FR3007190A1 - ELECTRICAL EQUIPMENT COMPRISING A FOLDING ELEMENT AND A MOBILE CONDUCTOR CONNECTED MECHANICALLY - Google Patents

Abstract

Electrical equipment (1) for an electrical line comprising a downstream upstream part (2) and a downstream part (4), a movable conductor (30, 30 ') electrically connected to the upstream part (2), a folding element (50, 50 ') made of at least one electrically insulating material, the folding element (50, 50') being configured to pivot about a fixed axis (13) with respect to the downstream part (4) and driving elements ( 20, 22, 24, 22 ', 24') of the movable conductor (30, 30 '). According to the invention, the movable conductor (30, 30 ') is mechanically connected to the folding element (50, 50') and the driving elements (20, 22, 24, 22 ', 24') are configured to driving both the folding element (50, 50 ') pivotally relative to the downstream part (4) and the movable conductor (30, 30') moving between a closed position and an open position of the apparatus (1).

Description

TECHNICAL FIELD The invention relates to the technical field of electrical equipment for medium, high or very high voltage electrical lines. More specifically, the invention relates to a high-voltage disconnector comprising a folding element configured for the protection and overturning of a live downstream part when the disconnector is in the open position. STATE OF THE PRIOR ART The terms "switches" and "disconnectors" are used to define in this document mechanical connection equipment intended to turn off or de-energize all or part of an electrical installation in accordance with the Commission's definitions. International Electricity 20 (IEC). A high intensity disconnector mainly comprises an upstream part, a downstream part, a movable conductor movably mounted with respect to the upstream part between an open position of the disconnector and a closed position of the disconnector in which the mobile conductor electrically connects the part upstream and the downstream part. The disconnector further comprises drive elements configured to drive the movable conductor moving between the open position and the closed position. During maintenance, personnel may have to intervene near the disconnector. In order to protect this personnel, the switch disconnecting means are provided to cover the downstream part in the open position. These cowling means may in particular comprise a flap 10 for disengaging in the closed position of the disconnector a contact area of the downstream part against which the movable conductor is configured to come into electrical contact. According to a known embodiment, the disconnector comprises an operating wheel separate from the drive elements, the flywheel for driving the flap in displacement so as to cover the downstream part. Therefore, it is necessary for the personnel to move the shutter to cover the downstream part independently of the opening position of the disconnector. This results in an additional risk of human error. Such disconnectors are also quite bulky, have a fairly high cost and are relatively complex to use for personnel working near the disconnector. There is therefore a continuing need for electrical equipment for medium, high or very high voltage electrical lines of limited size, reasonable cost and likely to improve the safety of personnel working near the equipment. DISCLOSURE OF THE INVENTION The invention aims to solve the problems encountered with the solutions of the prior art. The invention is intended in particular to limit the size and improve the safety of personnel working near a switchgear for medium electrical line, high or very high voltage reasonable cost. In this regard, the subject of the invention is an electrical switchgear for medium, high or very high voltage electrical lines, in particular a bar switch, comprising: an upstream and a downstream conductive portion, a movable conductor mechanically and electrically connected to the upstream part, the movable conductor being mounted movable relative to the upstream part between a closed position of the electrical equipment in which the movable conductor is in electrical contact with the downstream part and an open position of the electrical equipment in which the movable conductor is remotely and electrically isolated from the downstream part, a folding element made of at least one electrically insulating material, the folding element being configured to pivot about a fixed axis with respect to the downstream part, driving elements of the mobile conductor, the movable conductor being mechanically connected to the element rab attable and the drive elements being configured to drive both the folding element pivotally relative to the downstream portion and the movable conductor moving between the closed position and the open position. When the apparatus is opened, the folding element made of insulating material pivots automatically to protect the conductive downstream part, especially when it is under tension. Thus, the apparatus requires no additional action from an operator to drive the pivotable member 15 once the apparatus is in the open position. The apparatus according to the invention thus makes it possible to ensure increased safety for personnel working near the apparatus. The apparatus does not have additional means for driving the folding element. Consequently, the costs and the size of the apparatus are reduced. Due to the mechanical connection of the movable conductor with the folding element, the displacement of the movable conductor between the open position and the closed position and the pivoting of the folding element takes place substantially simultaneously. The folding element pivots in particular between a rollover position of the downstream part corresponding to the open position of the apparatus and a decapoting position of the downstream part corresponding to a closed position of the apparatus.

Under the action of the driving elements, the displacement of the movable conductor between the open position and the closed position causes the pivoting element to pivot between the rollover position and the decapotage position. Conversely, the pivoting of the folding element between the rollover position and the decapotage position under the action of the drive elements causes the displacement of the movable conductor between the open position and the closed position. In particular, the drive elements can directly drive the movable element in displacement between the open position and the closed position or directly the pivoting of the folding element between the rollover position and decapotage, depending on whether they are mechanically connected directly to one or the other of these elements. In the closed position, the movable conductor electrically connects the upstream portion and the downstream portion. In the open position, the mobile conductor is remote and electrically isolated from the downstream part. The upstream part and the downstream part are then mechanically and electrically isolated. For example, the upstream portion and the downstream portion are configured to be connected to an electrical installation. In the open position, the electrical installation is at least partially de-energized and / or at least partially de-energized while the current can flow in the closed position. In other words the apparatus can serve as a disconnection element of an electrical installation in the open position and connection element of an electrical installation in the closed position. The invention may optionally include one or more of the following features combined with one another or not: Preferably, the driving elements are configured to drive the folding element indirectly pivotally relative to the downstream portion via the mobile driver.

In this preferred configuration, at least a portion of the driving elements are integral with the movable conductor. The drive elements are then configured to directly drive the movable conductor moving between the open position and the closed position and indirectly the pivotally foldable element between the rollover position and the convertible position by mechanical connection of the driver. mobile and folding element.

Preferably, the movable conductor and the folding element are connected by a groove and a follower pin, the follower pin engaging in the groove. The follower finger and the groove may each be respectively arranged on the folding element or on the movable conductor or at least each of the movable conductor or the folding element being integral with each other. The follower pin is made for example of an electrically insulating material. The groove is preferably a through groove. The groove and the follower pin are mechanically robust guiding means which make it possible to limit the size of the apparatus. They also allow movement of the movable conductor of sufficient amplitude between the open position and the closed position.

However, the connection between the folding element and the movable conductor may comprise, in place of a groove and a follower pin, any other connecting means of the movable conductor to the folding element, configured to allow the opening and closing of the apparatus under the action of the driving elements with both a displacement of the movable conductor between the open position and the closed position and the pivoting of the folding element between the position of rollover and the decapotage position. The apparatus preferably comprises an intermediate segment integral with the movable conductor and preferably forming a bend with the movable conductor, the oblongly movable conductor being mechanically connected to the folding element via the intermediate segment. Preferably, the intermediate segment is of electrically insulating material. The configuration of the apparatus with an oblong mobile conductor and an intermediate segment makes it possible to limit the risks of unintended electrical connection of the upstream part and the downstream part in the open position. Preferably, the downstream portion comprises a closing contact zone with which the movable conductor is in electrical contact in the closed position, the folding element being configured to cover the closing contact zone in the rollover position. The folding element can thus effectively electrically isolate the downstream portion in the open position when it remains under tension. In particular, the folding element can limit the risk of arcing. Preferably, the folding element is configured to be in direct mechanical contact with the closing contact zone in the open position of the apparatus. This allows in particular to reduce the size of the equipment. The downstream portion is preferably at least partially covered by at least one fixed insulating layer outside the closing contact area. The folding element and the insulating layer then form a hermetic insulating protection of the downstream part in the open position. Preferably, the apparatus comprises at least one pair of movable conductors and at least one pair of collapsible elements, the movable conductors and the collapsible members of each pair being arranged substantially symmetrically by planar symmetry with respect to the same plane.

Preferably, the apparatus is substantially symmetrical by planar symmetry with respect to a median plane by the upstream portion and the downstream portion. The two mobile conductors of the apparatus 5 then allow in particular a better electrical connection of the upstream part and the downstream part in the closed position. The drive elements can substantially simultaneously drive each of the two folding elements and substantially simultaneously the two movable conductors when passing from the closed position to the open position. The drive elements comprise, for example, a single motor driving both the mobile moving conductors and the pivotally folding elements. Alternatively, the drive elements may comprise a single steering wheel driving both each movable driver in motion and each pivotally foldable element. The invention also relates to a folding element for an apparatus as defined above, the folding element comprising a projecting portion and a nestable portion, the engageable portion being shaped to come, at least in part, in contact mechanical direct with the downstream part in the open position and to be remote from the downstream part in the closed position, the projecting portion comprising at least one closed groove configured to form a stop for a follower pin. The invention also relates to an assembly comprising a pair of folding elements of the apparatus, each of which is as defined above, in which the folding elements are hinged relative to one another about the axis. fixed pivoting relative to the downstream part, the folding elements of the pair being preferably symmetrical plane plane symmetry comprising the fixed axis. Each folding element of the assembly may include in particular a hinge portion located between the projecting portion and the engageable portion, at which the folding element is configured to pivot relative to the downstream portion.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be better understood on reading the description of exemplary embodiments, given purely by way of indication and in no way limiting, with reference to the appended drawings, in which: FIG. 1 is a perspective view of FIG. electrical apparatus according to one embodiment of the invention; - Figure 2 is a longitudinal sectional view of the apparatus of Figure 1 according to a first preferred embodiment of the invention in the open position; Figure 3 is a top view of the apparatus of Figure 1 in the open position; Figure 4 is a cross-sectional view in half exploded view of the apparatus of Figure 1; Figure 5 is a top view of the apparatus of Figure 1 in the closed position; FIG. 6 shows a set of two foldable elements of the apparatus of FIG. 3. DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS Identical, similar or equivalent parts of the different figures bear the same numerical references so as to facilitate the passage of FIG. one figure to another. The different variants must be understood as not being exclusive of each other and can be combined with one another. FIG. 1 represents an electrical apparatus 1 for a medium, high or very high voltage electrical line. The apparatus 1 may be of various kinds, for example a disconnector or a switch-disconnector. The apparatus 1 comprises an upstream portion 2 and a downstream 4 conductive portion. The upstream 2 and downstream 4 parts are fixed here on a support 6. The apparatus 1 is preferably configured so that in the open position of the apparatus 1, the downstream part 4 can remain under tension while the upstream part 2 is disconnected from any electrical installation. However, according to an alternative embodiment not shown, it is quite possible to configure the apparatus 1 so that the upstream portion 2 remains energized independently of the downstream portion 4 in the open position, while the downstream portion 4 is disconnected from any electrical installation. The terms upstream and downstream are arbitrary and do not necessarily refer to the direction of travel of the electric current. For simplicity, the elements of the apparatus 1 corresponding by planar plane symmetry P bear the same reference with possibly addition of the prime sign ('). The apparatus 1 also comprises a movable conductor 30, 30 'which is mechanically and electrically connected to the upstream part 2. The movable conductor 30, 30' is permanently mechanically and electrically connected to the upstream part 2 in the closed position and in opening position.

The movable conductor 30, 30 'is movably mounted relative to the upstream portion 2 between a closed position of the electrical equipment 1 shown in FIG. 1 and FIG. 5 and an open position of the electrical equipment 1 shown in FIG. in Figures 2 and 3. In the preferred embodiment, the movable conductor 30, 30 'is oblong, such as a bar, a succession of bars or a plate, of conductive material such as metal.

In the closed position, the movable conductor 30, 30 'electrically connects the upstream part 2 and the downstream part 4. The movable conductor 30, 30' is in electrical contact with the downstream part 4 in the closed position. Referring more specifically to Figures 2 and 3, when in the open position, the movable conductor 30, 30 'is remote and electrically isolated from the downstream portion 4. The upstream portion 2 and the downstream portion 4 are then mechanically and electrically isolated.

The movable conductor 30, respectively 30 'is preferably mechanically connected to the upstream portion 2 by a pivot connection at point B, respectively at point B' as shown in more detail in Figure 2. The constituent elements of the connection between the part upstream 2 and the movable conductor 30, 30 'are largely of conductive material to allow permanent electrical contact of the upstream portion 2 and the movable conductor 30, 30'. The mechanical connection of the movable conductor 30, 30 'with the upstream part 2 could be different from that of FIG. 2 as long as it remains compatible with a displacement of the movable conductor 30, 30' between an open position and a position closing the apparatus 1.

Maintenance operations can take place when the electrical equipment 1 is in the open position. It is necessary to electrically isolate the downstream portion 4 of the upstream portion 2 and the movable conductor 30, 30 'in the open position of the apparatus 1 to protect the emergency personnel.

For this purpose, the apparatus 1 also comprises a folding element 50, 50 ', visible in particular with reference to Figures 1 to 5, made in at least one electrically insulating material. The folding element 50, 50 'pivots about a fixed axis 13 relative to the downstream part 4 between a rollover position of the downstream part 4 corresponding to the open position of the apparatus 1 and a decapotage position of the downstream part 4 corresponding to a closed position of the apparatus 1. In the rollover position, the folding element 50, 50 'is configured to cover at least a part 4a, 4a' of the downstream part 4. The part downstream 4 is then mechanically protected by the folding element 50, 50 '. It is also protected from any electrical contact with the movable conductor 30, 30 'and the upstream part 2 by the folding element 50, 50'. In the uncoupling position, the folding element 50, 50 'is configured to allow electrical contact of the movable conductor 30, 30' and the downstream part 4. In this position, with reference to FIG. 1 and FIG. the folding element 50, 50 'is preferably substantially folded on the downstream part 4 symmetrically with respect to the main axis 3 of the apparatus 1. In the preferred embodiment, the downstream part 4 comprises a zone of closing contact 4a, 4a 'with which the movable conductor 30, 30' is in electrical contact when in the closed position. The folding element 50, 50 'is configured to cover the closing contact zone 4a, 4a' in the rollover position and to disengage it in the decapoting position. Preferably, the downstream portion 4 is at least partially covered by at least one fixed insulating layer 9, 9 ', visible in FIG. 2, in a fixed protection zone 4b, 4b' of the downstream part outside the closing contact area 4a, 4a '. The fixed protection zone 4b, 4b is complementary to the closing contact zone 4a, 4a '. These two zones preferably make it possible to impart a quasi-hermetic electrically insulating protection to the downstream part 4 in the open position of the apparatus 1. In the preferred embodiment, the folding element 50, 50 'is in mechanical contact directly with the closing contact zone 4a, 4a 'when it is in the rollover position. According to a not shown embodiment of the apparatus 1, the folding element 50, 50 'is not in direct mechanical contact with the downstream part 4 when it is in the rollover position by isolating the downstream part 4 of the movable conductor 30, 30 'and the upstream portion 2. The folding element 50, 50' is preferably oblong such as a flap. It will be described in more detail with reference to Figure 6. The folding element 50, 50 'is mechanically connected to the movable conductor 30, 30'. In the preferred embodiment, the movable conductor 30, 30 'and the folding element 50, 50' are mechanically connected by a groove 55, 57, 5 ', 57' and a follower pin 33, 35, 33 ', 35 ', the finger engaging in the follower pin 33, 35, 33', 35 'may be mounted integral with the folding element 50, 50' or respectively mounted to the movable conductor 30, 30 '. The groove 55, 57, 55 ', 57' is then mounted relative to the follower pin 33, 35, 33 ', 35' integral with the movable conductor 30, 30 'or respectively integral with the folding element 50, 50'. The groove 55, 57, 55 ', 57' is preferably a through groove. According to an alternative embodiment not shown, the groove is blind. The follower pin 33, 35, 33 ', 35' is made for example of an electrically insulating material. The connection of the movable conductor 30, 30 'with the folding element 50, 50' may also be different in nature if it remains compatible with a displacement of the movable conductor 30, 30 'between the open position and the closed position. and pivoting substantially simultaneously of the folding element 50, 50 'between the rollover position and the decapotage position. In the preferred embodiment, the apparatus 1 comprises an intermediate segment 32, 32 'for connecting the movable conductor 30, 30' and the folding element 50, 50 'in a connection zone 39. The intermediate segment 32, 32 'is in particular integral with the movable conductor 30, 30' of follower 33, 35, 33 ', 35' groove 55, 57, 55 ', 57'. The oblong shape with which it forms an elbow. The intermediate segment 32, 32 'is for example fixed at one end of the movable conductor 30, 30' forming substantially a right angle with this end.

The intermediate segment 32, 32 'is fixed to the mobile conductor 30, 30' by any means falling within the general knowledge of those skilled in the art. The intermediate segment 32, 32 'is also configured to be mechanically connected to the folding element 50, 50' via the groove 55, 57, 55 ', 57' and the follower pin 33, 35, 33 ', 35 '. In Figure 2, the follower pin 33, 35, 33 ', 35' is mounted on the intermediate segment 32, 32 '. According to an alternative embodiment not shown, the intermediate segment comprises the groove 55, 57, 55 ', 57' in which is engaged the follower pin 33, 35, 33 ', 35' located on the folding element 50, 50 . The intermediate segment 32, 32 'is preferably made of electrically insulating material, including the same material as the folding element 50, 50'. According to the preferred embodiment, the apparatus 1 comprises a plurality of movable conductors 30, 30 'and several folding elements 50, 50', i.e. at least one pair of movable conductors 30, 30 'and at least a pair of folding elements 50, 50 '. The movable conductors 30, 30 'and the folding elements 50, 50' of each pair are arranged substantially symmetrically by plane symmetry 30 with respect to the same median longitudinal plane P of the apparatus 1 visible in FIG. 1 and in FIG. The folding elements 50, 50 ', the movable conductors and the guide means 33, 33', 55, 55 ', 57, 57' 32, 32 'of the preferred embodiment are also symmetrical with respect to a second plane of transverse symmetry Q visible in Figure 4. The apparatus 1 also comprises driving elements 20, 22, 24, 22 ', 24' of the movable conductor 30, 30 '. The driving elements 20, 22, 24, 22 ', 24' are configured to drive both the folding element 50, 50 'pivotally with respect to the downstream part 4 and the movable conductor 30, 30' on the move between the closed position and the open position, preferably substantially simultaneously through the mechanical connection of the movable conductor 30, 30 'and the folding element 50, 50'. The driving elements 20, 22, 24, 24 'comprise, for example, a primary driving element 20, a transmission element 22, 22' and a hinge part 24, 24 '. In the preferred embodiment, the primary driving element 20 is a motor. The motor 20 has an axis of revolution 23 which is preferably included in the plane P. In general, the apparatus 1 comprises only one motor 20 in order to reduce the bulk. However, the motor 20 may have any other suitable configuration. The motor 20 can in particular be any motor adapted to set in motion the assembly comprising a movable conductor 30, 30 'and the associated folding element 50, 50'. The choice of the engine 20 is general knowledge of the skilled person.

According to an alternative embodiment not shown, the primary driving element 20 may be an operating wheel or any usual means known to those skilled in the art for both to actuate the movable conductor 30, 30 'moving between the open position and the closed position and the corresponding folding element 50, 50 'pivoting about the fixed axis 13 with respect to the downstream part 4, preferably substantially simultaneously, via the mechanical connection of the movable conductor 30, 30 'and the folding element 50, 50'. The fixed axis 13 is preferably located on the downstream portion 4. It is also included in the plane of symmetry P. The articulation piece 24 is for example a cross member secured to the movable conductor 30, 30 '. The transmission element 22 mechanically connects the main driving element 20 to the movable conductor 30, 30 'or to the folding element 50, 50'. The transmission element 22 is here a curved rod.

In the preferred embodiment shown in FIGS. 1 to 5, the drive elements 20, 22, 24, 22 ', 24' are configured to directly drive the movable conductor 30, 30 'and to drive the folding element 50, 50 'pivotally with respect to the downstream portion 4 indirectly through the 30 of the movable conductor 30, 30' and the mechanical connection of the movable conductor 30, 30 'and the folding element 50, 50'. The displacement of the movable conductor 30, 30 'from the open position to the closed position thus causes the pivotable element 50, 50' to pivot along a circle-shaped path R1, R '1. The movable conductor 30, 30 'drives the folding element 50, 50' pivotally from the cowling position in which it mechanically and electrically protects the downstream part 4 and the decapoting position in which it allows the electrical contact of the mobile conductor 30, 30 'with the downstream part 4. As an alternative not shown, the drive elements 20, 22, 24, 22', 24 'directly drive the folding element 50, 50' pivotally in relation to the downstream part 4 between the rollover position and the uncoupling position and drive the movable conductor 30, 30 'indirectly in displacement 20 between the open position and the closed position via the mechanical connection of the movable conductor 30 , 30 'and the folding element 50, 50'. Referring more specifically to FIG. 6, each folding element 50, 50 'of the apparatus 1 comprises a protruding portion 54, 54' and a nestable portion 52, 52 '. The engageable portion 52, 52 'is shaped to come, at least partly, to cover the contact part 4a with a direct mechanical contact of the interlocking portion 52, 52' with the downstream part 4 in the rollover position and to be able to distance of the downstream part 4 in the decapoting position. The protruding portion 54, 54 'comprises at least one groove 55, 57, 55', 57 'closed configured to form at least one stop for the follower pin 33, 35, 33', 35 ', in particular a stop at each end longitudinal groove 55, 57, 55 ', 57'. The folding elements 50, 50 'of a pair of folding elements 50, 50' of the apparatus 1 are articulated with respect to each other about the fixed axis 13 around which they are configured to pivot, the folding elements 50, 50 'of the pair being preferably symmetrical by plane plane symmetry P comprising the fixed axis 13. Each folding element 50, 50' comprises a hinge portion 58, 60 located between the projecting portion 54 , 54 'and the engageable portion 52, 52'. The folding element 50, 50 'is in particular configured to pivot at the hinge portion 58, 60 with respect to the downstream portion 4.

Of course, various modifications may be made by those skilled in the art to the invention which has just been described without departing from the scope of the disclosure of the invention. 30

Claims (10)

REVENDICATIONS1. Electrical apparatus (1) for medium, high or very high voltage electrical line 5, in particular a bar switch (1), comprising: a downstream upstream part (2) and a downstream part (4), a movable conductor (30, 30 ') 10 mechanically and electrically connected to the upstream part (2), the movable conductor (30, 30') being movably mounted relative to the upstream part (2) between a closed position of the electrical equipment (1) wherein the movable conductor (30, 30 ') is in electrical contact with the downstream part (4) and an open position of the electrical equipment (1) in which the movable conductor (30, 30') is at remote and electrically isolated from the downstream part (4), a folding element (50, 50 ') made of at least one electrically insulating material, the folding element (50, 50') being configured to pivot about an axis fixed (13) with respect to the downstream part (4), - drive elements (20, 22, 2 4, 22 ', 24') of the movable conductor (30, 30 '), characterized in that the movable conductor (30, 30') is mechanically connected to the folding element (50, 50 ') and that the drive members (20, 22, 24, 22 ', 24') are configured to drive both the folding member (50, 50 ') pivotally with respect to the downstream portion (4) and the movable conductor (30, 30 ') moving between the closed position and the open position. 2. Apparatus (1) according to the preceding claim, characterized in that the drive elements (20, 22, 24, 22 ', 24') are configured to drive the folding element (50, 50 ') indirectly in pivoting relative to the downstream portion (4) via the movable conductor (30, 30 '). Apparatus (1) according to one of the preceding claims, characterized in that the movable conductor (30, 30 ') and the folding element (50, 50') are connected by a groove (55, 57, 55 ', 57') and a follower pin (33, 35, 33 ', 35'), the follower pin (33, 35, 33 ', 35') engaging in the groove (55, 57, 55 ', 57 '). 4. Apparatus (1) according to any one of the preceding claims, characterized in that it comprises an intermediate segment (32, 32 ') integral with the movable conductor (30, 30') and preferably forming an elbow with the driver. movable conductor (30, 30 ') of oblong shape is mechanically connected to the folding element (50, 50') via the intermediate segment (32, 30 '). 32 '). 5. Apparatus (1) according to the preceding claim, characterized in that the intermediate segment (32, 32 ') is electrically insulating material. Apparatus (1) according to one of the preceding claims, characterized in thatthe downstream part (4) comprises a closing contact area (4a, 4a ') with which the movable conductor (30, 30') is electrical contact in the closed position, the downstream part (4) being at least partly covered by at least one fixed insulating layer (9, 9 ') outside the closing contact area (4a, 4a') and in that that the folding element (50, 50 ') is configured to cover the closing contact zone (4a, 4a') in the open position of the apparatus (1). 7. Apparatus (1) according to any one of the preceding claims, characterized in that the folding element (50, 50 ') comprises a projecting portion (54, 54') and a nestable portion (52, 52 '). , the engageable portion (52, 52 ') being configured to come, at least partly, to cover the downstream part (4) in the open position of the apparatus (1) and to be at a distance from the downstream part (4) ) in the closed position of the apparatus (1), the projecting portion (54, 54 ') comprising at least one closed groove (55, 57, 55', 57 ') configured to form at least one follower finger abutment (33, 35, 33 ', 35'). 8. Apparatus (1) according to any one of the preceding claims, characterized in that the apparatus (1) comprises at least one pair of movable conductors (30, 30 ') and at least one pair of folding elements (50 , 50 '), the movable conductors (30, 30') and the folding elements (50, 50 ') of each pair being arranged substantially symmetrically by plane symmetry with respect to the same plane (P). Foldable element (50, 50 ') for an apparatus according to any one of the preceding claims, characterized in that the folding element (50, 50') comprises a projecting portion (54, 54 ') and a portion nestable portion (52, 52 ') being shaped to come, at least in part, in direct mechanical contact with the downstream part (4) in the open position and to be at a distance from the downstream part (4) in the closed position of the apparatus (1), the projecting portion (54, 54 ') comprising at least one closed groove (55, 57, 55', 57 ') configured to form at least one follower finger stop (33, 35, 33 ', 35'). 10. An assembly comprising a pair of foldable elements (50, 50 ') which are each according to the preceding claim, the two foldable elements (50, 50') being preferably symmetrical by flat plane symmetry (P), characterized in that that each folding element (50, 50 ') is hinged relative to the other folding element (50, 50') of the pair around the fixed axis (13) of pivoting with respect to the downstream part (4). 25