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    • 专利摘要:
    direct current switching apparatus, electronic device, and method for switching an associated direct current circuit. a direct current (dc) switching apparatus is described, comprising at least a first mechanical switching device suitable for being positioned along an operating path of an associated dc circuit, comprising a fixed contact and a corresponding moving contact, which can be actuated between a closed position, in which they are coupled together and current flows along the operating path, and an open position, where they are separated from each other so as to interrupt the flow of current along the the operating path, where an arc can be ignited between the contacts during separation. the apparatus further comprises electronic means including a semiconductor device, suitable to be positioned along a secondary path and connected in parallel with the first mechanical switching device. the electronic means are configured to allow the switching of the current flow from the operating path to the secondary path, and the extinction, through the semiconductor device, of an arc that forms when the moving contact separates from the fixed contact , when the first mechanical switching device fails to extinguish such arc
    公开号:BR102014010994B1
    申请号:R102014010994-3
    申请日:2014-05-07
    公开日:2021-08-03
    发明作者:Davide Pessina；Romeo Bianchetti；Rudolf Gati；Thorsten Strassel
    申请人:Abb S.P.A.；
    IPC主号:
    专利说明:

    [001] The present invention relates to a direct current (DC) switching apparatus, an electronic device, and a method for switching a DC current that flows along an associated DC circuit.
    [002] It is already well known in the electrical sector the use of protection devices, typically current switches such as circuit breakers or disconnect switches, which are designed to switch the electrical system in which they are installed, to protect it by example of fault events such as overloads and short circuits, or to connect and disconnect a load.
    [003] Common electromechanical switching devices comprise a pair of separable contacts to form, interrupt and conduct current; in the interruption operation, a drive mechanism actuates the movable contacts to move them from a first closed position, in which they are coupled to corresponding fixed contacts, to a second open position, in which they are separated from them.
    [004] Normally, when the contacts begin to physically separate from each other, current continues to flow through the open space, by heating the insulating gas surrounding the contacts themselves, until the gas becomes ionized and becomes if conductive, that is, the so-called plasma state is reached; in this way, an arc flashes between the contacts, and this arc has to be extinguished as quickly as possible in order to permanently interrupt the current. In particular, in direct current (DC) applications, the interruption time can be quite long, and consequently the electric arcs can last for a relatively long time.
    [005] These long-lasting arcs result in severe wear of the contacts, thus significantly reducing the electrical lifetime, ie, the number of switching operations that a mechanical current switch can perform.
    [006] In particular, in order to quickly extinguish the arc and minimize these problems, it is necessary to decrease the current and with it the heating energy, below a certain threshold where the heating is not sufficient to sustain the arc; the plasma cools down and loses its conductivity.
    [007] In a low voltage DC circuit, the current is reduced by creating a neutralizing voltage higher than the applied voltage of the system. The voltage created, which exceeds the voltage of the system, must be maintained until the current is interrupted; this voltage is normally produced by dividing the arc into many short segments using a series of spacer plates.
    [008] For this purpose, for standardized geometries of low voltage circuit breakers, the arc must be moved from the ignition area, where the contacts open, to the arc chamber, where the separator plates are positioned; this is usually done by exploiting a magnetic field to generate a Lorentz force on the arc column.
    [009] This magnetic field can be generated by the same current that flows through the switching device; however, while they are able to extinguish electrical arcs quite easily with very high short-circuit currents, the currently known mechanical current switches have a lot of work to do to create voltages above a certain value, for example, from 600V to 1000V, and they have difficulties to extinguish electric arcs when switching operations are carried out with low currents, such as a few tens of amps.
    [010] In these cases, therefore, it is possible that at low currents an arc flash continues to burn the contacts, without being moved away from the contacts towards the arc separating plates; as a consequence, the voltage of the arc formed is low and the current is neither limited nor interrupted.
    [011] In some circuit breakers, an additional permanent magnet is normally required to reinforce the magnetic field acting on the arc column so as to move it to the arc separator plates; however, in this case, in addition to the problems related to cost, position and space availability for this additional component, the circuit breaker is only able to interrupt the current with a given polarity defined by the placement of the permanent magnet; if current flows in the opposite direction the arc is held in the contacts, which are worn by the arc continuously, burning them.
    [012] It is also known to use hybrid current switching devices, in which a conventional or mainly mechanical circuit breaker is connected in parallel with a current switching device based on semiconductors.
    [013] These hybrid solutions are intended to have switching operations ideally without arc, or at least the extinction of electric arcs occurs as quickly as possible.
    [014] For this purpose, when the mechanical breaker contacts have to be opened, the current is switched to the semiconductor device; in some cases, the semiconductor is tripped to its conductive state even before the mechanical breaker contacts are tripped; in other situations, the semiconductor is switched to its conductive state immediately after the mechanical breaker contacts are tripped, in order to remove the arcing from the mechanical contacts as soon as possible.
    [015] Although such hybrid solutions have a very good performance, one of their shortcomings is that the semiconductor device, when triggered to the conductive state, is always exposed to, and has to withstand, a current flow that can reach very high levels. high; thus, there is a high risk of possible damage and, in any case, as in many operating conditions the currents involved can be quite high, it is necessary to adopt particular protection schemes and/or excessively expensive components.
    [016] The present invention is aimed at overcoming these problems, in particular by efficiently extinguishing electric arcs especially at low currents, that is, when the current flow level is such that the arc does not move towards the separation plates, and the voltage of the corresponding arc is not sufficient for its self-extinguishment.
    [017] Therefore, the present invention provides a direct current ("DC") switching apparatus comprising:- At least a first mechanical switching device suitable for being positioned along an operating path of an associated DC circuit , said mechanical switching device comprising a fixed contact and a corresponding moving contact, which can be actuated between a closed position, where said contacts are coupled with one another and current flows along said operating path, and a position open, wherein said contacts are separated from one another so as to interrupt current along said operating path, wherein an arc can ignite between said contacts when said moving contact begins to separate from said fixed contact. The apparatus is characterized in that it further comprises: - Electronic means comprising at least one semiconductor device, suitable for being positioned along a secondary path and connected in parallel with said first mechanical switching device, wherein said means electronics are configured to allow the switching of current from said operating path to said secondary path, with the extinction, through said semiconductor device, of an arc that was ignited when said moving contact separated from said fixed contact , when said first mechanical switching device failed to extinguish it.
    [018] The present invention also provides a method for switching a direct current (DC) flowing along a DC circuit, comprising: - Providing along an operating path of said DC circuit at least a first device mechanical switching, having a fixed contact and a corresponding moving contact, wherein an arc can be ignited between said contacts when said moving contact begins to separate from said fixed contact. The method is characterized by the fact that it further comprises the steps of: - Providing electronic means, comprising at least one semiconductor device, which are positioned along a secondary path of said DC circuit and connected in parallel with said first device of mechanical switching; - Switch the current from said operational path to said secondary path, with the extinction, through said semiconductor device, of an arc that was ignited when said moving contact separated from said fixed contact, when the said first mechanical switching device failed to extinguish it.
    [019] Advantageously, with the apparatus and method according to the present invention, the semiconductor device is explored in a substantially different way than the prior art solutions; in fact, the entire current is switched from the nominal operating path to the secondary path in order to cause the semiconductor device to extinguish an arc that has been ignited between the mechanical contacts, only if the mechanical switching device was not able to extinguish. it.
    [020] In practice, when the contacts of the mechanical switching device separate from each other and an arc flashes between them, unlike prior art solutions where the semiconductor-based device is always activated to remove the arc quickly, according to the present invention the semiconductor-based device is actively used to extinguish the arc only if the actual operating conditions are such that the mechanical circuit breaker was not able to cause the extinction, that is, with switching operations of low current, such as in the order of a few tens of amps.
    [021] Thus, while in the prior art solutions the purpose of using semiconductor-based switching devices is to remove the arc flash from the mechanical contacts immediately, regardless of the current level and even mainly to prevent arcs from burning the contacts when the circulating current reaches high levels, in the present solution the semiconductor device is substantially prevented from operating when the current in the mechanical contacts is high, and its effective intervention to definitively extinguish the arc flash is exploited only when the current level is low.
    [022] Other features and advantages will become apparent from the description of preferred, but not exclusive, embodiments of a direct current ("DC") switching apparatus and a related method for switching a DC current associated, according to the invention, illustrated only by way of non-limiting examples in the attached drawings, in which:- Figure 1 is a block diagram schematically illustrating a possible embodiment of a DC switching apparatus according to the present invention; - Figure 2 is a block diagram schematically illustrating another embodiment of a DC switching apparatus according to the present invention; - Figure 3 is a block diagram schematically illustrating some electronic means which can be used in an embodiment of a DC switching apparatus in accordance with the present invention; - Figure 4 is a block diagram schematically illustrating some electronic means that can be used in an embodiment of a DC switching apparatus according to the present invention; - Figure 5 is a block diagram schematically illustrating another possible embodiment of a DC switching apparatus according to the present invention; Figures 6 to 8 are block diagrams schematically representing some electronic means that can be used in ways of incorporating a DC switching apparatus of according to the present invention;- Figure 9 is a perspective view showing a DC switching apparatus according to the present invention, in the version of a multi-pole circuit breaker with molded casing;- Figure 10 is a perspective view which shows the circuit breaker of figure 9 with electronic means assembled with the mechanical switching part of the circuit breaker;- figures 11a, 11b, 11c are block diagrams that illustrate schematically nt some possible ways of incorporating the connection between the various mechanical switching devices and the electronic means of the circuit breaker of figures 9 and 10; Figure 12 illustrates electronic means that can be used in a DC switching apparatus according to the present invention, implemented as an independent component such as an electronic relay; - Figure 13 shows the electronic means of Figure 12 assembled with an associated mechanical switching device; - Figure 14 is a flowchart of a method for switching a direct current flowing along an associated DC circuit, in accordance with the present invention.
    [023] It should be noted that in the detailed description below, identical or similar components, both structurally and functionally, have the same reference numbers, regardless of the fact that they are shown in different embodiments of the present invention; it should also be noted that, in order to describe the present invention clearly and concisely, the drawings may not necessarily be to scale, and certain features of the invention may be represented somewhat schematically.
    [024] In addition, when any of the terms "adapted", "arranged", "configured" or "molded" is used herein, referring to any component as a whole, or a part of a component, or the any combination of components, or even any part of a combination of components, is to be understood that the term means and respectively includes the structure, and/or configuration, and/or shape, and/or positioning of the component or related party, or combinations of components or parts thereof.
    [025] Furthermore, the term "apparatus" is here to be understood as referring to a single component or to two or more operationally separate components associated with each other, even if only at the installation site.
    [026] Finally, a DC switching apparatus according to the present invention will be described with special reference to its constructive embodiment, as an exemplary molded casing multipole circuit breaker, with no intention of limiting the possible applications to different types of switching devices, with any suitable number of phases or poles, such as modular circuit breakers, eg bipolar, etcetera.
    [027] In figure 1 is schematically represented a direct current (DC) switching device (hereinafter referred to as "apparatus"), globally indicated by the reference number 100.
    [028] The apparatus 100 comprises at least a first mechanical switching device 10 which is suitable to be positioned along a nominal operating path 200 of a DC circuit; the nominal operating path is the usual path followed by current under normal operating conditions, from a source (S) towards a load (L) to be supplied.
    [029] The mechanical switching device 10 comprises a fixed contact 11 and a corresponding moving contact 12, which can be actuated between a closed position, where contacts 11 and 12 are coupled together and current flows along the operating path 200, and an open position, where contacts 11 and 12 are spaced apart so as to interrupt current along operating path 200; as is well known, an arc can be ignited between contacts 11 and 12 when moving contact 12 begins to physically separate from fixed contact 11.
    [030] The mechanical switching device 10 can be any traditional mechanical current switch, or be part of a switch such as the mechanical break part or pole of a modular or molded housing circuit breaker such as the one illustrated by example, in figure 9.
    [031] The apparatus 100 according to the present disclosure also comprises electronic means, globally indicated by reference number 20, comprising at least one semiconductor device 21 that is positioned along a secondary path 201, connected in parallel with the first device mechanical switching 10.
    [032] For example, at least one semiconductor device 21 comprises one or more IGBTs; for example, it is possible to use a single reverse blocking IGBT (Insulated Gate Bipolar Transistor) or two semiconductor devices having a given polarity.
    [033] Advantageously, the electronic means 20 are configured to allow the communication of the current from the nominal path 200 to the secondary path 201, and to pass this current through the semiconductor device 21, in order to cause the extinction of the arc that was ignited between mechanical contacts 11 and 12 only when the first mechanical switching device 10 alone fails to extinguish the arc.
    [034] According to a preferred embodiment, the electronic means 20 are configured to allow the communication of current from the operating path 200 to the secondary path 201 through the semiconductor device 21, in order to extinguish the arc through the semiconductor device 21 only when and/or until the circulating current level is/is below a preset threshold (ILim).
    [035] As illustrated schematically in the embodiment of figure 2, the electronic means 20 comprise a non-linear resistor 30, preferably a varistor, connected in parallel with the semiconductor device 21; such non-linear resistor 30 is suitable for absorbing and dissipating energy during current switching operations, so as to allow permanent current interruption and also protect the semiconductor device 21 from possible overvoltages that occur when such semiconductor device 21 is turned off.
    [036] According to a possible embodiment, the electronic means 20 are configured to be energized by the voltage generated by the arc that was ignited between the fixed and mobile contacts, 11 and 12, when said mobile contact 12 separates from the said fixed contact 11; alternatively, the electronic means 20 can be powered by any other suitable power source.
    [037] According to an exemplary embodiment, when the apparatus 100 is installed, at least one semiconductor device 21 is in a non-conductive state when the fixed and movable contacts 11, 12 are in the closed position, i.e. under conditions operating normals, and the electronic means 20 are configured to switch the semiconductor device 21 to its current-carrying state after a first predetermined time interval (tl) has elapsed from the time the movable contact 12 began to separate. of the corresponding fixed contact 11.
    [038] In addition, the electronic means 20 are also configured to later switch the semiconductor device 21 from its conductive state to the non-conductive state:- after a predetermined second time interval (t2) has elapsed, with the semiconductor device 21 in its conductive state; or - when the level of current flowing through the secondary path through the semiconductor device 21 exceeds the predetermined threshold (ILim), before the second predetermined time interval (t2) has elapsed.
    [039] The first predetermined time interval (t1) and the second predetermined time interval (t2) can be selected according to the applications; for example, (t1) may be less than 500 ms, preferably between 10 and 200 ms, and (t2) may be less than 10 ms, preferably between 1 and 5 ms.
    [040] For example, the time (tl) can be selected so that when the semiconductor device 21 is turned on, the first mechanical switching device 10 has already extinguished the arc and therefore permanently interrupted the current along of the nominal path 200 (the act of turning on the semiconductor device 21 is substantially null), or, if the current is still flowing, this means that the current is too low and the mechanical switching device is not capable of extinguishing the bow. In turn, the time (t2) can be selected so as to be sufficient for switching the current and recovering the dielectric properties of the air space between mechanical contacts 11 and 12, in order to avoid re-ignition of the arc voltage in mechanical switch 10 when semiconductor device 21 is off.
    [041] As will be appreciated by those skilled in the art, the electronic means 20 can be formed by any suitable combination of available electronic components, such as those illustrated in the various figures, with essentially a drive piece 22 for turning on/off the semiconductor device. 21 and, according to the embodiment described above, one or more timers.
    [042] Furthermore, according to this embodiment and as illustrated in Figure 3, to protect the semiconductor device 21 from high-level currents and, if necessary, turn it off before the second predetermined time interval (t2) has ended, the electronic means 20 comprise voltage monitoring means 23 for monitoring the voltage through the semiconductor device 21, comparing the monitored voltage with a predetermined threshold (VLim). When the detected voltage is above the preset limit, which means that the current (Ic) flowing through the semiconductor device 21 is above the preset limit (ILim), the semiconductor device 21 is immediately switched to its non-conductive state.
    [043] Alternatively, according to an exemplary embodiment illustrated in Figure 5, the electronic means 20 comprises a resistor 24 connected in series with the semiconductor device 21 along the secondary path 201; further, as illustrated in Figure 5, the electronic means 20 comprises an inductor 25 connected in series with the semiconductor device 21 along the secondary path 201 so as to limit the rates of current rise; a diode 26 which blocks a reverse current from a single unidirectionally operationally switching semiconductor device 21 may be positioned between the semiconductor device 21 and the inductor 25.
    [044] In particular, resistor 24 is configured, for example, dimensioned, so as to block the switching of current from the operating path 200 to the secondary path 201 through the semiconductor device 21, when the current flowing along the path secondary 201 exceeds the pre-selected limit (ILim).
    [045] In practice, the arc-flash voltage for a given current is determined by the design of the mechanical interruption part. The resistor value is chosen so that the arc voltage at low currents can switch the current entirely, whereas at higher currents (> ILim) the voltage drop across the resistor due to the additional current cannot be overcome by the arc voltage.
    [046] In this way, the semiconductor experiences a current that is still admissible for the device.
    [047] As will be described in more detail below, in practice the actual percentage of current switching from the nominal path 200 to the secondary path 201 is determined by the voltage difference between the two paths, that is, between the voltage of the arc and the voltage across resistor 24.
    [048] According to this embodiment, when the apparatus 100 is installed, at least one semiconductor device 21 is also preferably in the non-conductive state when the fixed and movable contacts 11, 12 are in the closed position, i.e. , under normal operating conditions; the electronic means 20 are configured to switch the semiconductor device 21 to its current-concording state, after a first predetermined time interval (tl) has elapsed from the moment when the mobile contact 12 began to separate from the fixed contact 11 corresponding.
    [049] As in the previous embodiment, the electronic means 20 are also configured to later switch the semiconductor device 21 from the conductive state to its non-conductive state after a second predetermined time interval (t2) has elapsed, with the second semiconductor device 21 in its conductive state.
    [050] If, during switching, the level of the current switched in the secondary path 201 exceeds the predetermined threshold (ILim), as indicated above, the resistor 24 prevents the current switching above the capabilities of the semiconductor device along the secondary path 201 .
    [051] In this case, the arc is eliminated by means of the mechanical switching device 10, and the semiconductor device 21 is turned off by the associated driver 22.
    [052] In particular, according to this embodiment, and as a possible additional arrangement for the protection of the semiconductor device 21, the electronic means 20 comprise voltage monitoring means TJ comprising, for example, a voltage comparator to monitor the voltage across resistor 24; if the voltage across resistor 24 exceeds a defined threshold, semiconductor 21 is turned off and the current is then safely switched back to the nominal path 200.
    [053] In this configuration, resistor 24 therefore has a dual function, that is, it is used to block the excess current parallel to the arc, and to detect the current in the parallel secondary path 201.
    [054] Inductor 25 must be properly sized to ensure slow current switching, which is necessary for reliable voltage measurement and to allow for delays introduced by electronic control; inductor 25 limits the current switching rate for the parallel path, prevents rapid switching of current back to the arc-flash in case of semi-conductive switching operation, and allows more reliable voltage measurement over resistor 24 .
    [055] In addition, or alternatively to the above, it is also possible to monitor the level of the circulating current directly or indirectly, by monitoring the voltage created across the mechanical switching device 10.
    [056] For this purpose, the electronic means 20 may comprise means for monitoring the current level; for example, the current monitoring means comprises a voltage divider such as two resistors 28 and a transistor 29 in a voltage divider configuration as illustrated in Figure 6; the split arc voltage drives transistor 29, which maintains semiconductor device 1 in its conductive state when turned on, or maintains semiconductor device 21 in its non-conductive state when the level of monitored current exceeds the predetermined threshold.
    [057] In practice, the monitored voltage above a preselected threshold is a direct indication that arcing is occurring and therefore the switching operation is taking place at a high current. The mechanical circuit breaker is capable of operating under these conditions, and the semiconductor device is kept in its non-conductive state.
    [058] Evidently, other alternative embodiments are possible for such monitoring means, as illustrated for example in figure 7, where the transistor is replaced by a comparator 290.
    [059] Furthermore, in combination with any of the embodiments described above, the electronic means 20 may comprise an additional protection part, i.e. a damping circuit, indicated in Figure 8 by reference numeral 40, connected in parallel with the semiconductor device 21 and comprising, for example, a resistor and a capacitor. This snubber circuit 40 is suitable to avoid excessive voltage transients during the shutdown of the semiconductor device 21.
    [060] Figures 9 and 10 show a possible embodiment in which the switching apparatus 100 according to the present invention is embodied as a molded casing multipole circuit breaker; the corresponding schematic representation is illustrated in figures 11, while figure 13 shows one of the poles of the circuit breaker in figure 10, this pole being indicated by the reference number 10, connected with the electronic means 20.
    [061] As illustrated, the circuit breaker 100 comprises an enclosure 1 from which at least a first terminal and a second terminal protrude outwards, suitable for the input and output of electrical connections with the associated DC circuit, respectively ; in the illustrated version, there are four corresponding upper terminals 2 and four lower terminals 3, with only one output terminal 3 being visible in figure 13, which can be connected in a suitable manner as seen in figure 11a.
    [062] Clearly, what is illustrated in figure 11a is to be understood only as an example of a possible connection; for example, in the embodiment shown in figure 11b a load is connected to the corresponding terminals of two intermediate mechanical switching devices 10.
    [063] Figure 11c schematically illustrates another embodiment suitable for specific applications, that is, with circuits where there is a double ground fault; in this case, second electronic means 20 are provided with at least one additional corresponding semiconductor device 21, substantially identical to the one described above, associated with another mechanical switching device such as, for example, the last in the series.
    [064] According to this embodiment, the first mechanical switching device 10 is positioned inside the housing 1 and, in practice, consists of one of the circuit breaker poles, such as pole 10 of figure 13; in particular, in the exemplary embodiment illustrated in Figures 9 to 11, the circuit breaker 100 comprises a plurality of first mechanical switching devices 10 housed within the housing 1 and connected in series with each other, as schematically shown in Figure 11. In practice, each current switching device 10 is constituted by a corresponding pole of the circuit breaker, such as the illustrated pole 10, and comprises at least one fixed contact 11 and a corresponding moving contact 12, which can be actuated so as to move from there. from an initial closed position, where it is coupled with its associated fixed contact 11, to an open position, where the movable contact 12 is separated from the associated fixed contact 11.
    [065] As depicted in Figure 11, the semiconductor device 21 is connected in parallel with at least one of the plurality of first mechanical switching devices 10.
    [066] In this embodiment, a complete galvanic isolation can be performed without the need for additional switches outside the enclosure 1.
    [067] The electronic means 20 comprising the semiconductor device 21 may be positioned inside or outside the housing 1.
    [068] As illustrated, for example, in Figure 12, the electronic means 20 with at least one semiconductor device 21 can be positioned on a support plate 210, housed in a container 220, thus taking the form of an independent component. Such a component can be accommodated inside the housing 1, as shown in figure 10, for example, with the connecting pins 102 of the pole 101 mating with the corresponding input 211 provided in the support plate 210, as illustrated in figure 13.
    [069] Alternatively, the electronic means 20 can be positioned at the installation site, separate from the first mechanical switching device, for example, separately from the circuit breaker 100, and can be operatively connected thereto from outside the housing 1 .
    [070] The operation of apparatus 100 will now be described with reference to the flowchart of Figure 14, which illustrates a method for switching a direct current (DC) flowing along an associated circuit, in accordance with the present invention .
    [071] In a first step 301 of method 300, at least a first mechanical switching device 10 having a fixed contact 11 and a corresponding moving contact 12 is provided along a nominal or operational path 201 of the DC circuit; as described, an arc can be ignited between contacts 11 and 12 when moving contact 12 begins to separate from fixed contact 11.
    [072] In step 301, electronic means 20 are also provided comprising at least one semiconductor device 21, positioned along a secondary path 201 of the DC circuit and connected in parallel with the first mechanical switching device 10.
    [073] As appreciated by those skilled in the art, the first mechanical switching device 10 and the electronic means 20 can be provided in step 301 simultaneously or in any order.
    [074] Under normal operating conditions, the fixed and moving contacts 11 and 12 are coupled and current flows through them along the nominal or operational path 200 of the DC circuit.
    [075] When the moving contact 12 starts to separate from the fixed contact 11 and an arc is ignited between them, the method 300 provides in step 302 the current switching and, in particular, the total current flow from the path operating 200 to the secondary path 201, causing the ignited arc to be extinguished by means of the semiconductor device 21 when the first mechanical switching device 10 fails to extinguish the arc by itself.
    [076] In particular, the switching step 302 comprises continuing to switch the current from the operating path 200 to the secondary path 201 through the semiconductor device 21 until all the current is switched, only if and up to the level current is above zero and below a preset threshold (ILim).
    [077] According to a first exemplary embodiment, the semiconductor device 21 is initially in a non-conductive state, and the switching step 302 comprises a step 303 of switching the semiconductor device 21 to its current-carrying state, then that a first predetermined time interval (tl) has elapsed from the instant when the mobile contact 12 began to separate from the corresponding fixed contact 11 .
    [078] In this way, the total current flow can be switched along the secondary path 201.
    [079] According to this embodiment, method 300 further comprises switching, later, in step 304, the semiconductor device 21 to its non-conductive state, after a second predetermined time interval (t2) has elapsed, or when the level of current flowing through the secondary path exceeds the predetermined threshold (ILim) before the second predetermined interval of time (t2) has elapsed.
    [080] Thus, in practice, if the separation of the mechanical contacts is occurring at a certain level of current, that is, with high current, for example, above 100 A, the first mechanical switching device 10 turns off the current completely and therefore the arc is removed without the need to switch the current along the secondary path 201; if, on the contrary, the separation of mechanical contacts 11 and 12 is taking place at low currents, for example between 10 and 100 A, it is possible that the first mechanical switching device 10 will not be able to extinguish the arc flash. Thus, after the first predetermined time interval (tl), the semiconductor device 21 is switched to its conductive state; the arc voltage switches the current to the parallel secondary path 201 and the nominal path 200 cools down, recovering dielectrically. After a second predetermined time interval (t2), which is generally shorter than the first (tl), during which, ideally, the total current flow is switched along the secondary path 201, the semiconductor device 21 is off, and the arc between contacts 11 and 12 is extinguished.
    [081] At the end, the current is switched to the varistor 30 and definitely turned off.
    [082] According to an alternative embodiment using, for example, the configuration apparatus of Figure 5, the current switching along the secondary path 201 is blocked thanks to resistor 24 if the current is greater than a predetermined threshold. As indicated above, this is achieved thanks to the fact that the characteristics of the mechanical switching device 10 are known and the resistor 24 is sized accordingly so that current is allowed to pass through the semiconductor device 21 only up to the circulating current. do not exceed this threshold.
    [083] In practice, in this second embodiment the switching sequence works as follows.
    [084] As in the previous embodiment, in the nominal state or under normal operating conditions the semiconductor device 21 is preferably in the non-conductive state, and the mechanical contacts 11 and 12 are coupled. After a first predetermined time interval has elapsed from the moment the contacts 11 and 12 began to separate, the semiconductor device 21 is switched to the conductive state, and the switching process is started in the presence of the arc between contacts 11 and 12. The voltage difference between the two paths, namely the arc voltage and the voltage across resistor 24, triggers the current switching. The time required is proportional to the inductance 25 and inversely proportional to the voltage difference. If the switched current does not exceed the preset threshold, for example if switching occurs at low currents, the arc voltage is greater than the voltage at resistor 24 and all current is switched to parallel path 201 so that the arc is extinguished by means of the semiconductor device 21.
    [085] In practice, the semiconductor device 21 is turned off after remaining in the conductive state for a second predefined time interval; during this second time interval, the current is switched to the parallel path and the arc-flash channel cools down. The nominal path 200 is not re-ignited, and during the semiconductor device shutdown the current is switched to the parallel varistor 30, which isolates the remaining current.
    [086] If, on the contrary, the current in the parallel secondary path 201 is sufficiently high, this means that the arc voltage will be equal to or less than the voltage across resistor 24 (neglecting the small voltage drop across the semiconductor device 21). In this case, the switching is stopped due to a lack of voltage difference to trigger the current switching, and the semiconductor device 21 can be switched off. In this condition, the current is switched back to the nominal path 201. The semiconductor is safely in its non-conductive state, and the mechanical circuit breaker is operating in a current regime such as, for example, with a high current, where it is capable of interrupting the current by itself. The parallel path 201 is therefore protected against overcurrents by resistor 24 and against known arc-flash characteristics.
    [087] It has been observed in practice that the apparatus 100, according to the present invention, allows to achieve some improvements over known solutions and, in particular, is able to solve the problem of switching operations and related arc-flash extinction that occur at low currents where a traditional DC mechanical circuit breaker can fail. Such conditions are very common, for example, in solar power plants, where higher voltages are required and many switching operations take place at low rated currents.
    [088] This result is achieved through a very simple and inexpensive structure in which low power semiconductors, for example, can be used; in addition, the frame can easily be used with different types of mechanical switching devices, such as Molded Case Circuit Breaker® circuit breakers (MCCB) or Miniature Circuit Breaker® circuit breakers (MCB), as electronic means require a very small volume and can solve the current polarity problem.
    [089] For example, figure 4 schematically shows an exemplary embodiment of a semiconductor device 21, in which two IGBTs can be used to take into account a possible polarity different from the current, since a circuit breaker 100, like that of the figure 9, is installed to operate.
    [090] Figure 5 schematically represents a bipolar DC circuit breaker, where a second mechanical switching device 10A, such as a second pole of the DC circuit breaker, is connected in parallel with a semiconductor device 21A symmetrical with respect to the semiconductor device 21, so as to ensure the bipolarity of the system in case a semiconductor is able to switch only one polarity of current. In this example, a diode 26A is also symmetrical with respect to diode 26.
    [091] Thus, thanks to the present solution, the use of permanent magnets to handle low currents is avoided.
    [092] Furthermore, as mentioned above, the electronic means 20 with the associated semiconductor device 21 can be realized as an independent component, for example, constituting or being part of an electronic relay, or such means can be a device separate electronic device, indicated in figures 10 and 12 by the reference number 400. Thus, the present invention also relates to an electronic device characterized in that it comprises electronic means 20 comprising at least one semiconductor device 21, suitable for being positioned along a secondary path 201 of an associated DC circuit, and connected in parallel with a mechanical switching device 10 suitable to be positioned along an operative path 200 of said DC circuit, where said mechanical switching device 10 comprises a fixed contact 11 and a corresponding mobile contact 12, which can be actuated between a closed position, where said contacts 11 and 12 are coupled together and current flows along said operating path 200, and an open position, wherein said contacts 11e 12 are spaced apart so as to interrupt current along said path operational, where an arc can be ignited between said contacts 11 and 12 when said moving contact 12 begins to separate from said fixed contact 11. The electronic means 20 are configured to allow switching of the total current flow from the said operating path to said secondary path, causing said semiconductor device 21 to extinguish an arc flash that ignited when said moving contact 12 separated from said fixed contact 11, (only) when said first mechanical switching device failed to extinguish the bow by itself.
    [093] The apparatus 100 and the method thus conceived are susceptible to modifications and variations, all falling within the scope of the inventive concept as described above and defined in the appended claims, including any partial or total combinations of the above-described forms of incorporation, which must be considered included in the present description, although they are not explicitly described. All details can still be replaced by other technically equivalent elements. For example, apparatus 100 has been described with reference to a molded case circuit breaker, but it can be any type of similar current protection device, such as a miniature circuit breaker (MCB), a disconnect switch, et cetera, a electronics may comprise other types of components, et cetera, under normal operating conditions, the semiconductor device may also be initially maintained in the on state, for example, according to the embodiment of figure 5.
    [094] In practice, the materials, as well as the dimensions, can be of any type, according to the needs and state of the art.
    权利要求:
    Claims (16)
    [0001]
    1. Direct current switching apparatus (100) comprising:- at least a first mechanical switching device (10) suitable to be positioned along an operating path (200) of a DC (Direct Current) circuit associated, wherein said mechanical switching device (10) comprises a fixed contact (11) and a corresponding movable contact (12), which can be actuated between a closed position, where said contacts (11, 12) are coupled to a to the other and current flows along said operating path (200), and an open position, in which said contacts (11, 12) are separated from each other, so as to interrupt the flow of current along said path operational, where an arc can be ignited between said contacts (11, 12) when said mobile contact (12) begins to separate from said fixed contact (11); the apparatus (100) further comprising:- electronic means ( 20) comprising at least one semi device conductor (21), suitable to be positioned along a secondary path (201) and connected in parallel with said first mechanical switching device (10), wherein said electronic means (20) are configured to allow the switching of the current flow from said operational path to said secondary path, extinguishing, through said semiconductor device (21), an arc that was ignited when said moving contact (12) separated from said fixed contact (11) , when said first mechanical switching device (10) fails to extinguish said arc, the apparatus being characterized in that at least one said semiconductor device (21) is in a non-conductive state when said fixed and mobile contacts (11, 12 ) are in said closed position, where said electronic means (20) are configured to switch said semiconductor device (21) to its current-carrying state, after a first predetermined time interval (tl) has elapsed from the moment when said mobile contact (12) began to separate from the corresponding fixed contact (11), and because said electronic means (20) are configured to later switch the said semiconductor device (21) to its non-conductive state, after a second predetermined time interval (t2) has elapsed, with said second semiconductor device (20) in its conductive state, or when the current level (Ic) flowing through said secondary path exceeds said predetermined threshold (ILim) before said second predetermined time interval elapses.
    [0002]
    Direct current switching apparatus according to claim 1, characterized in that said electronic means (20) are configured to allow switching of the current flow from said operational path to said secondary path, when the level circulating current is below a predefined threshold (ILim).
    [0003]
    Direct current switching apparatus according to claim 1, characterized in that said electronic means (20) comprise a non-linear resistor (30) connected in parallel with said semiconductor device (21).
    [0004]
    4. Direct current switching apparatus according to any one of the preceding claims, characterized in that said electronic means (20) comprise voltage monitoring means (23) for monitoring the voltage in said semiconductor device (21) for comparison of this voltage monitored with a predetermined threshold.
    [0005]
    Direct current switching apparatus according to any one of the preceding claims, characterized in that said electronic means (20) comprise a resistor (24) connected in series with said semiconductor device (21) along said secondary path (201), with said resistor (24) being configured to avoid switching additional current from the operating path (200) to the secondary path (201) when the current flowing along the secondary path (201) exceeds a preselected limit (ILim).
    [0006]
    Direct current switching apparatus according to any one of the preceding claims, characterized in that said electronic means (20) comprise an inductor (25) connected in series with said semiconductor device (21) along said secondary path .
    [0007]
    Direct current switching apparatus according to claim 5, characterized in that said electronic means (20) comprise voltage monitoring means (47) for monitoring the voltage over said resistor (24).
    [0008]
    8. Direct current switching apparatus according to any one of the preceding claims, characterized in that said electronic means (20) comprise means for monitoring the level of current flow, where said current monitoring means comprise two resistors ( 28) in a voltage divider configuration and a transistor (29), which maintain the semiconductor device (21) in its non-conductive state when the level of the monitored current exceeds said predetermined threshold.
    [0009]
    Direct current switching apparatus according to any one of the preceding claims, characterized in that said electronic means (20) comprise a damping circuit (40) connected in parallel with said semiconductor device (21).
    [0010]
    10. Direct current switching apparatus, according to any one of the preceding claims, characterized in that said electronic means (20) are configured to be energized by the voltage generated by the arc that is ignited between said fixed and mobile contacts (11 , 12), when said mobile contact (12) separates from said fixed contact (11).
    [0011]
    Direct current switching apparatus according to any one of the preceding claims, characterized in that it comprises an enclosure (1) from which at least a first terminal and a second terminal suitable for input and output protrude. output electrical connections with said associated DC circuit, respectively, where said first mechanical switching device (10) is positioned within said housing (1), and said electronic means (20) comprising said semiconductor device (21) are positioned inside or outside said casing (1).
    [0012]
    Direct current switching apparatus according to claim 11, characterized in that it comprises a plurality of first mechanical switching devices (10) housed within said housing (1), each of the current switching devices (10 ) having at least one fixed contact (11) and a corresponding movable contact (12), which can be actuated so as to move from an initial closed position, where it is coupled with its associated fixed contact (11) , to an open position, wherein the movable contact (12) separates from the associated fixed contact (11), where said plurality of first mechanical switching devices (10) are connected in series with one another, with said second semiconductor device (21) being connected in parallel with one of the plurality of said first mechanical switching devices (10).
    [0013]
    A method for switching a direct current circuit (300) in an apparatus as defined in claim 1, for switching direct current (DC) flowing along an associated DC circuit, comprising:- providing (301), by along an operating path of said DC circuit, at least a first mechanical switching device (10) having a fixed contact (11) and a corresponding moving contact (12), wherein an arc can be ignited between said contacts (11, 12) when said mobile contact (12) begins to separate from said fixed contact (11); characterized in that it further comprises the steps of:- providing (301) electronic means (20) comprising at least one semiconductor device (21) which is positioned along a secondary path of said DC circuit, connected in parallel with said first mechanical switching device (10); - switching (302) the current flow from said operating path to said dry path and cause, through said semiconductor device (21), the extinction of an arc that is ignited when said moving contact (12) separates from said fixed contact (12), when said first mechanical switching device ( 10) fails to extinguish such arc, said switching step (302) comprising switching (303) of said semiconductor device (21) to its current-carrying state after a first predetermined time interval has elapsed from the time when said moving contact (12) has begun to separate from the corresponding fixed contact (11).- subsequently switching (304) said semiconductor device (21) to its non-conductive state, after a second predetermined time interval has elapsed, with said second semiconductor device (20) in its conductive state, or when the level of current flowing through said secondary path exceeds a predetermined threshold before said second i npreset time interval ends.
    [0014]
    A method for switching a direct current circuit, according to claim 13, characterized in that said switching step (302) comprises switching the current flow from said operating path to said secondary path, when the level of the circulating current is greater than zero and less than a predefined threshold.
    [0015]
    A method for switching a direct current circuit according to claims 13 or 14, characterized in that said switching step (302) comprises blocking current switching from the operating path (200) to the secondary path ( 201), when the current flowing along the secondary path (201) exceeds a preselected threshold (ILim).
    [0016]
    16. Electronic device (400) comprising an apparatus as defined in claim 1, which in turn uses the method as defined in claim 13, characterized in that it comprises electronic means (20) comprising at least one semiconductor device (21) suitable for being positioned along a secondary path (201) of an associated DC circuit, connected in parallel with a mechanical switching device (10) which is suitable to be positioned along an operating path (200) of said DC circuit , wherein said mechanical switching device (10) comprises a fixed contact (11) and a corresponding movable contact (12), which can be actuated between a closed position, where said contacts (11, 12) are coupled to each other and current flows along said operating path (200), and an open position, wherein said contacts (11, 12) are separated from one another so as to stop the flow of current. along said operating path, wherein an arc can be ignited between said contacts (11, 12) when said moving contact (12) begins to separate from said fixed contact (11); and wherein said electronic means (20) are configured to allow the switching of current flow from said operating path to said secondary path, and the extinction, through said semiconductor device (21), of an arc ignited when said moving contact (12) separates from said fixed contact (11), when said first mechanical switching device fails to extinguish such arc, said semiconductor device (21) being in a non-conductive state when said fixed and movable contacts (11, 12) are in said closed position, where said electronic means (20) are configured to switch said semiconductor device (21) to its current-carrying state, after a first predetermined interval of time (tl) has elapsed from the moment when said mobile contact (12) began to separate from the corresponding fixed contact (11), and when said electronic means (20) are configured. to later switch said semiconductor device (21) to its non-conductive state, after a second predetermined time interval (t2) has elapsed, with said second semiconductor device (20) in its conductive state, or when the level of the current (Ic) flowing through said secondary path exceeds said predetermined threshold (ILim) before said second predetermined time interval elapses.
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    同族专利:
    公开号 | 公开日
    US9484168B2|2016-11-01|
    EP2801994A1|2014-11-12|
    US20140332500A1|2014-11-13|
    CN104143809A|2014-11-12|
    BR102014010994A2|2015-01-06|
    CN104143809B|2019-04-09|
    DK2801994T3|2019-04-15|
    CA2849437A1|2014-11-07|
    EP2801994B1|2019-02-20|
    IN2014CH02214A|2015-07-03|
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    法律状态:
    2015-01-06| B03A| Publication of a patent application or of a certificate of addition of invention [chapter 3.1 patent gazette]|
    2018-11-13| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|
    2020-02-18| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2021-07-06| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2021-08-03| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 07/05/2014, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    EP13166880.8A|EP2801994B1|2013-05-07|2013-05-07|DC current switching apparatus, electronic device, and method for switching an associated DC circuit|
    EP13166880.8|2013-05-07|
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