EP2593954B1 - A cutoff chamber device for two electrodes of confined contact - Google Patents

Description

The present invention relates to a switchgear apparatus for two confined contact electrodes, particularly in circuit breakers or switches of high voltage equipment.

Many devices include an insulator cover joining to each other the contact carriers in which the contact electrodes slide and which surrounds these electrodes. A main function of this insulator cover is to maintain a good coaxiality of the electrodes and thus facilitate the opening and closing maneuvers contacts. Their use is particularly common with electrodes arranged on a horizontal axis, which the forces of gravity can bend. Such apparatus is known from the document EP 0 836 209 A2 .

Particular difficulties however appear in the volume confined by the hood. The heating produced by the flow of current from one electrode to the other first limits the nominal current passing through the installation. The situation is even more difficult with the opening of the contact electrodes, since an electric arc appears briefly and produces a great heating, and a consequent overpressure, of the gas surrounding the arc, which can explode the hood.

A known measure is to have openings at the back of the electrodes to evacuate the gases at overpressure too high that the electric arc produced at the opening of the contacts. The hot gases are then found in the volume surrounding the electrodes and around the hood.

A primary object of the invention is to limit the heating of the electrodes during the ordinary service of the apparatus, the contacts being closed, despite the confinement of which the cover is responsible.

The invention relates to a switchgear apparatus comprising two contact electrodes movable between a closed position and an open position, two contact carriers supporting the electrodes and a cover joining the contact carriers and surrounding portions view of the electrodes, the cover comprising a dielectric main portion and two collars connecting ends of the main portion to the contact-holders, characterized in that the collars are provided with openings communicating a volume inside the cover and an external volume surrounding the interior volume.

The openings are formed through the collars, which can be made of conductive material easy to machine, allowing convection of the gas through the hood, and therefore a continuous renewal of the hot gas inside the hood by cooler external gas. It should be noted that the arrangement of the openings through the collars rather than the main portion of the cap confers marked advantages: the openings can be easily created in the collars, either by machining, the collars being often metallic, or from the manufacture of the collars , by molding or other method, if the collars are metal or polymeric or composite material, while maintaining sufficient mechanical strength through a greater freedom of design collars; while drilling the main portion of the hood, which seemed more appropriate since it is a thinner cylinder and overlooking the center of the confined volume, had actually resulted in greater disadvantages, since this main portion is the lowest of the hood , and that it is normally built in insulating fibers: its drilling would necessarily affect the mechanical strength of the hood as a whole, as well as its dielectric strength, the tips of the fibers cut by the machining may favor electricity flow paths .

Another difficulty arises with the situation mentioned above, evacuation of hot gases produced by the arc in the volume surrounding the hood: these gases may enter the volume confined by the hood through the openings and produce Arc reboots between the electrodes because of their high plasma content. It can however be avoided also in preferred embodiments of the invention, by sheltering the openings of the currents of these hot gases, which is easy if the openings are at the ends of the hood, in the collars, and would have been more difficult with openings in the center of the hood, at the junction of the electrodes where the surrounding volume must be cleared. According to a corresponding preferred arrangement, the collars are for this purpose provided with continuous partitions extending in radially protruding, which separate the openings of neighboring volumes where the hot gases are released and thus shelter the openings: the volume surrounding the hood is almost not invaded by hot gases, which therefore do not have the possibility of cross it.

The invention can be improved in several other aspects. If the collars each comprise a support ring on the contact carriers and an inner support portion of the main portion of the cover, the continuous partitions being joined to the support rings and the openings extending between the continuous partitions and the inner portions. , an anterior socket can be joined to the continuous partition, surrounding the inner portion, the openings then also extending between the inner portion and the anterior socket: the anterior socket contributes to better shelter the openings, while promoting the holding dielectric of the apparatus.

In a convenient construction, the inner portions are joined to the continuous partitions (by a separate means such as screws) and the openings extend between ribs established on the continuous partitions and on which the inner portions rest.

Anterior bushings may include a rounded bead protruding toward the main portion of the bonnet at a free end.

In a preferred arrangement, the contact carriers each comprise an outer edge defining a gas flow path from a recessed rear end of the electrodes, the curbs opening in front of the continuous walls, and the collars comprise a posterior socket joined to the continuous wall and surrounding one end of the outer curbs. This arrangement makes it possible to intercept the hot gases coming from the electrodes when the arc is formed by the continuous partitions, and to deflect them away from the hood and the junction zone of the electrodes.

The inner portions of the collars may further carry a field electrode, the field electrodes surrounding the contact electrodes and the openings also extending between the contact electrodes and the field electrodes.

According to a preferred arrangement, which can promote the quality of the convection of the flow, the openings extend to an angular portion of one of the collars and to an opposite angular portion to the previous one of the other collars.

• la figure 1 illustre une première réalisation de l'invention à l'état d'ouverture des contacts,
• la figure 2, une variante de cette réalisation,
• la figure 3, une vue en perspective d'un collier,
• et la figure 4, une vue de l'invention à l'état de fermeture des contacts.

The invention will now be described in detail with reference to the following figures:

• the figure 1 illustrates a first embodiment of the invention in the open state of the contacts,
• the figure 2 , a variant of this embodiment,
• the figure 3 , a perspective view of a necklace,
• and the figure 4 , a view of the invention in the closed state of the contacts.

We first consider figure 1 , as well as figure 4 . The interrupting chamber comprises a movable contact electrode (1) and a contact electrode (2) fixed coaxial with the preceding one. The electrodes (1 and 2) are supported by fixed contact carriers (3 and 4) which comprise in particular sleeves (5 and 6) in which the electrodes (1 and 2) are engaged and which are provided with elastic strips (7). and 8) electrically connecting the electrodes (1 and 2). They comprise passages (9 and 10) at posterior portions, which open into chambers internal to the sleeves (5 and 6), then, through other passages (11 and 12) through sleeves (5 and 6), annular chambers (13 and 14) extending between the sleeves (5 and 6) on the inside and cylindrical borders (15 and 16) on the outside, which further comprise connections (17 and 18) to the sleeves (5 and 6) at the rear but are open at the front, that is to say towards the electrode (2 or 1) opposite. The entire apparatus is arranged in a tank, not shown. The gaseous content is generally SF6 sulfur hexafluoride or other highly dielectric gas.

The electrodes (1 and 2) have outer contact portions (19 and 20), as well as internal contact portions (21 and 22) surrounded by the preceding ones, which remain in contact with each other longer than the previous ones at the opening. of the device and between which an arc (23) is caused to develop at the opening of the contacts. An arc-blowing nozzle (24) of dielectric material connects the electrodes (1 and 2) surrounds the inner contact portions (21 and 22) and confines the arc (23). The blowing of the arc (23) is provided by known means, for example by the expansion of the gas first contained in a chamber (25) compressed between a partition (26) of the sleeve (5) and the electrode ( 1) mobile, and which is projected in front of the electrode (1) towards the arc (23) by an opening (27) passing through the bottom of this electrode, as soon as the compression becomes sufficient to open a valve (28) equipping this opening (27).

The centering of the electrodes (1 and 2) is provided by a cover (29) comprising a main portion (30) of cylindrical shape and two collars (31 and 32) respectively fixed to the contact-holders (3 and 4). The main portion (30) is dielectric, the collars (31 and 32) may be of conductive material; they are almost identical. Each of them comprises a support ring (33 or 34) making the connection to the sleeves (5 or 6), a continuous partition (35 or 36) flat and extending around the support ring (33 or 34), protruding beyond the main portion (30) radially (perpendicular to the axis of the electrodes (1 or 2)), an anterior sleeve (37 or 38) cylindrical and extending from the outer edge of the partition continuous (35 or 36) to the other collar (32 or 31), and a posterior sleeve (39 or 40) also cylindrical and opposite to the previous one, extending from the outer edge of the continuous partition (35 or 36), and surrounding the end of the sleeve (15 or 16), which arrives not far from the partition (35 or 36). Ribs (41 or 42) - better visible at the figure 3 standing on the continuous partitions (35 or 36) on the side of the front bushes (37) serve to support an inner portion (43 or 44) of the collars (31 or 32). The ends of the main portion (30) of the cover (29) are crimped into these inner portions (43 and 44). The cover (29) is unitary, screws (59 or 60) joining the inner portions (43 or 44) to the continuous partitions (35 or 36). The inner portions (43 or 44) each further support a field electrode (45 or 46), which surrounds the anterior end of the outer portion (19 or 20) of one of the contact electrodes (1 or 2) without the to touch. The field electrodes (45 and 46) are directed towards each other.

The cover (29) is traversed by openings (47 or 48) which extend through each collar (31 or 32) and comprise first portions (49 or 50), between the continuous partition (35 or 36) and the inner portion (43 or 44), and between the ribs (41 or 42), a second portion (51 or 52) between the anterior sleeve (37 or 38) and the inner portion (43 or 44), and a third portion ( 53 or 54) at the end of the anterior bushing (37 or 38), at a beaded end, inwardly protruding (55 or 56) whose shape is rounded.

The operation of the invention is as follows. When the contacts are closed, the gas contained in the hood (29) heats up and a convection occurs through the openings (47 and 48): the lighter hot gas leaves the interior volume (57) confined by the hood (29) through the upper openings, and gas from the outer volume (58) surrounding the hood (29) replaces it by the lower openings. A satisfactory ventilation of the electrodes (1 and 2) is thus obtained.

When the contacts are open and an arc (23) appears, the hot gases it produces are first discharged into the annular chambers (13 and 14) and then blown to the collars (31 and 32), but the partitions continuous (35 and 36) stop them, and the rear sockets (39 and 40) make them turn around and away from the outer volume (58), preventing them from reaching the openings (47 and 48).

In a particular embodiment shown in figure 2 , the openings (47) of one of the collars (31) are located at the top, and the openings (48) of the other collars (32) are located at the bottom, or more generally the openings of the collars are placed only at opposing angular sectors on the circumferences of the collars (31 and 32), which imposes a diagonal path to the ventilation gas passing through the middle of the interior volume (57), and ensures good ventilation. This variant can be realized by adding plugs (61 and 62) filling the sections of the other openings between the ribs (41 and 42).

The figure 2 represents the convection movement by the arrows (63), as well as the hot gas evacuation movements associated with the cutting of the electric arc by the arrows (64 and 65). The realization of the figure 1 still has convective movements symmetrical to those of the arrows (63).

The collars (31 and 32) can be manufactured at low cost by molding aluminum. The openings (47, 48) are sized large enough to allow the desired convection flow rate. The sinuous shape of the openings is not particularly sought after but arises from the existence of the anterior bushings (37, 38) and the field electrodes (45, 46) in the illustrated embodiments; rectilinear openings could be chosen in the absence of these elements.

Claims (9)

1. Arc-control chamber gear comprising two contact electrodes (1, 2) movable between a closed position and an open position, two contact carriers (3, 4) supporting the electrodes, and a cap (29) joining the contact carriers together and surrounding the facing portions of the electrodes, the cap comprising a main dielectric portion and two collars (31, 32) connecting the ends of the main portion to the contact carriers (3, 4), the gear being characterized in that the collars are provided with openings (47, 48) causing an inside volume (57) inside the cap in which said facing portions of the electrodes extend to communicate with an outside volume (58) outside the cap and surrounding the inside volume.
2. Gear according to claim 1, characterized in that the collars (31, 32) comprise a continuous partition (35, 36) projecting beyond the main portion in a radially outward direction, and the openings extend through the collars between the main portion (30) and the continuous partitions (35, 36).
3. Gear according to claim 2, characterized in that the collars comprise a support ring (33, 34) on the corresponding contact carrier (3, 4) and an inner portion (43, 44) for supporting the main portion, the continuous partitions (35, 36) are joined to the support rings, and the openings extend between the continuous partitions and the inner portions.
4. Gear according to claim 3, characterized in that the inner portions (43, 44) are assembled to the continuous partitions (35, 36) and the openings extend between tabs (41, 42) established on the continuous partitions and against which the inner portions bear.
5. Gear according to claim 3 or claim 4, characterized in that the collars comprise a front bushing (37, 38) joined to the continuous partition and surrounding the inner portion, the openings also extending between the inner portion and the front bushing.
6. Gear according to claim 5, characterized in that the front bushings (37, 38) include, at a front end, a rounded bead (55, 56) projecting towards the main portion (30).
7. Gear according to any one of claims 2 to 6, characterized in that the contact carriers (3, 4) have an outer edging (15, 16) defining a path for gas flow from an open rear end of the electrodes, the edgings opening facing the continuous partitions, and the collars (39, 40) have a rear bushing joined to the continuous partition and surrounding one end of the corresponding outer edging.
8. Gear according to claim 3, characterized in that the inner portions of the collars carry a field electrode (45, 46), the field electrodes surrounding the contact electrodes (1, 2) and the openings also extending between the contact electrodes and the field electrodes.
9. Gear according to any one of claims 1 to 8, characterized in that the openings extend over an angular portion (31) of one of the collars and over an opposite angular portion of the other collar (32) in such a manner as to impose a diagonal path on the flow of ventilation gas by convection, said path passing through the middle of the inside volume (57).

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