AU2011253702B2

AU2011253702B2 - Interlock device designed to secure access to the cable box of an electric cubicle and electric cubicle comprising one such device

Info

Publication number: AU2011253702B2
Application number: AU2011253702A
Authority: AU
Inventors: Patrick Maquet
Original assignee: Schneider Electric Industries SAS
Current assignee: Schneider Electric Industries SAS
Priority date: 2010-11-30
Filing date: 2011-11-28
Publication date: 2014-10-09
Anticipated expiration: 2031-11-28
Also published as: EP2458607A1; EP2458607B1; BRPI1107045A2; RU2011148620A; CN102543511B; ES2428494T3; CN102543511A; FR2968144B1; AU2011253702A1; FR2968144A1

Abstract

INTERLOCK DEVICE DESIGNED TO SECURE ACCESS TO THE CABLE BOX 5 OF AN ELECTRIC CUBICLE AND ELECTRIC CUBICLE COMPRISING ONE SUCH DEVICE. The present invention relates to an interlock device designed to secure access to 10 the cable box of an electric cubicle, said cubicle comprising at least one electric switchgear apparatus in series with earthing means of the cables, said cubicle being connected line-side to an electric power supply system and load-side to at least one cable, the cable or cables being housed in a cable box comprising a rear panel, a bottom panel, a top panel separating the cable box from the compartment 15 housing the switchgear apparatus and the earthing means, two side panels and a door. This device is characterized in that it comprises a case (11) housing a lock (12) and a counter lever (13), said case (11) being designed to be fixed onto the inner surface of a panel (21) of the cable box (3), said lock (12) collaborating on the one hand with a door (4) and on the other hand with a rod system (17) for 20 locking the door commanded by the shaft (7) of the earthing device, so that commanding earthing of the cables results in unlocking of the door (4), said counter lever (13) collaborating on the one hand with the door (4) and on the other hand with a rod system for locking the selector (24) so as to prevent movement of the selector (8) to a position allowing opening or closing of the switchgear 25 apparatus when the door is not in the closed position. 30 Fig.2. I&I II. 8 25a 27 25 2 oll 25b 61* a26a 6 c 18a 26d -18b 3 - 19a - 19d c23 17 24 30d 19 -- 26 1 1 9e 3 13b 3c19b \14 1 15 121 13a

Description

Pool Section 29 Regulation 3.2(2) AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: Invention Title: Interlock device designed to secure access to the cable box of an electric cubicle and electric cubicle comprising one such device The following statement is a full description of this invention, including the best method of performing it known to us: 111ABAU/0610 INTERLOCK DEVICE DESIGNED TO SECURE ACCESS TO THE CABLE BOX OF AN ELECTRIC CUBICLE AND ELECTRIC CUBICLE COMPRISING ONE SUCH DEVICE. 5 The present invention relates to an interlock device designed to secure access to the cable box of an electric cubicle, said cubicle comprising at least one electric switchgear apparatus in series with earthing means of the cables, said cubicle being connected line-side to an electric power supply system and load-side to at 10 least one cable, the cable or cables being housed in a cable box comprising a rear panel, a bottom panel, a top panel separating the cable box from the compartment housing the switchgear apparatus and the earthing means, two side panels and a door, said device comprising means for allowing opening of the above-mentioned door only if earthing of the cables is effective, means for preventing closing of the 15 switchgear apparatus so long as the door is not present and locked, and means for allowing reconnection of the earthing means to the line when the door is open but preventing closing of the switchgear apparatus when said door is open, said cubicle comprising a selector mechanically connected to the switchgear apparatus and to the earthing means, said selector being able to be actuated by an operator 20 and being movable between two positions respectively a position enabling operation of the opening and closing shaft of the switchgear apparatus and a position not enabling this operation. Two types of interlock devices designed to secure access to the cable box of a 25 medium-voltage electric cubicle are known, these devices being able to be placed in these two categories depending on the location of the locking systems, the latter being able to be located either inside or outside the cable box. In the case where the interlock system is located outside the cable box, the principle consists in mechanically locking the door from the outside. This device is 30 often achieved by means of a stop added onto the door and designed to move so as to be housed in a lock fixed onto the cubicle. The lock is then controlled directly or indirectly by the earthing device via a connecting rod system. The main drawback of these systems resides in the fact that they are accessible from the outside and are therefore liable to be defrauded or vandalised.

2 These systems therefore have to be oversized so as to stand up to the outside environment. Furthermore, they are salient from the cubicle, are difficult to integrate in the latter and are generally unaesthetic. In the case of the system internal to the cable box, the principle consists in 5 mechanically locking the door from the inside by means of removable stops located inside the cable box, said stops being controlled directly or indirectly by the earthing device via a pass-through connecting rod system. The major drawback of these devices is that they penetrate into the cable box and therefore generate dielectric stresses. 10 The present invention solves these problems and proposes an interlock device that is both sufficiently compact not to generate dielectric stresses and sufficiently robust to fulfil the interlock function, as well as a medium-voltage electric cubicle comprising one such device. 15 For this purpose, one object of the present invention is to provide an interlock device of the above-mentioned kind, said device being characterized in that it comprises a case housing a lock and a counter lever, said case being designed to be fixed onto the inner surface of a panel of the cable box, said lock collaborating 20 on the one hand with the door and on the other hand with a rod system for locking the door controlled by the shaft of the earthing device, so that commanding earthing of the cables results in the door being unlocked, said counter lever collaborating on the one hand with the door and on the other hand with a locking rod system of the selector so as to prevent movement of the selector to a position 25 allowing opening or closing of the switchgear apparatus when the door is not in the closed position. According to a particular feature, the lock comprises an elongate part mounted sliding through respectively two parts folded to form a bracket of the case, said 30 elongate part comprising a first part around which a spring is fitted and a second part collaborating with the rod system for locking the door, said spring being fitted between one of the parts folded into a bracket and the above-mentioned second part of the elongate part, the spring biasing the lock to a retracted position.

3 According to another feature, this second part comprises an opening designed to collaborate with an angled part formed at the end of the connecting rod called second rod of the rod system for locking the door, this rod system moving through 5 the above-mentioned opening against the return force of the spring in a substantially perpendicular direction to the direction of movement of the lock, the spring biasing the lock to a retracted position when the rod system moves away from the opening. 10 According to another feature, this counter lever is mounted articulated with respect to the case and comprises a first end designed to collaborate with a finger provided on the door and a second end collaborating with the rod system for locking the selector. 15 According to another feature, the above-mentioned two rod systems pass through the above-mentioned opening. According to another feature, this device comprises means for fixing the door to the cable box, said means comprising securing means securedly affixed to the 20 cable box or to the door, said securing means collaborating with at least one aperture belonging to the door, respectively to the cable box, so as to enable the door to slide with respect to the cable box from a position in which said door is partially facing the switchgear apparatus and the cable box to a position in which said door is located completely facing the cable box, a position enabling said door 25 to be locked, fixing of the door being performed by the first of all pressing the door against the cable box and then moving it downwards until it collaborates with the above-mentioned securing means, a position in which said door can be locked. According to another feature, the above-mentioned rod system for locking the 30 door comprises a first rod comprising a first end secured in rotation to the earthing shaft and a second end connected in articulated manner to one of the ends of a flat rod called second rod twisted through 900, the other end of which rod operates in conjunction with a lock, said rod being twisted so that this rod comprises two 4 parts extending along two planes forming an angle of substantially 90* between them, the first plane extending substantially perpendicularly to the opening/closing shaft of the switchgear apparatus and to the earthing shaft and substantially parallel to the rear wall of the cable box, and the second plane extending 5 substantially parallel to the depth of the cable box and therefore to its side panels. According to another feature, the rod system for locking the selector comprises a rod called third rod articulated with respect to a support called first support of the switchgear apparatus and comprising a first end collaborating with the selector 10 and a second end mounted articulated with respect to one of the ends of a rod called fourth rod twisted through 9 0 0, so that this rod comprises two parts extending along two planes forming an angle of substantially 90* between them, the first plane extending substantially perpendicularly to the opening/closing shaft of the switchgear apparatus and to the earthing shaft and substantially parallel to 15 the rear wall of the cable box, and the second plane extending substantially parallel to the depth of the cable box and therefore to its side panels. According to another feature, the first end of the rod called third rod comprises a notch collaborating with a shank belonging to the selector and extending 20 substantially parallel to the opening and closing shaft and to the earthing shaft, According to another feature, in the position called "door absent", the rod system for locking the selector is moved by gravity to a locking position of the selector in which it collaborates with the above-mentioned shank. 25 According to another feature, the rod called third rod is mounted articulated on a support called second support, said second support being riveted onto the above mentioned support called first support of the switchgear apparatus. 30 According to another feature, the first rod of the rod system for locking the door is fixed onto the earthing shaft by clipping.

5 According to another feature, all the parts of the locking device i.e. the case, lock, counter lever, door presence finger, rod system for locking the door and rod system for locking the selector, are made from simple sheet metal parts. 5 It is a further object of the present invention to provide a medium-voltage electric cubicle comprising an interlock device comprising the above-mentioned features taken either alone or in combination. But other advantages and features of the invention will become more clearly 10 apparent in the following detailed description which refers to the appended drawings given for example purposes only and in which: -Figure 1 is a schematic representation illustrating a medium-voltage electric cubicle according to the invention, 15 -Figures 2 to 8 are partial perspective views illustrating an interlock device according to the invention implemented in a medium-voltage cubicle respectively in different positions of this device, 20 -Figure 2 represents the above-mentioned device, the switch of the cubicle being closed, the earthing device being connected to the line and the door being closed and locked, -Figure 3 represents the above-mentioned device, the switch of the cubicle being 25 open, the earthing device being connected to the line and the door being closed and locked, -Figure 4 represents the above-mentioned device, the switch of the cubicle being open, the earthing device being earthed and the door being closed and unlocked, 30 -Figure 5 represents the above-mentioned device, the switch of the cubicle being open, the earthing device being earthed and the door being open, 6 -Figure 6 represents the above-mentioned device, the switch of the cubicle being open, the earthing device being connected to the line and door being open, -Figure 7 represents the above-mentioned device, the switch of the cubicle being 5 open, the earthing device being earthed and the door being open, -Figure 8 represents the above-mentioned device, the switch of the cubicle being open, the earthing device being earthed and the door being closed, 10 -Figure 9 is a partial perspective view illustrating fixing of a door presence indicating finger on the door, -Figure 10 is a partial perspective view illustrating fixing of a case comprising the lock on the door, 15 -Figure 11 is a partial perspective view illustrating fixing of the rod system for locking the selector and of the rod system for locking the door on a support of the cubicle, and 20 -Figure 12 is a perspective view separately illustrating the door presence indicating finger, the case housing the lock, the rod system for locking the door and the rod system for locking the selector. In figure 1, a medium-voltage electric cubicle C can be seen electrically connected 25 line-side to a high-voltage electric power system R and load-side to cables c, said cubicle comprising an electric switchgear apparatus such as a switch or circuit breaker 1 connected in series with an earthing device 2, said switchgear apparatus being connected line-side to the high-voltage electric power system and load-side to the earthing device, said earthing device being connected load-side to 30 said cable box 3, said door 4 being accessible by means of a door. In figures 2 to 8, the cubicle comprises in a manner known as such a support 5, called first support, with respect to which there are fitted with rotation a pole shaft 6 via which the contacts of the switchgear apparatus can be closed or opened, 7 and a shaft 7 belonging to the earthing device, said shaft being able to be operated by an operator between two positions respectively earthing the cables or connecting the cables to the line. The cubicle also comprises a selector 8 mechanically connected to the control 5 shaft or pole shaft, said selector being able to be moved to one of two positions, respectively a first position in which the selector 8 enables the control shaft 6 to be operated and a second position in which the selector prevents operation of this shaft. In a manner also known as such, the cubicle C comprises an interlock device 10 comprising means for preventing access to the cable box so long as earthing of the cables is not effectively performed, means for preventing closing of the switchgear apparatus so long as the door of the cable box is not present and locked, and means for enabling the earthing device to be reconnected to the line with the door open, but preventing closing of the switch or circuit breaker when 15 this door is open. According to the invention, the interlock device according to the invention comprises three assemblies. The first assembly comprises a locking device 9 of the selector 8 designed to be controlled by the door 4, the second assembly comprises a locking device 10 of 20 the door designed to be controlled by the secondary shaft of the earthing device and the third assembly comprises a case 11 housing a lock 12 and a counter lever 13, said counter lever 13 being designed to collaborate with a finger 14 provided on the door 4 designed to indicate the presence or absence of the door. The door presence indicating finger, the case and the two locking devices are successively 25 represented from left to right in figure 12. As can also be seen in these figures 2 to 8, the door 4 of the cable box 3 is fixed onto the cable box by fixing means comprising securing means 15 integral to the cable box, said securing means collaborating with an aperture 16 provided in the door so as to enable the door to slide between a first position in which the door is 30 partially facing the switchgear apparatus and facing the cable box and a position in which the door is completely facing the cable box and collaborates with the above-mentioned securing means 15. Fixing of the door is thus performed by first of all pressing the door 4 against the cable box 3 and moving it downwards until it 8 collaborates with the above-mentioned securing means 15, a position in which said door can be locked, as will be able to be explained in the following. The locking device of the door 10 comprises a rod system, said rod system comprising a first rod 18 comprising a first end 18a secured in rotation to the 5 earthing shaft 7 and a second end 18b connected in articulated manner to one 19a of the ends of a flat rod 19 called second rod, twisted through 9 0 *, the other end 19b of which rod is designed to collaborate with a lock 12, said rod 19 being twisted in such a way that this rod comprises two parts 19c,19d extending in two planes forming an angle of substantially 90* between them, the first plane 10 extending substantially perpendicularly to the opening/closing shaft 6 of the switchgear apparatus and to the earthing shaft 7 and substantially parallel to the rear wall 20 of the cable box, and the second plane extending substantially parallel to the depth of the cable box and therefore to its side panels 21. The free end of the twisted rod 19 comprises a bevelled part 19c designed to collaborate 15 with an opening 23 provided in the lock 12 as will be explained in the following. The rod system 24 locking the selector 8 comprises a rod called third rod 25 articulated with respect to said support 5 of the switchgear apparatus 1 and comprising a first end 25a collaborating with the selector 8, and a second end 25b mounted articulated with respect to one 26a of the ends of a rod called fourth rod 20 26 twisted through 90*, so that this rod comprises two parts 26c,26d extending in two planes forming an angle of substantially 90* between them, the first plane extending substantially perpendicularly to the opening/closing shaft 6 of the switchgear apparatus and to the earthing shaft 7, and substantially parallel to the real wall 20 of the cable box, and the second plane extending substantially parallel 25 to the depth of the cable box and therefore to its side panels 21. The first end 25a of the rod called third rod 25 comprises a notch 27 collaborating with a shank 28 belonging to the selector 8 and extending substantially parallel to the opening shaft 6 and to the earthing shaft 7, the selector being mounted with rotation with respect to the support called above-mentioned first support 5 30 between the above-mentioned two positions. The free end of the rod called fourth rod 26 collaborates with the above-mentioned counter lever 13 fitted in the case 11 as will be explained in the following.

9 As can be particularly seen in figure 11, the rod called third rod 25 of the rod system 17 for locking the door is mounted articulated on a support called second support 29 riveted onto the support called above-mentioned first support 5 of the switchgear apparatus 1, whereas the first rod 18 of the rod system 17 for locking 5 the door is fixed to the earthing shaft 7 by clipping means 32. The interlock device according to the invention also comprises the above mentioned case 11 designed to be fixed onto the inner surface of a side panel 21 of the cable box, as illustrated in figure 10. Said case houses a lock 12 and a counter lever 13. This lock 12 comprises an elongate part 30 mounted sliding via 10 its two opposite ends respectively through two parts folded to form a bracket 11a,11b of the case 11, said elongate part comprising a first part 30c around which a spring 31 is fitted, and a second part 30d collaborating with the rod system 17 for locking the door, said spring 31 being fitted between one 11 a of the parts folded to form a bracket and the above-mentioned second part 30d of the 15 elongate part 30, the spring 31 biasing the lock 12 to a retracted position. This second part 30d comprises an opening 23 designed to collaborate with an angled part 1 9e formed at the free end of the rod called second rod 19 of the rod system 17 for locking the door, this rod system moving through the above 20 mentioned opening against the return force of the spring in a direction substantially perpendicular to the direction of movement of the lock, the spring biasing the lock to a retracted position when the rod system moves away from the opening. The rod system 24 for locking the selector, the free end of the fourth rod 26 of 25 which collaborates with the counter lever 13, is also fitted through this opening 23. The counter lever 13 is mounted articulated with respect to the case 11 and comprises a first end designed to collaborate with a part forming a finger 14 fixed onto the door, as illustrated in figure 9, and a second end collaborating with the 30 rod system 24 for locking the selector. Operation of the interlock device according to the invention will be described in the following with reference to the figures.

10 In figure 2, the pole shaft 6 is in the closed position, the position of the selector 8 towards the left side of the switchgear apparatus with respect to figure 2 having enabled this movement, and the earthing device 2 is connected to the line. The shank 28 of the selector is released from the notch of the rod system 17 for 5 locking the door. The door 4 is in the closed and locked position, locking being performed by inserting the lock 12 in an opening 33 of the door 4, against the force of the spring 31 which is pressing via one 31a of its ends on the door and via its opposite end 31b on the lock, this movement of the lock having been caused by movement of the rod system 17 for locking the door through the opening 23, by 10 cooperation of the angled shape 19e of the rod system with the above-mentioned opening. In this position, the door presence finger 14 biases the counter lever 13 upwards, which has the effect of driving the rod called third rod 25 in a counterclockwise rotational movement. In this position, access to the cable box is prevented so long as earthing of the cables is not effective. 15 In figure 3, the switch is open. The pole shaft 6 is in the open position, which has driven the selector 8 to the earthed position. In figure 4, the switch is open and the secondary earthing shaft 7 is in the earthed position. This has caused upward movement of the second rod 19, releasing the latter from the above-mentioned opening 23. This results in the spring 31 biasing 20 the lock 12 to a retracted position enabling opening of the door 4. In figure 5, the door is open, which has had the effect of releasing the counter lever 13 from the door presence indicating finger, which enables the rod system 24 locking the selector to move down through the opening 23 of the lock, due to the effect of gravity. This movement of the rod system 24 results in clockwise 25 rotational movement of the third rod 25 and engagement of the notch 27 with the shank 28 of the selector 8, thereby preventing operation of the selector 8. This position of the selector does not prevent the earthing shaft 7 from being reconnected to the line, as is the case in figure 6, for example when performing cable injection tests. This reconnection to the line has the effect of moving the 30 second rod 19 downwards through the opening 23, which has the effect of making the lock 12 move out of the case 11. This results in it becoming impossible to refit the door. Refitting of the door 4 requires re-earthing of the earthing device so as to bias the lock 12 to a retracted position, as illustrated in figure 7. This position 11 allows reconnection of the earthing device to the line, but does not allow closing of the switch or circuit breaker 1. Refitting of the door then causes rotation of the counter lever 13, which has the effect of causing upward movement of the fourth rod 26 and of releasing the shank 28 from the notch 27 as illustrated in figure 8. 5 This releasing does not yet enable operation of the pole shaft, and in particular closing of the switchgear apparatus, as the cables c first have to be reconnected to the line. An interlock device providing total safety for the operator without penalizing 10 ergonomy has therefore been achieved according to the invention. The device according to the invention is thus robust and compact, and can be easily integrated in the cable box via the front panel, in any phase of life, does not require any adjustment and comprises a minimum of parts. Dimensional constraints are circumvented by a concept of a compact lock 15 combined with a rod system that is also compact. This compactness is obtained by flat rods twisted through 90* enabling their space occupation to be optimized without changing plane (in the depthwise direction as far as control is concerned and in the widthwise direction as far as the cable box is concerned). 20 This extra-flat lock can be housed in the thickness of the flank of the cable box. This small space occupation means that users are not hampered when performing operations in the cable box to fit connectors, perform maintenance operations, cable testing, etc. The small space occupation also makes it possible not to generate any dielectric stress. Equipping a cable box with an interlock device does 25 not penalize its dielectric performances. Furthermore, this sub-assembly is totally accessible from the front panel. It is thus very easy to equip a cubicle. This is particularly interesting in the case of juxtaposed enclosures (cubicle assembly). It enables operations to be performed directly via the front of the part concerned without dismantling adjacent elements. 30 Fitting of the different elements is performed in simple and quick manner solely by riveting and clipping without any screws or bolts, this operation not requiring any adjustment from the operator.

12 The system is further a positive safety system. In the rest state, the interlock is in the "door absent" position in which it is impossible to operate the switch or circuit breaker. This state is obtained naturally by gravity. Likewise, the spring only serves the purpose of biasing the lock and therefore of releasing the door. In case 5 of malfunctioning of the spring, the door therefore remains in the locked position. Furthermore, locking the selector is called engaging, the more force is applied to the selector the more firmly the system locks. The whole of the interlock system is achieved from assembly of simple sheet metal parts. 10 These parts are obtained by "traditional" folding and do not require any specific process or precise tolerance. The lock is made from two sheet metal parts simply secured to one another by a spring. These parts are assembled in extremely simple and quick manner without any tools. 15 Once the lock assembly has been fitted on the cubicle, there is no possible access. Any risk of damage is thereby avoided. All this contributes to simple and quick implementation, without any particular tools, for a relatively low cost. The invention applies to any compartment of an electric cubicle comprising an 20 operating shaft and an earthing shaft and presenting a controlled access to the live parts via a door. The invention is naturally not limited to the embodiment described and illustrated which has been given for example purposes only. 25 On the contrary, the invention extends to encompass all the technical equivalents of the means described as well as combinations thereof if the latter are performed according to the spirit of the invention.

Claims

1. An interlock device designed to secure access to the cable box of an electric cubicle, said cubicle comprising at least one electric switchgear apparatus in series with earthing means of the cables, said cubicle being connected line side to an electric power supply system and load-side to at least one cable, the cable or cables being housed in a cable box comprising a rear panel, a bottom panel, a top panel separating the cable box from the compartment housing the switchgear apparatus and the earthing means, two side panels and a door, said interlock device comprising means for allowing opening of the above-mentioned door only if earthing of the cables is effective, means for preventing closing of the switchgear apparatus so long as the door is not present and locked, and means for allowing reconnection of the earthing means to the line when the door is open but preventing closing of the switchgear apparatus when said door is open, said cubicle comprising a selector mechanically connected to the switchgear apparatus and to the earthing means, said selector being able to be actuated by an operator and being movable between two positions respectively a position enabling operation of the opening and closing shaft of the switchgear apparatus and a position not enabling this operation, characterized in that said interlock device further comprises a case housing a lock and a counter lever, said case being designed to be fixed onto the inner surface of a panel of the cable box, said lock collaborating on the one hand with the door and on the other hand with a rod system for locking the door controlled by the shaft of the earthing device, so that commanding earthing of the cables results in the door being unlocked, said counter lever collaborating on the one hand with the door and on the other hand with a rod system for locking the selector so as to prevent movement of the selector to a position allowing opening or closing of the switchgear apparatus when the door is not in the closed position.

2. An interlock device according to claim 1, wherein the lock comprises an elongate part mounted sliding respectively through two parts folded into a bracket of the case, said elongate part comprising a first part around which a spring is 14 fitted and a second part collaborating with the rod system locking the door, said spring being fitted between one of the parts folded into a bracket and the above mentioned second part of the elongate part, the spring biasing the lock to a retracted position.

3. An interlock device according to claim 2, wherein this second part comprises an opening designed to collaborate with an angled part formed at the free end of the rod called second rod of the rod system for locking the door, this rod system moving through the above-mentioned opening against the biasing force of the spring in a direction substantially perpendicular to the direction of movement of the lock, the spring biasing the lock to a retracted position when the rod system moves away from the opening.

4. An interlock device according to any one of claims 1 to 3, wherein the counter lever is mounted articulated with respect to the case and comprises a first end designed to collaborate with a finger provided on the door and a second end collaborating with the rod system for locking the selector.

5. An interlock device according to claim 3 or 4, wherein the above mentioned two rod systems pass through the above-mentioned opening.

6. An interlock device according to any one of claims 1 to 5, further comprising means for fixing the door onto the cable box, said means comprising securing means integral to the cable box or to the door, said securing means collaborating with at least one aperture belonging to the door, respectively to the cable box, so as to enable sliding of the door with respect to the cable box from a position in which said door is partly facing the switchgear apparatus and the cable box to a position in which said door is totally facing the cable box, a position enabling locking of said door, fixing of the door being performed by first pressing the door against the cable box and then moving it downwards until it collaborates with the above-mentioned securing means, a position in which said door can be locked. 15

7. An interlock device according to any one of claims 1 to 6, wherein the above-mentioned rod system for locking the door comprises a first rod comprising a first end secured in rotation to the earthing shaft and a second end connected in articulated manner to one of the ends of a flat rod called second rod twisted through 900, the other end of which rod operates in conjunction with a lock, said rod being twisted so that this rod comprises two parts extending along two planes forming an angle of substantially 900 between them, the first plane extending substantially perpendicularly to the opening/closing shaft of the switchgear apparatus and to the earthing shaft and substantially parallel to the rear wall of the cable box, and the second plane extending substantially parallel to the depth of the cable box and therefore to its side panels.

8. An interlock device according to any one of claims 1 to 7, wherein the rod system for locking the selector comprises a rod called third rod articulated with respect to a support called first support of the switchgear apparatus and comprising a first end collaborating with the selector and a second end mounted articulated with respect to one of the ends of a rod called fourth rod twisted through 900, so that this rod comprises two parts extending along two planes forming an angle of substantially 900 between them, the first plane extending substantially perpendicularly to the opening/closing shaft of the switchgear apparatus and to the earthing shaft and substantially parallel to the rear wall of the cable box, and the second plane extending substantially parallel to the depth of the cable box and therefore to its side panels.

9. An interlock device according to claim 8, wherein the first end of the rod called third rod comprises a notch collaborating with a shank belonging to the selector and extending substantially parallel to the opening and closing shaft and to the earthing shaft.

10. An interlock device according to claim 9, wherein in the position called "door absent", the rod system for locking the selector is moved by gravity to a locking position of the selector in which it collaborates with the above-mentioned shank. 16

11. An interlock device according to any one of claims 8 to 10, wherein the rod called third rod is mounted articulated on a support called second support, said second support being riveted onto the above-mentioned support called first support of the switchgear apparatus.

12. An interlock device according to any one of claims 1 to 11, wherein the first rod of the rod system for locking the door is fixed onto the earthing shaft by clipping.

13. An interlock device according to any one of claims 1 to 12, wherein the case, lock, counter lever, door presence finger, rod system for locking the door and rod system for locking the selector, are made from sheet metal.

14. A medium-voltage electric cubicle comprising an interlock device according to any one of the foregoing claims. SCHNEIDER ELECTRIC INDUSTRIES SAS WATERMARK PATENT AND TRADE MARKS ATTORNEYS P35241 AUO0