Mechanical actuation mechanism for medium-voltage switchgear

Abstract

Mechanical actuation mechanism for medium-voltage switchgear A medium voltage switchgear comprises: a three position changeover switch, COS, having COS contacts that are moveable between a service position, a neutral position and an earth position; a vacuum interrupter, VI, having VI contacts that are moveable between an open position and a closed position; and a mechanical actuation mechanism for manually operating the COS and the VI. The mechanical actuation mechanism is configured such that: when the COS contacts are moved from the service position to the neutral position, the mechanical actuation mechanism causes the VI contacts to be moved into the open position before the COS contacts leave the service position.

Description

[0001] Mechanical actuation mechanism for medium-voltage switchgear

[0002] Field of Invention

[0003] The field of the present disclosure is actuation mechanisms for switchgear devices. In particular, the disclosure relates to a mechanical actuation mechanism for simultaneously operating a three-position changeover switch and a vacuum interrupter for a medium-voltage switchgear.

[0004] Background

[0005] In a two-position switchgear device, a changeover switch is moved between a service position and an earth position. It is known to provide a circuit breaker or load break switch in series with the two-position changeover switch. In known systems of this form, the changeover switch is operated independently from the circuit breaker or load break switch.

[0006] Incorrect operation of the changeover switch or circuit breaker may result in fault such as contact arcing at the changeover switch contacts. The likelihood of such problems is increased when a three-position changeover switch is used, where there is a greater ambiguity around the state of the switch at any one time.

[0007] In view of the above, there is a need for improved actuating mechanisms for three- position switchgear devices that allow simple and unambiguous operation.

[0008] Summary of Invention

[0009] In a first aspect of the disclosure, a medium-voltage switchgear is provided. The medium voltage switchgear comprises: a three position changeover switch, COS, having COS contacts that are moveable between a service position, a neutral position and an earth position; a vacuum interrupter, VI, having VI contacts that are moveable between an open position and a closed position; and a mechanical actuation mechanism for manually operating the COS and the VI. The mechanical actuation mechanism is configured such that: when the COS contacts are moved from the service position to the neutral position, the mechanical actuation mechanism causes the VI contacts to be moved into the open position before the COS contacts leave the service position.

[0010] By providing a mechanical actuation mechanism that is can simultaneously control both a vacuum interrupter and a changeover switch, simple and unambiguous switching operations can be performed when changing between states in a switchgear comprising a three-position changeover switch.

[0011] In some examples, the mechanical actuation mechanism is configured to provide one or more of the following operations: when the COS contacts are moved from the neutral position to the earth position, the mechanical actuation mechanism causes the VI contacts to be moved into the closed position after the COS contacts reach the earth position; when the COS contacts are moved from the earth position to the neutral position, the mechanical actuation mechanism causes the VI contacts to be moved into the open position before the COS contacts leave the earth position; when the COS contacts are moved from the neutral position to the service position, the mechanical actuation mechanism causes the VI contacts to be moved into the closed position after the COS contacts reach the service position.

[0012] In some examples, the medium-voltage switchgear further comprises a service gate and an earth gate. The mechanical actuation mechanism is configured such that: mechanical actuation of a first coupling disposed within the service gate causes movement of the COS contacts between the service position and the neutral position; and mechanical actuation of a second coupling disposed within the earth gate causes movement of the COS contacts between the earth position and the neutral position.

[0013] In some examples, the medium-voltage switchgear further comprises a gate selection mechanism configured such that only one of the service gate and the earth gate can be opened at one time.

[0014] In some examples, the first coupling is configured to be mechanically actuated by rotating a handle inserted into the service gate, and the second coupling is configured to be mechanically actuated by rotating the handle when inserted into the earth gate.

[0015] In some examples, mechanical actuation of the first coupling in a first direction causes: movement of the COS contacts from the service position to neutral position, and actuation of a trip shaft leading to opening of the VI contacts before the COS contacts leave the service position; and mechanical actuation of the first coupling in a second direction causes: movement of the COS contacts from the neutral position to the service position; and driving of a VI shaft to load a spring buffer, causing closing of the VI contacts at the end of the range motion, after the COS contacts have arrived at the service position. In some examples, mechanical actuation of the second coupling in the second direction causes: movement of the COS contacts from the neutral position to the earth position ; and driving of the VI shaft to load the spring buffer, causing closing of the VI contacts at the end of the range motion, after the COS contacts have arrived at the earth position, and mechanical actuation of the second coupling in the first direction causes: movement of the COS contacts from the earth position to the neutral position; and actuation of the trip shaft leading to opening of the VI contacts before the COS contacts leave the earth position.

[0016] In some examples, the mechanical actuation mechanism comprises a third coupling and a fifth coupling. The third coupling is a unidirectional coupling that is driven when the first coupling is rotated in the first direction and idles when the first coupling is rotated in the second direction. The fifth coupling is a unidirectional coupling that is driven when the first coupling is rotated in the second direction and idles when the first coupling is rotated in the second direction.

[0017] In some examples, when the first coupling rotates in the first direction, the third coupling drives the trip shaft leading to opening of the VI contacts; and when the first coupling rotates in the second direction, the fifth coupling drives the VI shaft causing closing of the VI contacts.

[0018] In some examples, the third coupling comprises a first ratchet-key, wherein the first ratchet-key is configured to be actuated by a second protrusion of a handle used to mechanically actuate the first coupling when the first coupling is rotated in the first direction, and wherein the first ratchet-key allows the second protrusion to pass when the handle is rotated in the second direction.

[0019] In some examples, the mechanical actuation mechanism comprises a fourth coupling. The fourth coupling is a unidirectional coupling that is driven when the second coupling is rotated in the first direction and idles when the second coupling is rotated in the second direction. The fifth coupling is driven when the second coupling is rotated in the first direction and idles when the second coupling is rotated in the second direction.

[0020] In some examples, when the second coupling rotates in the first direction, the fourth coupling drives the trip shaft leading to opening of the VI contacts; and when the second coupling rotates in the second direction, the fifth coupling drives the VI shaft causing closing of the VI contacts. In some examples, the fourth coupling comprises a second ratchet-key. The second ratchet-key is actuated by a second protrusion of a handle used to mechanically actuate the second coupling when the second coupling s rotated in the first direction. The second ratchet-key allows the second protrusion to pass when the handle is rotated in the second direction.

[0021] In some examples, the first coupling comprises a first gear wheel and a first shaft that can rotate freely with respect to each other when they are not engaged by a handle. The first gear wheel and the first shaft comprise openings configured such that insertion of a first protrusion of the handle into the openings causes the first gear wheel and the first shaft to be rotationally coupled to each other.

[0022] In another aspect of the disclosure, a method of operating a medium-voltage switchgear is provided. The method comprises at least one of: inserting a handle into a service gate and rotating the handle to drive a first coupling; or inserting the handle into the earth gate and rotating the handle to drive the second coupling.

[0023] Brief Description of the Figures

[0024] The detailed description is with reference to the following figures.

[0025] Fig. 1 schematically illustrates relationships between elements of a switchgear device comprising a mechanical actuation mechanism when operated from a service gate in accordance with embodiments of the disclosure;

[0026] Fig. 2 schematically illustrates relationships between elements of a switchgear device comprising a mechanical actuation mechanism when operated from an earth gate in accordance with embodiments of the disclosure;

[0027] Fig. 3 schematically illustrates relationships between elements of a switchgear device comprising a mechanical actuation mechanism when operated by an electrical motor in accordance with embodiments of the disclosure;

[0028] Fig 4 illustrates an example of a coupling mechanism between a handle, a gear wheel and a shaft in examples of the disclosure; Fig. 5 illustrates an example of a unidirectional coupling mechanism in accordance with an example of the disclosure;

[0029] Fig. 6 illustrates another example of a unidirectional coupling mechanism in accordance with an example of the disclosure;

[0030] Fig. 7 illustrates an example of couplings and transmissions between elements of a mechanical actuation mechanism in examples of the disclosure;

[0031] Fig. 8 schematically illustrates an arrangement of part of a power supply network comprising a switchgear in accordance with examples of the disclosure.

[0032] Detailed Description

[0033] The present disclosure provides a medium-voltage switchgear device comprising a three-position changeover switch, COS, and a vacuum interrupter switch, VI. Electrical contacts of the COS (or "COS contacts") are moveable between a service position, a neutral position, and a ground position. The neutral position is an intermediate position between the service position and the earth position. The VI and the COS are disposed in series in a current path of the switchgear device such that opening of the VI contacts or the COS contacts interrupts current the current flow path through the switchgear device. The switchgear further comprises a mechanical actuation mechanism. Operation of the mechanical actuation mechanism provides simultaneous control of the COS and the VI. The mechanical actuation mechanism comprises one or more couplings capable of receiving a mechanical input, such as the rotation of a handle by a user, where the one or more couplings are mechanically coupled to both the COS and the VI, allowing simultaneous mechanical control of the COS and the VI through the mechanical input. In particular, operations of the mechanical actuation mechanism cause operation of the COS and VI in sequence such that the electrical contacts of the VI (or "VI contacts") are opened prior to the COS contacts leaving either the service position or the earth position when the COS is moved from the service position or the earth position to the neutral position. Further operations of the mechanical actuation mechanism cause operation of the COS and VI in sequence such that VI contacts are closed subsequent to the COS contacts reaching the service position or the earth position when the COS is moved from the neutral position to the service position or the earth position.

[0034] The mechanical actuation mechanism is configured to perform four distinct operations: In a first operation, the COS contacts are moved from the service position to the neutral position. Prior to the COS contacts leaving the service position, the VI contacts are opened.

[0035] In a second operation, the COS contacts are moved from the neutral position to the earth position. Subsequent to the COS contacts reaching the earth position, the VI contacts are closed.

[0036] In a third operation, the COS contacts are moved from the earth position to the neutral position. Prior to the COS contacts leaving the earth position, the VI contacts are opened.

[0037] In a fourth operation, the COS contacts are moved from the neutral position to the service position. Subsequent to the COS contacts reaching the service position, the VI contacts are closed.

[0038] In embodiments of the disclosure, a user may mechanically actuate a first coupling or a second coupling mechanical actuation mechanism in order to operate the switchgear device. The first and second couplings can be respectively actuated by a user by insertion of a handle into the first or second couplings and rotation the handle. Both of the first coupling and the second coupling can be actuated in a first direction or a second direction. The first and second directions may be clockwise and anticlockwise, or vice versa. The first coupling and the second coupling are respectively coupled to other elements of the switchgear via unidirectional couplings that are driven in one direction and idle in the opposite direction. Operation of the first and second couplings of the mechanical actuation device respectively cause mechanical coupling of different components of the mechanical actuation device. The use of first and second couplings and unidirectional switchgear devices allows the four operations of the mechanical actuation mechanism to be provided by actuation of the first and second couplings in the first and second directions. That is, distinct operations are provided by i) actuation of the first coupling in the first direction, ii) actuation of the first coupling in the second direction, iii) actuation of the second coupling in the first direction, and iv) actuation of the second coupling in the second direction.

[0039] The switchgear device comprises a service gate and an earth gate. The first coupling is mechanically actuated by inserting the handle into the service gate and rotating the handle in the first or second direction. The second coupling is mechanically actuated by inserting the handle into the earth gate and rotating the handle in the first or second direction. The same handle may be used to operate both the service gate and the earth gate. The handle may be a removeable handle that is configured to couple with both the first and second couplings such that the handle may be inserted into the first or second gate by a user and rotated by the user to transmit torque to the first or second coupling and cause rotation of the first or the second coupling. The service gate and the earth gate are configured such that only one of the two gates can be accessed at any one time. This may be achieved using a gate selector in combination with interlocks to manage which gate is accessed. Alternatively, a sliding panel may be moveable between a position where it covers the earth gate and a position where it covers the service gate.

[0040] In order to move the switchgear from a first state in which the COS contacts are in the service position to a second state in which the COS contacts are in the earth position, the user may perform the first and second operations sequentially. That is, the user first inserts the handle into the service gate and rotates the first coupling in a first direction by rotating the handle in the first direction in order to perform the first operation. The user then removes the handle from the service gate and inserts the handle into the earth gate. The user rotates second coupling in the second direction by rotating the handle in the second direction to perform the second operation.

[0041] In order to move the switchgear from the second state in which the COS contacts are in the earth position to the first state in which the COS contacts are in the service position, the user may perform the third and fourth operations sequentially. That is, the user first inserts the handle into the earth gate and rotates the second coupling in a first direction by rotating the handle in the first direction in order to perform the third operation. The user then removes the handle from the earth gate and inserts the handle into the service gate. The user rotates first coupling by rotating the handle in the second direction in order to perform the fourth operation.

[0042] Figs. 1, 2 and 3 provides schematic depictions of couplings and transmissions of the mechanical actuation mechanism when operated by the service gate, the earth gate and by a motor, respectively. First coupling Cl and second coupling C2 are activated depending on whether the handle is inserted into the coupling. Third coupling C3, fourth coupling C4, fifth coupling C5 and sixth coupling C6 are unidirectional couplings that can be driven in one direction and that idle in the opposite direction. First transmission TM1, second transmission TM2, third transmission TM3, fourth transmission TM4, fifth transmission TM5 and sixth transmission TM6 are activated depending on the configuration of the device. Electrical motor Ml is provided to activate the VI remotely.

[0043] Fig. 1 illustrates an example in which the service gate is open and the handle is inserted in the service gate. Insertion of the handle into the service gate activates the first coupling Cl. An example of a suitable mechanism for the first coupling Cl is described with reference to Figs. 4 and 7. Rotation of the first coupling Cl causes rotation of a COS shaft on which the COS contacts are mounted via the fifth transmission TM5. The fifth transmission TM5 is described in more detail with reference to Fig. 7.

[0044] Rotation of the first coupling Cl in a first direction causes the COS contacts to move from the service position to the neutral position via rotation of the COS shaft. Rotation of the first coupling Cl in the second direction causes the COS contacts to move from the neutral position to the service position via rotation of the COS shaft.

[0045] The unidirectional third coupling C3 is described in more detail with reference to Fig. 5. Third coupling C3 is driven when the first coupling Cl is rotated in the first direction and idles when the first coupling Cl is rotated in the second direction. Third coupling C3 drives a trip shaft by the second transmission TM2 when the first coupling Cl is rotated in the first direction. Actuation of the trip shaft causes the VI contacts to open. The mechanical actuation mechanism is configured such that the VI contacts open prior to the COS contacts leaving the service position when the first coupling Cl is rotated in the first direction.

[0046] The unidirectional fifth coupling C5 is driven when the first coupling Cl is rotated in the second direction and idles when the first coupling Cl is rotated in the first direction. The fifth coupling C5 causes a VI shaft to be driven when the first coupling Cl is rotated in the second direction. Driving of the VI shaft loads a spring buffer, causing the VI contacts to be closed. The mechanical actuation mechanism is configured such that the spring buffer causes the VI contacts to close subsequent to the COS contacts reaching the service position when the first coupling Cl is rotated in the second direction.

[0047] Fig. 2 illustrates an example in which the earth gate is open and the handle is inserted in the earth gate. Insertion of the handle into the earth gate activates the second coupling C2. The second coupling C2 is described in more detail with reference to Figs. 4 and 7. Rotation of the second coupling C2 causes rotation of the COS shaft on which the COS contacts are mounted via the sixth transmission TM6. The sixth transmission TM6 is described in more detail with reference to Fig. 7.

[0048] Rotation of the second coupling C2 in a first direction causes the COS contacts to move from the earth position to the neutral position via rotation of the COS shaft. Rotation of the second coupling C2 in the second direction causes the COS contacts to move from the neutral position to the earth position via rotation of the COS shaft.

[0049] The unidirectional fourth coupling C4 is driven when the second coupling C2 is rotated in the first direction and idles when the second coupling C2 is rotated in the second direction. The fourth coupling C4 causes the trip shaft to be driven via the third transmission TM3 when the second coupling C2 is rotated in the first direction. Actuation of the trip shaft causes the VI contacts to open. The mechanical actuation mechanism is configured such that the VI contacts open prior to the COS contacts leaving the earth position when the second coupling C2 is rotated in the first direction.

[0050] Rotation of the second coupling is transmitted to the unidirectional fifth coupling C5 via the first transmission TM1. The fifth coupling C5 is driven when the second coupling C2 is rotated in the second direction and idles when the second coupling C2 is rotated in the first direction. The fifth coupling C5 causes the VI shaft to be driven when the second coupling C2 is rotated in the second direction. Driving of the VI shaft loads a spring buffer, causing the VI contacts to be closed. The mechanical actuation mechanism is configured such that the spring buffer causes the VI contacts to close subsequent to the COS contacts reaching the earth position when the second coupling C2 is rotated in the second direction.

[0051] Fig. 3 illustrates an example in which the handle is not inserted in the earth gate or the service gate and the VI shaft is rotated by the electrical motor Ml through sixth coupling C6 for closing the contacts of the VI remotely. In this situation, the COS shaft cannot be operated. The VI contacts can be opened by the trip device. The electrical motor Ml and the trip device are operated via remote signals.

[0052] Fig. 4 illustrates an example of a coupling mechanism suitable for use in the first coupling Cl and the second coupling C2. In this example, a handle 40 comprises a protrusion 41 extending axially from the end of the main body of the handle 40. A first gear wheel 42 is able to rotate freely with respect to a first shaft 43 when the handle is not engaged. The first gear wheel 42 and the first shaft 43 both comprise openings 44 that, when aligned, allow a first protrusion 41 of the handle 40 to be received into the combined opening 44. Thus, inserting the first protrusion 41 of the handle 40 into the opening 44 causes the first gear wheel 42 to be rotationally coupled to the first shaft 43. In the example illustrated in Fig. 4, the protrusion 41 is formed as an elongate tab or blade and the combined opening 44 is formed as a slot configured to receive the elongate tab or blade. The openings 44 in the first gear wheel 42 and the first shaft are shaped such that they are only able to receive the first protrusion 41 when they are aligned, thereby forcing to first shaft 43 and the first gear wheel 42 to corotate when the first protrusion 41 is inserted into the combined opening 44.

[0053] Fig. 5 illustrates an example of the third coupling C3 in the form of a first ratchet-key 51. The first ratchet-key 51 is able to rotate around a pivot point 52 in a first direction from a neutral position but cannot rotate in a second direction from the neutral position. The handle 40 has one or more second protrusions 45 extending radially from the main body of the handle 40. When the handle 40 is rotated in the first direction, the second protrusions 45 exert a force on the first ratchet-key 51. The force on the first ratchet-key 51 is transferred through a slider 54 to the trip shaft 55. When the handle 40 is rotated in the second direction, the first ratchet-key is able to rotate around pivot point 52 to allow the second protrusions 45 to pass freely.

[0054] Fig. 6 illustrates an example of the fourth coupling C4 the form of a second ratchetkey 56. Second ratchet-key 56 is able to rotate around a pivot point 57 in a first direction from a neutral position but cannot rotate in a second direction from the neutral position. When the handle 40 is rotated in the first direction, the second protrusions 45 exert a force on the second ratchet-key 56. The force on the second ratchet-key 56 is transferred through the slider 54 to the trip shaft 55. When the handle 40 is rotated in the second direction, the second ratchet-key is able to rotate around pivot point 57 to allow the second protrusions 45 to pass freely. The first and second ratchet-keys may be mounted on a shared slider 54.

[0055] As third coupling C3 and fourth coupling C4 require insertion of the handle 40 in the service gate or the earth gate respectively, only one of the third coupling C3 and the fourth coupling C4 can be activated at one time. Inserting the handle 40 in the service gate activates third coupling C3 and inserting the handle 40 in the service gate activates fourth coupling C4.

[0056] Fig. 7 illustrates the first transmission TM1, the fifth transmission TM5 and the sixth transmission TM6. The first coupling Cl comprises a first gear wheel 42a and a first shaft 43a. The second coupling C2 comprises a second gear wheel 42b and a second shaft 43b.

[0057] The first gear wheel 42a is able to rotate freely with respect to the first shaft 43a when no handle is inserted in the service gate, and the first gear wheel 42a and the first shaft 43a are rotationally coupled when the handle is inserted in the service gate.

[0058] The second gear wheel 42b is able to rotate freely with respect to the second shaft 43b when no handle is inserted in the earth gate, and the second gear wheel 42b and the second shaft 43b are rotationally coupled when the handle is inserted in the earth gate.

[0059] The first shaft 43a and the second shaft 43b are always coupled by the first transmission TM1, which comprise a chain transmission as shown in Fig. 7. The first transmission TM1 could alternatively comprise a belt or a combination of gear wheels.

[0060] The fifth transmission TM5 comprises the first gear wheel 42a and a COS gear wheel 72. The sixth transmission TM6 comprises the second gear wheel 42b, a third gear wheel 71, and the COS gear wheel 72. The COS shaft 73 is directly connected to the COS gear wheel 72 and corotates with the COS gear wheel 72.

[0061] Coupling C5 (not shown in Fig. 7) is driven by the first shaft 43a. As the first shaft 43a and the second shaft 43b are always coupled by the first transmission TM1, driving either of the first coupling Cl or the second coupling C2 causes both the first shaft 43a and the second shaft 43b to rotate, thereby driving coupling C5.

[0062] Fig. 8 schematically illustrates the arrangement of the COS and VI in an example of the disclosure. Power source 81 is switchably connected to load 82. VI 83 and COS comprising COS contacts 86 are connected in series between the power source 81 and the load 82. When COS contacts 86 are in the service position S the power source and the load are connected. When the COS contacts are in the neutral position N the load 82 is connected to a neutral line 85, and when the COS contacts 86 are in the earth position E, the load 82 is connected to earth 84. The positions of the power source 81 and the load 82 can be interchanged without changing the operation of the system.

[0063] The above described embodiments provide an actuating mechanism for a three- position switchgear device that allows simple and unambiguous operation via simultaneous operation of the VI and a COS.

Claims

Claims1. A medium-voltage switchgear comprising: a three position changeover switch having changeover switch contacts (86) that are moveable between a service position (S), a neutral position (N) and an earth position (E); a vacuum interrupter (83) having vacuum interrupter contacts that are moveable between an open position and a closed position; and a mechanical actuation mechanism for manually operating the changeover switch and the vacuum interrupter (83), wherein the mechanical actuation mechanism is configured such that: when the changeover switch contacts (86) are moved from the service position (S) to the neutral position (N), the mechanical actuation mechanism causes the vacuum interrupter contacts to be moved into the open position before the changeover switch contacts (86) leave the service position.

2. The medium-voltage switchgear of claim 1, wherein the mechanical actuation mechanism is configured to provide one or more of the following operations: when the changeover switch contacts (86) are moved from the neutral position (N) to the earth position (E), the mechanical actuation mechanism causes the vacuum interrupter contacts to be moved into the closed position after the changeover switch contacts (86) reach the earth position (E); when the changeover switch contacts (86) are moved from the earth position (E) to the neutral position (N), the mechanical actuation mechanism causes the vacuum interrupter contacts to be moved into the open position before the changeover switch contacts (86) leave the earth position (E); when the changeover switch contacts are moved from the neutral position (N) to the service position (S), the mechanical actuation mechanism causes the vacuum interrupter contacts to be moved into the closed position after the changeover switch contacts (86) reach the service position (S).

3. The medium-voltage switchgear of claim 1 or claim 2, further comprising a service gate and an earth gate, wherein the mechanical actuation mechanism is configured such that:mechanical actuation of a first coupling (Cl) disposed within the service gate causes movement of the changeover switch contacts between the service position (S) and the neutral position (N); and mechanical actuation of a second coupling (C2) disposed within the earth gate causes movement of the changeover switch contacts between the earth position (E) and the neutral position (N).

4. The medium-voltage switchgear of claim 3, further comprising a gate selection mechanism configured such that only one of the service gate and the earth gate can be opened at one time.

5. The medium-voltage switchgear of claim 3 or claim 4, wherein the first coupling is configured to be mechanically actuated by rotating a handle inserted into the service gate, and the second coupling is configured to be mechanically actuated by rotating the handle when inserted into the earth gate.

6. The medium-voltage switchgear of any of claims 3 to 5, wherein mechanical actuation of the first coupling (Cl) in a first direction causes: movement of the changeover switch contacts from the service position to neutral position, and actuation of a trip shaft leading to opening of the vacuum interrupter contacts before the changeover switch contacts leave the service position; and wherein mechanical actuation of the first coupling (Cl) in a second direction causes: movement of the changeover switch contacts from the neutral position to the service position; and driving of a vacuum interrupter shaft to load a spring buffer, causing closing of the vacuum interrupter contacts at the end of the range motion, after the changeover switch contacts have arrived at the service position.

7. The medium-voltage switchgear of claim 6, wherein mechanical actuation of the second coupling (C2) in the second direction causes: movement of the changeover switch contacts from the neutral position to the earth position; anddriving of the vacuum interrupter shaft to load the spring buffer, causing closing of the vacuum interrupter contacts at the end of the range motion, after the changeover switch contacts have arrived at the earth position, and wherein mechanical actuation of the second coupling (C2) in the first direction causes: movement of the changeover switch contacts from the earth position to the neutral position; and actuation of the trip shaft leading to opening of the vacuum interrupter contacts before the changeover switch contacts leave the earth position.

8. The medium-voltage switchgear of any of claims 6 to 7, wherein the mechanical actuation mechanism comprises a third coupling (C3) and a fifth coupling (C5), wherein the third coupling (C3) is a unidirectional coupling that is driven when the first coupling (Cl) is rotated in the first direction and idles when the first coupling (Cl) is rotated in the second direction, and wherein the fifth coupling (C5) is a unidirectional coupling that is driven when the first coupling (Cl) is rotated in the second direction and idles when the first coupling (Cl) is rotated in the second direction.

9. The medium-voltage switchgear of claim 8, wherein when the first coupling (Cl) rotates in the first direction, the third coupling (C3) drives the trip shaft leading to opening of the vacuum interrupter contacts; and when the first coupling (Cl) rotates in the second direction, the fifth coupling (C5) drives the vacuum interrupter shaft causing closing of the vacuum interrupter contacts.

10. The medium-voltage switchgear of any of claims 8 to 9, wherein the third coupling (C3) comprises a first ratchet-key (51), wherein the first ratchet-key (51) is configured to be actuated by a second protrusion (45) of a handle (40) used to mechanically actuate the first coupling (Cl) when the first coupling (Cl) is rotated in the first direction, and wherein the first ratchet-key (51) allows the second protrusion (45) to pass when the handle (40) is rotated in the second direction.

11. The medium-voltage switchgear of any of claims 8 to 10, wherein the mechanical actuation mechanism comprises a fourth coupling (C4), wherein the fourth coupling (C4) is a unidirectional coupling that is driven when the second coupling (C2) is rotated in the first direction and idles when the second coupling (C2) is rotated in the second direction, and wherein the fifth coupling (C5) is driven when the second coupling (C2) is rotated in the first direction and idles when the second coupling (C2) is rotated in the second direction.

12. The medium-voltage switchgear of claim 11, wherein when the second coupling (C2) rotates in the first direction, the fourth coupling (C4) drives the trip shaft leading to opening of the vacuum interrupter contacts; and when the second coupling (C2) rotates in the second direction, the fifth coupling (C5) drives the vacuum interrupter shaft causing closing of the vacuum interrupter contacts.

13. The medium-voltage switchgear of any of claims 10 to 12, wherein the fourth coupling (C4) comprises a second ratchet-key (56), wherein the second ratchet-key is actuated by a second protrusion (45) of a handle (40) used to mechanically actuate the second coupling (C2) when the second coupling (C2) is rotated in the first direction, and wherein the second ratchet-key (51) allows the second protrusion (45) to pass when the handle (40) is rotated in the second direction.

14. The medium-voltage switchgear of claim 3 to 13, wherein the first coupling (Cl) comprises a first gear wheel (42a) and a first shaft (42b) that can rotate freely with respect to each other when they are not engaged by a handle, wherein the first gear wheel (42a) and the first shaft (42b) comprise openings (44) configured such that insertion of a first protrusion of the handle into the openings (44) causes the first gear wheel (42a) and the first shaft (42b) to be rotationally coupled to each other.

15. A method of operating the medium-voltage switchgear of any preceding claim, the method comprising at least one of: inserting a handle (40) into a service gate and rotating the handle to drive a first coupling (Cl); orinserting the handle (40) into the earth gate and rotating the handle to drive the second coupling (C2).

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