Retractable hybrid switching device

Abstract

To provide a drawable type hybrid switching device capable of overcoming or alleviating a technical problem of the latest technique.SOLUTION: A switching device for power distribution grid includes: a drawable first switching unit having one or more first electric poles; a drawable second switching unit having one or more second electric poles and electrically connected in series to the first switching unit; and a controller mounting with control countermeasures orientated to improve the safety of a drawing operation of the first and second switching units.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to switching devices for power distribution grids, such as circuit breakers or similar type devices. [Background technology]

[0002] As is known, low voltage switching devices are used in electrical circuits or power distribution grids to enable the correct operation of specific sections of the electrical circuit or specific sections of the power distribution grid. For example, these devices are used to ensure the availability of nominal current required for some equipment, enable the proper insertion and removal of electrical loads, and protect the power distribution grid and associated electrical loads against fault events, such as overloads, short circuits, etc. (particularly circuit breakers).

[0003] Most conventional switching devices include electromechanical switching units with one or more electric poles, each of which has a pair of electric contacts that are adapted to connect or disconnect to allow or interrupt line current along the electric pole. Although they have proven to be very robust and reliable, electromechanical switching devices exhibit relatively long interruption times in DC applications, primarily at relatively high voltages (between 1 kV and 1.5 kV DC). As a result, electric arcs that usually occur between the separated electric contacts can last for a relatively long time. This often leads to severe wear of the electric contacts, resulting in a significant decrease in operational reliability and electrical durability.

[0004] To overcome these technical problems, they have designed switching devices (also called solid-state circuit breakers "SSCBs") that include, for each electrical pole, a switching unit having one or more solid-state switches, i.e., semiconductor-based transistors or thyristors adapted to operate in a conducting state that allows current flow or in a blocking state that interrupts current flow. The main advantage of SSCBs is that they have a potentially unlimited electrical endurance, depending on the circumstances, in which the interruption operation is performed without the formation of an electric arc. Furthermore, their interruption time is much shorter than that of electromechanical switching devices. A significant drawback of SSCBs is that they generally cannot provide electrical isolation between line conductors connected to each other. Indeed, when a voltage is applied to the power terminals of a solid-state switch (e.g., the collector and emitter terminals of an IGBT), a leakage current usually flows, even if the switch is in the blocking state.

[0005] Recently, they have evolved into switching devices that include an SSCB switching unit and an electromechanical switching unit, electrically connected in series. These switching devices (commonly called "hybrid switching devices") make it possible to fully exploit all the advantages offered by SSCBs in terms of reliability and reduced interruption times, and in addition, they also allow electrical isolation between the line conductors connected to each other.

[0006] As is known, many hybrid switching devices are of the "extractable" type. In this case, both the SSCB switching unit and the electromechanical switching unit are movable relative to the fixed part of the switching device. Specifically, each switching unit is mounted on a carriage so that it can be reversibly moved between an inserted position and an extracted position relative to the fixed part of the switching device. Hybrid switching devices of the extractable type have further advantages in terms of efficiency and safety of use. In fact, both the SSCB switching unit and the electromechanical switching unit can be moved to the extracted position to easily perform testing or maintenance in the field with the switching units completely disconnected from the line conductors. Summary of the Invention [Problem to be solved by the invention]

[0007] However, these switching devices also have some aspects to improve, particularly with regard to the coordinated control of the SSCB switching unit and the electromechanical switching unit in operation. With the control solutions currently employed, these switching devices cannot operate in a completely safe manner in some situations, for example when the switching devices are unable to receive an external auxiliary power supply to supply internal low-voltage components such as electrical circuits, actuators, controls, etc. The main goal of the present invention is to provide a hybrid switching device of extractable type that makes it possible to overcome or alleviate the above-mentioned technical problems of the state of the art. [Means for solving the problem]

[0008] Within this goal, the object of the present invention is to provide a switching device which ensures a high level of safety and efficiency in its operation. Another object of the present invention is to provide a switching device whose operation can be easily controlled without providing complex and expensive control resources. Another object of the present invention is to provide a switching device that is relatively easy and inexpensive to manufacture on an industrial scale. [Effects of the Invention]

[0009] This aim and these objects, together with other objects which will become apparent from the following description and the accompanying drawings, are achieved by the switching device of the invention according to claim 1 and its dependent claims set out below. [Brief explanation of the drawings]

[0010] [Figure 1] 1 shows diagrammatically a switching device according to the invention; [Figure 2] 2 illustrates diagrammatically the operation of a switching device according to the invention; [Figure 3] 2 illustrates diagrammatically the operation of a switching device according to the invention; [Figure 4] 2 illustrates diagrammatically the operation of a switching device according to the invention; [Figure 5] 2 illustrates diagrammatically the operation of a switching device according to the invention; [Figure 6] 2 illustrates diagrammatically the operation of a switching device according to the invention; DETAILED DESCRIPTION OF THE INVENTION

[0011] The switching device of the present invention comprises one or more first line terminals electrically connectable to corresponding first line conductors of electric wires, one or more second line terminals electrically connectable to corresponding second line conductors of electric wires, and a first switching unit having one or more first electrical poles, each first electrical pole comprising a first pole contact for electrically connecting to a corresponding first line terminal, a second pole contact, and one or more solid-state switches electrically connected to the first and second pole contacts, the solid-state switches operable to pass current in a conducting state or to interrupt current in a blocking state. The first switching unit is reversibly switchable between a closed state in which the solid-state switch is conducting and an open state in which the solid-state switch is blocking. The first switching unit is reversibly movable between an inserted state in which the first pole contact is coupled to the first line terminal and a withdrawn state in which the first pole contact is separated from the first line terminal.

[0012] The switching device of the present invention comprises a second switching unit having one or more second electric poles, each of which comprises a third pole contact for electrically connecting to a corresponding second pole contact of the first switching unit, a fourth pole contact for electrically connecting to a corresponding second line terminal, and electrical contacts electrically connected to the third and fourth pole contacts, the electrical contacts being configured to operate in a connected state for passing current or a disconnected state for blocking current. The second switching unit is reversibly switchable between a closed state in which the electrical contacts are connected and an open state in which the electrical contacts are disconnected. The second switching unit is reversibly movable between an inserted state in which the fourth pole contact is connected to the second line terminal and a withdrawn state in which the fourth pole contact is separated from the second line terminal.

[0013] According to the present invention, a control device for the switching device is provided to control the first switching unit and the second switching unit so that both the first switching unit and the second switching unit are in an open state when the power supply stage is in a fault state. Preferably, the control device is arranged to instruct the first switching unit and the second switching unit to switch to or remain in an open state in response to receiving a detection signal indicating that the power supply stage is in a fault condition. Preferably, the switching device comprises power supply detection means arranged to provide a detection signal to the control device indicative of the operating state of the power supply stage.

[0014] According to one aspect of the invention, a control device of the switching device is arranged to control the operating configuration of the first and second switching units such that the first and second switching units operate in a combination according to a first operating configuration, a second operating configuration or a third operating configuration; the first operating configuration corresponds to a closed state of the switching device in which both the first switching unit and the second switching unit are closed; a second operating configuration corresponding to a standby state of the switching device in which the first switching unit is in an open state and the second switching unit is in a closed state; A third operating configuration corresponds to an open state of the switching device in which both the first switching unit and the second switching unit are in an open state.

[0015] A controller is provided to control the first and second switching units such that the first and second switching units are in a third operating configuration when the power supply stage experiences a fault condition. Preferably, the control device is configured to instruct the first switching unit and the second switching unit to switch to or maintain the third operating configuration in response to receiving a detection signal indicating that the power supply stage is in a fault condition. Preferably, when the first switching unit and the second switching unit operate in combination according to the first operating mode, the control device instructs the first and second switching units to switch to the second operating mode and subsequently to switch to the third operating mode in response to receiving a detection signal indicating that the power supply stage is in a fault state.

[0016] Preferably, when the first and second switching units operate in combination according to the second operating mode, the control device commands the first and second switching units to switch to the third operating mode in response to receiving a detection signal indicating that the power supply stage is in a fault state. Preferably, when the first and second switching units operate in a combination according to the third operating mode, the control device commands the first and second switching units to maintain the third operating mode in response to receiving a detection signal indicating that the power supply stage is in a fault state.

[0017] According to one aspect of the invention, the switching device comprises a first actuator adapted to move the first switching unit upon activation by a user at least during an operation of withdrawing the first switching unit. According to one aspect of the invention, the switching device comprises a second actuator arranged to move the second switching unit upon activation by a user at least during an operation of withdrawing the second switching unit.

[0018] According to one aspect of the invention, a controller for a switching device comprises an interface section including one or more input ports arranged to receive input commands indicating a desired operating state for the switching device. Preferably, the switching device comprises a human machine interface arranged to be in communication with the interface unit, the human machine interface arranged to provide input commands upon interaction with a user.

[0019] Preferably, the interface section is capable of receiving input commands from a remote computer device. According to one aspect of the invention, the control device for the switching device is included in the first switching unit.

[0020] Further features and advantages of the present invention will become more clearly apparent from the description of preferred but non-exclusive embodiments thereof, which are described purely by way of example and not of limitation in the accompanying drawings, in which: FIG.

[0021] Referring to the aforementioned drawings, the present invention relates to a switching device 100 for an electrical power distribution grid, such as a circuit breaker, disconnector, contactor, or the like. The switching device 100 is particularly suitable for incorporation into low voltage electrical power distribution grids or systems. However, it may also be successfully employed in medium voltage electrical power distribution grids or systems. 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 higher operating voltages up to several tens of kV, for example up to 72 kV AC and 100 kV DC.

[0022] In general, the switching device 100 is arranged to be electrically connected to an electric line 50. The electric line 50 typically comprises one or more first line conductors 51 and one or more second line conductors 52, the first line conductors 51 being electrically connectable to an equivalent power source (e.g., a power supply system or a power generation system or a part of a distribution grid) and the second line conductors 52 being connectable to an equivalent electrical load (e.g., an electrical system or an electrical device or a part of a distribution grid). In the embodiment shown in the cited drawings, the electric line 50 is of the three-phase type; however, in principle, it can include a different number of phases.

[0023] The switching device 100 comprises one or more first line terminals 91 arranged to be electrically connected to corresponding first line conductors 51 of the electric wires 50, and one or more second line terminals 92 arranged to be electrically connected to corresponding second line conductors 52 of the electric wires 50. Conveniently, the first line terminal 91 and the second line terminal 92 are housed in a fixed section of the switching device (not shown), which section is conveniently delimited by a support frame (not shown) of the switching device.

[0024] The switching device 100 comprises a first switching unit 1 of the SSCB type and a second switching unit 2 of the electromechanical type, which in operation are electrically connected in series between the above-mentioned line terminals 91, 92. The first switching unit 1 comprises one or more first electric poles 1A. The number of electric poles of the first switching unit can vary as required. In the embodiment shown in the cited drawings, the first switching unit is of a three-phase type and comprises three electric poles. However, according to other embodiments of the invention (not shown), the first switching unit can comprise a different number of electric poles.

[0025] Each electrical pole 1A is arranged to be electrically connected to a corresponding first line conductor 51 of the electric wire 50 and to be electrically connected to an electrical pole of the second switching unit 2. Each electrical pole 1A comprises a first pole contact 11 and a second pole contact 12, the first pole contact being arranged to be electrically connected to a corresponding first line terminal 91 of the switching device and the second pole contact being arranged to be electrically connected to a corresponding pole contact 23 of the second switching unit 2.

[0026] Each electrical pole 1A includes one or more solid-state switches 10 configured to operate in a conducting state to pass current and in a blocking state to block current. The solid-state switches 10 (“SSCBs”) may include, for example, MOSFETs, insulated gate bipolar transistors (“IGBTs”), gate turn-off thyristors (“GTOs”), integrated gate commutated thyristors (“IGCTs”), or the like. The solid-state switches 10 of each electrical pole 1A are electrically connected between pole contacts 11 and 12, for example, in a series configuration or other more complex circuit configurations of known types.

[0027] In operation, the first switching unit 1 can be reversibly switched between a closed state (ON) and an open state (OFF), where in the closed state the solid-state switch 10 of the electrical pole 1A is conducting, and in the open state the solid-state switch 10 of the electrical pole 1A is blocking. When the first switching unit 1 is in the closed state (ON), line current can flow along the electrical pole 1A. On the other hand, when the switching unit 1 is in the open state (OFF), line current cannot flow along the electrical pole 1A. However, the expected leakage current that normally affects a solid-state switch in the blocking state will still flow.

[0028] A transition from the closed state ON to the open state OFF forms an opening operation of the first switching unit 1, while a transition from the open state OFF to the closed state ON forms a closing operation of the first switching unit 1. The first switching unit 1 may perform the opening or closing operation upon receiving a first trip signal T1 from the controller 3. Preferably, the first switching unit 1 includes one or more first drive circuits (not shown) arranged to receive the first trip signal T1 and drive a control terminal (e.g., a gate terminal or a base terminal) of the solid-state switch 10 in response to the first trip signal T1.

[0029] The second switching unit 2 comprises one or more second electric poles 2A. Also, in this case, the number of electric poles 2A of the switching unit 2 may vary as required. In general, the number of electric poles 2A corresponds to the number of electric poles 1A of the first switching unit 1. Each electrical pole 2A is arranged to be electrically connected in series with a corresponding electrical pole 1A of the first switching unit 1 and to be electrically connected to a corresponding second line conductor 52 of the electric wire 50. Accordingly, each electrical pole 2A comprises a third pole contact 23 and a fourth pole contact 24, the third pole contact 23 being arranged to be electrically connected to a corresponding second pole contact 12 of the first switching unit 1, and the fourth pole contact 24 being arranged to be electrically connected to a second line terminal 92 of the switching device.

[0030] Each second electrical pole 2A comprises an electrical contact 20 which is operable to pass current in a coupled state or to interrupt current in a separated state. Advantageously, the electrical contact 20 of each electrical pole 2A comprises a fixed electrical contact and a movable electrical contact (not shown). Each movable contact can move into or out of engagement with a fixed contact. In operation, the second switching unit 2 can reversibly switch between a closed state ON and an open state OFF, in which the electrical contacts 20 of the electrical pole 2A are coupled, and in which the electrical contacts 20 of the electrical pole 2A are separated.

[0031] When the second switching unit 2 is in the closed state ON, the line current can flow along the electrical pole 2A, while when the second switching unit 2 is in the open state OFF, the line current cannot flow along the electrical pole 2A. A transition from the closed state ON to the open state OFF constitutes an operation to open the second switching unit 2 , whereas a transition from the open state OFF to the closed state ON constitutes an operation to close the second switching unit 2 .

[0032] Preferably, the second switching unit 2 comprises one or more trip actuators 25 (which may be of a known type) arranged to cause actuation of a movable contact of said switching unit to perform the above-mentioned opening and closing operations. By way of example, the trip actuators 25 may comprise an open coil actuator 25A and a close coil actuator 25B, the open coil actuator 25A being arranged to cause actuation of a movable contact of the electrical pole 2A to perform the opening operation, and the close coil actuator being arranged to cause actuation of a movable contact of the electrical pole 2A to perform the closing operation. The trip actuator 25 may be operatively linked to a suitable actuating mechanism (not shown) arranged to move the movable contact of the second switching unit 2. Such an actuating mechanism (which may be of a known type) is conveniently adapted to move the movable contact of the second switching unit 2 upon actuation by the trip actuator described above.

[0033] The second switching unit 2 may perform an opening or closing operation based on receiving a trip signal T2 from the controller. Preferably, the second switching unit 2 may include one or more second drive circuits (not shown) arranged to receive the above-mentioned trip signal T2 and drive the trip actuator 25 based on said trip signal. When driven in accordance with the trip signal T2, the trip actuator 25 activates the above-mentioned actuating mechanism which moves the movable contact of the second switching unit to perform a closing or opening operation of the second switching unit.

[0034] Preferably, the second switching unit 2 comprises one or more contact detection means 26 arranged to provide the control device with a detection signal S1 indicative of the operating state of the second switching unit 2. By way of example, the detection means 26 may comprise a close microswitch (which may be of a known type) arranged to signal a closed state ON of the switching unit 2, and an open microswitch (which may be of a known type) arranged to signal an open state OFF of the switching unit 2.

[0035] According to the invention, the switching device 100 is of the extractable type, so that both the first switching unit 1 and the second switching unit 2 can be extracted from their normal operating position in order to disconnect the electric wire 50. The first switching unit 1 can be reversibly moved between an inserted state A and a pulled-out state B, and in the inserted state A the first pole contact 11 is connected to the first line terminal 91, and in the pulled-out state B the first pole contact 11 is separated from the first line terminal 91.

[0036] Preferably, when in the inserted state A, the first switching unit 1 has the second pole contact 12 connected to the third pole contact 23 of the second switching unit 2. Preferably, when in the extracted state B, the first switching unit 1 has the second pole contact 12 separated from the third pole contact 23 of the second switching unit 2. A transition from the inserted state A to the extracted state B constitutes an operation to extract the first switching unit, while a transition from the extracted state B to the inserted state A constitutes an operation to insert the first switching unit. When in the pulled-out position B, the first switching unit 1 may be in a test position in which the first switching unit 1 is electrically disconnected from the electrical line 50 but the first switching unit 1 is still electrically connected to the power supply stage of the switching device and has its low voltage components supplied by the power supply stage, and in the fully pulled-out position the first switching unit 1 is electrically disconnected from all electrical circuits.

[0037] Preferably, the switching apparatus 100 comprises a first carriage (not shown) on which the first switching unit 1 is mounted. Conveniently, such first carriage is slidably connected to a support frame of the switching apparatus 100. In this way, both the first switching unit 1 and the first carriage are movable relative to the fixed part of the switching apparatus.

[0038] The switching device 100 comprises a first actuation device 7 (which may be of a known type) arranged to move the first switching unit 1 upon activation by a user (e.g., activation via a suitable command button) to perform at least the operation of withdrawing the first switching unit. According to a preferred embodiment of the present invention, the first actuation device 7 is arranged to move the first switching unit 1 upon activation by the user (e.g., via an appropriate command button) even during the operation of inserting the first switching unit 1.

[0039] According to another embodiment of the present invention, the operation of inserting the switching unit 1 may be performed directly by a user, for example using a mechanical tool that can be operably connected to a suitable kinematic chain operably connected to the switching unit 1 and the support frame of the switching device. Relative to the first switching unit 1, the second switching unit 2 can be reversibly moved between an inserted state A and a pulled-out state B, in which the fourth pole contact 24 is connected to the second line terminal 92 in the inserted state A, and in which the fourth pole contact 24 is not connected to the second line terminal 92 in the pulled-out state B.

[0040] Preferably, when in the inserted state A, the second switching unit 2 has a third pole contact 23 that is connected to the second pole contact 12 of the first switching unit 1. Preferably, when in the extracted state B, the second switching unit 2 has a third pole contact 23 that is separated from the second pole contact 12 of the first switching unit 1. The transition from the inserted state A to the extracted state B constitutes an operation to extract the switching unit 2, while the transition from the extracted state B to the inserted state A constitutes an operation to insert the switching unit 2. When in the pulled out position B, the switching unit 2 may be in a test position in which the switching unit 2 is electrically disconnected from the electrical line 50 but the switching unit 2 is still electrically connected to the power supply stage of the switching device and the switching unit 2 has its low voltage components supplied by the power supply stage, and in the fully pulled out position the switching unit 2 is electrically disconnected from all electrical circuits.

[0041] Preferably, the switching apparatus 100 comprises a second carriage (not shown) on which the switching unit 2 is mounted. Conveniently, such second carriage is slidably connected to the support frame of the switching apparatus 100, so that the second carriage (together with the second switching unit 2) can move relative to the fixed part of the switching apparatus.

[0042] The switching device 100 comprises a second actuation device 8 (which may be of a known type) arranged to move the second switching unit 2 upon activation by the user (e.g., activation via an appropriate command button) at least in the operation of pulling out the second switching unit 2. According to some embodiments of the present invention, the second actuation device 8 is arranged to move the second switching unit 2 upon activation by the user (e.g., activation via an appropriate command button) even during the operation of inserting the second switching unit 2. According to some embodiments of the present invention, the act of inserting the switching unit 2 may be performed directly by a user, for example using a mechanical tool that can be operably coupled to a suitable kinematic chain that is operably connected to the switching unit 2 and the support frame of the switching apparatus.

[0043] FIG. 2 shows diagrammatically the operating configurations that the switching unit 100 can assume when an operation to withdraw or insert the switching unit 1, 2 is performed. According to Configuration #1, both switching units 1 and 2 are in inserted state A. According to Configuration #2, switching unit 1 is in pulled-out state B and switching unit 2 is in inserted state A. In this case, switching unit 1 may be in the test position or in the fully pulled-out position depending on the need. In order for the switching device to transition from mode #1 to mode #2, it is necessary to perform an operation to withdraw only the first switching unit 1. In order for the switching device to transition from mode #2 to mode #1, it is necessary to perform an operation to insert only the first switching unit 1.

[0044] According to configuration #3, the first switching unit 1 is in the inserted state A and the second switching unit 2 is in the extracted state B. In this case, the second switching unit 2 may be in the test position or in the fully extracted position depending on the need. In order for the switching device to transition from mode #1 to mode #3, it is necessary to perform an operation to withdraw only the second switching unit 2. In order for the switching device to transition from mode #3 to mode #1, it is necessary to perform an operation to insert only the second switching unit 2.

[0045] According to configuration #4, both switching units 1 and 2 are in the extended state. In this case, each of switching units 1 and 2 may be in the test position or in the fully extended position depending on the need. In order for the switching device to transition from mode #2 to mode #4, an operation to withdraw only the second switching unit 2 must be performed. In order for the switching device to transition from mode #4 to mode #2, an operation to insert only the second switching unit 2 must be performed. In order for the switching device to transition from mode #3 to mode #4, an operation to withdraw only the first switching unit 1 must be performed. In order for the switching device to transition from mode #4 to mode #3, an operation to insert only the first switching unit 1 must be performed.

[0046] In principle, the switching device 100 may take any of the above-mentioned forms depending on the need. However, the operation of pulling out the switching units 1 and 2 can be performed only when the switching units 1 and 2 are in a certain operating state. Specifically, the operation of pulling out each of the switching units 1 and 2 can be performed only when the switching unit is in the open state OFF.

[0047] Generally, the switching units 1, 2 may include several additional elements arranged at industrial level according to solutions of known type, which in the following, for the sake of brevity, will not be described in further structural detail.

[0048] According to the invention, the switching arrangement 100 comprises a control device 3 arranged to control the operation of the switching arrangement 100, in particular the operation of the switching units 1, 2. According to some embodiments of the invention (FIG. 1), the control device 3 is an independent device that is not included in any of the switching units 1, 2. According to other embodiments of the invention (not shown), the control device 3 is included in one of the switching units 1, 2, preferably in the first switching unit 1.

[0049] Preferably, the control device 3 comprises a data processing unit 31 arranged to process and provide data or control signals for implementing the required functions. In general, the data processing unit 31 may include digital or analogue data processing resources such as, for example, one or more microprocessors or DPSs.

[0050] Preferably, the control device 3 comprises a trip section 32 arranged to communicate with the data processing section 31 to generate trip signals T1, T2 for controlling the operation of the switching units 1, 2. In general, the trip section 32 may include digital or analogue data processing resources, such as, for example, one or more microprocessors or DSPs.

[0051] Preferably, the control device 3 is arranged to receive and process input commands CM1, CM2, CM3 (e.g. generated by appropriate control signals) indicating desired operating states for the switching device 100 in order to control the operation of the switching units 1, 2. Preferably, the control device 3 comprises an interface section 33 including one or more input ports arranged to receive the input commands CM1, CM2, CM3. Preferably, the switching device 100 comprises a human-machine interface 5 in communication with the interface part 33 of the control device 3. The human-machine interface 5 is arranged to provide input commands CM1, CM2, CM3 upon interaction with a user. According to another embodiment of the invention (not shown), the human-machine interface 5 is included in one of the switching units 1, 2, preferably in the first switching unit 1.

[0052] According to some embodiments of the invention, the interface unit 33 of the control device 3 is arranged to communicate with a remote computer device 99 (which is generally not part of the switching device 100), for example a digital relay. Advantageously, the interface unit 33 may receive input commands CM1, CM2, CM3 from the computer device 99. Generally, the control device 3 and the human-machine interface 5 can be arranged at an industrial level according to known types of hardware solutions. Therefore, in the following, for the sake of brevity, they will not be described in further structural or electrical circuit details.

[0053] In the switching device 100, the closing or opening operation of each switching unit is generally performed depending on the desired operating state of the switching device 100. The control device 3 is therefore advantageously configured to command the execution of the opening or closing operation of each switching unit 1, 2 by generating the above-mentioned trip signals T1, T2 in response to receiving the above-mentioned input commands CM1, CM2, CM3. Also, in principle, the withdrawal and insertion operations of the switching units 1, 2 may be performed as required.

[0054] However, as mentioned above, the operation of withdrawing each switching unit 1, 2 is performed upon activation by the user only when the switching unit is in the open state OFF. Preferably, the control device 3 is configured to prevent (via suitable enabling means, not shown) the first actuation device 7 from moving the first switching unit 1 from the inserted state A to the withdrawn state B when the first switching unit 1 is in the closed state ON. Thus, the control device 3 allows the first actuation device 7 to move the first switching unit 1 from the inserted state A to the withdrawn state B only when the first switching unit 1 is in the open state OFF.

[0055] Preferably, the control device 3 is configured to prevent the first actuation device 7 from moving the first switching unit 1 from the inserted state A to the extracted state B, even when the second switching unit 2 is in the closed state ON. In this case, the control device 3 allows the first actuation device 7 to move the first switching unit 1 from the inserted state A to the extracted state B only when both switching units 1, 2 are in the open state OFF. This solution makes it possible to prevent the withdrawal of the first switching unit 1 when leakage currents are flowing along the electric poles of the switching unit due to the second switching unit 2 being in the closed state ON. In this way, it is possible to avoid discharge phenomena (due to interruption of leakage currents) at the pole contacts 11, 12 of the first switching unit, which are very dangerous for personnel working on site.

[0056] Preferably, the second actuator 8 is arranged to move the second switching unit 2 from the inserted state A to the extracted state B only if the second switching unit 2 is in the open state OFF. Conveniently, the second actuator 8 incorporates suitable enabling means (not shown) that prevent the execution of the operation of extracting the second switching unit 2 if the second switching unit 2 is in the closed state ON.

[0057] In accordance with the present invention, the switching device 100 is connected to an external auxiliary power supply V AUX and a power supply stage 4 adapted to receive and use the received voltage to supply low-voltage components (electrical or electronic) internal to the switching device, such as the control device 3, the contact actuators 25, the actuation devices 7, 8, the above-mentioned drive circuits included in the switching units 1, 2, etc. In general, an external auxiliary power supply V AUX is obtained from electrical line 50 via a suitable auxiliary power interface device (not shown), or from an external auxiliary power supply V AUX may be supplied from any external power source. If an auxiliary power interface device is present, such auxiliary power interface device (which is generally not included in the switching device) may be of a known type, and it will not be described here for the sake of brevity.

[0058] Preferably, the power supply stage 4 is connected to an external power supply voltage V AUX and one or more drive circuits arranged to receive the charging current IC from the power supply stage 4 and to provide a charging current IC used to charge a suitable energy storage means. In accordance with the present invention, the switching device 100 comprises an energy storage stage 9 electrically connected to the power supply stage 4 to receive the charging current IC from the power supply stage 4. Preferably, the energy storage stage 9 comprises a rechargeable storage means (e.g., a capacitor bank or a battery) for storing electrical energy, and a drive circuit arranged to draw electrical energy from said storage means to generate a suitable power supply voltage V. sand an appropriate interface circuit that allows the power supply stage 4 and the energy storage stage 9 to be supplied to the low-voltage internal components of the switching device. Preferably, the power supply stage 4 and the energy storage stage 9 are housed in a fixed part of the switching device. According to some embodiments of the invention, the power supply stage 4 and the energy storage stage 9 may be standalone devices. Preferably, the power supply stage 4 and the energy storage stage 9 may be integrated to form one circuit structure. Generally, the power supply stage 4 and the energy storage stage 9 may be arranged at an industrial level according to known types of solutions. Therefore, in the following, for the sake of brevity, they will not be described in further structural or electrical circuit details.

[0059] According to an important aspect of the present invention, the controller 3 is configured to control the first switching unit 1 and the second switching unit 2 such that both the first and second switching units are open when the power supply stage 4 is in a fault state. For clarity, the power supply stage 4 is identified as being in a fault state when it is unable to operate properly, e.g., when the power supply stage 4 is unable to draw external auxiliary power V for some reason. AUX In practice, a fault condition in the power supply stage 4 corresponds to the switching device being unable to receive or utilize external auxiliary power to supply its low voltage internal components.

[0060] Preferably, the control device 3 is configured to command both the first switching unit 1 and the second switching unit 2 to switch to or remain open in response to receiving a detection signal S2 indicative of a fault condition of the power supply stage 4. Preferably, the switching device 100 comprises power supply detection means 6 arranged to provide the control device 3 with a detection signal S2 indicative of the operating state of the power supply stage 4. By way of example, the detection means 6 may comprise one or more voltage or current sensors (which may be of any known type) arranged to signal a fault condition to the control device 3, e.g. if the external auxiliary power V AUX is unavailable. It will be apparent that both the first switching unit 1 and the second switching unit 2 can use the energy stored in the energy storage means 9 to perform the opening operation commanded by the controller 3 in response to a fault condition in the power supply stage 4.

[0061] In this way, the switching device 100 can be brought into a safe state (both switching units 1, 2 open) before the low-voltage internal components of the switching device (in particular the control device 3, the contact actuator 25 and the above-mentioned drive circuit) are no longer supplied with power and the switching units become inoperable. As a result of the solution provided by the invention, the switching device ensures a higher level of safety in operation: even if the power supply stage 4 falls into a fault state and the switching units 1, 2 are unable to operate for a short period of time (to carry out an operation to open them), an operation to pull out the first switching unit 1, through which a leakage current is flowing, is prevented.

[0062] According to a further aspect of the invention, the control device 3 is configured to implement a special control logic for controlling the operation of the switching device 100 by controlling the operation of the switching units 1, 2. According to such control logic, when the switching units 1, 2 are in the inserted state A, the first switching unit 1 and the second switching unit 2 may be combined in only a number of specific operating modes, each of which corresponds to a predetermined one of the operating states of the switching device 100 (FIG. 3).

[0063] Preferably, the control device 3 is arranged to control the switching units 1, 2 so that they can operate in combination only in the following operating modes: - a first operating mode [I] in which both switching units 1 and 2 are in the closed state ON; a second operating mode [X] in which the first switching unit 1 is in the open state OFF and the second switching unit 2 is in the closed state ON; - A third operating mode [O] in which both switching units 1 and 2 are in the open state OFF.

[0064] When the switching units 1 and 2 are operating according to the first operating mode [I], the line Current can flow through the electric poles 1A, 2A of the switching units 1, 2. Thus, there is electrical continuity between the first line conductor 51 and the second line conductor 52 of the electric wire 50. Therefore, the first operating mode [I] of the switching units 1, 2 is This corresponds to a closed state of 100.

[0065] When the switching units 1 and 2 are operating according to the second operating configuration [X], the first switching unit 1 is in the open state OFF, so that line current cannot flow along the electrical poles 1A and 2A of the switching units 1 and 2. Therefore, the first line conductor 51 and the second line conductor 52 of the electric wire 50 are not connected. However, the second switching unit 2 is in the closed state ON, so that leakage current associated with the solid-state switch 10 can still flow along the electrical poles 1A and 2A, so that there is no electrical isolation between the line conductors 51 and 52. The second operating configuration [X] of the switching units 1 and 2 corresponds to a standby state of the switching device 100, which is intermediate between the closed and open states.

[0066] When the switching units 1, 2 operate according to the third operating mode [O], both switching units 1, 2 are in the open state OFF, so that the line current and any possible leakage current cannot flow along the electrical poles 1A, 2A of the switching units 1, 2. The first line conductor 51 and the second line conductor 52 of the electric wire 50 are not connected, and electrical insulation between the first line conductor 51 and the second line conductor 52 is ensured. Thus, the third operating mode [O] of the switching units 1, 2 corresponds to the open state of the switching device 100.

[0067] In general, the control device 30 is configured to command the switching units 1, 2 to switch from one operating mode to another in response to receiving the above-mentioned input commands CM1, CM2, CM3 indicating a desired operating state for the switching apparatus 100. However, according to the control logic implemented in the control device 30, transitions between the operating modes of the switching units 1, 2 must always involve the second operating mode [X], which corresponds to the standby state of the switching apparatus 100 (FIG. 3). In other words, the control device 3 is configured to control the switching units 1, 2 to prevent direct transitions between the first operating mode [I] and the third operating mode [O] of the switching units 1, 2 (FIG. 3).

[0068] Preferably, when the switching units 1, 2 are in the first operating configuration [I] (corresponding to the closed state of the switching device 100), the control device 3 commands the switching units 1, 2 to switch to the second operating configuration [X] (corresponding to the standby state of the switching device 100). In practice, according to the control logic implemented in the control device 3, the switching units 1, 2 can only switch from the first operating configuration [I] to the third operating configuration via the second operating configuration [X]. When the switching devices are in the closed state (the first operating configuration [I] of the switching units 1, 2), the switching device 100 can only switch to the open state via the standby state (the second operating configuration [X] of the switching units 1, 2).

[0069] Preferably, when the switching units 1 and 2 are in the second operating configuration [X] (corresponding to the standby state of the switching device 100), the control device 3 can command the switching units 1 and 2 to switch to the first operating configuration [I] (corresponding to the closed state of the switching device 100) or to switch to the third operating configuration [O] (corresponding to the open state of the switching device 100). In practice, according to the control logic implemented in the control device 3, the switching units 1 and 2 can switch from the second operating configuration [X] to either the first operating configuration [I] or the third operating configuration [O]. When the switching device 100 is in the standby state (the switching units 1 and 2 are in the second operating configuration [X]), the switching device 100 can switch to either the closed state (the switching units 1 and 2 are in the first operating configuration [I]) or the open state (the switching units 1 and 2 are in the third operating configuration [O]).

[0070] Preferably, when the switching units 1, 2 are in the third operating configuration [O] (corresponding to the open state of the switching device 100), the control device 3 can command the switching units 1, 2 to switch to the second operating configuration [X] (corresponding to the standby state of the switching device 100). In practice, according to the control logic implemented in the control device 3, the switching units 1, 2 can only switch from the third operating configuration [O] to the first operating configuration via the second operating configuration [X]. When the switching device is in the open state (the switching units 1, 2 are in the third operating configuration [O]), in response to receiving an input command CM1, CM2 indicating a desired different operating state, the switching device 100 can only switch to the closed state via the standby state (the second operating configuration [X] of the switching units 1, 2).

[0071] The above-mentioned control logic is configured to enable the operation of pulling out each switching unit 1, 2 upon activation by a user only when that switching unit is in the open state OFF. Preferably, the control device 3 is configured to prevent the operation of pulling out the first switching unit 1 (by disabling the first actuation device 7 as described above) when the first switching unit 1 and the second switching unit 2 are operating in a combination according to the first operating mode [I]. Preferably, the control device 3 is also configured to prevent the operation of pulling out the first switching unit 1 when the second switching unit 2 is in the closed state ON. In this case, the control device 3 is configured to prevent the operation of pulling out the first switching unit 1 even when the first switching unit 1 and the second switching unit 2 are operating in a combination according to the second operating mode [X], and the control device 3 is configured to enable the operation of pulling out the first switching unit 1 only when the first switching unit 1 and the second switching unit 2 are operating in a combination according to the third operating mode [O].

[0072] Preferably, the second actuation device 8 is arranged to perform the operation of withdrawing the second switching unit 2 only when the second switching unit 2 is in the open state OFF. In this case, the control device 3 is configured to activate the operation of withdrawing the first switching unit 1 only when the first switching unit 1 and the second switching unit 2 operate in combination according to the third operating mode [O].

[0073] Advantageously, the above-mentioned control logic is adapted to take into account possible fault conditions of the power supply stage 4. Preferably, the control device 3 is configured to control the first switching unit 1 and the second switching unit 2 so that the first and second switching units are in the above-mentioned third operating mode [O] when the power supply stage 4 is in a fault condition. Specifically, the control device 3 is configured to instruct the first switching unit 1 and the second switching unit 2 to switch to or maintain the third operating mode [O] in response to receiving a detection signal S2 indicating that the power supply stage 4 is in a fault condition.

[0074] Preferably, when the first switching unit 1 and the second switching unit 2 operate in the combination according to the first operating mode [I] described above, the control device 3 commands the first and second switching units to switch to the second operating mode [X] and subsequently to the third operating mode [O] in response to receiving a detection signal S2 indicating a fault condition in the power supply stage 4 (FIG. 4). When the switching devices are in a closed state (when the switching units 1 and 2 are in the first operating mode [I]), the switching device 100 automatically switches to a standby state (the second operating mode [X] of the switching units 1 and 2) and subsequently to an open state (the third operating mode [O] of the switching units 1 and 2) in response to a fault condition in the power supply stage 4.

[0075] Preferably, when the first switching unit 1 and the second switching unit 2 are operating in combination according to the above-described second operating mode [X], the control device 3 commands the switching units 1, 2 to switch to the third operating mode [O] in response to receiving a detection signal S2 indicating a fault condition in the power supply stage 4 (FIG. 5). When the switching device is in a standby state (when the switching units 1, 2 are in the second operating mode [X]), the switching device 100 automatically switches to an open state (the third operating mode [O] of the switching units 1, 2) in response to a fault condition in the power supply stage 4.

[0076] Preferably, when the first switching unit 1 and the second switching unit 2 are operating in the combination according to the above-described third operating mode [O], the control device 3 commands the switching units 1 and 2 to maintain the third operating mode [O] in response to receiving a detection signal S2 indicating that the power supply stage 4 is in a fault state (FIG. 6). When the switching devices are in the open state (when the switching units 1 and 2 are in the third operating mode [O]), the switching device 100 cannot switch to a different state (e.g., a standby state or a closed state) due to a fault state of the power supply stage 4.

[0077] It is clear from the above that, according to the control logic described above, the switching device 100 will automatically transition to a safe state (both switching units 1, 2 are in the open state) in response to a fault condition in the power supply stage 4. Also, in this case, both switching units 1, 2 can use the energy stored in the energy storage means 9 to perform the opening operation commanded by the control device 3.

[0078] The switching device 100 of the present invention offers important advantages over corresponding solutions available in the state of the art. Unlike known solutions in the state of the art, the control device 3 of the switching device 100 is configured to perform an emergency control operation in response to a fault condition in the power supply stage 4. Such an emergency control operation consists in commanding the SSCB switching unit 1 and the electromechanical switching unit 2 to switch to or remain open when the external auxiliary power supply becomes unavailable for any reason. This solution prevents the execution of an operation that would pull out the first switching unit 1, which may still be flowing when the second switching unit 2 is in the closed ON state. Thus, the switching device 100 operates safely even when the internal low-voltage components of the switching device are no longer supplied with power, as in the normal state. Furthermore, the electrical energy stored in the energy storage stage 9 is primarily used to transition the switching device to a safe state (both switching units 1 and 2 are open).

[0079] According to one aspect of the present invention, the control device 3 of the switching device is configured to control the switching device 100 to switch between a closed state (the switching units 1 and 2 are in the first configuration [I]) and an open state (the switch The control logic is configured to control the switching units 1, 2 so that they can be in a standby state (the switching units 1, 2 are in the second configuration [X]) in addition to a standby state (the switching units 1, 2 are in the third configuration [O]). Such a solution makes it possible to relax the time synchronization constraints between the switching units 1, 2 when the switching device 100 needs to perform an opening operation (i.e., a transition from a closed state to an open state) or a closing operation (i.e., a transition from an open state to a closed state). Such a control logic also provides for transitioning the switching device to a safe state (the third operating configuration [O] of the switching units 1, 2) in response to a fault event in the power supply stage 4.

[0080] Therefore, switching device 100 can operate according to a robust control logic that can improve its overall efficiency and safety. Switching device 100 is relatively easy to produce on an industrial scale and can be manufactured at a price competitive with similar state-of-the-art devices.

Claims

1. 1. A switching device for an electrical power distribution grid, comprising: the switching device comprises one or more first line terminals electrically connectable to corresponding first line conductors of the electric wires, one or more second line terminals electrically connectable to corresponding second line conductors of the electric wires, a first switching unit having one or more first electrical poles, a second switching unit having one or more second electrical poles, a control device arranged to control the operation of the switching device, and a power supply stage arranged to receive an external power supply; the first electrical pole comprises a first pole contact electrically connectable to a corresponding first line terminal, a second pole contact, and one or more solid state switches electrically connected to the first and second pole contacts; the solid-state switch is configured to operate to pass current in a conducting state or to block current in a blocking state; the first switching unit is reversibly switchable between a closed state in which the solid-state switch is in a conducting state and an open state in which the solid-state switch is in a blocking state; the first switching unit is reversibly movable between an inserted state in which the first pole contact is connected to the first line terminal and a withdrawn state in which the first pole contact is separated from the first line terminal; the second electric pole comprises a third pole contact electrically connectable to a corresponding second pole contact of the first switching unit, a fourth pole contact electrically connectable to a corresponding second line terminal, and an electric contact electrically connected to the third and fourth pole contacts; The electrical contacts are configured to operate in a connected state to pass current or in a disconnected state to interrupt current; the second switching unit is capable of reversibly switching between a closed state in which the electrical contacts are connected and an open state in which the electrical contacts are separated; the second switching unit is reversibly movable between an inserted state in which the fourth pole contact is coupled to the second line terminal and a withdrawn state in which the fourth pole contact is separated from the second line terminal; the control device comprises a data processing unit arranged to process and provide data or control signals for implementing the required functions; the control device comprising a trip section arranged to communicate with the data processing section to generate a trip signal for controlling operation of the first and second switching units; the control device is configured to control the first switching unit and the second switching unit such that both the first switching unit and the second switching unit are in an open state when the power supply stage experiences a fault condition; The control device is configured to instruct the first switching unit and the second switching unit to switch to an open state or to maintain an open state in response to receiving a detection signal indicating that the power supply stage is in a fault state.

2. 2. A switching device according to claim 1, wherein said switching device comprises power supply detection means arranged to provide said control device with a detection signal indicative of the operating state of said power supply stage.

3. the controller is arranged to control the first and second switching units such that the first and second switching units operate in combination according to a first operating configuration, a second operating configuration or a third operating configuration; a first operating configuration corresponds to a closed state of the switching device in which both the first switching unit and the second switching unit are closed; a second operating configuration corresponds to a standby state of the switching device in which the first switching unit is in an open state and the second switching unit is in a closed state; a third operating configuration corresponds to an open state of the switching device, with both the first switching unit and the second switching unit in an open state; 3. The switching device of claim 1, wherein the control device is configured to control the first switching unit and the second switching unit so that the first and second switching units are in a third operating configuration when the power supply stage is in a fault state.

4. 4. The switching device of claim 3, wherein the control device is configured to instruct the first switching unit and the second switching unit to switch to or maintain the third operating configuration in response to receiving a detection signal indicating that the power supply stage is in a fault condition.

5. 5. The switching device of claim 4, wherein when the first switching unit and the second switching unit operate in combination according to the first operating mode, the control device commands the first and second switching units to switch to the second operating mode and subsequently to switch to the third operating mode in response to receiving a detection signal indicating that the power supply stage is in a fault state.

6. 6. The switching device of claim 4 or 5, wherein when the first and second switching units operate in a combination according to the second operating mode, the control device commands the first and second switching units to switch to a third operating mode in response to receiving a detection signal indicating that the power supply stage is in a fault state.

7. A switching device as described in any one of claims 4 to 6, wherein when the first and second switching units operate in a combination according to the third operating mode, the control device instructs the first and second switching units to maintain the third operating mode in response to receiving a detection signal indicating that the power supply stage is in a fault state.

8. 8. The switching device according to any one of claims 1 to 7, comprising a first actuation device arranged to move the first switching unit upon activation by a user at least during an operation of withdrawing the first switching unit.

9. 9. The switching device according to any one of claims 1 to 8, further comprising a second actuation device arranged to move the second switching unit upon activation by a user at least during an operation of withdrawing the second switching unit.

10. 10. A switching device according to any preceding claim, wherein the control device comprises an interface section including one or more input ports arranged to receive input commands indicating a desired operating state for the switching device.

11. the switching device includes a human-machine interface that is communicable with the interface unit, 11. The switching device of claim 10, wherein the human-machine interface is configured to provide the input command based on interaction with a user.

12. 12. A switching device according to claim 10 or 11, wherein the interface unit is capable of receiving the input command from a remote computer device.

13. A switching device according to any one of claims 1 to 12, wherein the control device is included in a first switching unit.

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