Switching device

Abstract

Disclosed herein is a switching device comprising switching means. The switching means comprises a vacuum interrupter and a disconnector switch connected in series. The switching device also comprises an operating mechanism configured to open and close the switching means and an actuating shaft configured to rotate about an axis to actuate the operating mechanism. The actuating shaft is configured to rotate in a first direction about the axis from a first position to a second position to cause the operating mechanism to close the switching means, wherein the operating mechanism is configured to close the disconnector switch before closing the vacuum interrupter. The actuating shaft is also configured to rotate in a second direction about the axis from the second position to the first position to cause the operating mechanism to open the switching means, wherein the operating mechanism is configured to open the vacuum interrupter before opening the disconnector switch. A method of operating the switching device is also disclosed.

Description

[0001] Switching device

[0002] Field

[0003] This relates to a switching device, and in particular a switching device comprising a disconnector switch arranged in sequence with a vacuum interrupter.

[0004] Background

[0005] When switching devices open, an arc can be generated between the separating contacts. Many devices therefore contain an electrical insulating medium. Arc interruption performance during switching, as well as dielectric withstanding under service positions, are essential performance criteria for the insulation medium of switchgears (including but not limited to medium voltage switch gears). Sulphur hexafluoride (SF6) is widely used as an insulating medium due to its high dielectric properties.

[0006] However, SF6 is a strong greenhouse gas. It is therefore desirable to replace SF6 with other insulating mediums, such as air component mixtures, dry air and oil. The dielectric and arc suppression performance of air component mixtures are lower than SF6, and so air component mixtures are currently only used in medium voltage applications (about 24 kV). For higher voltage applications (about 36kV), SF6 is still widely used in place of other insulating mediums. It is therefore desirable to provide a switching device which can operate at a range of voltage levels whilst using a variety of electrical insulating mediums.

[0007] EP3614409A1 refers to a switch and disconnector connected in series, such that the opening of the switch occurs before the opening of the disconnector in a breaking operation, and the closing of the disconnector occurs before the closing of the switch in a making operation (the disconnector closes the circuit with no load). It is stated that this arrangement can be disadvantageous for the switch contacts, decreasing the lifetime of the switch. EP2244275A1 discloses an alternative arrangement in which a vacuum switch and a disconnector which are connected in series, such that the opening of the vacuum switch occurs before the opening of the disconnector in a breaking operation, but the closing of the vacuum switch occurs before the closing of the disconnector in a making operation. This arrangement can increase the lifetime of the (vacuum) switch, but decrease the lifetime of the disconnector.

[0008] An alternative arrangement that can allow to use insulating mediums other than SF6 is described in EP3961668A1, which uses electric arc blowing means to extinguish a generated arc. Contamination due to ambient radicals will appear after each switching, which poses a risk for the ambient electrical performance as well as a change in the insulation level in the medium and long term.

[0009] Another arrangement that can allow to avoid the use of SF6 are shunt VI solutions, such as those described in WO2022229553 and EP405387A1, in which a vacuum switch is arranged in parallel with a disconnector. In known shunt VI arrangements, the VI is only used for breaking under nominal current conditions, and short circuit closing operation is performed with conventional copper contact. This can cause contact adhesion due to possible melting as a result of the high current. The vacuum switch must withstand the TRV (transient recovery voltage) of the breaking but doesn't need to have short circuit making capacity, short time current withstand and continuous current withstand; a smaller vacuum switch may therefore be used. However, due to the small size of Vis used in shunt VI technologies, there are disadvantages in terms of tracking on the surface, especially in capacitive tests. Moreover, the complex structure can create electrical field problems in basic insulation level (BIL) tests.

[0010] It is desirable to provide an alternative switching device which overcomes some of these disadvantages.

[0011] Summary

[0012] Disclosed herein is a switching device and a method of operating the same. Aspects of the invention are set out in the appended independent claims, with optional features set out in the dependent claims appended thereto.

[0013] Disclosed herein is a switching device comprising switching means. The switching means comprises a vacuum interrupter and a disconnector switch connected in series. The switching device also comprises an operating mechanism configured to open and close the switching means and an actuating shaft configured to rotate about an axis to actuate the operating mechanism. The actuating shaft is configured to rotate in a first direction about the axis from a first position to a second position to cause the operating mechanism to close the switching means, wherein the operating mechanism is configured to close the disconnector switch before closing the vacuum interrupter. The actuating shaft is also configured to rotate in a second direction about the axis from the second position to the first position to cause the operating mechanism to open the switching means, wherein the operating mechanism is configured to open the vacuum interrupter before opening the disconnector switch. The vacuum interrupter and disconnector switch connected in series work sequentially relative to each other, allowing the switching device to use the vacuum interrupter (or VI) for both opening and closing operations. This enables the disconnector switch to be opened and closed at no load. By providing a no load disconnector in this way, there is no wear at the disconnector contacts (other than mechanical impacts). There is also no contamination of the insulating medium and, in the case of a dielectric medium (such as air) no contact erosion and no generation of H2O, CO or CO2 due to energy from any generated arc. The contamination of insulation medium under arc energy is an important challenge in current technology of switchgears, and can affect both the short and long term performance of the switch. For example, the outputs of chemical reactions of the dielectric medium under arc conditions can reduce the dielectric strength and can cause failures over time. These disadvantages can be obviated with a no load disconnector.

[0014] The present approach performs the opening and closing I fault making through the vacuum interrupter, or VI. Performing arc interruption and closing operations through a vacuum interrupter prevents contamination of the insulating medium, and can therefore enable safe operation of the switching device within the limits of insulating mediums such as air or air mixtures. Higher dielectric performance can therefore be provided. As such, devices for higher voltage applications can be provided without an SF6 insulating medium. Moreover, this arrangement allows the VI and disconnector switch to be operated sequentially by a single shaft, without requiring further operator input; this simple architecture within the switch can allow the number of components to be reduced, thereby reducing assembly and manufacturing cost.

[0015] In some implementations, the switching device further comprises an earthing switch. The operating mechanism is further configured to open and close the earthing switch without actuating the switching means. In this way, the earthing function is performed by the switching device, and is integrated into the structure of the device. The operating mechanism configuration separates the movements of the VI, disconnector and earthing switch, enabling a safe operation of the device.

[0016] Optionally, the actuating shaft is configured to rotate in the second direction from the first position to a third position to cause the operating mechanism to close the earthing switch. Optionally, the actuating shaft is configured to rotate in the first direction from the third position to the first position to cause the operating mechanism to open the earthing switch. By integrating the earthing function into the structure of the switching device, and driving the different functions by the same, single, shaft that drives the VI and disconnector switch, operation of the device can be simplified. The number of parts can also be reduced, thereby reducing assembly and manufacturing cost.

[0017] In some implementations, the operating mechanism comprises a transmission component rigidly coupled to the actuating shaft, wherein rotation of the transmission component drives the opening and closing of the disconnector switch.

[0018] In some implementations, the disconnector switch comprises a disconnector assembly configured to rotate about a second axis. The disconnector assembly can cause the opening and closing of the disconnector switch. Optionally, during closing of the disconnector switch, the disconnector assembly is configured to rotate in the first direction about the second axis. Optionally, during opening of the disconnector switch, the disconnector assembly is configured to rotate in the second direction about the second axis.

[0019] In some implementations, rotation of the transmission component drives the disconnector assembly to open and close the disconnector switch. Optionally, the operating mechanism further comprises one or more linkages coupled between the transmission component and the disconnector assembly, the one or more linkages configured to cause rotation of the disconnector assembly about the second axis in response to rotation of the transmission component.

[0020] In some implementations, the disconnector switch further comprises a spring assembly. Optionally, during closing of the disconnector switch, rotation of the transmission component causes the spring assembly to compress. Optionally the spring assembly and the one or more linkages are configured such that, once the disconnector assembly has rotated a predetermined amount in the first direction, the compressed spring assembly is configured to urge the disconnector assembly to rotate in the first direction about the second axis, the urging independent of the rotation of the transmission component.

[0021] This arrangement can provide a snapping action, with the one or more linkages and the spring assembly driving the disconnector switch to close quickly, as well as ensuring good contact between the disconnector switch with electrical contacts of the device through the automatic (spring assembly triggered and driven) overturning of the disconnector assembly. This can help to reduce or prevent accidental opening of the disconnector switch due to e.g. external shocks or vibrations. Moreover, the double toggle spring mechanism drives the disconnector assembly independently of the magnitude of the torque applied through the operating mechanism, allowing the disconnector to be driven more efficiently. This arrangement also allows the entire load applied to the operating mechanism to be used to close the VI, operating the VI more efficiently. Moreover, the double toggle spring mechanism provides sufficient speed and contact pressure in order to handle short circuit making magnetic forces. No additional spring is needed on the operating mechanism side.

[0022] In some implementations, during opening of the disconnector switch, rotation of the transmission component causes the spring assembly to compress. Optionally the spring assembly and the one or more linkages are configured such that, once the disconnector assembly has rotated a predetermined amount in the second direction, the compressed spring assembly is configured to urge the disconnector assembly to rotate in the second direction about the second axis, the urging independent of the rotation of the transmission component.

[0023] This arrangement can provide a snapping action, with the one or more linkages and the spring assembly driving the disconnector switch to open quickly, as well as ensuring isolation of the disconnector switch from the electrical contacts of the device in the open position through the urging or biasing of the disconnector switch towards the open position. This can help to reduce or prevent accidental closing of the disconnector switch due to e.g. external shocks or vibrations.

[0024] In other words, the one or more linkages and the spring assembly can form a double toggle switch mechanism that provides a snapping action at both closing and opening operations of the disconnector switch.

[0025] In some implementations, the operating mechanism comprises a cam rigidly coupled to the actuating shaft, the cam configured to drive opening and closing of the vacuum interrupter. Optionally, the vacuum interrupter comprises a rod, the rod comprising a cam follower configured to engage with a cam surface of the cam. Movement of the cam follower in response to rotation of the cam drives the opening and closing of the vacuum interrupter via the rod.

[0026] Optionally, the cam and transmission component are separate components, both rigidly coupled to the actuating shaft. By providing an arrangement in which actuation of the VI and disconnector switch is initiated by a single user input (rotation of the shaft), but then independently controlled by different mechanisms, operation of the switching device can be more easily fine-tuned. One or more interlocks may also be provided between the different mechanisms to ensure that the VI is shut before closing the disconnector during a closing / making operation (and vice versa during an opening / breaking operation). In other examples, the cam and the transmission component are integrally formed as a single component, the single component configured to facilitate the sequential operation of the VI and disconnector switch. The operating mechanism configuration separates and interlocks the movements of the VI, disconnector and earthing switch, enabling a safe operation of the device.

[0027] In some implementations, the earthing switch comprises an earthing assembly configured to rotate about a third axis. The earthing assembly can cause the opening and closing of the earthing switch. Optionally, during closing of the earthing switch, the earthing assembly is configured to rotate in the second direction about the third axis. Optionally, during opening of the earthing switch, the earthing assembly is configured to rotate in the first direction about the third axis.

[0028] The use of an earthing assembly and disconnector assembly as described herein, with double separated shafts / axes operated by a single operating mechanism can maximise dielectric distances, and thereby improve dielectric performance.

[0029] In some implementations, rotation of the transmission component further drives the opening and closing of the earthing switch. Optionally, rotation of the transmission component drives the earthing assembly to open and close the earthing switch. Optionally, the operating mechanism further comprises one or more second linkages coupled between the transmission component and the earthing assembly, the one or more second linkages configured to cause rotation of the earthing assembly about the second axis in response to rotation of the transmission component.

[0030] In some implementations, the earthing switch further comprises a second spring assembly. Optionally, during closing of the earthing switch, rotation of the transmission component causes the second spring assembly to compress. Optionally the second spring assembly and the one or more second linkages are configured such that, once the earthing assembly has rotated a predetermined amount in the second direction, the compressed second spring assembly is configured to urge the earthing assembly to rotate in the second direction about the third axis, the urging independent of the rotation of the transmission component. This arrangement can provide a snapping action, with the one or more second linkages and the second spring assembly driving the earthing switch to close quickly, as well as ensuring good contact between the earthing switch with earthing contacts of the device through the automatic (second spring assembly triggered and driven) overturning of the earthing assembly. This can help to reduce or prevent accidental opening of the earthing switch due to e.g. external shocks or vibrations. The compressed spring force of the spring assembly for the earthing circuit can be used by the switching device to perform the earthing short circuit making operation. A separate spring system in the operating mechanism to drive the earthing switch via the main actuating shaft can therefore be eliminated.

[0031] Moreover, this arrangement also allows the entire load applied to the operating mechanism to be used to close the earthing switch, operating the earthing switch more efficiently. Moreover, the double toggle spring mechanism provides sufficient speed and contact pressure that the mechanism can be used for higher short circuit making operation current levels can be used, without the needed for an additional spring on the operating mechanism side.

[0032] In some implementations, during opening of the earthing switch, rotation of the transmission component causes the second spring assembly to compress. Optionally the second spring assembly and the one or more second linkages are configured such that, once the earthing assembly has rotated a predetermined amount in the first direction, the compressed second spring assembly is configured to urge the earthing assembly to rotate in the first direction about the third axis, the urging independent of the rotation of the transmission component.

[0033] This arrangement can provide a snapping action, with the one or more second linkages and the second spring assembly driving the earthing switch to open quickly, as well as ensuring isolation of the earthing switch from the earthing contacts of the device in the open position through the urging or biasing of the earthing switch towards the open position. This can help to reduce or prevent accidental closing of the earthing switch due to e.g. external shocks or vibrations.

[0034] In other words, the one or more second linkages and the second spring assembly can form a double toggle switch mechanism that provides a snapping action at both closing and opening operations of the earthing switch. In some implementations, the switching device further comprises one or more interlocks. Optionally, the one or more interlocks configured to prevent the operating mechanism from closing the vacuum interrupter before closing the disconnector switch. For example, an interlock can be provided between the actuating shaft and the disconnector assembly which prevents rotation of the shaft (in the first direction) around the axis unless the disconnector assembly has completed the necessary rotation about the second axis. Optionally, the one or more interlocks are configured to prevent the operating mechanism from opening the disconnector switch before opening the vacuum interrupter. For example, an interlock can be provided between the disconnector assembly and the cam which prevents rotation of the disconnector assembly (in the second direction) unless the cam is in the correct position. In this way, the device controls the operating sequence of the VI and disconnector switch and locks out any movement that would change the operating sequence.

[0035] The use of such interlocks acts to prevents the earth circuit from being closed before the VI and the disconnector are open. Moreover, the disconnector cannot be closed before the VI is in the correct position, and likewise, the disconnector cannot be opened until the VI is in the correct position. The interlocks can also prevent an earthing operation from being performed unless VI and disconnector are in the correct position, or vice versa. In some examples, the interlock positions can be displayed to a user / operator via one or more indicators on the operating mechanism.

[0036] In case the disconnector switch is in an incorrect position, the operating mechanism is blocked and the device cannot be electrically or manually activated. In this way, product line and operator safety will be ensured. Furthermore, in situations where the earthing switch is not in the correct position, the interlock(s) can mechanically prevent actuation of the operating mechanism; operator contact with the electrical circuits is therefore prevented in an energized state of the device, since opening of a door of the device can be prevented by the interlocks.

[0037] Also disclosed herein is a method of operating a switching device as described herein. The method comprises: rotating the actuating shaft in a first direction about the axis from a first position to a second position; in response, causing the operating mechanism to close the switching means, wherein the operating mechanism closes the disconnector switch before closing the vacuum interrupter; rotating the actuating shaft in a second direction about the axis from the second position to the first position; and in response, causing the operating mechanism to open the switching means, wherein the operating mechanism opens the vacuum interrupter before opening the disconnector switch.

[0038] In some implementations, the switching device comprises an earthing switch. Optionally, the method further comprises: rotating the actuating shaft in the second direction from the first position to a third position; and in response, causing the operating mechanism to close the earthing switch without actuating the switching means. In some implementations, the method further comprises: rotating the actuating shaft in the first direction from the third position to the first position; and in response, causing the operating mechanism to open the earthing switch without actuating the switching means.

[0039] Disclosed herein is a load break switchgear comprising a switching device as described herein. Disclosed herein is a vacuum circuit breaker comprising a switching device as described herein. The same switching device architecture can be used as a load break switchgear and a circuit breaker, without modification, provided an appropriate sized vacuum interrupter is used.

[0040] The features described above with respect to the switching device can be implemented as part of the method, and vice versa. Moreover, the features described above can be combined with one another in any suitable combination.

[0041] List of Figures

[0042] The detailed description is with reference to the following Figures:

[0043] Figure 1A shows an example switching device in a first, open, position;

[0044] Figure IB shows the switching device of Figure 1A in an earthed position;

[0045] Figure 1C illustrates the switching device of Figure 1A in a second, closed, position;

[0046] Figure ID illustrates a closing (making) sequence of the switching device, in which the switching device moves between the first (open) position of Figure 1A and the second, closed, position of Figure 1C;

[0047] Figure IE illustrates an opening (breaking) sequence of the switching device, in which the switching device moves between the second (closed) position of Figure 1C and the first position of Figure 1A;

[0048] Figure 2 is a schematic illustration of an example switching device, as described herein; Figure 3A is a side on view an example switching device in the first, open, position in which the disconnector switch is open and the vacuum interrupter is open, the device viewed from a first side;

[0049] Figure 3B is a side on view of the device of Figure 3A, the device viewed from a second side opposite the first side;

[0050] Figure 4A is a side on view the example switching device of Figure 3A in an intermediate position in which the disconnector switch is closed but the vacuum interrupter is open, the device viewed from the first side;

[0051] Figure 4B is a side on view of the device of Figure 4A, the device viewed from the second side;

[0052] Figure 5 is a side on view the example switching device of Figure 3A in the second, closed, position, in which the disconnector switch is closed and the vacuum interrupter is closed, the device viewed from the first side;

[0053] Figure 6A is a side on view the example switching device of Figure 3A in a third, earthed, position in which the disconnector switch is open and the vacuum interrupter is open but the earthing switch is closed, the device viewed from the first side;

[0054] Figure 6B is a side on view of the device of Figure 6A, the device viewed from the second side;

[0055] Figure 7 is a schematic block diagram illustrating example apparatus comprising a switching device as described herein; and

[0056] Figure 8 is a flowchart illustrating an example method of operating a switching device as described herein.

[0057] Detailed Description

[0058] Disclosed herein is a switching device and a method of operating the same.

[0059] With reference to Figures 1A to 1C, the switching device comprises a vacuum interrupter (or VI) 2 and a disconnector switch 3. The VI 2 and the disconnector 3 are connected in series. As shown, the VI 2 and disconnector can be electrically connected in series between first 1 and second 6 electrical terminals of the device (where the first and second terminals connect the device to a load and a supply, in any suitable arrangement). In this example, the device further comprises an optional earthing switch 4 and earthing contact terminal 5 (e.g. the fixed terminal 5 of the earthing contact). The fixed or stationary terminal or contact 5 can be T shaped to maximize dielectric distances. The device is actuated by an actuating shaft and operating mechanism (not shown). As shown in Figures 1A to 1C, the operating mechanism is configured such that the optional earthing switch can be opened and closed without opening and closing the VI 2 and disconnector 3. In other words, the VI 2 and disconnector switch 3 operate independently of the earthing switch 4. As seen by comparing the first, open, position of Figure 1A and the earthed position of Figure IB, the earthing switch 4 can be closed independently of the VI 2 and disconnector 3. As seen by comparing the first, open, position of Figure 1A and the second, closed, position of Figure 1C, the VI 2 and disconnector 3 can be closed independently of the earthing switch 4. The operating mechanism is thus configured to separate the movements of the VI, disconnector and earthing switch, enabling a safe operation of the device.

[0060] With further reference to Figures ID and IE, the VI 2 and the disconnector 3 are configured to open and close sequentially. In particular, when moving between the first position of Figure 1A and the second position of Figure 1C, the operating mechanism is configured such that the disconnector switch 3 is closed (Figure ID, Step-I) before closing the vacuum interrupter 2 (Figure ID, Step-II). Similarly, when moving between the second position of Figure 1C and the first position of Figure 1A, the operating mechanism is configured such that the vacuum interrupter 2 is opened (Figure IE, Step-I) before opening the disconnector switch 3 (Figure IE, Step-II). This is an automatic sequence, with both steps driven sequentially by a single operating means.

[0061] The vacuum interrupter and disconnector switch are thus connected in series and configured to work sequentially relative to each other, allowing the switching device to use the vacuum interrupter (or VI) for both opening and closing operations (e.g. the circuit breaking and circuit making happens within the VI 2). This enables the disconnector switch to be opened and closed at no load. Performing arc interruption and closing operations through a vacuum interrupter prevents contamination of the insulating medium, and can therefore enable safe operation of the switching device with a range of insulating mediums.

[0062] Arrangements in which the VI is used for both opening and closing (breaking and making) operations is stated as being disadvantageous in EP3614409A1, since the high thermal and electrodynamic stresses occurring during opening are dangerous for the contacts of the switch, as they may cause irreparable damage to the contacts. The lifetime of the VI can therefore be reduced. However, the present arrangement obviates these issues by the use of a vacuum tube which is capable of handling temporary discharges and short circuit currents that may occur. This arrangement reduces contact wear at the disconnector and prevents contamination of the insulating medium. The Vi's ability to interrupt a high number of nominal load currents allows the resulting design to also work as a circuit breaker. Moreover, the specifications of the vacuum interrupter can be modified or adapted depending on the desired application or implementation, providing flexibility and satisfying the demands for different short-circuit ratings or different voltage ratings in quick and simple manner.

[0063] The structure and operation of an example switching device is now discussed further with reference to the schematic of Figure 2.

[0064] Figure 2 shows a switching device 100 comprising switching means 104. The switching means comprises a vacuum interrupter 2 and a disconnector switch 3 connected in series. The switching device also comprises an operating mechanism 102 configured to open and close the switching means and an actuating shaft 21 configured to rotate about an axis 21a (arranged extending into the page) to actuate the operating mechanism 102. The operating mechanism 102 is coupled between the actuating shaft 21 and the switching means 104. The VI 2 and disconnector 3 are electrically connected in series and configured to be opened sequentially, as discussed with reference to Figures 1C, ID.

[0065] The actuating shaft is configured to rotate in a first direction 30 (here shown as a clockwise direction) about the axis 21a from a first position to a second position to cause the operating mechanism 102 to close the switching means 104, wherein the operating mechanism 102 is configured to close the disconnector switch 3 before closing the vacuum interrupter 2. The actuating shaft 21 is also configured to rotate in a second direction 31 (here shown as an anticlockwise direction) about the axis 21a from the second position to the first position to cause the operating mechanism 102 to open the switching means 104, wherein the operating mechanism is configured to open the vacuum interrupter 2 before opening the disconnector switch 3. Although shown with a particular orientation in Figure 2, the axis 21a and first and second directions 30, 31 may be provided in any suitable direction or orientation.

[0066] As discussed above, the VI and disconnector switch are operated sequentially by rotation of a single actuating shaft, without requiring further operator input; this simple architecture can allow the number of components to be reduced, thereby reducing assembly and manufacturing cost. Optionally, the switching device 100 further comprises an earthing switch 4 (denoted by the dashed lines). The operating mechanism 102 is further configured to open and close the earthing switch 4 without actuating the switching means 104. In this way, the earthing function is performed by the switching device, and is integrated into the structure of the device. The operating mechanism configuration separates the movements of the VI, disconnector and earthing switch, enabling a safe operation of the device. In this way, a 3-position product is provided with short circuit closing capability on a single shaft, allowing for the device 100 to be provided with a simple design and without a complex structure. Assembly and manufacturing costs of the device 100 may therefore be reduced.

[0067] The actuating shaft 21 is configured to rotate in the second direction 31 from the first position to a third position to cause the operating mechanism 102 to close the earthing switch 4. The actuating shaft 21 is also configured to rotate in the first direction 30 from the third position to the first position to cause the operating mechanism 102 to open the earthing switch 4. By integrating the earthing function into the structure of the switching device, and driving the different functions by the same, single, shaft that drives the VI and disconnector switch, operation of the device can be simplified. The number of parts can also be reduced, thereby reducing assembly and manufacturing cost.

[0068] The arrangement of the switching means 104 in the first, open, position is shown in Figure 1A and ID, Step-II (i.e. the VI 2 and the disconnector 3 are open, and the optional earthing switch 4 is also open). The arrangement of the switching means 104 in the second, closed, position is shown in Figure 1C, Step-II (i.e. the VI 2 and the disconnector 3 are closed, and the optional earthing switch 4 is open). The arrangement of the switching means 104 in the third, earthed, position is shown in Figure IB (i.e. the VI 2 and the disconnector 3 are open, and the optional earthing switch 4 is closed).

[0069] Some example implementations of the operating mechanism 102 are now discussed in more detail with reference to Figures 3A, 3B, 4A, 4B, 5, 6A and 6B. It will be understood that these implementations are provided as examples only, and that any suitable operating mechanism 102 can be used to implement the functionality of sequential operation of the VI 2 and disconnector 3 described herein. Moreover, the illustrated arrangement of the device 100 is an example only, and any suitable device configuration can be used to implement the desired functionality. With reference to Figure 3A and 3B, an example switching device 100 is shown in a first, open, position (in which the disconnector switch 3 is open and the vacuum interrupter 2 is open). The optional earthing switch 4 is also open.

[0070] The operating mechanism 102 is coupled between the actuating shaft 21 and the switching means 104 (comprising the disconnector switch 3 and the VI 2). The operating mechanism is also coupled between the actuating shaft 21 and the earthing switch 4.

[0071] In this example the operating mechanism 102 comprises a transmission component 15 rigidly coupled to the actuating shaft 21. Rotation of the transmission component in response to rotation of the shaft 21 drives the opening and closing of the disconnector switch 3 and the earthing switch 4. The operating mechanism further comprises a cam 9 rigidly coupled to the actuating shaft 21. Rotation of the cam in response to rotation of the shaft 21 drives the opening and closing of the vacuum interrupter 2.

[0072] In this example, the cam 9 and transmission component 15 are separate components, both rigidly coupled to the actuating shaft 21. By providing an arrangement in which actuation of the VI and disconnector switch is initiated by a single user input (rotation of the shaft 21, but then independently controlled by different mechanisms, operation of the switching device can be more easily fine-tuned. However, in other examples the cam and the transmission component can be integrally formed as a single component, the single component configured to facilitate the sequential operation of the VI and disconnector switch.

[0073] In more detail, the disconnector switch 3 comprises a disconnector assembly 7 configured to rotate about a second axis 7a. The disconnector assembly can cause the opening and closing of the disconnector switch. A moving contact of the switch 3 can be coupled to or mounted on the assembly 7. In particular, rotation of the transmission component drives the disconnector assembly to open and close the disconnector switch. To facilitate this transfer of the rotational force, the operating mechanism 102 further comprises one or more linkages 14 coupled between the transmission component 15 and the disconnector assembly 7, the one or more linkages 14 configured to cause rotation of the disconnector assembly 7 about the second axis 7a in response to rotation of the transmission component 15. Optionally, a spring assembly 11 is coupled to the disconnector assembly 7 on an opposite side of the second axis 7a to the linkage(s) 14. The earthing switch 4 comprises an earthing assembly 8 configured to rotate about a third axis 8a. The earthing assembly can cause the opening and closing of the earthing switch. A moving contact of the switch 4 can be coupled to or mounted on the assembly 8. In particular, rotation of the transmission component drives the earthing assembly 8 to open and close the earthing switch 4. To facilitate this transfer of the rotational force, the operating mechanism 102 further comprises one or more second linkages 13 coupled between the transmission component 15 and the earthing assembly 8, the one or more second linkages 13 configured to cause rotation of the earthing assembly 8 about the third axis 8a in response to rotation of the transmission component 15. Optionally, a second spring assembly 12 is coupled to the earthing assembly 8 on an opposite side of the third axis 8a to the linkage(s) 13.

[0074] The vacuum interrupter comprises a rod 10. The rod is configured to cause the opening and closing of the VI 2. The rod can be an insulated contact compression rod. In this example, the rod 10 comprises a cam follower 10a configured to engage with a cam surface 9a of the cam 9. Movement of the cam follower 10a in response to rotation of the cam 9 drives the opening and closing of the vacuum interrupter 2 via the rod 10.

[0075] With reference to Figures 4A, 4B, the device 100 is shown in an intermediate position (in which the disconnector switch 3 is closed but the vacuum interrupter is open. In Figure 5, the final movement of the device 100 has been completed and the device is in the second, closed, position (in which the disconnector switch 3 is closed and the vacuum interrupter 2 is closed). In both positions the optional earthing switch 4 is open. Transition from the first to the second position, i.e. closing of the device 100, will now be described in more detail.

[0076] The actuating shaft 21 is configured to rotate in a first direction (in this example a clockwise direction) about the axis in response to user input or actuation of the shaft 21. The shaft is rotated by a user from the first position to the second position to cause the operating mechanism 102 to close the switching means 104, wherein the operating mechanism 102 is configured to close the disconnector switch 3 before closing the vacuum interrupter 2.

[0077] To achieve this sequential closing of the switching means 104, the disconnector assembly 7 is configured to rotate in the first direction (clockwise) about the second axis 7a in response to rotation of the shaft and thus of the transmission component 15. The rotational movement is transferred to the disconnector assembly 7 through the linkage 14. The cam 9 is also configured to rotate in the first direction about the axis in response to rotation of the shaft. The linkage 14 first closes the movable contact 3 of the disconnector, then the cam 9 located on the actuating shaft 21 closes the vacuum interrupter 2. During the closing operation, the position of the VI 2 is maintained by the arrangement of the cam surface 9a, which is followed by the cam follower 10a as the cam 9 rotates.

[0078] Optionally, during closing of the disconnector switch 3, rotation of the transmission component 15 causes the spring assembly 11 of the disconnector assembly 7 to compress. In particular, the spring assembly 11 and the one or more linkages 14 are coupled at opposites sides of the second axis 7a. In this way, the spring 11 and linkage 14 are configured such that, once the disconnector assembly 7 has rotated a predetermined amount in the first direction (clockwise), the compressed spring assembly 11 is configured to urge the disconnector assembly 7 to rotate in the first direction about the second axis 7a, the urging independent of the rotation of the transmission component 15. This arrangement is shown in Figures 4A, 4B.

[0079] This arrangement can provide a snapping action, with the linkage 14 and the spring assembly 11 driving the disconnector switch 3 to close quickly, as well as ensuring good contact between the disconnector switch with electrical contact 23 of the device through the automatic (spring assembly triggered and driven) overturning of the disconnector assembly 7. This can help to reduce or prevent accidental opening of the disconnector switch due to e.g. external shocks or vibrations.

[0080] After the disconnector switch 3 is closed, rotation of the actuating shaft causes rotation of the cam. Due to this rotation, the cam surface 9a of the cam 9 pushes the rod 10 upwards at a specific, defined, instant, delivering contact pressure through the compression rod 10 and causing the VI 2 to close. This arrangement is shown in Figure 5. Once the VI 3 is closed, a current conduction path is completed between the second terminal 6, the disconnector switch 3 (comprising fixed contact 23 and a moving contact mounted on assembly 7, flexible conductor 19, the vacuum interrupter 2 and the first terminal 1.

[0081] During the closing operation, an operational interlock (not shown) allows the vacuum interrupter 2 to be closed only if the moving contact of the disconnector switch 3 is closed. For example, an interlock can be provided between the actuating shaft 21 and the disconnector assembly 7 which prevents rotation of the shaft 21 (in the first, clockwise, direction) around the axis 21a unless the disconnector assembly 7 has completed the necessary rotation about the second axis 7a. Therefore, even if a failure occurs in the operating mechanism, energization from the first terminal 1 or second terminal 6 is prevented when moving contact assembly 7 of the disconnector switch 3 is opened or interrupted. This can avoid arc generation at the disconnector switch 3 as a result of the incorrect energization or improper position of the circuit components.

[0082] The same operation occurs in reverse when the actuating shaft is rotated by a user from the second position to the first position, via the intermediate position of Figures 4A, 4B.

[0083] First, as the shaft 21 is rotated in the second (here anticlockwise) direction from the position in Figure 5, the cam 9 also rotates anticlockwise. The compression rod 10 follows the cam surface 9a and moves downward (to the position shown in Figure 4A, 4B). This opens the VI 2.

[0084] Next, as the shaft 21 continues to be rotated in the second (here anticlockwise) direction by the user, the corresponding rotation of the transmission component 15 causes the assembly 7 to rotate about the second axis 7a (via the transfer of force from the linkages 14). Slots in the linkages 14 allow for rotation of the cam 9 independently of the rotation of the assembly 7.

[0085] Optionally, as the assembly 7 is rotated by the linkage(s) 14, the spring assembly 11 is correspondingly compressed on the opposite side of the second axis 7a from the linkage(s) 14. The spring assembly 11 and the one or more linkages 14 are configured such that, once the disconnector assembly 7 has rotated a predetermined amount in the second direction, the compressed spring assembly 11 is configured to urge the disconnector assembly 7 to rotate in the second direction about the second axis 7a, the urging independent of the rotation of the transmission component 15.

[0086] This arrangement can provide a snapping action, with the one or more linkages and the spring assembly driving the disconnector switch to open quickly. The arrangement also ensures isolation of the disconnector switch from the electrical contacts 23 of the device in the open position through the urging or biasing of the disconnector switch towards the open position. This can help to reduce or prevent accidental closing of the disconnector switch due to e.g. external shocks or vibrations. Moreover, by providing a spring assembly which operates in two different directions, in both opening and closing, the operating mechanism described herein can form a double toggle switch mechanism that provides a snapping action at both closing and opening operations of the disconnector switch.

[0087] In the opening operation, a positional operational interlock (not shown) can allow rotation of the disconnector assembly 7 only if the cam 9 is in the correct position (i.e. the actuating shaft 21 is in the correct position). This ensures that the sequential operation and isolation of the disconnector switch 3 is maintained. Moreover, operator and line safety can be improved.

[0088] Appropriate energization and deactivation operations are carried out via the vacuum interrupter 2. Therefore, short circuit closing and nominal opening operations can be performed reliably at low speeds with proven vacuum interrupter technology. Therefore, the mechanical life of the disconnector switch is preserved.

[0089] Operation of the earthing switch will now be discussed with reference to Figures 3A, 3B and Figures 6A, 6B, which shows the device 100 in a third, earthed position in which the switching means 104 are open but the earthing switch 4 is closed.

[0090] The actuating shaft 21 is configured to rotate in the second direction (in this example an anticlockwise direction) about the axis in response to user input or actuation of the shaft 21. The shaft is rotated by a user from the first position to the third position to cause the operating mechanism 102 to close the earthing switch 4. During closing of the earthing switch 4, the earthing assembly 8 is configured to rotate in the second direction about the third axis 8a in response to rotation of the shaft, and thus of the transmission component 15. The rotational movement is transferred to the earthing assembly 8 through the second linkage(s) 13.

[0091] Optionally, during closing of the earthing switch 4, rotation of the transmission component 15 causes the second spring assembly 12 of the earthing assembly 8 to compress. In particular, the second spring assembly 12 and the one or more linkages 13 are coupled at opposites sides of the third axis 8a. In this way, the second spring assembly 12 and the one or more second linkages 13 are configured such that, once the earthing assembly 8 has rotated a predetermined amount in the second direction 31, the compressed second spring assembly 12 is configured to urge the earthing assembly 8 to rotate in the second direction 31 about the third axis 8a, the urging independent of the rotation of the transmission component 15. In this way, the closing of the earthing switch 4 can be driven by the spring assembly 12 on the earthing assembly 8. Driving with the spring assembly can be beneficial during the closing operation since the earthing fault making operation requires a high speed and torque under high magnetic forces.

[0092] This spring assembly 12 arrangement can provide a snapping action, with the one or more second linkages 13 and the second spring assembly driving the earthing switch to close quickly, as well as ensuring good contact between the earthing switch with earthing contacts of the device through the automatic (second spring assembly triggered and driven) overturning of the earthing assembly. This can also help to reduce or prevent accidental opening of the earthing switch due to e.g. external shocks or vibrations.

[0093] During earthing, the VI 2 does not receive any driving force from the cam 9 and therefore its open position is maintained by the rod 10. The contact pressure spring assembly 12 of the earth circuit provides contact pressure, resulting in rigidity in case of a short circuit.

[0094] Once the earthing switch 4 is closed, a current conduction path is completed between the second terminal 6, the earthing switch 4 (comprising fixed contact 22 and a moving contact mounted on assembly 8, flexible conductor 16, and the fixed terminal 5 of the earth circuit. In this way, the current is transferred to the earth by following the conduction path. The flexible conductor 16 can be a flexible circuit flex 16. The use of such a circuit flex connection between the fixed terminal 5 of the earth circuit and the moving contact of the earthing switch 4 can reduce the amount of copper needed, and also enhance the dielectric performance. The use of a circuit flex 16 connected to the stationary or fixed earth terminal 5, which is positioned at a possible maximum distance from the earthing switch 4, together with an optimum size moving earth contact, can maximize the dielectric distances and improve dielectric performance.

[0095] The same operation occurs in reverse when the actuating shaft is rotated by a user from the third position to the first position. Optionally, during opening of the earthing switch 4, rotation of the transmission component 15 causes the second spring assembly 12 to compress. The second spring assembly 12 and the one or more second linkages 13 are configured such that, once the earthing assembly 8 has rotated a predetermined amount in the first direction 30, the compressed second spring assembly 12 is configured to urge the earthing assembly 8 to rotate in the first direction 30 about the third axis 8a, the urging independent of the rotation of the transmission component 15. In this way, the spring assembly mechanism 12 is active also during the opening operation (e.g. acts as a double spring toggle mechanism).

[0096] This arrangement can provide a snapping action, with the one or more second linkages and the second spring assembly driving the earthing switch to open quickly, as well as ensuring isolation of the earthing switch from the earthing contacts of the device in the open position through the urging or biasing of the earthing switch towards the open position. This can help to reduce or prevent accidental closing of the earthing switch due to e.g. external shocks or vibrations. In other words, the one or more second linkages and the second spring assembly can form a double toggle switch mechanism that provides a snapping action at both closing and opening operations of the earthing switch.

[0097] The operating mechanism 102 works in such a way that the rotation of the moving contact assembly 7 of the disconnector switch 3 for closing and opening operations does not affect the moving contact assembly 8 of the earthing switch 4, or vice versa. Any suitable operating mechanism 102 can be used, in addition to the examples described herein. Mechanism geometries can be designed to meet the mechanical and magnetic forces arising during opening and closing operations for a given application.

[0098] One or more interlocks can be used to provide axial locking, providing positional control between the actuating shaft 21 and the earthing switch 4 and / or disconnector switch 3, allowing closing and opening only when the components are in the correct position. In other words, there is an interlock between the main and earthing circuits. Unless the main circuit is in the first position (a neutral position), the earthing function cannot be operated, and vice versa. For example, the shaft 21 can only be rotated to the third and / or second positions when the moving contacts of the earthing switch 4 and / or disconnector switch 3 are in full contact with the fixed contacts 22 and / or 23. Therefore, if there is a failure, the actuating shaft will be in an incorrect position and the user or operator will know that the shaft 21 is in the wrong position and so be prevented from accessing the device 100 whilst it is live. The fixed or stationary contacts 22, 23 can be T shaped contacts to help maximize dielectric distances.

[0099] Since the positional interlocks depend only on movements transmitted by the actuating shaft, the optional spring assemblies 11, 12 described herein can provide additional benefits during operation of the disconnector switch and / or earthing switch. The forces exerted by the spring assemblies can facilitate both automatic triggering (opening) and closing moments, maintain isolation / separation distances and provide rigidity during short circuit current withstand operations. The spring assemblies can be formed of any suitable resiliently deformable member, which is resilient by form and / or material. Optionally the spring assemblies comprise a spring, optionally a compression spring.

[0100] With further reference to Figures 3A-6B, the device may optionally include an electrical lower fixed terminal field regulator 17, a rod field regulator 18 and a main circuit flexible field regulator 20 in order to enhance the dielectric performance of the vacuum interrupter 2. In the first, closed, position, the lower fixed terminal field regulator 17 and the main circuit flexible field regulator 20 provide homogeneous electrical fields by means of their geometries, and potential flashovers are prevented for both clearance points and other phases. The rod field regulator 18 masks the live electrical fields of both the vacuum interrupter 2 and the isolated contact pressure rod 10 when the vacuum interrupter 2 is in both open and closed positions. Because of its cylindrical form, the electrical field level of the vacuum interrupter 2 is reduced. For similar reasons, the electrical field intensity arising around the earth fixed contact 22 and the disconnector fixed contact 23 becomes equipotential and homogeneous through the geometry and external insulation of the fixed contacts. With these developed shielding and electrical field solutions, long-term corona discharges are prevented, thus toxic gases and environmental effects are eliminated.

[0101] With reference to Figure 7, a switching device 100 as described herein can be implemented in a range of different apparatus, systems or products. In one example, the device 100 is implemented as part of a load break switchgear, LBS, 702. In another example, the device 100 is implemented as part of a vacuum circuit breaker, VCB, 704. According to the desired application, different VI specifications can be used without any structural modifications to the rest of the switching device. The switching device architecture is thus adapted in terms of both dielectric and mechanical structure for LBS and VCB solutions.

[0102] With reference to Figure 8, an example method of operating a switching device as described herein is provided.

[0103] The method comprises rotating 802 the actuating shaft in a first direction about the axis from a first position to a second position and, in response, causing 804 the operating mechanism to close the switching means, wherein the operating mechanism closes the disconnector switch before closing the vacuum interrupter. The method also comprises rotating 806 the actuating shaft in a second direction about the axis from the second position to the first position and, in response, causing 808 the operating mechanism to open the switching means, wherein the operating mechanism opens the vacuum interrupter before opening the disconnector switch. After operation 808, the method can return to operation 802.

[0104] Alternatively, the method can continue to optional steps of operating the earthing switch 4. Optionally, the method further comprises rotating 810 the actuating shaft in the second direction from the first position to a third position and, in response, causing 812 the operating mechanism to close the earthing switch without actuating the switching means. Optionally, the method further comprises rotating 814 the actuating shaft in the first direction from the third position to the first position and, in response, causing 816 the operating mechanism to open the earthing switch without actuating the switching means. After operation 816, the method can return to operation 810. Alternatively, the method can return to operation 802.

Claims

- 23 -Claims1. A switching device (100), comprising: switching means (104) comprising a vacuum interrupter (2) and a disconnector switch (3) connected in series; an operating mechanism (102) configured to open and close the switching means; and an actuating shaft (21) configured to rotate about an axis (21a) to actuate the operating mechanism (102), wherein : the actuating shaft (21) is configured to rotate in a first direction (30) about the axis (21a) from a first position to a second position to cause the operating mechanism (102) to close the switching means (104), wherein the operating mechanism (102) is configured to close the disconnector switch (3) before closing the vacuum interrupter (2), and the actuating shaft (21) is configured to rotate in a second direction (31) about the axis (21a) from the second position to the first position to cause the operating mechanism (102) to open the switching means (104), wherein the operating mechanism is configured to open the vacuum interrupter (2) before opening the disconnector switch (3).

2. The switching device (100) of claim 1, further comprising an earthing switch (4), wherein the operating mechanism (102) is further configured to open and close the earthing switch (4) without actuating the switching means (104).

3. The switching device (100) of claim 2, wherein : the actuating shaft (21) is configured to rotate in the second direction (31) from the first position to a third position to cause the operating mechanism (102) to close the earthing switch (4), and the actuating shaft (21) is configured to rotate in the first direction (30) from the third position to the first position to cause the operating mechanism (102) to open the earthing switch (4).

4. The switching device (100) of any preceding claim, wherein the operating mechanism (102) comprises a transmission component (15) rigidly coupled to the actuating shaft (21), wherein rotation of the transmission component drives the opening and closing of the disconnector switch (3).

5. The switching device (100) of claim 4, wherein the disconnector switch (3) comprises a disconnector assembly (7) configured to rotate about a second axis (7a), the operating mechanism (102) further comprising one or more linkages (14) coupled between the transmission component (15) and the disconnector assembly (7), the one or more linkages (14) configured to cause rotation of the disconnector assembly (7) about the second axis (7a) in response to rotation of the transmission component (15).

6. The switching device (100) of claim 5, wherein : during closing of the disconnector switch (3), the disconnector assembly (7) is configured to rotate in the first direction (30) about the second axis (7a), and during opening of the disconnector switch (3), the disconnector assembly (7) is configured to rotate in the second direction (31) about the second axis (7a).

7. The switching device (100) of claim 6, wherein the disconnector switch (3) further comprises a spring assembly (11), wherein : during closing of the disconnector switch (3), rotation of the transmission component (15) causes the spring assembly (11) to compress, and the spring assembly (11) and the one or more linkages (14) are configured such that, once the disconnector assembly (7) has rotated a predetermined amount in the first direction (30), the compressed spring assembly (11) is configured to urge the disconnector assembly (7) to rotate in the first direction (30) about the second axis (7a), the urging independent of the rotation of the transmission component (15).

8. The switching device (100) of any of claims 4 to 7, wherein the operating mechanism comprises a cam (9) rigidly coupled to the actuating shaft (21), the cam configured to drive opening and closing of the vacuum interrupter (2), optionally, wherein the cam and the transmission component are integrally formed as a single component.

9. The switching device (100) of claim 8, wherein the vacuum interrupter (2) comprises a rod (10), the rod (10) comprising a cam follower (10a) configured to engage with a cam surface (9a) of the cam (9), and wherein movement of the cam follower (10a) in response to rotation of the cam (9) drives the opening and closing of the vacuum interrupter (2) via the rod (10).

10. The switching device of any of claims 4 to 9, wherein rotation of the transmission component (15) further drives the opening and closing of the earthing switch (4).

11. The switching device (100) of claim 10, wherein the earthing switch (4) comprises an earthing assembly (8) configured to rotate about a third axis (8a), the operating mechanism (102) further comprising one or more second linkages (13) coupled between the transmission component (15) and the earthing assembly (8), the one or more second linkages (13) configured to cause rotation of the earthing assembly (8) about the second axis (8a) in response to rotation of the transmission component (15).

12. The switching device (100) of claim 11, wherein : during closing of the earthing switch (4), the earthing assembly (8) is configured to rotate in the second direction (31) about the third axis (8a), and during opening of the earthing switch (4), the earthing assembly (8) is configured to rotate in the first direction (30) about the third axis (8a).

13. The switching device (100) of claim 12, wherein the earthing switch (4) further comprises a second spring assembly (12), wherein: during closing of the earthing switch (4), rotation of the transmission component (15) causes the second spring assembly (12) to compress, and the second spring assembly (12) and the one or more second linkages (13) are configured such that, once the earthing assembly (8) has rotated a predetermined amount in the second direction (31), the compressed second spring assembly (12) is configured to urge the earthing assembly (8) to rotate in the second direction (31) about the third axis (8a), the urging independent of the rotation of the transmission component (15)..

14. The switching device (100) of any preceding claim, further comprising one or more interlocks, the one or more interlocks configured to: prevent the operating mechanism (102) from closing the vacuum interrupter(2) before closing the disconnector switch (3); and / or prevent the operating mechanism from opening the disconnector switch(3) before opening the vacuum interrupter (2).

15. A method of operating a switching device in accordance with any preceding claim, the method comprising:- 26 - rotating (802) the actuating shaft in a first direction (30) about the axis (21a) from a first position to a second position; in response, causing (804) the operating mechanism (102) to close the switching means (104), wherein the operating mechanism (102) closes the disconnector switch (3) before closing the vacuum interrupter (2); rotating (806) the actuating shaft (21) in a second direction (31) about the axis (21a) from the second position to the first position; and in response, causing (808) the operating mechanism (102) to open the switching means (104), wherein the operating mechanism opens the vacuum interrupter (2) before opening the disconnector switch (3).

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