WO2021175546A1

WO2021175546A1 - Switching arrangement for medium voltage

Info

Publication number: WO2021175546A1
Application number: PCT/EP2021/053163
Authority: WO
Inventors: Stefan Hohmann; Philipp Koch; Daniel Pesch; Rene Zlydnik
Original assignee: Siemens Aktiengesellschaft
Priority date: 2020-03-03
Filing date: 2021-02-10
Publication date: 2021-09-10
Also published as: EP4091185A1; CN115210837A; DE102020202689A1; DE102020202689B4; EP4091185B1

Abstract

The present invention relates to a switching arrangement for medium voltage, having a load-break switch (1) having three switch positions for ON (40), OFF (41) and GROUND (42), wherein the switch position ON (40) switches a medium voltage connection to an output line (15) via a safety apparatus (12), and a ground switch (2) downstream of the safety apparatus (12) for grounding the output line (15), wherein the ground switch (2) is connected to the load-break switch (1) via a mechanical coupling apparatus (25, 31-37, 50-63), characterized in that the ground switch (2) is mechanically decoupled in the event of a switching operation of the load-break switch (1) from OFF (41) to ON (40).

Description

description

Switching arrangement for medium voltage

The invention relates to a switching arrangement for medium voltage according to the preamble of claim 1.

Switching arrangements for medium voltage are provided, for example, in local network transformer stations, which are often built as a compact housing with several modules for several fields of electrical equipment. For example, a housing with three switch panels can be provided for a ring-shaped medium-voltage network, namely a feed field, an output field and a transformer switch field to which the local network transformer is connected. The local network transformer in turn has several outlets for the low-voltage network. For example, a switchgear panel has typical dimensions for medium-voltage switchgear, i.e. usually a box-shaped construction with edge lengths between approx. 0.5 and approx. 2 m.

When working on electrical systems, certain safety regulations apply in order to rule out any risk to persons. Among other things, according to the so-called "5 safety rules", live parts of the electrical system must be safely grounded and short-circuited. This also applies to transformer feeders or switch-disconnector-fuse combinations (with earthing switches) in medium-voltage technology that the main circuit of the system is divided into two sections, e.g. by a fuse, as soon as no fuse is inserted or it has been triggered and the fusible link is disconnected. This occurrence makes it necessary that both sides of the divided main circuit must be earthed separately from each other, namely in front of and behind (or on both sides) the fuse. Such a system, which is used to ground the secondary side of the fuse, must not lead to any dielectric flashovers to the current-carrying components of the switchgear with the main switchgear in the on and off switch position. Furthermore, such a system must ensure a safe switch position display, ie if the operator on the front of the system is shown "Earth" by a visual display, the system must really be earthed. Controlling this second er function via a separate drive source does not make economic sense .

In the conventional switch-disconnector designs, the earthing function of three-position switch-disconnectors is integrated in the switching device or it is supplemented by a separate earthing switch with its own or shared drive system. Alternative solutions have so far provided for the switching shaft of a three-position load switching device (ON, OFF, EARTH) to be moved via the earthing switch, but in this case the earthing switch is also moved during all switch movements (ON, OFF, EARTH). In poorly insulating environments (without protective gas or SF _Ö -free electrically insulating protective gas with comparatively weak insulating effect), this requires a lot of installation space in order to allow the resulting idle movements. In addition, the switch-disconnector is influenced (braked) when it switches ON and OFF. The earthing switches are usually equipped with three switch blades / metal sheets, which each earth one phase and short-circuit via a shaft. At least one component is therefore required for each phase in order to establish this connection to the earth potential.

Such a switch disconnector is known from the document WO 2009/010359 A2. A three-phase combined switch-disconnector and earthing switch is presented, which is provided with a protective gas insulation in a metal housing. The earthing switch for earthing the output lines is driven via a mechanical coupling device. From the publication "Switchgear type 8DJH for secondary distribution networks up to 24 kV, gas-insulated - medium-voltage switchgear", Siemens AG 2017, Article No. EMMS-K1440- A211-A6, a transformer branch of a switchgear is known from page 18, in which in a load switch is an Er function integrated.

The object of the invention is to provide a switching arrangement for medium voltage that can be switched comparatively in a particularly space-saving and fast manner.

The invention solves this by means of a switching arrangement for telspannung according to claim 1.

Typically, a switching arrangement for medium voltage has a load break switch which can separate or switch on each phase to be switched with a separate switching mechanism. This can have three positions, namely OFF, ON and EARTH. For example, the switch each has a contact that is rotatably mounted and switched off in a neutral position (OFF), ie not making contact with a conductor. To switch on, the contact can be swiveled to one side to switch on medium voltage. In order to ground the downstream circuit part with the safety device, the contact can be swiveled to the other side. A ground contact is touched there.

In the context of the invention, medium voltage denotes, for example, voltages between 1 kV and 52 kV, preferably between 12 kV and 36 kV.

A safety device within the meaning of the invention is an electrical safety device which is suitable for breaking an electrically conductive connection when a design-related current threshold value is exceeded. For example, a fuse can be used. The safety device is connected in series between the switch-disconnector and the output line. The output line can, for example, have an external plug for establishing a connection to a downstream electrical equipment such as a transformer.

A mechanical coupling device in the sense of the invention is any device that is suitable by means of a kinematic chain of mechanical components to record a movement (couple) and to transmit it. The movement is decoupled at the destination. This means that the mechanical coupling device does not use an additional electrical drive and usually manages without additional electronic controls and corresponding electrical conductors that would have to be shielded or laid in an electrically insulated manner.

According to the invention, the load break switch and the earthing switch are mechanically coupled, that is to say that a switching action of the load break switch mechanically forces a movement of the earthing switch. In this case, however, it is now proposed not to transmit all switching operations of the switch disconnector or not to force a movement of the earthing switch for all switching operations. Rather, when the switch-disconnector switches from OFF to ON (and accordingly from ON to OFF), no movement of the earthing switch is forced. On the one hand, this has the advantage that a corresponding switching contact of the earthing switch only needs to be able to control two contact positions (earthed / ungrounded), which is advantageous with regard to the space required. In particular, when using a switching arrangement in a _{gas space insulated with sulfur hexafluoride-free (SF Ö} ) protective gas, the space saved is valuable because such protective gases typically insulate less electrically than SF ₆ and therefore comparatively larger insulation distances are required.

On the other hand, when the switch-disconnector is switched ON or OFF, no movement of the earthing switch is forced, which the moving masses are reduced and the switch-disconnector can be switched more quickly. In addition, there is less wear on the components and the switching speed is not affected.

In a further preferred embodiment of the switching arrangement according to the invention, the coupling device has a lifting rod, an axial rotary movement of a drive axis of the switch disconnector being kinematically coupled into a translatory lifting movement of the lifting rod. This design is advantageous because a loading movement within the switching arrangement can be transmitted in a space-saving manner by means of the lifting rod. A lifting rod within the meaning of the invention can have essentially any geometric shape and any cross-section, that is to say, for example, it can be designed as a cylinder shape or tube-like or in profile shape.

In a further preferred embodiment of the switching arrangement according to the fiction, the coupling device has a driver with a first driver means connected in a rotationally fixed manner to the drive axle, the first driver means being designed to grip a second driver means in the event of a switching operation of the switch disconnector from OFF to EARTHING and to translate the axial rotary movement into a translatory stroke movement, and in the case of a switching operation of the switch-disconnector from OFF to ON, the second entrainment means to be missed. For example, in a simple design, the first drive means can be a flat and narrow sheet metal or a rod with a small diameter, the first drive means being attached to the switch disconnector perpendicular to the axis of rotation of a drive shaft and correspondingly rotates when the switch disconnector is confirmed. The second entrainment means can be designed in a simple design as a projection which protrudes into the plane of rotation of the first entrainment means. Correspondingly, for example, when the drive shaft of the switch disconnector is rotated clockwise, which corresponds, for example, to switching to ground potential, the projection is gripped through the sheet metal and so that the lifting rod can be pulled. This actuates the earthing switch to establish an earth connection. When designing the switch disconnector for operation in the reverse orientation, ie disconnecting when rotating the drive shaft counterclockwise, the first and second means of taking with can be designed accordingly.

In a further development of the aforementioned embodiment, the first entrainment means is designed to fix the position of the second entrainment means in the event of a switching operation of the switch disconnector from OFF to ON. In other words, the first entrainment means causes a locking or blocking of a lifting movement of the lifting rod. This increases safety because, for example, incorrect switching operations of the earthing switch due to vibrations or earthquakes can be avoided.

In a further preferred embodiment of the switching arrangement according to the invention, the first entrainment means has a projection and the second entrainment means provides a point of engagement for the projection.

An alternative design, in which, for example, the first pick-up means has a sheet metal or a plate attached to the axis of rotation, on which or on which a projection arranged coaxially to the drive axis is moved in a plane of rotation, can also be used with advantage. Correspondingly, the second entrainment means can have a recess, a hook or, in the simplest case, a flat sheet metal as a point of attack, which is gripped and moved by the projection when the drive shaft of the switch disconnector rotates. This embodiment is advantageous because it allows a simple and reliable translation of a rotary movement into a train movement.

In a further preferred embodiment of the switching arrangement according to the Invention, the second entrainment means is arranged directly on the lifting rod. This is an advantage because of this Design can be implemented particularly easily. In a further development, for example, a guide for the lifting rod can be provided so that only a movement in one axis is possible, please include. Alternatively, the lifting rod can only be attached to both ends.

In a further preferred embodiment of the switching arrangement according to the Invention, the second entrainment means is arranged on a connecting piece which is connected to the lifting rod via a pivot point. This design has the advantage that a vertical distance between a longitudinal axis is bridged by the lifting rod and the second entrainment means. In other words, the installation position of the lifting rod can be selected more freely, which is desirable in terms of required isolation distances.

Furthermore, the connecting piece can be held in a guide such that when a force is transmitted to the lifting rod, bending forces on the lifting rod are essentially avoided. A particularly long service life of the switching arrangement is ensured due to a reduction in bending forces. This is particularly important, since gas-insulated systems are often used, which are sealed maintenance-free for up to 35 years.

In a further preferred embodiment of the switching arrangement according to the invention, the coupling device has a translation device which kinematically decouples a translational Hubbe movement of the lifting rod into an axial rotary movement of a drive shaft of the earthing switch. This is an advantage because in this way the movement of the drive axis of the switch disconnector can be transferred to the drive axis of the earthing switch in a very space-saving manner.

In a further preferred embodiment of the switching arrangement according to the Invention, the translation device has a rocker, the first end of which is rotatably connected to the lifting rod, and the second end of which is rotatable with a Connecting lever is connected, which is connected to the drive shaft of the earthing switch via a lever piece. This variant is advantageous because it enables good coordination of the acceleration forces when the earthing switch is switched on.

In a further preferred embodiment of the switching arrangement according to the Invention, a grounding arm is arranged on the drive shaft of the grounding switch, which is designed to make electrically conductive contact with at least one grounding point by means of an axial rotation of the drive shaft of the grounding switch and to ground the output line. An output line within the meaning of the invention is, for example, a so-called cable outlet line of the system.

In a further preferred embodiment of the switching arrangement according to the Invention, the grounding arm has a spring device which can be biased in the ungrounded state. For example, a leg spring can be provided, one leg of which is attached to the earthing arm and whose second arm is supported on a support point, for example on a housing of the switching arrangement. This variant has the advantage that the prestressed spring device overcomes the inertia of the earthing arm better, so that rapid earthing processes are made possible.

In a further preferred embodiment of the switching arrangement according to the invention, the switching arrangement has a three-phase design, so that three safety devices, three grounding points and three output lines are provided. This is an advantage because switching arrangements according to the invention are often used, for example, in local network stations in which three-phase medium voltage has to be transformed for the low-voltage distribution network.

In a further preferred embodiment of the switching arrangement according to the Invention, at least one earthing arm is designed for contacting at least two earthing points. The grounding points are, for example, round or cylindrical contacts made of a material that conducts electricity well, such as copper. This embodiment is particularly space-saving because fewer than three earthing arms have to be moved in order to reach the three earthing points (of each phase). This can be achieved, for example, by making a grounding arm at least in its end area so wide that it strikes against or between two grounding points. For example, a U-shaped web with wings bent back in the direction of the drive axis of the earthing switch can be provided at the free end of the respective earthing arm, the wings having a clamping effect with particularly good electrical contacting when the earthing arm is moved between two earthing points.

For example, one earthing arm can be used that reaches two earthing points and another earthing arm that only reaches one earthing point.

Alternatively, two grounding arms of the same type can be used next to each other, each contacting two grounding points, with both grounding arms each centrally between them contacting a grounding point of a phase.

A design with only one earthing arm, which has a wide web for contacting all earthing points of the phases, is also possible with advantage.

Notwithstanding the aforementioned embodiment, three grounding arms can be provided for the three phases of the switch who the.

In a further preferred embodiment of the switching arrangement according to the invention, the switching arrangement has a fluid-tight housing that is designed to be filled with an SF6-free protective gas. This is an advantage because SF ₆ - free shielding gases often have a lower electrical insulation capacity than sulfur hexafluoride (SF _Ö ), which makes larger insulation clearances necessary. Given Installation space, this means that all assemblies must be used in a particularly space-saving manner in order to obtain the necessary isolation distances.

In a further preferred embodiment of the switching arrangement according to the Invention, the safety device has a fuse. For example, a high-voltage high-performance fuse (HV fuse) can be used, as is known from Wikipedia (permanent link: https://de.wikipedia.Org/w/index .php? Title = fuse & oldid = l95819210) ). After a fuse has tripped, the output line is no longer earthed, which makes a second earthing switch necessary.

In a further preferred embodiment of the switching arrangement according to the Invention, the switching arrangement is designed for a transformer switchgear panel, to the output line of which a transformer can be connected. This is a part before, because a switch disconnector fuse combination is often required, especially in transformer panels, which requires a safety device.

It is clear to those skilled in the field of medium-voltage switching technology that the presented embodiments and other variants can be combined, supplemented or modified in many ways in order to implement the inventive concept of decoupling the switch-on process of the load switch on the earthing switch.

To better explain the invention show in the schematic representation

FIG. 1 shows a first basic circuit diagram of a known circuit arrangement, and

FIG. 2 shows a second basic circuit diagram of a known circuit arrangement, and FIG. 3 shows a first view of a switching arrangement according to the invention, and

Figure 4 is a second view of the Schaltan arrangement according to the invention, and

FIG. 5 shows a first view of a coupling device, and FIG. 6 shows a schematic representation of the layers of the coupling device according to FIG. 5, and

FIG. 7 shows the EARTHING switch position of the coupling device according to FIG. 5, and FIG

FIG. 8 shows the switch position OFF of the coupling device according to FIG. 5, and

FIG. 9 shows the ON switch position of the coupling device according to FIG. 5, and

Figure 10 is a view of a first translation device, and

FIG. 11 shows the OFF switch position of the transmission device according to FIG. 10, and

FIG. 12 shows the EARTH switch position of the transmission device according to FIG. 10, and FIG

Figure 13 is a view of a second translation device, and

FIG. 14 shows the OFF switch position of the transmission device according to FIG. 10, and

FIG. 15 shows the EARTHING switch position of the transmission device according to FIG. 10, and FIG FIG. 16 shows a first embodiment of a multiphase switching arrangement with two grounding arms, and

FIG. 17 shows a second embodiment of a multiphase switching arrangement with two grounding arms, and

FIG. 18 shows a third embodiment of a multiphase switching arrangement with two grounding arms, and

FIG. 19 shows a first view of a fourth embodiment of a grounding arm, and

FIG. 20 shows a second view of the embodiment according to FIG. 19, and

FIG. 21 shows a third view of the embodiment according to FIG. 19, and

FIG. 22 shows another embodiment of a multiphase switching arrangement with three grounding arms, and

FIG. 23 shows a multi-phase switching arrangement with several attachment positions for the coupling device.

FIG. 1 shows a so-called dummy circuit diagram of a known combination of switch disconnector 1 and second earthing function 7.13 in a single-phase representation. Line 3 is connected to a medium voltage network and leads into the load break switch 1, which has a contact 6, driven by an axial rotary movement of the drive shaft 5. The switch position OFF is shown. If the contact 6 is switched to a medium-voltage connection point 4, the switch position is ON. Voltage is then applied via a fuse 12 to a plug device 14 which has an outlet 15 for connecting a transformer. From a connection point 11 there is another line 13 to the load break switch 1. If the contact 6 is switched to a ground contact 8 at ground potential 9, the contact 6 also makes contact with the other line 13 and thus grounds the transformer outlet 15 in addition.

This is necessary because if the fuse 12 was triggered, it could only go as far as the connection point in the EARTH switch position

10 are grounded - seen from there, components lying "behind" the fuse 12, such as a transformer, would be unearthed. that in the case of a three-phase design, three electrically conductive connections must be made through the limited installation space of a module and appropriate isolation distances must be provided in the inert gas-insulated, encapsulated housing.

FIG. 2 shows another embodiment of a known switching arrangement in which the second earthing function is arranged as an independent earthing switching device 2 on the cable outlet 15 of the system. Via a kinematic chain 16, a movement of the contact 6 in the switch disconnector 1 is coupled into the earthing switch 2 and enables the connection point

11 to switch "behind" the fuse 12 to a second earthing point. The kinematic chain 16 can switch all phases at the same time. Isolation distances can be smaller or almost completely neglected if the kinematic chain 16 is at least partially made with non-conductive materials. However, it is disadvantageous that the earthing switch has to track every movement of the switch-disconnector, i.e. also the actually unnecessary switching operation from OFF to ON and vice versa Installation space is required because it can be moved along with it (without touching a mating contact). Figure 3 shows a first view of a switching arrangement according to the invention in the manner of a longitudinal section 21 through a Ge housing 22,23 with bottom 23 and first side wall 22. The load break switch 1 with drive shaft 5 is connected via a lifting rod 25 to a transmission device 26, which has a translational The lifting movement of the lifting rod 25 is kinematically decoupled into an axial rotary movement of a drive shaft of the earthing switch. In the center of the housing is a fuse 12 for one of the three phases of the switching arrangement is introduced.

Figure 4 shows a second, perspective view of the aforementioned switching arrangement. There are three grounding points 28 and the drive shaft 17 of the grounding switch with two Erdungsar men 27 is shown. A second side wall 24 can also be seen.

As indicated in FIGS. 3 and 4, the new system for grounding the cable outlet consists essentially of two flat gears and a shaft or drive shaft 17 with attachments or grounding arms 27 for short-circuiting and grounding.

The levers in the gears only transfer forces in one plane. The symmetrical structure of the power transmission also prevents lateral forces. This means that the levers and cam tracks can be built very flat. The required installation space can advantageously be minimized.

FIG. 5 shows a first view of a coupling device 25, 31, 32, 33, 34, 35, 36, 37. FIG. 6 shows, purely schematically, a greatly simplified representation of the layering of the various metal sheets or components.

The coupling device 25, 31, 32, 33, 34, 35, 36, 37 has, as it were, a first gear that can convert a rotary movement of the drive shaft 5 of the load break switch (with rear wall 30) into a translational movement of a lifting rod 25. A driver 31 is rotationally fixed to the drive axle 5 tied together. It has a projection 36 as a first entrainment means which is designed to engage in a second entrainment means 32. The second entrainment means 32 is designed as a bolt which can be grasped by the projection 36 when the drive shaft 5 is rotated clockwise. The bolt 32 is positively displaceable between the rear wall 30 and a fixedly attached cover plate 33 in a first guide channel 35 on a curved path.

When the switch disconnector is passed from the switch position OFF to EARTH or EARTH to OFF, the contour of the driver 31 takes the bolt 32 along the curved path in the guide channel 35 and thus converts the rotary movement of the switch into a translational stroke movement of the bolt 32. If, on the other hand, the switch-disconnector passes the switching positions OFF to ON or ON to OFF, the contour of the driver 31 forces the bolt 32 into its position, but does not move it further, so that only the driver 31 moves with the switch-disconnector shaft 5.

The bolt 32 is net angeord between two connecting pieces 34, which are ver via a pivot point 130 with the lifting rod 25 connected. The lifting rod 25 lies in turn between the two metal sheets of the connecting pieces 34. The connecting pieces 34 are held in a guide 37, 99 in such a way that when a force is transmitted to the lifting rod 25, bending forces on the lifting rod 25 are essentially avoided. The Füh tion 37,99 has two guide channels 37 in the two connec tion pieces 34 on. The connecting piece is displaceable via the guide channels 37, while a bolt 99 is fixedly attached between the rear wall 30 and the cover plate 33.

FIGS. 7 to 9 show switching positions 40, 41, 42 of the coupling device according to FIG.

In FIG. 8, the OFF switch position is denoted by the reference identifier 41. The projection 36 engages in the bolt 32. By rotating the drive shaft 43, the lifting rod 25 can be moved along the axis 44.

If the load break switch in FIG. 7 is switched to EARTH 42, the drive axle 5 rotates the driver 31 in a clockwise direction (e.g. between 10 ° and 90 °). This pulls the connec tion pieces 34 with it and thus moves the lifting rod 25 between the imaginary axes 45, 46 by the rod stroke 47.

If the load break switch in Figure 9 (from OFF 41 according to Figure 8) is switched to ON 40, the drive shaft 5 rotates the driver 31 counterclockwise (e.g. between 10 ° and 90 °). This does not pull the connecting pieces 34 with it, accordingly the connecting pieces 34 and the lifting rod 35 remain essentially in the same position as with AUS 41. However, the special geometry or cross-sectional shape of the driver 31 causes the bolt 32 to be locked in such a way that the lifting rod 25 is essentially fixed or not displaceable. For example, the driver 31 has for this purpose a locking device which, for example, has a bulge in radial extent. The locking device has the advantage that vibrations during operation, such as earthquakes etc., cannot inadvertently trigger an earthing and thus a short circuit.

FIG. 10 shows a view of a transmission device 50,51,52,53,54,55,56,57,58,59,60,61,62,63, which kinematically converts the translatory lifting movement of the lifting rod 25 into an axial rotary movement Drive shaft 17 of the earthing switch is decoupled. The switching position OFF or ON is shown. A base plate 50 and a holding plate 51 are designed as flat metal sheets and form a gap in which a coupling lever 63, a rocker 57, a connecting lever 53 and a lever piece 55 are arranged. The coupling lever 63 has a guide channel 62 for a bolt 61, the bolt 61 additionally being arranged in a guide channel 59 of the rocker 57. The rocker 57 is rotatably mounted at a pivot point 58. At the end of the rocker 57, which faces the connecting lever 53 abge, another guide channel 60 for the bolt 56 is provided. The bolt 56 is also forcibly guided in a guide channel 52 of the holding plate 51. The bolt 56 is connected to the connecting lever 53. At its other end, the connecting lever 53 is rotatably connected via a bolt 54 to the lever piece 55, which in turn is non-rotatably connected to the drive shaft 17 of the earthing switch.

This configuration of the kinematic chain in the area of the transmission device is consequently designed similar to the power transmission in steam locomotives, in which a piston movement is converted into a wheel rotation via a coupling linkage.

Through the shape and position of the cam tracks in the guide channels 52,59,60,62 and the rocker 57 (or the toggle lever) variable translations can be realized during the movement of the lifting rod 25 according to the principles of the lever laws. In addition, the gearbox has a freewheel in the earth position. On the one hand, the variable ratio ensures that the rod stroke is converted to a different angle than the output angle on the switch-disconnector. On the other hand, it ensures different force equilibria on the travel path, which favor any necessary braking of the switch-disconnector shaft in the event of a blockage. The freewheel ensures that the position of the coupled lever pieces 55 together with the drive shaft 17 does not change if the bolts continue to move in freewheel. This makes the earth position of the second deraxis 17 particularly insensitive to tolerances and enables an exact approach to the EARTH switch position. An additional stop is unnecessary.

Figures 11 and 12 show the two switching positions OUT 41 and EARTH 42 of the translation device. From OUT 41 to EARTH 42, the lifting rod 25 has the coupling lever 63 around the Rod stroke 47 is moved and thus the rocker 57 is pulled in the direction of the load break switch. As a result, the connecting lever 53 was pushed away from the coupling lever 63 in the direction of the drive axis 17, which caused a clockwise rotation 68 of the lever piece 55 about the drive axis 17 of the earthing switch.

FIG. 13 shows a further variant of a transmission device 51,53,54,55,57,58 which manages without guide channels. This design is therefore particularly easy to construct and particularly reliable and durable. The figure shows the earthed state in which, just as in the embodiment according to FIG. This mechanical configuration in the earthed state is comparatively particularly suitable for enabling safe contacting of the earthing point in the event of vibrations such as earthquakes etc.

14 and 15 show the switch positions AUS 41 and EARTH 42 of an earthing arm 72 with contact body 71. In the position AUS 41, the earthing arm 72 is pretensioned by means of a spring device 73, which is supported on the one hand on the earthing arm 72 and on the other hand on the housing base 23. A so-called leg spring is used. The load on the entire kinematic chain down to the switch and the drive is reduced. The leg spring is tensioned in the OFF position and releases its energy when switching from OFF to EARTH. When moving from EARTH to OFF, the leg spring is tensioned. Upon rotation 68 of the drive shaft 17 of the grounding switch, the contact body 71 is brought into electrically conductive contact with the grounding point 70 ge. In this way, the area of the switching arrangement which is arranged downstream of the fuse (not shown) is grounded. On the drive axis 17 is ge superimposed in an end region 74 of the base plate. Contact body 70, earthing arm 72 and earthing point 70 can be formed at least partially from copper, for example be in order to form a good electrically conductive connection. The axis 17 is used to form an electrically conductive connection to the earth potential.

Since the phases do not need to be separated when grounding, the sheets made of copper, for example, move between two adjacent phases and short-circuit them. A contact pressure force is guaranteed by overlapping the nominal span of the copper sheet and the electrodes. An additional spring element is not absolutely necessary. This structure means that only two small copper contacts are required for grounding the three Pha sen instead of the three that were usual up to now.

FIGS. 16 and 17 show an embodiment of a polyphase switching arrangement with two earthing arms 72, 82 which are attached to the drive shaft 17. Each earthing arm 72, 82 has a substantially U-shaped bent sheet metal 87, 88, 89, 90 as a contact body, which engages between two of the three earthing points 70, 80, 81. When switching to EARTH, the U-shaped plate can slide between two earthing points and is pressed together in the process. This ensures a clamped seat with an electrically conductive contact.

A variant is shown in FIG. 16 in which the earthing arms 72, 82 and contact bodies 87, 88 are each connected with two rivet connections 85. In Figure 17, however, a screw 86 is used to connect contact bodies 89, 90 and arms 72, 82. In addition, the metal sheets of the contact bodies 89, 90 are each slotted, which enables the electrical contact to be improved even further. FIG. 18 shows this in detail: each side of a contact body 89, 90 is divided into two sheets 92, 93, parallel to the drive axis 17.

FIGS. 19 to 21 show a further variant for the design of the earthing arms 71. A screw 132 holds a contact body 130 which, in contrast to the aforementioned variants, is not slotted to the end, but rather a lot has two recesses 132 (one per end). A transverse plate 134 additionally stabilizes the construction. In this embodiment, a displacement 135 of the contact body 130 transversely to the earthing arm 72 is possible, for example by providing an elongated hole in the transverse direction for the screw 132. This enables individual tolerance compensation of the contact bodies. As soon as the contact bodies move between the grounding points or electrodes, they automatically align themselves between the electrodes by moving transversely, thus ensuring an even distribution of force and better contact. With this design, larger production-related tolerances can advantageously be made possible and the reliability in operation can be increased.

FIG. 22 shows another embodiment of a multiphase switching arrangement with three grounding arms 100, 101, 102, each of which has two parallel metal sheets 104, 105, 106, 107, 108, 109. Each sheet metal is individually attached to the drive axle 17 with a screw connection 110. Each earthing arm 100,101,102 has a clamping screw 111,112,113, which each sets a distance 114 between the pairs of metal sheets 104,105,106,107,108,109. In contrast to the earthing arms explained above, provision is now made for the two metal sheets of an earthing arm to encompass an earthing point on the outside with a slight press fit.

FIG. 23 shows a longitudinal section through a multiphase switching arrangement with several attachment positions 123, 124, 125, 126 for the coupling device. In the embodiments explained in FIGS. 1 to 13, the first gear of the coupling device, that is to say for example also the driver on the axis 5, was spatially arranged in the area 123. This essentially corresponds to an attachment to a rear wall of the module housing for the load break switch.

As an alternative to this, however, the first transmission can also be arranged within the switch disconnector 1 between switching chambers for two phases, that is to say at positions 124 and 125. An arrangement on the front side, that is to say position 126, is also possible.

It is clear to the person skilled in the art that the embodiments presented here can advantageously be combined and modified without departing from the scope of the solution according to the invention. For example, a comparable saving in installation space can be achieved if a gearbox comparable to the transmission device with a rigid coupling is arranged on the load-break switch and a second gearbox with e.g. driver, first and second drive means etc. is arranged on the earthing switch. Correspondingly, with this design, mechanical decoupling would only take place in the immediate vicinity of the earthing switch when switching from OFF to ON (and vice versa) instead of as in the previously described embodiments of the switch-disconnector.

Claims

1. Switching arrangement for medium voltage, comprising a switch disconnector (1) with three switching positions for ON (40), OFF (41) and EARTH (42), the switching position ON (40) being a medium voltage connection via a fuse device (12) to an output line ( 15) switches, and an earthing switch (2) arranged downstream of the fuse device (12) for earthing the output line (15), the earthing switch (2) with the load-break switch (1) via a mechanical coupling device (25,31-37,50 -63) is connected, characterized in that the earthing switch (2) is mechanically decoupled from OFF (41) to ON (40) in the event of the switch-disconnector (1) switching.

2. Switching arrangement according to claim 1, characterized in that the coupling device (25,31-37,50-63) has a lifting rod (25), wherein an axial rotary movement of a drive shaft (5) of the switch disconnector (1) in a translatory lifting movement (44) of the lifting rod (25) is kinematically coupled.

3. Switching arrangement according to claim 1 or 2, characterized in that the coupling device (25, 31-37, 50-63) has a driver (35) connected in a rotationally fixed manner to the drive axle (5) with a first driver (36), wherein the first entrainment means (36) is designed to grip a second entrainment means (32) in the event of a switching operation of the switch disconnector (1) from OFF (41) to EARTH (42) and to translate the axial rotary movement into the translatory stroke movement (44) , and in the case of a switching operation of the switch disconnector (1) from OFF (41) to ON (40) the second entrainment means (32) to be missing.

4. Switching arrangement according to claim 3, characterized in that the first entrainment means has a projection (36) and that the second entrainment means provides a point of application (32) for the projection (36).

5. Switching arrangement according to claim 4, characterized in that the second entrainment means (32) is arranged directly on the lifting rod (25).

6. Switching arrangement according to claim 4, characterized in that the second entrainment means (32) is arranged on a connecting piece (34) which is connected to the lifting rod via a pivot point (130).

7. Switching arrangement according to one of claims 2 to 6, characterized in that the coupling device (25,31-37,50- 63) has a translation device (50-63) which kinema a translational lifting movement (44) of the lifting rod (25) table in an axial rotary movement (68) of a drive shaft (17) of the earthing switch (2).

8. Switching arrangement according to claim 7, characterized in that the translation device (50-63) has a rocker (57), the first end of which is rotatably connected to the lifting rod (25) ver, and the second end of which is rotatable with a connec tion lever ( 53), which is connected to the drive shaft (17) of the earthing switch (2) via a lever piece (55).

9. Switching arrangement according to claim 7, characterized in that a grounding arm (72,73,82,84-90,92,93,100-102,104-114) is arranged on the drive shaft (17) of the grounding switch (2) which is designed by means of an axial rotation of the drive shaft (17) of the earthing switch (2) to make electrically conductive contact with at least one earthing point (70) and to earth the output line (15).

10. Switching arrangement according to claim 9, characterized in that the earthing arm (72,73,82,84-90,92,93,100-102,104-114) has a spring device (73,84) which in the ungrounded state (40,41) can be prestressed.

11. Switching arrangement according to one of the preceding claims, characterized in that the switching arrangement is three-phase, so that three safety devices (12), three grounding points (70, 80, 81) and three output lines (15) are provided.

12. Switching arrangement according to claim 9, characterized in that at least one earthing arm (72,73,82,84-90,92,93) is designed for contacting two earthing points (70,80,81).

13. Switching arrangement according to one of the preceding claims, characterized in that the switching arrangement has a fluid-tight housing (22, 23) that is designed to be filled with a SF ₆ -free protective gas.

14. Switching arrangement according to one of the preceding claims, characterized in that the safety device has a fuse (12).

15. Switching arrangement according to one of the preceding claims, characterized in that the switching arrangement is designed for a transformer switchgear panel, to the output line (15) of which a transformer can be connected.