Universal large-current double-throw isolating switch

Abstract

The invention discloses a general large-current double-throw disconnecting switch which comprises a machine base component, a conductive component and a driving component. A wire inlet terminal, an output terminal and a middle terminal are arranged on the machine base part, a V-shaped movable knife switch assembly is connected to the middle terminal through a hinge, the V-shaped movable knife switch assembly is composed of four groups of copper bars, and beryllium bronze contacts subjected to special heat treatment are pressed into the copper bars; the four groups of knife switches are compressed by the corresponding number of belleville springs; the hardness of the main shaft of the machine base is HB52-58 after the main shaft is modulated by bearing steel GCr15, needle bearings are arranged at the two ends of the main shaft, friction force is extremely small, and the machine base is resistant to abrasion and saves labor. The switch with the structure is stable and safe in performance and long in service life, and can meet wide requirements of large current on-off, isolation and the like in an alternating current and direct current power transmission and distribution system.

Description

Technical Field

[0001] This invention belongs to the field of power transmission equipment design and manufacturing, and is particularly applicable to high-current double-throw disconnectors for medium voltage (3.6kV) and high current (5.3kA) applications in rail transit traction power supply substations, as well as power supply to maintenance and repair depots for electric locomotives. It is suitable for medium and low voltage, high current power transmission and distribution systems as a key component for the connection, isolation, and conversion of high-voltage power. It has wide applications in medium-voltage three-phase four-wire mains power grids, as well as in the metallurgical, machinery, chemical, automotive, and nuclear energy industries, and in any field involving medium voltage and high current. Background Technology

[0002] To date, in most urban rail transit systems in my country, key electrical components for the traction power supply systems of subways and light rails are still imported products, including double-throw disconnect switches.

[0003] The existing imported disconnect switches, widely used by companies such as SECHRON from Switzerland and Alfa from the Czech Republic, have the following problems:

[0004] 1. The positioning mechanism for the opening and closing of the conductive moving switch is not reasonably designed: it uses a steel cam sleeved on the main shaft to make hard contact with the aluminum base for positioning, which will cause the aluminum base to be damaged or worn prematurely.

[0005] 2. The spindle is made of medium carbon steel without heat treatment to increase its hardness, and it directly fits with the aluminum base to form a sliding friction pair. This will cause significant wear during operation, resulting in a short mechanical life of the switch and requiring a large operating torque.

[0006] 3. The contacts on the moving switch are silver contacts that are pressed in. The input and output copper terminals at both ends usually use thin plate springs, which have weak pressure. The pressure of each silver contact is less than 2kg, which prevents the switch from making full contact with the conductive terminals, reduces the conductor cross-section, increases the contact resistance, and causes the disconnecting switch to heat up during use.

[0007] 4. In the conductive components, the three large conductive terminals carrying high currents are all made using traditional pure copper lost-wax precision casting. This precision casting process is complex, has an extremely long casting cycle, and requires a large amount of machining work. It is costly and time-consuming. Summary of the Invention

[0008] The purpose of this invention is to solve the above-mentioned technical problems of existing high-current dual-throw disconnect switches and to provide a universal switching medium-voltage disconnect switch with good safety, long service life, low friction, or remote operation.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following solution:

[0010] A high-current double-throw disconnect switch includes a base assembly, conductive components, and a drive assembly. The base assembly has a main shaft, a swing connecting rod, and an insulating rod mounted on the base. The swing connecting rod and the insulating rod are located at the middle and right ends of the main shaft, respectively, and are connected to the main shaft.

[0011] The conductive component is located on the base component, and the insulating rod is connected to the connecting swing rod via a small shaft. The drive component is connected to the base component.

[0012] The base component includes a main shaft, a connecting swing arm, an insulating rod, and a small shaft mounted on the base. The connecting swing arm and the insulating rod are located at the middle and right ends of the main shaft, respectively, and are connected to the main shaft. The conductive component is located on the base component, and the insulating rod is connected to the connecting swing arm via a small shaft.

[0013] In the base component, two needle roller bearings are provided on each side of the connection position between the main shaft and the connecting rocker arm; the small shafts are all provided with miniature needle roller bearings without inner rings.

[0014] The main shaft of the base component is made of bearing steel GCr15, and after tempering, it achieves a hardness of HB52-58.

[0015] The main shaft of the machine base uses needle roller bearings at both ends, which results in minimal friction between the gears and mechanical limiters connected at both ends, making it wear-resistant and labor-saving.

[0016] In the above technical solution, the conductive component is provided with three conductive terminal base plates and terminal plates, and the conductive terminals are made by silver hard soldering; the middle terminal of the conductive terminal is hinged to four sets of V-shaped moving switch assemblies, and beryllium bronze conductive contacts are pressed into the moving switches. After the contacts are heat-treated by a special process, the hardness is HRC42-43.

[0017] In the above technical solution, the moving switch and the copper terminal are pressed together by a disc spring, which has a large pressing force and extremely low resistance of the moving contact.

[0018] In the above technical solution, the driving component further includes a main shaft mounted on a base and rotatable along its own axis, and a driving mechanism that drives the main shaft to rotate. One end of the main shaft is connected to a bevel gear set and a motor assembly of the driving component, and the other end is connected to a mechanical limit body that plays a control role. When the DC torque motor receives a main control signal, the bevel gear set drives the contact driving mechanism to operate, thereby closing one side of the V-shaped moving switch assembly with the incoming terminal or closing the other side of the V-shaped moving switch assembly with the output terminal, realizing the isolation or switching function of the double-throw switch.

[0019] Furthermore, the above-mentioned scheme also allows for manual operation of the high-current double-throw disconnect switch via a hand crank. A hand crank mechanism is installed at the tail of the DC torque motor. By inserting the hand crank into the hand crank hole at the tail of the DC torque motor and rotating the hand crank, the high-current double-throw disconnect switch can be manually operated to isolate or switch between different positions, which is simple and safe.

[0020] The aforementioned switch with this structure has stable performance, high safety, and long service life, which is sufficient to meet the extensive needs of traction power supply systems for urban rail transit such as subways, light rails, and intercity railways in my country, as well as three-phase four-wire AC power grids.

[0021] The high-current double-throw disconnect switch, if used to supply power to the maintenance and repair depot of electric locomotives, has two operating conditions: (1) Dual-rail operation: For example, when a subway train needs to enter track A or track B for maintenance, a double-throw switch is used to switch between them, and the two tracks share one double-throw isolating switch.

[0022] In the above applications, (2) it operates on a single track: The intermediate pole is connected to the overhead contact line or electric rail, pole A is connected to the power supply, and pole B is grounded. After the locomotive enters the maintenance track in the workshop, the switch is switched, and the locomotive is directly grounded, eliminating the need for a grounding switch. It can also be used in negative terminal cabinets, and double-throw disconnect switches can replace manual disconnect switches. The beneficial effects of this invention are as follows:

[0023] (1) The contacts of the disconnecting switch's conductive structure are made of alloy copper, with beryllium bronze being the preferred material. After special heat treatment, the hardness of the contacts can reach HRC45±1. Due to the high hardness, wear is minimal or even nonexistent during use, thus improving the service life of the disconnecting switch. Moreover, the beryllium bronze alloy contacts do not generate an electric arc during opening and closing, giving them excellent resistance to arc erosion. At the same time, beryllium bronze itself has excellent electrical conductivity, effectively reducing the contact resistance of the disconnecting switch and meeting relevant standard requirements. (2) The V-shaped moving knife of the conductive structure of the disconnecting switch is pressed with a disc spring to the copper terminal. The pressing force is large, the moving contact resistance is extremely small, and the heat generation is small, which ensures stable switch performance, high safety and long service life. (3) Each of the three conductive terminals consists of two welded parts, namely the terminal block and the conductive tip, which are connected by brazing. Using highly fluid metallic silver as solder to fix the conductive tip to the terminal block can save a lot of copper. Attached Figure Description

[0024] Figure 1 This is a front perspective view of the structure of the present invention;

[0025] Figure 2This is a perspective view of the rear side of the structure of the present invention;

[0026] Figure 3 This is a structural component diagram of the base of the present invention;

[0027] Figure 4 This is a top view of the base component of the present invention;

[0028] Figure 5 This is a structural diagram of the V-shaped moving switch assembly of the conductive component of the present invention;

[0029] Figure 6 This is a structural diagram of a single V-shaped moving switch of the present invention;

[0030] Figure 7 This is a structural diagram of the small shaft assembly of the V-shaped moving gate assembly of the present invention;

[0031] Combination Figures 1 to 7 , In the figure: (1) base component; (2) conductive component; (3) drive component 1. Main shaft; 2. Connecting rocker arm; 3. Insulating rod; 4. V-shaped moving switch; 5. Contact; 6. Incoming terminal; 7. Output terminal; 8. Intermediate terminal; 9. Small shaft; 10. Butterfly spring; 11. Bevel gear set; 12. Mechanical limit body; 13. Rocker arm shaft.

[0032] Figure 8 This is a connection diagram illustrating the operating conditions of the present invention during the dual-track operation of locomotive maintenance;

[0033] Figure 9 This is a connection diagram showing the operating conditions of the present invention in the monorail operation of locomotive maintenance. Detailed Implementation

[0034] The present invention will be specifically described below through embodiments. These embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above-described content of the present invention patent also fall within the scope of protection of the present invention.

[0035] Taking a general-purpose high-current (3.6kV, 5.3kA) double-throw electric disconnector as an example;

[0036] like Figure 1 , Figure 2 As shown, the disconnecting switch in this invention is mainly composed of (1) a base component, (2) a conductive component and (3) a driving component. The components of the disconnecting switch will be described in detail below with reference to the accompanying drawings.

[0037] like Figures 1-7 As shown,

[0038] The base assembly includes a main shaft 1, a connecting rocker arm 2, an insulating rod 3, a small shaft 9, and a rocker arm shaft 13 mounted on the base. Inlet terminals 6, output terminals 7, and intermediate terminals 8 are respectively mounted on the three end insulators. The connecting rocker arm 2 and the insulating rod 3 are located at the middle and right ends of the main shaft, respectively, and are connected to the main shaft 1. The conductive component is located on the base assembly, and the insulating rod 3 is connected to the connecting rocker arm via a small shaft 9. The drive component is connected to the base. When the DC torque motor receives the main control signal, the bevel gear set 11 drives the contact 5 drive mechanism to operate. Through the rocker arm mechanism main shaft 1, the connecting rocker arm 2 and the insulating rod 3 operate, driving four sets of V-shaped moving blades 4. Under the correct limiting action of the mechanical limit body 12, they switch between three working positions: upper closed, middle open, and lower closed, meeting the operating requirements of double-throw disconnect switch switching.

[0039] The entire machine base is equipped with rolling friction and miniaturized bearings. The specific method is as follows: four ball bearings are provided at both ends of the main shaft 1, which are connected to the machine base through spacers; a needle roller bearing without an inner ring is provided on the small shaft 9 on the connecting rocker arm 2, which is connected to the two insulating rods 3 on the left and right sides made of epoxy resin and glass pressure plate, which are wear-resistant.

[0040] The rotating connections between the main shaft 1 and the end cover of the base component, and between the rocker arm shaft 13 and the connecting rocker arm 2, all employ needle roller bearings without inner rings. Both the main shaft 1 and the rocker arm shaft 13 undergo heat treatment to achieve a hardness of HRC62±1, serving as the inner rings of the needle roller bearings. Compared to traditional sliding dry friction pairs, the friction between rotating components can be reduced from a sliding dry friction coefficient of 0.16 to a rolling friction coefficient of 0.003, reducing the operating force of the entire disconnector switch transmission component by more than forty times and extending the service life of the disconnector switch by more than five times.

[0041] The innovative implementation of this switch in the conductive component (2) is as follows:

[0042] like Figures 1-7 As shown, three insulators are installed on the aforementioned aluminum base, and copper conductive terminals for conductive components are respectively installed on the insulators: an input terminal, an output terminal, and an intermediate terminal. The conductive terminals are all made of T1 copper plate material. By using an oxy-acetylene generator to heat the material, the silver brazing electrode is melted and brazed at 750°C, thus creating an innovative high-current conductive terminal.

[0043] The conductive terminal block is equipped with a V-shaped moving switch 4, on which a beryllium bronze contact 5 is pressed. The contact undergoes a special heat treatment process to achieve a hardness of HRC42-43. During use, the contact experiences only minor wear, or even no wear at all, resulting in a contact resistance of 8–9 μΩ between the moving switch assembly and the conductive terminals in the disconnecting switch, meeting the requirements of the electrical performance standards for disconnecting switches (international standards require less than 20 μΩ). In the conductive components, the moving switch and the copper terminals are pressed together by a disc spring 10, providing a large clamping force and extremely low resistance of the moving contact.

[0044] The design and technical requirements of the disconnecting switch structure of this invention comply with the international standards of the International Electrotechnical Commission (IEC61992-1 / 3) and (IEC60129), as well as the design standards and specifications for disconnecting switch products in (EN 50123-1 / 3), and have passed various type tests; it has been partially applied in the power supply systems of rail transit in Beijing, Shanghai, Guangzhou, Chongqing, Chengdu and other cities.

Claims

1. A general-purpose high-current double-throw disconnect switch, comprising a base assembly, conductive components, and a drive assembly. The base assembly houses a main shaft, one end of which is connected to a bevel gear set and combined with a motor of the drive assembly; the other end is connected to a mechanical limit body for control. A rocker arm and an insulating rod are connected in the middle of the main shaft, and insulators are mounted on three end faces of the base assembly. The conductive components include an input terminal, an output terminal, and an intermediate terminal.

2. The universal high-current double-throw disconnector according to claim 1, characterized in that: The V-shaped moving switch assembly is hinged to the middle terminal.

3. A general-purpose high-current double-throw disconnector according to claims 1 and 2, characterized in that: The V-type moving switch assembly consists of four sets of copper busbars, each with specially heat-treated beryllium bronze contacts pressed into it. The four sets of switches are held together by a corresponding number of disc springs, resulting in minimal moving contact resistance and extremely low heat generation.

4. A general-purpose high-current double-throw disconnector according to claim 1, characterized in that: The main shaft of the machine base is made of bearing steel GCr15, and after tempering, the hardness reaches HB52~58.

5. A general-purpose high-current dual-throw disconnector according to claims 1 and 4, characterized in that: The main shaft of the machine base uses needle roller bearings at both ends. As a result, the friction between the gears and mechanical limiters connected at both ends is minimal, making it wear-resistant and labor-saving.

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