EP1529299B1

EP1529299B1 - Drive mechanism for switching installation, and method for operating it

Info

Publication number: EP1529299B1
Application number: EP03788182A
Authority: EP
Inventors: Gerhardus Leonardus Nitert
Original assignee: Eaton Electrics BV
Current assignee: Danfoss Power Solutions II BV
Priority date: 2002-08-15
Filing date: 2003-08-15
Publication date: 2007-02-28
Anticipated expiration: 2023-08-15
Also published as: DE60312169D1; ATE355603T1; WO2004017348A2; PT1529299E; EP1529299A2; AU2003261668A1; ES2281684T3; AU2003261668B2; WO2004017348A3; DE60312169T2; NZ538588A; NL1021286C2; DK1529299T3

Abstract

Drive mechanism for the synchronous operation of a plurality of vacuum circuit breakers (35). It comprises energy storage means (6), conversion means (37) for converting energy stored in the energy storage means (6) into an operation of switching off the vacuum circuit breakers (35) and for switching on the vacuum circuit breakers (35), in which latter process energy is simultaneously stored in the energy storage means (6). The conversion means (37) comprise first transfer means which can move substantially in a first direction and second transfer means which can move substantially in a second direction. The conversion means also comprise at least one connecting rod (4, 4'), which on one side (23, 23') is rotatably secured to the first transfer means and on a second side (22, 22') is rotatably secured to the second transfer means. The drive mechanism also comprises a trip mechanism which interacts with the drive mechanism and a disconnector drive mechanism (70) for the simultaneous operation of disconnectors (73).

Description

The invention relates to a drive mechanism which, with the aid of energy stored in energy storage means and with the aid of conversion means, is used to incorporate a switch composed of one or more vacuum circuit breakers in an electrical circuit or to open this switch therein. The circuit in question may, for example, comprise a cable, the switch and a rail system, in which case the switch connects the cable to the rail system or disconnects it. More particularly, the present invention relates to a drive mechanism according to the preamble of claim 1. In a further aspect, the present invention relates to a method of operating such a drive mechanism, according to the preamble of claim 8.
Such a drive mechanism is e.g. known from patent publication EP-A-0 450 194, which describes a switch drive mechanism. In one of the embodiments described, a selection switch is used to connect a switch field to either a rail system or to ground.
In the case of a three-phase switching installation, switches of this type are composed of three poles, which can each incorporate or interrupt one phase of the installation in the circuit. In this context, it is important for all three poles to be switched on and off simultaneously, so that they operate synchronously as a single switch. This is generally achieved by coupling the levers which actuate the separate poles via a drive shaft. It is also endeavoured to limit switching installation dimensions to the maximum possible degree in order to obtain a compact installation which is easier to install in a limited space.
In addition, drive mechanisms of this type have to be able to have sufficient energy to be able to apply the required switching on and off speeds for the main contacts, which means that considerable forces occur in the mechanism. In order also to ensure a sufficient contact force, considerable forces are required and have to be absorbed by the mechanism.
Furthermore, it has been found that the faults which occur in practice in switching installations are to a significant degree attributable to defects in the drive mechanism.
To improve the reliability and reduce the need for maintenance, it is generally attempted to design the drive mechanism to be as simple as possible, with the minimum possible number of components.
Finally, it has also been found that faults in the operation of switching installations are to a significant degree attributable to the drive mechanism and in particular are caused by the mechanism being affected by the environment, for example corrosion and contamination by dust from the lubricants and drying of the latter.
It is an object of the invention to provide a drive mechanism which complies with the above mentioned conditions imposed on drive mechanisms, in particular with regard to the compactness of the overall switching installation, and in which further simplification and a further reduction in the number of components is achieved compared to known drive mechanisms.
For this purpose, the present invention provides a drive mechanism according to claim 1. The construction using the toggle strip makes it possible to exert a high compressive or tensile force with a relatively low couple at the end of a rotation movement of the disconnector drive shaft.
In a further embodiment, the disconnector drive shaft can be rotated further into a third position, in which each of the plurality of disconnectors forms an electrical connection between the pole of the switching element and a grounding contact, in a grounding position which corresponds to the third position. This makes it possible to ground parts of the switching installation if necessary. It is preferable for the rail position and the grounding position to form the extreme positions of the drive shaft, with the breaking position between them.
The connection between the disconnectors and the poles of the switching elements have both an electrical conduction function and a mechanical function. For example, while maintaining a good electrically conductive connection, a rectilinear up-and-down movement of the switching elements and a rotational movement of the disconnectors about the connection should also be possible. In situations of this type it is customary to use what are known as stranded wire connections. However, these are relatively expensive, require additional assembly work and take up more space. Therefore, according to the invention a sliding connection is used, in which the pivot about which the disconnectors rotate is integrated.
In an advantageous further embodiment, the connection between the radially projecting strip and the toggle strip is connected to a tension spring which pulls the connection towards a stop. This makes it possible to define two stable states (preferably the rail position and the grounding position).
In a further embodiment, the disconnectors move in a plane of movement which is perpendicular to the first direction, so that a compact and operationally reliable structure becomes possible.
In a further embodiment, the drive mechanism also comprises a front module, having a stop button for operating the trip mechanism, a first opening for driving the shaft, a second opening for driving the disconnector drive shaft, and a selector member with three positions, the selector member being designed to open the first opening in a first position, to block the first and second openings in a second position and to open the second opening in a third position. This makes it possible to dictate a predetermined operating sequence, which offers advantages in the field of safety and ease of use.
In yet a further embodiment, the drive mechanism is accommodated in a conditioned room. This means that less contamination which causes faults through corrosion or other mechanisms can occur.
In a further aspect, the present invention relates to a method for operating a switching installation which is equipped with a drive mechanism according to the present invention, in which the switching installation has a first operating state, in which each of the plurality of switching elements is switched off and each of the plurality of disconnectors is in the first position, and a second operating state, in which each of the plurality of switching elements is switched off and each of the plurality of disconnectors is in the third position, and a third operating state, in which each of the plurality of switching elements is switched on and each of the plurality of disconnectors is in the first position. In each of the operating states the selector member is in position two, and the switching installation changes from the first operating state to the second operating state by the selector member being placed in the position three, the disconnector drive shaft being rotated into the grounding state, and the selector member being reset to position two; the switching installation is changed from the second operating state to the first operating state as a result of the selector member being placed in position three, the disconnector drive shaft being rotated into the rail position, and the selector member being reset to position two; the switching installation is changed from the first operating state to the third operating state as a result of the selector member being placed in position one, the shaft being rotated into the switched-on position of the plurality of switching elements, and the selector member being reset to position two; and the switching installation is moved from the third operating state to the first operating state by actuation of the off button.
Defining just four transactions between the three operating states allows unambiguous, reliable and safe operation of the switching installation having the drive mechanism. Each transition entails at most one change in the state of either the switching elements or the disconnectors.
In a further embodiment of the present invention, the drive mechanism may furthermore be in a number of maintenance states, in which the selector member is in the first position. By way of example, it is possible to lock access to the room in which the switching installation is located, or part of it, such as the cable connection compartment, in the second or third position of the selector member. This increases the safety of the switching installation, including during maintenance.
The present invention will be explained below on the basis of a number of exemplary embodiments with reference to the drawing, in which:

Figs. 1a and 1b show a simplified illustration of a drive mechanism in various operating states;
Figs. 2a-c show a simplified illustration of a trip mechanism;
Figs. 3a-d show a simplified illustration of an alternative to the trip mechanism shown in Figs. 2a-c;
Figs. 4a and 4b respectively show a side view and a front view of the drive mechanism for the disconnectors according to one embodiment of the present invention;
Figs. 5a and 5b show an enlarged view of sections Va and Vb from Figs. 4a and 4b;
Fig. 6 shows a plan view of a drive mechanism according to one embodiment of the present invention;
Figs. 7a and 7b show, in two parts, a flow diagram for the operation of a switching installation according to the present invention.

Fig. 1a shows a simplified diagrammatic illustration of an embodiment of the drive mechanism 1. The bottom of the diagram shows three switching elements in the form of a vacuum circuit breaker 35 with respective fixed contacts 21, 21', 21" and moveable contacts 20, 20', 20", which are surrounded by respective vacuum tubes 19, 19' and 19". The moveable contacts 20 are fixedly connected to respective isolator rods 18, 18', 18". The isolator rods 18 are connected to the drive mechanism 1 via a connection 17, 17', 17", for example a clamping connection. In the state shown in Fig. 1a, the vacuum circuit breakers 35 are in the open position (OFF).
The drive mechanism 1 comprises energy storage means in the form of a closing spring 6, which at one side is secured to a fixed pivot 7 and at the other side is secured to an eccentrically located securing point 9 of an eccentric 8 which is rotatably secured at a fixed rotation point 10. The eccentric 8 can be driven via the shaft 31 and can be moved using a motor or by hand. In the position shown, the closing spring 6 is in an at-rest position, in which the closing spring 6 is at its least stretched.
At its periphery, the eccentric 8 is provided with a cam 11 which interacts with a cam roller 12. The cam roller 12 is connected to first transfer means which comprise a third rod 2 which can be moved substantially in a first direction, which is horizontal in the drawing. This is caused by the third rod 2 being rotatably connected at its ends 23, 23' to an end of a first rod 3 and second rod 3', respectively, the first rod 3 and second rod 3' being of the same length and at their other ends being secured to a fixed pivot 5 and 5', respectively. The first transfer means 12, 2, 3, 3' can move in a horizontal direction between a first position (shown in Fig. 1a) and a second position (shown in Fig. 1b), which are defined by a first stop 24 and second stop 25, respectively, which the connection 23 between first rod 3 and third rod 2 strikes. Stops 24' and 25' of this type are also present for the connection 23' between second rod 3' and third rod 2.
The drive mechanism 1 also comprises second transfer means, which can move substantially in a second direction, which in the drawing is vertical. The second transfer means comprise a sixth rod 13, to which a switching bridge 14 is connected, together, as it were, forming a link which can move up and down. The restriction in the movement is brought about by the fact that a further rod 29 is connected on one side to the sixth rod 13 and on the other side to a fixed pivot 30 at substantially the same height. Furthermore, in the embodiment shown the movement is limited by the fact that two connecting rods 4, 4' are present, rigidly connecting the first and second transfer means to one another. On one side, a fourth rod 4 is connected to one end of the sixth rod 13, while on the other side it is connected to the connecting point 23 between the first and third rods 3 and 2, respectively. On one side, a fifth rod 4' is connected to the other end of the sixth rod 13, and on the other side is connected to the connecting point 23' between second and third rods 3' and 2, respectively.
At the underside, the switching bridge 14 is provided with respective prestressed contact compression springs 15, 15', 15" which interact with respective hammer blocks or anvils 16, 16', 16" which are connected to the clamping connections 17, 17', 17" in order ultimately to move the moveable contacts 20, 20', 20". Furthermore, in the embodiment shown the drive mechanism 1 comprises two compensation springs 28, 28', which are attached to the switching bridge 14. The switching bridge 14 can form an integrated module together with the sixth rod 13, contact compression springs 15, 15', 15" and compensation springs 28, 28'.
Furthermore, a catch spring 26 is rotatably secured to the third rod 2 and in the position shown in Fig. 1a hooks behind a stop 27 and prevents the third rod 2 from moving to the right.
The drawing indicates that the structure of the switching installation can be considered modular: The switching elements of the vacuum circuit breakers 35 are connected via clamping connections 17 to the integrated switching bridge 36 (bridge 14, compensation springs 28, 28', contact compression springs 15, 15', 15", hammer blocks or anvils 16, 16', 16"), which in turn is connected to the drive mechanism 37. In this way, it is also easy for this drive mechanism 37 to be accommodated in a conditioned room which is well sealed off from the environment, so that the mechanism will be less susceptible to faults caused by environmental influences, such as contamination or corrosion.
The operation of the drive mechanism 1 will be described in the text which follows. As has been stated above, Fig. 1a shows the off position, representing a first stable state of the drive mechanism. The closing spring 6 is located at its bottom dead center. The first phase of operation is the energy storage phase, in which the closing spring 6 is tensioned through the shaft 31 in Fig. 1a being rotated through 180°, so that the closing spring 6 moves into its top dead center, in which the maximum energy storage is reached. During this energy storage phase, the shaft 31 is driven by hand or by means of a motor, with the shaft 31 and the manual or motor drive being coupled only in the driving direction. This energy storage phase applies during a rotation of the shaft 31 of at least 180° and at most, for example, 190°. Since the maximum amount of energy stored in the closing spring decreases again after a rotation of 180°, the maximum rotation in the energy storage phase is, inter alia, dependent on the question of whether or not the maximum amount of energy stored in the closing spring 6 has to be made available. In addition, the transition to the next phase is more clearly defined if this maximum rotation is further beyond the dead center of 180°.
The following phase in operation is the energy release phase, in which the energy which has been stored in the closing spring 6 is released as soon as the closing spring 6 passes beyond its top dead center, i.e. at least after 180° rotation of the shaft 31. During this energy release phase, the shaft 31 is driven by the energy which is released, and will continue to rotate together with the eccentric 8 fixed to it and the cam 11. On account of the shape of the cam 11 of the eccentric 8 and the position of the catch spring 26, the cam 11 will firstly push the catch spring 26 out of its stop 27, so that the third rod 2 can move freely to the right. The force of the closing spring 6 acting on the eccentric 8 and the shape of the cam 11 then cause the cam roller 12 to be pushed to the right, so that the assembly comprising first and second transfer means and connecting rods 4, 4' is set in motion until the first transfer means reach the second position, which is defined by the position of the stop 25 or 25'. Obviously, there are also other possible ways of effecting locking and subsequent unlocking of the movement of the first transfer means. During the movement towards the second position, the second transfer means comprising the sixth rod 13 and the switching bridge 14 are moved downwards. The downwardly directed movement is continued until the contacts 20, 21 of the switching elements in the vacuum tubes 19 are closed. Then, the sixth rod 13 moves slightly downwards (approximately 3 mm), with the result that the respective hammer blocks or anvils 16 move slightly upwards and place the contact compression springs 15 under an even greater stress. In the second position, therefore, a sufficiently great contact pressure is produced between the contacts 20, 21. Also, the compensation springs 28, 28' are compressed further by the downward movement of the sixth rod 13.
The on position of the drive mechanism 1 which has now been reached is shown in Fig. 1b and therefore represents the second stable position of the drive mechanism. Correct selection of the dimensions and positions of the various components makes it possible to ensure that the first rod 3 and the vertical part of the switching bridge 14 (or second rod 3' and the vertical part of the switching bridge 14) form a very small angle with one another. This makes it possible, in particular in the final phase of the movement from the off position to the on position, to exert a high downwardly directed force and to lock it using a very small force in relative terms. The locking in this second stable position of the drive mechanism is achieved by blocking the cam roller 12 with the cam 11 from moving back into the first position, i.e. away from the stop 25 or 25'. The cam 11 is in turn blocked such that it cannot rotate further by a trip mechanism, for example as described in more detail below.
As is shown, the closing spring 6 is approximately 15° before its bottom dead center in this locked on position. The low force on the locking before this bottom dead center position and the way in which the locking is implemented make it possible to use the remaining energy stored in the closing spring 6 to move the eccentric and the cam 11 connected to it further under the cam roller 12, thereby eliminating the blocking action.
To move the drive mechanism back out of the on position into the off position, i.e. out of the second stable position into the first stable position of the drive mechanism, therefore, it is necessary to eliminate the blocking which prevents the cam 11 from rotating. Eliminating the blocking allows the eccentric 8 to rotate further and the cam 11 to move onward under the cam roller 12, with the result that, inter alia as a result of the energy stored in the compensation springs 28, 28', the second transfer means will move upwards and in the process force the first transfer means with the cam roller 12 connected thereto to move to the left in the direction of the stop 24, 24'. During this movement of the drive mechanism, the energy in the three contact compression springs 15 is also released. However, the isolation rods 18 only start to move if the hammer blocks or anvils 16 are also carried along. This therefore results in a sudden synchronous movement with a high energy, with the result that the contacts 20, 21 are pulled apart from one another, even if they are stuck to one another, for example by a short-circuit current occurring.
The drive mechanism 1 continues to move until the first position of the third rod 2 is reached once again (against stops 24, 24'). In the last section of the movement of the third rod 2 to the left, the catch spring 26 again latches behind its stop 27, thus preventing unnecessary repeated movement of the contacts of the vacuum circuit breakers 35 towards and away from one another (bouncing). As a result of the force exerted by compensation springs 28, 28', the drive mechanism will remain in this stable first position.
The drive shaft 31 rotates during the movement cycles of the drive mechanism, out of the first stable position via the second stable position back into the first stable position, through 360°, the drive shaft 31, during an energy storage phase, being driven through at least the first 180° in order to supply energy to the energy storage means, after which this energy, during an energy release phase covering the subsequent 165° and the final 15° respectively, is released in order to move the drive mechanism, via the drive shaft 31, into the second or first stable position.
Figs. 2a-c show a simplified illustration of an example of a trip mechanism for releasing the movement of the drive mechanism 1 into the off position. Fig. 2a shows that a further eccentric 51 is secured to the same shaft 31 of the eccentric 8 of the drive mechanism 1. In the embodiment shown, the further eccentric is provided with a catch pawl 57 at a suitable position on its periphery. Obviously, the catch pawl may form an integral part of the further eccentric 51, or alternatively catch pawl 57 may also be secured directly to the shaft 31. In the state shown in Fig. 2a, the catch pawl 57 is prevented from rotating to the right by a hook 58 which is part of a first lever 50. The first lever 50 rotates about a first pivot 52 and is pulled downward by restoring or reset spring 55, which on one side is secured to a fixed pivot 56 and on the other side is secured to the first lever 50. As an alternative, the restoring spring 55 can be omitted, since the force of gravity will also cause the first lever 50 to drop back into the starting position. A second lever 54 rotates about a second pivot 53 and supports the first lever 50 at point 59.
For tripping purposes, the second lever 54 is rotated to the right, for example by means of a push button and a suitable system of levers. In the process, the first lever 50 is also carried along and rotated to the left, with the result that the hook 58 slides off the catch pawl 57 and the eccentric 8 starts to rotate to the right (as a result of the tensile force of the closing spring 6, cf. Fig. 1a) towards the off position (Fig. 2b). When the push button is released, the first and second levers 50, 54 return to their original positions (Fig. 2c).
Figs. 3a-d show simplified sketches of an alternative to the trip mechanism with the possibility of electrical operation. Compared to the embodiment shown in Fig. 2, in this case the second lever 54 and associated pivot 53 have been omitted. Otherwise, components having the same function in Figs. 3a-d are denoted by the same reference numerals as in Figs. 2a-c. It will be clear to the person skilled in the art that the two embodiments may also be combined, so that electrical and mechanical actuation of the trip mechanism is possible.
As shown in Fig. 3 a, the trip mechanism comprises a holding magnet system, comprising a holding plate 60 which in the at-rest position is attracted by a magnetic yoke 63. The holding action of the magnetic yoke can be eliminated by means of a coil 62. A shaft 64, which bears against the first lever 50, is secured to the holding plate 60. As a result of a trip spring 61, which is located between a housing which surrounds the holding plate 60 and yoke 63, and the shaft 64, there will be a force seeking to push the holding plate 60 and shaft 64 upwards, which occurs if a current eliminating the holding action is passed through the coil 62 (Fig. 3b). As a result, the first lever 50 is rotated to the left and the hook 58 will release the catch pawl 57. An electrical energy pulse of, for example, 50 mJ is sufficient to eliminate a holding force which is three times as great as the usual trip spring force, with the result that the first lever 50 will rotate. Obviously, the action of the drive mechanism 1 (see above) rotates the further eccentric 51 approximately 15° further (Fig. 3c). If the drive mechanism 1 is then tensioned by the shaft 31 being rotated further to the right, an upwardly facing section of the first lever 50 will be pushed downward on account of the shape of the further eccentric 51. As a result, the first lever 50 is rotated further to the right and the shaft 64 and holding plate 60 are pressed downward until the holding plate is once again held in place by the yoke 63. The holding force of the holding magnet system is preferably sufficiently great to be able to withstand considerable shock movements (for example >2500 m/s2) in the most unfavorable direction, thus preventing an undesirable effect.
In an alternative embodiment of the electrically actuated locking mechanism shown in Figs. 3a-d, unlike with the passive magnet system having a coil, armature, permanent magnet and holding plate, an active magnet system having a coil and armature is used. The movements required are in this case made by energizing the coil at the correct moment in order to move the first lever 51 out of its at-rest position.
In general, a switching installation as described above comprises for each phase a disconnector enabling parts of the switching installation to be disconnected from one another and/or grounded. The operating mechanism 70 of the disconnectors 73 may form part of or be integrated with the drive mechanism 1 as described above. However, the operating mechanism 70 may also be considered as an independent stand-alone unit.
Fig. 4a shows a diagrammatic side view of a section of a switching installation. The switching installation comprises at least one switching element, such as vacuum circuit breaker 35, a disconnector 73 connected to the circuit breaker 35 on one side, a rail contact 71 and a grounding contact 72. The disconnector 73 can electrically connect the moving contact of the vacuum circuit breaker 35 to the rail contact 71 (first position), can make no connection (second position) or can connect it to the grounding contact 72 (third position). In three-phase installations, these components are present in triplicate for each functional unit. This is shown in the diagrammatic frontal view presented in Fig. 4b.
The drive rod 18 of the vacuum circuit breaker 35 is operated by the drive mechanism 1, top left in Fig. 4a. In one embodiment, the disconnector 73 is electrically connected to the moveable contact of the circuit breaker 35 by means of a sliding contact, so that the moveable contact of the switch can move without one side of the disconnector 73 moving. In the case of the vacuum circuit breaker 35, the disconnector 73 is secured by means of a pivot 74, and at a position located further towards the other end is connected to an insulating disconnector drive rod 76 via a pivot 75. As a result of this disconnector drive rod 76 being moved substantially vertically, the disconnector 73 is moved between the rail contact 71 and grounding contact 72 by rotating about the pivot 74. The disconnector 73 may be designed as any known embodiment which is in practical use. It is preferable for the disconnector to be made from two identical halves which run parallel to one another and at one end surround the sliding contact and at the other end surround the rail or grounding contact, with the pivot 74 being integrated with the sliding contact. This allows a compact, simple and inexpensive structure.
As shown in Fig. 4b, each of the disconnector drive rods 76 is connected to a disconnector bar 82 by means of a pivoting connection 86.
The action of the operating mechanism 70 becomes clearer by referring to Fig. 5a, which shows an enlarged view of section Va in Fig. 4a. A disconnector drive shaft 77 is rotated for the purpose of operating the disconnector 73. A strip 78, which extends radially from the disconnector drive shaft 77, is secured at right angles to the end of the disconnector drive shaft 77. A pivot pin 79, on which a toggle strip 80 is pivoted, is secured to the other end of the strip 78. The toggle strip 80 can move in a plane which is substantially perpendicular to the disconnector drive shaft 77. The other end of the toggle strip 80 is in turn secured to the disconnector bar 82 by means of a pivot pin 81. The disconnector bar 82 is designed, for example with the aid of two guide pins, to execute a substantially linear movement, for example in the vertical direction in the drawing, and this movement is transmitted to the insulating disconnector drive rods 76.
Fig. 5b likewise shows a section of the disconnector mechanism, showing more detail of section Vb in Fig. 4b. The pivot pin 79 is constantly pulled to the right by a tension spring 84 (cf. also Fig. 4b), resulting in two at-rest positions. When the disconnector drive shaft 77 is rotated to the left as seen in the drawing, the further pivot pin 81 (and therefore the disconnector bar 82) will ultimately be located in its lowermost position, with the pivot pin 79 pulled towards a stop 83 by the tension spring 84. It can then be seen from Fig. 4a that the disconnector is then in the rail position. If the disconnector drive shaft 77 is rotated to the right, the disconnector bar 82 will ultimately be located in the top position, in which the disconnector 73 is connected to the grounding contact 72 (grounding position) and in which the pivot pin 79 is in turn pulled towards the stop 83. In an intermediate position, the end of the disconnector 73 is not in contact with the rail contact 71 or the grounding contact 72 (breaking position).
On account of the design with the toggle strip 80, it is possible to obtain a high compressive or tensile force at the end of the movement with a relatively low torque of the disconnector drive shaft 77. As a result of the stop 83 being positioned to the right of the connecting line between drive shaft 77 and further pivot pin 81, it is possible to lock the grounding position or rail position state.
Fig. 6 shows a plan view of the combined drive mechanism according to one embodiment of the present invention. Some components have been omitted for the sake of clarity. A front module 95, which connects the operating side of the switching installation to the drive mechanism 1, is positioned at the front side of the switching installation (the underside in Fig. 6). The operating side comprises an off button 91, which operates the trip mechanism 90 via a switching-off shaft 96 in order to switch off the switching elements of the switching installation. Furthermore, the front side comprises a first opening 92, in which a key can be fitted for the purpose of operating the drive mechanism 1 and the trip/locking mechanism 90 via shaft 31. There is a second opening 93 in order to enable the disconnector mechanism 70 to be operated using a key via disconnector drive shaft 77.
To protect the mechanism from contamination and corrosion, it can be accommodated in a conditioned room. The shaft 31 and disconnector drive shaft 77 are then guided via sealed passages 85 into this conditioned room, in which the actual disconnector drive 70 and drive mechanism 1 are located. Furthermore, a selector 94, which opens the first opening 92 in a first position, closes off both openings 92, 93 in a second position and opens the second opening 93 in a third position, is located between the first and second openings 92, 93.
The orientation of the various components which has been selected and described with reference to the figures creates a drive mechanism which is of extremely compact design yet is nevertheless sufficiently fast and powerful.
As described above, the drive mechanism can be operated by hand. However, it is also possible to use suitable actuators and/or motors to operate the drive mechanism remotely by electrical means and optionally automatically.
The operation of the switching installation according to the present invention will now be explained with reference to the flow diagram shown in Fig. 7a and 7b. In the operating state of the switching installation there are three stable states, characterized by three installation characteristics:

the installation is switched off 101 (switching elements 35 switched off; disconnector 76 in rail position; selector 94 in second position;
the installation is released for operation 102 (switching elements 35 switched off; disconnector 76 in grounding position; selector 94 in second position;
the installation is in operation 103 (switching elements 35 switched on; disconnector 76 in rail position; selector 94 in second position);

From the switched-off state 101 it is possible to move to the switched-on position 103 (decision block 105) by placing the selector 94 in the first position and using the key to rotate the shaft 31 to the right, and then leading the selector 9 back into the second position (block 106).
From the switched-on position 103, it is only possible to change to the switched-off position 101 (decision block 109) by depressing the off button 91 (block 110) or via the trip coil.
From the switched-off state 101, it is possible to move into the released-for-operation state 102 (decision block 107) by placing the selector 94 into the third position and using the key in opening 93 to rotate the disconnector drive shaft 77 to the right, removing the key and returning the selector 94 to position two (block 108).
From the released-for-operation state 102, it is not possible to move directly to the switched-on state 103. It is possible to change from the released-for-operation state 102 to the switched-off state 101 (decision block 111) by once again placing the selector 94 in the third position (block 112), using the key in the opening 93 to rotate the disconnector drive shaft to the left, removing the key and returning the selector 94 to position two (block 113).
Obviously, from the released-for-operation state 102 it is possible to change to one of the four maintenance states (via intermediate block 115), in which any maintenance can be carried out on the installation or on the power supply cable which is connected to the fixed contact of one of the switching elements. In the stable maintenance state, the disconnector 73 is grounded and the selector 94 is in position one. As a result of the selector 94 being placed in position one, access to the operating shaft 31 is released.
This first of all involves moving into the "cable grounded" state 120, by placing the selector 94 in position one, checking that the cable is free of voltage, fitting the key into the first opening 92 and using it to rotate the shaft 31 to the right (block 124). As a result, the switch 35 is closed and the cable is grounded via the switch 35 and disconnector 73.
It is then possible to choose to gain access to the cable connection compartment (decision block 125). This is achieved by opening an access door (block 126). From this state 121 it is possible, for example, to move to a state 122 (decision block 127) in which the cable can be pressed. This is effected by removing the end cap from the cable, putting in place a pressing tool and switching off the switch 35 using off button 91 (block 128). This state 122 is left again (decision block 129), returning to the previous state 121, as a result of the switch 35 being switched on again (using the key in the first opening 92 to rotate the shaft 31 to the right), removing the pressing tool and replacing the end cap (block 130).
It is then possible to return to the operating state "released for operation" or "switched off' (decision block 127) by closing the door (block 131), switching off the switch using off button 91 (block 132). The installation is returned to the released-for-operation state (decision block 133) by placing the selector in position two (block 134 and intermediate block 116). It is possible to return to the "switched off" state (via intermediate block 117) by placing the selector in position three and using the key in the second opening 93 to rotate the disconnector drive shaft 77 to the left, removing the key and placing the selector in position 2 (block 113 in Fig. 7a).
It is also possible to pass from the "cable grounded" state 120 to a "cable grounded and locked" state 123, for example if it is necessary to carry out work on the cable at another location and it is definitely desirable for this cable to be grounded. For this purpose, it is possible for there to be a grounding lock clip which can be pulled out and can be locked using a padlock or the like (block 135). This state 123 can be left again (decision block 136) by removing the padlock and pushing the grounding lock clip back in (block 137). It is then possible to return to either the released-for-operation state 102 or the switched-off state 101 by switching off the switch 35 using off button 91 (block 132).

Claims

A drive mechanism for operating a plurality of switching elements (35) comprising also an operating mechanism (70) for operating a plurality of disconnectors (73) between a first position, in which each of the plurality of disconnectors (73) forms an electrical connection between a pole of an associated switching element (35) and an associated rail contact (71), and a second position, in which each of the plurality of disconnectors (73) does not form an electrical connection to the associated rail contact (71),
in which the operating mechanism comprises
a disconnector drive shaft (77) which can rotate about its axis and has attached to it a radially projecting strip (78), a disconnector bar (82) which can move substantially in a linear direction and is connected, via respective disconnector drive rods (76), to each of the plurality of disconnectors (73), so that is possible for the disconnector drive shaft (77) to rotate between a rail position, which corresponds to a first position, and a breaking position, which corresponds to the second position,
characterised in that to the radially projecting strip (78) a toggle strip (80) is rotatably secured, which toggle strip can move in a plane perpendicular to the disconnector drive shaft (77), the other side of which is rotatably connected to the disconnector bar (82).
The drive mechanism as claimed in claim 1, in which each of the plurality of disconnectors (73) can be moved into a third position, in which each of the plurality of disconnectors (73) forms an electrical connection between the pole of the switching element (35) and a ground contact (72), and furthermore the disconnector drive shaft (77) can be rotated into a grounding position which corresponds to the third position.
The drive mechanism as claimed in claim 1 or 2, in which the disconnectors (73) are designed as two identical halves which run parallel to one another and on the side of the electrical connection to the poles of the switching elements are provided with sliding contacts in which the pivots (74) arc integrated and about which the disconnectors (73) rotate.
The drive mechanism as claimed in claim 1 or 2, in which the connection (79) between the radially projecting strip (78) and the toggle strip (80) is connected to a tension spring (84) which pulls the connection (79) towards a stop (83).
Drive mechanism as claimed in claim 1, 2 or 3, in which the disconnectors (73) move in a movement plane which is perpendicular to the first direction.
Drive mechanism as claimed in one of claims 1 to 5, in which the drive mechanism also comprises a front module (95), having a stop button (91) for operating the trip mechanism, a first opening (92) for driving the shaft (31), a second opening (93) for driving the disconnector drive shaft, and a selector member (94) with three positions, the selector member (94) being designed to open the first opening (92) in a first position, to block the first and second openings (92, 93) in a second position and to open the second opening (93) in a third position.
The drive mechanism as claimed in one of the preceding claims, in which the drive mechanism is accommodated in a conditioned room.
Operation of a switching installation which is equipped with the drive mechanism as claimed in claims 2 and 6, in which the switching installation has a first operating state, in which each of the plurality of switching elements (35) is switched off and each of the plurality of disconnectors (73) is in the first position, and a second operating state, in which each of the plurality of switching elements (35) is switched off and each of the plurality of disconnectors (73) is in the third position, and a third operating state, in which each of the plurality of switching elements (35) is switched on and each of the plurality of disconnectors (73) is in the first position, characterized in that
in each of the operating states the selector member (94) is in position two, and the switching installation changes from the first operating state to the second operating state by the selector member (94) being placed in the position three, the disconnector drive shaft (77) being rotated into the grounding state, and the selector member (94) being reset to position two;
the switching installation is changed from the second operating state to the first operating state as a result of the selector member (94) being placed in position three,
the disconnector drive shaft (77) being rotated into the rail position, and the selector member (94) being reset to position two;
the switching installation is changed from the first operating state to the third operating state as a result of the selector member (94) being placed in position one, the shaft (31) being rotated into the switched-on position of the plurality of switching elements (35), and the selector member (94) being reset to position two; and
the switching installation is moved from the third operating state to the first operating state by actuation of the off button (91).
The operation of a switching installation as claimed in claim 8, in which the drive mechanism may also be in a number of maintenance states, in which the selector member (94) is in the first position.