EP2237301B1 - Interruptor chamber with mobile contact and independently movable blowing nozzle, by pass interruptor and substation with HVDC converter comprising such chamber - Google Patents

Description

TECHNICAL AREA

The invention relates to a current breaking chamber.

It relates more particularly to the power failure in HVDC (High Voltage Direct Current in English).

It relates to the kinematics of contact (s) movable (s) and nozzle gas blowing in a room of power failure.

It finds particular application in the realization of HVDC bypass switch and in its integration in an HVDC conversion substation.

PRIOR ART

The DE 829 916 describes all the features of the preamble of claim 1. An HVDC conversion substation aims to convert a high voltage direct current, typically greater than 200 kVDC, into an alternating current also under high voltage.

• couper un courant dit courant de charge inductive provenant des transformateurs convertisseurs jusqu'à une valeur de l'ordre de 1000A pour commuter le courant qui passe dans les thyristors 6, 7, 8 ou 9,
• supporter une valeur nominale de haute tension élevée, typiquement 400 kVCC, pendant toute la durée de vie du système et à des températures extrêmes pouvant descendre à -50°C,
• se fermer très rapidement, typiquement en un temps de l'ordre de plusieurs dizaines de ms,
• supporter des pointes de courant de plusieurs dizaines de kA: dans les conditions les plus défavorables, ces pointes de courant peuvent se produire lors de la phase de coupure d'arc,
• s'ouvrir et de se refermer immédiatement à la suite d'une ouverture dans le cas où l'arc n'a pas été réellement coupé,
• supporter l'arc durant tout sa durée sans dégât.

An HVDC transmission system architecture using several HVDC substations is for example described in the patent WO 2007/084041 . The described system comprises two substations 2, 3 separated from each other by a high voltage line 10 and a grounding return line 11. Each substation 2 or 3 comprises several HVDC bypass switches 12, 13 or 14, 15. The primary function of each bypass switch HVDC is to constitute a by-pass of each converter transformer to which it is folded. Also, each HVDC bypass switch must be suitable for:

• to cut a current, referred to as an inductive load current, from the converter transformers to a value of the order of 1000 A to switch the current flowing through the thyristors 6, 7, 8 or 9,
• withstand a high rated high voltage rating, typically 400 kVDC, throughout the life of the system and at extreme temperatures down to -50 ° C,
• close very quickly, typically in a time of the order of several tens of ms,
• withstand current peaks of several tens of kA: under the most unfavorable conditions, these current peaks can occur during the phase of arc failure,
• open and close immediately following an opening in the event that the bow has not actually been cut,
• to support the bow during all its duration without damage.

1. 1- utiliser plusieurs chambres de coupure reliées entre elles en série électrique,
2. 2- augmenter le dégagement de l'espace isolant d'une chambre de coupure donnée,
3. 3- réaliser une buse de soufflage dans un matériau isolant qui supporte les contraintes diélectriques élevées.

We can distinguish in three categories the elements of technical solution retained until today to achieve this type of HVDC bypass switch:

1. 1- use several interrupter chambers interconnected in electrical series,
2. 2- increase the clearance of the insulating space of a given breaking chamber,
3. 3- make a blow nozzle in an insulating material that withstands high dielectric stresses.

1. 1- l'utilisation de plusieurs chambres de coupure augmente nécessairement le coût de réalisation et l'encombrement en pied des interrupteurs dans une sous-station HVDC, nécessite de mettre en oeuvre des moyens électriques et/ou électroniques supplémentaires pour synchroniser le déclenchement de la manoeuvre des contacts mobiles entre chambres et nécessite enfin dé mettre en oeuvre des appareils de répartition de tension pour distribuer la tension entre les interrupteurs by-pass HVDC.
2. 2- l'espace isolant, avec un dégagement augmenté nécessite de prévoir des vitesses de manoeuvre augmentées car, l'interrupteur HVDC a des contraintes de durée de fermeture très rapide. Cela nécessite le choix d'une commande mécanique plus puissante et grève ainsi le coût de l'interrupteur HVDC.
3. 3- nombre de matériaux, tels que le PTFE ont été éprouvés en tant que constituant des buses de soufflage pour la haute tension en courant alternatif. Ces buses ont fait leurs preuves de leur efficacité comme étant capables de supporter les contraintes diélectriques alternatives élevées. La demanderesse a de forts doutes quant à la tenue diélectrique à long terme en courant continu pour les matériaux constituant les buses de soufflage actuellement connus. Par ailleurs, il est connu que le champ électrique qui peut être supporté est toujours plus élevé à l'interface entre le gaz isolant, tel que le SF6, et les parties métalliques conductrices qu'à l'interface entre le gaz isolant et le matériau isolant de la buse. Ainsi, jusqu'à présent, par construction des chambres de coupure connues, le champ électrique doit être réduit dans les zones dans lesquelles la buse isolante est solidaire d'un des contacts métalliques. Cela canduit à augmenter nécessairement les dimensions radiales de la chambre de coupure et donc son coût. De plus, les gradients admissibles dans le gaz isolant tel que le SF6 sont supérieurs aux valeurs admissibles dans un isolant solide. Ceci contraint nécessairement à augmenter aussi les dimensions axiales de la chambre de coupure lorsque des isolants solides sont présents dans la zone de coupure.

The major disadvantages of these technical solution categories can be listed as follows:

1. The use of several breaking chambers necessarily increases the cost of production and footprint of the switches in an HVDC substation, requires the use of additional electrical and / or electronic means to synchronize the triggering of the Maneuver moving contacts between rooms and finally requires to implement voltage distribution devices to distribute the voltage between bypass switches HVDC.
2. 2- the insulating space, with increased clearance requires to provide increased maneuvering speeds because the HVDC switch has very fast closing time constraints. This requires the choice of a more powerful mechanical control and thus strike the cost of the HVDC switch.
3. 3- number of materials, such as PTFE have been tested as constituting blowing nozzles for AC high voltage. These nozzles have been proven to be effective in being able to withstand high alternative dielectric stresses. The Applicant has strong doubts as to the long dielectric strength DC term for the materials constituting the currently known blowing nozzles. Furthermore, it is known that the electric field that can be supported is always higher at the interface between the insulating gas, such as SF6, and the conductive metal parts at the interface between the insulating gas and the material. insulation of the nozzle. Thus, until now, by construction of the known breaking chambers, the electric field must be reduced in the areas in which the insulating nozzle is secured to one of the metal contacts. This candles to necessarily increase the radial dimensions of the breaking chamber and therefore its cost. In addition, the allowable gradients in the insulating gas such as SF6 are higher than the allowable values in a solid insulator. This necessarily forces to increase also the axial dimensions of the interrupting chamber when solid insulators are present in the cutoff zone.

The object of the invention is then to overcome the aforementioned drawbacks and to propose a solution that makes it possible to obtain an HVDC bypass switch with reduced space and cost.

STATEMENT OF THE INVENTION

• une seule paire de contacts dont au moins un est mobile en translation selon l'axe longitudinal par l'action d'une tige de manoeuvre,
• une paire de capots pare effluve agencés avec leurs embouts respectifs séparés l'un de l'autre d'une distance e donnée fixe selon l'axe longitudinal en définissant un espace isolant et agencés individuellement autour de chacun des contacts de la seule paire quelle que soit leur position,
• une buse isolante de soufflage de gaz, de forme générale tubulaire, également mobile en translation selon l'axe longitudinal,

dans laquelle le(s) contact (s) mobile(s) et la buse tubulaire étant mobiles indépendamment l'un de l'autre de sorte que :

• dans la position de fermeture des contacts, la buse tubulaire est dans une position dite de confinement selon laquelle elle s'étend au moins dans l'espace isolant de longueur e en entourant les contacts,
• pendant une manoeuvre d'ouverture, la buse tubulaire reste maintenue sensiblement dans sa position de confinement au moins jusqu'à ce que le(s) contact(s) mobile(s) ai(en)t atteint(s) la position d'ouverture,
• une fois la manoeuvre d'ouverture réalisée et tout courant coupé, la buse tubulaire est déplacée dans une position dite de retrait dans laquelle elle est retirée de l'espace isolante.

To achieve this object, the invention provides a current-breaking chamber extending along a longitudinal axis and comprising:

• a single pair of contacts of which at least one is movable in translation along the longitudinal axis by the action of an operating rod,
• a pair of corona shields arranged with their respective ends separated from each other by a given distance e fixed along the longitudinal axis by defining an insulating space and arranged individually around each of the contacts of the only pair whatever their position,
• an insulating nozzle for gas blowing, of tubular general shape, also movable in translation along the longitudinal axis,

wherein the movable contact (s) and the tubular nozzle are movable independently of one another so that:

• in the closed position of the contacts, the tubular nozzle is in a so-called confinement position in which it extends at least in the insulating space of length e by surrounding the contacts,
• during an opening maneuver, the tubular nozzle remains substantially in its confinement position at least until the movable contact (s) have reached the position of opening,
• once the opening maneuver is performed and any current cut, the tubular nozzle is moved to a so-called withdrawal position in which it is removed from the insulating space.

The inventors have not only succeeded in decoupling the HVDC voltage withstand and the DC cut-off, but, moreover, they have managed to achieve these performances by using a single breaking chamber thanks to the separation mechanics of the contacts and the insulating blowing nozzle in the same chamber.

Thus, even if there are still risks of electrical rebooting and therefore of maintaining the direct current during a maneuver, opening of the contacts, the tubular nozzle according to the invention is held in position substantially in its confinement position, which makes it possible to confine the arc in the zone, the insulating gas polluted by any arc and to evacuate it easily outside the electrical contact zone.

The removal of the insulating tubular nozzle in a dielectrically unconstrained zone is according to the invention carried out only after cutting off any current.

In other words, in HVDC, a bypass switch comprising a single breaking chamber according to the invention performs the functions of confining all the current arcs likely to occur and to maintain the voltage recovery voltage (Voltage Recovery Volage) .

According to the invention, the nozzle is maintained, during an opening maneuver, in its position of confinement by pneumatic thrust of the insulating gas from the chamber on the nozzle.

According to this mode, the pneumatic thrust is advantageously performed on a part integral with the nozzle and shaped as a piston, said piston being slidably mounted around one of the movable contacts in a fixed part constituting the contact holder.

Advantageously, the displacement of the nozzle towards its retracted position of the insulating space is realized after a period of time determined with respect to the time of complete opening of the contacts made.

This period of time is preferably determined so as to be able to perform a closing maneuver of (es) movable contact (s) when the nozzle is maintained in its confinement position and that there always remains a current to be cut. According to a preferred variant, the lapse of time is of the order of 100 ms. This time is chosen so that a suitable electronics can verify that any current has been interrupted. Thus, if there is still a current, the closure of the contacts is still possible while the tubular blowing nozzle has remained substantially in its initial confinement position.

According to a preferred variant, the displacement of the nozzle towards its position of withdrawal of the insulating space is achieved by a compression spring whose one end is fixed and the other is connected to a part itself integral with the movable nozzle, the expansion of the spring to the position of withdrawal of the nozzle being performed after the determined lapse. Thus, the withdrawal of the nozzle to its withdrawn position can be achieved solely by the energy stored by the spring in the compressed state.

The compression spring is advantageously arranged in a variable volume V1 defined between the piston and the contact holder. Also preferably, one of its ends bearing against the contact door while its other end is secured to the piston.

• lors d'une manoeuvre de fermeture, évacué sous l'action du piston en butée mécanique contre l'épaulement du contact mobile par le canal et le clapet anti-retour en position dégagée du canal, de sorte à réduire le volume V1 au minimum pour loger le ressort à l'état comprimé,
• lors d'une manoeuvre d'ouverture, maintenu au minimum pendant le laps de temps déterminé aux fuites pneumatiques près présentes entre d'une part le piston et le porte contact et d'autre part le clapet anti-retour et le porte contact, sous l'action de la différence de pression régnant entre le volume V1 et un volume V2 défini entre le porte contact et le contact mobile du côté du piston opposé à celui où est agencé le ressort, ladite différence de pression compensant l'effort de poussée du ressort comprimé contre le piston pendant le laps de temps déterminé.

One of the movable contacts preferably comprises a shoulder and the contact holder comprises at the volume V1 a channel opening on which is mounted a non-return valve. The insulating gas present in the volume V1 is thus:

• during a closing maneuver, evacuated under the action of the piston in mechanical stop against the shoulder of the movable contact by the channel and the non-return valve in the open position of the channel, so as to reduce the volume V1 to the minimum for place the spring in the compressed state,
• during an opening maneuver, kept to a minimum during the determined lapse of time to the pneumatic leaks present between the piston and the contact holder on the one hand and the non-return valve and the contact holder on the other hand, under the action of the pressure difference between the volume V1 and a volume V2 defined between the contact holder and the moving contact on the side of the piston opposite that in which the spring is arranged, said pressure difference compensating the thrust force of the spring pressed against the piston during the determined period of time.

By "pneumatic leakage" is understood here and in the context of the invention, the leakage of the insulating gas between the parts of the interrupting chamber concerned.

• la partie tubulaire du piston reliant sa tête à la buse est agencée à distance du contact mobile et comprend un trou débouchant,
• la portion de tête du piston entre le contact mobile et le tube du piston comprend un autre trou débouchant entre les volumes V1 et V2, le trou débouchant de le tube de piston étant agencé de sorte qu'après le laps de temps déterminé, les fuites pneumatiques aient amené le piston dans une position permettant au gaz du volume V2 de pénétrer dans le volume V1 par les trous débouchant, ce qui accélère le déplacement de la buse solidaire du piston, vers sa position de retrait.

According to an advantageous construction:

• the tubular portion of the piston connecting its head to the nozzle is arranged at a distance from the movable contact and comprises a through hole,
• the head portion of the piston between the movable contact and the piston tube comprises another hole opening between the volumes V1 and V2, the hole opening out of the piston tube being arranged so that, after the determined period of time, the leaks pneumatic have brought the piston in a position allowing the gas volume V2 to enter the volume V1 through the through holes, which accelerates the movement of the nozzle integral with the piston to its retracted position.

It is quite possible according to the invention to provide that the two contacts are movable, transmission means between contacts for mutually separating the contacts being provided in the chamber. We thus have a break chamber called "double movement".

The invention also relates to a high-voltage switch comprising a breaking chamber as mentioned above.

The switch may be a circuit breaker or bar disconnect or earthing switch.

It may advantageously be a bypass switch HVDC, comprising in a preferred embodiment a single breaking chamber.

Such a HVDC bypass switch with a single interrupting chamber can cut a current of up to 100A or even 1000A with a voltage to be held by said chamber can reach at least 400kV DC.

The invention finally relates to an HVDC conversion substation comprising at least one HVDC bypass switch as described above.

According to a particularly advantageous arrangement, the axis of the interrupter chamber of the switch is substantially vertical. Such an arrangement is advantageous, in particular because it makes it possible to collect the polluted particles resulting from the cuts solely by gravity at the bottom of the chamber (s) and that it allows a simpler assembly of the nonreturn valves used. according to the invention for the evacuation of gas by the piston.

BRIEF DESCRIPTION OF THE DRAWINGS

• la figure 1 représente en fonction du temps une des allures possibles de tension CC susceptible d'être présente dans un interrupteur by-pass HVDC selon l'invention, une fois la commutation réalisée (ouverture des contacts),
• les figures 2A à 2C représentent les différentes positions prises par les moyens d'une chambre de coupure de courant selon l'invention, à savoir respectivement la position de fermeture des contacts, la position d'ouverture des contacts avec la buse de soufflage en position de confinement et enfin la position d'ouverture des contacts avec la buse de soufflage en position de retrait,
• la figure 3 montre les courbes représentatives en fonction du temps des courses de translation respectivement du contact mobile et de la buse de soufflage de la chambre de coupure selon les figures 2A à 2C.

Other advantages and characteristics of the invention will emerge more clearly on reading the detailed description given by way of illustration and in no way limiting with reference to the figures among which:

• the figure 1 represents, as a function of time, one of the possible DC voltage steps likely to be present in an HVDC bypass switch according to the invention, once the switching has been performed (opening of the contacts),
• the FIGS. 2A to 2C represent the different positions taken by the means of a current-breaking chamber according to the invention, namely respectively the closing position of the contacts, the opening position of the contacts with the blowing nozzle in the confinement position and finally the opening position of the contacts with the blowing nozzle in the retracted position,
• the figure 3 shows the representative curves as a function of time of the translation strokes respectively of the movable contact and the blow nozzle of the breaking chamber according to the FIGS. 2A to 2C .

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

The interruption position of a single interrupting chamber of an HVDC bypass switch according to the invention is shown in FIGS. Figures 2B and 2C . On average, for a HVDC bypass switch whose voltage to hold can reach at least 400kV DC DC current, the current to be cut is relatively low since up to 100A or even 1000A.

On the figure 1 , is shown the representative curve of the voltage of an HVDC system likely to be present at the terminals of an HVDC bypass switch according to the invention once the interruption of the current carried out. The current flowing through the switch has a similar periodicity. We see a high oscillation frequency of the order of 12 times the frequency of an AC network with which an HVDC conversion substation comprising a bypass switch HVDC is connected.

Consequently, unlike the alternating current that it is possible to cut naturally at zero current, the difficulty of power failure Continuous comes from the fact that a zero current appears several times during a switch, typically every 0.8 ms. Also, when switching, several arcing reboots are possible.

For unstable current arcs less than about 1000A and more frequently, during re-ignitions that may occur during the breaking of inductive currents, it is possible that the arc foot leaves the arc contact to hang on to the discharge barrier.

Therefore, the inventors propose a new kinematic of a cutoff chamber for the removal of the blast nozzle from the insulating space between fumes in a dielectrically unconstrained area only when any arc has been cut. In other words, the blowing nozzle must remain substantially in place in its confinement position for the duration of an opening maneuver, which makes it possible to ensure that any arc has been cut.

The breaking chamber 1 according to the invention shown in FIGS. FIGS. 2A to 2C extends along a longitudinal axis XX 'and is filled with an insulating gas, such as SF6, nitrogen, CF4 or CO2 or a SF6 + nitrogen mixture ... The chamber 1 comprises all firstly a single pair of contacts 2, 3.

One of the contacts 2 is fixed and has a solid rod shape.

The other of the contacts 3 is movable along the axis XX 'and has a tulip shape. More exactly, the movable contact 3 comprises a tube internally hollow 30 coupled directly to an actuating rod in translation at a fastener 300. At the free end, the tube 30 is connected to the actual contact part 31 in the form of a tulip of inner shapes complementary to those 2. The hollow tube 30 also has a narrowing of external shapes by defining a shoulder 301. On its widened part, a flange 302 forming a piston (as explained later) is fixed in s' extending radially to the axis XX '. The hollow tube is pierced with one or more openings 303 opening at the rear of this flange 302 (that is to say, the side closest to the fastener 300 with the operating rod).

The hollow tube 30 finally comprises a narrowing 304 of internal diameter or in other words a narrowing of the gas passage section as detailed by the .suite.

This interrupting chamber 1 further comprises a pair of corona shields 40, 41 whose primary function is to cancel at least reduce the peak effect at the contacts (or the tip of the contacts): level, the electric field tends to tend to infinity, which can contribute to the ionization of the gas and thus the initiation of a possible electric arc. The respective endpieces 400, 410 of each cap delimiting circular openings and are spaced a fixed distance e.

The fixed bow rod 2 is arranged in the circular opening of the endpiece 400, while the movable contact in the form of a tulip 3, 30 and 31 is arranged in the circular opening of the other endpiece 410 regardless of its position ( Figures 2A to 2c ).

The interrupting chamber also comprises an arc-blowing nozzle 5 of insulating material of tubular general shape and movable in translation along the longitudinal axis XX '. The inner diameter 0 of the nozzle 5 is preferably adjusted to the outer diameter of the hollow tube 30 of the movable contact 3. The radial height, ie the outside diameter of the tubular nozzle 5 is advantageously chosen in a minimal manner to achieve effective dielectric confinement and ensuring optimum dielectric coordination between corona shields 40, 41 and electrical contacts 2, 3.

The nozzle 5 is integral with a piston member 6 which is slidably mounted around the movable contact 3, 30 away from the latter and in a fixed part 7 constituting the contact holder.

More exactly, the piston 6 comprises a tubular portion 60 hollow internally with several different diameters in continuity with one another. An end 600 of this piston tube 60 has an inside diameter for the inner fixing of the nozzle 5 and a guide of the hollow tube 30 of the movable contact 3 when sliding inside. The other end 601 of the piston tube 60 has a diameter greater than that of the hollow tube 30 of the moving contact by delimiting a space whose function will be described later. This end 601 is integral with the head portion 61 of the piston 6 and is pierced with at least one through hole 6010.

The head 61 of the piston 6 has an internal diameter for guiding the hollow tube 30 of the movable contact 3 and is pierced with another opening hole 6100. Thus, the two holes opening 6010 and 6100 can communicate with each other by the volume defined by the remote arrangement of the hollow tube 30 with the end 601 of the tube of diameter greater than the end 600 supporting the tubular nozzle 5.

The head 61 of the piston 6 is moreover shaped to make a mechanical stop with the shoulder 301 of the tube 3.

The contact holder 7 is of homothetic internal shapes with those outside the piston 6 to allow their relative sliding with interlocking. Seals 67 are provided between the piston and the contact holder 7. Between the piston 6 and the contact holder 7 is defined a variable volume V1 of insulating gas which accommodates a compression spring 8 constituted by a coil spring whose turns are wound around the tube portion 60, 600, 601 as explained later. The function of this compression spring 8 is the return of the piston 6 and thus of the nozzle 5 secured to the latter between its confinement position ( Figures 2A and 2B ) to its withdrawal position ( Figure 2C ), when no mechanical force by mechanical stop between said piston 6 and the shoulder 301 of the hollow tube 30 or a pneumatic force of the insulating gas prevailing in the chamber oppose it. The helical spring 8 advantageously has in the illustrated embodiment an end in permanent support against the bottom 70 of liner 7 and the other end also in permanent support against the head 61 of the piston 6 regardless of the relative position of the latter in the contact door ( FIGS. 2A to 2C ).

The hollow tube 30 of the movable contact 3 is mounted in the contact holder 7 so that the piston flange 302 is guided as tightly as possible inside said sleeve 7. Even if this is not shown, this flange piston 302 houses at its periphery an electrical contact in the form of a metal braid or sliding type. This contact ensures the passage of electric current from the terminal to which the switch is connected by the liner 7 and to the movable contact 3 in the form of a tulip. Advantageously, an electrical contact is chosen which is flexible because it does not have to provide mechanical guiding of the tube 30.

Thus, at the rear of the piston head 61, that is to say between the piston head 61 and the piston flange 302 is defined a variable volume V2 of insulating gas.

At the rear of the piston flange 302 of the hollow tube 30 is fixed inside the contact holder 7. a ring 9 which also guides in the most tight manner possible the hollow tube 30. Thus, between the piston flange 302 of the hollow tube 30, the ring 9 fixed in the contact holder 7 and the narrowing of the gas passage section 304 by the inside of the tube hollow 30 is defined a variable volume V3 of insulating gas.

In the embodiment illustrated in FIGS. 2A to 2C , the mechanical guide points of the contact tube 30 are made by the inner diameter of the joke 9 and the piston head 61. The piston tube 60 is mechanically guided by the segments 67 also ensuring the sealing function

On the ring 9 are mounted two valves 91, 92. Each valve consists of a plate bearing against the ring 9 at a channel opening. One of the valves 91 has the function, when it is open, of allowing the volume V3 to be filled by the insulating gas coming from the rear of the ring 9, that is to say on the fastener side 300. The other function of the valves 92 is, when open to allow the unloading of a portion of the gas present in the volume V3 as explained later. The setting springs of the pads 91, 92 against the ring 9 are not shown in FIG. Figures 2A, 2B , 2C . Only the pin or pin 910 for deflection of the filling valve 91 is represented in FIG. FIGS. 2A to 2C .

The horn cover 41 arranged around the movable contact 3 regardless of its position is fixed to the contact holder 7 by defining, to the pneumatic leakage of insulating gas near between the piston 6 or the tubular nozzle 5 and the nozzle 410, a volume of substantially fixed insulating gas V4.

The contact carrier 7 is pierced with a channel 71 opening on the one hand on the variable volume V1 in which is housed the piston 6 and secondly on the volume V4 delimited by the corona cover 41 and the contact holder 7 to which it is attached. On this outlet channel 71 is mounted a non-return valve 10 so as to evacuate the insulating gas present in the volume V1 to the volume V4 as explained below. In the illustrated embodiment, the non-return valve 10 consists of a plate bearing against the contact holder 7 at the opening channel 71 via a set of three identical pins 11 and arranged at 120 ° from each other when no gas from V1 exerts pressure. The support of the plate 10 against the contact holder 7 is made by weakly calibrated springs surrounded individually around each rod.

The operation of the breaking chamber 1 according to the invention will now be explained with reference to FIGS. 2A to 2C and an opening maneuver and a closing maneuver.

In the closed position of the contacts 2,3 ( Figure 2A ), the shoulder 301 maintains in position the piston 6 and thus the spring 8 in the compressed state whose thrust is then compensated. In this closed position, the nonreturn valve 10 is closed, the hole 6010 does not open on the volume V1. As illustrated in Figure 2A , the hole 6010 is opposite the door contact 7: it can just as well be beyond the contact door 7 and lead into the volume V4 frozen.

When an opening maneuver of the HVDC bypass switch comprising the breaking chamber 1 according to the invention is triggered, the tube hollow 30 of the movable contact 3 is pulled at its attachment 300 with the operating rod, to the right in the figures.

The piston flange 302 then reduces the volume V3 and there is shown a pressure of the gas volume which extends from the ring 9 to the internal narrowing 304 of the hollow tube 30 of the movable contacts 3, that is to say ie, corresponding substantially to the initial volume V3 (from the space between the piston flange 302 and the ring 9 fixed in the contact holder 7 to the inner volume of the hollow tube 30, that is to say until the shrinkage of gas passage section 304 through the inside of the tube 30). The arrows referenced GI in Figure 2B indicate the passage of the insulating gas which rises in pressure from the volume V3 which is reduced to the narrowing 304 of passage section in the hollow tube 30.

The choice of the location of the passage section narrowing 304 and the pressure in the volume V3 are judiciously chosen. Indeed, the inventors started from the observation that a decrease in the density of the insulating gas was harmful insofar as the dielectric strength decreases with the density of gas. However, during an opening maneuver the blowing volume to the smallest gas passage section increases in pressure. However, at the outlet of this volume, if the overpressure exceeds a critical value there may be a drop in gas density, that is to say from the smallest section of gas passage. If this decrease is too important and it occurs at the level of the actual contact part 31 (tulip), the dielectric withstand of the latter at the transient recovery voltage (TTR) immediately after the interruption of the current may not be ensured. Indeed, the electrical gradients after cutting that take place in this portion tulip 31 are particularly high.

Thus, the inventors have judiciously defined a section narrowing 304 upstream of the tulip portion 31. This narrowing 304 is of flow section smaller than that of the tulip and may be an integral part of the hollow tube 304 or be constituted by a piece reported for example by screwing at the end of hollow tube.

In addition, the critical pressure not to be exceeded according to the invention is that to which, despite the implantation of the narrowing 304 upstream of the tulip 31, a low gas density zone could be established between the narrowing 304 and the immediately in the vicinity of the end of the tulip 31. In the embodiment illustrated, the relief valve 92 is thus adjusted so that it opens to its maximum at the critical pressure and therefore, under these conditions , the low density value of the gas is limited in the dielectrically stressed zone.

The load shedding valve 92 has in the application according to the invention, namely the interruption in bypass HVDC, an additional function. Indeed, during a maneuver opening of a bypass switch HVDC provided with a chamber according to the invention and in the event of a switching fault, the power thyristors equipping the HVDC current conversion substation, a current arc of the order of a few tens of kA may appear between the arcing contacts 2, 3. A rise in pressure can then occur in the space e and by therefore, in the volume V3 in a direction opposite to the direction of blow (that is to say from left to right on the FIGS. 2A to 2C ). The extreme risk of this rise in pressure is therefore an unexpected closure of the contacts 2,3. To avoid this reclosing, the relief valve 92 must be calibrated to be opened early enough during the opening maneuver and therefore open at a relatively low pressure.

• il ne s'ouvre pas, lors de manoeuvres d'ouverture à la pression de remplissage du gaz isolant de l'interrupteur muni de la chambre de coupure, interrompant son courant,
• il s'ouvre à son maximum, lors de manoeuvres d'ouverture pour tentative de coupure de courant, mais en présence d'un défaut de commutation des thyristors.

In fact, the inventors have chosen to adjust the setting of the unloading valve 92 so that:

• it does not open, during opening maneuvers at the filling pressure of the insulating gas of the switch provided with the interrupting chamber, interrupting its current,
• it opens at its maximum, during opening maneuvers for attempted power failure, but in the presence of a switching fault thyristors.

During an opening maneuver ( FIGS. 2A to 2C ), the shoulder 301 no longer mechanically compensates for the thrust of the compressed spring 8.

The pneumatic leaks present between the piston 6 and the contact holder 7 on the one hand and the nonreturn valve 10 and the contact holder 7 on the other hand can then act and recess in a position slightly offset from its original position of the Figure 2A . The pressure prevailing in the volume V2 compensates for the thrust force of the compressed spring 8 against the piston 6, 61 for a determined lapse of time ΔT beyond the time T1 set to reach the open position of the contacts 2, 3. Otherwise said, during an overall time ΔT + T1 while the movable contact 3, 30 undergoes a translation travel and passes from its closed position F ( Figure 2A ) at its open position O ( Figure 2B ), the tubular blowing nozzle 5 remains substantially in its confinement position (position C on the Figure 2A and C0 position on the Figure 2B ). In fact, the removal of the nozzle stops initially when the pressure difference between the volume V2 and the volume V1 compensates for the thrust of the spring 8.

In other words, regardless of the operation performed (opening or closing), the pressure in the volume V2 remains unchanged and substantially equal to the insulating gas filling pressure of the entire switch including the interrupting chamber. For this purpose, one or more opening holes, not shown, are formed in the contact holder 7, which allows a balancing of the pressures between the volume V2 and the rest of the filling volume of the high voltage apparatus provided with the chamber cut. Also, during a closing maneuver, under the thrust of the operating rod, the shoulder 301 abuts against the piston head 61 and the spring 8 is compressed: the gas present in the volume V1 is discharged via the channel opening 71 and the non-return valve 10. During an opening maneuver, under the pulling action of the operating rod, the shoulder 301 is no longer supported on the piston head 61 and the spring 8 is relaxes and exerts a push on the piston 6: a pressure difference is then installed between the volumes V2 and V1 (ie p2-p1> 0). These pressure forces increase with the displacement of the piston in the direction of thrust of the spring, and the whole reaches an equilibrium: the confinement position C ₀ is then reached, typically after a few millimeters of displacement. The pneumatic leakage present implies that the pressure p1 prevailing in the volume V1 then tends to join that p2 prevailing in the volume V2, but the spring 8 which relaxes maintains the difference p2-p1 positive. The piston 6 thus moves slowly until the hole 6010 has passed the place where the seal 67 is arranged. The pressure p1 then becomes equal to the pressure p2, there are no more pressure forces which oppose to the spring force of the spring 8: the piston 6 accelerates strongly and moves until it abuts against the shoulder 301.

In figure 3 , there is shown for a breaking chamber 1 according to the FIGS. 2A to 2C , the respective translation strokes of the movable contact 3 and the tubular nozzle 5. It can be seen in this figure that while the movable contact 3 realizes its stroke from F to O in a duration T1 of about 100 ms, a slight withdrawal of the nozzle 5 once the displacement of the contact 3 started (passage from the confinement position C to C0) until the balance of the forces of pressure on either side of the head 61 of the piston 6 that constitute the spring 8 and the pressures p1 and p2 respectively prevailing in the volumes V1 and V2.

Then for a further period of time ΔT, the nozzle 5 is removed simply because of pneumatic leakage, at a slow speed (about 1 cm / s): the nozzle 5 thus remains substantially close to its confinement position C, C ₀ in which allows the gas polluted by arc extinction (s) to be confined and discharged outside the electrical contact zone.

• réaliser une commutation du courant dans les transformateur-convertisseurs d'une sous station HVDC équipée d'un interrupteur by-pass équipé de la chambre de coupure ;
• vérifier pendant le laps de temps déterminé ΔT que tout courant a bien été coupé;
• réaliser une refermeture des contacts alors que la buse 5 est toujours maintenue sensiblement dans sa position de confinement C, C₀ (cette opération est représentée en pointillés sur la figure 3).

Thus, for an overall time of approximately 150 ms, the open position O is reached and the nozzle 5 remains in the insulating space e between the baffle hoods, which makes it possible to

• switching the current in the transformer-converters of a HVDC sub-station equipped with a by-pass switch equipped with the breaking chamber;
• check for the determined period of time ΔT that any current has been cut off;
• to make a reclosing of the contacts while the nozzle 5 is always maintained substantially in its confinement position C, C ₀ (this operation is shown in dashed lines on the figure 3 ).

If any current has actually been cut by the breaking chamber according to the invention, once this time ΔT + T1 passed (of the order of 150ms on the figure 3 ), and because of the pneumatic leakage present, the hole 6010 of the tube 60 passes below one of the seals 67 interposed between the piston tube 60 and the jacket 7 to reach a position corresponding to a position slightly to the right of that represented in figure 2b . The seal 67 under which the hole 6010 passes is the leftmost one on the Figures 2A, 2B and 2C ; it is also smaller in diameter than the one on the right in these figures. The seal 67 shown furthest to the right is the one that seals at the level of the piston head 61. The emptying of the insulating gas from the volume V2 to the volume V1 under vacuum can then occur because the insulating gas then follows the path next: volume V2- hole 6100-space between hollow tube 30 and part tube 60- hole 6010- volume V1. This therefore allows a passage of the insulating gas with a larger flow rate in the volume V1 with consequent movement of the nozzle 5 towards its withdrawal position R of the Figure 2C since under the combined action of the relaxation of the spring 8 and the introduction of large gas flow from the volume V2. In other words, the thrust on the piston head 61 is increased. It is therefore possible to achieve rapid retraction in a time T2 of the order of 850 ms and with speeds of the order of 1 m / s.

Thus, this mechanical thrust by the spring 8 makes it possible to reach the withdrawal position R of the tubular nozzle 5 very quickly. This also enables the HVDC control system to go up to full voltage more quickly, typically at least 400 kVDC for a chamber. according to the invention.

The displacement in translation of the piston 6 is stopped by the mechanical abutment of the head 61 on the shoulder 301 of the hollow tube 30 ( Figure 2C ).

A closing maneuver takes place in a strictly symmetrical manner ( FIG. 2C to FIG. 2A ). A thrust of the hollow tube 30 of the movable contact is made by the operating rod, which also pushes synchronously by mechanical stop 301, 61 the piston 6 blowing nozzle support 5. This maneuver compresses the gas present in the volume V1 which escapes through the nonreturn valve 10 in the volume V4. In the closed position F of the contacts 2,3 ( Figure 2A ), the volume V1 is reduced to just necessary to accommodate the return spring 8 in position of the piston 6 and the nozzle 5 it supports.

• l'absence d'isolants solides dans l'espace ou gap de longueur e,
• possibilité de réaliser un interrupteur by-pass HVDC avec un minimum de chambres de coupure en série, voire une seule chambre de coupure,
• possibilité de couper un courant de l'ordre de quelques 100A, voire 1000A et de tenir une tension de plusieurs centaines de kVcc avec une seule chambre de coupure,
• utilisation possible de matériaux isolants usuels pour la constitution de la buse, tels que le PTFE.

The invention as described has many advantages:

• the absence of solid insulators in the space or gap of length e,
• possibility of producing a HVDC bypass switch with a minimum of series breaking chambers, or even a single breaking chamber,
• possibility of cutting a current of the order of a few 100A or 1000A and to maintain a voltage of several hundred kVcc with a single breaking chamber,
• possible use of usual insulating materials for the constitution of the nozzle, such as PTFE.

Many modifications and improvements can be made without departing from the scope of the invention.

By construction, the interrupting chamber according to the illustrated embodiment, allows by pneumatic delay of the piston supporting the nozzle (that is to say a maintenance of the nozzle substantially of the nozzle in its confinement position C) to achieve a time ΔT of the order of 50ms. Those skilled in the art will easily adapt this latency of movement of the nozzle 5 once the open position reached according to the needs and in particular according to the technological means of verifying the effective breaking of the current. In other words, the lapse of time will be determined in such a way that it can be ascertained by ad hoc means that the current has not possibly been cut and to close the HVDC bypass switch equipped with the breaking chamber according to the 'invention.

Thus, in the embodiment shown, the shrinkage 304 of the passage section of the insulating gas allowing the pressure rise of the insulating gas during the opening from the inside of the hollow tube 30 is provided substantially close to the connection between the hollow tube 30 and the tulip contact part 3 itself, that is to say the part of complementary shapes with the fixed arc contact rod 2. Alternatively, it could be advantageous to provide a realization of the narrowing further upstream that is to say, closer to the fastener 300 with the operating rod, in particular at the opening 303 which allows the insulating gas to pass from the compression volume V3 towards the inside of the tube 30 The advantage of making the narrowing 304 substantially close to the connection between tube 30 and the tulip contact portion 31 itself is to maximize the volume V3: thus if the shrinkage 304 is made at (s) the opening (s) 303 the volume V3 will be less.

Similarly, if the covers corona represented generally have a cylindrical shape with their tips bent internally delimiting a circular opening in which the tubular nozzle according to the invention is slidably mounted closer to the diameter of said opening. Other geometrical shapes of screeds are quite conceivable: the insulating space of length e delimited between these covers of other shapes must be sufficient and the blowing nozzle must be able to be moved from a confinement position in which it confines the gas in an area dielectrically constrained to its retracted position in which it is removed from this space.

Similarly, if the illustrated embodiment represents a breaking chamber with a single moving contact (the tulip contact 3) it is quite possible to envisage carrying out the invention with a double movement of the contacts, it is that is to say make them separable mutually in the breaking chamber.

If the assembly adopted in the embodiment illustrated for the nonreturn valve 10 is made by a system of pins-spring bearing a ring against the contact door, it can also be considered to simplify the assembly when the chamber cutoff according to the invention must be arranged vertically, to place only a ring on the channel opening, the return of its open position to its position in support against the door contact of the ring is then made by fallout by gravity.

Claims (17)

1. An interrupting chamber (1) having a longitudinal axis (XX') and comprising:

   · a single pair of contacts (2, 3), at least one of which (3) is adapted to be moved in straight line motion along the longitudinal axis (XX') by an operating rod;

   · an insulating arc blast nozzle (5) of generally tubular form, which is also movable in straight line motion along the longitudinal axis (XX');

   wherein the or each moving contact (3) and the tubular nozzle (5) are movable independently of each other, said intempting chamber being characterized in that :

   · a pair of grading shields (40, 41) arranged with their respective shield walls (400, 410) separated from each other by a given fixed distance along the longitudinal axis (XX') so as to define an insulating space, said grading shields being arranged individually around each of the contacts of said single pair whatever may be their position; and

   · in the closed position of the contacts, the tubular nozzle is in a position referred to as the confinement position (C), in which it extends at least into said insulating space, having a length e, between the contacts (2, 3) and the shield walls (400, 410) of the grading shields (40, 41);

   · during an opening operation, the tubular nozzle (5) remains held substantially in its confinement position (C), at least until the or each moving contact has reached the open position (0);

   · once the opening operation is complete and all current broken, the tubular nozzle (5) is moved into a position referred to as the retracted position (R), in which it is retracted from said insulating space,

   wherein the nozzle is held, during an opening operation, in its confinement position by pneumatic pressure of the insulating gas of the chamber acting on the nozzle.
2. An interrupting chamber (1) according to claim 1, wherein the pneumatic pressure is exerted on a member (6) that is stationary relative to the nozzle (5) and configured as a piston, said piston (6) being mounted in a stationary member that constitutes the contact carrier (7), for sliding movement around one of the moving contacts (3, 30).
3. An interrupting chamber (1) according to claim 1 or claim 2, wherein the movement of the nozzle (5) towards its retracted position (R) from said insulating space takes place after a determined lapse of time after the instant in which the contacts (2, 3) become fully open.
4. An interrupting chamber (1) according to claim 3, wherein the lapse of time is so determined that it is possible to perform an operation of closing the moving contact or contacts (3) when the nozzle is held in its confinement position (C) and there is still current to be broken.
5. An interrupting chamber (1) according to claim 4, wherein said lapse of time is of the order of 100 ms.
6. An interrupting chamber (1) according to any of claims3 to 5, wherein the movement of the nozzle towards its retracted position from said insulating space is performed by a compression spring (8), one end of which is stationary, its other end being coupled to a member (6) that is itself stationary relative to the movable nozzle (5), the expansion of the spring (8) to the retracted position (R) of the nozzle (5) being performed after the determined lapse of time.
7. An interrupting chamber (1) according to any of claims 2 to 6, wherein the compression spring (8) is disposed within a variable volume V1 that is defined between the piston (6) and the contact carrier (7).
8. An interrupting chamber (1) according to claim 7, wherein one of the moving contacts (3, 30) has a shoulder (301), and wherein the contact carrier (7) includes, in the region of the volume V1, a through channel (71) over which a non-return valve (10) is mounted, the insulating gas present in the volume V1 being:

   · evacuated, in a closing operation, by the action of the piston (6) in mechanical abutment against the shoulder (301) of the moving contact (3), through the channel (71) and the non-return valve (10) in an open condition of the channel, so that the volume V1 is reduced to the minimum value needed to accommodate the spring in its compressed state; and

   · maintained at its minimum amount, in an opening operation, during a lapse of time that is determined, except for any pneumatic leaks that might occur either between the piston and contact carrier or between the non-return valve and the contact carrier, under the action of the pressure prevailing in a volume V2 defined between the contact carrier (7) and the moving contact (3) on the side of the piston opposite from the side on which the spring is located, the difference between the pressures prevailing in the volumes V2 and V1 compensating for the thrust force exerted by the spring (8) compressed against the piston (6, 61) during said determined lapse of time.
9. An interrupting chamber (1) according to claim 8, wherein:

   · the tube portion (60, 601) of the piston (6), which joins the piston head (61) to the nozzle (5), is spaced away from the moving contact, and has a through hole (6010);

   · the piston head (61), between the moving contact (3) and the tube portion (60, 601) of the piston, has a further through hole (6100) between the volumes V1 and V2, the through hole (6010) of the tube portion (60) of the piston being arranged in such a way that, after said determined lapse of time, the pneumatic leaks have brought the piston (6) into a position that enables gas from the volume V2 to penetrate into the volume V1 through the through holes (6010, 6100), which accelerates the movement of the nozzle (5), fastened to the piston (6), towards its retracted position.
10. An interrupting chamber according to any preceding claim, wherein both contacts are movable, transmission means being arranged in the chamber for separating the contacts from each other.
11. A high voltage interrupter including an interrupting chamber according to any preceding claim.
12. An interrupter according to claim 11, constituting a circuit breaker or a busbar disconnector or a grounding disconnector.
13. An interrupter having an interrupting chamber (1) according to any preceding claim and constituting an HVDC bypass interrupter.
14. An HVDC interrupter according to claim 13 having a single circuit-breaker chamber (1).
15. An HVDC interrupter according to claim 14, wherein the current to be broken by said chamber is able to reach several hundred Amp, or even 1000 A, and the voltage withstood by said chamber is able to reach at least 400 kV in direct current.
16. An HVDC conversion substation including at least one HVDC bypass interrupter according to any one of claims 13 to 15.
17. An HVDC conversion substation according to claim 16, wherein the axes of the current breaker chamber of the interrupter is substantially vertical.

Images