Improved switchgear

Abstract

The present invention relates to an improved switchgear for low or medium voltage applications, comprising: one or more poles; at least one fixed contact and at least one movable contact for each pole, each movable contact being reversibly movable between a coupled position, in which the movable contact is coupled to the corresponding fixed contact, and a disconnected position, in which the movable contact is disconnected from the fixed contact, wherein a separation gap exists between the movable contact and the fixed contact when the movable contact is in the disconnected position. The switchgear comprises, for each pole, at least an arc transfer element made of an electrically insulating material.

Description

Technical Field

[0001] The present invention relates to a switchgear, such as a circuit breaker, a disconnector, a contactor or the like, preferably for use in a low-voltage or medium-voltage electrical system. Background Art

[0002] Switchgear such as circuit breakers, disconnectors, contactors, limiters and the like typically comprises a housing and one or more poles, associated with each pole is at least one pair of contacts (typically comprising a fixed contact and a movable contact) that can be coupled or separated from each other.

[0003] As is well known, during an opening operation of a switchgear, once the movable contact is separated from the fixed contact, an arc is generated between the movable contact and the fixed contact.

[0004] During fault protection operation, when a switchgear is opened to interrupt a large current (e.g., an overload current or a short-circuit current), a potential arc is typically diverted from the electrical contacts by the circulating current using strong electromagnetic forces. The arc can then reach a suitable arc extinguishing device designed to facilitate its extinguishing, completing the current interruption process.

[0005] In the absence of a fault, if the intensity of the interrupting current is around the nominal value, a possible arc generated in the contact area during the disconnection operation will usually be extinguished within a relatively short time, since the electromagnetic forces are still strong enough to guide the arc towards the aforementioned arc extinguishing device.

[0006] However, when the interruption current has a value below the nominal value, in particular the so-called "critical value" (e.g. between 5% and 30% of the nominal value), the electromagnetic force generated during the disconnection operation may not be strong enough to divert a possible arc between the electrical contacts. The arc may therefore remain at the separation gap between the electrical contacts.

[0007] In AC switching equipment, this phenomenon must wait for the natural zero current moment to complete the current interruption process.

[0008] However, in DC switchgear, more serious consequences may occur.

[0009] The arc between the electrical contacts may persist for a long time, which may lead to rapid degradation of the electrical contacts or even failure of the current interruption process of the switching device. Summary of the Invention

[0010] Based on the above considerations, the main object of the present invention is to provide a switchgear for a low voltage or medium voltage electrical system, which can alleviate or overcome the above disadvantages.

[0011] Within this aim, an object of the present invention is to provide a switching device in which a possible electric arc between the electrical contacts of the electrodes can be easily extinguished even when interrupting relatively low currents.

[0012] Another object of the present invention is to provide a switching device which is particularly suitable for interrupting direct current or alternating current.

[0013] Another object of the present invention is to provide a switchgear which is capable of reliable operation and which can be manufactured in an easier manner at a cost that is competitive with respect to similar switchgear of the prior art.

[0014] The above-mentioned aim and objects are achieved by a switchgear for a low or medium voltage electrical system according to the following claim 1 and dependent claims.

[0015] Generally speaking, the switchgear according to the present invention comprises:

[0016] one or more electrodes; and

[0017] At least one fixed contact and at least one movable contact are provided for each electrode. Each movable contact is reversibly movable between a coupled position, in which the movable contact is coupled to the corresponding fixed contact, and a disconnected position, in which the movable contact is disconnected from the fixed contact. When the movable contact is in the disconnected position, a separation gap exists between the movable contact and the fixed contact.

[0018] According to some embodiments of the present invention, the movable contact is reversibly movable between the coupled position and the disconnected position in opposite rotational movements.

[0019] According to other embodiments of the present invention, the movable contact is reversibly movable between the coupled position and the disconnected position in opposite linear movements.

[0020] According to the invention, the switchgear comprises, for each pole, at least one arc transfer element made of an electrically insulating material, preferably a degassing material.

[0021] Each arc transfer element of the switchgear can be switched between an inactive position and an active position, wherein the arc transfer element is not interposed between the corresponding movable contact and the corresponding fixed contact, and wherein at least a portion of the arc transfer element is interposed between the movable contact and the fixed contact at a separation gap between the movable contact and the fixed contact.

[0022] According to the present invention, when the movable contact moves from the coupled position to the disconnected position, each arc transfer element may be switched from the inactive position to the active position.

[0023] According to the present invention, when the movable contact moves from the disconnected position to the coupled position, the arc transfer element switches from the active position to the inactive position.

[0024] Preferably, the movement of the arc transfer element between the active position and the inactive position is caused by movement of the movable contact itself, or by a mechanism operatively coupled to the movable contact.

[0025] According to an important aspect of the present invention, during an opening operation of the switching device, the arc transfer element moves from the inactive position to the active position, in which the arc transfer element reaches the separation gap with a time delay relative to the movement of the movable contact, in particular relative to the moment when the movable contact is disconnected from the fixed contact.

[0026] Preferably, the minimum time delay is higher than 1 ms.

[0027] According to some embodiments of the invention, the switchgear comprises, for each pole, at least one blade of electrically insulating material.

[0028] The blade comprises a fixed portion fixed to a support surface and a flexible portion forming an arc transfer element.

[0029] The flexible portion is movable between an inactive position in which the flexible portion is not bent relative to the fixed portion and is not interposed between the movable contact and the fixed contact, and an active position in which the flexible portion is bent relative to the fixed portion and is interposed between the movable contact and the fixed contact at a separation gap therebetween.

[0030] According to other embodiments of the invention, the switchgear comprises, for each pole, at least one shaped plunger of electrically insulating material forming the arc transfer element and elastic means operatively coupling said plunger to the fixed support.

[0031] Each plunger is reversibly movable between an inactive position in which it is not interposed between the movable contact and the fixed contact, and an active position in which it is interposed between the movable contact and the fixed contact at a separation gap between the movable contact and the fixed contact.

[0032] According to other embodiments of the invention, the switchgear comprises, for each pole, at least one shaped plunger of electrically insulating material forming an arc transfer element and a motion transmission mechanism operatively coupled to the plunger and to the movable contact.

[0033] Each plunger is reversibly movable between an inactive position in which it is not interposed between the movable contact and the fixed contact, and an active position in which it is interposed between the movable contact and the fixed contact at a separation gap between the movable contact and the fixed contact.

[0034] Preferably, the switchgear according to the present invention is suitable for installation in a DC or AC electrical system, such as a DC or AC power distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Other features and advantages of the present invention will become more apparent from the description of a preferred, but not exclusive, embodiment of an arc chamber for a low-voltage switchgear according to the present invention, illustrated by way of example in the accompanying drawings, in which:

[0036] Figure 1 is a perspective view of a switchgear according to the present invention, which is particularly suitable for use in low-voltage electrical systems;

[0037] Figure 2 -3 schematically illustrates the general operation of the switchgear according to the present invention;

[0038] Figures 4A-4B A possible embodiment of a switchgear according to the invention is schematically shown;

[0039] Figures 5A-5B Another possible embodiment of a switchgear according to the invention is schematically shown;

[0040] Figures 6A-6B Another possible embodiment of a switchgear according to the invention is schematically shown;

[0041] Figures 7A-7B Another possible embodiment of a switchgear according to the invention is schematically shown. DETAILED DESCRIPTION

[0042] With reference to the accompanying drawings, the present invention relates to a switchgear for a low voltage or medium voltage electrical system.

[0043] For the purposes of the present invention, the term "low voltage" (LV) relates to operating voltages below 1 kV AC and 1.5 kV DC, while the term "medium voltage" (MV) relates to operating voltages above 1 kV and up to several tens of kV, for example 70 kV AC and 100 kV DC.

[0044] Figure 1 Shown is a possible embodiment of a switchgear 1. In this case, the switchgear 1 is a circuit breaker designed for a low-voltage electrical system.

[0045] In principle, however, the switching device 1 may be of a different type, such as a disconnector, a contactor or the like.

[0046] The switchgear 1 may be adapted to allow or interrupt the flow of direct or alternating current in a low voltage or medium voltage electrical system.

[0047] However, the switchgear 1 is particularly suitable for installation in DC electrical systems and, for the sake of simplicity, will be described below with particular reference to this application, without intending to limit the scope of the invention in any way.

[0048] According to the invention, the switchgear 1 comprises one or more electrodes 10. Each electrode 10 is electrically connectable to a respective conductor of an electrical line, for example a conductor electrically connecting the electrode to a power source and a conductor electrically connecting the electrode to an electrical load.

[0049] According to the invention, the switchgear 1 comprises, for each pole 10 , at least one pair of electrical contacts 20 and 30 which can be coupled to or disconnected from each other in order to allow or interrupt the flow of electric current through said pole.

[0050] In particular, the switching device 1 comprises, for each pole 10 , at least one fixed contact 20 and at least one movable contact 30 which can be coupled to or disconnected from each other.

[0051] According to some embodiments of the present invention ( Figures 5A-5B , 6A-6B, 7A-7B), the switchgear 1 includes, for each pole 10, a single fixed contact 20 and a single movable contact 30 that can be coupled or disconnected to each other (single-break configuration).

[0052] According to other embodiments of the present invention ( Figures 4A-4B ), the switchgear 1 includes, for each pole 10, a pair of fixed contacts 20 and a pair of movable contacts 30 that can be coupled or disconnected to each other (double-break configuration).

[0053] Obviously, other solutions are possible as needed.

[0054] According to the present invention, each movable contact 30 is reversibly movable between a coupled position C coupled with the corresponding fixed contact 20 and a disconnected position O separated from the corresponding fixed contact 20 .

[0055] When the switching device 1 performs an opening operation, each movable contact 30 moves from the connected position C to the disconnected position O. Such operation of the switching device serves to interrupt the current flowing along the electrode 10 .

[0056] Conveniently, when the movable contacts are in the open position O, there is a separation gap 40 between each movable contact 30 and the corresponding fixed contact 20 .

[0057] When the switching device 1 performs a closing operation, each movable contact 30 moves from the disconnected position O to the connected position C. This operation of the switching device serves to ensure the electrical continuity of the electrodes 10 and allows current to flow along said electrodes.

[0058] According to some embodiments of the present invention ( Figures 4A-4B , 6A-6B, 7A-7B), each movable contact 30 is reversibly movable between its coupled position C and its disconnected position O by performing an appropriate reverse rotational movement.

[0059] According to other embodiments of the present invention ( Figures 5A-5B ), each movable contact 30 is reversibly movable between a connected position C and a disconnected position O by performing appropriate opposite linear movements.

[0060] According to some embodiments of the present invention, the switchgear 1 may include an arc chamber (not shown) having an inner volume, in which the fixed contact 20 and the movable contact 30 are located.

[0061] According to some embodiments of the present invention, for each pole, the switchgear 1 further comprises an arc extinguishing device 70 comprising a plurality of shaped arc extinguishing plates 70B. Preferably, the arc extinguishing device 70 is located in the arc chamber, close to the fixed contact 20 and the movable contact 30.

[0062] Generally, the electrical contacts 20 and 30 of the switchgear, any possible arc extinguishing device 70 and / or any possible arc extinguishing chamber can be realized according to solutions of known type and will be described below for the sake of brevity only with respect to the aspects that are of interest to the invention.

[0063] The switchgear 1 may also comprise various other components (most of which are not shown in the drawings), which may be implemented according to known types of solutions. In addition, for the sake of brevity, these additional components will not be described below.

[0064] An important distinguishing feature of the present invention is that, for each pole 10 , the switchgear 1 comprises at least one arc transfer element 50 .

[0065] Each arc transfer element 50 is conveniently made of an electrically insulating material, such as a plastics material.

[0066] Preferably, arc transfer element 50 is made of a gas-releasing material such as PTFE.

[0067] Each arc extinguishing element 50 is switchable between an inactive position A1 in which the arc extinguishing element is not interposed between the corresponding movable contact 30 and the corresponding fixed contact 20, and an active position A2 in which the arc extinguishing element is interposed at the separation gap 40 between the electrical contacts 20 and 30 ( Figure 2 ) is at least partially interposed between the corresponding movable contact 30 and the corresponding fixed contact 20.

[0068] According to the present invention, each arc transfer element 50 is switched from the inactive position A1 to the active position A2 when the corresponding movable contact 30 moves from the connected position C to the disconnected position O.

[0069] According to some embodiments of the present invention ( Figures 4A-4B , 5A-5B, 6A-6B), each arc transfer element 50 is arranged so that its movement from the inactive position A1 to the active position A2 is caused by the movement of the corresponding movable contact 30 from the connected position C to the disconnected position O.

[0070] According to other embodiments of the present invention ( Figures 7A-7B ), each arc transfer element 50 is moved by a motion transmission mechanism that operates when the corresponding movable contact 30 moves from the connected position C to the disconnected position O.

[0071] According to the present invention, each arc transfer element 50 is switched from the active position A2 to the inactive position A1 when the corresponding movable contact 30 moves from the coupled position C to the disconnected position O.

[0072] Preferably, the movement of each arc transfer element 50 from the active position A2 to the inactive position A1 is caused by the corresponding movable contact 30 when the corresponding movable contact 30 moves from the disconnected position O to the connected position C.

[0073] According to some embodiments of the present invention ( Figures 4A-4B , 5A-5B, 6A-6B), the movable contact 30 can drive the arc transfer element 50 in a direct manner, that is, by directly exerting a force on the corresponding arc transfer element 50.

[0074] According to some embodiments of the present invention ( Figures 7A-7B ), the movable contact 30 can apply its driving action to the arc transfer element 50 through an actuating device or through a motion transmission mechanism.

[0075] According to some embodiments of the present invention ( Figures 4A-4B , 5A-5B, 7A-7B), for each pole 10, the switchgear 1 includes a plurality (preferably a pair) of arc transfer elements 50 operatively associated with each pair of electrical contacts 20 and 30.

[0076] According to other embodiments of the present invention ( Figures 6A-6B ), the switchgear 1 comprises, for each pole 10 , a single arc transfer element 50 operatively associated with each pair of electrical contacts 20 and 30 .

[0077] Figures 3A to 3D It is schematically shown how the arc transfer element 50 operates during an opening operation of the switchgear 1 .

[0078] In the above figures, a pole 10 of a switchgear 1 is schematically shown. For simplicity, it is assumed that the pole 10 comprises only a fixed contact 20, a movable contact 30 and an arc transfer element 50 operatively associated with the electrical contacts 20 and 30.

[0079] Initially, it is assumed that the movable contact 30 and the corresponding fixed contact 20 are in the coupling position C ( Figure 3A ). Therefore, the current can flow along the electrode 10. In this case, the corresponding arc transfer element 50 (at Figures 3A-3B ) is in its inactive position A1 and it does not interact with the operation of the electrode 10.

[0080] It is now assumed that the switching device 1 performs an opening operation.

[0081] Such operation may be performed under fault conditions, ie with the purpose of interrupting a fault current flowing along the electrode 10 (eg an overload current or a short-circuit current having a value much higher than the nominal value expected by the switchgear).

[0082] However, this operation can also be performed in the absence of a fault condition, ie with the purpose of interrupting the current at a lower nominal value.

[0083] As described above, when the switchgear 1 performs the disconnection operation and the movable contact 30 moves away from its connected position C to reach the disconnected position O ( Figure 3B ), an arc is typically generated at the separation gap 40 between the electrical contacts 20 and 30.

[0084] If an opening operation is performed under fault conditions, the arc moves away from the separation gap 40 between the electrical contacts 20, 30 in a very short time (typically less than 1 millisecond). This is essentially due to the strong electromagnetic forces generated by the high current circulating along the electrodes 10, as described above.

[0085] The same occurs when a current with an intensity near the nominal value flows along the electrodes when a disconnection operation is performed in the absence of a fault condition.

[0086] On the contrary, if the opening operation is carried out in the presence of a so-called "critical current", the arcs tend to remain at the separation gap 40 between the electrical contacts 20, 30, since the magnetic forces generated by the current circulating along the electrode 10 are not strong enough to move these arcs away.

[0087] For the sake of clarity, it is specified that the term "critical current" means a current having an intensity lower than the nominal value provided for the switching device but higher than a threshold value, which depends on the type of switching device.

[0088] As an example, the critical current may take a value within a range between 5% and 30% of the nominal value, or a value within a similar range.

[0089] During the opening operation of the switchgear, when the movable contact 30 moves from the coupled position C to the disconnected position O, the arc transfer element 50 moves from the inactive position A1 to the active position A2. In this case, the arc transfer element 50 is interposed between the fixed contact 20 and the movable contact 30 at the separating gap 40, thereby partially blocking the separating gap.

[0090] The arc transfer element 50 is made of an electrically insulating material which interferes with the conductive path followed by a possible arc existing at the separating gap 40 , thereby disrupting said arc.

[0091] The arc transfer element 50 can thus lead to an increase in the length of the arc, thereby reducing the circulating current and facilitating the arc extinguishing process ( Figure 3C ). In addition, the arc transfer element 50 may also cause a displacement of the arc, so that the arc moves away from the electrical contacts 20 and 30, for example towards a possible arc extinguishing device 70 operatively associated with the electrical contacts 20 and 30 ( Figure 3D ).

[0092] In view of the above, it is apparent that the arc transfer element 50 is particularly effective when the switchgear 1 performs an opening operation to interrupt a critical current flowing along an electrode.

[0093] In fact, in this case, the probability of having the arcs stay in the area between the electrical contacts 20 and 30 (separating gap 40 ) is very high, and the arc transfer element 50 can effectively disturb them, thus facilitating their extinguishing.

[0094] It has been shown that the arc transfer element 50 does not need to form a partition wall through the arc chamber in order to exert its arc disrupting effect.

[0095] When the arc transfer element 50 is in its active position A2, the arc transfer element 50 only needs to be positioned at the separation gap 40 without occupying any other space. This allows reducing the overall size of the electrode 10 and greatly simplifies the design of the arc transfer element 50.

[0096] According to a preferred embodiment of the present invention, the movement of the arc transfer element 50 from the inactive position A1 to the active position A2 has a time delay relative to the separation of the movable contact 30 from the fixed contact 20. More specifically, during the opening operation of the switchgear, when the arc transfer element 50 moves from the disconnected position A1 to the disconnected position A2, there is a time delay between the moment the arc transfer element 50 reaches the separation gap 40 and the moment the movable contact 30 is disconnected from the fixed contact 20.

[0097] Preferably, the minimum said time delay is higher than 1 ms.

[0098] The above-mentioned time delay can be obtained by delaying the moment when the arc transfer element 50 starts to move relative to the movable contact or by extending the time required for the arc transfer element to reach the effective position A2, for example, by appropriately selecting the material of the arc transfer element 50, or by arranging a suitable actuation device or mechanism to move the arc transfer element 50.

[0099] According to some possible solutions, the arc transfer element 50 may be formed of a flexible sheet of electrically insulating material that bends with a suitably prolonged reaction time when the movable contact 30 moves from the coupled position C to the disconnected position O.

[0100] According to other possible solutions, the arc transfer element 50 can be operably connected to a suitable elastic device or motion transmission mechanism, which can actuate the arc transfer element with a suitably extended reaction time or can extend the time required for the arc transfer element to reach the effective position A2.

[0101] Due to the above arrangement, the arc transfer element 50 reaches the active position A2 with a controlled time delay.

[0102] In this manner, if the switchgear 1 undergoes an opening operation under fault or normal conditions, the arc transfer element 50 will not be affected by a potential high-power arc because, by the time the arc transfer element 50 reaches its active position, such high-power arc has already moved away from the separation gap 40 between the electrical contacts 20 and 30. By preventing potential damage caused by high-power arcs, its reliability can be improved. Consequently, the advantage provided by the arc transfer element 50 is a significantly extended lifespan, thereby increasing the overall reliability of the switchgear.

[0103] In the following, some possible embodiments of the present invention will be briefly described.

[0104] Example 1

[0105] Figures 4A to 4B The poles 10 of the switching device 1 in an embodiment implementing a double disconnection function are schematically shown.

[0106] The electrode 10 includes a pair of fixed contacts 20 (for simplicity, Figures 4A-4B Only one fixed contact is shown in FIG) and a pair of movable contacts 30.

[0107] The movable contact 30 is arranged on the rotary contact shaft 30A in such a manner as to move with the rotational motion.

[0108] According to a solution of known type, each pair of electrical contacts 20 , 30 is operatively associated with an arc extinguishing device 70 .

[0109] According to this embodiment of the invention, a pair of arc transfer elements 50 is operatively associated with each pair of electrical contacts 20 and 30 .

[0110] The switchgear 1 comprises, for each pole 10 , a pair of blades 500 made of electrically insulating material.

[0111] Each blade 500 is conveniently arranged in a seat 70A of the arc extinguishing device 70 , the seat 70A being designed (eg having a U-shape) to allow the movable contact 30 to move around the arc extinguishing plate 70B.

[0112] Each blade 500 comprises a fixing portion 501 fixed (for example by gluing) to the support surface 72 , which in this case is the surface of the seat 70 .

[0113] Each blade 500 comprises a flexible portion 50 which is preferably pre-bent relative to said fixed portion in the rest state.

[0114] As will become apparent below, according to the invention, the flexible portion 50 of each blade 500 forms an arc transfer element.

[0115] The flexible portion 50 of each blade 500 may be in the inactive position A1 in which the flexible portion 50 is not interposed between the movable contact 30 and the fixed contact 20 .

[0116] When it is in the inactive position A1, the flexible portion 50 of each blade 500 does not bend relative to the fixed portion 501, and it stores a certain amount of elastic energy ( Figure 4A ).

[0117] The flexible portion 50 of each blade 500 is coupled to the movable contact 30 , and when it is in the coupled position C, the flexible portion is held in the inactive position A1 by the movable contact 30 .

[0118] The flexible portion 50 of each blade 500 may be in an effective position A2 in which the flexible portion 50 is interposed between the movable contact 30 and the fixed contact 20 at the separation gap 40 ( Figure 4B ).

[0119] When the movable contact 30 moves from the coupling position C to the disconnecting position O, the flexible portion 50 of each blade 500 may move between the inactive position A1 and the active position A2.

[0120] When the movable contact 30 moves from the coupled position C to the disconnected position O, the flexible portion 50 of the blade 500 disengages from the movable contact 30 and is naturally free to bend relative to the fixed portion 501 , thereby being in a released state and moving into the separation gap 40 .

[0121] Preferably, the material of the flexible portion 50 and / or its pre-bent shape and / or its coupling to the movable contact 30 are designed such that the flexible portion 50 moves relative to the movable contact 30 with minimal time delay during an opening operation of the switching device.

[0122] When the movable contact 30 moves from the coupling position C to the disconnecting position O, the flexible portion 50 of the blade 50 may move from the active position A2 to the inactive position A1.

[0123] When it returns to the coupled position C, the movable contact 30 pushes the flexible portion 50 of the blade 500 away from the separation gap 40 .

[0124] According to possible variations of this embodiment of the invention, the switchgear 1 may comprise, for each pole 10 , a different number of blades 500 made of electrically insulating material, for example a single blade 500 .

[0125] For the sake of completeness, it has been shown that if an opening operation is performed under fault or nominal conditions, the gas pressure generated by a possible high-power arc will keep the flexible portion 50 of each blade 500 in the inactive position A1 until the arc is extinguished. This will advantageously prolong the time delay of the bending of each flexible portion 50 relative to the movement of the movable contact 30.

[0126] Example 2

[0127] Figures 5A-5B The poles 10 of the switching device 1 in an embodiment implementing a single disconnect function are schematically shown.

[0128] The electrode 10 includes a fixed contact 20 and a movable contact 30. The movable contact 30 can be coupled to or disconnected from the fixed contact 20 with appropriate linear motion.

[0129] According to this embodiment of the present invention, a pair of arc transfer elements 50 are operatively associated with the electrical contacts 20 and 30 .

[0130] The switchgear 1 comprises, for each pole 10 , a pair of shaped plungers 50 made of electrically insulating material, preferably aligned along the same reference plane of movement (not shown).

[0131] Each plunger 50 forms an arc transfer element according to the present invention.

[0132] Each plunger 50 is operatively coupled to the fixed support 750 by means of resilient means 504 , such as a spring.

[0133] Each plunger 50 can be in an inactive position A1 in which it is not interposed between the movable contact 30 and the fixed contact 20 ( Figure 5A ).

[0134] When the plunger 50 is in the inactive position A1 , the corresponding elastic means 504 connected thereto are conveniently compressed and they store a certain amount of elastic energy.

[0135] Each plunger 50 is coupled to the movable contact 30 , and when it is in the coupled position C, the plunger is held in the inoperative position A1 by the movable contact 30 .

[0136] Each plunger 50 may be in an effective position A2 in which the plunger 50 is interposed between the movable contact 30 and the fixed contact 20 at the separation gap 40 ( Figure 5B ).

[0137] When the plunger 50 is in the effective position A2, the corresponding elastic device 504 connected thereto is in a released state.

[0138] Preferably, the shape of each plunger 50 can be selected to form a continuous barrier transverse to the separation gap. For example, when a pair of plungers 50 are used, the plungers can have complementary shapes (e.g., trapezoidal) to form the above-mentioned transverse barrier, such as Figures 5A-5B shown.

[0139] When the movable contact 30 moves from the coupling position C to the disconnecting position O, each plunger 50 may move between the inactive position A1 and the active position A2.

[0140] When the movable contact 30 moves from the coupled position C to the disconnected position O, each plunger 50 is disconnected therefrom and is moved into the separation gap 40 by the corresponding elastic means 504 .

[0141] Preferably, the elastic means 504 and / or the coupling of the plunger 50 to the movable contact 30 are designed such that the plunger 50 moves relative to the movable contact 30 with minimal time delay during an opening operation of the switching device.

[0142] When the movable contact 30 moves from the disconnect position O to the connect position C, each plunger 50 may move from the active position A2 to the inactive position A1.

[0143] When it returns to the coupled position C, the movable contact 30 exerts a force on the inclined contact surface of the plunger 50 and pushes the plunger 50 away from the separation gap 40 , thereby causing a corresponding compression of the elastic means 504 .

[0144] According to possible variations of this embodiment of the invention, the switchgear 1 may comprise, for each pole 10 , a different number of plungers 50 made of electrically insulating material, for example a single plunger 50 .

[0145] In the above-described embodiment of the present invention, each plunger 50 reversibly moves between the inactive position A1 and the active position A2 with appropriate opposite linear motions. However, according to possible variations, each plunger 50 may move with appropriate opposite rotational motions.

[0146] Example 3

[0147] Figures 6A-6B A pole 10 of a switching device 1 in another embodiment for realizing a single disconnection function is schematically shown.

[0148] The electrode 10 includes a fixed contact 20 and a movable contact 30. The movable contact 30 can be coupled to or disconnected from the fixed contact 20 with appropriate rotational motion.

[0149] According to this embodiment of the present invention, arc transfer element 50 is operatively associated with electrical contacts 20 and 30 .

[0150] For each pole 10 , the switchgear 1 comprises a shaped plunger 50 made of an electrically insulating material.

[0151] The plunger 50 forms the arc transfer element according to the present invention.

[0152] The plunger 50 is operatively coupled to the fixed support 750 by a resilient means 504 , such as a spring.

[0153] The plunger 50 may be in an inactive position A1 in which the plunger 50 is not interposed between the movable contact 30 and the fixed contact 20 ( Figure 6A ).

[0154] When the plunger 50 is in the inactive position A1 , the elastic device 504 connected thereto is conveniently compressed, thereby storing a certain amount of elastic energy.

[0155] The plunger 50 is coupled to the movable contact 30 , and when it is in the coupled position C, the plunger 50 is held in the inoperative position A1 by the movable contact.

[0156] The plunger 50 may be in an effective position A2 in which the plunger 50 is interposed between the movable contact 30 and the fixed contact 20 at the separation gap 40 ( Figure 6B ).

[0157] When the plunger 50 is in the effective position A2, the elastic device 504 connected thereto is in a released state.

[0158] When the movable contact 30 moves from the coupled position C to the disconnected position O, the plunger 50 may move between the inactive position A1 and the active position A2 .

[0159] When the movable contact 30 moves from the coupled position C to the disconnected position O, each plunger 50 is disconnected therefrom and is moved into the separation gap 40 by the corresponding elastic means 504 .

[0160] Preferably, the elastic means 504 and / or the coupling of the plunger 50 to the movable contact 30 are designed such that the plunger 50 moves with respect to the movable contact 30 with minimal time delay during an opening operation of the switching device.

[0161] When the movable contact 30 moves from the disconnected position O to the connected position C, the plunger 50 may move from the active position A2 to the inactive position A1.

[0162] When it returns to the coupled position C, the movable contact 30 exerts a force on the inclined contact surface of the plunger 50 and pushes the plunger 50 away from the separation gap 40 , thereby causing compression of the elastic means 504 .

[0163] According to possible variations of this embodiment of the invention, the switchgear 1 may comprise, for each pole 10, a different number of plungers 50 made of electrically insulating material, for example Figures 5A-5B A pair of plungers 50 are shown arranged.

[0164] In the above-described embodiment of the present invention, the plunger 50 reversibly moves between the inactive position A1 and the active position A2 with appropriate opposite linear motions. However, according to possible variations, the plunger 50 may move with appropriate opposite rotational motions.

[0165] Example 4

[0166] Figures 7A-7B A pole 10 of a switching device 1 in another embodiment for realizing a single disconnection function is schematically shown.

[0167] The electrode 10 includes a fixed contact 20 and a movable contact 30. The movable contact 30 can be coupled to or disconnected from the fixed contact 20 with appropriate rotational motion.

[0168] In accordance with this embodiment of the present invention, arc transfer element 50 is operatively associated with electrical contacts 20 and 30 .

[0169] For each pole 10 , the switchgear 1 comprises a shaped plunger 50 made of an electrically insulating material.

[0170] The plunger 50 (eg having a curved shape) forms an arc transfer element according to the invention.

[0171] The plunger 50 is operatively coupled to a motion transmission mechanism 503. The latter, in turn, is operatively coupled to the movable contact 30 via a suitable kinematic chain 505. In this way, the movable contact 30 can actuate the actuation mechanism 503 and, therefore, the plunger 50.

[0172] The plunger 50 may be in an inactive position A1 in which the plunger 50 is not interposed between the movable contact 30 and the fixed contact 20 ( Figure 7A ).

[0173] The plunger 50 is held in the inoperative position A1 by the movable contact 30 in the connected position C through the motion transmission mechanism 503 .

[0174] The plunger 50 may be in an effective position A2 in which the plunger 50 is interposed between the movable contact 30 and the fixed contact 20 at the separation gap 40 ( Figure 7B ).

[0175] When the movable contact 30 moves from the coupled position C to the disconnected position O, the plunger 50 may move between the inactive position A1 and the active position A2 .

[0176] When the movable contact 30 moves from the coupled position C to the disconnected position O, the motion transmitting mechanism 503 is commanded to move the plunger 50 to the effective position A2.

[0177] Preferably, the motion transmission mechanism 503 is designed such that during an opening operation of the switching device, the plunger 50 moves relative to the movable contact 30 with minimal time delay.

[0178] When the movable contact 30 moves from the disconnected position O to the connected position C, the plunger 50 may move from the active position A2 to the inactive position A1.

[0179] When it returns to the coupling position C, the movable contact 30 commands the motion transmission mechanism 503 to move the plunger 50 to the inactive position A1.

[0180] According to possible variations of this embodiment of the invention, the switchgear 1 may comprise, for each pole 10 , a different number of plungers 50 made of electrically insulating material, for example a pair of plungers 50 .

[0181] In the above-described embodiment of the present invention, the plunger 50 reversibly moves between the inactive position A1 and the active position A2 with appropriate opposite rotational movements. However, according to possible variations, the plunger 50 may move with appropriate opposite linear movements.

[0182] As will be readily appreciated by those skilled in the art, several additional variations of the above-described embodiment are possible, depending on how the arc transfer element 50 and its possible actuation means (elastic means and motion transmission mechanism) are designed.

[0183] The switchgear 1 according to the present invention fully achieves the intended aims / objects and solves the above-mentioned outstanding problems of the prior art switchgear.

[0184] Due to the arrangement of one or more arc transfer elements 50 made of an electrically insulating material, with which the electrical contacts 20 , 30 of the electrode 10 are operatively associated, the switchgear 1 exhibits an improved arc extinguishing capability.

[0185] In particular, the switching device 1 extinguishes a possible arc that occurs between the electrical contacts 20 , 30 of the electrode 10 particularly effectively when interrupting a critical current during a disconnection operation.

[0186] The switchgear 1 is particularly suitable for use in DC applications, since the one or more arc transfer elements 50 can effectively prevent possible arcs (generated by the interruption of lower DC currents, in particular critical currents) from staying for a longer time at the separation gap 40 between the electrical contacts.

[0187] However, the switchgear 1 can also be advantageously used in AC applications. In this case, the switchgear advantageously exhibits reduced commutation times (for low AC currents, in particular critical currents), since the one or more arc transfer elements 50 effectively contribute to extinguishing a possible arc at the separation gap 40 between the electrical contacts 20 and 30.

[0188] The switchgear 1 is relatively easy and cheap to manufacture at an industrial level using mature manufacturing techniques. Therefore, it can be manufactured at a cost that is competitive with similar switchgear of the prior art.

Claims

1. A switchgear (1) for low voltage or medium voltage applications, comprising: one or more electrodes (10); at least one fixed contact (20) and at least one movable contact (30) for each electrode, each movable contact being reversibly movable between a coupled position (C) in which the movable contact is coupled to the corresponding fixed contact and a disconnected position (O) in which the movable contact is disconnected from the fixed contact, wherein a separation gap (40) exists between the movable contact and the fixed contact when the movable contact is in the disconnected position (O); Characterized in that the switchgear comprises at least one arc transfer element (50) made of electrically insulating material for each electrode, each arc transfer element being switchable between an inactive position (A1) in which the arc transfer element is not interposed between the corresponding movable contact (30) and the corresponding fixed contact (20), and an active position (A2) in which at least a portion of the arc transfer element is interposed between the movable contact and the fixed contact at a separation gap (40) between the movable contact and the fixed contact, wherein, when the movable contact (30) moves from the connected position (C) to the disconnected position (O), the arc transfer element (50) switches from the inactive position (A1) to the active position (A2), When the movable contact (30) moves from the disconnect position (O) to the connected position (C), the arc transfer element (50) switches from the effective position (A2) to the ineffective position (A1). The switchgear further comprises at least one blade (500) of electrically insulating material for each electrode (10), the blade comprising a fixed portion (501) fixed to a support surface (72) and a flexible portion (50) forming an arc transfer element, wherein the flexible portion (50) is movable between an inactive position (A1) and an active position (A2), wherein in the inactive position the flexible portion does not bend relative to the fixed portion (501) and is not interposed between the movable contact (30) and the fixed contact (20), and in the active position the flexible portion bends relative to the fixed portion (501) and is interposed between the movable contact and the fixed contact at a separation gap (40) between the movable contact and the fixed contact.

2. A switchgear (1) for low voltage or medium voltage applications, comprising: one or more electrodes (10); at least one fixed contact (20) and at least one movable contact (30) for each electrode, each movable contact being reversibly movable between a coupled position (C) in which the movable contact is coupled to the corresponding fixed contact and a disconnected position (O) in which the movable contact is disconnected from the fixed contact, wherein a separation gap (40) exists between the movable contact and the fixed contact when the movable contact is in the disconnected position (O); Characterized in that the switchgear comprises at least one arc transfer element (50) made of electrically insulating material for each electrode, each arc transfer element being switchable between an inactive position (A1) in which the arc transfer element is not interposed between the corresponding movable contact (30) and the corresponding fixed contact (20), and an active position (A2) in which at least a portion of the arc transfer element is interposed between the movable contact and the fixed contact at a separation gap (40) between the movable contact and the fixed contact, wherein, when the movable contact (30) moves from the connected position (C) to the disconnected position (O), the arc transfer element (50) switches from the inactive position (A1) to the active position (A2), When the movable contact (30) moves from the disconnect position (O) to the connected position (C), the arc transfer element (50) switches from the effective position (A2) to the ineffective position (A1). The switchgear further comprises at least one shaped plunger (50) of electrically insulating material forming an arc transfer element for each electrode (10) and elastic means (504) operatively connecting the plunger to a fixed support (750), The plunger (50) is reversibly movable between an inactive position (A1) and an active position (A2), wherein in the inactive position the plunger is not inserted between the movable contact (30) and the fixed contact (20), and in the active position the plunger is inserted between the movable contact and the fixed contact at a separation gap (40) between the movable contact and the fixed contact.

3. The switchgear according to claim 1 or 2, characterized in that: The arc transfer element (50) is driven by the movable contact (30) when moving from the active position (A2) to the inactive position (A1).

4. The switchgear according to claim 1 or 2, characterized in that: The arc transfer element (50) reaches the separation gap (40) with a time delay relative to the moment when the movable contact (30) is separated from the fixed contact (20) when moving from the inactive position (A1) to the active position (A2).

5. The switchgear according to claim 4, characterized in that The minimum time delay is higher than 1ms.

6. The switchgear according to claim 2, characterized in that The plunger (50) is reversibly movable between the inactive position (A1) and the active position (A2) by reverse rotational motion.

7. The switchgear according to claim 2, characterized in that The plunger (50) is reversibly movable between the inactive position (A1) and the active position (A2) in opposite linear motions.

8. The switchgear according to claim 1 or 2, characterized in that: The movable contact (30) is reversibly movable between the coupled position (C) and the disconnected position (O) with opposite rotational movements.

9. The switchgear according to claim 1 or 2, characterized in that: The movable contact (30) is reversibly movable between the coupled position (C) and the disconnected position (O) in opposite linear motions.

10. The switchgear according to claim 1 or 2, characterized in that: The switchgear comprises an arc extinguishing device (70) for each pole, the arc extinguishing device being operatively associated with the fixed contact (20) and the movable contact (30), the arc extinguishing device comprising a plurality of shaped arc extinguishing plates (70B).

11. The switchgear according to claim 1 or 2, characterized in that: The arc transfer element (50) is made of a degassing material.

12. A DC or AC electrical system, characterized in that The DC or AC electrical system comprises a switchgear according to one or more of the preceding claims.

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