AU2012288979B2

AU2012288979B2 - Switching device

Info

Publication number: AU2012288979B2
Application number: AU2012288979A
Authority: AU
Inventors: Manfred Meinherz; Clemens Ruthnick; Bernd Wolkerling
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2011-07-28
Filing date: 2012-07-20
Publication date: 2016-09-08
Anticipated expiration: 2032-07-20
Also published as: WO2013014070A1; DE102011079969A1; AU2012288979A1; EP2718950A1; EP2718950B1; CA2843031A1

Abstract

The invention relates to a switching device that comprises an interrupter path. The interrupter path is equipped with a first switching point (1) and a second switching point (2). The two switching points (1, 2) are actuated during a switch process in such a way that the first switching point (1) operates before the second switching point (2) during a switch-off process and after the second switching point (2) during a switch-on process. The first switching point (1) and the second switching point (2) are connected electrically in series by means of an axially movable contact pin (8b). A movable contact piece (11) rests on the movable contact pin (8b) in a sliding manner.

Description

Description Switching Device

The invention relates to a switching device having an interrupter path that comprises a first switching site and a second switching site having in each case contact pieces that can move relative to one another, wherein the first switching site is electrically connected in series to the second switching site by way of a contact pin that can be axially displaced and during a switching process the first switching site and the second switching site are actuated by force and during a switching-off process the first switching site operates before the second switching site and during a switching-on process said first switching site operates after the second switching site. A switching device of this type is known by way of example from the European patent application EP 0 070 794 A2. In this case, the switching device is equipped with a first switching site and a second switching site that are arranged lying axially one behind the other. The two switching sites are electrically connected in series to one another by way of a contact pin, wherein the contact pin can be axially displaced. A construction of this type comprises the disadvantage that, by virtue of the fact that the switching sites lie axially one behind the other, the structure of the switching device is comparatively long.

Furthermore, a so-called hybrid circuit breaker is known from the European patent application EP 1 109 187 Al, which hybrid circuit breaker likewise comprises two switching sites. An arrangement wherein the two switching sites lie one behind the other is also provided in this construction. In order to stagger with respect to time the points in time at which the switching sites are switched during a switching process, a gearing mechanism is arranged in this construction between the two switching sites. Additional installation space is necessary to accommodate the gearing mechanism and this additionally increases the axial extent of the switching device.

OBJECT OF THE INVENTION

It is an object of the present invention to substantially overcome or at least ameliorate one or more of the above disadvantages, or at least provide a useful alternative.

In a first aspect the present invention provides a switching device having an interrupter path that comprises a first switching site and a second switching site having in each case contact pieces movable relative to one another, wherein: the first switching site is electrically connected in series to the second switching site by way of an axially displaceable contact pin; and a movable contact piece is located on the axially displaceable contact pin in a sliding manner adapted to perform a switching process, wherein the first switching site and the second switching site are actuated by force; during a switching-off process the first switching site operates before the second switching site ; and during a switching-on process said first switching site operates after the second switching site.

The two switching sites are in each case delimited by contact pieces that may move relative to one another. The two switching sites are electrically connected in series, wherein a contact pin that may be displaced is used in order to provide the connection. The contact pin may be used as an individual element of an arrangement wherein the contact pieces of the two switching sites make direct contact with one another. However, it may also be provided that the contact pin is only embodied as a section of a conductor track that connects the two switching sites. An arrangement wherein a movable contact piece is located on the contact pin renders possible a deviation from the known arrangement of the switching paths being arranged axially one behind the other. The second switching site may by way of example also use a space that is located radially around the contact pin. An arrangement wherein the movable contact piece is located on the contact pin further renders it possible to move the moveable contact piece, which is located on said contact pin in a sliding manner, together with or independently of the contact pin, and thus renders it possible to influence in a simplified manner the staggering with respect to time of the points in time at which the two switching sites are switched. An arrangement wherein the movable contact piece is located on the contact pin that may be displaced further renders it possible to arrange the movable contact piece, which is located on said contact pin, in a radially spaced manner with respect to the contact pin, by way of example to arrange the contact piece in a radial extending manner about the contact pin, wherein the contact pin penetrates the radially extending contact piece. As a result, it is further possible by way of the contact pin to effect both a drive of the first switching site and also a drive of the second switching site. A movement may therefore be coupled to the movable contact pin by way of the one and the same drive device and a corresponding control of the first switching site and/or the second switching site may be achieved by way of the contact pin. However, in order to achieve a greater variability, the movements may also be controlled independently. For this purpose, the movements may be produced by way of example by different drives. However, it may also be provided that the same drive is used and different sequences of movement are coupled by way of corresponding gearing mechanisms on the one hand to the movable contact pin and on the other hand to the movable contact piece that is located in a sliding manner on the movable contact pin.

An interrupter arrangement having a first switching path and a second switching path renders it possible to embody differently constructed switching sites, wherein by virtue of the fact that the points in time at which the two switching sites are switched are staggered with respect to time, differing technical demands are placed in each case on the switching sites. It is thus by way of example possible during a switching-off process to allow an increased loading as a result of expected switching-off arcs at the switching site that opens first, in this case the first switching site, whereas the switching site that is subsequently switched is loaded to a lesser degree with respect to switching-off arcs that occur. The series connection renders it possible by way of example that during a switching-off process initially a switching-off arc burns in the first switching site and the second switching site is subsequently opened.

This staggered arrangement with respect to time may vary as required. Thus, on the one hand, it may be provided that the second switching site only opens if a switching-off arc in the first switching site is already reliably extinguished. Or, it may also be provided that the second switching site is then already opened if it is still to be expected that a switching-off arc is burning in the first switching site.

An additional preferred embodiment may provide that the contact pin is a part of a movable contact piece of the first switching site and the contact piece that is located on the movable contact pin is allocated to the second switching site.

By virtue of using the contact pin as a part of the movable contact piece of the first switching site and by virtue of the fact that the movable contact piece is located on the contact pin, it is rendered possible to provide a direct electrically conductive connection in order to produce a series connection between the two switching sites. The first switching site and also the second switching site may by way of example be connected to one another in an electrically conductive manner by way of a sliding contact arrangement. As a consequence, it is possible to connect the two switching sites to one another by way of a low impedance connecting current path. An arrangement wherein the movable contact piece is located directly on the contact pin further renders it possible to arrange the two contact sites spatially near to one another so that an axial spacing between said contact sites is reduced and a structurally short switching device is rendered possible. Where necessary, the switching sites overlap one another in the radial direction.

Furthermore, it may be provided that the first switching site is embodied as a vacuum interrupter. A vacuum interrupter comprises a switching site which is arranged within an enclosed space between the contact pieces that may move relative to one another. Dirt is therefore prevented from penetrating into the switching site. The enclosed space is evacuated. A vacuum comprises a high dielectric strength even over small distances. It is therefore possible to control a high switching capacity in the case of relatively small relative movements of the contact pieces of a switching site of a vacuum interrupter to one another.

By virtue of the fact that a vacuum interrupter is used for the first switching site, it is rendered possible to embody the second switching site in an alternative, cost-effective construction. By way of example, a flow-through having an electrically insulating gas or an electrically insulating fluid may be provided for the second switching site, wherein the electrically insulating fluid that penetrates the second switching site should also flow around the vacuum interrupter of the first switching site. The electrically insulating fluid may be arranged as required within an encapsulating housing that surrounds the switching sites, within which encapsulating housing the electrically insulating fluid is placed under an increased pressure. By way of example, insulating fluids, sulfur hexafluoride gas, nitrogen gas or other compressible electrically insulating gases are suitable as an electrically insulating fluid. A preferred embodiment may further provide that the contact pin is a contact stem of a movable contact piece of the vacuum interrupter. A vacuum interrupter comprises a switching site in its interior. The switching site is delimited by means of contact pieces that may move relative to one another. A movement at least of one of the contact pieces is to be transferred through a wall of the vacuum interrupter. It has been established as preferred to embody the movable contact pieces with a slim contact stem that penetrates the wall of the vacuum interrupter. A contact stem is embodied in an electrically conductive manner so that by way of said contact stem it is possible on the one hand to make electrical contact with the switching site. On the other hand, thermal energy may be discharged from the interior of the vacuum interrupter by way of the contact stem. If a contact stem of a vacuum interrupter is now used to support a movable contact piece of the second switching site, the construction of the vacuum interrupter may be used to mechanically stabilize the second switching site itself. Consequently, by way of example, guide and holding elements for the movable contact piece of the second switching site are omitted. The arrangement wherein the movable contact piece of the second switching site is located on the contact stem of the movable contact piece of the vacuum interrupter renders it possible to use guiding elements both for movable parts of the first switching site and of the second switching site. Consequently, it is possible to embody a structurally compact switching device that is structurally short in the axial direction as a result of the arrangement wherein the movable contact piece is located on the contact pin and on the other hand the complexity of the switching device is reduced by virtue of the fact that the switching sites have a common support and said switching sites are guided in a mechanical manner.

Preferred embodiments of the present invention will now be described, by way of examples only, with reference to the accompanying drawings:

Figure 1 illustrates a first switching site and a second switching site in each case in the opened state,

Figure 2 illustrates the first switching site in an intermediate state and the second switching site in the closed state and

Figure 3 illustrates the first switching site and the second switching site in each case in the closed state.

Hereinunder, the construction of a switching device in accordance with the invention is initially fundamentally described with reference to figure 1.

Figure 1 illustrates the switching device in a schematic illustration. The switching device comprises a first switching site 1 and also a second switching site 2. The first switching site 1 is a part of a vacuum interrupter. The vacuum interrupter is equipped with a fluid tight housing 3 that acts by way of example in an electrically insulating manner. The housing 3 is penetrated by contact pieces 4, 5 of the switching site 1, which contact pieces can move relative to one another. The first switching site 1 comprises a fixed contact piece 4 and also a movable contact piece 5. The two contact pieces 4, 5 of the first switching site 1 are arranged with their end faces facing one another.

The fixed contact piece 4 is connected to the housing 3 in a non-rotatable manner and penetrates this housing 3 in a fluid-tight manner. A first connection point 6 of the interrupter unit is arranged on the end of the fixed contact piece 4 of the first switching site 1, which end is located on the exterior of the housing 3. The movable contact piece 5 likewise penetrates the housing 3. It is provided that the housing 3 comprises a shape-changing section 7 so that a relative movement of the movable contact piece 5 of the first switching site 1 with respect to the fixed contact piece 4 of the switching site 1 is rendered possible. In the present invention, the shape-changing section 7 is embodied in the form of bellows that are penetrated in a fluid tight manner by the movable contact piece 5 of the first switching site 1. The two contact pieces 4, 5 of the first switching site 1 comprise radially widening sections on their ends that face one another, which radially extending sections delimit the switching site 1. The two contact pieces 4, 5 of the first switching site 1 are equipped in each case with contact stems 8a, 8b on the regions that are remote with respect to one another. The contact stems 8a, 8b in each case penetrate the housing 3. The first connection point 6 of the interrupter unit is arranged on the contact stem 8a of the fixed contact piece 4 of the first switching site 1. The two contact pieces 4, 5 can move along a longitudinal axis 9 relative to one another. The longitudinal axis 9 lies in each case in the longitudinal axis of the two contact stems 8a, 8b. The movable contact piece 5 of the first switching site 1 can be displaced with its contact stem 8b in an axial manner along the longitudinal axis 9. For this purpose, an insulating rod 10 is coupled to the end of the contact stem 8b of the movable contact piece 5, which end is remote from the first switching site 1. A movement in the direction of the longitudinal axis 9 can be transferred by way of the insulating rod 10 to the movable contact piece 5 of the first switching site 1 so that a relative movement between the two contact pieces 4, 5 of the first switching site 1 is rendered possible. The insulating rod 10 connects to the end of the contact stem 8b of the movable contact piece 5 of the first switching site 1, which end is remote from the first switching site 1. A movable contact piece 11 of the second switching site 2 is arranged on an end of the contact stem 8b of the movable contact piece 5 of the first switching site 1, which end lies outside the housing 3 of the vacuum interrupter. The movable contact piece 11 of the second switching site 2 comprises a sleeve 12 that encompasses the periphery of the contact stem 8b of the movable contact piece 5 of the first switching site 1. A sliding contact arrangement, by way of example reversibly deformable contact fingers or differently embodied spring elements, is arranged between the mutually facing regions of the sleeve 12 and/or of the contact stem 8b of the movable contact piece 5 of the first switching site 1. Alternatively, or as a complement thereto, a different electrical contact of the movable contact piece 11 of the second switching site 2 and also of the movable contact piece 5 of the first switching site 1 can be provided. Connected to the sleeve 12 in a nonrotatable manner, a support element of the movable contact piece 11 of the second switching site 2 extends, which support element protrudes radially from the main axis 9. By way of example, an annular circumferential contact surface 13 is arranged on the radially protruding carrying element. The annular contact surface 13 of the movable contact piece 11 of the second switching site 2 renders it possible for said movable contact piece to contact a mirror-imaged contact surface of a fixed contact piece 14 of the second switching site 2. A switching path of the second switching site 2 is arranged between the contact surfaces of the fixed contact piece 14 and/or of the movable contact piece 11 of the second switching site 2. The contact pieces 11, 14 of the second switching site 2 are essentially embodied in an annular manner and arranged coaxially with respect to the longitudinal axis 9, wherein the two contact pieces 11, 14 of the second switching site 2 are penetrated by the contact stem 8b of the movable contact piece of the first switching site 1. A second connection point 15 of the interrupter path of the switching device is connected to the fixed contact piece 14 of the second switching site 2 in an electrically conductive manner .

The interrupter path having the two switching sites 1, 2 that are electrically connected in series and arranged between the two connection points 6, 15 can be connected to an electrical network by way of the two connection points 6, 15. A current path between the two connection points 6, 15 can therefore be disconnected and/or produced by means of the interrupter path of the switching device.

The movable contact piece 11 of the second switching site 2 is pressed by way of example by means of a spring 18 against a stop 17 that is located on the contact stem 8b of the movable contact piece 5 of the first switching site 1. The action of force of the spring 18 is directed in such a manner that the movable contact piece 11 of the second switching site 2 is pressed against the stop 17 in the direction of the fixed contact piece 14 of the second switching site 2. As a consequence, it is possible in the case of a movement of the insulating rod 10 and also of the contact stem 8b of the movable contact piece 5 of the first switching site 1, which contact stem is coupled to said insulating rod, to transfer also a movement to the movable contact piece 11 of the second switching site 2. The position of the stop 17 is selected in such a manner that during a switching-on process, the contact pieces 11, 14 of the second switching site 2 initially make contact with one another. A sequence of a switching-on process is described hereinunder starting from the switched-off position of the first switching site 1 and also the second switching site 2 that are illustrated in figure 1. A movement in the direction of the longitudinal axis 9 is transferred to the contact stem 8b of the movable contact piece 5 of the first switching site 1 by means of the insulating rod 10 and consequently also to the sleeve 12 of the movable contact piece 11 of the second switching site 2. A movement during a switching-on process is provided in the direction of the arrow 16. A movement of the movable contact piece 11 of the second switching site 2 in the direction of the fixed contact piece 14 of the second switching site 2 is achieved corresponding to the movement of the insulating rod 10.

The movable contact piece 5 moves in parallel with respect to the contact stem 8b of the movable contact piece 5 of the first switching site 1 in the direction of the fixed contact piece 4 of the first switching site 1. The two contact pieces 11, 14 of the first switching site 1 initially make contact by virtue of the fact that the movable contact piece 11 of the second switching site 2 is arranged in an axially offset manner on the contact stem 8b. As a consequence, the contact pieces 11, 14 of the second switching site 2 initially make contact during a switching-on process. Although the contact pieces 4, 5 of the first switching site 1 have moved closer to one another, said contact pieces 4, 5 of the first switching site 1 have not yet made contact. After the contact pieces 11, 14 of the second switching site 2 have made contact with one another, the insulating rod 10 and/or the contact stem 8b continue to move against the force of the spring 18 (cf. fig. 2). The insulating rod 10 continues to move in the direction of the longitudinal axis 9 until the two contact pieces 4, 5 of the first switching site 1 make contact with one another. A switching-on movement of the interrupter path of the switching device is completed once the contact pieces 4, 5 of the first switching site 1 make contact with one another.

During a switching-off process, the insulating rod 10 together with the contact stem 8b that is fixed thereto moves in the reverse direction with respect to a switching-on movement. The contact pieces 4, 5 of the first switching site 1 initially separate as a result of the arrangement of the two switching sites 1, 2 and also of the respective fixed contact pieces 4, 14 and/or the movable contact pieces 5, 11 of the first switching site 1 and/or of the second switching site 2, whereas the movable contact piece 11 of the second switching site 2 remains pressed against the fixed contact piece 14 by means of the spring 18. As a consequence, where necessary switching-off arcs that occur are initially directed to the two contact pieces 4, 5 of the first switching site 1. As the procedure of removing the contact pieces 4, 5 of the first switching site 1 from one another continues and the sleeve 12 stops against the stop 17 the movable contact piece 11 of the second switching site 2 can now be removed from the fixed contact piece 14 of the second switching site 2.

The contact pieces 4, 5; 11, 14 of the first switching site 1 and/or of the second switching site 2 can now be moved completely into their switched-off positions. Following this, the interrupter unit is in turn ready to be moved from its switched-off position, as is illustrated in figure 1, into its switched-on position, as is illustrated in figure 3.

An alternative to the above described exemplary embodiment can be provided in that the movable contact piece 11 can move independently of a movement of the contact stem 8b and/or of the movable contact piece 5 of the first switching site 1. For this purpose, the movable contact pieces 5, 11 of the first switching site 1 and/or second switching site 2 can be moved by means of separate drives or special gearing mechanism arrangements .

Claims

1. A switching device having an interrupter path that comprises a first switching site and a second switching site having in each case contact pieces that are movable relative to one another, wherein: the first switching site is electrically connected in series to the second switching site by way of an axially displaceable contact pin; and a first movable contact piece is located on the axially displaceable contact pin in a sliding manner adapted to perform a switching process, wherein the first switching site and the second switching site are actuated by force; during a switching-off process the first switching site operates before the second switching site ; and during a switching-on process said first switching site operates after the second switching site.

2. The switching device as claimed in claim 1, wherein the first movable contact piece that is located on the axially displaceable contact pin is allocated to the second switching site, and wherein the axially displaceable contact pin is a part of a second movable contact piece of the first switching site .

3. The switching device as claimed in claim 1 or 2, wherein the first switching site is embodied as a vacuum interrupter.

4. The switching device as claimed in claim 3, wherein the axially displaceable contact pin is a contact stem of the first movable contact piece of the vacuum interrupter.