EP2237300B1 - Interrupting chamber with mobile contact having interior arc-blowing provision, HVDC bypass interruptor and HVDC-conversion substation with such a 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 blowing of gas 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

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 toute 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 HVDC bypass switch is to constitute a bypass of each converter transformer to which it is connected. 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 de 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 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 conduit 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- Many materials, such as PTFE, have been tested as a component of AC high voltage discharge nozzles. 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 that interface between the insulating gas and the insulating material. 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 leads 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.

Also, the plaintiff proposes in the patent application FR 0952173 entitled "movable contact cutoff chamber and independently operated mobile blow nozzle, switch bypass HVDC and substation HVDC converter including such a chamber" and filed on the same day as the present application, a solution that allow to obtain an HVDC bypass switch with reduced space and cost.

The gas blowing problem then arose for the inventors since, in the cut chambers according to the state of the art, blow molding is carried out radially in contact with one or more channels delimited by construction between the nozzle. blowing and the contact between them.

The inventors then thought to perform the blowing integrally from the inside of one of the contacts. In fact, blowing integrally from the inside of one of the contacts makes it possible to adapt the tubular nozzle (according to the patent application filed on the same day and mentioned above) as close as possible to the outside diameter of the tulip. This contributes to the best containment of gases polluted by the arcs inside the nozzle and their evacuation outside the contact area. It is thus possible to achieve a tubular nozzle with a height (that is to say a minimum radial size), which allows a better dielectric coordination between corona shielding and arc electrical contacts.

The patent FR 2,695,249 already discloses arc blowing through the interior of a movable arc contact 8, 9. In this patent, the tulip contact 9 by which blowing is performed is fixed and the hollow tube 8 which supports this contact. 9 and through which the gas passes is obstructed mainly by an insulator 10.

The disadvantage of this patent is that the implantation of the insulator 10 with respect to the hollow tube 8 is such that the passage section of the weakest blowing gas is at the end of the tulip 9. therefore has a significant risk of low gas density, and therefore dielectric strength at the transient recovery voltage, at the end of the arc contact which is the area in which the strongest dielectric gradients develop. The DE 1 908 774 describes all the features of the preamble of claim 1.

The object of the invention is then to propose a gas blowing solution integrally from the arc contact interior of an interrupting chamber which is efficient and which allows it to have a good dielectric strength at the transient voltage. Recovery Strategy (TTR).

STATEMENT OF INTENT

• le soufflage d'arc est réalisé intégralement par l'intérieur du tube creux selon l'axe longitudinal de la chambre,
• un rétrécissement de passage des gaz, de section S2, est prévu en amont de la partie contact proprement dite,
• un élargissement de passage des gaz, de section S3, est prévu entre le rétrécissement et la partie contact proprement dite, les sections étant telles que S2<S1<S3.

To achieve this object, the invention provides a current-breaking chamber extending along a longitudinal axis and comprising an arc-blowing nozzle and a pair of contacts including at least one mobile, one of which comprises a tube internally. hollow with one end connected to the actual contact part, chamber in which the arc blowing is carried out integrally from the inside of the hollow tube along the longitudinal axis of the chamber, a narrowing of the gas passage section being provided in upstream of the actual contact part, section S1. In this breaking chamber according to the invention, it is provided that:

• the arc blowing is carried out integrally from the inside of the hollow tube along the longitudinal axis of the chamber,
• a narrowing of the gas passage, section S2, is provided upstream of the contact part itself,
• a widening of the gas passage, section S3, is provided between the narrowing and the actual contact part, the sections being such that S2 <S1 <S3.

This avoids making an area of low gas density near the actual contact area which is the most exposed to the electric fields after cutting.

The interrupting chamber thus designed has good dielectric strength at the transient recovery voltage (TTR).

In the context of the invention, the terms "upstream" and "downstream" are to be understood in relation to the direction of flow of the blowing gases to cut an arc.

By completely blowing from the inside of the contact tube, it is necessary to include a blowing of all the gases coming from the compression volume from the inside of the contact tube towards the outside thereof.

Advantageously, the enlargements of the passage of the blowing gases, of section S2 and S3, are dimensioned so that during any opening under normal operating conditions of the switch provided with the interrupting chamber, the pressure of the blowing gases does not reach the critical pressure, the critical pressure being the pressure at which the low density zone of the gases downstream of the expansion remains contained downstream of the section S1 passage of the actual contact part. In other words, it is necessary to provide a widening of the gas passage which does not generate a low density of the gases in the actual contact part or slightly outside thereof.

As indicated below, the abnormal conditions being defined as those occurring during an additional electrical fault simultaneously with the opening of the contacts, this additional electrical fault occurring either on a different electrical component or on electrical equipment different from the switch with the interrupting chamber. Thus, as mentioned below, in the case of an HVDC substation comprising a switch provided with a breaking chamber according to the invention and thyristors, the additional electrical fault is the fault of commutation of the thyristors to avoid an unexpected re-closing of the contacts.

According to one embodiment, the narrowing can be achieved in the connection between the inner hollow tube and the actual contact part.

According to another embodiment, the shrinkage may be carried out in one or more openings for feeding the gas into the hollow tube.

• il ne s'ouvre pas, lors de toutes manoeuvres d'ouverture en conditions anormales de fonctionnement l'interrupteur muni de la chambre de coupure,
• il commence à s'ouvrir à la pression critique qui est la pression à laquelle la zone de faible densité des gaz est présente en aval de la section S1 de passage de la partie contact proprement dite,
• il s'ouvre à son maximum, lors de manoeuvres d'ouverture en conditions anormales de fonctionnement de interrupteur muni de la chambre de coupure, les conditions anormales étant définies comme celles se produisant lors d'un défaut électrique supplémentaire simultanément au défaut électrique provoquant l'ouverture des contacts, ce défaut électrique supplémentaire ayant lieu soit sur un composant électrique différent ou sur un appareillage électrique différent de l'interrupteur muni de la chambre de coupure.

The blowing volume until the shrinkage is advantageously closed by a valve called relief valve whose setting is made so that:

• it does not open, during all opening maneuvers in abnormal operating conditions, the switch equipped with the interrupting chamber,
• it begins to open at the critical pressure, which is the pressure at which the zone of low density of the gases is present downstream of the passage section S1 of the contact part itself,
• it opens at its maximum, during opening operations in abnormal operating conditions of switch equipped with the interrupting chamber, the abnormal conditions being defined as those occurring during an additional electrical fault simultaneously with the electrical fault causing the opening of the contacts, this additional electrical fault occurring either on a different electrical component or on electrical equipment different from the switch provided with the interrupting chamber.

It is quite possible according to the invention to provide that the two contacts are mobile, transmission means between contacts for mutually separating the contacts being provided in the bedroom. 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 up to 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.

According to a characteristic of an HVDC substation comprising thyristors, the maximum opening of the rating valve is realized in case of Failure to switch thyristors to prevent unexpected re-closing of contacts.

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 position of opening 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

It is recalled here that the terms "upstream" and "downstream" are to be understood in relation to the direction of flow of the blowing gases to cut an arc.

Thus, during an opening operation of the switch provided with a breaking chamber according to the invention, the upstream of the blowing on the FIGS. 2A to 2C takes place in volume V3 up to the extreme downstream, that is from right to left.

With reference to the arc contact 3, the hollow tube 30 is upstream of the narrowing 304 of the gas passage section, itself upstream of the expansion 305 in the immediate continuity of 304, the latter 305 being upstream immediately of the contact part 31 itself.

The gas passage sections S1, S2, S3 respectively of the actual contact portion 31, the narrowing 304 and the enlargement 305 are the flow sections of the blowing gases.

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 curve representative of the voltage of a 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 a HVDC conversion substation, including a bypass switch HVDC is connected.

Consequently, unlike the alternating current which can be naturally cut off at zero current, the difficulty of breaking DC is due to the fact that a zero current appears several times during switching, 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 ensures 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 SF6 + nitrogen mixture ... The chamber 1 comprises, all first 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 an internally hollow tube 30 coupled directly to a translational actuating rod at a fastener 300. At the free end, the tube 30 is connected to the actual contact part 31 at the end. shape of a tulip of inner shapes complementary to those outside the fixed arc rod 2. The hollow tube 30 also has a narrowing of outer shapes defining a shoulder 301. On its widened part, a flange 302 forming a piston ( as explained later) is fixed 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 below.

This interrupting chamber 1 further comprises a pair of horn covers 40, 41 whose primary function is to cancel at the very least reduce the peak effect at the contacts (or to tip contacts, the electric field tends to tend towards infinity, which can contribute to the ionization of gas and thus the initiation of a possible electric arc). The respective end pieces 400, 410 of each cap delimit circular openings and are spaced apart by 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 whatever 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 inside diameter Ø of the nozzle 5 is preferably adjusted to the outside 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 internally hollowed with several different diameters in continuity of one another. An end 600 of this piston tube 60 has an inner diameter allowing the internal 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 that of 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 6 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 of which the turns are wrapped around the tube part 60, 600, 601 as explained by oozing. 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 in the chamber does not 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 302 piston housing at its periphery an electrical contact shape 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 flange piston 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 the hinge as tight as 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 through the inside of the hollow tube 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 ring 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 if 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 of the valves 92 has the opposite function, when open to allow the shedding 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 pawn or 910 of travel of the valve 91 filling is represented in 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 holder 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 on the other hand on the volume V4 delimited by the corona cover 41 and the contact door 7 to which it is attached. On this opening 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 holds in position the piston 6 and therefore 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 contact door 7: it can just as well be beyond the contact door 7 and lead into the frozen volume V4.

When an opening maneuver of the bypass switch HVDC including the breaking chamber 1 according to the invention is triggered, the hollow tube 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 a rise in pressure of the volume of gas that extends from the ring 9 to the internal narrowing 304 of the hollow tube 30 of the movable contact 3, that is to say say substantially corresponding 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 internal volume of the hollow tube 30, that is to say until the narrowing section gas passage 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. In fact, the inventors started from the observation that a drop in The density of the insulating gas was detrimental as the dielectric strength decreased 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 it can occur a drop in gas density from the smallest gas passage section. If this drop is too great it occurs at the actual contact part 31 (tulip) and the dielectric strength 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 narrowing of section 304 eh upstream of the tulip portion 31. This narrowing 304 is of flow section S2 less than that of the tulip and can be an integral part of the hollow tube 30 or be constituted by a insert for example by screwing at the end of hollow tube. It has also been designed downstream of the constriction 304 and upstream of the tulip 31, an enlargement 305 of the blowing section, S3, greater than the blow section S1 of the tulip 31.

In addition, the critical pressure not to be exceeded according to the invention is that at which a zone of low gas density would extend beyond the wide passage section S3, that is to say the enlargement 305, which is immediately downstream of the narrowing 304 and, consequently, immediately outside the end of the tulip 31. In the application according to the invention, the wide section S3 of so that during any normal opening the pressure does not reach the critical pressure and the relief valve 92 is adjusted to open beyond the critical pressure. Under these conditions, no zone of low gas density is established downstream of the tulip 31.

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 of 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. During this opening under abnormal conditions, a rise in pressure may then occur in the space e and consequently in the volume V3 in a direction opposite to the direction of blowing (that is 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.

• ne s'ouvre pas, lors de toutes manoeuvres d'ouverture en conditions normales de l'interrupteur muni de la chambre de coupure,
• commence à s'ouvrir à la pression critique à laquelle la zone de faible densité pourrait s'étendre au-delà de la section S3, 305 de passage large en aval du rétrécissement 304,
• s'ouvre à son maximum, lors de manoeuvres d'ouverture en conditions anormales 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 relief valve 92 so that it:

• does not open, during any opening operation under normal conditions of the switch equipped with the interrupting chamber,
• begins to open at the critical pressure at which the low density zone could extend beyond section S3, 305 of wide passage downstream of narrowing 304,
• opens at its maximum, during opening maneuvers in abnormal conditions 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.

Pneumatic leakage 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 with respect to its position. initial 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 nozzle 5 blowing remains substantially in its confinement position (position C on the Figure 2A and position C ₀ 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, whatever 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 actuating rod, the shoulder 301 bears against the piston head 61 and the spring 8 is compressed: the gas present in the volume V1 is discharged via the opening channel 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 expands and exerts a thrust 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 removal of the nozzle 5 once the movement of the contact 3 has begun (passage from the confinement position C to C0) until the equilibrium of the pressure forces on either side of the head 61 of the piston 6 that constitute the spring 8 and the pressures p1 and p2 prevailing respectively in 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 it allows the gas polluted by extinction arc (s) to be confined and evacuated outside the electrical contact area.

• 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).

Therefore, for an overall time of about 150 ms, the open position O is reached and the nozzle 5 remains in the insulating space e between corona caps, which allows:

• switching the current in the transformer-converters of a HVDC substation equipped with a by-pass switch equipped with the interrupting chamber,
• check for the determined period of time ΔT that any current has been cut,
• 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 tube 60 of pistou 6 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 insulating gas from volume V2 to volume V1 under vacuum can then occur because the insulating gas then follows the following path: volume V2-hole 6100-space between hollow tube 30 and 60-hole tube portion 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 closing 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-pas 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 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 by-step switch with a minimum of series breaking chambers, or even a single breaking chamber,
• ability to cut a current of the order of a few 100A or 1000A and to hold a voltage of several hundred 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 reach a time lapse ΔT of the order of 50 ms. 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 cutting verification effective 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 portion 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 to 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 narrowing 304 is made at (s) the opening ( s) 303 the volume V3 will be smaller.

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 at 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 disengaged position to its position in abutment against the contact door of the ring then being made by fall by gravity.

Claims (13)

1. An interrupting chamber (1) having a longitudinal axis (XX') and including an arc blast nozzle (5) and a pair of contacts (2, 3), at least one (3) of which is movable,
   characterised in that
   one of said contacts (3) comprising a tube (30) with a hollow inside having one end coupled to the contact portion proper (31), which has a flow cross section S1, wherein, in said chamber:

   • arc blowout is performed entirely through the inside of the hollow tube (3) along the longitudinal axis of the chamber;

   • a constriction (304) in the flow path of the gases, having a flow cross section S2, is disposed upstream from said contact portion proper (31); and

   • a wider portion (305) of the flow path of the gases, having a flow cross section S3, is disposed between the constriction (304) and the contact portion proper (31), the flow cross sections being such that S2 < S1 < S3.
2. An interrupting chamber according to claim 1, wherein the cross sections S2 and S3, are so dimensioned that, during any opening operation under normal conditions of operation of the interrupter that includes the current blowout chamber, the pressure of the blowout gases does not reach a critical pressure, said critical pressure being the pressure to which the zone of low gas density downstream from said wider portion (305) remains restricted downstream from the flow cross section S1 of the contact portion proper (31).
3. An interrupting chamber (1) according to claim 1 or claim 2, wherein the constriction (304) is located at the junction between the tube (30) that has said hollow inside and the contact portion proper (31).
4. An interrupting chamber (1) according to any preceding claim, wherein the constriction (304) is located at at least one through hole (303) for bringing gas into the hollow tube (30).
5. An interrupting chamber (1) according to any preceding claim, wherein the blowout volume as far as the constriction is obturated by a flap valve referred to as a bleed valve (92), which is preloaded in such a way that:

   • it does not open in any normal opening operation under normal conditions of operation of the interrupter that includes the interrupting chamber;

   • it begins to open at the critical pressure, said critical pressure being the pressure to which the zone of low gas density is present downstream from the flow cross section S1 of the contact portion proper (31); and

   • it opens to its maximum amount during opening operations under abnormal conditions of operation on the interrupter that includes the interrupting chamber, said abnormal conditions being defined as the conditions that occur when there is an additional electrical fault simultaneously with opening of the contacts (2, 3), such additional electrical fault taking place either on a different electrical component or on a different electrical device of the interrupter that includes the interrupting chamber (1).
6. A high voltage interrupter including an interrupting chamber according to any preceding claim.
7. An interrupter according to claim 6, constituting a circuit breaker or a busbar disconnector or a grounding disconnector.
8. An interrupter having an interrupting chamber (1) according to claim 5 and constituting an HVDC bypass interrupter.
9. An HVDC interrupter according to claim 8 having a single interrupting chamber (1).
10. An HVDC interrupter according to claim 9, wherein the current to be broken by said chamber is able to reach several hundred A, or even 1000 A, and the voltage withstood by said chamber is able to reach at least 400 kV in direct current.
11. An HVDC conversion substation including at least one HVDC bypass interrupter according to any one of claims 8 to 10.
12. An HVDC conversion substation according to claim 11, wherein the axes of the current breaker chamber of the interrupter is substantially vertical.
13. An HVDC conversion substation according to claim 11 or claim 12 including thyristors, wherein the bleed valve (92) is opened fully in the event of a switching fault in the thyristors, in order to avoid unexpected reclosing of the contacts (2, 3).

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