A three-phase arc extinguishing device operated by an actuator

Abstract

The present disclosure relates to a three-phase arc extinguishing device operated by an actuator. The device includes a first busbar, a second busbar, and a third busbar, each for a corresponding phase of the three-phase switchgear. The device also includes at least one piston made of a conductive material and having a tapered shape that tapers toward its front end. The device also includes only one pyrotechnic actuator, which is arranged to axially move each of the at least one piston until the first busbar, the second busbar, and the third busbar are all short-circuited to each other via the at least one piston when the pyrotechnic actuator is activated.

Description

Technical Field

[0001] The present invention relates to an arc extinguishing device for a three-phase electrical switching device. Background Art

[0002] In switchgear, arcing events can cause severe damage even for relatively short durations. Arcs can be quenched by short-circuiting all phases to each other (and optionally to ground). To protect switchgear components and avoid damage, the duration of the arc should be reduced. Circuit breakers can interrupt fault currents caused by internal arcs. However, the opening time of circuit breakers can be relatively long, for example, 30 to 60 ms. To quench the arc more quickly, for example, within 2 ms of arc detection, pyrotechnic actuators can be used.

[0003] EP 3 696 842 discloses a single-phase electrical closing switch that uses a pyrotechnic actuator to drive a movable piston to electrically connect a phase electrode and a ground electrode, thereby grounding one phase. Summary of the Invention

[0004] It is an object of the present invention to provide an arc extinguishing device for a three-phase electrical switching apparatus using only one pyrotechnic actuator.

[0005] According to one aspect of the present invention, an arc extinguishing device for a three-phase electrical switchgear is provided. The device includes a first busbar, a second busbar, and a third busbar, each busbar being used for a respective phase of the three-phase switchgear. The device also includes at least one piston made of a conductive material and having a tapered shape that tapers toward a front end of the piston. The device also includes only one pyrotechnic actuator, which, when activated, is arranged to axially move each of the at least one piston until all of the first busbar, the second busbar, and the third busbar are short-circuited to one another via the at least one piston.

[0006] According to another aspect of the present invention, a three-phase electrical switching apparatus is provided, comprising an embodiment of the arc extinguishing apparatus of the present disclosure and a fault-clearing circuit breaker arranged to disconnect current in each of three phases, the three phases being connected to a first busbar, a second busbar, and a third busbar, respectively.

[0007] By using only one pyrotechnic actuator for short-circuiting all three phases by means of at least one (e.g., one, two, or three) piston, the complexity and cost of the arc extinguishing device can be reduced. In addition, by using only one pyrotechnic actuator, there is no need to synchronize the activation of multiple pyrotechnic actuators.

[0008] It should be noted that, where appropriate, any feature of any aspect can be applied to any other aspect. Similarly, any advantage of any aspect can be applied to any other aspect. Other objects, features, and advantages of the accompanying embodiments will be apparent from the following detailed description, the appended dependent claims, and the accompanying drawings.

[0009] In general, unless otherwise expressly defined herein, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field. All references to "a / an / the element, device, component, device, step, etc." will be interpreted in an open manner as referring to at least one instance of an element, device, component, device, step, etc., unless expressly stated otherwise. Unless expressly stated otherwise, the steps of any method disclosed herein do not have to be performed in the exact order disclosed. The use of "first," "second," etc. for different features / components of the present disclosure is intended only to distinguish the features / components from other similar features / components, without assigning any continuity or hierarchy to the features / components. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The embodiments are described by way of example with reference to the accompanying drawings, in which

[0011] Figure 1 is a schematic circuit diagram of a three-phase switchgear including an arc extinguishing device according to some embodiments of the present invention.

[0012] Figure 2 is a schematic diagram of a longitudinal cross-section of a piston arranged with a pyrotechnic actuator according to some embodiments of the present invention.

[0013] Figure 3a is a schematic diagram of a longitudinal cross-section of a piston of an arc extinguishing device arranged in an open position relative to a first busbar, a second busbar, and a third busbar according to some embodiments of the present invention.

[0014] Figure 3b According to some embodiments of the present invention Figure 3a Schematic diagram of a longitudinal section of the piston but in a closed position relative to the first busbar, the second busbar and the third busbar.

[0015] Figure 4 is a schematic diagram of a longitudinal section of an arc extinguishing device showing a first piston and a second piston arranged in an open position relative to a first busbar, a second busbar, a third busbar and also relative to a protective earth busbar according to some other embodiments of the present invention.

[0016] Figure 5a is a schematic top view of a piston of an arc extinguishing device arranged in a closed position relative to first, second, and third busbars according to some embodiments of the present invention.

[0017] Figure 5b is an arc extinguishing device according to some embodiments of the present invention Figure 5a Schematic side view of the piston in the embodiment of the present invention but in an open position relative to the first busbar, the second busbar and the third busbar (wherein the first busbar is hidden behind the piston).

[0018] Figure 5c The piston of the arc extinguishing device in the open position relative to the first busbar, the second busbar, the third busbar and the protective earth busbar according to some embodiments of the present invention (with Figure 5b Similar) schematic side view.

[0019] Figure 6a is a schematic top view of three pistons of an arc extinguishing device mechanically and electrically connected to each other and arranged relative to a first busbar, a second busbar, and a third busbar according to some embodiments of the present invention.

[0020] Figure 6b are mechanically and electrically connected to each other according to some embodiments of the present invention (similar to Figure 6a ) and a schematic top view of the three pistons of the arc extinguishing device arranged relative to the first busbar, the second busbar and the third busbar and also relative to the protective earth busbar. DETAILED DESCRIPTION

[0021] Now, the embodiments will be described more fully below with reference to the accompanying drawings, in which certain embodiments are shown. However, within the scope of the present disclosure, many different forms of other embodiments are also possible. Instead, the following embodiments are provided by way of example so that the present disclosure will be detailed and complete and will fully convey the scope of the present disclosure to those skilled in the art. Throughout the specification, the same reference numerals refer to the same elements.

[0022] Figure 1 A three-phase electrical switchgear 10 is illustrated, comprising a circuit breaker 11, e.g., a fault-clearing circuit breaker, arranged to disconnect current in each of three phases / lines L1, L2, and L3. The switchgear 10 may, for example, be arranged to disconnect current to a load, in which case the switchgear may be arranged between a power distribution system at the line side of the switchgear and at least one load at the load side of the switchgear. The switchgear may be arranged for low voltage applications or medium voltage applications, meaning that the alternating current (AC) phase-to-phase voltage of the phases L1, L2, and L3 is within the medium voltage range or the low voltage range, e.g., within the range 0.1 kV to 50 kV, or within the low voltage range 0.1 kV to 1 kV.

[0023] The circuit breaker 11 is typically capable of clearing the arc fault, i.e., disconnecting the current in phases L1, L2, and L3, within a time range of 30 ms to 60 ms after the arc fault is detected. This may be too slow to avoid damage caused by the arc fault. In order to quench the arc faster, the arc extinguishing device 1 is arranged in the switchgear 10 and is capable of short-circuiting all phases L1, L2, and L3 faster after the arc is detected, for example, within a time range of 0.1 ms to 5 ms, preferably within a time range of 0.1 ms to 2 ms. The arc extinguishing device 1 is connected to each of the phases L1, L2, and L3 of the switchgear via an electrical conductor. Specifically, the device 1 includes a phase busbar 5 (also referred to herein as a busbar) electrically connected to the phase line of the switchgear 10. In the example given herein, the three busbars 5 connected to the phases L1, L2, or L3, respectively, are represented as a first busbar T, a second busbar S, and a third busbar R, respectively. The arc extinguishing device 1 is configured to quench an arc by short-circuiting all three busbars T, S and R to each other (and optionally also to ground), thereby short-circuiting the three phases L1 , L2 and L3 to each other.

[0024] In order to detect an arc fault, the switchgear 10 includes an arc fault detector 13 connected to an arc fault sensor 12, such as an optical sensor, a current sensor, a pressure sensor and / or a thermal sensor, and configured to detect an arc in the switchgear, such as between two phases of the phases L1, L2 and L3, between a phase and ground, or generally within the switchgear 10. When the arc fault detector 13 detects an arc via the sensor 12, the detector 13 sends a start signal 14 to the arc extinguishing device 1, thereby causing at least one pyrotechnic actuator 3 (see Figure 2 )start up.

[0025] Figure 2 A piston P is shown arranged with a pyrotechnic actuator 3 , which piston P can be used in an arc extinguishing device 1 , for example in any of the embodiments illustrated in FIGS. 3 to 6 .

[0026] The piston P has a rear end 24 (eg, Figure 2 ), the front end 23 facing the axial movement direction, and the lateral surface 21. Figure 2 What has been said about the piston P shown is also valid for any other piston P of the device 1 .

[0027] The piston P (in particular, its lateral surface 21) is made of a conductive material, so that the piston is in electrical contact with the busbar 5 via the piston's lateral surface 21, enabling the piston to short-circuit the busbar 5 via the piston. The piston P generally has a circular cross-section. The piston is provided with a pyrotechnic actuator 3, which, when activated, generates an expanding gas that pushes the previously stationary piston P along its longitudinal axis 20 in a direction away from the actuator 3 (in the direction indicated by the axial arrow in the figure, below the piston).

[0028] The actuator 3 is arranged to pass through the opening 6 (e.g. Figure 4 、 Figure 5b and Figure 6a ) or a plurality of axially arranged openings 6 (e.g., as shown in FIG. Figure 5c and Figure 6b ) to move the piston P from its open position (e.g., as Figure 3a axially to its closed position (e.g., as shown) Figure 3b The opening 6 or each of the openings 6 may be a hole, a through hole or a blind hole in the busbar 5, or an opening between different busbars 5 that are electrically insulated from each other (e.g., busbars T, S and R in the following Figures 3 to 6).

[0029] In order to facilitate the axial movement of the piston P by the actuator 3 when activated, the housing 4 can be arranged around the piston P, preferably providing a sealed chamber 7 between the rear end 24 of the piston P and the interior of the housing 4 during the entire axial movement of the piston. Therefore, when the actuator 3 is activated, gas can be formed in the chamber 7, which pushes the rear end 24 of the piston P, thereby moving the piston axially and expanding the chamber 7.

[0030] Additionally or alternatively, the actuator itself may include a moving part that, when the pyrotechnic actuator is activated, presses axially against the piston P, making physical contact therewith, thereby causing the piston to move axially. In this case, the gas expansion may occur in a chamber within the actuator 3, rather than in the chamber 7 between the actuator 3 and the rear end 24 of the piston P.

[0031] Preferably, the piston P has a tapered shape, for example, tapering toward the front end 23 of the piston at an angle θ in the range of 3° to 12°, preferably 4° to 8°, for example 5.5° to 6.5°, relative to the longitudinal axis 20. This allows the piston P to wedge into one or more openings 6, the size and shape of which, in the closed position at the end of its axial movement, generally correspond to the piston's tapered shape, thereby improving the electrical connection between the piston P and the busbar 5. Preferably, the piston has a conical shape, for example, a truncated or frustoconical shape as shown in the figures. A conical piston typically has a circular base, forming the end surface of the rear end 24 of the piston. Typically, the cone is a perfect circle. In a truncated or untruncated perfect circular conical piston P, the angle θ between the generatrix of the lateral surface 21 and the central longitudinal axis 20 can therefore be in the range of 3° to 12°, preferably 4° to 8°, for example 5.5° to 6.5°.

[0032] Preferably, the inner surface of the one or more openings 6 is arranged to fit against the tapered shape of the piston P to improve the electrical connection. If the opening 6 is a hole in the busbar 5, the hole can be tapered at the same angle θ to the longitudinal axis 20 as the piston P, so as to fit against the lateral surface 21 at the end of the axial movement of the piston (corresponding to the closed position of the piston P and the closed state of the device 1). Additionally or alternatively, the shape (generally circular) and size (in a plane perpendicular to the longitudinal axis 20) of the hole 6 correspond to the cross-section of the piston, so that when the piston has reached its closed position, the inner surface of the hole contacts the lateral surface 21 of the piston around its entire circumference.

[0033] Likewise, if the opening 6 is located between two or more busbars 5, each corresponding end surface 22 of the busbars (see e.g. Figure 4 or Figure 5b ) can be inclined at the same angle θ to the axis 20 as the piston P, so as to fit against the lateral surface 21 at the end of the axial movement of the piston (corresponding to the closed position of the piston P and the closed state of the device 1). Additionally or alternatively, each respective end surface 22 of the generatrix 5 (see e.g. Figure 5a ) may be curved in a plane perpendicular to the longitudinal axis 20 so as to be in continuous contact around a section of the circumference of the piston when the piston has reached its closed position.

[0034] In order to guide the piston P into and / or through the opening 6 or a plurality of axially arranged openings 6, the piston may be provided with a guide 8 extending axially from the front end 23 of the piston (see also Figure 3a and Figure 3b The guide member 8 is made of an electrically insulating material and is generally cylindrical, for example, with a circular cross section.

[0035] The arc extinguishing device 1 includes at least one piston P. In some embodiments, for example, as illustrated in FIG3 and FIG5 , the at least one piston P consists of only one piston. In some other embodiments, for example, as Figure 4 As illustrated in FIG. 6 (with two pistons P1 and P2 ) and FIG. 6 (with three pistons P1 , P2 and P3 ), the at least one piston P is composed of a plurality of pistons, for example, two or three pistons.

[0036] Regardless of the number of pistons P in the arc extinguishing device 1, only one pyrotechnic actuator 3 is used in the device 1 for axially moving all at least one piston. In order to facilitate the movement of multiple pistons P by a single actuator 3 and to ensure that the pistons move simultaneously, all pistons can conveniently be rigidly mechanically connected to each other so that when the actuator 3 moves them axially, they do not move relative to each other. Therefore, the rigid mechanical connection 60 (see Figure 4 6 ) may be arranged between the pistons P so as to immobilize the pistons relative to each other even when the actuator 3 moves them axially together.

[0037] Additionally, since all three phases can be short-circuited by at least one piston P, when multiple pistons are used, the pistons are preferably connected, for example, by connections 60 made of a conductive material (see Figure 6a and Figure 6b ) are electrically connected to each other, thus also providing electrical connection between the pistons. Therefore, in some embodiments, all pistons P are electrically connected to each other so that after axial movement of the pistons, the first busbar T, the second busbar S, and the third busbar R are short-circuited to each other via the electrical connection 60.

[0038] When the arc extinguishing device 1 is open, each of the at least one piston P is in its open position in which all of the three busbars T, S and R are electrically insulated from one another at the one or more openings 6, for example by an electrically insulating gas (such as air) in the one or more openings 6 or by another electrically insulating gas / gas mixture (for example, (pure) nitrogen).

[0039] When the pyrotechnic actuator 3 is activated, all of the at least one piston P move axially simultaneously until they each reach their closed position, thereby closing the arc extinguishing device 1. In their closed position, all of the first busbars T, second busbars S and third busbars R are generally in physical contact (and therefore electrical contact) with at least one of the at least one piston P via their conductive lateral surfaces 21.

[0040] Figure 3a and Figure 3b The diagrams illustrate the open and closed positions of the piston P of the arc extinguishing device 1, respectively. In this example, the device 1 has only one piston P. Figure 3aIn the case of the piston P being in its open position and the device 1 being in the open state, Figure 3b In , the piston is in its closed position and the device 1 is in a closed state, wherein the lateral surface 21 of the piston P is in electrical contact with all three phases T, S and R, short-circuiting all phases to each other.

[0041] A single piston P is arranged to move axially through a respective axially aligned hole 6 of each of the three busbars T, S, and R forming the three busbar layers. It follows that, in its closed position, the piston P is in physical contact (electrical contact) with each of the first busbar T, the second busbar S, and the third busbar R. Specifically, the lateral surface 21 of the piston P is in physical contact with the interior surface of the hole 6 through the first busbar T, the inside surface of the hole 6 through the second busbar S, and the inside surface of the hole 6 through the third busbar R.

[0042] Therefore, in some embodiments of the present invention, the device 1 is arranged so that after axial movement of the piston P, the lateral surface 21 of the piston contacts the corresponding inner surfaces of the hole 6 in the first busbar T, the hole 6 in the second busbar S and the hole 6 in the third busbar R.

[0043] As reference Figure 2 As mentioned, the piston P can be provided with a guide 8 made of an electrically insulating material to facilitate its passage through the opening 6. This is particularly advantageous if the piston is arranged to electrically contact more than two axially aligned busbars of the opening 6, as shown in FIG3 . The guide 8 can then ensure that the piston is in physical and electrical contact with all the busbars it is arranged to contact simultaneously in its closed position. If the piston P contacts only two busbars, for example, T and S in FIG3 , there is a risk that the piston will be delayed or prevented from contacting all the busbars it is arranged to contact in its closed position, for example, by welding the two busbars that are first in contact.

[0044] To ensure controlled, straight axial movement of the piston P when the actuator 3 axially moves the piston P, the piston's guide 8 can be arranged to pass through a guide hole 51 in an insulator 50 made of an electrically insulating material, which is arranged on the other side of the opening 6 as seen in the direction of the piston's axial movement. For example, when the piston is in its open position, the front end of the guide 8 can extend into the guide hole 51 of the insulator 50 and can then further pass into or through the guide hole during axial movement until the piston reaches its closed position. Thus, the piston can be prevented from moving at an angle to the longitudinal axis or from tipping over during its axial movement.

[0045] Optionally, a protective earth (PE) busbar can be added as a fourth busbar layer. Similarly, the PE busbar can have a through hole 6 that is axially aligned with the holes 6 of the phase busbars T, S, and R, so that when the piston P is in its closed position, the lateral surface 21 of the piston P also makes electrical contact with the inner surface of the hole 6 of the PE busbar. The PE busbar may or may not be used in any of the embodiments of the apparatus 1, depending on whether it is desired to also short-circuit phases L1, L2, and L3 to ground.

[0046] Therefore, in some embodiments of the present invention, the arc extinguishing device 1 may further include a protective earthing busbar PE, which is arranged so that when the pyrotechnic actuator 3 is activated, each piston of the at least one piston P is axially moved until each piston of the at least one piston contacts the protective earthing busbar, so that each busbar of the first busbar T, the second busbar S and the third busbar R is also short-circuited to the protective earthing busbar via the at least one piston.

[0047] Figure 4 An example of an embodiment is shown in the figure, in which the at least one piston includes two pistons, namely, a first piston P1 and a second piston P2, and an actuator 3 is used to enable axial movement of the two pistons P1 and P2. The first piston P1 and the second piston P2 are rigidly mechanically connected to each other and are arranged to be driven by a single actuator 3 to move axially (in the figure, upward) together to contact the first busbar T, the second busbar S, and the third busbar R via their end surfaces 22, optionally through the first and second through-holes 6 of the PE busbar. The end surfaces 22 and the through-holes 6 can be as described herein.

[0048] Figure 5a An embodiment seen from above is illustrated in which a single piston P is able to short-circuit all three phases via the respective end surfaces 22 of the busbars T, S and R. The tapered shape of the piston P brings its lateral surface 21 into contact with the end surface 22 of the stationary busbar by means of its axial movement.

[0049] Figure 5b Shown with Figure 5a The same embodiment but seen from the side with the first generatrix T hidden behind the piston P.

[0050] Figure 5c The diagram shows Figure 5a and Figure 5bThe embodiment is similar to that of the embodiment but also has a PE busbar. The PE busbar can be arranged as a second busbar layer, wherein the holes 6 in the PE busbar are axially aligned with the openings 6 formed between the end surfaces 22 of the phase busbars T, S and R. Alternatively, the PE busbar can be arranged in the same plane as the phase busbars, wherein the end surface 22 of the PE busbar at the opening 6 is formed between the end surfaces 22 of the phase busbars, so that the end surface 22 of the PE busbar is also in electrical contact with the lateral surface 21 of the piston P in its closed position.

[0051] Therefore, in some embodiments of the present invention, the device 1 is arranged so that after axial movement of the piston P, the lateral surface 21 of the piston contacts the corresponding end surfaces 22 of the first busbar T, the second busbar S and the third busbar R, and optionally, contacts the corresponding end surface 22 of the PE busbar.

[0052] Figure 6a and Figure 6b An embodiment is shown in which the at least one piston P is composed of three pistons (a first piston P1 , a second piston P2 , and a third piston P3 ), one piston for each phase.

[0053] Figure 6a An embodiment without PE busbars is illustrated, wherein when the pistons are in their closed position, each of the three pistons is arranged to contact only a respective one of the three-phase busbars T, S and R, for example via through holes or blind holes 6 in the busbars. These phases are then short-circuited to each other via electrical connections 60 between the pistons.

[0054] Figure 6b The diagram shows Figure 6a An embodiment which is similar but also has a PE busbar. In the embodiment of the figure, the PE busbar is arranged as a separate layer and has a corresponding through hole 6 for each of the three pistons P1, P2 and P3. For each piston, its through hole in the PE busbar is axially aligned with the through hole or blind hole 6 in the phase busbar with which it is arranged to contact. Therefore, when the pistons are in their closed position, each piston is in electrical contact with the corresponding phase busbar and the PE busbar. Alternatively, only one or two of the three pistons can be arranged to be in electrical contact with the PE busbar when in its closed position. All phases are then still short-circuited to ground via the electrical connection 60 between the pistons, but may also not be short-circuited.

[0055] The invention has been described above mainly with reference to a few embodiments. However, it will be appreciated by those skilled in the art that other embodiments than those disclosed above are equally possible within the scope of the present disclosure as defined by the appended claims.

Claims

1. An arc extinguishing device (1) for a three-phase electrical switching device (10), the device comprising: a first busbar (T), a second busbar (S), and a third busbar (R), each for a corresponding phase (L2, L3, L1) of the three-phase electrical switching device; at least one piston (P) made of a conductive material and having a tapered shape tapering toward its front end (23); as well as only one pyrotechnic actuator (3) arranged to, when the pyrotechnic actuator is activated, axially move each of the at least one piston (P) until the first busbar (T), the second busbar (S) and the third busbar (R) are all short-circuited to each other via the at least one piston; Characterized in that the device (1) further comprises a protective earth busbar (PE), which is arranged so that when the pyrotechnic actuator (3) is activated, each of the at least one piston (P) is moved axially until each of the at least one piston contacts the protective earth busbar, so that each of the first busbar (T), the second busbar (S) and the third busbar (R) is also short-circuited to the protective earth busbar via the at least one piston.

2. Apparatus according to claim 1, wherein said at least one piston (P) consists of only one piston.

3. An apparatus according to claim 2, wherein the apparatus (1) is arranged so that after the axial movement of the piston (P), the lateral surface (21) of the piston contacts the corresponding inner surfaces of the hole (6) in the first busbar (T), the hole (6) in the second busbar (S) and the hole (6) in the third busbar (R).

4. An apparatus according to claim 2, wherein the apparatus (1) is arranged so that after the axial movement of the piston (P), the lateral surface (21) of the piston contacts the corresponding end surfaces (22) of the first busbar (T), the second busbar (S) and the third busbar (R).

5. The apparatus according to claim 4, wherein each of the end surfaces (22) of the first busbar (T), the second busbar (S) and the third busbar (R) is bent to fit against the lateral surface (21) of the piston (P), and the lateral surface (21) of the piston (P) is arranged to contact the end surface (22).

6. An apparatus according to claim 1, wherein the at least one piston (P) comprises a plurality of pistons (P1, P2, P3), all of which are rigidly mechanically connected to each other so that when the plurality of pistons (P1, P2, P3) are axially moved by the actuator (3), the plurality of pistons (P1, P2, P3) do not move relative to each other.

7. An apparatus according to claim 6, wherein all pistons (P) are electrically connected to each other so that after the axial movement of the pistons, the first busbar (T), the second busbar (S) and the third busbar (R) are short-circuited to each other through the electrical connection (60).

8. The apparatus of any preceding claim, wherein the tapered shape is a conical shape.

9. Apparatus according to any one of the preceding claims 1 to 7, wherein each of said at least one piston (P) is provided with a guide (8) made of electrically insulating material, said guide (8) extending axially from said front end (23) of said piston.

10. Apparatus according to any one of the preceding claims 1 to 7, wherein the tapered shape tapers at an angle (θ) in the range of 3° to 12° to the longitudinal axis (20) of the at least one piston.

11. The apparatus of claim 8, wherein the tapered shape is a frusto-conical shape.

12. The apparatus of claim 10, wherein the tapered shape tapers at an angle (θ) in the range of 4° to 8° to the longitudinal axis (20) of the at least one piston.

13. Apparatus according to claim 12, wherein the tapered shape tapers at an angle (θ) in the range of 5.5° to 6.5° to the longitudinal axis (20) of the at least one piston.

14. A three-phase electrical switching device (10) comprising a device (1) according to any one of the preceding claims and a fault-clearing circuit breaker (11), the fault-clearing circuit breaker (11) being arranged to disconnect the current of each of the three phases (L1, L2, L3), the three phases (L1, L2, L3) being connected to the first busbar (T), the second busbar (S) and the third busbar (R), respectively.

15. The switchgear according to claim 14, arranged for use in low voltage applications or medium voltage applications.

16. A switchgear according to claim 15, arranged for use in low voltage applications.

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