a circuit breaker according to claim 2, characterized in that: The contact support (100) has a rotation center (200), and the line connecting the moving contact (111) and the rotation center (200) and the line connecting the moving arc contact (121) and the rotation center (200) form an angle α, which is greater than 3º.

5. The contact arc extinguishing system of a circuit breaker according to claim 4, characterized in that: The line connecting the moving contact (111) and the rotation center (200) and the line connecting the moving arc contact (121) and the rotation center (200) form an angle α, which is greater than 5º.

6. The contact arc extinguishing system of a circuit breaker according to claim 2, characterized in that: The moving contact (1) has a contact spring mounted on the contact support (100), with one end of the contact spring abutting against the contact support (100) and the other end abutting against the short contact piece (11) and the long contact piece (12).

7. The contact arc extinguishing system of a circuit breaker according to claim 1, characterized in that: The moving contact (121) extends into the arc-extinguishing chamber (3), while the moving contact (111) is located on the outside of the arc-extinguishing chamber (3).

8. The contact arc extinguishing system of a circuit breaker according to claim 1, characterized in that: The long contact piece (12) is integrally formed with the moving arc contact (121), and / or the stationary contact (2) is integrally formed with the stationary arc contact (22).

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