EP2546847B1

EP2546847B1 - Fast switch with Thomson coil and damping

Info

Publication number: EP2546847B1
Application number: EP11173993.4A
Authority: EP
Inventors: Per Skarby; Daniel Ohlsson; Jakub Korbel; Lars E Jonsson; Lars Liljestrand
Original assignee: ABB Technology AG
Current assignee: ABB Technology AG
Priority date: 2011-07-14
Filing date: 2011-07-14
Publication date: 2015-06-03
Anticipated expiration: 2031-07-14
Also published as: EP2546847A1

Description

Technical Field

The invention relates to a high or medium voltage switch comprising a switching assembly adapted to form a conducting path between a first and a second terminal.

Background Art

A switch of this type is disclosed in US 2004/0245857 . It has a switching assembly and a drive adapted to actuate the switching assembly. The drive comprises a plunger displaceable along a displacement direction and driven by a Thomson coil, i.e. a drive where a conducting member adjacent to a coil is subjected to a repulsive force upon application of a current pulse to the coil. The current pulse in the coil generates a varying magnetic flux, which in turn generates a current with opposite direction in the plunger. This generates a repulsive force between the coil and the plunger for driving the plunger away from the coil. This actuating principle is suitable to operate contact systems in electrical switches where a short breaking time is required.

Disclosure of the Invention

The problem to be solved by the present invention is to provide an improved switch of this type.
This problem is solved by the switch of claim 1. Accordingly, the switch comprises a first and a second terminal for applying the current to be switched. Further, it has a switching assembly having a first and a second configuration and a drive adapted to move the switching assembly from the first to the second and/or from the second to the first configuration. The switching assembly is structured such that

in a first configuration it forms one or more conducting paths between the terminals, i.e. the switch is in the closed, conducting configuration; and
in a second configuration it does not form the path, i.e. the switch is in its opened, nonconducting configuration.

The drive comprises a chamber enclosed by a wall and, arranged in the chamber, an at least partially conductive plunger moving along a displacement direction between a first and a second location. The plunger is mechanically connected, through a first opening of the wall, to the switching assembly for actuating the switching assembly. The drive further comprises a drive coil positioned adjacent to the plunger for acting as a Thomson coil and a current pulse generator adapted to generate a current pulse in the drive coil in order to drive the plunger away from the drive coil.
According to the invention, the drive further comprises one or more vents, in addition to the first opening, extending through the wall.
The presence of the vents allows for a controlled gas exchange between the chamber and its surroundings, which, in turn, allows a controlled dampening of the plunger motion. A suitably placed vent may e.g. reduce damping or increase it, as explained in the following.
Advantageously, the drive comprises at least one radial vent extending through the drive wall and opening into the chamber at an axial section of the wall. In that case, the mouth section where the radial vent enters the chamber is advantageously positioned such that it is at least partially and variably covered when the plunger travels between its first and said second locations. This allows to provide a position-dependent damping of the plunger motion.
In another advantageous embodiment, the drive comprises at least one axial vent extending through the drive wall and having a mouth section that opens into the chamber at a radial section of the wall. Such an opening is particularly suited as a relief opening for gas trapped when the plunger is moved against said radial wall section, thereby reducing a rebound of the plunger.
In yet another advantageous embodiment, the plunger divides the drive chamber into a first and a second compartment, wherein the drive further comprises a passage between the first and the second compartments. This design allows for a fluid exchange between the two sections in order to move the fluid from the section being compressed to the section being expanded during the stroke of the plunger.
If the switching assembly is arranged in a fluid-tight housing containing an electrically insulating fluid (i.e. a liquid or a gas), the drive is advantageously arranged within the housing, thus obviating the need for mechanical bushings. In that case, the vent or vents connect the chamber with the space surrounding the housing. In that case, the fluid that surrounds the switching assembly can also be used for damping the drive. This is particularly advantageous, if the fluid is a compressed gas, such as compressed SF₆, or an alternative high voltage insulation gas, because compressed gas has a comparatively high density and therefore strong damping effects.
The switch is advantageously used in high voltage applications (i.e. for voltages above e.g.72 kV), but it can also be used for medium voltage applications (between some kV and 72 kV).
Other advantageous embodiments are listed in the dependent claims, any combinations of dependent claims as well as in the description below.

Brief Description of the Drawings

The invention will be better understood and objects other than those set forth above will become apparent from the following detailed description thereof. Such description makes reference to the annexed drawings, which show exemplary embodiments only:

Fig. 1 shows a cross-sectional view of an exemplary switch,
Fig. 2 shows an enlarged cross-sectional view of the contact elements of the exemplary switch,
Fig. 3 shows a sectional view of a drive,
Fig. 4 shows a simplified cross section of a first embodiment of the drive,
Fig. 5 shows a cross section of a second embodiment of the drive,
Fig. 6 shows a cross section of a third embodiment of the drive illustrating some valve types, and
Fig. 7 shows schematically the position of the plunger as a function of time for various types of damping.

Modes for Carrying Out the Invention

Definitions:

The term "radial" in reference to the drive of the present device designates a direction radial (or perpendicular) to the displacement direction D.
The term "axial" in reference to the drive of the present device designates a direction axial (or parallel) to the displacement direction D.
An "axial section" of the wall of the drive is a part of the wall that extends substantially axially and confines the chamber of the drive radially.
A "radial section" of the wall of the drive is a part of the wall that extends substantially radially and confines the chamber of the drive axially.
The term "axial half" of the chamber of the drive assumes that the chamber is divided into two halves along a radially extending dividing plane extending through its middle. The term "top axial half" refers to the axial half closer to the switching assembly, while the term "bottom axial half" refers to the axial half that is farther away from the switching assembly.
The term "overpressure valve" designates a valve adapted to open when the pressure drop over the valve exceeds a threshold, while closing when the pressure drop of the valve falls below the threshold. The threshold may be zero or non-zero.

Description:

The exemplary switch of Fig. 1 comprises a fluid-tight housing 1 enclosing a space 2 filled with an insulating fluid, in particular SF₆ or air at elevated pressure or other insulating gas, e.g. fluoroketone or a mixture of air and fluoroketone, or an oil.
Housing 1 forms a GIS-type metallic enclosure and comprises two tube sections. A first tube section 3 extends along an axial direction A, and a second tube section 4 extends along a direction D, which is called the displacement direction for reasons that will become apparent below. Preferably, axial direction A is perpendicular or nearly perpendicular to displacement direction D. The tube sections are formed by a substantially cross-shaped housing section 5.
First tube section 3 ends in first and second support insulators 6 and 7, respectively. First support insulator 6 carries a first terminal 8 and second support insulator 7 carries a second terminal 9 of the switch. The two terminals 8, 9 extending through the support insulators 6, 7 carry the current through the switch, substantially along axial direction A.
Second tube section 4 ends in a first and a second cap 10 and 11, respectively.
First terminal 8 and second terminal 9 extend towards a center of space 2 and end at a distance from each other, with a switching assembly 12 located between them, at the intersection region of first tube section 3 with second tube section 4.
As can best be seen from Fig. 2, switching assembly 12 comprises a first set of contact elements 13a, 13b, 13c and a second set of contact elements 14a, 14b, 14c. In the embodiment shown here, each set comprises three contact elements, but that number may vary, and, for example, be two or more than three. The first and second set may also have different numbers of contact elements, e.g. two and three, respectively. Advantageously, the number is at least two contact elements per set. The contact elements of the two sets are stacked alternatingly, i.e. each contact element of one set is adjacent to two contact elements of the other set unless it is located at the end of switching assembly 12, in which case it is located between one contact element of the other set and one of the terminals 8, 9.
As shown in Fig. 2, each contact element comprises a plate-shaped insulating carrier 15, one or more conducting elements 16 and an actuator rod 17. In the embodiment shown here, each carrier 15 carries two conducting elements 16.
Figs. 1 and 2 show the switch in the closed state with the contact elements 13a, 13b, 13c, 14a, 14b, 14c in a first mutual position (corresponding to the first configuration of the switching assembly 12), where the conducting elements 16 align to form two conducting paths along axial direction A between the first and the second terminals 8, 9. The conducting paths carry the current between the terminals 8, 9. Their number can be greater than one in order to increase continuous current carrying capability.
The contact elements 13a, 13b, 13c, 14a, 14b, 14c can be moved along the displacement direction D into a second position, where the conducting elements 16 are staggered in respect to each other and do not form a conducting path (corresponding to the second configuration of the switching assembly 12). In the second position, the conducting elements 16' are separated from each other along direction D, thereby creating several contact gaps (here two times the number of contact elements 13, 14), thereby quickly providing a high dielectric withstand level.
To achieve such a displacement, and as best can be seen in Fig. 1, the actuator rods 17 are connected to two drives 18, 19. A first drive 18 is connected to the actuator rods 17 of the first set of contact elements 13a, 13b, 13c, and a second drive 19 is connected to the actuator rods 17 of the second set of contact elements 14a, 14b, 14c.
In the embodiment shown in Figs. 1 and 2, the switch is opened by pulling the actuator rods 17 away from the center of the switch, thereby bringing the conducting elements into their second, staggered position. Alternatively, the rods 17 can be pushed towards the center of the switch, which also allows to bring the conducting elements into a staggered position.
The drives 18, 19 operate on the repulsive Lorentz-force principle. Each drive is able to displace one set of contact elements along the displacement direction D. They are adapted and controlled to move the first and second sets in opposite directions at the same time in order to increase the relative travelling length and relative speed of displacement. An embodiment of a suitable drive is described in more detail below.
The drives 18, 19 are arranged in opposite end regions of second tube section 4.
As shown in Fig. 2, each terminal 8, 9 carries a contact plate 22 forming a contact surface 23 contacting the conducting elements 16 when the switch is in its first configuration. The contact plates 22 are mounted to the terminals 8, 9 in axially displaceable manner, with springs 20 elastically urging the contact surface 23 against the conducting elements, thereby compressing the conducting elements 16 in their aligned state for better conduction. In the embodiment of Fig. 2, helical compression springs 20 are used for this purpose, but other types of spring members can be used as well. Also, even though it is advantageous if there is at least one spring member in each terminal 8, 9, a compression force for the aligned conducting elements 16 can also be generated by means of a spring member or spring members in only one of the terminals 8, 9.
Fig. 3 shows a schematic sectional view of a drive 18, 19. The drive comprises a metal wall 25 enclosing a chamber 26. A plunger 27 is arranged within chamber 26 and held by a bistable suspension 28. Plunger 27 is connected by means of an adapter member 40 to the actuator rods 17 of one set of contact element 13a, 13b, 13c or 14a, 14b, 14c, with the actuator rods 17 and the adapter member 40 extending through a first opening 21 in wall 25. Adapter member 40 is dimensioned to have a cross section somewhat smaller than first opening 21, thereby forming a small gap 41 between adapter member 40 and opening 21 in order to tailor the damping properties of the drive, as will be described in more detail below.
Bistable suspension 28 comprises first and second pistons 29, 30 movable along bores 31, 32 in a direction perpendicular to displacement direction D, i.e. in radial direction. The pistons are pushed towards chamber 26 by means of first and second springs 33, 34. Each piston 29, 30 is connected to plunger 27 by means of a link 35, 36. Each link 35, 36 is formed by a substantially rigid rod, which is, at a first end, rotatably connected to its piston 29, 30, and, at a second end, rotatably connected to plunger 27.
The springs 33, 34, the pistons 29, 30 and the links 35, 36 together form several spring members biased against the edges of plunger 27. Since the springs 33, 34 urge the links 35, 36 against plunger 27, plunger 27 can assume two stable locations within bistable suspension 28, namely a first location as shown with solid lines in Fig. 3, as well as a second location as shown in dotted lines. The first location corresponds to the first configuration of the switching assembly, and the second location to the second configuration.
To operate plunger 27, first and second drive coils 37, 38 are arranged at opposite sides of chamber 26. Further, plunger 27 is of a conducting material, at least on its surfaces facing the drive coils 37, 38. In the first and second stable locations, plunger 27 is adjacent to first and second drive coil 37, 38, respectively.
Hence, when plunger 27 is e.g. in its first location and a current pulse is sent through first drive coil 37, a mirror current is generated within plunger 27, which leads to a repulsive force that accelerates plunger 27 away from first coil 37. The kinetic energy imparted on plunger 27 in this manner is sufficient to move plunger 27 against the bistable suspension mechanism 28 to its second location adjacent to second drive coil 38.
In the embodiment of Fig. 1, the two drives 18, 19 should be operated synchronously. A pulse generator 39 (see Fig. 1) is provided for this purpose. Pulse generator 39 is adapted to generate concurrent current pulses to the first drive coils 37 of both drives 18 and 19 for opening the switch, as well as concurrent current pulses to the second coils 38 of both drives 18 and 19 for closing the switch.
Advantageously and as already mentioned, a concurrent operation can easily be achieved by electrically arranging the first drive coils 37 of both switching drives in series, as shown by the feed lines between the drives 18, 19 and pulse generator 39 in Fig. 1. Similarly, the second drive coils 38 of both switching drives should advantageously be arranged in series as well.
As can be seen in Fig. 3, each drive coil 37, 38 is, on a side facing away from plunger 27, embedded in an electrically insulating coil support 42. Coil support 42 abuts, on its side facing away from drive coil 37, 38, against metal wall 25. Thus, when the drive is operated and coil 37 is pushed against coil support 42, the corresponding force is directly transferred to wall 25, which can be made of a stronger material than coil support 42.
As can also be seen from Fig. 3, each drive coil 37, 38 is advantageously formed by a wire having rectangular cross section in order to optimally use available space.
As depicted in Fig. 3, plunger 27 is further provided with at least one cavity 43, which allows to reduce its weight.

Damping:

As mentioned, drives 18, 19 are advantageously provided with various vents and other means adapted to tailor a damping of the motion of plunger 27. The exact design of these means depends on the specific details of the drive and goals to be achieved. In the following, some examples of such means are provided. It must be noted that these means can be used individually or in various combinations.
In the embodiment of Fig. 3 as well as in the schematic representation of this embodiment in Fig. 4, the drive is provided with two radial vents 44, 45 as well as an axial vent 46 and a passage 47.
Each radial vent 44, 45 extends through an axial section 48 of wall 25. It has a mouth section 49 opening into chamber 26. The mouth sections 49 can be covered to a varying degree by plunger 27 depending on the current position of plunger 27. In the embodiment of Fig. 4, for example, the mouth section of first radial vent 44 is covered (or at least "more covered") by plunger 27 when plunger 27 is in its first location, while it is uncovered (or at least "less covered") when plunger 27 is in its second location. The opposite is true for second radial vent 45.
This design generates a non-uniform damping during the stroke of plunger 27. For example, when plunger 27 is driven from its first location (as shown in Fig. 4 in solid lines) to its second position (shown in dotted lines), the first compartment 50 between plunger 27 and first coil 37 expands while the second compartment 51 between plunger 27 and second coil 37 shrinks. At the beginning, second radial duct 45 is open and the fluid in second compartment 51 can escape through it when plunger 27 starts to move, such that plunger 27 can be accelerated easily until it reaches a position where the switch is sufficiently open. Then plunger 47 starts to block second radial vent 45. Now, pressure can build up in second compartment 51, which decelerates plunger 27 and damps its impact against radial wall section 52. On the other hand, when plunger 27 is driven from its second to its first location, the fluid in first compartment 50 escapes through first radial vent 44 until that vent is blocked by plunger 27, such that the pressure builds up in the first compartment for damping the impact of plunger 27 against the top wall of compartment 26.
Thus, by using at least two radial vents 44, 45 at different axial locations along displacement direction D, damping can be tailored for both stroke directions of plunger 27. For that purpose, the following conditions are advantageously met:

when plunger 27 is in its first location, the mouth of first radial vent 44 is covered to a larger degree than the mouth section of second radial vent 45, and
when plunger 27 is in its second location, the mouth of first radial vent 44 is covered to a smaller degree than the mouth section of second radial vent 45.

As can further be seen from Figs. 3 and 4, the drive comprises at least one axial vent 46 extending through the radial section 52 of wall 25. Axial vent 46 allows a passage of fluid from second compartment 51 when the second compartment 51 is being compressed. Advantageously, the cross section of the second radial vent 45 (i.e. of the vent or vents whose mouth section 49 is located in the axial half of chamber 26 adjacent to axial vent 46) has a total cross section larger than the axial vent. In that case, plunger 26 starting to cover second radial vent 45 makes a substantial difference to the flow of fluid escaping from the shrinking second compartment 51. The purpose of axial vent 46 is to allow fluid to escape when the volume of the second compartment 51 becomes very small, thereby preventing plunger 27 from bouncing back after reaching its second location.
Further, as mentioned above, drive 18, 19 comprises a passage 47, which extends between the first and second compartments 50, 51. This passage 47 can extend through plunger 47 itself, but it is advantageously formed by a gap located radially between plunger 27 and wall 25. This gap extends at least partially or even completely around plunger 27. The purpose of passage 47 is to allow for a fluid exchange between the compartments 50, 51, while one expands while the other shrinks.
Advantageously, however, the total cross section of passage 47 is smaller than the total cross section of the radial vents 44, 45. In particular, it is smaller than the total cross section of the radial vent or radial vents ending in the bottom axial half of chamber 26 and smaller than the total cross section of the radial vent or radial vents ending in the top axial half of chamber 26. In that case, plunger 26 starting to cover any of the radial vents 44, 45 makes a substantial difference to the flow of fluid escaping from the shrinking compartment.
In the embodiment of Fig. 4, the free cross section (i.e. the cross section available for fluid transport) of the radial vents 44, 45 varies while plunger 27 travels from the first to the second or from the second to the first location.
Similarly, with a simple design change, the free cross section of passage 47 can also be made to vary. This is illustrated in Fig. 5, where a projection 53 in axial wall 48 projects into passage 47 while plunger 27 passes it. In the embodiment of Fig. 5, projection 53 is arranged substantially in the axial center of axial wall 48, and its length is such that plunger 27 in its first location is above projection 53 and in its second location it is below projection 53. Hence, the cross section of passage 47 decreases while plunger 47 is passing projection 53, thus reducing the fluid exchange between the compartments 50 and 51. In particular, when plunger 27 moves from its first to its second location, pressure in second compartment 52 can build up, thereby breaking plunger 27, until plunger 27 has fully passed projection 53, after which the cross section of passage 47 increases, thereby allowing to quickly reduce the pressure in second chamber 51.
Fig. 5 shows a further measure of interest, namely a design where the free cross section of axial vent 46 varies while plunger 27 travels between the first and second locations. This measure comprises an axial protrusion 54 extending from plunger 27. This protrusion 54 enters and exits axial vent 46 when plunger 27 is moved between its first and second locations. Depending on the shape and size of protrusion 54, the free cross section of axial vent 46 can be controlled for optimum damping properties.
It must be noted that the device can also comprise axial vents 46 in the axial wall that is opposite to axial wall 52, and, optionally, suitable protrusions can be arranged on plunger 27. This is indicated in Fig. 5 with dashed lines at 46'.
In the embodiments of Figs. 4 and 5, the free cross section of the vents 44, 45, 46 are varied by directly covering/uncovering them with plunger 27 or parts attached to plunger 27. Alternatively, or in addition thereto, at least one vent valve arranged at or in at least one of the vents can be used. For the sake of illustration, two different such vent valves are shown in Fig. 6:

A first example of a vent valve is an overpressure valve 55. In the embodiment shown, overpressure valve 55 opens when the pressure difference between compartment 50 and the space surrounding drive 18, 19 is positive. It can e.g. be formed by a spring plate pressed over the outward end of the radial vent.
A second example can be that a vent valve has an actuator 57 actuated when plunger 27 travels between its first and second locations. It can e.g. be an electric valve controlled by a control unit.

Notes:

It must be noted that a drive of the present design can also be used in switches different from the one shown in Figs. 1 and 2. In particular, a switch using the present drive can also contain a single drive only, or it can use a different type of switching assembly. A switch using the present drive can, for example, be a fast acting earthing switch, a disconnector, a combined disconnector and earthing switch (three-position switch), a load-break switch, a circuit breaker or the like.
In general, damping should be designed such that plunger 27 moving from its first to its second location suffers only weak or no deceleration until it has reached a position where the switch is sufficiently open. Only then should the deceleration set in. Deceleration is caused by a pressure difference between the first and the second compartments 50, 51. This pressure difference should be chosen to be sufficiently large such that it is able to decelerate plunger 27 substantially, so its impact against section 52 of the wall is softened. However, shortly before plunger 27 reaches its second location, the pressure difference should be decreased again, in order to prevent a rebound also known as contact back-travel.
Fig. 7 shows the position of the plunger as a function of time for an optimized case ("favourable damping") as well as for a case with rebound ("undamped travel with rebound"). A strong rebound has various disadvantages, such as:

There is a risk of mechanical damage if the impact speed at end-of-stroke is too high.
The back-travel during rebound can lower the dielectric strength of the contact gap.
The rebound process gives rise to a long settling time of the plunger on the coil. Only after the plunger has settled on the coil, the switch can be closed again, i.e. a long settling time increases the time until the switch can be closed again.

For an opening operation the main requirement is to have enough dielectric withstand after the interruption, and a certain rebound is allowed. The main reason for avoiding a rebound is to minimize impact forces and quickly position the plunger for the close operation.
For closing, the allowed rebound is defined by the overlap between the sliding contact elements 16. The conducting path 24 has to remain closed during rebound.
The fluid in chamber 26 can be a liquid or a gas. For the reasons given above, it is advantageously a compressed gas. The cross sections of the openings can be optimized according to the properties of the fluid in use, i.e. the fluid density and viscosity.
Gap 41 (see Fig. 3) between adapter member 40 and wall 25 can also serve as an escape route for fluid from chamber 26, similar to axial vent 46 on the opposite side of the drive, and can also form an axial vent 41. This allows a substantially symmetrical switching behaviour of the drive 18, 19, i.e. similar damping when moving plunger 27 from its first to its second location as when moving it from its second to its first location. However, an asymmetric design can be used as well, in particular if the travel speed of plunger 27 can be slower in one direction than in the other direction.
In the embodiments shown so far, there are two coils per drive for driving the plunger in opposite directions. It must be noted that the invention can also be carried out with a drive with only one coil. In that case, the movement of the plunger into the direction towards the coil can be generated by other means, e.g. elastically, pneumatically, etc., or there may be two drives for each actuator.
Also, only one set of contact elements of the switch could be movable, while the other one is stationary.
While there are shown and described presently preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

Reference numbers

1: housing
2: space
3, 4: tube sections
5: housing section
6, 7: support insulators
8, 9: terminals
10, 11: caps
12: switching assembly
13a, 13b, 13c: first set of contact elements
14a, 14b, 14c: second set of contact elements
15: insulating carrier
15a, 15b: axial surfaces of insulating carrier
16, 16': conducting elements
17: actuator rods
18: drive
19: drive
20: springs
21: first opening
22: contact plate
23: contact surface
25: wall
26: chamber
27: plunger
28: bistable suspension
29, 30: pistons
31, 32: bores
33, 34: springs
35, 36: links
37, 38: drive coils
39: pulse generator
40: adapter member
41: gap
42: coil support
43: cavities
44, 45: radial vent(s)
46, 46': axial vent(s)
47: passage
48: axial section of wall
49: mouth section
50, 51: first and second compartment
52: radial section of wall
53: projection
54: protrusion
55, 56: vent valves

Claims

A high or medium voltage switch comprising
a first and a second terminal (8, 9),
a switching assembly (12) having a first and a second configuration, wherein in said first configuration said switching assembly (12) forms at least one conducting path between said terminals (8, 9) and wherein in said second configuration said switching assembly (12) does not form a conducting path between said terminals (8, 9),
at least one drive (18, 19) for moving said switching assembly (12) from said first to said second and/or from said second to said first configuration, wherein said drive (18, 19) comprises
a chamber (26) enclosed by a wall (25),
an at least partially conductive plunger (27) arranged in said chamber (26), movable along a displacement direction (D) between a first and a second location and connected, through a first opening (21) in said wall (25), to said switching assembly (12),
wherein the plunger (27) is in a first location if the switching assembly (12) is in the first configuration, and wherein the plunger (27) is in a second location if the switching assembly (12) is in the second configuration,
a first drive coil (37) and a second drive coil (38) positioned adjacent to said plunger (27) at opposite sides of the chamber (26), and
a current pulse generator (39) adapted to generate a current pulse in said drive coils (37, 38) for driving said plunger (27) away from one drive coil (37) to the other drive coil (38) and vice versa,
characterized in that the chamber (26) comprises one or more vents (44, 45, 46, 46') extending through said wall (25), and
in that said switching assembly (12) is encapsulated in a fluid-tight housing (1), wherein said fluid-tight housing (1) surrounds a space (2) containing an electrically insulating fluid, wherein said switching assembly (12) is arranged in said space (2), wherein said drive (18, 19) is arranged within the housing (1) in said space (2), and
wherein said one or more vents (44, 45, 46, 46') extend between said chamber (26) and said space (2) such that a plunger position-dependent gas exchange between the chamber (26) and the space (2) takes place when the plunger (27) travels between its first and second location and vice versa.
The switch of claim 1 comprising at least one radial vent (44, 45) extending through said wall (25) and having a mouth section (49) opening into said chamber (26) at an axial section (48) of said wall (25).
The switch of any of the preceding claims, wherein a or said radial vent (44, 45) has a mouth section (49) opening into said chamber (26), wherein said mouth section (49) is at least partially covered when said plunger (27) travels between said first and said second locations, and in particular wherein said mouth section (49) is more covered when said plunger (27) is in said second location than when said plunger (27) is in said first location.
The switch of any of the preceding claims comprising at least two radial vents (44, 45) at different axial locations along said displacement direction (D), wherein
when said plunger (27) is in said first location, the mouth section (49) of a first of said radial vents (44, 45) is covered to a larger degree than the mouth section (49) of a second of said radial vents (44, 45), and
when said plunger (27) is in said second location, the mouth section (49) of the first radial vent (44) is covered to a smaller degree than the mouth section (49) of the second radial vent (45).
The switch of any of the preceding claims, comprising at least one axial vent (41, 46, 46') extending through said wall (25) and having a mouth section opening into said chamber (26) at a radial section (52) of said wall (25).
The switch of claim 5 further comprising a protrusion (54) axially extending from said plunger (27), wherein said protrusion (54) enters and exits said axial vent (46, 46') when said plunger (27) is moved between said first and second locations.
The switch of any of the claims 5 or 6 and of claim 2, wherein said radial vent or radial vents (44, 45) has or have a total cross section larger than said axial vent or axial vents (46, 46').
The switch of any of the preceding claims wherein said plunger (27) divides said chamber (26) into a first and a second compartment (50, 51), and wherein said drive (18, 19) further comprises a passage (47) between said first and said second compartments (50, 51).
The switch of claim 8 wherein said passage (47) is formed between said plunger (27) and said wall (25) and forms a gap (41), wherein said gap (41) extends at least partially around said plunger (27).
The switch of any of the claims 8 or 9 wherein a total cross section of said passage (47) varies when said plunger (27) travels between said first and second locations.
The switch of any of the claims 8 to 10 and of claim 2 wherein said passage (47) has a total cross section smaller than a total cross section of said radial vent or radial vents (44, 45).
The switch of any of the preceding claims, further comprising at least one vent valve (55, 56) arranged at or in at least one of said vents, and in particular wherein said vent valve (55, 56)
is an overpressure valve (55), or
has an actuator (57) actuated when said plunger (27) travels between said first and second locations.
The switch of any of the preceding claims, wherein a free cross section of at least one of said vents (44, 45, 46, 46') varies when said plunger (27) travels between said first and said second locations.
The switch of any of the preceding claims, wherein said plunger (27) is arranged in a bistable suspension (28), with said first and second location forming stable states of said bistable suspension (28).
The switch of any of the preceding claims, wherein said fluid is a compressed gas, in particular compressed SF₆, compressed air, fluoroketone, or a mixture of air and fluoroketone.