EP2479769A1 - Medium-voltage cutting device including a vacuum tube - Google Patents

Abstract

The device has a vacuum cartridge (6) branch-connected with line-side and load-side stationary contacts (1, 2) and a rotating/sliding main movable contact (3) of a main electric circuit. The cartridge has a rod (10) passing via an enclosure (7) and supporting a movable contact (9) of the cartridge. A vacuum cartridge operating mechanism is actuated by the main contact, and actuates the rod. The mechanism has a rigid rotating rocker arm (12) connecting the rod and the main contact. The arm has articulation regions around which the arm is rotated during opening and closing operations of circuit.

Description

TECHNICAL AREA

The object of the invention is an electric switch or circuit breaker, particularly suitable for medium voltage, and comprising a vacuum interrupter; the term "medium voltage" (MV) is used in its usual acceptance, ie for a voltage that is greater than 1000 volts AC and 1500 volts DC but does not exceed 52000 volts AC and 75000 volts AC. volts in direct current.

STATE OF THE ART

Such devices must ensure the shutdown and isolation of electrical circuits. Their base element is a movable main contact on the electrical circuit so as to have a closed state and an open state of the circuit. Cutting the circuit can however be problematic because of the appearance of an arc crossing the movable contact even when it has been opened. Vacuum bulbs are therefore often added as a bypass to the main contact, so as to pass the current as soon as the main contact is open, which avoids the formation of an arc. When the vacuum bulb is opened in its turn, the circuit is cut reliably since the arc goes out immediately in the vacuum of the bulb.

The control mechanism by which the vacuum interrupter is open is advantageously actuated by the movable contact itself during part of its opening stroke so that the operator has only one command to perform and the opening of the Vacuum bulb is synchronized with that of the main circuit with a very small delay. The documents US-A-5,168,139 , FR-A-2,731,434 and FR-A-2,937,786 describe vacuum bulbs or switches incorporating them.

Various control mechanisms have already been proposed in the prior art, but they present a certain complication which involves an economic disadvantage and can reduce their reliability. One of the reasons is that the moving main contact makes a reverse path by closing the electric circuit, and so it intercepts the control device as it had done during the opening of the circuit, which is not possible without precaution since the control device, generally recalled to a state invariable by a spring, does not have a reversible operation. The interception during the reclosing of the circuit is thus prevented by a retraction of the main contact or the control device, for example by constructing it with a unidirectional articulation (as in the third document above), which complicates the switch and can impair its reliability.

SUMMARY OF THE INVENTION

An object of the invention is therefore to simplify such switches and / or circuit breakers, more generally electrical cutoff devices, in particular medium voltage.

In a general form, the invention relates to a device that is particularly suitable for medium-voltage shutdown, having a bypass vacuum bulb on a main electrical circuit that can be opened or closed by a movable main contact, the vacuum interrupter having a rod passing through an envelope and carrying a movable contact of said vacuum interrupter, the switch further comprising a control mechanism of the vacuum interrupter actuated by the main contact and actuating the rod and comprising a rotary pendulum connecting the rod and the mobile main contact. The balance is rigid and comprises two hinge regions around which it rotates respectively during the openings and closings of the main electrical circuit.

The known complex balance, composed of two parts hinged together, is replaced by a unitary balance and mounted flexibly, without fixed points of articulation. The use of a hinge that could be described as oscillating between two fixed points in the direction of rotation of the pendulum allows it to fully intercept the main moving contact in one direction and to be moved by it, but of retract in front of him in the other direction of movement.

In most embodiments, the mechanism also comprises a rod return spring to an invariable state, which can be connected, for example, to a fixed structure of the switch or balance, or between the envelope and the rod of the vacuum bulb.

In an important design, the balance is articulated to the rod at one of said articulation regions. The control mechanism may then comprise, at the other of said articulation regions, a fixed axis, and a portion of the balance provided with an oblong slot in which the axis plays when the balance wheel rotates around said one of the regions of 'joint. In another design, the rod is fixed rigidly to the balance and flexible; the hinge regions are then advantageously points of contact of the balance to fixed parts of the switch, the balance being connected only to the rod in a state not solicited by the moving main contact; said fixed parts of the cut-off device can belong to a sleeve fixed to the vacuum bulb and surrounding the rod, and are situated on either side of the rod.

Electrical conduction through the bypass to the vacuum interrupter can be provided by the pendulum, or possibly by a conductive switching tab electrically connected to the moving contact of the vacuum interrupter, and extending to a free end superimposed approximately at a free end of the beam which intercepts the movable main contact, the movable main contact rubbing on the free end of the switching tab.

When this leg exists, the rocker can also rub on the switch tab with a greater resistance than a force exerted by the return spring; this design makes it possible to establish two stable states of the switch at different positions of the beam in the absence of bias by the movable main contact.

The movable main contact can be rotating or sliding.

BRIEF DESCRIPTION OF THE FIGURES

• les figures 1, 2, 3, 4, 5, 6 et 7 illustrent une première réalisation de l'invention et diverses étapes de l'ouverture et de la fermeture du circuit ;
• les figures 8, 9 et 10 illustrent de même une autre réalisation de l'invention;
• et les figures 11, 12, 13, 14, 15 et 16 illustrent une troisième réalisation de l'invention.

Some embodiments of the invention will now be described for purely illustrative purposes in connection with the following figures:

• the Figures 1, 2 , 3, 4 , 5, 6 and 7 illustrate a first embodiment of the invention and various stages of opening and closing the circuit;
• the figures 8 , 9 and 10 likewise illustrate another embodiment of the invention;
• and the Figures 11, 12 , 13, 14 , 15 and 16 illustrate a third embodiment of the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

As described in figure 1 , the switching device, here a switch, comprises a main circuit consisting of an upstream fixed contact (1), a downstream fixed contact (2), a main movable contact (3) connected to the downstream fixed contact ( 2) by a hinge (4) and having a free end (5) for connecting with the free end of the upstream fixed contact (1) to establish a closed state of the circuit, shown in this figure 1 . The vacuum bulb (6) forms a bypass of the main circuit. It comprises an envelope (7), a fixed contact (8) electrically connected to the upstream fixed contact (1) through the envelope (7), a movable contact (9) present in the envelope (7), located at the end a rod (10) whose opposite end extends out of the casing (7) forming a hinge and also with a rocker (12), and the movable contact (9) touches the fixed contact (8) in the closed state of the vacuum interrupter (6), shown here. The tightness of the interior of the casing (7) is preserved by a bellows (13) surrounding the rod (10), one end of which is sealed against an edge of the casing (7) and whose other end is tightened on the rod (10) close to the movable contact (9).

A switch tab (14) comprises a handle (15) extending parallel to the end of the fixed upstream contact (1) from the end of the bellows (13), which it touches, up to the free end ( 5) of the main movable contact (3), and an enlarged end, spatula-shaped (16), extending from the handle (15) perpendicular to it towards this free end (5) at a short distance from it. The rocker (12) also comprises two portions (17, 18) forming an angle between them, the first of which, extending in front of the end of the casing (7), bears the articulation (11), a pin for attaching a spring (22) stretched between the rocker (12) and a point (23) of a fixed structure (19) of the switch, and a light (20) in which slides an axis (21) also belonging to the fixed structure (19); the second portion (18) extends in front of the switching tab (14), and their free ends are approximately aligned perpendicularly to the plane of the figure and the main circuit, in the state of closure of the light bulb. empty (6). The switching tab (14) and the rocker (22) may be in frictional contact or not.

As illustrated in figure 2 , the opening of the electric circuit is effected by the rotation of the main movable contact (3) by a handle not shown, and the recovery with the upstream fixed contact (1) gradually ceases. The main movable contact (3), however, reaches the end of the balance (12) before, so that the electric current is directed gradually through the shunt occupied by the vacuum bulb (6), which avoids the creation electric arc between the contacts (1, 3). The electrical conduction is effected by contacts (8, 9), the rod (10), and the balance (12) if all the parts are conductive; it can also be effected through the contacts (8 and 9), the bellows (13) which must then be conductive, and the switching tab (14) if it rubs on the balance (12) or the movable contact principal (3).

The stage of figure 3 represents the opening of the switch: the main movable contact (3) is completely separated from the upstream fixed contact (1), and it has started to push back the balance (12), which is nevertheless retained at its opposite end by the spring (22), so that it tilts about the axis (21). The rod (10) is pulled out and separates the movable contact (9) from the fixed contact (8). The electric current is then cut in the vacuum bulb (6). When the rotation of the main movable contact (3) is continued, the end of the rocker (12) escapes from the main movable contact (3) ( figure 4 ), and can come back in place by closing the vacuum bulb (1) ( figure 5 ), the circuit remaining open. However, it is possible, according to a variant shown in figure 6 , that a friction between the rocker (12) and the switching tab (14) maintains that one at the position where the main movable contact (3) pushed it, keeping the vacuum bulb (6) open , which can improve sectioning.

The figure 7 illustrates the reclosing of the circuit. The main movable contact (3) is brought back in a reverse movement, passes in front of the switching tab (14) by rubbing on it or not and intercepts the end of the beam (12) by rotating it in the opposite direction. When the contacts (8, 9) touch, the rod (10) however remains motionless and the rotation of the balance (12) continues around the articulation (11), which remains stationary. The spring (22) is then stretched, and the rocker (12) moves in front of the axis (21), which slides in the oblong slot (20). This continues until the balance (12) escapes the interception of the free end (5). The switch then returns to the state of the figure 1 .

In another embodiment ( figure 8 ), the switching tab (14) is absent, as are the axis (21), the light (20), and the hinge (11). The rocker (12), however, remains united to the rod - now (24) - of the vacuum bulb (6), which consists of a conductive rod having a certain flexibility and which is embedded in the balance (12). A spring (25) is positioned around the rod (24) inside the bellows (13) and recalls the contacts (8, 9) in the closed position. A sleeve (26) is finally established outside the envelope (7) of the vacuum bulb (6), around the rod (24) and stops at a short distance from the balance (12).

The opening of the circuit begins as before by a rotation of the main movable contact (3) ( figure 9 ), which is intercepted by the free end of the balance (12); the rocker (12) is moved by pulling the rod (24) against the spring (25), bending it somewhat because of the rotation caused by the main movable contact (3), and a pivot point (27) eventually appears by contact of one end of the beam (12) with a portion of the sleeve (26). But the balance (12) returns in place thanks to the elasticity of the rod (24) of the spring (25) when the main movable contact (3) has exceeded.

The reclosing of the circuit is illustrated in the figure 10 the main movable contact (3) tilts the rocker (12) in the opposite direction, again producing a bending of the rod (24) in the opposite direction, and another pivot point (28) is formed between the balance (12) and the sleeve (26) opposite the point (27) above on the sleeve (26). The contacts (8, 9) can be slightly separated.

In another embodiment ( figure 11 ), the main movable contact - now (30) - is movable in translation and rubs on the downstream fixed contact (29) during its displacement. The vacuum bulb (6) and the control device are approximately identical to the first embodiment, except that the ends of the balance - now (31) - and the switching tab - now (32) - have proportions modified to take account of the interception with the main movable contact (30): it extends parallel to the rod (10), moves in this direction, and intercepts the balance (31) and the switching tab (32) by a projection (33) which it carries.

The figure 12 illustrates the beginning of the opening of the circuit. One end (34) of the main movable contact (30) gradually leaves a flange (35) electrically connected to the upstream fixed contact (1), while the projection (33) slides against the end of the switching tab (32). ) and gradually transfers the current into the branch of the vacuum interrupter (6). The figure 13 illustrates the disconnection of the main circuit and the opening of the vacuum interrupter which follows soon after, the projection (33) pushing the end of the pendulum (31). When the opening of the circuit is complete, the rocker (31) has been thus turned to escape the projection (33) and has returned to its position ( figure 14 ), or, ( figure 15 ) on the contrary not returned completely in place but keeps the contacts (8 and 9) open, thanks to a friction between him and the switching tab (32). When the circuit is closed, the main movable contact (30) rotates the balance (31) in the other direction and therefore forces, as in the first embodiment, a movement of the axis (21) in the light (20) consecutive tilting the balance (31) about the axis (30), the contacts (8 and 9) being kept closed, by stretching the spring (22). When the protrusion (33) has passed the balance (31) in the closing direction, the switch returns to the state of the figure 11 .

Claims (14)

Power cut-off device, particularly suitable for medium voltages, having a vacuum interrupter (6) branched to a main electric circuit (1, 2, 3; 1, 30, 29) which can be opened or closed by a main contact mobile (3), the vacuum bulb (6) having a rod (10, 24) passing through a casing (7) and carrying a movable contact (9) of said vacuum bulb (6), the device further comprising a mechanism for controlling the vacuum interrupter (6), actuated by the main contact (3) and actuating the rod (10; 24) and comprising a rotating balance (12, 31) connecting the rod (10, 24) and the contact mobile main (3, 30), characterized in that the rocker (12, 31) is rigid and comprises two hinge regions (12, 21; 27, 28) around which it rotates respectively during the openings and the closures of the circuit main electrical system (1, 2, 3; 1, 30, 29). A power cut-off device according to claim 1, wherein the control mechanism comprises a spring (22, 25) for returning the rod (10, 24) to an invariable state. A power cut-off device according to claim 2, wherein the spring (22) is connected to a fixed structure (19) of the device and to the rocker (12). A power cut-off device according to claim 2, wherein the spring (25) is disposed between the casing and the stem of the vacuum bulb (6). Power cut-off device according to one of claims 1 or 2, wherein the rocker (12, 31) is articulated to the rod (10, 24), to one of said hinge regions. A power cut-off device according to claim 5, wherein the control mechanism comprises, at the other of said articulation regions, a fixed axis (21) and a portion of the beam provided with an oblong slot (20) in which axis plays when the rocker rotates around said one of the articulation regions. A power cutoff device according to any one of claims 1 to 3, wherein the rod (10) is rigidly attached to the pendulum and flexible. A power cut-off device according to any one of claims 1 to 4 or 7, wherein the hinge regions are points of contact of the balance to fixed parts (27, 28) of the device, the balance being connected only to the rod to a state not solicited by the movable main contact. A power cut-off device according to claim 8, wherein said fixed portions of the current cut-off device belong to a sleeve (26) attached to the vacuum interrupter and surrounding the rod, and are located on either side of the the stem. A power cut-off device according to any one of claims 1 to 9, wherein the contact between the beam and the movable main contact is made either by friction or by a system of articulated grippers. A power cutoff device according to any one of claims 1 to 9, further comprising a conductive switching tab (14) electrically connected to the moving contact of the vacuum interrupter and extending to a free end superimposed approximately at a free end of the beam which intercepts the movable main contact, the movable main contact rubbing on the free end of the switching tab. A power cutoff device according to claims 2 and 10, wherein the rocker also rubs on the switch tab, with a greater resistance than a force exerted by the return spring. A power cutoff device according to any of claims 1 to 11, wherein the movable main contact is rotating. A power cutoff device according to any of claims 1 to 11, wherein the movable main contact is slidable.

Images