EP2814049A1

EP2814049A1 - Drive mechanism for a switching device

Info

Publication number: EP2814049A1
Application number: EP13171532.8A
Authority: EP
Inventors: Emmanouil Panousis; Bernhard Petermeier; Angelos Garyfallos; Markus Bujotzek
Original assignee: ABB Technology AG
Current assignee: ABB Schweiz AG
Priority date: 2013-06-11
Filing date: 2013-06-11
Publication date: 2014-12-17

Abstract

A drive mechanism (10) for a switching device (50), a switching device (50) comprising the drive mechanism (10), a use of the drive mechanism (10) for operating a switching device (50), a method for operating the drive mechanism (10) for a switching device (50) and a method for operating a switching device (50) by operating the drive mechanism (10) are described. The drive mechanism (10) comprises an arcing chamber (11) having a first end and a second end, wherein a first arcing element (12) and a second arcing element (13) are arranged in the arcing chamber (11). The first arcing element (12) is movable along a longitudinal axis (30) of the arcing chamber (11). The first arcing element (12) and the second arcing element (13) have mutually opposing surfaces configured for carrying an arc therebetween, the arc causing the first arcing element (12) to move along the longitudinal axis (30) away from the second arcing element (13) and towards the first end of the arcing chamber (11).

Description

TECHNICAL FIELD

Embodiments of the present disclosure relate to a drive mechanism for a switching device, in particular for a circuit breaker. Further, embodiments of the present disclosure relate to a switching device comprising a drive mechanism described herein. Additionally, a use of the drive mechanism for operating a switching device, and methods for operating a drive mechanism and for operating a switching device by operating the drive mechanism are described herein.

TECHNICAL BACKGROUND

Switches having a short response time are needed for many applications, e.g. circuit breakers, interrupters or disconnectors for low, medium and high voltage. Typically such switches are driven by a drive mechanism for separating contact elements. Conventional drive mechanisms for switches are spring drives, electromagnetic drives, motor drives, and pneumatic or hydraulic drives. However, conventional drive mechanisms are difficult to adapt for ultra-fast applications in which short switching times are desired, e.g. for fault-current interruption by a circuit breaker.
Hence there is a need for a drive mechanism for switches with which the required short switching times can be achieved. Particularly, a drive mechanism is needed with which actuation of heavy-weight contact elements at distances of several cm within short periods of time can be realized, typically within less than 10 ms from a tripping command or signal.
In view of the above, it is an object of the present disclosure to provide a drive mechanism for a switching device that overcomes at least some of the problems in the art. This object is achieved at least to some extent by a drive mechanism for a switching device, a switching device comprising drive mechanism described herein, a use of a drive mechanism as described herein for operating a switching device, a method for operating a drive mechanism for a switching device and a method for operating a switching device by operating a drive mechanism described herein according to the independent claims. Further aspects, advantages, and features of the present disclosure are apparent from the dependent claims, any claim combinations, the description, and the accompanying drawings.

SUMMARY OF THE DISCLOSURE

In view of the above, a drive mechanism for a switching device, in particular for a circuit breaker, is provided, wherein the drive mechanism comprises an insulating tube delimiting an arcing chamber having a first end and a second end, wherein a first arcing element and a second arcing element are arranged in the arcing chamber. The first arcing element is movable along a longitudinal axis of the arcing chamber. Further, the first arcing element and the second arcing element have mutually opposing surfaces configured for carrying an arc therebetween, an arc-generated pressure causing the first arcing element to move along the longitudinal axis away from the second arcing element and towards the first end of the arcing chamber.
According to a further aspect of the present disclosure, a switching device comprising a drive mechanism described herein is provided. The switching device further comprises two contact elements for closing and opening the switch. The first arcing element is coupled to at least one of the two contact elements for driving the at least one of the two contact elements such that the two contact elements connect or disconnect.
According to another aspect of the present disclosure, a use of a drive mechanism as described herein for operating a switching device is described.
According to another aspect of the present disclosure a method for operating a drive mechanism for a switching device, in particular for a circuit breaker, is provided, wherein the method comprises: inducing an arc between a first arcing element and a second arcing element; generating a pressure between mutually opposing surfaces of the first arcing element and the second arcing element by the arc; and causing the first arcing element to move along the longitudinal axis towards the first end of the arcing chamber due to the pressure, and optionally causing the second arcing element to move along the longitudinal axis towards the second end of the arcing chamber due to the pressure.
According to yet another aspect of the present disclosure a method for operating a switching device is provided, wherein the method comprises operating the drive mechanism as disclosed herein and at least one of closing or opening the switching device by driving at least one of the two contact elements of the switching device by at least one of the first arcing element and the second arcing element of the drive mechanism.
Further aspects, advantages, and features of the present disclosure are apparent from the dependent claims, any claim combinations, the description, and the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

In order to understand better the manner in which the above recited features of the present disclosure can be implemented, the general description briefly summarized above is complemented by a more specific disclosure which makes reference to purely exemplary embodiments. Such embodiments are depicted in the drawings and are detailed in the description which follows. In the drawings:

Figs. 1 and 2 show a drive mechanism in a cross-sectional view along its longitudinal axis according to embodiments described herein;
Fig. 3 shows a drive mechanism in a perspective view according to embodiments described herein;
Fig. 4 shows a switching device comprising a drive mechanism in a cross-sectional view according to embodiments described herein, with the switching device being in a closed state;
Fig. 5 shows of a switching device comprising a drive mechanism in a cross-sectional view according to embodiments described herein, with the switching device being in an open state;
Fig. 6 shows a flow chart for an embodiment of a method for operating a drive mechanism described herein for a switching device; and
Fig. 7 shows a flow chart for an embodiment of a method for operating a switching device described herein.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference will now be made in detail to the various embodiments, one or more examples of which are illustrated in each figure. Each example is provided by way of explanation and is not meant as a limitation. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with any other embodiment to yield yet a further embodiment. It is intended that the present disclosure includes such modifications and variations.
Within the following description of the drawings, the same reference numbers refer to the same or to similar components. Generally, only the differences with respect to the individual embodiments are described. Unless specified otherwise, the description of a part or aspect in one embodiment applies to a corresponding part or aspect in another embodiment, as well.
Before explaining exemplary embodiments illustrated in the figures, general aspects of the disclosed drive mechanism for a switching device are described.
According to embodiments of the drive mechanism described herein, the drive mechanism is used for a switching device, in particular for a circuit breaker. The drive mechanism comprises an insulating tube delimiting an arcing chamber which has a first end and a second end. In the arcing chamber a first arcing element and a second arcing element are arranged, and the first arcing element is movable along a longitudinal axis of the arcing chamber. The first arcing element and the second arcing element have mutually opposing surfaces configured for carrying an arc therebetween. The arc causes the first arcing element to move along the longitudinal axis away from the second arcing element and towards the first end of the arcing chamber.
In the present disclosure the term "arcing element" is to be understood as a substantially conductive element which is adapted for carrying an arc, more specifically is adapted for carrying the arc's foot. Hence, materials of the arc-carrying surface of the arcing element are arc-resistant, such as copper tungsten (CuW). Typically, the arc is an ablation-controlled arc. In the drive mechanism, the arc extends between mutually opposing surfaces of the two arcing elements. Herein, "mutually opposing" is defined as facing each other in such a manner that an arc is sustained between the arcing elements, at least in some positions of the arcing elements. According to embodiments, the mutually opposing surfaces may be essentially flat and/or may extend along a plane perpendicular to the axis. According to embodiments, the mutually opposing surfaces may comprise topological features such as peaks for enhancing arc formation.
The arc ignited between the opposing surfaces of the first and the second arcing elements is used for generating electrothermal propulsion. In detail, the electrothermal propulsion causing the first arcing element to move is based on a pressure generation between opposing surfaces of the first arcing element and the second arcing element due to a sudden gas expansion by heating of the gas therebetween. Particularly, the arc may carry an arcing current of 5 kA to 30 kA in amplitude and/or for a duration of at least 0.1 ms or at least 1 ms and/or at most 10 ms. The arc is extinguished when the electrical source no longer provides sufficient current and/or voltage.
Thus, according to embodiments, a drive mechanism based on the principle of electrothermal propulsion is provided. In particular, by employing the principle of electrothermal propulsion in the drive mechanism according to embodiments described herein, a drive mechanism is provided which is suitable for high-speed switching applications with fast actuation (i.e. opening or closing or in other words disconnecting or connecting) of switching contact elements. In embodiments of high-speed switching applications, the drive mechanism is capable of actuating switching contact elements at distances of several cm within very short periods of less than 10 ms. Thereby, high accelerations of the switching contact elements are achieved. In the present disclosure the term "contact elements" is to be understood as the elements of a switch which contact each other for establishing an electrical connection when the switch is closed, and which are separated from each other for interrupting or disconnecting the electrical connection when the switch is opened. Hence, at least one and possibly both of the contact elements is or are movable. According to an aspect, the drive mechanism is used for a circuit breaker, in particular for a medium voltage or (especially) a high voltage circuit breaker used for example in AC and DC applications.
According to embodiments, the insulating tube delimiting the arcing chamber comprises a non-conducting material, such as non-conducting plastic material, PTFE, a ceramic, a resin or composite material, possibly fiber reinforced. In the present disclosure the term "insulating tube" is to be understood as a substantially non-conducting tube. Particularly an insulating tube as described herein is made of a material having substantially no electrical conductivity. The insulating tube may be coated or may be attached to conducting material such as a metal sheet or high strength steel rods.
According to embodiments, the first arcing element is configured as a piston comprising a piston head and a piston shaft. Typically, the piston head essentially (i.e by at least 80%, particularly by at least 90%, more particularly by at least 99%) fills the entire lateral (i.e. orthogonal to the axis) cross-sectional area of the arcing chamber. Thereby, the piston head presents an efficient surface to be pushed by the pressurized gas in the arcing chamber. According to particular embodiments, the piston head may even be in contact with the inner surface of the arcing chamber and/or even form an essentially gas-tight contact with the inner surface of the arcing chamber. Typically, the piston head forms contact with the inner surface of the arcing chamber, which is configured for guiding a movement of the first arcing element towards the first end of the arcing chamber along the longitudinal axis. Typically, the interfacial surfaces of the piston head and the arcing chamber have low surface roughness such that the piston head can slide along the inner surface of the arcing chamber.
Furthermore, the first arcing element, in particular the piston shaft, can be slidingly mounted for guiding a sliding movement of the first arcing element towards the first end of the arcing chamber along the longitudinal axis. For this purpose, interfacial sliding surfaces between the enclosure of the arcing chamber (e.g. the first end of the arcing chamber) and the first arcing element, particularly its piston shaft, have low surface roughness as may be present in friction bearings. In particular, the first arcing element, in particular the piston shaft, may be supported by a sliding bearing. Thereby according to embodiments, the arc energy can substantially be converted into kinetic energy of the first arcing element with substantially no friction loss. In alternative embodiments, the first and/or second arcing element(s) may also have a different shape and configuration. For example, the first and/or second arcing element(s) may be configured without piston heads, but instead e.g. as cylindrical rods.
According to embodiments of the drive mechanism described herein, a first sliding contact is arranged at the first end of the arcing chamber. In the present disclosure the term "sliding contact" is to be understood as a contact with which an electrical contact can be established with a movable element, such as an arcing element as described herein. The first sliding contact is configured for transmitting an electrical current to the first arcing element. Particularly, the first sliding contact may be configured for transmitting an arcing current, e.g. at least one electrical current pulse of 5 kA up to 30 kA in amplitude and of durations ranging from 0.1 ms to 10 ms, to the first arcing element during a total application time period ranging from 0.1 ms to 10 ms.
Funhermore, the first sliding contact can be configured for guiding a movement of the first arcing element towards the first end of the arcing chamber along the longitudinal axis. The first sliding contact may have properties of the sliding mount described herein, and/or may be integrated in the sliding mount. Thus, for example, the interfacial sliding surfaces of the sliding contact and the portion of the first arcing element have low surface roughness as is useful for friction bearings.
According to embodiments, the sliding contact for transmitting an electrical current to the first arcing element comprises multiple contact fingers for establishing an electrical contact with the arcing element, e.g. its piston shaft. The sliding contact may be silver-plated.
According to embodiments of the drive mechanism described herein, the drive mechanism is provided with exhaust holes for relieving pressure from the inside of the arcing chamber, especially after the first arcing element has reached its desired displacement. For this purpose the exhaust holes can for example be provided at the first end of the arcing chamber and can provide a passage to an outside of the arcing chamber. Particularly, the exhaust holes are arranged in a first end cap provided at the first end of the arcing chamber. Preferably, the exhaust holes extend in an inclined direction with respect to the longitudinal axis of the arcing chamber. In embodiments, the exhaust holes are dimensioned to ensure that as soon as the first arcing element reaches its desired position, the remaining arc-generated pressure is released from the arcing chamber.
The exhaust holes may also be arranged for reducing a pressure buildup resulting from a compression of the gas volume between the first end of the arcing chamber and the first arcing element due to the movement of the first arcing element towards the first end of the arcing chamber (and optionally likewise with the second end and the second arcing element). This aspect is particularly useful, if the first and/or the second arcing element is shaped as a piston. In embodiments, the exhaust holes are dimensioned for quickly relieving the pressure as soon as the first arcing element reaches its desired displacement.
According to embodiments of the drive mechanism described herein, the first end of the arcing chamber comprises a first end cap and the second end of the arcing chamber comprises a second end cap. In embodiments, the first end cap and the second end cap can be fixedly connected with respective ends of the insulating tube, e.g. by clamp coupling, screw coupling or bolted fastening. According to embodiments, the first end cap and/or the second end cap are made of insulating material, e.g. non-conducting plastic material or some other material mentioned above for the insulating tube.
Typically, the first end cap and the second end cap are connected via tensile rods arranged outside of the arcing chamber or outside the insulating tube. The tensile rods preferably extend in the axial direction and are preferably used in order to fix the first end cap and the second end cap to each other and/or to axially fasten the drive mechanism.
According to embodiments the drive mechanism described herein further comprises a first damping element arranged and configured for damping a movement of the first arcing element. Particularly, the first damping element may be used for damping the movement of the first arcing element before, preferably just before, reaching the first end of the arcing chamber. Typically, the first damping element is positioned at a transition portion between the first end cap and the first end portion of the arcing chamber, preferably at a position at which the first arcing element has reached its desired displacement. Alternatively or additionally, the first damping element may be positioned outside the arcing chamber, e.g. coupled to the first arcing element's piston shaft. The first damping element may be an oil damping element or any other damping element useful in the art.
According to embodiments of the drive mechanism described herein, the first arcing element and the second arcing element are both movable along a longitudinal axis of the arcing chamber. The arc-generated pressure between the arcing elements causes them to move along the longitudinal axis away from each other. Thus, the arc causes the first arcing element to move towards the first end of the arcing chamber and the second arcing element to move towards the second end of the arcing chamber. Similarly as described above with respect to embodiments in which only the first arcing element is movable also in embodiments in which both arcing elements, i.e. the first arcing element and the second arcing element, are movable along a longitudinal axis of the arcing chamber the arc ignited between opposing surfaces of the first arcing element and the second arcing element is used for generating electrothermal propulsion.
In embodiments, the first arcing element and the second arcing element are equal in weight. Thereby according to embodiments, a drive mechanism is provided with which a recoil force acting on the drive mechanism can substantially be avoided, because in this case opposite momenta of equal magnitude are transferred to the first arcing element and the second arcing element.
According to embodiments of the drive mechanism described herein, the first arcing element and the second arcing element are configured symmetrically with respect to a plane oriented perpendicular to the longitudinal axis of the arcing chamber. Preferably, according to embodiments the entire drive mechanism (possibly but not necessarily even including the gears) is configured essentially symmetrically with respect to a plane being perpendicular to the longitudinal axis of the arcing chamber. According to a further embodiment, a drive mechanism with increased efficiency is provided, since the first arcing element and the second arcing element are accelerated into opposing directions due to the arc-generated pressure; furthermore both motions of the arcing element can be used for opening or closing contact elements of a switching device.
According to embodiments described herein in which the first arcing element and the second arcing element move, also referred to as "double motion" in the present disclosure, a drive mechanism can be provided in which substantially no recoil force acts on the drive mechanism during its operation.
Any feature described herein for the first arcing element is also applicable to the second arcing element, either together with the first arcing element or alone. In particular, the features, the arrangement and/or the configuration of the second arcing element may substantially correspond to the features, the arrangement and/or the configuration of the first arcing element, respectively, as described above. For example, the second arcing element may also be configured as a piston comprising a piston head and a piston shaft.
According to embodiments described herein, the drive mechanism further comprises a second sliding contact arranged at the second end of the arcing chamber. The second sliding contact is configured for transmitting an electrical current to the second arcing element. In embodiments, the features, the arrangement and the configuration of the second sliding contact substantially correspond to the features, the arrangement and the configuration of the first sliding contact described above, with the difference that the second sliding contact is associated with the second arcing element. Hence, the description of the first sliding contact also applies to the second sliding contact but in relation to the second arcing element instead of the first arcing element.
According to embodiments of the drive mechanism described herein, the drive mechanism is provided with exhaust holes for relieving pressure from the inside of the arcing chamber, after the second arcing element has reached its desired displacement. In embodiments, the exhaust holes are provided at the second end of the arcing chamber. Particularly, the exhaust holes are arranged in the second end cap provided at the second end of the arcing chamber. In embodiments, the features as well as the arrangement and/or configuration of the exhaust holes provided at the second end of the arcing chamber substantially correspond to the features, the arrangement and/or the configuration of the exhaust holes provided at the first end of the arcing chamber, respectively, as described above.
According to embodiments the drive mechanism described herein further can comprise a second damping element arranged and configured for damping a movement of the second arcing element. In embodiments, the features, the arrangement and/or the configuration of the second damping element substantially correspond to the features, the arrangement and/or the configuration of the first damping element, respectively, as described above.
Next, embodiments will be described in more detail with reference to the Figures.
As shown in Fig. 1, a drive mechanism 10 for a switching device 50, in particular for a circuit breaker, according to embodiments described herein comprises an insulating tube 14 delimiting an arcing chamber 11 having a first end and a second end. Preferably, the insulating tube 14 is surrounded by a metallic sleeve 15. A first arcing element 12 and a second arcing element 13 are arranged in the arcing chamber 11. According to exemplary embodiments as illustrated in Fig.1 the first arcing element 12 and/or the second arcing element 13 are movable along a longitudinal axis 30 of the arcing chamber 11. The first arcing element 12 and the second arcing element 13 have mutually opposing surfaces configured for carrying an arc therebetween. The arc is induced by applying an arcing voltage and/or arc current between the first arcing element 12 and the second arcing element 13 being in proximity to each other. The arc causes the first arcing element 12 to move towards the first end of the arcing chamber 11 along the longitudinal axis 30 and the second arcing element 13 to move towards the second end of the arcing chamber 11 along the longitudinal axis 30.
Thus, the arc ignited between the opposing surfaces of the first arcing element 12 and the second arcing element 13 is used for generating electrothermal propulsion. In detail, the electrothermal propulsion causing the first arcing element 12 and the second arcing element 13 to move is based on a pressure generation between opposing surfaces of the first arcing element 12 and the second arcing element 13 due to the arc-induced expansion of the gas therebetween.
As shown in Fig. 1, according to embodiments, the first arcing element 12 and the second arcing element 13 are configured as pistons each comprising a piston head 121, 131 and a piston shaft 122, 132. The piston heads 121, 131 present mutually opposing surfaces directed to each other for carrying the arc therebetween. These surfaces are almost filling the entire arc chamber cross-section, so that the pistons are efficiently pushed away from each other by the pressure generated due to the arc.
In embodiments, the piston heads 121, 131 are slidable along the inner surface of the arcing chamber 11. Preferably, the inner surface of the arcing chamber 11 is configured for guiding the movement of the first arcing element 12 towards the first end of the arcing chamber 11 along the longitudinal axis 30 as well as the movement of the second arcing element 13 towards the second end of the arcing chamber 11 along the longitudinal axis 30. In embodiments, the interfacial surfaces of the piston heads 121, 131 and the arcing chamber 11, particularly the inner surface of the insulating tube 14, have low surface roughnesses.
As shown in Fig. 1, according to embodiments of the drive mechanism 10, a first sliding contact 231 arranged at the first end of the arcing chamber 11 and a second sliding contact 232 arranged at the second end of the arcing chamber 11 are proved. Further, the first sliding contact 231 and the second sliding contact 232 are typically configured for guiding the movement of the first arcing element 12 and the second arcing element 13 along the longitudinal axis 30.
As illustrated in Fig. 1, according to typical embodiments, the first end of the arcing chamber 11 comprises a first end cap 21 and the second end of the arcing chamber 11 comprises a second end cap 22. Typically, the first and second end caps 21, 22 are fixedly connected to respective ends of the insulating tube 14.
Fig. 2 shows a cross-sectional view of an exemplary embodiment of the drive mechanism 10 which can be combined with other embodiments described herein. The description of Fig. 1 also applies to Fig. 2. As illustrated in Fig. 2 according to embodiments, the first end cap 21 and the second end cap 22 are connected to each other via tensile rods 41 arranged outside of the arcing chamber 11. The tensile rods 41 are typically used in order to fix the first end cap 21 and the second end cap 22 to each other. Preferably, the tensile rods 41 are employed to axially fasten the drive mechanism 10.
Next, the first and second sliding contacts 231, 232 shown in Fig. 2 and related items are described in more detail. According to embodiments of the drive mechanism 10, as exemplarily illustrated in Fig. 2, the first and second end caps 21, 22 are provided with electrical interface elements 25 for transmitting an electrical current to the first and second arcing elements 12, 13 via the first and second sliding contacts 231, 232. Typically, for inducing an arc between the opposing surfaces of the first and second arcing elements 12, 13 an electrical voltage is applied between the two electrical interface elements 25 (on the lefthand side and on the right-hand side). Correspondingly, the arc ignites and an arcing current flows from the electrical interface elements 25 associated with the first arcing element 12 over the sliding contact 231 to the first arcing element 12, then via the arc to the second arcing element 13, then via the sliding contact 232 to the electrical interface elements 25 associated with the second arcing element 13. Thereby, the arc and the electrothermal propulsion described above are initiated.
In Fig. 3 a perspective view of a drive mechanism according to an exemplary embodiment similar to that of Fig. 2 is shown. The description of Figs. 1 and 2 also applies to Fig. 3. As shown in Fig. 3, the first and second end caps 21, 22 can be provided with exhaust holes 40. The exhaust holes 40 extend from the inside of the arcing chamber (at or near a respective end thereof) to the outside of its enclosure. Typically, the exhaust holes 40 may be arranged in contact with or through the end caps 21, 22. As described above, the exhaust holes 40 are employed for relieving pressure inside the arcing chamber 11, which increases due to gas expansion inside the arcing chamber 11 as a result of the electrothermal propulsion.
Figs. 1-3 show a drive mechanism 10 with both arcing elements 12, 13 being movable. According to a variation, only the first arcing element 12 is movable, and the second arcing element 13 is fixed. In this case the second arcing element 13 can be fixed to the arcing chamber enclosure, and sliding contacts and the like are not necessary for the second arcing element 13.
Next, Figs. 4 and 5 will be described. These Figures illustrate the use of the drive mechanism 10 for operating a switching device 50, more particularly a high voltage circuit breaker 50.
Figs. 4 and 5 show the switching device 50 comprising the drive mechanism 10 described herein, and further comprising two contact elements 51, 52 for closing and opening the switching device 50. Fig. 4 shows a cross-sectional view of the switching device 50 in a closed state, and Fig. 5 shows a cross-sectional view of the switching device 50 in an open state.
As indicated by the arrow pointing towards the drive mechanism 10, the first contact element 51 of the switching device 50 is movable along a switching axis. A gear system G can couple the first arcing element 12 to the first contact element 51 of the switching device. As can be seen from the arrows depicted in Figs. 4 and 5 indicating the movements of the first arcing element 12 and the first contact element 51, the gear system G translates the movement of the first arcing element 12 caused by the arc into a movement of the first contact element 51 for opening the switching device 50.
Details of the gear G are not shown in Figs. 4 and 5. The gear G may be any gear used for coupling a driving mechanism, e.g. a spring drive, to a switching device such as a circuit breaker. The gear may, for example, by realized as a lever-type gear. According to an aspect shown in Figs. 4 and 5, the switch axis is parallel to the axis of the drive mechanism, and the gear G translates a motion of the first arcing element 12 into an opposite movement of the first contact element 51. While in principle any angle can be chosen between the switch axis and the axis of the drive mechanism, the parallel orientation allows for a particularly simple and effective transmission of motion by the gear G.
In Figs. 4 and 5, only the coupling between the first arcing element 12 and the first contact element 51 of the switching device 50 is shown. This may, for example, be all that is necessary for a single-motion switching device 50 in which only the first contact element 51 is movable, whereas the second contact element 52 is fixed. The first arcing element 12 may be used in any known manner for driving the switching device 50. For example, the switching device 50 is a double-motion switch or switching device 50, and both contact elements 51, 52 may be driven by the first arcing element 12 to move in opposite directions via any known gear (e.g. via a lever gear).
Other couplings (not shown) may be implemented, as well. For example, according to one embodiment, the switching device 50 is a double-motion switch, i.e. both contact elements 51, 52 are movable, and the first contact element 51 is coupled by a first gear to the first arcing element 12, and the second contact element 52 is coupled by a second gear to the second arcing element 13 (not shown). This embodiment allows a particularly advantageous reduction of recoil forces.
According to yet another embodiment, the first and second arcing elements 12, 13 are jointly coupled via a common gear such that motion of either arcing element 12 or 13 and/or of both arcing elements 12, 13 combined drives the switching device 50, in any known manner (e.g. any coupling of the first arcing element 12 to the switching device 50 described above may be used for the pair of arcing elements 12, 13 coupled by a gear using both motions in opposite directions. These embodiments allow a synchronized motion of both contact elements 51, 52 and/or of both arcing elements 12, 13.
Also, additional couplings or gears may couple to one or both arcing elements 12, 13 for moving additional parts of the switching device 50, e.g. nominal contacts.
In any of these embodiments, at least the first arcing element 12 is coupled to at least one of the two contact elements 51, 52. Thereby, by a movement of at least one of the arcing elements 12, 13 at least one of the two contact elements 51, 52 is driven such that an electrical contact between the two contact elements 51, 52 is established or interrupted. In embodiments, the switching time for closing or opening the switching device 50, i.e. for establishing or interrupting an electrical contact, is ranging from 1 ms to 10 ms from a tripping command or a tripping signal.
According to another aspect of the present disclosure, a method for operating a drive mechanism 10 for a switching device 50, in particular for a circuit breaker 50, is provided. According to embodiments, as exemplarily shown in Fig. 6, the method for operating a drive mechanism 10 comprises: inducing 101 an arc between a first arcing element 12 and a second arcing element 13; generating 102 a pressure between mutually opposing surfaces of the first arcing element 12 and the second arcing element 13 by the arc; and causing 103 the first arcing element 12 to move towards the first end of the arcing chamber 11 along the longitudinal axis 30 due to the pressure generated by the arc.
According to another aspect, the method further includes causing the second arcing element 13 to move towards the second end of the arcing chamber 11 along the longitudinal axis 30 due to the pressure generated by the arc, or alternatively by another arc. Any aspect described herein for the motion of the second arcing element 13 also applies to this method.
According to embodiments of the method for operating a drive mechanism 10 for a switching device 50, the step of inducing 101 the arc includes applying at least one current pulse of 5 kA to 30 kA in amplitude and durations of 0.1 ms to 10 ms, for a period of time from 0.1ms to 10 ms to the first arcing element 12 and/or to the second arcing element 13. In embodiments, applying the at least one current pulse includes delivering the at least one pulse from a pre-charged capacitor. In embodiments, the at least one current pulse is provided by a fault current, in particular by the fault current which shall be interrupted by the switching device 50 in case of a fault.
According to another aspect of the present disclosure, a method for operating a switching device 50 is provided. According to embodiments, as exemplarily shown in Fig. 7, the method for operating a switching device 50 comprises (i) operating 201 the drive mechanism 10 as disclosed herein and at least one of (ii) closing 202 or (iii) opening 203 the switching device 50 by driving 204 at least one of the two contact elements 51, 52 by at least one of the first arcing element 12 and the second arcing element 13.
Embodiments of the method for operating a switching device 50 include operating the switching device 50 via a gear system G coupled to at least one of the two contact elements 51, 52 and to at least the first arcing element 12 (and optionally also to the second arcing element 13) of the drive mechanism 10. For example, any of the couplings between arcing element(s) 12, 13 and contact element(s) 51, 52 described and/or illustrated in conjunction with Figs. 4 and 5 above may be realized.

Claims

A drive mechanism (10) for a switching device (50), in particular for a circuit breaker, wherein the drive mechanism (10) comprises an insulating tube (14) delimiting an arcing chamber (11) which has a first end and a second end, wherein a first arcing element (12) and a second arcing element (13) are arranged in the arcing chamber (11), the first arcing element (12) is movable along a longitudinal axis (30) of the arcing chamber (11), the first arcing element (12) and the second arcing element (13) have mutually opposing surfaces configured for carrying an arc therebetween, and wherein an arc-generated pressure causes the first arcing element (12) to move along the longitudinal axis (30) away from the second arcing element (13) and towards the first end of the arcing chamber (11).
The drive mechanism (10) according to claim 1, wherein the drive mechanism (10) comprises a first sliding contact (231) arranged at the first end of the arcing chamber (11), and the first sliding contact (231) is configured for transmitting an electrical current to the first arcing element (12).
The drive mechanism (10) according to any one of the preceding claims, wherein the arcing chamber (11) is provided with exhaust holes (40) for relieving a pressure inside the arcing chamber (11).
The drive mechanism (10) according to any one of the preceding claims, wherein the first end of the arcing chamber (11) comprises a first end cap (21) and the second end of the arcing chamber (11) comprises a second end cap (22), wherein further the first end cap (21) and the second end cap (22) are connected to one another via tensile rods (41) arranged outside of the arcing chamber (11).
The drive mechanism (10) according to any one of the preceding claims, further comprising at least one damping element being arranged and configured for damping a movement of the first arcing element (12).
The drive mechanism (10) according to any one of the preceding claims, wherein the first arcing element (12) and the second arcing element (13) are movable along the longitudinal axis (30), and the arc causing the first arcing element (12) and the second arcing element (13) to move along the longitudinal axis (30) away from each other towards the first and the second end of the arcing chamber (11), respectively.
The drive mechanism (10) according to any one of the preceding claims, wherein the first arcing element (12) and the second arcing element (13), preferably the drive mechanism (10), are or is configured symmetrically with respect to a plane which is perpendicular to the longitudinal axis (30); and/or wherein the mutually opposing surfaces of the first arcing element (12) and the second arcing element (13) comprise topological features, in particular peaks, for enhancing formation of the arc between the mutually opposing surfaces.
A switching device (50), comprising the drive mechanism (10) according to any one of the preceding claims, and further comprising two contact elements (51, 52) for closing and opening the switching device (50), wherein the first arcing element (12) is coupled to at least one of the two contact elements (51, 52) for driving the at least one of the two contact elements (51, 52) such that the two contact elements (51, 52) connect and/or disconnect.
The switching device (50) according to claim 8, wherein a switching time for closing or opening the switching device (50) is in a range from 1 ms to 10 ms.
A use of the drive mechanism (10) according to any one of the preceding claims 1 to 7, for operating a switching device (50).
A method for operating a drive mechanism (10) for a switching device (50), in particular for a circuit breaker, in particular for a drive mechanism (10) according to any one of the preceding claims 1 to 7, wherein the method comprises:
a) Inducing (101) an arc between a first arcing element (12) and a second arcing element (13);

b) Generating (102) a pressure between mutually opposing surfaces of the first arcing element (12) and the second arcing element (13) by the arc; and

c) Causing (103) the first arcing element (12) to move towards the first end of the arcing chamber (11) along the longitudinal axis (30) due to the pressure generated by the arc.
The method for operating a drive mechanism (10) for a switching device (50) according to claim 11, wherein inducing (101) the arc includes applying at least one current pulse of 5 kA to 30 kA in amplitude and of durations in a range from 0.1 ms to 10 ms to the first arcing element (12) and/or to the second arcing element (13), in particular applying the at least one current pulse during a total application time period ranging from 0.1ms to 10 ms.
The method for operating a drive mechanism (10) for a switching device (50) according to any one of the preceding claims 11-12, wherein applying a or the current pulse for inducing (101) the arc includes delivering the current pulse from a pre-charged capacitor, or providing the current pulse by a fault current through the switching device (50).
A method for operating a switching device (50), wherein the method comprises operating (201) a drive mechanism (10) according to any one of the claims 11 to 13, and at least one of a closing operation (202) and opening operation (203) of the switching device (50) by driving (204) at least one of the two contact elements (51, 52) of the switching device (50) by at least one of the first arcing element (12) and the second arcing element (13) of the drive mechanism (10).
The method for operating a switching device (50) according to claim 14, wherein the method includes operating the switching device (50) via a gear system (G), which is coupled to one of the two contact elements (51, 52) of the switching device (50) and to at least one of the first arcing element (12) and the second arcing element (13) of the drive mechanism (10).