Low-resistance circuit breaker used in low-temperature environment

Abstract

The invention discloses a low-resistance circuit breaker for a low-temperature environment, and relates to the field of superconducting magnets, and the main points of the technical scheme are that the low-resistance circuit breaker comprises a power mechanism which is used for providing a normally-closed down force and a rapid-disconnection separating force for a circuit breaking contact; the circuit breaking contact is used for keeping normally closed under the action of downward pressure when the superconducting magnet operates normally, and is quickly disconnected under the action of separating force when the superconducting magnet is abnormal; the box body is used for providing an independent vacuum environment for the circuit break contact and is connected with an external conductor and a liquid nitrogen pipeline; and the cooling conductor is used for providing a superconducting path and continuously cooling the superconducting path. The low-temperature and low-resistance circuit breaker is adopted according to the energy release requirement of the high-temperature superconducting magnet, the problem of continuous large heat leakage load from a normal-temperature end to a low-temperature end caused by using a normal-temperature circuit breaker is solved, the refrigeration power of daily operation of the magnet is greatly reduced, and the operation economical efficiency of the magnet is improved.

Description

Technical Field

[0001] The present invention relates to the field of superconducting magnets, and more particularly to a low-blocking circuit breaker used in a cryogenic environment. Background Art

[0002] REBCO high-temperature superconducting tape has the characteristic of no DC resistance at low temperatures, and its current density is more than 2 orders of magnitude higher than that of copper, making it an excellent material for manufacturing strong-field magnets. Using REBCO materials to manufacture magnets can greatly improve the steady-state magnetic field strength, reduce the size of the equipment, reduce the power and cost of the equipment, and achieve environmental protection, energy saving, low carbon and high efficiency.

[0003] Due to the high energy storage density of high-temperature superconducting magnets, when the magnet is in an abnormal state, it needs to quickly release energy. In order to switch the current circuit from the power supply to the energy release resistor, a fast circuit breaker is required; when the magnet excitation power supply adopts a superconducting power supply, the entire current circuit operates at low temperature, so the circuit breaker needs to operate at low temperature and require extremely small resistance, otherwise it will increase the energy consumption of the low-temperature system; the probability of abnormal conditions in superconducting magnets is low, and the circuit breaker does not need to be frequently activated and should be in a long-term closed state; when the superconducting magnet has an abnormal quench, it is necessary to disconnect the magnet from the excitation power supply to connect an external energy release resistor to achieve rapid energy release of the magnet, so as to avoid the magnet energy storage being mainly released to the magnet body and burning. In the quench energy release circuit with a low-resistance energy release resistor, when the circuit breaker between the magnet and the excitation power supply is disconnected, the electrode voltage is only tens of volts at most, but when the resistor is switched to a high-resistance resistor in the following tens of milliseconds, the voltage will rapidly increase to kilovolts to tens of kilovolts. Obviously, conventional switches or circuit breakers cannot meet the requirements of normal operation at temperatures below 77K, withstand voltages above 10kV, and 10 -7 A resistor below Ω is required.

[0004] Therefore, how to study and design a low-blocking circuit breaker for low-temperature environment that can overcome the above-mentioned defects is a problem that we urgently need to solve. Summary of the invention

[0005] In order to solve the deficiencies in the prior art, the purpose of the present invention is to provide a low-blocking circuit breaker for use in low-temperature environments. Aiming at the energy dissipation requirements of high-temperature superconducting magnets, a low-temperature low-blocking circuit breaker is used to avoid the problem of continuous large heat leakage load from the normal temperature end to the low temperature end caused by the use of normal temperature circuit breakers, greatly reduce the refrigeration power of the daily operation of the magnet, and improve the economy of the magnet operation.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions: A low-blocking circuit breaker for low-temperature environments, comprising:

[0007] A power mechanism, used to provide the circuit breaker contacts with downward pressure when normally closed and separation force when quickly disconnected;

[0008] The circuit breaker contacts are used to remain normally closed under the action of downward pressure when the superconducting magnet is operating normally, and to quickly open under the action of separation force when the superconducting magnet is abnormal;

[0009] The box body is used to provide an independent vacuum environment for the breaking contact and is connected to the external conductor and the liquid nitrogen pipeline;

[0010] The cooling conductor is used to provide a superconducting path and continuously cool the superconducting path.

[0011] Furthermore, the downward force provided by the power mechanism is the elastic pressure of the elastic member, and the separation force is the resultant force of the elastic pressure of the elastic member and the thrust generated by the induced reverse current.

[0012] Furthermore, the power mechanism includes a power rod, a spring, an induction copper plate, a copper coil, a bayonet, a lower partition, a middle partition, an upper partition and a support rod;

[0013] The power rod is movably connected with the lower partition, the middle partition and the upper partition, and one end is connected with the bayonet pin, and the other end is fixedly connected with the circuit breaker contact;

[0014] The induction copper plate is fixedly connected to the power rod;

[0015] One end of the spring is fixedly connected to the middle partition plate, and the other end is fixedly connected to the induction copper plate;

[0016] One end of the copper coil is fixedly connected to the lower partition plate, and the other end is fixedly connected to the induction copper plate;

[0017] The two ends of the support rod are fixedly connected to the middle partition plate and the upper partition plate respectively.

[0018] Furthermore, the induction copper plate and the copper coil are made of a high-strength, high-conductivity copper alloy;

[0019] The induction copper plate and the power rod are welded into a whole by Ag50CuZnCdNi;

[0020] And / or, the power rod, the bayonet, the three partitions and the support rod are all made of 304 or 316LN stainless steel.

[0021] Furthermore, the disconnecting contact comprises an upper contact and a lower contact, and a high-purity indium sheet is arranged between the upper contact and the lower contact.

[0022] Furthermore, the upper contact and the lower contact are both composed of a U-shaped copper plate, a first high-temperature superconducting stack, a first cooling tube, a copper cover plate, a stainless steel cover plate and a glass fiber epoxy plate;

[0023] The U-shaped copper plate, the first high-temperature superconducting stack, the copper cover plate, the stainless steel cover plate and the glass fiber epoxy plate are arranged in sequence along the diverging direction of the upper contact and the lower contact, and the first cooling pipe is arranged around the side of the copper cover plate.

[0024] Furthermore, the glass fiber epoxy plate is connected to the stainless steel cover plate by bolts;

[0025] The stainless steel cover plate and the copper cover plate are welded into an integral cover plate by using a silver-based high-temperature solder;

[0026] The first high-temperature superconducting stack, the first cooling tube and the integral cover plate are welded on the U-shaped copper plate by means of a low-temperature solder whose welding temperature does not exceed 220°C.

[0027] Further, the cooling conductor is composed of a second high temperature superconducting stack and a second cooling tube;

[0028] The second high-temperature superconducting stack provides a superconducting path, and the second cooling tube continuously cools the superconducting path.

[0029] Furthermore, the cooling conductor is a multi-layer S-shaped conductor, which provides upward movement space for the circuit breaker contact when it is disconnected.

[0030] Further, the box body includes a vacuum box, a first contact insulating sealing plate, a second contact insulating sealing plate, a first contact joint and a second contact joint;

[0031] The first contact joint realizes that one end of the cooling conductor is connected to the external conductor and the liquid nitrogen pipeline, and the second contact joint realizes that one end of the disconnecting contact is connected to the external conductor and the liquid nitrogen pipeline;

[0032] The first contact insulating sealing plate performs insulating sealing on the connection between the first contact joint and the vacuum box, and the second contact insulating sealing plate performs insulating sealing on the connection between the second contact joint and the vacuum box.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The present invention provides a low-blocking circuit breaker for low-temperature environments. Aiming at the energy dissipation requirements of high-temperature superconducting magnets, a low-temperature low-blocking circuit breaker is used to avoid the problem of continuous large heat leakage load from the normal temperature end to the low temperature end caused by the use of a normal temperature circuit breaker, greatly reducing the refrigeration power of the daily operation of the magnet and improving the economic efficiency of the magnet operation;

[0035] 2. The present invention uses high-temperature superconducting materials as the current input and output leads of the vacuum circuit breaker, which greatly reduces the resistance of the circuit breaker and reduces the heat generation;

[0036] 3. The circuit breaker contact plate of the present invention adopts a composite structure of high-temperature superconducting stack, oxygen-free copper and indium sheet, which greatly reduces the contact resistance between the circuit breaker contact plates;

[0037] 4. The circuit breaker of the present invention replaces the indium sheet layer every time it is opened and closed to ensure a small resistance of the joint. The separate vacuum box design makes the replacement of the indium sheet simple and quick;

[0038] 5. The circuit breaker in the present invention adopts an electromagnetic pulse coil as the disconnection power, which can apply a pulsed disconnection force, shorten the disconnection response time, and accelerate the action speed of the magnetic quench protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0040] Figure 1 is a schematic diagram of the overall structure of an embodiment of the present invention;

[0041] Figure 2 It is a schematic diagram of the internal structure of the circuit breaker contact and the power mechanism in an embodiment of the present invention;

[0042] Figure 3 Schematic diagram of the connection structure of the cooling conductor in the embodiment of the present invention.

[0043] Marks and corresponding parts names in the attached drawings:

[0044] 1. Circuit breaker contact; 1-1. U-shaped copper plate; 1-2. First high-temperature superconducting stack; 1-3. First cooling tube; 1-4. Copper cover plate; 1-5. Stainless steel cover plate; 1-6. Glass fiber epoxy board;

[0045] 2. Box body; 2-1. Vacuum box; 2-2. First contact insulating sealing plate; 2-3. Second contact insulating sealing plate; 2-4. First contact joint; 2-5. Second contact joint;

[0046] 3. Power mechanism; 3-1. Power rod; 3-2. Spring; 3-3. Induction copper plate; 3-4. Copper coil; 3-5. Bayonet; 3-6. Lower partition; 3-7. Middle partition; 3-8. Upper partition; 3-9. Support rod;

[0047] 4. Cooling conductor; 4-1. Second high-temperature superconducting stack; 4-2. Second cooling tube. DETAILED DESCRIPTION

[0048] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0049] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it can be directly on the other component or indirectly on the other component. When a component is referred to as being "connected to" another component, it can be directly or indirectly connected to the other component.

[0050] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0051] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0052] Embodiment: A low-blocking circuit breaker for use in a low-temperature environment, such as Figure 1 As shown, it includes a power mechanism 3, a circuit breaker contact 1, a box body 2 and a cooling conductor 4, and the power mechanism 3, the circuit breaker contact 1 and the cooling conductor 4 are all installed in the box body 2. The moving end of the power mechanism 3 is connected to the circuit breaker contact 1, which is used to provide the circuit breaker contact 1 with a downward pressure when normally closed and a separation force when quickly disconnected; the circuit breaker contact 1 is placed in the superconducting path, which is used to remain normally closed under the action of downward pressure when the superconducting magnet is operating normally, and to quickly disconnect under the action of the separation force when the superconducting magnet is abnormal, thereby realizing the control of the on and off state of the superconducting path; the box body 2 is used to provide an independent vacuum environment for the circuit breaker contact 1, and is connected to the external conductor and the liquid nitrogen pipeline; the cooling conductor 4 is connected to the circuit breaker contact 1 at one end, and the other end is installed on the box body 2 to realize the connection with the external device; the cooling conductor 4 provides a superconducting path and continuously cools the superconducting path.

[0053] The downward force provided by the power mechanism 3 may be the elastic pressure of the elastic member, and the separation force may be the combined force of the elastic pressure of the elastic member and the thrust generated by the induced reverse current.

[0054] As an optional implementation, Figure 1 and Figure 2As shown, the power mechanism 3 includes a power rod 3-1, a spring 3-2, an induction copper plate 3-3, a copper coil 3-4, a bayonet 3-5, a lower partition 3-6, a middle partition 3-7, an upper partition 3-8 and a support rod 3-9. The power rod 3-1 is movably connected with the lower partition 3-6, the middle partition 3-7 and the upper partition 3-8, and one end is connected with the bayonet 3-5, and the other end is fixedly connected with the circuit breaker contact 1; the induction copper plate 3-3 is fixedly connected with the power rod 3-1; one end of the spring 3-2 is fixedly connected with the middle partition 3-7, and the other end is fixedly connected with the induction copper plate 3-3; one end of the copper coil 3-4 is fixedly connected with the lower partition 3-6, and the other end is fixedly connected with the induction copper plate 3-3; the two ends of the support rod 3-9 are fixedly connected with the middle partition 3-7 and the upper partition 3-8 respectively.

[0055] The induction copper plate 3-3 and the copper coil 3-4 are made of high-strength and high-conductivity copper alloys, such as Luozirconium copper, etc. The induction copper plate 3-3 and the power rod 3-1 are welded as a whole by Ag50CuZnCdNi. The power rod 3-1, the bayonet 3-5, the three partitions and the support rod 3-9 are all made of 304 or 316LN stainless steel. In this embodiment, the diameter of the induction copper plate 3-3 and the copper coil 3-4 is 90 mm, the thickness of the copper plate is 15 mm, and the thickness of the copper coil 3-4 is 20 mm.

[0056] like Figure 1 and Figure 2 As shown, the circuit breaker contact 1 includes an upper contact and a lower contact, and a high-purity indium sheet is arranged between the upper contact and the lower contact. The upper contact and the lower contact are both composed of a U-shaped copper plate 1-1, a first high-temperature superconducting stack 1-2, a first cooling tube 1-3, a copper cover plate 1-4, a stainless steel cover plate 1-5 and a glass fiber epoxy plate 1-6; the U-shaped copper plate 1-1, the first high-temperature superconducting stack 1-2, the copper cover plate 1-4, the stainless steel cover plate 1-5 and the glass fiber epoxy plate 1-6 are arranged in sequence along the direction away from the upper contact and the lower contact, and the first cooling tube 1-3 is arranged around the side of the copper cover plate 1-4.

[0057] The glass fiber epoxy plate 1-6 is connected to the stainless steel cover plate 1-5 by bolts; the stainless steel cover plate 1-5 and the copper cover plate 1-4 are welded into an integral cover plate by silver-based high-temperature solder; the first high-temperature superconducting stack 1-2, the first cooling tube 1-3 and the integral cover plate are welded to the U-shaped copper plate 1-1 by low-temperature solder with a welding temperature not exceeding 220°C.

[0058] In this embodiment, the U-shaped copper plate 1-1, the first cooling tube 1-3 and the copper cover plate 1-4 are all oxygen-free copper; the first high-temperature superconducting stack 1-2 is a REBCO or Bi-based high-temperature superconducting tape; the stainless steel cover plate 1-5 is 316 series; the glass fiber epoxy plate 1-6 is G10; and the thickness of the indium sheet is 0.1 to 0.3 mm.

[0059] For example, the width of the U-shaped copper plate 1-1 is 80 mm; the width of the first high-temperature superconducting stack 1-2 is 60 mm; the stainless steel cover plate 1-5 is 316LN; the side length of the first cooling tube 1-3 is 6 mm and the inner diameter is 4 mm; the thickness of the indium sheet is 0.2 mm. The length of the contact superconducting stack overlap area is 50 mm.

[0060] The yield strength of the U-shaped copper plate 1-1 is higher than 150MPa, for example, the yield strength of the U-shaped copper plate 1-1 is 180MPa, and the surface roughness of the overlap surface is Ra3.2~6.3um. The first high-temperature superconducting stack 1-2 and the second high-temperature superconducting stack 4-1 are used to provide a superconducting path to minimize the resistance area of ​​the joint, that is, the resistance area only has non-superconducting materials between the upper contact and the lower contact, and the resistivity of oxygen-free copper and high-purity indium sheets is extremely low at 77K and below. At the same time, reasonable surface roughness can reduce the interface resistance between copper and indium, ensuring that the resistance of the circuit breaker contact 1 is extremely low, that is, the resistance between the first high-temperature superconducting stack 1-2 and the second high-temperature superconducting stack 4-1 is kept below 16nΩ.

[0061] When the first cooling tube 1-3 is cooled by liquid nitrogen, the excellent thermal conductivity of the induction copper plate 3-3 can also make the contact dissipate heat better and maintain the overall low temperature. At the same time, the higher yield strength can also increase the greater mechanical stress during closing and disconnection. The stainless steel cover plate 1-5 can further improve the rigidity of the contact, so that the upper and lower contacts are always parallel and apply uniform downward pressure to the high-purity indium sheet, transmitting the pressure and tension of the power mechanism 3. The glass fiber epoxy board 1-6 provides sufficient insulation to completely insulate the electrical circuit from the power mechanism 3 and the box body 2.

[0062] Under normal working conditions, the spring 3-2 is pressed down to make the upper and lower contacts fit together, and the spacing between the induction copper plate 3-3 and the copper coil 3-4 is 0.3 to 1 mm; when starting to disconnect, a large pulse current is passed through the copper coil 3-4, and the induction copper plate 3-3 induces a reverse current and generates an upward thrust, quickly pushing the upper contact away from the lower contact, and the latch 3-5 passes through the upper partition 3-8. Due to the decrease in current and the increase in spacing, the electromagnetic thrust is less than the thrust of the spring 3-2, and the power rod 3-1 moves downward again and stops at the position of the latch 3-5. The above action is completed within 10ms. During this time, the high-temperature superconducting magnet does not start to dissipate energy, and the voltage between the circuit-breaking contacts 1 is less than tens of volts. Since the indium sheet deforms too much after each downward pressure, and local discharge and melting will occur during disconnection, the pole surface needs to be cleaned again and the indium sheet needs to be replaced after each disconnection.

[0063] For example, under normal working conditions, the distance between the induction copper plate 3-3 and the copper coil 3-4 is 0.5mm, and the average contact pressure is greater than 3MPa; when the power rod 3-1 moves downward again and stops at the position of the latch 3-5, the pole distance between the upper contact and the lower contact is 15mm.

[0064] like Figure 3As shown, the cooling conductor 4 is composed of a second high temperature superconducting stack 4-1 and a second cooling tube 4-2; wherein the second high temperature superconducting stack 4-1 provides a superconducting path, and the second cooling tube 4-2 continuously cools the superconducting path.

[0065] In this embodiment, the cooling conductor 4 is a multi-layer S-shaped conductor, which provides upward movement space for the circuit breaker contact 1 when it is disconnected, and does not produce irreversible strain. The second cooling tube 4-2 continuously cools the second high-temperature superconducting stack 4-1 to take away contact heating, radiation and conduction leakage heat.

[0066] For example, the width of the multi-layer second high temperature superconducting stack 4-1 is 60 mm, the thickness is 1 mm, the bending radius of the S-shaped conductor is 40 mm, the length of the straight section is 100 mm, and there are 4 groups of bends in total.

[0067] It should be noted that the second cooling tube 4-2 is connected to the first cooling tube 1-3, and the two can be designed as an integrated whole, or connected by joints, welding, etc., without limitation. The second high-temperature superconducting stack 4-1 is connected to the first cooling tube 1-3, and the two can be designed as an integrated whole, or connected by joints, welding, etc., without limitation.

[0068] The box body 2 includes a vacuum box 2-1, a first contact insulating sealing plate 2-2, a second contact insulating sealing plate 2-3, a first contact joint 2-4 and a second contact joint 2-5.

[0069] The first contact joint 2-4 is connected to one end of the cooling conductor 4, and the other end of the cooling conductor 4 is connected to the upper contact, so that one end of the cooling conductor 4 can be connected to the external conductor and the liquid nitrogen pipeline, and the first contact insulating sealing plate 2-2 insulates and seals the connection between the first contact joint 2-4 and the vacuum box 2-1.

[0070] The second contact joint 2-5 is connected to the lower contact in the circuit breaker contact 1, so that one end of the circuit breaker contact 1 can be connected to the external conductor and the liquid nitrogen pipeline, and the second contact insulating sealing plate 2-3 insulates and seals the connection between the second contact joint 2-5 and the vacuum box 2-1.

[0071] The first contact insulating sealing plate 2-2 and the second contact insulating sealing plate 2-3 are made of G10, and the joints are made of oxygen-free copper. The vacuum box 2-1 provides an independent vacuum space for the circuit breaker, which is convenient for replacing the indium sheet. Since the space and the mass of the cold body are small, the vacuum can be re-evacuated and the temperature can be lowered in a short time. The insulating sealing plate is used to lead the circuit breaker out of the vacuum box 2-1, and the joint is used for the circuit breaker to connect the superconducting magnet circuit and the cooling circuit.

[0072] The test results of REBCO mechanical crimping joints show that the resistivity can be stably less than 480nΩ·cm at a pressure of 3MPa. 2The contact resistance 1 of the above circuit breaker is less than 16nΩ, and the thermal power is only 1.6W at 77K when 10kA. Liquid nitrogen cooling can fully ensure that the contact maintains low temperature operation.

[0073] Working principle: The present invention is to control the electrode spacing in a vacuum, and the initial voltage of the magnet is low, there is no obvious arc, and the main consideration is the withstand voltage value after disconnection. Therefore, the key is to select structural materials and electrode driving schemes suitable for low temperatures, especially to reduce heat leakage, the driving components also need to operate at low temperatures; and reducing the resistance of the vacuum circuit breaker depends on the use of superconducting materials in the circuit breaker and increasing the contact area.

[0074] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A low-blocking circuit breaker for low-temperature environments, characterized in that: include: A power mechanism (3) is used to provide the circuit breaker contact (1) with a downward pressure when normally closed and a separation force when quickly disconnected; A circuit breaker contact (1) is used to remain normally closed under the action of downward pressure when the superconducting magnet is operating normally, and to quickly open under the action of a separation force when the superconducting magnet is abnormal; The box body (2) is used to provide an independent vacuum environment for the circuit breaker contact (1) and is connected to an external conductor and a liquid nitrogen pipeline; The cooling conductor (4) is used to provide a superconducting path and continuously cool the superconducting path.

2. A low-blocking circuit breaker for low-temperature environment according to claim 1, characterized in that: The downward pressure provided by the power mechanism (3) is the elastic pressure of the elastic member, and the separation force is the resultant force of the elastic pressure of the elastic member and the thrust generated by the induced reverse current.

3. The low-blocking circuit breaker for low-temperature environment according to claim 1, characterized in that: The power mechanism (3) comprises a power rod (3-1), a spring (3-2), an induction copper plate (3-3), a copper coil (3-4), a latch (3-5), a lower partition (3-6), a middle partition (3-7), an upper partition (3-8) and a support rod (3-9); The power rod (3-1) is movably connected with the lower partition (3-6), the middle partition (3-7), and the upper partition (3-8), and one end of the power rod is connected with the bayonet (3-5), and the other end is fixedly connected with the circuit breaker contact (1); The induction copper plate (3-3) is fixedly connected to the power rod (3-1); One end of the spring (3-2) is fixedly connected to the middle partition (3-7), and the other end is fixedly connected to the induction copper plate (3-3); One end of the copper coil (3-4) is fixedly connected to the lower partition (3-6), and the other end is fixedly connected to the induction copper plate (3-3); The two ends of the support rod (3-9) are respectively fixedly connected to the middle partition plate (3-7) and the upper partition plate (3-8).

4. A low-blocking circuit breaker for low-temperature environment according to claim 3, characterized in that: The induction copper plate (3-3) and the copper coil (3-4) are made of a copper alloy with high strength and high conductivity; The induction copper plate (3-3) and the power rod (3-1) are welded into a whole through Ag50CuZnCdNi; And / or, the power rod (3-1), the bayonet (3-5), the three partitions and the support rod (3-9) are all made of 304 or 316LN stainless steel.

5. The low-blocking circuit breaker for low-temperature environment according to claim 1, characterized in that: The disconnecting contact (1) comprises an upper contact and a lower contact, and a high-purity indium sheet is arranged between the upper contact and the lower contact.

6. A low-blocking circuit breaker for low-temperature environment according to claim 5, characterized in that: The upper contact and the lower contact are both composed of a U-shaped copper plate (1-1), a first high-temperature superconducting stack (1-2), a first cooling tube (1-3), a copper cover plate (1-4), a stainless steel cover plate (1-5) and a glass fiber epoxy plate (1-6); The U-shaped copper plate (1-1), the first high-temperature superconducting stack (1-2), the copper cover plate (1-4), the stainless steel cover plate (1-5) and the glass fiber epoxy plate (1-6) are arranged in sequence along the direction away from the upper contact and the lower contact, and the first cooling pipe (1-3) is arranged around the side of the copper cover plate (1-4).

7. A low-blocking circuit breaker for low-temperature environment according to claim 6, characterized in that: The glass fiber epoxy plate (1-6) and the stainless steel cover plate (1-5) are connected by bolts; The stainless steel cover plate (1-5) and the copper cover plate (1-4) are welded to form an integral cover plate by using a silver-based high-temperature solder; The first high-temperature superconducting stack (1-2), the first cooling tube (1-3) and the integral cover plate are welded on the U-shaped copper plate (1-1) by means of a low-temperature solder having a welding temperature not exceeding 220°C.

8. The low-blocking circuit breaker for low-temperature environment according to claim 1, characterized in that: The cooling conductor (4) is composed of a second high-temperature superconducting stack (4-1) and a second cooling tube (4-2); The second high-temperature superconducting stack (4-1) provides a superconducting path, and the second cooling tube (4-2) continuously cools the superconducting path.

9. The low-blocking circuit breaker for low-temperature environment according to claim 1, characterized in that: The cooling conductor (4) is a multi-layer S-shaped conductor, which provides upward movement space for the disconnecting contact (1) when it is disconnected.

10. The low-blocking circuit breaker for low-temperature environment according to claim 1, characterized in that: The box body (2) comprises a vacuum box (2-1), a first contact insulating sealing plate (2-2), a second contact insulating sealing plate (2-3), a first contact joint (2-4) and a second contact joint (2-5); The first contact joint (2-4) enables one end of the cooling conductor (4) to be connected to the external conductor and the liquid nitrogen pipeline, and the second contact joint (2-5) enables one end of the disconnecting contact (1) to be connected to the external conductor and the liquid nitrogen pipeline; The first contact insulating sealing plate (2-2) performs insulating sealing on the connection between the first contact joint (2-4) and the vacuum box (2-1), and the second contact insulating sealing plate (2-3) performs insulating sealing on the connection between the second contact joint (2-5) and the vacuum box (2-1).

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