A closing resistor contact assembly of a circuit breaker and a circuit breaker

Abstract

The application relates to a closing resistor contact assembly of a circuit breaker and the circuit breaker, the circuit breaker comprising an arc extinguishing chamber, a main circuit and a resistor circuit being connected in parallel in the arc extinguishing chamber, the main circuit comprising a main circuit static contact and a main circuit dynamic contact, the resistor circuit comprising a closing resistor static contact assembly, a closing resistor dynamic contact assembly and a closing resistor, the closing resistor static contact assembly and the closing resistor dynamic contact assembly each comprising a contact rod and a contact, the end of the contact rod being provided with a threaded hole, the contact comprising a contact body and an external thread segment matched with the threaded hole, a pre-tightening piece being press-fitted between the contact and the contact rod, and an outer shield of the contact rod being provided with a shielding cover; a groove is arranged on the contact rod, the threaded hole being arranged on the groove bottom, a protrusion matched with the groove being arranged between the contact body and the external thread segment of the contact, the pre-tightening piece being press-fitted between the groove bottom and the protrusion, and the shielding cover being sleeved outside the protrusion and being pressed on the end face of the contact rod by the contact.

Description

Technical Field

[0001] This invention relates to the field of circuit breakers, and more specifically to a closing resistor contact assembly for a circuit breaker and a circuit breaker. Background Technology

[0002] Ultra-high voltage circuit breakers with closing resistors include a main circuit and a resistor circuit connected in parallel. The main circuit includes a stationary contact and a moving contact. The resistor circuit includes a stationary contact assembly, a moving contact assembly, and a closing resistor. During the closing process, the stationary and moving contact assemblies connect before the moving and stationary contacts of the main circuit. This converts the instantaneous overcurrent generated when the moving and stationary contacts of the main circuit close into heat dissipated by the closing resistor, preventing excessive current from burning out the corresponding contacts in the main circuit. The circuit breaker disclosed in patent document CN106024505B is of this type.

[0003] In the prior art, the static resistor assembly and the moving resistor assembly can adopt the same structure, specifically as follows: Figure 1 As shown, the device includes a contact and a contact rod assembled together by a screw. A disc spring is provided between the contact and the contact rod, and a disc spring is press-fitted between the contact and the contact rod to achieve preload. A shielding cover is press-fitted between the disc spring and the contact, and the shielding cover is placed on the end of the contact rod to achieve electric field shielding. After installation, the disc spring achieves preload between the contact, the shielding cover, and the contact rod. At the same time, the contact and the contact rod are also fastened together by a set screw. Specifically, the set screw passes through the contact and enters the contact rod, and the set screw acts as an anti-rotation element to prevent relative rotation between the contact and the contact rod.

[0004] Although the aforementioned resistor contact structure can prevent rotation between the contact and the contact rod, in actual use, collisions can occur between the stationary and moving resistor contact assemblies, and the impact force is significant. After the contact is impacted, the force is transmitted to the shield and disc spring. Due to the elastic deformation of the disc spring under pressure, the shield vibrates and eventually deforms. This deformation causes the preload between the contact and the contact rod to fail, resulting in contact wobbling. Ultimately, this can lead to set screw failure and breakage, causing the contact to fall off. Furthermore, the shield creates a gap between itself and the contact during vibration, and the vibration further widens this gap. Once a gap exists between the shield and the contact, a discharge phenomenon can occur at that gap, affecting the normal connection of the main circuit. Summary of the Invention

[0005] The purpose of this invention is to provide a closing resistor contact assembly for a circuit breaker, thereby solving the technical problems of contact detachment and gap discharge between the shield and the contact in the prior art resistor contact structure. This invention also provides a circuit breaker to solve the technical problems of contact detachment and gap discharge between the shield and the contact in the prior art resistor contact structure.

[0006] To achieve the above objectives, the technical solution of the closing resistor contact assembly of the circuit breaker provided by the present invention is as follows: A closing resistor contact assembly of a circuit breaker includes a contact rod and a contact. The end of the contact rod is provided with a threaded hole. The contact includes a contact body and an external threaded section that mates with the threaded hole. A pre-tightening member is press-fitted between the contact and the contact rod. A shielding cover is provided on the outside of the contact rod. A groove is provided on the contact rod. The threaded hole is located at the bottom of the groove. A protrusion adapted to the groove is provided on the contact between the contact body and the external threaded section. The pre-tightening member is press-fitted between the bottom of the groove and the protrusion. The shielding cover is fitted over the protrusion and pressed by the contact on the end face of the contact rod.

[0007] The beneficial effects are as follows: The closing resistor contact assembly provided by the present invention has a protrusion between the contact body and the external threaded section of the contact. After the external threaded section of the contact is screwed into the threaded hole on the contact rod, the end face of the protrusion presses the pre-tightening member between the groove and the protrusion of the contact rod, and the shielding cover is fitted onto the protrusion. Unlike the prior art where the pre-tightening member is installed on the shielding cover and the contact rod, the shielding cover and the pre-tightening member are set in different positions. Only the pre-tightening member is pressed at the connection between the contact rod and the contact, which can achieve reliable thread fastening and prevent the contact from falling off. Meanwhile, the shield is pressed between the contact rod and the contact. Both the contact rod and the contact are rigid components, which can prevent the shield from vibrating and deforming due to the elastic deformation of the pre-tightening component. This reduces the gap between the shield and the contact, preventing gap discharge. Furthermore, by directly placing the shield between the contact rod and the contact, and with the contact rod and contact being screw-assembled and pre-tightened by the anti-rotation component, the contact and contact rod can directly act on the shield. The shield is subjected to a large force, making it less prone to vibration and rotation, which is beneficial to the stability of the contact and prevents the contact from falling off.

[0008] As a further improvement, the closing resistor contact assembly also includes an anti-rotation element, which connects the contact and the contact rod to prevent relative rotation between the contact and the contact rod. The shield is provided with an anti-rotation element through-hole, through which the anti-rotation element passes.

[0009] The beneficial effect is that the anti-rotation component penetrating the shield can prevent the shield from rotating, further preventing pre-tightening failure caused by the rotation of the shield, and thus avoiding discharge phenomena.

[0010] As a further improvement, a washer is provided between the shield and the contact rod, the washer being fitted onto the protrusion, and the diameter of the washer being larger than the diameter of the end of the contact rod facing the contact.

[0011] The beneficial effects are: by setting a washer with a diameter larger than that of the contact end between the shield and the contact rod, the contact area between the contact rod and the shield can be increased, the force exerted by the contact rod on the shield can be dispersed, and the shield can be prevented from deforming due to excessive force concentration.

[0012] As a further improvement, the closing resistor contact assembly also includes an anti-rotation element, which connects the contact head and the contact rod to prevent the contact head and the contact rod from rotating relative to each other. The shield and the washer are both provided with anti-rotation element through holes, and the anti-rotation element passes through the anti-rotation element through the through holes.

[0013] The beneficial effects are: the anti-rotation component penetrates the shielding cover, and a washer is set between the shielding cover and the contact. The anti-rotation component and the washer together limit the shielding cover, which can restrict the axial and radial directions of the shielding cover and further prevent the shielding cover from rotating; and the washer can increase the contact area between the shielding cover and the contact rod, which can disperse the force of the contact rod on the shielding cover and help avoid the shielding cover deformation caused by excessive force concentration.

[0014] As a further improvement, the preload includes a flat washer and a spring washer.

[0015] The beneficial effects are: the flat washer and the spring washer together form a preload, which has a simple structure and is easy to install. Moreover, the combination of the flat washer and the spring washer has a greater preload force compared with the disc spring of the existing technology.

[0016] The circuit breaker technical solution provided by this invention is as follows: A circuit breaker includes an arc-extinguishing chamber, in which a main circuit and a resistance circuit are arranged in parallel. The main circuit includes a main circuit stationary contact and a main circuit moving contact. The resistance circuit includes a closing resistor stationary contact assembly, a closing resistor moving contact assembly, and a closing resistor. Both the closing resistor stationary contact assembly and the closing resistor moving contact assembly include a contact rod and a contact. The end of the contact rod is provided with a threaded hole. The contact includes a contact body and an external threaded section that mates with the threaded hole. A pre-tightening member is press-fitted between the contact and the contact rod. A shielding cover is provided on the outside of the contact rod. A groove is provided on the contact rod, and the threaded hole is located at the bottom of the groove. A protrusion adapted to the groove is provided on the contact between the contact body and the external threaded section. The pre-tightening member is press-fitted between the bottom of the groove and the protrusion. The shielding cover is fitted over the protrusion and pressed by the contact on the end face of the contact rod.

[0017] The beneficial effects are as follows: The circuit breaker provided by the present invention has a protrusion between the contact body and the external threaded section of the contact. After the external threaded section of the contact is screwed into the threaded hole on the contact rod, the end face of the protrusion presses the pre-tightening member between the groove and the protrusion of the contact rod, and the shielding cover is fitted onto the protrusion. Unlike the prior art where the pre-tightening member is installed on the shielding cover and the contact rod, the shielding cover and the pre-tightening member are set in different positions. Only the pre-tightening member is pressed at the connection between the contact rod and the contact, which can achieve reliable thread fastening and prevent the contact from falling off. Meanwhile, the shield is pressed between the contact rod and the contact. Both the contact rod and the contact are rigid components, which can prevent the shield from vibrating and deforming due to the elastic deformation of the pre-tightening component. This reduces the gap between the shield and the contact, preventing gap discharge. Furthermore, by directly placing the shield between the contact rod and the contact, and with the contact rod and contact screw-assembled together and pre-tightened by the anti-rotation component, the contact and contact rod can directly act on the shield. The shield is subjected to a large force, making it less prone to vibration and rotation, which is beneficial to the stability of the contact and prevents the contact from falling off. This ensures the normal operation of the circuit breaker's resistance circuit and improves the reliability of the circuit breaker.

[0018] As a further improvement, the closing resistor contact assembly also includes an anti-rotation element, which connects the contact and the contact rod to prevent relative rotation between the contact and the contact rod. The shield is provided with an anti-rotation element through-hole, through which the anti-rotation element passes.

[0019] The beneficial effect is that the anti-rotation component penetrating the shield can prevent the shield from rotating, further preventing pre-tightening failure caused by the rotation of the shield, and thus avoiding discharge phenomena.

[0020] As a further improvement, a washer is provided between the shield and the contact rod, the washer being fitted onto the protrusion, and the diameter of the washer being larger than the diameter of the end of the contact rod facing the contact.

[0021] The beneficial effects are: by setting a washer with a diameter larger than that of the contact end between the shield and the contact rod, the contact area between the contact rod and the shield can be increased, the force exerted by the contact rod on the shield can be dispersed, and the shield can be prevented from deforming due to excessive force concentration.

[0022] As a further improvement, the closing resistor contact assembly also includes an anti-rotation element, which connects the contact head and the contact rod to prevent the contact head and the contact rod from rotating relative to each other. The shield and the washer are both provided with anti-rotation element through holes, and the anti-rotation element passes through the anti-rotation element through the through holes.

[0023] The beneficial effects are: the anti-rotation component penetrates the shielding cover, and a washer is set between the shielding cover and the contact. The anti-rotation component and the washer together limit the shielding cover, which can restrict the axial and radial directions of the shielding cover and further prevent the shielding cover from rotating; and the washer can increase the contact area between the shielding cover and the contact rod, which can disperse the force of the contact rod on the shielding cover and help avoid the shielding cover deformation caused by excessive force concentration.

[0024] As a further improvement, the preload includes a flat washer and a spring washer.

[0025] The beneficial effects are: the flat washer and the spring washer together form a preload, which has a simple structure and is easy to install. Moreover, the combination of the flat washer and the spring washer has a greater preload force compared with the disc spring of the existing technology. Attached Figure Description

[0026] Figure 1 A schematic diagram of the closing contact structure in the prior art;

[0027] Figure 2 A schematic diagram of the structure of the moving resistor contact and the stationary resistor contact in Embodiment 1 of the circuit breaker provided by the present invention;

[0028] Figure 3 for Figure 2 A schematic diagram of the closing resistor contact assembly.

[0029] Explanation of reference numerals in the attached diagram: 1. Arc-extinguishing chamber; 2. Main circuit; 3. Resistor circuit; 4. Stationary contact assembly of closing resistor; 5. Moving contact assembly of closing resistor; 6. Contact rod; 7. Contact; 8. Shielding cover; 9. Disc spring; 10. Anti-rotation component; 11. Contact body; 12. Protrusion; 13. External thread section; 14. Washer; 15. Flat washer; 16. Spring washer; 17. Groove; 18. Threaded hole. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0032] It should be noted that, in specific embodiments of the present invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply such an actual relationship or order between these entities or operations. Furthermore, terms such as "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, the use of phrases such as "comprising a…" to define an element does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0033] In the description of this invention, unless otherwise explicitly specified and limited, terms such as "installation," "connection," and "linkage" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] In the description of this invention, unless otherwise explicitly specified and limited, the term "provided with" should be interpreted broadly. For example, the object "provided with" can be a part of the body, or it can be separately arranged from the body and connected to the body. This connection can be a detachable connection or a non-detachable connection. Those skilled in the art can understand the specific meaning of the above terms in this invention through specific circumstances.

[0035] The present invention will be further described in detail below with reference to the embodiments.

[0036] Embodiment 1 of the circuit breaker provided in this invention:

[0037] like Figure 2As shown, the circuit breaker includes an arc-extinguishing chamber 1, which contains a main circuit 2 and a resistor circuit 3. The resistor circuit 3 is connected in parallel below the main circuit 2. The main circuit 2 includes a main circuit stationary contact and a main circuit moving contact (not shown in the figure). The resistor circuit 3 includes a closing resistor stationary contact assembly 4, a closing resistor moving contact assembly 5, and a closing resistor (not shown in the figure). The closing resistor stationary contact assembly 4 is conductively connected below the main circuit stationary contact, and the closing resistor moving contact assembly 5 is conductively connected below the main circuit moving contact. When the circuit breaker closes, the moving resistor in the closing resistor moving contact assembly 5 gradually approaches the moving resistor in the closing resistor stationary contact assembly 4 along with the main circuit moving contact. The moving resistor and the stationary resistor are connected before the main circuit moving contact is connected to the main circuit stationary contact, so as to convert the instantaneous large current of closing into the heat of the closing resistor and avoid the large current burning out the contacts in the main circuit 2. The connection methods of the main circuit 2 of the circuit breaker and the main circuit 2 and the resistor circuit 3 are existing technologies and will not be described in detail here. The closing resistor stationary contact assembly 4 and the closing resistor moving contact assembly 5 have the same structure. The difference is that a spring is additionally provided at the closing resistor stationary contact assembly 4 to ensure reliable engagement of the two contact assemblies.

[0038] Both the stationary contact assembly 4 and the moving contact assembly 5 of the closing resistor are closing resistor contact assemblies. Taking the stationary contact assembly 4 as an example... Figure 3 As shown, the closing resistor stationary contact assembly 4 includes a contact rod 6, a contact 7, and a shield 8. The shield 8 is a spun part, press-fitted between the contact rod 6 and the contact 7 to shield the electric field at the contact rod 6 and the contact 7. The contact 7 includes a contact body 11, which has an arc-shaped side and a smooth side. The edge of the arc-shaped side connects with the edge of the smooth side. The arc-shaped side is used for electrical connection with the resistor stationary contact assembly 5 in the resistor circuit 3, and the smooth side is used for press-fitting with the contact rod 6. The smooth side has an extension, and the outer circumferential surface of the extension has an external thread to form an external thread section 13. The external thread section 13 is used for connection with the contact rod 6. The outer circumferential surface of the root of the external thread section 13 has an annular protrusion 12, and the shield 8 is fitted onto the protrusion 12.

[0039] One end of the contact rod 6 is provided with a groove 17, which allows the protrusion 12 of the contact 7 to be inserted during connection. The bottom of the groove 17 is provided with a threaded hole 18, which allows the external threaded section 13 of the contact 7 to be screwed into, thereby realizing the connection between the contact 7 and the contact rod 6. The other end of the contact 7 is used for conductive connection with the main circuit 2.

[0040] A flat washer 15 and a spring washer 16 are fitted onto the external threaded section 13 of the contact 7. After the external threaded section 13 of the contact 7 is rotated into the threaded hole 18 of the contact rod 6, the flat washer 15 and the spring washer 16 are positioned between the protrusion 12 of the contact 7 and the groove 17 of the contact rod 6. A washer 14 is fitted onto the protrusion 12 of the contact 7. After the external threaded section 13 of the contact 7 is rotated into the threaded hole 18 of the contact rod 6, the washer 14 is pressed between the shielding cover 8 and the contact rod 6. The flat washer 15 and the spring washer 16 form a pre-tightening element to pre-tighten the contact 7 and the contact rod 6, thereby increasing the connection strength between the contact 7 and the contact rod 6 and preventing loosening between the contact 7 and the contact rod 6. Furthermore, the diameter of the washer 14 is larger than the diameter of the end of the contact rod 6 that contacts the shield 8, so as to increase the contact area between the contact rod 6 and the shield 8, disperse the force of the contact rod 6 on the shield 8, and avoid the phenomenon of deformation of the shield 8 due to excessive force concentration.

[0041] To prevent the contact rod 6, contact 7, and shield 8 from rotating and falling off, two oppositely arranged anti-rotation holes are provided on the contact body 11 around the protrusion 12, and two through holes are provided on the shield 8. Two connecting holes are provided on the washer 14. When the washer 14 and shield 8 are fitted onto the protrusion 12 of the contact 7, the anti-rotation holes, through holes, and connecting holes all serve as through holes for anti-rotation components and are correspondingly connected. By inserting the anti-rotation component 10 through the contact 7, shield 8, and washer 14, the anti-rotation of the shield 8, contact rod 6, and contact 7 is achieved. In this embodiment, the anti-rotation component 10 is a set screw, which is inserted into the contact rod 6 by self-tapping.

[0042] When the circuit breaker is closed, the moving contact assembly 5 of the closing resistor gradually approaches the stationary contact assembly 4 of the closing resistor along with the moving contact of the main circuit. The moving contact of the closing resistor assembly 5 and the stationary contact of the closing resistor assembly 4 are connected before the moving contact and the stationary contact of the main circuit are connected, so as to convert the instantaneous large current of closing into the heat of the closing resistor, thereby avoiding the large current from burning out the contacts in the main circuit 2.

[0043] The circuit breaker provided by this invention has a protrusion 12 between the contact body 11 and the external thread section 13 of the contact 7 in the closing resistor contact assembly. After the external thread section 13 of the contact 7 is screwed into the threaded hole 18 on the contact rod 6, the end face of the protrusion 12 presses the pre-tightening member between the groove 17 and the protrusion 12 of the contact rod 6, and the shield 8 is fitted onto the protrusion 12. Unlike the prior art where the pre-tightening member is installed on the shield 8 and the contact rod 6, the shield 8 and the pre-tightening member are set in different positions. Only the pre-tightening member is pressed at the connection between the contact rod 6 and the contact 7, which can achieve reliable thread fastening and prevent the contact 7 from falling off. Meanwhile, the shield 9 is pressed between the contact rod 6 and the contact 7. Both the contact rod 6 and the contact 7 are rigid components, which can prevent the shield 8 from vibrating and deforming due to the elastic deformation of the pre-tightening component. This reduces the gap between the shield 8 and the contact 7, preventing gap discharge. Furthermore, the shield 8 is directly placed between the contact rod 6 and the contact 7. The contact rod 6 and the contact 7 are screw-assembled and pre-tightened by the anti-rotation component 10, allowing the contact 7 and the contact rod 6 to directly act on the shield 8. The shield 8 is subjected to a large force, making it less prone to vibration and rotation. This is beneficial to the stability of the contact 7, preventing the contact 7 from falling off. This ensures the normal operation of the circuit breaker's resistance circuit 3, thereby improving the reliability of the circuit breaker.

[0044] Embodiment 2 of the circuit breaker provided in this invention:

[0045] The difference between this embodiment and Embodiment 1 is that in Embodiment 1, a washer 14 with a diameter larger than that of the contact rod 6 is provided between the shielding cover 8 and the contact rod 6. In this embodiment, the diameter of the washer 14 is the same as the diameter of the contact rod 6.

[0046] Of course, in other embodiments, the gasket 14 may not be provided between the shielding cover 8 and the contact rod 6, and the contact rod 6 may directly contact the shielding cover 8.

[0047] Embodiment 3 of the circuit breaker provided in this invention:

[0048] The difference between this embodiment and Embodiment 1 is that in Embodiment 1, a flat washer 15 and a spring washer 16 are provided between the protrusion 12 of the contact 7 and the groove 17 of the contact rod 6, forming a pre-tightening element. In this embodiment, the pre-tightening element can be a disc spring or the like.

[0049] Embodiment 4 of the circuit breaker provided in this invention:

[0050] The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the shielding cover 8 is provided with an anti-rotation perforation, through which the anti-rotation member 10 passes. In this embodiment, however, the shielding cover 8 is no longer provided with an anti-rotation perforation, and the end of the anti-rotation member 10 rests against the shielding cover 8.

[0051] The present invention also provides an embodiment of a closing resistor contact assembly for a circuit breaker:

[0052] The closing resistor contact assembly structure of the circuit breaker in this embodiment is the same as that in the circuit breaker embodiment 1 above, and will not be described again here.

[0053] Of course, in other embodiments, the closing resistor contact assembly of the circuit breaker may also use the structure of the closing resistor contact assembly in embodiment 2, 3 or 4 of the circuit breaker, which will not be described in detail here.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be determined by the claims. Similarly, any equivalent structural changes made based on the description and drawings of the present invention shall also be included within the scope of protection of the present invention.

Claims

1. A closing resistor contact assembly for a circuit breaker, comprising a contact rod (6) and a contact (7), wherein the end of the contact rod (6) is provided with a threaded hole (18), the contact (7) includes a contact body (11) and an external threaded section (13) that mates with the threaded hole (18), a preload is press-fitted between the contact (7) and the contact rod (6), and a shielding cover (8) is provided on the outside of the contact rod (6); characterized in that, The contact rod (6) is provided with a groove (17), and the threaded hole (18) is provided at the bottom of the groove (17). The contact (7) is provided with a protrusion (12) that is adapted to the groove (17) between the contact body (11) and the external thread section (13). The pre-tightening member is pressed between the bottom of the groove (17) and the protrusion (12). The shield (8) is fitted on the outside of the protrusion (12) and is pressed by the contact (7) on the end face of the contact rod (6).

2. The closing resistor contact assembly of the circuit breaker according to claim 1, characterized in that, The closing resistor contact assembly also includes an anti-rotation element (10), which connects the contact (7) and the contact rod (6) to prevent the contact (7) and the contact rod (6) from rotating relative to each other. The shield (8) is provided with an anti-rotation element through hole, and the anti-rotation element (10) passes through the anti-rotation element through hole.

3. The closing resistor contact assembly of the circuit breaker according to claim 1, characterized in that, A washer (14) is provided between the shield (8) and the contact rod (6). The washer (14) is fitted onto the protrusion (12). The diameter of the washer (14) is larger than the diameter of the end of the contact rod (6) facing the contact (7).

4. The closing resistor contact assembly of the circuit breaker according to claim 3, characterized in that, The closing resistor contact assembly also includes an anti-rotation element (10), which connects the contact (7) and the contact rod (6) to prevent the contact (7) and the contact rod (6) from rotating relative to each other. The shield (8) and the washer (14) are both provided with anti-rotation through holes, and the anti-rotation element (10) passes through the anti-rotation through holes.

5. The closing resistor contact assembly of the circuit breaker according to any one of claims 1 to 4, characterized in that, The preload includes a flat washer (15) and a spring washer (16).

6. A circuit breaker, comprising an arc-extinguishing chamber (1), wherein the arc-extinguishing chamber (1) is provided with a main circuit (2) and a resistance circuit (3) connected in parallel, the main circuit (2) comprising a main circuit stationary contact and a main circuit moving contact, the resistance circuit (3) comprising a closing resistor stationary contact assembly (4), a closing resistor moving contact assembly (5) and a closing resistor, both the closing resistor stationary contact assembly (4) and the closing resistor moving contact assembly (5) comprising a contact rod (6) and a contact (7), the end of the contact rod (6) being provided with a threaded hole (18), the contact (7) comprising a contact body (11) and an external threaded section (13) cooperating with the threaded hole (18), a pre-tightening member being press-fitted between the contact (7) and the contact rod (6), and a shielding cover (8) being provided on the outside of the contact rod (6); characterized in that, The contact rod (6) is provided with a groove (17), and the threaded hole (18) is provided at the bottom of the groove (17). The contact (7) is provided with a protrusion (12) that is adapted to the groove (17) between the contact body (11) and the external thread section (13). The pre-tightening member is pressed between the bottom of the groove (17) and the protrusion (12). The shield (8) is fitted on the outside of the protrusion (12) and is pressed by the contact (7) on the end face of the contact rod (6).

7. The circuit breaker according to claim 6, characterized in that, The closing resistor contact assembly also includes an anti-rotation element (10), which connects the contact (7) and the contact rod (6) to prevent the contact (7) and the contact rod (6) from rotating relative to each other. The shield (8) is provided with an anti-rotation element through hole, and the anti-rotation element (10) passes through the anti-rotation element through hole.

8. The circuit breaker according to claim 6, characterized in that, A washer (14) is provided between the shield (8) and the contact rod (6). The washer (14) is fitted onto the protrusion (12). The diameter of the washer (14) is larger than the diameter of the end of the contact rod (6) facing the contact (7).

9. The circuit breaker according to claim 8, characterized in that, The closing resistor contact assembly also includes an anti-rotation element (10), which connects the contact (7) and the contact rod (6) to prevent the contact (7) and the contact rod (6) from rotating relative to each other. The shield (8) and the washer (14) are both provided with anti-rotation through holes, and the anti-rotation element (10) passes through the anti-rotation through holes.

10. The circuit breaker according to any one of claims 6 to 9, characterized in that, The preload includes a flat washer (15) and a spring washer (16).

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