Switching device with terminal contacts
By using sandwich structure and slot motor to enhance the magnetic field in the contacts of the switching device, the problem of excessive arc duration is solved, and a safer and more efficient current interruption is achieved.
Patent Information
- Application Number
- CN202380077414.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-01-05
- Filing Date
- 2023-11-20
- Publication Date
- 2025-06-17
AI Technical Summary
The existing switching devices switch from the on-state to the non-conductive state or in a short-circuit case have a longer duration of arcs, resulting in an increased risk of contact melting and it is difficult to safely interrupt the load current flowing through the device.
The first and second terminal contacts of a sandwich structure are adopted, wherein the first layer is made of non-ferromagnetic material, the second layer is made of ferromagnetic material, and the first and second movable contacts are provided at the contact bridge, and the enhanced magnetic field is provided with the slot motor to reduce the arcing time of the arc.
By reducing the arc time of the arc, the risk of contact melting is reduced, and the circuit breaking performance of the switching device in the case of short circuit is improved, significantly reducing the total arc time.
Smart Images
Figure CN120167076A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to a switching device having a first terminal contact and a second terminal contact. Background Art
[0002] The switching device is implemented as an electromechanical switching device. The switching device is configured to conduct and switch, for example, bidirectional AC current or DC current. The switching device is implemented as a circuit breaker, for example. In the case where the switching device is set from a conducting state to a non-conducting state, an arc is generated. Similarly, in the case of a short circuit, the electrodynamic lift-off of the contacts also results in an arc. The arc has a duration called the arcing time. In order to reduce contact melting and safely interrupt the load current flowing through the switching device, the arcing time should be kept short. Summary of the Invention
[0003] The object is to provide a switching device that reduces the arcing time.
[0004] This object is achieved by the subject matter of the independent claims. Further developments and embodiments are described in the dependent claims.
[0005] There is provided a switching device including a first terminal contact and a second terminal contact, a first fixed contact arranged at the first terminal contact, a second fixed contact arranged at the second terminal contact, a contact bridge, and a first movable contact and a second movable contact arranged at the contact bridge.
[0006] In an embodiment of the switching device, the first terminal contact and the second terminal contact include a sandwich structure of at least a first layer and a second layer. The first layer is made of a non-ferromagnetic material, and the second layer is made of a ferromagnetic material.
[0007] Advantageously, the second layer with the ferromagnetic material enhances the magnetic field that drives the first arc away from the first fixed contact and the first movable contact and also drives the second arc away from the second fixed contact and the second movable contact. By the enhanced magnetic field, the arcing time is reduced. The arcing time refers to the time between the generation and the extinction of the arc.
[0008] In an embodiment, the switching device includes a slot motor, which includes a first motor part and a second motor part.
[0009] In a further development of the switching device, a first motor part and a second motor part provide magnetic fields at a first fixed contact and a second fixed contact, and at a first movable contact and a second movable contact. In an example, the first motor part is configured to provide a magnetic field at the first fixed contact and at the first movable contact in a case where the first movable contact is in contact with the first fixed contact and in a case where the first movable contact is at a maximum distance from the first fixed contact. The second motor part is configured to provide a magnetic field at the second fixed contact and at the second movable contact in a case where the second movable contact is in contact with the second fixed contact and in a case where the second movable contact is at a maximum distance from the second fixed contact. The maximum distance is caused, for example, by a short - circuit condition and / or by setting the switching device from an on - state of the switching device to an off - state of the switching device.
[0010] Advantageously, the slot motor enhances the magnetic fields that drive the arc away from the first fixed contact and the second fixed contact, and the first movable contact and the second movable contact. Thereby, the risk of contact melting is reduced and the arcing time is decreased.
[0011] In an embodiment of the switching device, the non - ferromagnetic material is copper or an alloy of copper, such as Cu - PHC or CuAl5. Cu - PH is the abbreviation of phosphorus - deoxidized high - conductivity copper; Cu - PHC is extremely pure copper deoxidized by adding phosphorus. CuAl5 is a copper - aluminum alloy. Other alloys can also be used for manufacturing the first layer of the sandwich structure.
[0012] In an embodiment of the switching device, the ferromagnetic material is one of the group consisting of iron, nickel, cobalt, alloys of iron, nickel or cobalt, and alloys of rare - earth metals, for example, DC04, FeNi, FeCoNi or NdFeB. DC04 is a deep - drawing steel in the DC - grade steel series. FeNi is an iron - nickel alloy. FeCoNi is an iron - cobalt - nickel alloy. NdFeB is also known as neodymium magnet and is an alloy of neodymium, iron and boron. NdFeB is a permanent magnet.
[0013] In an example, the first layer and the second layer form a single piece.
[0014] In an example, the ferromagnetic material is a magnetic “soft” material or a magnetic “hard” material. A magnetic “soft” material (such as annealed iron) can be magnetized but does not tend to remain magnetized. A magnetic “hard” material tends to remain magnetized. Thus, the second layer can be implemented as a permanent magnet or can be without a permanent magnet. The ferromagnetic material is, for example, steel.
[0015] In an embodiment of the switching device, the sandwich structure includes a third layer made of a non - ferromagnetic material. The third layer and the first layer are made of the same material or of different materials. In an example, the first layer, the second layer and the third layer form a single piece. Advantageously, the third layer protects the second layer from corrosion. The second layer is fixed between the first layer and the third layer.
[0016] In the example, the sandwich structure is manufactured by arranging a first layer, a second layer, and a third layer on top of each other and fixing the three layers by a heating and pressing process. The first terminal contact and the second terminal contact are achieved by cutting the sandwich structure into strips and bending these strips. The first terminal contact is made as an integral piece, for example. The second terminal contact is made as an integral piece, for example.
[0017] In an embodiment of the switching device, the first fixed contact is located on the first layer of the first terminal contact. The second fixed contact is located on the first layer of the second terminal contact. The first fixed contact and the second fixed contact are made of silver or a silver alloy, for example. Advantageously, the materials of the first fixed contact and the second fixed contact are configured to have good electrical connection and good mechanical connection with the non-ferromagnetic material of the first layer.
[0018] In an embodiment of the switching device, the first movable contact and the second movable contact are made of silver or a silver alloy.
[0019] In an embodiment of the switching device, the first terminal contact has a terminal thickness DT. The first layer has a first thickness D1, which satisfies the following formula:
[0020] 46% DT ≤ D1 ≤ 60% DT.
[0021] In an embodiment of the switching device, the second layer has a second thickness D2, and the third layer has a third thickness D3, and the second thickness and the third thickness satisfy the following formula:
[0022] 1% DT ≤ D3 ≤ 10% DT and
[0023] D2 = DT – D1 – D3.
[0024] In an embodiment of the switching device, the terminal thickness DT is in the range of 0.8 mm to 2.5 mm or in the range of 1.0 mm to 2.0 mm.
[0025] In an embodiment of the switching device, the contact bridge has an extended length DB. The outer edge of the first movable contact and the outer edge of the second movable contact have a distance DE. The extended length DB satisfies the following formula:
[0026] DE + 5 mm < DB < DE + 20 mm or
[0027] DE + 7 mm < DB < DE + 18 mm.
[0028] In an embodiment of the switching device, both ends of the contact bridge are bent in a direction away from the first terminal contact and the second terminal contact. Therefore, when the first arc moves to the first arc angle, the length of the first arc increases.
[0029] In an embodiment of the switching device, the contact bridge is bent such that the contact bridge has a form with a first arcing angle near the first movable contact and a second arcing angle near the second movable contact.
[0030] In an embodiment, the slot motor is implemented as an electromagnetic slot motor.
[0031] In an embodiment of the switching device, the first motor part includes two plates, and the second motor part includes two additional plates. In an example, the plates and the two additional plates are made of a ferromagnetic material (such as steel).
[0032] In an embodiment, the switching device includes an arc deflector. The arc deflector is made of, for example, copper. The arc deflector is made of, for example, a single piece.
[0033] In an embodiment, the switching device includes a first arc extinguishing device. The switching device also includes a second arc extinguishing device.
[0034] In an embodiment of the switching device, the arc deflector is arranged near the first arc extinguishing device, the contact bridge, and the second arc extinguishing device. Thus, the arc deflector and a part of the first terminal contact guide the first arc towards the first arc extinguishing device.
[0035] In an embodiment, the switching device includes a magnetic drive assembly having an electric coil, a magnetic core, and an armature. The armature is movable and is coupled to the contact bridge, for example, via a contact bridge carrier of the switching device.
[0036] In an embodiment of the switching device, the first terminal contact includes a U shape, and the second terminal contact includes a U shape.
[0037] In an embodiment of the switching device, the U shape of the first terminal contact has a first arm, a second arm, and a bent portion connecting the first arm to the second arm. The first fixed contact is located at the first arm of the U shape of the first terminal contact.
[0038] In an embodiment, the switching device is implemented as a motor protection switching device (abbreviated as MPSD). The MPSD can be referred to as, for example, a motor protection circuit breaker (abbreviated as MPCB).
[0039] In an alternative embodiment, the switching device is implemented as a moulded case circuit breaker (abbreviated as MCCB).
[0040] In the example, the switching device is configured as an improved current-limiting low-voltage circuit breaker. A current-limiting feature is advantageous in order to improve the overall performance of the circuit breaker during high currents (e.g., during a short circuit) and medium currents (surge currents of inductive loads). The current-limiting feature is implemented using various means, such as reverse-loop contacts, electromagnetic coil relays, etc. Current limiting mainly helps to limit the total arc energy and the thermo-dynamic stresses applied to the system and the circuit breaker. In the case of developing a low-voltage circuit breaker, it is advantageous to reduce the manufacturing cost and to simplify the various manufacturing and assembly processes. It is also advantageous to further enhance the existing features, functions, and operating efficiency. The switching device has an improved contact system and mechanism.
[0041] In the example, reducing the arc energy is crucial for electrical safety in the workplace. An additional feature of the circuit breaker can reduce, for example, arc flash injuries by reducing the fault clearing time. In the example, the clearing time is reduced by the combined action of one or more improvements in the design. These improvements result in a significant reduction in the arcing time. In addition, the corrosion of contacts and other metals and the formation of droplets are also significantly reduced. The reduced formation of droplets avoids mechanical failures, and the shunt plates are not short-circuited due to droplets getting stuck or trapped inside them. The combined action of multiple design improvements helps to increase the magnetic pull-off force, for example, by about 20% to 30% compared to the conventional design of the switching device. This design improves the performance of the circuit breaker and its short-circuit rating. In the tests, a significant reduction in the observed arcing time was observed, for example, a reduction of 60% to 70%. BRIEF DESCRIPTION OF THE DRAWINGS
[0042] The following description of the drawings of the embodiments can further illustrate and explain aspects of the switching device. Parts and devices having the same structure and the same effect are respectively shown with equivalent reference symbols. As long as the parts and devices correspond to each other in their functional aspects in different drawings, their descriptions are not repeated for each of the following drawings.
[0043] Figures 1A to 1D An example of the switching device is shown;
[0044] Figure 2 The characteristics of different examples of the switching device are shown; and
[0045] Figure 3A and Figure 3B The slot motor of the switching device is shown. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0046] Figure 1AAn example of the switching device 10 is shown. The switching device 10 includes a first terminal contact 11 and a second terminal contact 12, a first fixed contact 13 arranged at the first terminal contact 11, a second fixed contact 14 arranged at the second terminal contact 12, a contact bridge 40, and a first movable contact 41 and a second movable contact 42 arranged at the contact bridge 40. The first terminal contact 11 and the second terminal contact 12 may be referred to as the first stationary contact and the second stationary contact. The first terminal contact 11 and the second terminal contact 12 are made of a non-ferromagnetic material (such as copper or an alloy of copper). The switching device 10 is configured to conduct and switch bidirectional or unidirectional AC current. Alternatively, the switching device 10 is configured to conduct and switch bidirectional or unidirectional DC current. The switching device 10 is configured as a circuit breaker, such as a low-voltage circuit breaker. The low voltage may be a voltage lower than, for example, 1000 VAC / 1500 VDC.
[0047] The switching device 10 includes a slot motor 50, which is implemented as an electromagnetic slot motor. The slot motor 50 has a first motor part 51 and a second motor part 52. Both the first motor part 51 and the second motor part 52 include two plates configured to enhance the magnetic field at different positions of the first arc and the second arc.
[0048] The switching device 10 includes an arc deflector 55 made of metal. The arc deflector 55 is made of ferromagnetic steel, for example, to have a better arc extending from the contact area to the arc chamber area. The arc deflector 55 is a one-piece arc deflector. The switching device 10 includes a first arc extinguishing device 61 and a second arc extinguishing device 62. The arc deflector 55 is arranged near the first arc extinguishing device 61 and the contact bridge 40. The arc deflector 55 is configured to guide the first arc 45 from the contact bridge 40 to the first arc extinguishing device 61. Similarly, the arc deflector 55 is arranged near the second arc extinguishing device 62 and the contact bridge 40. The arc deflector 55 is configured to guide the second arc 46 from the contact bridge 40 to the second arc extinguishing device 62.
[0049] The first arc extinguishing device 61 and the second arc extinguishing device 62 include a splitter plate. The first arc extinguishing device 61 and the second arc extinguishing device 62 may be referred to as the first arc chamber and the second arc chamber. The first arc extinguishing device 61 is configured to extinguish the first arc 45 generated between the first fixed contact 11 and the first movable contact 13. The second arc extinguishing device 62 is configured to extinguish the second arc 46 generated between the second fixed contact 12 and the second movable contact 14.
[0050] The switching device 10 includes a magnetic drive assembly (not shown) having an electric coil, a magnetic core, and an armature. The armature is movable and is coupled to the contact bridge 40, for example, via the contact bridge support of the switching device 10 and via the contact spring of the switching device 10. The arc deflector 55 has a form that provides space for, for example, the contact bridge support and / or the contact spring. The contact spring is located, for example, between the contact bridge support and the contact bridge 40 or between the contact bridge support and the armature.
[0051] The first terminal contact 11 includes a U shape. The U shape of the first terminal contact 11 has a first arm, a second arm, and a bent portion connecting the first arm to the second arm. The first fixed contact 13 is located at the first arm of the U shape of the first terminal contact 11. The second terminal contact 12 includes a U shape. The U shape of the second terminal contact 12 has a first arm, a second arm, and a bent portion connecting the first arm to the second arm. The second fixed contact 14 is located at the first arm of the U shape of the second terminal contact 12.
[0052] The first terminal contact 11 has a bent form such that the load current IL flowing through the first terminal contact 11, the first fixed contact 13, the first movable contact 41, and the contact bridge 40 has a U-shaped path in the on state. The first terminal contact 11 forms the first arm of the U-shaped path. The contact bridge 40 forms the second arm of the U-shaped path. The first movable contact 41 and the first fixed contact 13 are part of the coupling of the first arm and the second arm. When transitioning between the on state and the off state of the switching device 10, a first arc 45 is generated between the first fixed contact 13 and the first movable contact 41. The load current IL flowing through the first terminal contact 11, the first fixed contact 13, the first arc 45, the first movable contact 41, and the contact bridge 40 has a U shape. This U-shaped path of the load current IL results in a force that drives the first arc 45 towards the first arc extinguishing device 61.
[0053] Correspondingly, the second terminal contact 12 has a bent form such that the load current IL flowing through the contact bridge 40, the second movable contact 42, the second fixed contact 14, and the second terminal contact 12 has a U-shaped path in the on state. The contact bridge 40 forms the first arm of the U-shaped path. The second terminal contact 12 forms the second arm of the U-shaped path. The second movable contact 42 and the second fixed contact 14 are part of the coupling of the first arm and the second arm. This U-shaped path of the load current IL results in a force that drives the second arc 46 towards the second arc extinguishing device 62.
[0054] In Figure 1A , the materials of the first terminal contact 11, the second terminal contact 12, and the contact bridge 40 are, for example, copper or an alloy of copper to provide a low resistance for the current-carrying path. The materials of the first fixed contact 13, the second fixed contact 14, the first movable contact 41, and the second movable contact 42 are silver or a silver alloy.
[0055] Figure 1B shows an example of the switching device 10, which is Figure 1A a further development of the example shown. The first terminal contact 11 and the second terminal contact 12 include a sandwich structure 20 of at least a first layer 21 and a second layer 22 (which is shown in Figure 1B below Figure 1C ). The first layer 21 is made of a non-ferromagnetic material, and the second layer 22 is made of a ferromagnetic material. The non-ferromagnetic material is copper or an alloy of copper. The ferromagnetic material is one of the group consisting of iron, nickel, cobalt, an alloy of iron, nickel or cobalt, and an alloy of rare earth metals. Optionally, the sandwich structure 20 includes a third layer 23 made of a non-ferromagnetic material. The second layer 22 is disposed between the first layer 21 and the third layer 23.
[0056] Both ends of the contact bridge 40 are bent in a direction away from the first terminal contact 11 and the second terminal contact 12. The contact bridge 40 is bent such that the contact bridge 40 has the form of a first arc angle 43 near the first movable contact 41 and a second arc angle 44 near the second movable contact 42. The contact bridge 40 extends to achieve the first arc angle 43 and the second arc angle 44. The contact bridge 40 has an extended length DB. The outer edge of the first movable contact 41 and the outer edge of the second movable contact 41 have a distance DE. The extended length DB satisfies one of the following formulas, for example:
[0057] DE < DB or
[0058] DE + 5 mm < DB < DE + 20 mm or
[0059] DE + 7 mm < DB < DE + 18 mm.
[0060] The first motor part 51 of the slot motor 50 is configured to provide a magnetic field at the first fixed contact 13 and at the first movable contact 41 when the first movable contact 41 contacts the first fixed contact 13, and additionally when the first movable contact 41 is at the maximum distance from the first fixed contact 13. The first motor part 51 is configured to provide a magnetic field at the first fixed contact 13 and at the first movable contact 41 during the clearing distance of the first movable contact 41. The clearing distance refers to, for example, the distance that the contact bridge 40 moves from the closed position of the contact bridge 40 in the on state of the switching device 10 to the open position of the contact bridge 40 in the off state of the switching device 10 without a short circuit. The duration of the movement of the contact bridge 40 from the closed position of the contact bridge 40 to the open position of the contact bridge 40 is called the clearing time.
[0061] Correspondingly, the second motor part 52 of the slot motor 50 is configured to provide a magnetic field at the second fixed contact 14 and at the second movable contact 42 when the second movable contact 42 contacts the second fixed contact 14, and additionally when the second movable contact 42 is at a maximum distance from the second fixed contact 14. The second motor part 52 is configured to provide a magnetic field at the second fixed contact 14 and at the second movable contact 42 during the movement of the second movable contact 42 over the clearing distance.
[0062] The arc deflector 55 is made of copper or a copper alloy. Advantageously, due to the different surface structures of copper and iron or steel, copper allows the first arc and the second arc to move faster.
[0063] To increase the magnetic field and the arc pull-off force on the first arc 45 and the second arc 46, one ferromagnetic part or several ferromagnetic parts are located near the movable contact and the stationary contact. The position of the ferromagnetic plate and its overall dimensions have been optimized by electromagnetic simulation (abbreviated as EMAG simulation). In the case of appropriate space limitations, the side arms and legs of the arc plate cannot extend, so as to be as close as possible to the contact system. Here, the extension part of the slot motor 50 can generate or form a strong magnetic field around the arcs 45, 46.
[0064] The contact system of the switching device 10 includes U-shaped terminal contacts 11, 12. Usually, the contact material is copper to minimize the resistance between the terminals. However, in order to improve the generation of the magnetic field and to reduce the arc rest time and the arc running time, the sandwich structure 20 plays a great role. The sandwich structure 20 is realized, for example, by a three-layer composite or a three-layer complex, such as Cu-Fe-Cu.
[0065] The first arc angle 43 and the arc deflector 55 are designed such that one pole or one end of the first arc 45 extends from the first movable contact 41 via the first arc angle 43 to the arc deflector 55. Correspondingly, the second arc angle 44 and the arc deflector 55 are designed such that one pole or one end of the second arc 46 extends from the second movable contact 42 via the second arc angle 44 to the arc deflector 55. Thus, in the case of contact opening, for example in a short-circuit situation, the load current IL flows from the first contact terminal 11 via the first arc 45, the arc deflector 55 and the second arc 46 to the second contact terminal 12. Advantageously, the arc deflector 55 has a low resistance from one end to the other end of the arc deflector 55. In the example, in the case of a short circuit, the first arc angle 43 and the second arc angle 44 have mechanical contact with the arc deflector 55, or only have a small gap with the arc deflector 55. The extended arc angles 43, 44 of the contact bridge 40 also contribute to reducing the arcing time by making it easy for the arc column to transition from the contact area to the arc chamber. However, the increased weight of the contact bridge 40 may, for example, affect the contact opening acceleration.
[0066] The performance of the circuit breaker is crucial not only during high currents in short - circuit faults but also during lower currents such as overload, surge, or critical current. At lower current levels, the magnetic field generation around the contact system is also low. Therefore, the arc chambers 61, 62 cannot pull the arcs 45, 46 away from the contact tips quickly enough. As a result, the arc mobility decreases and the arc running time increases. This leads to severe corrosion of the silver - alloy contact tips. This results in faults in the form of loss of continuity or high contact resistance of the switching device 10 and temperature rise of the terminals. To verify the performance of the circuit breaker and the total arcing time, electromagnetic simulations and tests were conducted.
[0067] The function of the switching device 10 is to protect the terminal application or equipment from short - circuit and overload conditions. During overload conditions (such as lower current levels), the arc chambers cannot exert the required force on the arcs 45, 46, and the arcs 45, 46 remain on the contact tips, which leads to severe corrosion of the contact tips. This results in faults in the switching device 10 and damage to the terminal equipment. To improve the performance of the circuit breaker, it is beneficial to reduce the arcing time. This approach helps to increase the short - circuit rating of the product. These modifications are achieved using a limited space (such as the footprint of an existing product). Therefore, this redesigned approach is not a new framework for designing a new product from scratch but rather adds value to an existing product. In addition, such a design solution of the switching device 10 is cost - effective compared to conventional hybrid and solid - state circuit breaker technologies.
[0068] The ferromagnetic slot motor 50 can also be referred to as an arc - quenching coil and is typically placed near the fixed contacts 13, 14 and the moving contacts 41, 42. The slot motor 50 has no coil. The slot motor 50 has no wire. The name arc - quenching coil is derived from the U - shape of the load current IL flowing through the first terminal contact 11, the first fixed contact 13, the first arc 45 (if the first arc 45 exists), the first moving contact 41, and the contact bridge 40. The slot motor 50 enhances the magnetic field in the contact area and on the arcs 45, 46. Therefore, the movement of the arcs 45, 46 towards the arc chamber assembly is improved. As part of an experimental DoE (DoE stands for Design of Experiments) using electromagnetic simulations and laboratory tests, various design and material combinations were verified.
[0069] To reduce the total arcing time, an arc deflector 55 made of copper is more effective compared to an arc deflector 55 made of steel. The profile and ramp of the arc deflector 55 are designed to provide a smooth transition of the arc root from the arc angles 43, 44 to the raised portion of the arc deflector 55. In addition, the arc chamber pulls the arcs 45, 46 towards it, and the arcs 45, 46 can easily enter the splitter plate. Tests conducted in the laboratory also support this in terms of a significant reduction in the arcing time.
[0070] The position, profile, and overall dimensions of the slot motor 50 play a crucial role. For this circuit breaker design, the width of the slot motor 50 is optimized to cover the maximum area of the shunt plate from the main contacts 13, 14, 41, 42 to the first arc extinguishing device 61 and the second arc extinguishing device 62. Thus, the plate applies a consistent magnetic blow-off force to the arc column throughout the entire travel distance of the arcs 45 and 46. As a result, the arc running time is significantly reduced. The height of the slot motor 50 is configured such that this height can cover the entire gap where the contacts open. Thus, the blow-off force is applied along the entire height of the arc column. The three-layered contact material that implements the sandwich structure 20 significantly increases the force on the arcs 45, 46. The three-layered terminal contacts 11, 12 (Cu-Fe-Cu) are used instead of the terminal contacts 11, 12 made only of copper. The steel portion in the terminal contacts 11, 12 applies a force to the arcs 45, 46 and increases the initial acceleration of the arcs 45, 46. The percentages of the three layers 21 to 23 are based on the current density and space availability.
[0071] The switching device 10 reduces the arcing time by improving the arc quenching performance of the contact system and the arc chamber.
[0072] Figure 1C An example showing the details of the switching device 10 is Figure 1A and Figure 1B a further development of the example shown. The first terminal contact 11 has a terminal thickness DT. The first layer 21 has a first thickness D1 that satisfies the following formula:
[0073] 46% DT ≤ D1 ≤ 60% DT.
[0074] The second layer 22 has a second thickness D2, and the third layer 23 has a third thickness D3. The second thickness and the third thickness satisfy the following formula:
[0075] 1% DT ≤ D3 ≤ 10% DT and
[0076] D2 = DT - D1 - D3.
[0077] The first layer 21 and the third layer 23 prevent corrosion of the second layer 22, for example. The first terminal contact 11 and the second terminal contact 12 include the same sandwich structure 20.
[0078] In an alternative embodiment (not shown), the sandwich structure 20 does not have the third layer 23. In this case, the first thickness D1 and the second thickness D2 satisfy the following formula, for example:
[0079] 46% DT ≤ D1 ≤ 60% DT.
[0080] D2 = DT - D1.
[0081] Figure 1D An example of the switching device 10 is shown in a three - dimensional view, and this example is Figure 1A and Figure 1B a further development of the example shown.
[0082] A significant reduction in the total arcing time is achieved, for example, from 8 to 9 ms is reduced to 1.6 to 1.8 ms. This minimizes the thermo - dynamic stress on the system and reduces contact corrosion. The circuit breaker can make a breaking requirement, for example, by short - circuiting.
[0083] Figure 2 Shows the characteristics of different examples of the switching device 10 implemented, such as for example as Figures 1A to 1D shown. The force F (in artificial units) is shown as a function of the load current IL (in kA). The force F is the force in the x - direction on the first arc 45 or the second arc 46 (the x - direction is indicated in Figure 1A , Figure 1B and Figure 1D . The arcs 45, 46 are in the form of arc columns. The value of the force F is calculated. The curve achieved with the switching device 10 as shown in Figure 1A is marked with A, and the curve achieved with the switching device 10 as shown in Figure 1B is marked with B.
[0084] Figure 3A Shows the slot motor 50 of the switching device 10, and this example is Figures 1A to 1D and Figure 2 a further development of the example shown. The slot motor 50 includes a first motor part 51. The second motor part 52 (not shown) of the slot motor 50 is implemented similarly to the first motor part 51 (e.g., mirrored about a vertical axis). The first motor part 51 includes a first plate 53 and a second plate 54. The first plate 53 and the second plate 54 are made of ferromagnetic material (e.g., steel). The first plate 53 is positioned at a distance from the second plate 54. Thus, the slot motor 50 includes a slot 56. The slot 56 is located between the first plate 53 and the second plate 54. The first motor part 51 is configured to provide a magnetic field at the first fixed contact 13 and at the first moving contact 41 when the first moving contact 41 contacts the first fixed contact 13 and when the first moving contact 41 is at the maximum distance from the first fixed contact 13.
[0085] The first motor part 51 is designed such that the contact bridge 40 can move inside the slot 56. A part of the first terminal contact 11 and the first fixed contact 13 are also located in the slot 56.
[0086] The slot motor 50 is implemented as an electromagnetic slot motor. Thus, the slot motor 50 does not have a permanent magnet. The slot motor 50 does not have a coil. A load current IL flows through the first terminal contact 11, the first fixed contact 13, the first arc 45, the first movable contact 41, and the contact bridge 40. According to Ampere's law or the Biot - Savart law, a magnetic field is generated by the load current IL. Since the first terminal contact 11, the first fixed contact 13, the first arc 45, the first movable contact 41, and the contact bridge 40 have a U - shape, the load current IL also has a U - shape. Thus, the magnetic field inside the U - shape is greater than the magnetic field outside the U - shape. Therefore, the first arc 45 is driven away from the first fixed contact 13 and the first movable contact 41 in the direction of the first arc extinguishing device 61. Advantageously, the load current IL generates a magnetic field concentrated on the first arc 45 by the first motor part 51.
[0087] The slot motor 50 is configured to provide a magnetic field to the first arc 45 during the first arc 45 running or traveling from the first fixed contact 13 and the first movable contact 41 to the first arc extinguishing device 61. Thus, the slot motor 50 is configured to provide a magnetic field to the first arc 45 located between a part of the first terminal contact 11 and the first arc angle 43. In addition, the slot motor 50 is configured to provide a magnetic field to the first arc 45 located between a part of the first terminal contact 11 and a part of the arc deflector 55.
[0088] The first plate 53 of the first motor part 51 has a maximum width LW in the direction from the first fixed contact 13 and the first movable contact 41 towards the first arc extinguishing device 61. The maximum width LW satisfies the following formula:
[0089] 9mm ≤ LW ≤ 18mm or
[0090] 11mm ≤ LW ≤ 16mm.
[0091] The first plate 53 of the first motor part 51 has a maximum height LH in a direction perpendicular to the maximum width LW of the first fixed contact 13 and the first movable contact 41 towards the first arc extinguishing device 61. The maximum height LH satisfies the following formula:
[0092] 6mm ≤ LH ≤ 15mm or
[0093] 8mm ≤ LH ≤ 13mm.
[0094] The thickness of the first plate 53 is in the range between 0.5mm and 4mm, for example 1mm.
[0095] The second motor part 52 ( Figure 3A not shown therein) includes two additional plates. The two additional plates are implemented like the first plate 53 and the second plate 54. The second motor part 52 operates like the first motor part 51.
[0096] Figure 3B shows the slot motor 50 of the switching device 10, which is an example of Figures 1A to 1D , Figure 2 and Figure 3A a further development of the example shown. The first motor part 51 includes a connector 57 that connects the first plate 53 to the second plate 54. Thus, the magnetic field and stability of the slot motor 50 are enhanced; however, the connector 57 occupies space in the switching device 10.
[0097] As described Figures 1A to 1D , Figure 2 , Figure 3A and Figure 3B the embodiments shown represent examples of an improved switching device 10; thus, they do not constitute a complete list of all embodiments of the improved switching device. For example, the actual switching device may differ from the embodiments shown in terms of parts, structure, material, and shape.
[0098] Reference numerals
[0099] 10 Switching device
[0100] 11, 12 Terminal contacts
[0101] 13, 14 Fixed contacts
[0102] 20 Sandwich structure
[0103] 21 - 23 Layers
[0104] 40 Contact bridge
[0105] 41, 42 Moving contacts
[0106] 43, 44 Arc angles
[0107] 45, 46 Arcs
[0108] 50 Slot motor
[0109] 51, 52 Motor parts
[0110] 53, 54 Plates
[0111] 55 Arc deflector
[0112] 56 Slots
[0113] 57 Connector
[0114] 61, 62 Arc extinguishing devices
[0115] DB Extension length
[0116] DE Distance
[0117] DT terminal thickness
[0118] D1 - D3 thickness
[0119] F force
[0120] IL load current
[0121] LH height
[0122] LW width
Claims
1. A switching device (10), comprising: - The first terminal contact (11) and the second terminal contact (12); - The first fixed contact (13), arranged at the first terminal contact (11); - The second fixed contact (14), arranged at the second terminal contact (12); - The slot motor (50), including a first motor part (51) and a second motor part (52); - The contact bridge (40); and - The first movable contact (41) and the second movable contact (42), arranged at the contact bridge (40); Wherein, the first terminal contact (11) and the second terminal contact (12) include a sandwich structure (20) of at least a first layer (21) and a second layer (22); Wherein, the first layer (21) is made of a non-ferromagnetic material, and the second layer (22) is made of a ferromagnetic material; Wherein, the first motor part (51) is configured to provide a magnetic field at the first fixed contact (13) and at the first movable contact (41) when the first movable contact (41) is in contact with the first fixed contact (13) and when the first movable contact (41) is at the maximum distance from the first fixed contact (13); and Wherein, the second motor part (52) is configured to provide a magnetic field at the second fixed contact (14) and at the second movable contact (42) when the second movable contact (42) is in contact with the second fixed contact (14) and when the second movable contact (42) is at the maximum distance from the second fixed contact (14).
2. The switching device (10) according to claim 1, wherein, The non-ferromagnetic material is copper or an alloy of copper.
3. The switching device (10) according to claim 1 or 2, wherein, The ferromagnetic material is one of the group consisting of an alloy of iron, nickel or cobalt, an alloy of rare earth metals, iron, nickel, cobalt.
4. The switching device (10) according to any one of claims 1 to 3, wherein, The sandwich structure (20) includes a third layer (23) made of a non-ferromagnetic material.
5. The switching device (10) according to claim 4, wherein, The first terminal contact (11) has a terminal thickness DT, and the first layer (21) has a first thickness D1, and the first thickness satisfies the following formula: 46%DT ≤ D1 ≤ 60%DT.
6. The switching device (10) according to claim 5, wherein, The second layer (22) has a second thickness D2, and the third layer (23) has a third thickness D3, and the second thickness and the third thickness satisfy the following formulas: 1%DT ≤ D3 ≤ 10%DT and D2 = DT – D1 – D3.
7. The switching device (10) according to any one of claims 1 to 6, wherein, The contact bridge (40) has an extended length DB, and the outer edge of the first movable contact (41) and the outer edge of the second movable contact (41) have a distance DE, and the DB and the DE satisfy the following formula: DE + 5mm < DB < DE + 20mm.
8. The switching device (10) according to any one of claims 1 to 7, wherein, Both ends of the contact bridge (40) are bent in a direction away from the first terminal contact (11) and the second terminal contact (12).
9. The switching device (10) according to any one of claims 1 to 8, wherein, The contact bridge (40) is bent such that the contact bridge (40) has the form of a first arc angle (43) near the first movable contact (41) and a second arc angle (44) near the second movable contact (41).
10. The switching device (10) according to any one of claims 1 to 9, wherein, The slot motor (50) is implemented as an electromagnetic slot motor.
11. The switching device (10) according to any one of claims 1 to 10, wherein, The first motor part (51) comprises two plates (53, 54) made of ferromagnetic material, and the second motor part (52) comprises two additional plates made of ferromagnetic material.
12. The switching device (10) according to one of claims 1 to 11, wherein, The switching device (10) comprises an arc deflector (55) made of copper.
13. The switching device (10) according to claim 12, wherein, The switching device (10) comprises a first arc quenching device (61) and a second arc quenching device (62); and wherein the arc deflector (55) is arranged near the first arc quenching device (61), the contact bridge (40), and the second arc quenching device (62).
14. The switching device according to one of claims 1 to 13, wherein, The first terminal contact (11) comprises a U shape, and the second terminal contact (12) comprises a U shape.
15. The switching device according to one of claims 1 to 14, wherein, The switching device (10) is implemented as a motor protection switching device.