FR2710452A1 - High voltage switch with rotating arc. - Google Patents

Abstract

Rotary arc switch (1) comprising a fixed contact (2), a movable contact (3), a sealed casing (4) forming an interrupting chamber (5) which surrounds the fixed and movable contacts and a device (6) for rotating the arc around said fixed contact. According to the invention, the switch further comprises a cooling means (14) which is arranged in the interrupting chamber and which consists of a plurality of plane rings (15) arranged parallel to each other and spaced apart from each other. others so as to constitute between them a plurality of annular spaces (18).

Description

_- (2710452

  ARC HIGH VOLTAGE HIGH VOLTAGE SWITCH

  The present invention generally relates to a rotating arc switch and more particularly to a high-voltage rotating arc switch comprising a fixed contact, a movable contact, a sealed external envelope forming a chamber of

  cut and a device for rotating the arc fixedly mounted on the fixed contact.

  High voltage arc switches are widely used, especially in high voltage circuit breakers, and manufacturers have been concerned

  constant attempt to limit the detrimental effects of the cut-off arc.

  Numerous devices for rotating the electric arc have already been proposed, these devices being mounted generally on or around the fixed contact of the switch and generally being constituted by a fixed annular electrode surrounding

  the fixed contact and connected to it by a coil.

  Another known way to limit the harmful effects of the electric arc has been to provide in the arc chute a device for cooling the electric arc. Yet another known way to limit the harmful effects of the electric arc has been to provide in the breaking chamber a device for deflecting and / or cooling the cutoff gas so that it produces a blowing effect or extinguishing the arc more efficient. FR-A-2,371,762 discloses a rotating arc switch comprising rings (8) which serve to cool the electric arc and to produce a rolling effect of the gas. These rings each have the form of a flat washer whose inner diameter or diameter of the central hole is slightly greater than an outer diameter of a flared portion of the movable contact (11), so that the gas produced in the chamber of cut is forced to pass longitudinally in the space between the outer diameter of the movable contact and the inner diameter of the central hole of each ring (8), o a rolling effect of the gas. On the other hand, in such a known switch, the electric arc substantially follows the inner edge of the rings and it follows that the rings are used for cooling the arc but the ionized gas produced is not enough.

  cooled. The breaking capacity of such a circuit breaker is limited.

  EP-A-0 064 425 discloses a rotating arc switch in which, within an arc extinguishing chamber, there is provided a wall (44) which is cylindrical sleeve-shaped and which is concentrically housed in the arc-extinguishing chamber which has a substantially annular shape, said wall (44) serving to guide the gas flow so as to cause it to circulate within the chamber of arc extinguishing in order to improve the arc extinguishing function obtained by this circulation of the gas. This wall (44) is constituted by a single piece, and therefore has only two opposite cylindrical surfaces in contact with the gas, these opposite surfaces being located substantially along the longitudinal central axis of the switch and not providing a contact area with gas

  large enough to cause significant cooling of this gas.

  In addition, in the known switches of the types corresponding to the documents of the prior art mentioned above, a phenomenon of appearance of "post-arc currents" generally occurs. This well known phenomenon occurs when the conventional switch operates to cut a current whose intensity is close to the maximum allowable intensity for this switch, for example, for a high voltage installation, a maximum permissible intensity of 30 kA. These post-arc currents are electric currents that can last several tens of milliseconds after the opening of the electrical contacts, without these currents.

  lead to failure failure. These currents are then called "post currents".

  It is an object of the present invention to provide a high-voltage rotating arc switch to provide increased cutoff power without

  increased dimensions of the switch.

  Another object of the present invention is to provide such a switch that can further maintain its improved performance while reducing the dimensions

of the switch.

  Another object of the present invention is to provide such a switch further to prevent the occurrence of "post-recovery currents" when the switch operates to cut an electric current whose intensity is

  close to the maximum allowable value for this switch.

  The invention therefore relates to a rotating arc switch comprising a fixed contact, a movable contact, a sealed envelope forming a breaking chamber which surrounds the fixed and movable contacts and a device for rotating the arc around said

fixed contact.

  According to an essential characteristic of the invention, the switch further comprises a cooling means which is arranged in the breaking chamber and which is constituted by a plurality of plane rings arranged substantially parallel to each other and spaced apart from one another. to form between them a plurality of annular spaces. According to a particular embodiment of the invention, each of said rings is in the general form of a substantially flat and thin disk-shaped plate provided with a central hole whose diameter is greater than the largest external diameter of the contact. mobile and in that the rings are arranged to surround the movable contact being substantially centered on the longitudinal central axis of said switch. According to another embodiment of the invention, the maximum spacing distance between the fixed and movable contacts is equal to or less than the sum of the minimum distance between said cooling means and the fixed contact and the distance

  minimum between said cooling means and the fully open movable contact.

  These objects, features and benefits, as well as others of this

  invention will be better understood in the detailed description of embodiments of

  the invention, illustrated by the appended figures among which: Figure 1 is a simplified longitudinal sectional view of a first embodiment of a switch according to the present invention; Figure 1A shows a profile view of a ring of the cooling device; Figure 2 is a simplified longitudinal sectional view of another embodiment of a switch according to the invention; Figure 3 is a simplified longitudinal sectional view of yet another embodiment of a switch according to the invention; and FIG. 4 is a simplified longitudinal sectional view of yet another

  embodiment of a switch according to the invention.

  FIG. 5 shows a partial half-view in section and on an enlarged scale of a

variant embodiment.

  In Figure 1, there are essential parts constituting a high voltage switch rotating arc 1 which can be used, for example, in high voltage circuit breakers. This switch 1 is designed to include certain improvements, which will be described later, which allow to give the switch a breaking capacity greater than 30 kA, while reducing the dimensions of the switch. Such a switch can for example be easily designed so that it can perform

  current cuts of the order of 40 to 50 kA, without inducing post-arc current.

  The switch 1 according to the present invention comprises a fixed contact 2, a movable contact 3, a sealed envelope 4 which forms inside a breaking chamber 5 which surrounds the fixed and movable contacts 2 and a device 6 to turn the electric arc. The device 6 can be any conventional device which can generally comprise a fixed annular electrode which surrounds the fixed contact 2 and which is connected thereto by a coil 7. In the figure, the movable contact 3 is represented in its position of closing the switch in the upper part of the figure and in its open position of the switch in the lower part of the figure. The movable contact 3 is in the general form of a hollow tube 8 which is centered on the longitudinal central axis 9 of the switch 1. The movable contact 3 moves back and forth along this central axis longitudinal 9. The fixed contact 2 is in the general form of a ring and the movable contact 3 is also in the general form of a ring of substantially identical diameter. A set of connecting pieces 10, 11, 12 is fixedly and sealingly connected to the fixed contact 2 and the movable contact 3 to the sealed envelope 4. The fixed contact 2 is connected to a terminal or to an external electrical connection piece 13 and the movable contact 3 is secured to a mechanical actuation device (not shown) for controlling its longitudinal reciprocating movement, and is electrically connected to a terminal or an electrical connection piece (not shown) . The parts 10, 11, 12, 13 and the other parts mentioned above and not shown in Figure 1 may be of a conventional design well known for such a high voltage switch arc

  rotating 1, and these parts are therefore not described in more detail here.

  An object of the present invention is to provide inside the breaking chamber 5 a gas cooling device 14 which has several functions but whose essential function is to cause rapid cooling of the cutoff gases produced during the formation of the rotating electric arc that appears when opening the movable contact 3. The gas cooling device 14 is in the form of a rigid assembly having an annular piece fixed inside the breaking chamber 5 in a manner centered on the longitudinal central axis 9 of the switch 1. Preferably, the sealed envelope 4 has a generally cylindrical shape such that the breaking chamber 5 delimited outwards by the inner wall of the sealed envelope 4 and inwardly through the outer wall of the tube 8 for supporting the movable contact 3, is a chamber having an annular shape. The gas cooling device 14 is arranged concentrically inside the

  breaking chamber 5 which also has a generally annular shape.

  Without departing from the general scope of the present invention, it would be possible to design a switch 1 whose breaking chamber would have a shape different from an annular shape, for example a shape whose cross-sectional section would be square, and in which case, the gas cooling device 14 could also have a shape whose cross sectional section would be square. Other forms

  could also be envisaged without departing from the scope of the present invention.

  The gas cooling device 14 according to the present invention is constituted by a plurality of rings 15. Each ring 15 is in the form of a substantially flat washer, that is to say that each ring 15 has a rim outer ring 16 and a central hole limited by an inner rim 17. The rings 15 are preferably arranged parallel to each other and are spaced from each other by a constant or variable distance, so that the rings 15 constitute between a plurality of annular passages 18 which extend substantially radially with respect to the longitudinal central axis 9 of the switch 1. The rings 15 can be held in place in the position described above with the aid of any support pieces. 19 which allow the rings 15 to be fixedly connected to a rigid part 11 of the switch 1. In the embodiment shown in FIG. felt only one of these support pieces 19, this piece 19 being in the general form of a threaded rod whose left end is anchored to the connecting piece 11 and which extends substantially longitudinally to the 5. The rings 15 have holes formed in correspondence with the support parts 19 and the rings 15 are arranged in a stacked manner on the support parts 19 which pass through the holes of the rings 15. Spacers are arranged between each adjacent ring 15 so as to ensure the spacing of the rings 15 with each other, this spacing making it possible to constitute the different

  annular spaces 18 described above.

  The operation of the gas cooling device 14 will now be described. In the embodiment shown in Figure 1, the gas cooling device 14 is in the form of a rigid annular piece which is constituted by the plurality of rings 15 and which is limited inwards by the flanges 17 rings 15 and outwards by the flanges 16 of the rings 15. Therefore, the gas cooling device 14 is generally in a generally annular shape whose central hole has a larger diameter than the outer diameter of the moving contact. 3. The ring 15A which is located closest to the movable contact 2 is arranged at a relatively small longitudinal distance relative to the fixed contact 2 and the distance between its inner flange 17 and the outer flange of the fixed contact 2 is indicated on the Figure 1 by the D1 mark. The ring 15B situated opposite to the ring 15A is located either substantially in line with the moving contact 3 when the latter is in the open position, or further back relative to the moving contact 3 when the latter is in position. it is in the open position, as shown in the lower part of Figure 1. In the latter case, when the movable contact is in the open position, one of the rings 15 located in an intermediate position between the end rings 15A and 15B constitute the ring whose inner rim 17 is located closest to the outer rim of the movable contact 3 in the open position and the distance that separates the inner rim 17 and the outer rim of the contact mobile 3 defines a distance D2 which is shown in Figure 1. When the movable contact 3 is in the open position, the distance between the movable contact 3 of the fixed contact 2 is a distance C. Preferably, the cooling device the gas 14 is designed and arranged in the breaking chamber 15 so that the sum of the distances D1 and D2 is substantially equal to or greater than the distance C. When the movable contact 3 opens, a rotating electric arc occurs. which is established substantially in the shortest path between the fixed contact 2 and the movable contact 3 and which generates a hot cut gas. This cutoff gas passes radially through the radial spaces 18 of the gas cooling device 14 and this gas is effectively cooled in contact with the rings 15. Preferably, the width of the annular spaces 18, that is to say the distance separating two consecutive rings 15, is relatively small, for example between 0.5 mm and 5 mm and the number of annular spaces 18 is relatively large, for example between 5 and 20. The cutoff gas is channeled through the spaces annular 18 which extend substantially radially relative to the longitudinal central axis 9 and this gas is therefore both energetically cooled and caused to move radially relative to the general direction of the path taken by the electric arc which is form between the fixed contact 2 and the movable contact 3. All of these phenomena has the consequence that the cutoff gas passes radially with a high speed the electric arc and d moves rapidly forming a loop inside the breaking chamber 5 and then out through the longitudinal central hole of the tube 8. When this cutoff gas passes through the plurality of annular spaces 18, it is vigorously cooled, which brings the the following advantages: the cutting gas thus produced more easily extinguishes the electric arc; the cutoff gas produced evacuates more easily and more quickly through the central hole of the tube 8; and the very rapid drop in the temperature of the cutoff gas prevents the appearance

  of the known phenomenon (described above) of the production of post-settling currents.

  It is thus possible to manufacture high voltage rotating arc switches that can operate with breaking powers in the range 40 to 50 kA while the dimensions of these circuit breakers are not greater or are even smaller than the dimensions of conventional similar switches having not the

  improvements according to the present invention.

  Figure 2 shows an alternative embodiment of the gas cooling device 14 according to the present invention. In this variant, the rings are thicker, are in smaller number, for example three, but are made of a gas-permeable metallic material, for example a porous metallic material or

  a metallic material consisting of agglomerated beads or sintered particles.

  As a result, the contact area between the gas and the metallic material is significantly increased, which increases the heat exchange between the gas and the rings.

  to cool the gas more efficiently.

  FIG. 3 represents another variant of the gas cooling device 14. In this other variant, there is provided around all the rings 15 a cylindrical annular piece 20 which is spaced apart from the outer edges 16 of the rings 15 and

  which is made of a porous metallic material.

  Figure 4 shows yet another alternative embodiment of the gas cooling device 14 according to the present invention. In this alternative embodiment, the rings 15 have a general flat plate shape, as before, but also comprise similar corrugations for each ring which have the consequence that, when the rings are stacked, the annular space 18 situated between each ring adjacent is a space that is a non-rectilinear path but a zigzag path because this space constitutes baffles. This causes a certain turbulence in the gas passing through the annular spaces 18, which further increases the heat exchange between the gas and the rings 15 in order to cool in a still

more efficient the gas.

  In the variant of FIG. 5, the stack of metal plates or rings of the gas cooling device 14 is fixed directly to the front part 30 of the coil 7 by means of bolts 32 (one of which is visible on the Figure 5). The coil 7 is formed by a succession of turns 34 connected in series, and assembled against each other by means of screws 36, which extend parallel to the bolts 32. The upper coil 34 of the coil 7 is in contact with a current supply range 37 connected to the upper terminal 38 of the circuit breaker. In the example of FIG. 5, the sheets 15 of the gas cooling device are electrically insulated from the coil 7 by means of isolation means comprising in particular an insulating bushing 40 through which each bolt 32 passes. According to a variant devoid of means isolation,

  the plates 15 of the cooling device are at the potential of the coil.

  The invention is not limited to the embodiments that have just been described by way of nonlimiting example. For example, it can be provided that the rings 15 are made of a metallic material but also of an insulating material. In the case where the rings 15 are made of an electrically conductive material, slits 30 (see FIG. 1A) can be provided in these rings in order to avoid or limit the appearance of eddy currents that can be induced in the rings. 15 by the

  presence of the coil 7 of the device for rotating the arc 6.

Claims (10)

  1. A rotary arc switch comprising: - a fixed contact (2), and a movable contact (3), - a sealed envelope (4) forming a breaking chamber (5) surrounding the fixed and movable contacts, - a device ( 6) to coil (7) to rotate the arc around said fixed contact, - and a cooling means (14) disposed in the interrupting chamber, characterized in that the cooling means (14) comprises a plurality of rings (15) planes or sheets arranged substantially parallel to each other and spaced from each other so as to constitute between them a succession of annular spaces (18) and that fastening means solidarize the cooling means (14) to a room Rigid switch. 2. rotating arc switch according to claim 1, characterized in that each of said rings (15) is in the general form of a substantially flat plate and thin disc-shaped having a central hole whose diameter is greater to the largest outer diameter of the movable contact (3) and in that the rings are arranged to surround the movable contact substantially centered   on the longitudinal central axis (9) of said switch.   Rotary arc switch according to claim 2, characterized in that the maximum spacing distance (C) between the fixed and moving contacts is equal to or less than the sum of the minimum distance (D1) between said cooling means and the fixed contact and the minimum distance (D2) between said cooling means and the   completely open mobile contact.   Rotary arc switch according to one of claims 1 to 3,   characterized in that said rings (15) are made in substantially flat metal sheets.   Rotary arc switch according to one of claims 1 to 3,   characterized in that said rings (15) are made in substantially flat insulating sheets.   Rotary arc switch according to one of claims 1   at 3, characterized in that said rings (15) are made in plates of a porous material.   Rotary arc switch according to one of claims 1 to 3,   characterized in that said rings (15) are made in substantially flat sheets having corrugations.   Rotary arc switch according to one of Claims 1 to 3, characterized   in that there is provided around said rings an outer cylindrical piece (20) located at   a certain distance from the outer edges (16) of the rings.   Rotary arc switch according to one of Claims 4, 6 or 7, characterized   in that said metal rings (15) comprise or less a radial slot (30).   Rotary arc switch according to one of Claims 1 to 9, characterized in that   the cooling means (14) is fixed to the front part (30) of the coil (7).