EP3901977A1

EP3901977A1 - Operating mechanism for controlling an earthing switch of a medium voltage switchgear

Info

Publication number: EP3901977A1
Application number: EP20170814.6A
Authority: EP
Inventors: Simone Rambaldini; Andrea Arvati
Original assignee: ABB Schweiz AG
Current assignee: ABB Schweiz AG
Priority date: 2020-04-22
Filing date: 2020-04-22
Publication date: 2021-10-27
Also published as: CN113539729A

Abstract

The present invention relates to an operating mechanism (1) for M.V. earthing switch comprising an operating disk (10) rotating about a main axis (100), a connecting assembly (11) which connects operatively said operating disk (10) to said earthing switch. The operating mechanism (1) also comprises an operating lever (12) for rotating said disk (10) from a first angular position to a second angular position according to a closing movement (Wl) and from second angular position to said first angular position according to an opening movement (W2). According to the invention the operating mechanism (1) comprises an interlock assembly (15) that prevents a re-closing movement of said disk (10) when, starting from said second angular position and according to said opening movement, said disk (10) reaches a pre-established angle (α).

Description

The present invention relates to an electric switchgear for medium-voltage applications. More particularly, the present invention relates to an operating mechanism for controlling an earthing switch addressed to be installed in a medium voltage switchgear.
Electric switchgears are well known in electric power transmission and distribution grids. They usually comprise a metallic cabinet internally divided into several compartments or cells accommodating various apparatuses and equipment. In many applications, electric switchgears include a switching apparatus (e.g. a circuit breaker) of the withdrawable type, i.e. reversibly movable between a first position (inserted position), in which the switching apparatus is electrically connected with the disconnection contacts of the switchgear, and a second position (withdrawn position), in which the switching apparatus is electrically disconnected from said disconnection contacts.
Electric switchgears of the above-mentioned type generally include also an earthing switch assembly. The latter typically comprises an earthing switch, an operating mechanism for controlling the earthing switch and mechanical connection means, typically connection levers, which operatively connect the earthing switch to the operating mechanism. The earthing switch comprises a mechanism for moving a plurality of moving contacts between a first reference position, characteristic of an opening condition of the earthing switch and a second reference position characteristic of a closing condition of the earthing switch. In the second reference position, the movable contacts engage fixed contacts each of one electrically connected to an electric line.
In some known solution, the mechanism of the earthing switch comprises a shaft on which the movable contacts are rigidly mounted. The shaft rotates about a longitudinal axis so that also the movable contacts can rotate correspondingly between said reference positions. The rotation is controlled by an operating mechanism above cited. The operating mechanism typically comprises a rotating disk or a shaft operatively connected to the main shaft of the earthing switch mechanism so that a rotation of the disk results in a rotation of the earthing switch shaft supporting the movable contacts. The disk can be rotated by means of an operating lever to change the condition of the earthing switch. For safety reasons, the operating mechanism is located far enough away from the earthing switch (1000-2000 mm) and it is operatively connected to the shaft of the earthing switch mechanism by connection means (a lever system). The operating lever allows the rotation of the disk between a first angular position, characteristic of an opening condition of the earthing switch, and a second angular position characteristic of a closing condition of the earthing switch.
Usually, the earthing switch comprises spring means operatively connected to the shaft that supports the moving contacts. In some known solutions, the spring means are loaded during a first phase of the closing movement, i.e. during a first phase of rotation of the shaft and of the movable contacts mounted thereof. As soon as the rotation angle (few degree) overcomes a pre-established value, the spring means discharge their elastic energy on the shaft so as to bring the movable contacts instantly and correctly in the second reference position, i.e. in electrical connection with the fixed contacts. According to other known solutions, the spring means are loaded during the opening movement of the earthing switch.
In any case, the closing operation of the earthing switch comprises a first phase performed by an operator acting on the operating lever above indicated and a second phase, not controllable by the operator, determined by the release of the energy of the spring means. Therefore, the closing operation is only partially dependent from the operator. On the contrary, the opening of the earthing switch is an operation totally dependent on the will and the force of the operator. That means, during the opening movement, substantially in any angular position, the operator is allowed to stop the opening movement and to start a re-closing movement, i.e. to bring back the disk in the position corresponding to the closing condition of the earthing switch.
It has been seen that such a re-closing movement is not safe. Acting on the operating lever of the disk, the operator should apply the torque necessary to restore the right electrical connection between the moving contacts and the fixed contacts of the earthing switch. However, such a torque could be insufficient to recover the tolerance chain relative to the components of the operating mechanism and of the earthing switch mechanism provided for rotating the moving contacts. Following a manual re-closing movement, the moving contacts could be in contact, but not completely electrically coupled to the fixed contacts. In case of a short-circuit current, the moving contacts could move away from the fixed contact generating an electric arc with very dangerous consequences.
The main aim of the present invention is providing an operating mechanism for controlling a medium voltage earthing switch, which makes it possible to overcome or mitigate the aforementioned problems of the known art.
In the context of this aim, an object of the present invention is providing an operating mechanism which allows to achieve the closing condition of the earthing switch in a safe way and to keep such a condition avoiding dangerous manoeuvres.
Another object of the present invention is providing an operating mechanism in which the closing condition of the earthing switch cannot be reached only by a manual intervention of an operator.
A further object is providing an operating mechanism in which the closing movement of the earthing switch always involves the action of the spring means associated to the earthing switch.
Yet another object of the present invention is providing an operating mechanism easy to manufacture at industrial level, at competitive costs with similar installations of the state of the art.
This aim and these objects, together with other objects that will become evident from the following description and accompanying drawings, are achieved, according to the present invention, by an operating mechanism, according to claim 1 and the related dependent claims set out below.
In a general definition, the operating mechanism, according to the invention, comprises an operating disk rotating about a main axis between a first angular position and a second angular position that correspond, respectively, to an opening condition and to a closing condition of the earthing switch. The mechanism also comprises a connecting assembly which connects operatively said operating disk to the earthing switch and an operating lever for rotating the disk from the first angular position to the second angular position according to a closing movement and vice-versa according to an opening movement; the connecting assembly is configured so as to transform the closing and the opening movement of the disk, respectively, in a closing and an opening movement of the earthing switch.
According to the invention, the operating mechanism comprises an interlock assembly that prevents a re-closing movement of the disk when, starting from said second angular position and according to said opening movement, the disk reaches a pre-established angle. Advantageously, the interlock assembly avoids the return of the earthing switch in the closing condition unless the opening movement is completed. This means that the closing movement of the earthing switch can always exploit the elastic energy of spring assembly associated with the opening/closing mechanism installed on the earthing switch. Therefore, at the end of the closing movement, the moving contacts reach always the correct position which ensure a safe electrical connection with the fixed contacts.
Preferably the interlock assembly comprises a first sub-assembly integral with said disk and a second sub-assembly which interacts with the first sub-assembly, wherein the second sub-assembly is mounted on a fixed frame.
According to a preferred embodiment, the first sub-assembly comprises a first element integral with the disk, while the second sub-assembly comprises a first element hinged to said frame. The first rotating element rotates under the action of a at least one first spring element. At a locking position, the first rotating element cooperates with the first element of the first sub-assembly to prevent said re-closing movement.
According to a preferred embodiment, the first sub-assembly comprises a second element integral with the disk, wherein, during the rotation of said disk according to said opening movement, the second element moves the first rotating element from said locking position to an unlocking position loading said at least one first spring element; the second sub-assembly comprises a second rotating element hinged to the frame and subjected to the action of at least one second spring element. Such a second rotating element locks said first rotating element when the latter reaches the unlocking position.
Preferably, the first rotating element reaches the unlocking position when the disk reaches said second angular position. Preferably, when the disk is at the second angular position, the first rotating element of the second sub-assembly rests against the first element of the first sub-assembly.
According to an embodiment of the present invention, the first sub-assembly comprises a third element, integral with said disk, which, during said closing movement, acts on the second rotating element so as to move it from the locking position and to make the first element of the second sub-assembly free to rotate under the action of said at least one spring element.
Preferably, the third element is fixed to the disk in a position angularly interposed between the position of said first element and of said second element.
According to an embodiment, the first element and the second element of the second sub-assembly rotate, respectively, about a first rotation axis and a second rotation axis parallel to said main axis.
According to a preferred embodiment of the frame, it comprises a pair of side walls opposite each other and that develop on planes substantially orthogonal to the main axis; the frame also comprises a longitudinal wall which develops parallelly to the main axis between the side walls in a position distal from the disk so that the second sub-assembly is substantially arranged between said disk and the longitudinal wall.
According to a preferred embodiment, the first element and/or the third element of the first sub-assembly are rigidly connected to a cylindrical peripheral surface of the disk. Preferably, the second element of the first sub-assembly is plate shaped and connected to a main surface of the disk.
According to a possible embodiment of the second sub-assembly, the first rotating element of the second sub-assembly comprises a first portion and a second portion that is fork shaped; said at least one first spring element is connected between the frame and the first portion; the second portion interacts with the first element of the first sub-assembly to prevent said re-closing movement. The second portion defines a central slot for the passage of the third element of the first sub-assembly during the opening movement of the disk and when the first rotating element is at said locking position.
Preferably, the second rotating element of the second sub-assembly comprises a front portion faced to the disk and a rear portion opposed to the front portion; the second spring element is connected to the rear portion and to a wall of the frame. The front portion is provided with a locking pawl that protrudes towards the first rotating element; the first portion of the first rotating element comprises a bottom seat in which the locking pawl inserts when the first rotating element reaches the unlocking position due to the action of the second element of the first sub-assembly.

LIST OF DRAWINGS

Further characteristics and advantages of the invention will emerge from the description of preferred, but not exclusive embodiments of an operating mechanism according to the present disclosure, non-limiting examples of which are provided in the attached drawings, wherein:

figure 1 is a perspective view of an operating mechanism according to the present invention;
figure 2 is a frontal view of the operating mechanism of figure 1;
figure 3 is a plan view of the operating mechanism of figures 1 and 2;
figure 4 is a section view according to line IV-IV of figure 2;
figure 5 is an enlargement view of the detail V of figure 4;
figure 6 is a view of some components of the operating mechanism of figures 1 and 2;
figure 7 is a view of a part of a sub-assembly of the components of figure 6;
figure 8 is a section view according to section line VIII-VIII of figure 7;
figures 9-12 are schematic views of the operating mechanism of figures 1 and 2 each of one refers to a phase of an opening movement;
figures 13-16 are schematic views of the operating mechanism of figures 1 and 2 each of ne refers to a phase of a closing movement.

DETAILED DESCRIPTION

Referring to the above-mentioned figures, the present invention relates to an operating mechanism 1 for controlling an earthing switch usable for medium voltage applications. For the purposes of the present invention, the term "medium voltage" (MV) relates to operating voltages higher than 1 kV up to some tens of kV, e.g. 70 kV AC and 100 kV DC.
The operating mechanism 1 is usable in a MV switchgear and operatively connectable to an earthing switch (not shown in the figures) arranged in a position relatively away from the mechanism 1 (typically 1-2 meters). The operating mechanism 1 is usable independently on the configuration of the mechanism of the earthing switch provided to rotate the moving contacts.
The operating mechanism 1 is arranged in a casing 80 that is connectable to the switchgear or that can be a part of it. The casing 80 comprises a base 81 and two opposite flanks 81A, 81B which develop orthogonally from the base 81. The most of the components of the mechanism 1 is arranged between the flanks 81A, 81B. Preferably, the casing 80 also comprises a rear wall 82 and a front panel 83 opposed to the rear wall 82. According to a possible embodiment, the base 81 and the real wall 82 could be defined by a sole metal sheet L shaped. The mechanism 1 comprises an operating disk 10 rotating about a main axis 100. The disk 10 is mounted on a shaft 110 which is supported, inside the casing 80, by the flanks 81A, 81B at opposite ends. As indicated in figure 8, the disk 10 comprises two main surfaces 10A mutually opposed that develop on parallel planes orthogonal to the main axis. The disk 10 also comprises a cylindrical peripheral surface 10B that develops between the two main surfaces 10A of the disk 10.
The disk 10 is configured so as to assume a first angular position and a second angular position, which are characteristic, respectively, of an opening condition and of a closing condition of said earthing switch. The angular positions are considered with respect to the main axis 100. Therefore, a movement from said first angular position to said second angular position, or vice versa, corresponds to a rotation of the disk 10 of a pre-established angle β.
In figure 6, the disk 10 is shown in the second reference position (closing condition). The references axes X-X and Y-Y are indicated on a plane orthogonal to the main axis 100. Figure 12 shows the disk 10 in the first angular position (opening condition). Preferably, said pre-established angle β is about 90° as clear evident from the comparison of Figures 6 and 12. The operating mechanism 1 comprises a connecting assembly 11 (see figures 1 and 3) configured to connect the operating disk 10 with the earthing switch (not shown) so that a rotation of the disk 10 determines a change of the earthing switch condition. More in detail, according to a solution per-se known, the connecting assembly 11 turns the rotation of the disk 10 in a corresponding rotation of the shaft of the earthing switch mechanism to which the moving contacts are rigidly connected.
Preferably, the connecting assembly 11 comprises two connecting levers 11A, 11B (see figure 1) hinge at a lever 111 mounted at one end 110A of the shaft 110 supporting the disk 10. More in detail, the connecting levers 11A, 11B are hinged at points of said lever 111 diametrically opposed with respect to the main axis 100.
The operating mechanism 1 also comprises an operating lever 12 for rotating the disk 10 between said angular positions (first and second) above defined. More precisely, the operating lever 12 allows to rotate the disk 10 from said first angular position (see Figure 12) to said second angular position according to a closing movement W1 and from said second angular position (see figure 9) to said first angular position according to an opening movement W2. The connecting assembly 11 is configured so that the closing movement W1 and the opening movement W2 of the disk 10 result, respectively, in a closing movement and in an opening movement of the earthing switch. As a fact, the lever 12 is the means that allows the operator to change, via the disk 10, the configuration of the earthing switch.
According to a preferred embodiment, the front panel 83 comprises a slot 83A from which a handling part 12A of the operating lever 12 protrudes (see figure 4). A fixing part 12B of the lever 12 is connected to the disk 10 inside the casing 80. An operator can grasp the handling part to rotate the disk 10. Referring to a normal installation position, when the operating disk 10 is at the first angular position, the lever 12 is oriented downwards (see figure 12). On the contrary, the operating disk 10 is at the second angular position, the lever 12 is oriented upwards (see figure 4).
Preferably, the lever 12 is connectable to the disk 10 in a removable way by coupling means configured so that the lever 12 can be separated from, or connected, to the disk 10 only if the latter is at one of said angular positions (first or second). Therefore, the lever 12 can be removed from the disk 10 only when a corresponding manouvre (opening or closing) has been completed, without that any part of it protrudes anymore from the front panel 83 as shown in figures 1 and 3.
According to the invention, the operating mechanism 1 comprises an interlock assembly 15 that prevents a re-closing movement of the disk 10 when, during the opening movement W2, it reaches, starting from said second angular position, a pre-established angle α. In particular the interlock assembly 15 prevents the return of the disk 10 in the second angular position (i.e. said re-closing movement) unless the opening movement is completed. In other words, when the disk 10 reaches, during the opening movement W2, a pre-established angular position (corresponding to said angle α) the interlock assembly 15 avoids the rotation of the disk 10 in a direction corresponding to said closing movement W1. The locking of the disk 10 is removed only if the opening movement is completed, that if the disk 10 reaches the first angular position. Therefore, for an operator acting on the lever, it is mandatory to complete the opening movement W2 in order to unlock the disk 10 and to bring back, by means of a subsequent closing movement W1 of the disk 10, the earthing switch in the closing condition. According to a preferred embodiment shown in the figures, the interlock assembly 15 comprises a first sub-assembly 15A integral with the disk 10 and a second sub-assembly 15B separated from said disk 10 and that interacts with the first-assembly 15A. In Figure 8, the components (31, 32, 33) of the first sub-assembly 15A are grouped by a dashed line. More precisely, the first sub-assembly 15A comprises a plurality of element 31, 32, 33 that are rigidly mounted on said disk 10 so that they can rotate with the disk 10 about the main axis 100. The second sub-assembly 15B comprises a plurality of elements 41, 42, 51A, 51B, 52 mounted on a fixed frame 5 separated from the disk 10.
According to a possible embodiment shown in the figures, the frame 5 comprises a pair of the side walls 512A, 512B opposite each other and that develop on planes substantially orthogonal to the main axis 100 of the disk 10. The side walls 512A, 512B are preferably mounted on the base 81 of the casing 80.
The frame 5 also comprises a longitudinal wall 513 that develops parallelly to the main axis 100 and that connects the two side walls 512A, 512B. As clearly shown in figure 8, the frame 5 is arranged so that the longitudinal wall 513 is placed in a position relatively distal from the disk 10 so that the most of the elements of the second sub-assembly 15B is arranged between the longitudinal wall 513 and the disk 10 according to a reference direction T orthogonal to the main axis 100.
According to a possible embodiment, the first sub-assembly 15A comprises a first element 31 fixed to the disk 10, preferably on its peripheral cylindrical surface 10B. The second sub-assembly 15B comprises a first rotating element 41 hinged to said frame 5 so as to rotate about a first axis 101 under the action of at least one spring element 51A, 51B (see figure 7). Preferably, the second sub-assembly 15B comprises a pair of spring elements 51A, 51B each of one connected between the first rotating element 41 and a corresponding of said side walls 512A, 512B.
In a locking position, the first rotating element 41 of the second sub-assembly 15B cooperates with the first element 31 of the first sub-assembly 15A to prevent said re-closing movement when, starting from said second angular position (closing condition), the disk 10 reaches said pre-established angle α. In particular, as soon as the disk 10 reaches the angle α, the first rotating element 41 is dragged by the spring elements 51A, 51B in said locking position (see figure 10). The re-closing movement (rotation according to W1) is forbidden because the rotation of the first element 31 integral with the disk 10 is impeded by the first rotating element 41.
Preferably, the first rotation axis 101 of the first element 41 of the second sub-assembly 15B is substantially parallel to the main axis 100 about which the disk 10 rotates. Said spring elements 51A, 51B exert a force on the first element 41 that tends to rotate and to keep it in said locking position.
Preferably, when the disk 10 is at second angular position (closing condition), the first element 41 of the second sub-assembly 15B rests against the first element 31 of the first sub-assembly 15A (see for example figures 5, 6 and 16). As a consequence, the rotation of the disk 10 according to the opening movement W2 causes a counter-rotation, in contrast to the spring elements 51A, 51B, of the first rotating element 41 in an opposite direction (arrow T2 in Figure 9). In particular, such a counter- rotation takes place when the disk 10 reaches said pre-established angle α.
According to a preferred embodiment shown in the figures, the first sub-assembly 15A comprises a second element 32 integral with said disk 10 and angularly distanced from said first element 31. During the opening movement, the second element 32 acts (in contrast to said at least one first spring element 51A, 51B) on the first element 41 of the second sub-assembly 15B so as to rotate it from said locking position to an unlocking position (see figure12). The latter is a position for which a subsequent closing movement (direction W1) is allowed. Preferably, the first rotating element 41 reaches said unlocking position when the disk 10 reaches the first angular position, i.e. when the opening movement is completed (see figure 12).
Preferably, the second element 32 of the first sub-assembly 15A is a plate connected to one of the main surfaces 10A of the disk 10. Such a plate has a portion 32A protruding radially with respect to the peripheral edge 10B and that interacts with the first rotating element 41.
The second sub-assembly 15B comprises a second rotating element 42 hinged to the frame 5 and subjected to the action of a second spring element 52. The second rotating element 42 locks the first rotating element 41 as soon as the latter reaches the unlocking position above indicated. Therefore, the second rotating element 42 avoids the counter-rotation of the first rotating element 41 towards the locking position during a first phase of the closing movement, that means when the second element 32 of the first sub-assembly 15A moves away from the first rotating element 41.
Preferably, the second rotating element 42 rotates about a second rotation axis 102 that is substantially parallel to the first axis 101 and to the main axis 100 above indicated. The second spring element 52 exerts a force on the second element 42 that tends to rotate and to keep it in a first operative position at which it locks the first rotating element 41. Therefore, when the second rotating element 42 locks the first rotating element 41, the second spring element 52 is partially discharged. The second spring element 52 preserves a part of elastic energy to assure the correct engagement of the second rotating element 42 with the first rotating element 41, as below better described.
Preferably, the second spring element 52 is arranged so as to rotate the second rotating element 42 according to a direction opposed to that around which the first rotating element 41 tends to rotate under the action of the at least one spring element 51 A, 52B.
Preferably, the second rotating element 42 contacts the first rotating element 41 so that the locking position of the first rotating element 41 also depends on the action of the second spring element 52. Preferably, the frame 5 is provided with a fixed element 59 against which the first rotating element 41 abuts due to the combined action of the first spring element 51A, 51B and of the second spring element 52. Overall, the spring elements 51A, 51B, 52 and the fixed element 59 establish the locking position of the first rotating element 41 of the second sub-assembly 15B (see Figure 10).
According to a preferred embodiment, the first sub-assembly 15A comprises a third element 33, integral with the disk 10 and preferably connected to it at the cylindrical peripheral surface 10B. During the closing movement (see figures 14 and 15), the third element 33 acts on the second rotating element 42 of the second sub-assembly 15B so as to move it from its operative position and to make the first rotating element 41 free to rotate around the first axis 101 due to the action of the spring elements 51A, 51B. In particular, the third element 33 is fixed to the disk 10 in a position angularly interposed between the positions of said first element 31 and of said second element 32. Therefore, during the closing movement and following the unlocking of the first rotating element 41 due to the third element 33, the first element 31 reaches its reference position before that the first rotating element 41 reaches its locking position (see figures 15 and 16).
According to a preferred embodiment shown in the figures, the first rotating element 41 comprises a first portion 41A and a second portion 41B fork shaped (see figure 7). The two portions 41A, 41B are substantially opposed with respect to the first axis 101. That means, with respect to a horizontal installation of the frame 5 (see figure 7) the first portion 41A and the second portion 41B develop, respectively, above and below the first axis 101. A first spring element 51A is connected between a first end 410A of the first portion 41A and a first side wall 512A of the frame 5, while a second spring element 51B is connected between a second end 410B of the first portion 41A and a second side wall 512B (see again Figure 7). The second portion 41B fork shaped interacts with the first element 31 of the first sub-assembly 15A in order to prevent the re-closing movement as above indicated. At the end of the opening movement, the second rotating element 42 locks the first rotating element 41 acting on the first portion 41A.
The second portion 41B defines a central slot 44 for the passage of the third element 33 during the opening movement of the disk. More precisely, the slot 44 allows the passage of third element 33 when the first rotating element 41 is at its locking position (see figure 10). Therefore, the shape and dimensions of the slot 44 are defined as a function of those of the third element 33 connected to the peripheral edge 10B of the disk 10.
The second rotating element 42 is mounted on a shaft 43 supported by the side walls 512A, 512B of the frame 5 so as to define said second axis 102. The second rotating element 42 comprises a front portion 42A and a rear portion 42B. Such portions 42A, 42B are substantially opposed with respect to the second axis 102. During the closing movement, the front portion 42A is contacted by the third element 33 of the first sub-assembly 15A, while the rear portion 42B is subjected to the action of the second spring element 52. Preferably, the longitudinal wall 513 of the frame 5 comprises a slot 513A (see figure 7) from which an end 420B of the rear portion 42B protrudes (see figure 5). A fixing element 49 is installed on the outer wall 513B of the longitudinal wall 513 near its bottom part 513C. The second spring element 52 is connected between the end 420B of the rear portion 42B and said fixing element 49.
With reference again to figures 7 and 8, the front portion 42A of the second rotating element 42 is provided with a locking pawl 47 protruding upward, i.e. towards the first rotating element 41. The first portion 41A of the first rotating element 41 comprises a bottom seat 48 in which the locking pawl 47 inserts when the first rotating element 41 reaches the unlocking position due to the action of the second element 32 of the first sub-assembly 15A. In particular, the engaging of the locking pawl 47 with the bottom seat 48, in combination with the action of second spring element 52, keeps effectively the first rotating element in the unlocking position until the intervention of the third element 33 of the first sub-assembly 15A.
With reference to the figures 8-16, the working principle of the operating mechanism 1 is explained below. Figure 9 shows the operating mechanism 1 in a configuration corresponding to a closing condition of the earthing switch. The disk 10 is at the second angular position and consequently the first element 31 of the first sub-assembly 15A is at its reference position. The first rotating element 41 of the second sub-assembly 15B abuts against the first element 31 of the first sub-assembly 15A under the action of the pair of spring elements 51A, 51B. The second rotating element 42 is kept separated by the first rotating element 41 by the third element 33 of the first sub-assembly 15A. In particular, such a third element 33 keeps the second rotating element 42 rotated with respect to its operative position by charging, as a consequence, the second spring element 52.
With respect to the installation shown in figure 9, the opening movement W2 is the result of a rotation of the disk 10 in the counter clock wise direction about the main axis 100. Such a rotation is performed by means of the operating lever 12. When the opening movement W2 begins, the first element 31 rotates with the main disk 10 causing a counter rotation of the first rotating element 41 in a clock wise direction (indicated by the arrow T2). As soon as the disk 10 rotates of said pre-established angle α, the contact between the first element 31 and the first rotating element 41 is lost. Therefore, due to the action of the pair of spring elements 51A, 51B the first rotating element 41 is rotated in the counter-clock direction (indicated by the arrow T3) up to reaches the locking position (see Figure 10). As above indicated, preferably, the locking position is not only depending on the first spring elements 51A, 51B, but also on the second spring element 52 acting on the second rotating element 42, in contact with the first rotating element 41, as well as on the reference element 59, preferably fixed to the rear wall 83 of the frame 5. As shown in figure 19, in the locking position the first rotating element 59 abuts against such a reference element 59.
In such a condition (locking position), the first rotating element 41 avoids the return of the disk 10 towards the second angular position. Therefore, for an operator any re-closing movement (direction W1) is prevented. The only possibility to restore the closing condition is to compete the opening movement, i.e. to rotate the disk 10 up to reach the first angular position.
In order to complete the opening movement, an operator have to continue to push the operating lever 12 downwards. This results into a rotation of the disk 10 (according to the direction W2) and consequently of the elements 31, 32, 33 of the first sub-assembly 15A. As shown in figure 11, as the disk 10 approaches the first angular position (opening condition), the second element 32 of the first sub-assembly 15A acts on the first rotating element 41 causing its rotation, about the first axis 101, in a clockwise direction (direction T2) and causing the loading of the pair of spring elements 51A, 51B. In the meantime, also the second rotating element 42 is dragged in a clockwise rotation (direction L2) determined by the second spring element 52. In particular, the second rotating element 42 rotates in contact with the first rotating element 41, in particular with its first portion 41A.
Figure 12 shows the operating mechanism 1 when the disk 10 reaches the first angular position (i.e. earthing switch in opening condition). With respect to the initial condition shown in figure 9, the disk 10 ha rotated of an angle β of about 90°. In the opening condition of Figure 12, the action of the second element 32 of the first sub-assembly 15A is ended and the first rotating element 41 is at its unlocking position. At the same time, the second rotating element 42 is at its operative position for which the locking pawl 47 of the second rotating element 42 is inserted in the bottom seat 48 so that the first rotating element 41 is effectively locked. In view of the of the action of the second rotating element 42, the first rotating element 41 keeps the unlocking position even when, during the subsequent closing movement, the contact with the second element 32 of the first sub-assembly 15A is lost (see figure 13).
On this regards, Figures 13 to 16 refer to the closing movement, i.e. the rotation of the disk 10 from the first angular position (figure 12) to the second angular position (figure 16). As shown, in Figure 13, the closing movement is performed by means of an upwards movement of the operating lever 12 that results in a clockwise rotation (direction W1) of the disk 10 about the main axis 100. In view of such a rotation, the second element 32 of the first sub-assembly 15A moves away from the first rotating element 41 locked by the second rotating element 42 (see figures 13 and 14). At the same time, the third element 33 of the first sub-assembly 15A approaches the front part 42A of the second rotating element 42 (see figure 14). During such a rotation, the second element 32 does not interfere with the second rotating element 42 by virtue of its installation on a main face 10A of the disk 10.
Figure 15 shows the operating mechanism 1 at the instant wherein the third element 33 of the first sub-assembly 15A begins to act on the second rotating element 42 rotating it in a counter-clock wise direction (indicated with L3). As shown, in such an instant the first element 31 has already reached a position for which the first rotating element 41 cannot reach the locking position. The action of the third element 33 releases the locking pawl 47 of the second rotating element 42 from the seat 48 of the first rotating element 41 making the latter free to rotate in a counter-clock wise direction (arrow T3) under the action of the pair of spring elements 51A, 51B. As above, the first rotating element 41 can not reach the locking position and abuts against the first element 31 of the first sub-assembly 15A. On this regard, figure 16 shows the condition reached at the end of the closing movement, that corresponds exactly to that shown in Figure 9. Figures 9-16 are a sequence of views showing the working of the operating mechanism 1 during an opening movement and a subsequent closing movement.
The operating mechanism, according to the invention, can be easily realized at industrial levels. Thus, it can be easily manufactured at competitive costs with similar installations of the state of the art.

Claims

Operating mechanism (1) for M.V. earthing switch comprising:
- an operating disk (10) rotating about a main axis (100) between a first angular position and a second angular position that correspond, respectively, to an opening condition and to a closing condition of said earthing switch;

- a connecting assembly (11) which connects operatively said operating disk (10) to said earthing switch;

- an operating lever (12) for rotating said disk (10) from said first angular position to said second angular position according to a closing movement (W1) and from second angular position to said first angular position according to an opening movement (W2), wherein said connecting assembly (11) transforms said closing movement (W1) and said opening movement (W2) of said disk (10), respectively, in a closing movement and in an opening movement of said earthing switch,
characterized in that said operating mechanism (1) comprises an interlock assembly (15) that prevents a re-closing movement of said disk (10) when, starting from said second angular position and according to said opening movement (W2), said disk (10) reaches a pre-established angle (α).
The mechanism (1) according to claim 1, wherein said interlock assembly (15) comprises a first sub-assembly (15A) integral with said disk (10) and a second sub-assembly (15B) which interacts with said first sub-assembly (15A), said second sub-assembly (15B) being mounted on a fixed frame (5).
The mechanism (1) according to claim 2, wherein said first sub-assembly (15A) comprises a first element (31) integral with said disk (10) and said second sub-assembly (15B) comprises a first element (41) hinged to said frame (5) and rotating under the action of at least one first spring element (51A, 51B), wherein in a locking position said first rotating element (41) cooperates with said first element (31) of said first sub-assembly (15A) to prevent said re-closing movement.
The mechanism (1) according to claim 3, wherein said first sub-assembly (15A) comprises a second element (32) integral with said disk (10), wherein, during the rotation of said disk (10) according to said opening movement (W2), said second element (32) moves said first rotating element (41) from said locking position to an unlocking position loading said at least one first spring element (51A, 51B), and wherein said second sub-assembly (15B) comprises a second rotating element (42) hinged to said frame (5) and subjected to the action of at least one second spring element (52), said second rotating element (42) locking said first rotating element (41) when the latter reaches said unlocking position.
The mechanism (1) according to claim 4, wherein the first rotating element (41) reaches said unlocking position when said disk (10) reaches said second angular position.
The mechanism (1) according to claim 4 or 5, wherein said first sub-assembly (15A) comprises a third element (33), integral with said disk (10), that during said closing movement acts on said second rotating element (42) so as to move it from said locking position and to make said first element (41) of said second sub-assembly (15B) free to rotate under the action of said at least one spring element (51A, 51B).
The mechanism (1) according to claim 6, wherein said third element (33) is fixed to said disk (10) in a position angularly interposed between the position of said first element (31) and of said second element (32).
The mechanism (1) according to claim 7, wherein said first element (41) and said second element (42) of said second sub-assembly (5) rotate, respectively, about a first rotation axis (101) and a second rotation axis (102) parallel to said main axis (100).
The mechanism (1) according to anyone of the claims 3-8, wherein when said disk (10) is at second angular position, said first rotating element 41 of said second sub-assembly (15B) rests against said first element (31) of said first sub-assembly (15A).
The mechanism (1) according to any of the claims 2-9, wherein said frame (5) comprises a pair of side walls (512A, 512B) opposite each other and that develop on planes substantially orthogonal to said main axis (100), wherein said frame (5) also comprises a longitudinal wall (513) which develops parallelly to said main axis (100) between said side walls (512A, 512B) in a position distal from said disk (10) so that said second sub-assembly (15B) is substantially arranged between said disk (10) and said longitudinal wall (513).
The mechanism (1) according to any of the claims 6-10, wherein said first element (31) and/or said third element (33) of said first sub-assembly (15A) are rigidly connected to a cilindrical peripheral surface (10B) of said disk (10).
The mechanism (1) according to claim any of the claims 5-11, wherein said second element (32) of the first sub-assembly (15A) is plate shaped and connected to a main surface (10A) of said disk (10).
The mechanism (1) according to any of the claim 6-12, wherein said first rotating element (41) of said second sub-assembly (15B) comprises a first portion (41A) and a second portion (41B) that is fork shaped, wherein said at least one first spring element (51A, 51B) is connected between said frame (5) and said first portion (41A), and wherein said second portion (41B) interacts with said first element (31) of said first sub-assembly (15A) to prevent said re-closing movement, said second portion (41B) defining a central slot (44) for the passage of said third element (33) during said opening movement of said disk (10) and when said first rotating element (41) is at said locking position.
The mechanism (1) according to claim 13, wherein said second rotating element (42) comprises a front portion (42A) faced to said disk (10) and a rear portion (42B) opposed to said front portion (42A), wherein said second spring element (52) is connected to said rear portion (42B) and to a wall of said frame (5), wherein said front portion (42A) is provided with a locking pawl (47) that protrudes towards said first rotating element (41) and wherein said first portion (41A) of said first rotating element (41) comprises a bottom seat (48) in which said locking pawl (47) inserts when said first rotating element (41) reaches said unlocking position due to the action of said second element (32) of said first sub-assembly (15A).