EP1211706A1 - High tension switchgear with double mouvement - Google Patents

Abstract

The high tension circuit breaker includes two contact separating devices linked by a transmission mechanism. The mechanism includes a cam linkage, such that the two contact separating devices move at different speeds, the ratio of their two speeds changing during the course of the movement between an initial value of 0.5 and a maximum value of 1.2. The high tension circuit breaker comprises a first contact device (12) driven by a drive mechanism (14), and a tube (16) solidly attached to the first contact device. A second contact device (18) is mechanically linked to the tube by a transmission mechanism (20) with a cam (84). This linkage ensures a variable speed ratio (V2/V1) between the first and second contact devices. The ratio (V2/V1) is less than 0.5 when the first switch is close to its open position increasing to a maximum value of 1.2 near to the point of separation of the contacts, then reducing to 0.5 again.

Description

TECHNICAL FIELD OF THE INVENTION

The invention relates to a double high voltage electrical switchgear movement of contacts.

STATE OF THE ART

We know switchgear on load, switches, disconnectors or circuit breakers, for high voltage and in particular for very high voltage, comprising two separable aligned contacts and a control mechanism causing displacement in translation of one of the contacts relative to the other.

It has been proposed in document FR 1 448 854 to provide two movable contacts in translation in a sealed enclosure. A first contact is driven by a mechanism of control and is provided with a means of driving the second contact, to cause a uniform movement of the two contacts at the start of the opening stroke, so that the contacts do not separate immediately. Positive unlocking means cause the separation of the two contacts at a predetermined place in their course and a return spring drives the second contact to its original position while the first contact continues its course after the separation of the two contacts. Such a device offers the advantage of increasing the separation speed of the contacts for a stroke of given separation, so as to quickly lengthen the emerging electric arc between the contacts at the time of their separation. But it requires a drive mechanism powerful, since it must take charge, at the start of the opening race, compression of the return spring. In addition, the stroke of the second contact after the separation is completely independent of that of the first contact, since it no longer exists mechanical connection between the contacts beyond the separation position. In case of malfunction of the mechanism for returning the second contact to its rest position, it may happen that the second contact remains stuck in its intermediate position of separation, while the first contact is driven by the mechanism drive control to its open position. In this case, the drive control indicates a sectioning position, when in fact the disconnection distance is not respected.

In the document US 3 896 282 is described an electrical switchgear comprising a sealed envelope filled with dielectric gas. A first and a second movable contacts are positioned in the envelope and are normally engaged one in the other to allow the passage of current. To open the contacts and interrupt the current, a mechanism with connecting rods and crank allows to simultaneously drive the two contacts in opposite directions with respect to the envelope, with equal speeds. The separation speed is higher than in switchgear only allowing movement of only one of the two contacts. In addition, the connecting rod mechanism and crank ensures a mechanical connection between the first and the second at all times contact so the position of the second contact is always related to the position of the first contact and that of the drive mechanism. However, the power required, especially at the start of the opening, is important because it is necessary to train at all moment the two moving masses formed by the two contacts. In addition, this device does not have arcing contacts, which makes it inapplicable to switchgear high performance. Finally, the rods of the deflection mechanism pose a problem space inside the waterproof envelope.

In document EP 313 813 a high voltage electric switch is described comprising a sealed envelope filled with a dielectric gas and containing a member mobile contact and a fixed contact member. The mobile contact member includes a permanent contact and an arcing contact integral with each other, as well as a nozzle in insulating material fixed to permanent contact. The mobile contact member is driven axially in translation in the envelope by a drive mechanism. The organ of fixed contact comprises a permanent contact which is fixed relative to the envelope, and a arc contact sliding axially in a sliding contact making the electrical connection with fixed permanent contact. A rack and pinion transmission mechanism allows to transmit to the sliding arc contact of the fixed contact member, the translational movement of the movable contact member. The arcing contact of the organ of fixed contact in a tubular form so that when the switch is closed, the contact of the movable contact member penetrates deep into the arcing contact of the member fixed contact. When the switch opens, the movable permanent contact separates of the fixed permanent contact before the arcing contacts separate. When the separation of arcing contacts, these are driven relative to each other with a speed which is twice the speed of the mobile permanent contact compared to the contact permanent fixed. This device makes it possible to limit the mass in movement, since one of the permanent contacts remains fixed relative to the envelope. However, it requires a drive mechanism having a large stroke, since the cutting distance between the permanent contacts in the open position is obtained only by the displacement of the mobile permanent contact.

In document DE 196 31 323, an apparatus derived from the preceding is described. The switch has a first contact member and a second contact member. The first contact member comprises a permanent contact, an arcing contact and a nozzle made of insulating material forming a monobloc assembly mu directly by a drive mechanism. The second contact member has a permanent contact and an arcing contact integral with each other. The movement of the arc contact of the first contact member is transmitted to the second contact member via a transmission mechanism comprising a movement reversing lever, a first connecting rod articulated on the nozzle and on the lever, and a second connecting rod articulated on the second contact member and lever. When the switch opens, the arcing contacts separate with opposite speeds, the modules of which are equal. Mass in motion is important since it includes the two arcing contacts and the two permanent contacts. The drive mechanism must be dimensioned accordingly. One of the trials of Critical cut is a low current capacitive current cut test. For cut off such current, the distance between the arcing contacts must increase very quickly to from their separation, while to cut short-circuit currents, it suffices reach a contact distance in less than half a period of the current, and wait for the current to pass through zero. The device does not allow optimization of kinetic energy in this case.

Document US Pat. No. 5,578,806 describes a switch comprising a first member contact and a second contact member. The first contact member includes a permanent contact, an arcing contact and a nozzle of insulating material forming an assembly monobloc moved directly by a drive mechanism. The second organ of contact comprises a permanent contact and an arcing contact integral with each other. The movement of the arcing contact of the first contact member is transmitted to the second member contact via a transmission mechanism comprising a toothed wheel transmission, a rack fixed to the nozzle and meshing with the toothed wheel, and a connecting rod articulated on the one hand at a point on the circumference of the wheel and on the other hand on the second contact body. The transmission mechanism is non-linear, which makes it possible to impose a low speed on the second contact member at the start of movement, during the separation of permanent contacts, to rapidly increase the speed when the arcing contacts separate, then slow the speed down opening. It thus becomes possible to cut the capacitive currents without spending a too much motor energy. However, the device does not optimize kinetic energy of the system.

In document EP 809 269 is described an apparatus comprising a first member for contact consisting of a permanent contact, an arcing contact and an insulating nozzle forming a one-piece assembly directly driven by a drive mechanism, and a second contact member comprising a fixed permanent contact, an arcing contact and a dielectric screen. A transmission mechanism connects the nozzle to the arcing contact of the second contact body. This transmission mechanism includes a reversing lever movement, a connecting rod connecting the lever to the arcing contact and a rod fixed to the nozzle and sliding in a straight groove of the lever. The transmission mechanism is no linear in the sense that the ratio between the speed of the nozzle and the speed of the arcing contact of the second contact member is not constant. However, during the entire race the nozzle speed remains much higher than the arcing contact speed of the second contact member, while the mass in motion secured to the nozzle, which also includes the first contact member, is much greater than the mass in movement integral with the arcing contact of the second contact member. Overall, the kinetic energy of the mechanism is not optimized during opening.

Document FR 2 491 675 describes a circuit breaker of the self-blowing and self-compression type comprising a first contact member consisting of a permanent contact, an arcing contact and an insulating nozzle forming a one-piece driven assembly directly by a drive mechanism, and a second contact member comprising a fixed permanent contact and an arcing contact. A transmission mechanism connects the nozzle to the arcing contact of the second contact member. The first organ of contact forms a cylinder opening towards the nozzle by small diameter conduits, and closed on the opposite side by a fixed piston, so as to constitute a blowing chamber of variable volume. When the first contact member moves, the piston enters the blowing chamber and the volume of the chamber decreases. At the start of the opening, so many that the second arcing contact plugs the nozzle opening, the movement of the first contact member causes an increase in pressure in the blowing chamber. As soon as the arcing contacts separate, the second arcing contact releases the orifice of the nozzle. The volume of the blowing chamber continues to decrease and the gases escape of the blowing chamber through the orifice, helping to extinguish the incipient arc between the arcing contacts. In the case of an opening on a strong current, the blowing must imperatively continue in order to continuously bring the gases relatively costs contained in the blowing chamber, and this until the arc is extinguished. In others In other words, the action of the piston is necessary during the entire opening movement. Speed of the first contact member with respect to the piston must therefore be sufficient for the pressure in the blowing chamber remains higher than the pressure at the nozzle. In this document, it has been proposed to implement a transmission mechanism giving the contact carrying the nozzle a speed less than or equal to the speed of the contact not carrying the nozzle, in order to decrease the kinetic energy of the system. The report of speeds remains constant during the opening stroke, which is well suited to the needs of this type of circuit breaker, and in particular the need to blow continuously by compressing the blowing chamber. However, teaching this document is difficult transposable to a circuit breaker comprising a compression piston. In this case, in fact, it is necessary to obtain a high piston speed on the one hand at the start of the stroke opening to rapidly increase the pressure in the arc expansion chamber, and on the other hand at the end of the opening stroke, to blow the arc more effectively. As the piston is usually secured to the contact supporting the nozzle, it is he who imposes the nozzle speed.

STATEMENT OF THE INVENTION

The invention therefore aims to remedy the drawbacks of the state of the art, so as to propose a high voltage switchgear with compression effect, which is efficient and which allows to obtain a fast and reliable opening, in a volume restricted and with reduced maneuvering energy.

• un support fixe délimitant un volume de compression,
• un premier organe de contact mobile par rapport au support et comportant :
  • un premier contact permanent,
  • une tuyère en matériau électriquement isolant, solidaire du premier contact permanent,
  • un piston solidaire du premier contact permanent et coulissant dans le support, de manière à délimiter avec la tuyère un volume d'expansion d'arc, et à séparer le volume d'expansion d'arc du volume de compression, le piston étant muni d'une soupape de refoulement du volume de compression vers le volume d'expansion d'arc, qui s'ouvre lorsque le volume de compression est en surpression par rapport au volume d'expansion d'arc,
  • un premier contact d'arc solidaire du premier contact permanent et faisant saillie à l'intérieur du volume d'expansion d'arc ;
• un deuxième organe de contact comportant un deuxième contact permanent et un deuxième contact d'arc mobile par rapport à l'enceinte ;
• un mécanisme d'entraínement pour entraíner le premier organe de contact d'une position fermée à une position ouverte avec un mouvement de translation axiale le long de l'axe de référence, en passant par une position fugitive de séparation des premier et deuxième contacts permanents P₂ dans laquelle les premier et deuxième contacts permanents perdent contact l'un avec l'autre, et en passant par une position fugitive de séparation des premier et deuxième contacts d'arc P₃ dans laquelle les premier et deuxième contacts d'arc perdent contact l'un avec l'autre, située entre la position fugitive de séparation des premier et deuxième contacts permanents P₂ et la position ouverte ;
• un mécanisme de transmission constituant une liaison cinématique permanente entre la tuyère et le deuxième contact d'arc pour transmettre un mouvement de la tuyère au deuxième contact d'arc, le mécanisme de transmission étant tel que lorsque le premier organe de contact se déplace axialement dans un sens avec une vitesse ayant un module V ₁, le deuxième contact d'arc se déplace en translation suivant l'axe de référence en sens opposé avec une vitesse ayant un module V ₂ qui est dans un rapport V ₂/ V ₁ avec le module V ₁, le rapport V ₂/ V ₁ étant variable en fonction de la position du premier organe de contact par rapport à l'enceinte de telle manière que :
  • le rapport V ₂/ V ₁ reste inférieur à une valeur de 0,5 tant que le premier organe de contact se trouve entre la position fermée et une première position indexée P₁ située entre la position fermée et la position fugitive de séparation du premier et du deuxième contact d'arc P₃,
  • le rapport V ₂/ V ₁ passe par une valeur maximale supérieure à 1 lorsque le premier organe de contact passe par une deuxième position fugitive indexée P₅ située entre la position fugitive de séparation des premier et deuxième contacts permanents P₂ et la position ouverte,
  • le rapport V ₂/ V ₁ reste inférieur à une valeur de 0,5 tant que le premier organe de contact se trouve entre une troisième position indexée P₇ située entre la deuxième position indexée P₅ et la position ouverte d'une part, et la position ouverte d'autre part.

According to the invention, this objective is achieved by means of a high voltage load cut-off electrical apparatus comprising, inside a sealed enclosure filled with a gas with high dielectric strength and defining a geometric reference axis:

• a fixed support delimiting a compression volume,
• a first contact member movable relative to the support and comprising:
  • a first permanent contact,
  • a nozzle of electrically insulating material, secured to the first permanent contact,
  • a piston secured to the first permanent contact and sliding in the support, so as to define with the nozzle an arc expansion volume, and to separate the arc expansion volume from the compression volume, the piston being provided with '' a discharge valve from the compression volume to the arc expansion volume, which opens when the compression volume is overpressure relative to the arc expansion volume,
  • a first arcing contact integral with the first permanent contact and projecting inside the arcing expansion volume;
• a second contact member comprising a second permanent contact and a second arcing contact movable relative to the enclosure;
• a drive mechanism for driving the first contact member from a closed position to an open position with an axial translational movement along the reference axis, passing through a fleeting position of separation of the first and second permanent contacts P ₂ in which the first and second permanent contacts lose contact with each other, and passing through a fleeting position of separation of the first and second arcing contacts P ₃ in which the first and second arcing contacts lose contact with each other, located between the fleeting position of separation of the first and second permanent contacts P ₂ and the open position;
• a transmission mechanism constituting a permanent kinematic connection between the nozzle and the second arcing contact for transmitting a movement of the nozzle to the second arcing contact, the transmission mechanism being such that when the first contact member moves axially in one direction with a speed having a module V ₁ , the second arcing contact moves in translation along the reference axis in the opposite direction with a speed having a module V ₂ which is in a ratio V ₂ / V ₁ with the module V ₁ , the ratio V ₂ / V ₁ being variable as a function of the position of the first contact member with respect to the enclosure so that:
  • the ratio V ₂ / V ₁ remains less than a value of 0.5 as long as the first contact member is between the closed position and a first indexed position P ₁ located between the closed position and the fugitive position for separating the first and of the second arcing contact P ₃ ,
  • the ratio V ₂ / V ₁ passes through a maximum value greater than 1 when the first contact member passes through a second indexed fugitive position P ₅ located between the fugitive separation position of the first and second permanent contacts P ₂ and the open position,
  • the ratio V ₂ / V ₁ remains below a value of 0.5 as long as the first contact member is between a third indexed position P ₇ located between the second indexed position P ₅ and the open position on the one hand, and the open position on the other hand.

The reliability of the device is due to the fact that the kinematic link provided by the mechanism transmission is permanent, so that the position of the first contact member and the position of the operating mechanism give a true picture of the position of the second arcing contact.

The gear ratio imposed between the closed position and the first fleeting position indexed allows rapid acceleration of the first contact member, which is the heaviest, at the very beginning of the opening, before the separation of the arcing contacts. It therefore allows devote all available energy to driving the piston, which works for compress the gas contained in the compression volume. As soon as the pressure in the compression volume increases, the discharge valve opens, allowing also the pressure build-up of the arc expansion volume. When the separation takes place arcing contacts, the pressure in the arcing expansion volume is already high, which is favorable for breaking capacitive currents. Indeed, we know that the disruptive tension between two electrodes brought to different potentials in a given gaseous medium, i.e. the minimum voltage necessary for an electric arc to appear between the electrodes in the gaseous medium considered, is a function of the product of the pressure of the gas by the distance between the electrodes, given by Paschen's law, and that beyond of a minimum value, this function increases with the product of the pressure by the distance. By increasing the pressure in the expansion volume, the tension is therefore increased disruptive and avoids the breakdown of an arc between the arcing contacts.

The gear ratio imposed during the passage of the first contact member through the second indexed fugitive position makes it possible to significantly reduce the energy of the mobile assembly at a time when the speed acquired by the piston is sufficient and when it is useful to rapidly increase the distance between the arcing contacts. Indeed, if we consider on the one hand a first mobile assembly constituted by the masses in movement integral with the first contact, and on the other hand a second mobile assembly constituted by the masses in movement integral with the second arcing contact, it can be seen that the first moving part has a mass M ₁ higher than the mass M ₂ of the second moving part. This is explained by the fact that the first contact is secured on the one hand to the nozzle and on the other hand to a part of the drive control mechanism. By imposing on the speed V ₂ of the second contact to exceed the speed V ₁ of the first contact, the kinetic energy of the entire moving mass is reduced. A separation speed V ₁ + V _{2 is} thus obtained with very good energy efficiency. This arrangement is particularly advantageous for avoiding an arc breakdown in the event of a capacitive current cut-off test.

The gear ratio imposed during the passage of the first contact member through the third fugitive indexed position allows to devote all the kinetic energy again available at the end of the opening stroke at the first contact member linked to the piston, so as to favor the blowing of the arc at the nozzle, which is important for cut off the overload currents, and also makes it possible to replace with fresh gases and clean the heated and dirty gases during the cut-off.

Preferably, the second indexed position P ₅ is located between the fugitive position for separating the first and the second arcing contact P ₃ and the open position. This choice makes it possible to precisely optimize the kinetic energy of the device at the location of the travel of the contacts chosen for the extinction of the arcs linked to the capacitive currents.

Preferably, the maximum value is greater than 1.5. The increase in speed the relative of the arcing contacts is thus even more favored.

Preferably, the second permanent contact member and the second arcing contact member are integral with one another. Admittedly, this solution has the effect of globally increasing the moving mass of the system, compared to a solution where only the second arcing contact would be mobile. However, it appears that this additional mobile mass is not harmful in view of the desired effects. Indeed, the best efficiency of the mechanism is obtained for a speed ratio V ₂ / V ₁ equal to the mass ratio of the moving parts on either side of the transmission mechanism. If the mass M ₂ of the mobile assembly of the second contact member is very low, the ratio M ₁ / M ₂ will be very high, and it will become difficult in practice to produce a transmission mechanism whose structure is simple and which ensures such a maximum transmission ratio, while ensuring low values of the transmission ratio at the start and at the end of the race.

Advantageously, the first contact member and the nozzle together form a first movable piece of mass M ₁ , the second permanent contact member and the second arcing contact piece form a second movable piece of mass M ₂ and when the first member contact passes through the first indexed fugitive position, the gear ratio checks the relationship: 0.8 M 1 M 2 ≤ V 2 V 1 ≤1,2 M 1 M 2 .

It is advantageous for the maximum of the ratio V ₂ / V _{1 to} be as close as possible to the ratio M ₁ to M ₂ , in order to minimize the kinetic energy of the system in the phase of rapid removal of the arcing contacts. Optimally, when the first contact member passes through the first indexed fugitive position, the gear ratio checks the relationship: V 2 V 1 = M 1 M 2 .

• une came pivotant autour d'un axe géométrique fixe par rapport à l'enceinte et comportant une piste curviligne,
• un coulisseau solidaire du deuxième contact d'arc et coopérant avec la piste, et
• un bielle articulée sur la came et sur une pièce solidaire de la tuyère.

According to one embodiment, the transmission mechanism comprises:

• a cam pivoting around a geometric axis fixed relative to the enclosure and comprising a curvilinear track,
• a slide integral with the second arcing contact and cooperating with the track, and
• a connecting rod articulated on the cam and on a part secured to the nozzle.

By appropriately choosing the shape of the curvilinear track, it is possible to obtain very simply the gear ratios sought during the opening race and closing.

• une came pivotant autour d'un axe géométrique fixe par rapport à l'enceinte et comportant une première piste curviligne et une deuxième piste curviligne,
• un premier coulisseau solidaire du deuxième contact d'arc et coopérant avec la première piste, et
• une tringle solidaire de la tuyère et comportant un deuxième coulisseau coopérant avec la deuxième piste.

According to another embodiment, the transmission mechanism comprises;

• a cam pivoting around a geometric axis fixed relative to the enclosure and comprising a first curvilinear track and a second curvilinear track,
• a first slide secured to the second arcing contact and cooperating with the first track, and
• a rod secured to the nozzle and comprising a second slide cooperating with the second track.

This mechanism has the advantage of allowing, if necessary, a straight guide of the rod.

Advantageously, the nozzle has a neck forming a first gas circulation path from the arc expansion volume to an expansion volume inside the enclosure, this first path being closed at least partially by the second contact. arcing as long as the first contact member is between the closed position and a fourth indexed fugitive position P ₆ located between the fugitive separation position of the first and second arcing contacts P ₃ and the open position.

Preferably, the apparatus comprises a second gas circulation path between the expansion volume and the expansion volume of the enclosure, provided with a delay valve which remains closed as long as the first contact member is between the closed position and a fifth indexed position P ₄ , located between the fugitive position for separating the first and second arcing contacts P ₃ and the open position. The two gas circulation paths are in competition, which makes it possible to increase the gas blowing rate. The valve makes it possible to precisely determine the start of the opening of this gas circulation path, after the separation of the arcing contacts. The time interval elapsing between the separation of the arcing contacts and the opening of the valve is used to continue the pressure build-up in the expansion volume caused jointly by the piston and the arc drawn between the arcing contacts at their separation. Advantageously, the fourth indexed position P ₆ is located between the fifth indexed position P ₄ and the open position. In other words, the opening of the second path precedes the opening of the first path during the opening sequence of the mechanism. Preferably, the second indexed position P ₅ is located near the fourth indexed position P ₆ and the fifth indexed position P ₄ .

According to a preferred embodiment, the first arcing contact comprises a tube and the gas circulation path goes through this tube.

BRIEF DESCRIPTION OF THE FIGURES

• la figure 1 représente une vue schématique d'ensemble d'un disjoncteur selon un premier mode de réalisation de l'invention, en position ouverte ;
• la figure 2 représente une partie haute du disjoncteur de la figure 1 en coupe axiale en position ouverte ;
• la figure 3 représente une partie basse du disjoncteur de la figure 1 en coupe axiale en position ouverte ;
• la figure 4 représente une partie haute du disjoncteur de la figure 1 en coupe axiale en position fermée;
• la figure 5 représente une partie basse du disjoncteur de la figure 1 en coupe axiale en position fermée ;
• la figure 6 représente un diagramme où sont portées différentes courbes de vitesse en fonction de la position d'un organe de contact ;
• la figure 7 représente un détail d'un second mode de réalisation de l'invention.

Other advantages and characteristics will emerge more clearly from the description which follows of particular embodiments of the invention, given by way of nonlimiting examples, and represented in the appended drawings in which:

• Figure 1 shows a schematic overview of a circuit breaker according to a first embodiment of the invention, in the open position;
• Figure 2 shows an upper part of the circuit breaker of Figure 1 in axial section in the open position;
• Figure 3 shows a lower part of the circuit breaker of Figure 1 in axial section in the open position;
• Figure 4 shows an upper part of the circuit breaker of Figure 1 in axial section in the closed position;
• Figure 5 shows a lower part of the circuit breaker of Figure 1 in axial section in the closed position;
• FIG. 6 represents a diagram where different speed curves are plotted as a function of the position of a contact member;
• Figure 7 shows a detail of a second embodiment of the invention.

DETAILED DESCRIPTION OF AN EMBODIMENT

Referring to Figures 1 to 5, a high voltage circuit breaker, in this case a circuit breaker intended for voltages exceeding 36kV, immersed in an enclosure 10 filled with a gas with high dielectric strength, for example sulfur hexafluoride SF ₆ and comprising a first contact member 12 driven by an operating mechanism 14, a nozzle 16 integral with the first contact member 12 and a second contact member 18 kinematically connected to the nozzle 16 by means of a transmission mechanism of the movement 20. The enclosure 10 makes it possible to define a geometrical axis of fixed reference 22, which constitutes an axis of translation for the moving parts.

The first contact member 12, visible in detail in Figures 2 and 4, is composed of a cylindrical tubular permanent contact 24 and an arcing contact 26 disposed coaxially with the interior of the permanent contact 24. The arcing contact 26 is also tubular and is provided at its free end with a plug-in clamp 28 composed of contact fingers arranged in a corolla. The permanent contact 24 is itself provided with a range cylindrical plug-in end 30 allowing its cooperation with the second contact member 18. The arcing contact 26 and the permanent contact 24 are integral with one of the other and jointly driven by the operating mechanism 14.

The nozzle 16 is constituted by a piece of insulating material allowing degassing in presence of an electric arc, for example in Teflon. It is fixed on an internal surface of permanent contact 24 and is interposed between the cylindrical racking range end 30 of the permanent contact and the clamp 28 of the arcing contact. The nozzle forms a neck 32 separating two recesses 34, 36.

The end racking range 30 of the permanent contact 24 is extended by a cylindrical outer peripheral surface of a sliding contact wall 38 which slides axially inside a cylindrical collector 40 fixed relative to the enclosure 10 serving as support and guide for the contact member 12, the collector 40 being provided with a sliding contact ring 41 ensuring electrical contact between the permanent contact 24 and the collector 40 during the translation of the permanent contact 24. The cylindrical collector 40 delimits an internal compression volume 42 hermetically closed by a cylinder head 44. The permanent contact 24 is provided, at its axial end penetrating into the collector 40, a piston 46 which separates the compression volume 42 from an arc expansion volume 48 radially delimited by the cylindrical wall 38 of the permanent contact 24 and, at its axial end opposite the piston 46, via the nozzle 16. The piston 46 is provided with a discharge valve 50 opening as soon as the compression volume 42 is in overpressure with respect to the arc expansion volume 48. The piston 46 is integral with the permanent contact 24 and arcing contact 26 and provides a current path between the contact 24 and the arcing contact 26. The arcing contact 26 forms a tube 52 which passes through the piston 46 and cylinder head 44, and protrudes inside a delimited expansion volume 54 by the sealed enclosure 10. The trigger volume 54 occupies all the space available in the enclosure, up to the recess 36. The end of the tube 52 is fixed to a rod 56 constituting the output member of the drive mechanism 14. Lateral openings 58 are formed at the end of the tube 52, so that a circulation path of gas 60 between the arc expansion volume 48 and the expansion volume 54, passing through inside the tube 52. However, a sealing sleeve 61 integral with the cylinder head 44 acting as a delay valve, hermetically covers the openings 58 in the closed position shown in Figure 4.

The cylinder head 44 is provided with a filling valve 62 and a drain valve 64. The filling valve 62 ensures communication from the expansion volume 54 to the volume of compression 42, when the compression volume 42 is in depression by relative to the expansion volume 54. The drain valve 64 ensures the communication of the compression volume 42 towards expansion volume 54, when the pressure difference between the compression volume 42 and the expansion volume 54 is greater than a threshold of emptying determined by a return spring 66 of the valve 64.

The second contact member 18, visible in detail in Figures 3 and 5, consists a second permanent contact 70 and a second arcing contact 72 integral with one of the other. The permanent contact 70 is formed by an openwork tubular metal part, of which a free end is provided with a contact clip 74 in the shape of a corolla. The contact permanent 70 slides axially in a fixed collector 74 provided with a sliding contact 76 ensuring the electrical contact between the permanent contact 70 and the collector 74 during the translation of the permanent contact 74. The second arcing contact 72 forms a finger metallic 78 to the inside diameter of the nozzle neck, extended by a metallic rod 80. The arcing contact 72 and the permanent contact 70 are fixed to each other by via a diametral bar 82 also ensuring the passage of current between the two contacts 70, 72.

The movement transmission mechanism 20 is composed of a pivoting cam of return 84 cooperating with an axial end of the rod 80 of the arcing contact 72 and with a transmission link 86. The cam 84 pivots about a geometric pivot axis fixed 89, perpendicular to the reference axis 22. The link 86 is articulated on the cam 84 and on a crown 88 fitted to an axial end of the nozzle 16. The end axial of the arcing contact 72 is provided with a roller 90 having the function of a slide and cooperating with a track formed by a curvilinear groove 92 in the shape of a bill hook, made in cam 84. An end of stroke return spring 94 recalls bar 82 and the second contact member 18 towards the closed position.

The apparatus operates as follows.

In the closed position, in FIGS. 4 and 5, the clamp 74 of the second permanent contact 70 encloses the outer periphery 30 of the first permanent contact 24 and provides a path for current passing through the first collector 40, the sliding contact 41, the first contact permanent 24, the clamp 74, the second permanent contact 70, the sliding contact 76 and the second collector 76. The finger 78 forming the end of the second arcing contact 72 penetrates deeply into the first arcing contact 26 and plugs the tube 52. The clamp 28 of the first arcing contact 26 grips finger 78 and forms a second current path between the first and second collectors. Finger 78 plugs the end of the tube 52 formed by the arcing contact 26, so that the gas column contained in the tube 52 is closed. The finger 78 also occupies the entire interior space of the neck 32, so that it closes also at this level at least partially the arc expansion volume 48.

When opening the device, the operating mechanism 14 drives the first member contact 12 continuously and without stopping the closed position shown in FIGS. 4 and 5 in the open position shown in FIGS. 1 to 3. The movement of the first member contact 12 is transmitted to the second contact member 18 via the nozzle 16 and the transmission mechanism 20.

In order to describe more precisely the kinematics of the opening, we have shown in the figure 6 the curves representative of the speed of the first contact member 12 (curve A), of the speed of the second contact member 18 (curve B), of the ratio between the speed of the second contact member 12 and the speed of the first contact member 18 (curve C), in function of the displacement of the first contact member 12 relative to the collector 40, plotted on the abscissa.

The shape of the cam 84 is such that at first, the second contact member 18 remains practically stationary, so that all the energy of the drive mechanism 14 serves to accelerate the first contact member 12. other words, if we consider the module V ₁ of the speed of the first contact member 12 and the module V ₂ of the speed of the second contact member 18, the ratio V ₂ / V ₁ is close to zero, and in in all cases less than 0.5, as long as the first contact member is between the closed position and a first indexed fugitive position designated by P ₁ on the diagram. Beyond P ₁ , the first contact member 12 reaches a position P ₂ of separation of the permanent contacts 24, 70, located approximately 10% of its total stroke. The cam 84 has pivoted a few degrees, so that the transmission ratio of the speeds V ₂ / V ₁ increases very quickly to exceed 1. When the first contact member 12 reaches a position P ₃ in which it separates from the second contact arc 72, it covered about 30% of the opening stroke, and the gear ratio exceeds 1.5. The relative speed of separation of the arcing contacts, which is equal to V ₁ + V ₂ , is then very high. The ratio V ₂ / V ₁ remains greater than 1.5 for approximately 0.5 to 3 ms, allowing very rapid separation of the arcing contacts 26, 72, and goes through a maximum when the first contact member reaches a position P ₅ . As long as the speed ratio V ₂ / V ₁ remains greater than 1, preference is given to increasing the speed of the lightest contact member, namely the second contact member 18, which does not support the nozzle 16, with respect to the displacement of the heaviest contact member, namely the first contact member 12. This bias allows, in this phase of separation of arcing contacts, to maximize the relative speed V ₁ + V ₂ of the mobile assembly for a given overall mechanical work provided by the mechanism 14. In fact, if we consider a simplified model of the mechanical system considered, the maximum speed is obtained for: d ( V 1 + V 2 ) dt = 0, that is dV 1 = - dV 2

As a first approximation, the minimum work is obtained for: dW = M 1 V 1 dV 1 + M 2 V 2 dV 2 = 0 where M ₁ is the mass of the moving parts integral with the first contact member 12, that is to say as a first approximation, the sum of the masses of the permanent contact 24, of the arcing contact 26, of the rod 56, of the nozzle 16 and of the crown 88, and where M ₂ is the mass of the moving parts integral with the second contact member 18, namely the permanent contact 70, the arcing contact 72 and the bar 82.

We then obtain: M 1 V 1 - M 2 V 2 = 0 either again V 2 V 1 = M 1 M 2

This simplified model, which does not take into account the moving masses of the movement transmission mechanism, therefore indicates that there is interest, if one wants to maximize the relative speed V ₁ + V ₂ while minimizing the kinetic energy, in ensuring that the speed ratio V ₂ / V ₁ is close to the ratio M ₁ / M ₂ of the moving masses of the moving parts of the first and second contact members. In practice, the mass M ₁ of the first moving part, which also includes the nozzle, is always greater than the mass M ₂ of the second moving part. The M ₁ / M ₂ ratio will often be relatively high, of the order of 1.5 to 2, so that it will be difficult to obtain a V ₂ / V ₁ ratio equal to the mass ratio. We will therefore be satisfied with a V ₂ / V ₁ ratio greater than 1.2 - or better, greater than 1.5 - for a few milliseconds after the separation of the arcing contacts.

The transmission cam 84 is shaped in such a way that when the first contact member has crossed approximately 50% of its opening stroke, the speed ratio V ₂ / V ₁ again becomes less than 1 and rapidly decreases. When the first contact member passes through a fugitive position P ₇ , the gear ratio again becomes less than 0.5, to cancel out at about 90% of the opening stroke.

This purely kinematic description of the opening makes it possible to distinguish different phases.

The initial movement, below P ₁ , allows to allocate all the energy delivered by the drive mechanism 14 to the first contact member 12 and thus quickly initiate a pumping effect. In fact, as soon as the movement of the piston generates an overpressure of the compression volume 42 relative to the arc expansion volume 48, the discharge valve 50 opens and the gas located in the compression volume 42 begins to penetrate in the arc expansion volume 48. The pressure in the arc expansion volume 48 then begins to increase since the contact finger 78 simultaneously closes the flow path 60 through the interior of the tube 52 of the arcing contact and the flow path passing through the neck 32.

When the permanent contacts 24, 70 separate, at P ₂ , the current path passing through the permanent contacts 24, 70 is cut. However, the secondary current path passing through the arcing contacts 26, 72 remains because the finger 78 is still partially inserted in the clamp 28, so that no electric arc is drawn between the permanent contacts 24, 70 before that the position P ₃ of separation of the arcing contacts is not reached. The pressure in the arc expansion volume 48 continues to increase. From position P ₃ , the continuation of the opening essentially depends on the type of current flowing through the circuit breaker at the time of opening. We will successively distinguish the opening on a short-circuit current, the opening on an overload current and the opening on a capacitive current.

When the circuit breaker opens on an alternating short-circuit current, a very energetic electric arc arises between the arcing contacts 26, 72 as soon as they separate and occupies all the space available so that the pressure increases considerably in the volume arc expansion 48. In addition, the electric arc causes degassing of the gasogenic material of the nozzle 16, inducing a further increase in the pressure in the arc expansion volume 48. At the time of separation of the arcing contacts 26, 72, the delay valve 61 still covers the orifices 58, so that the gas is trapped in the arcing expansion volume 48, further promoting the pressure build-up. After a few centimeters of additional travel, the orifices 58 arrive uncovered at point P ₄ of the curve in FIG. 6, and the gas contained in the expansion volume escapes through the interior of the tube 52 of the arcing contact 26 towards the trigger volume 54. As soon as the arcing contact 72 has descended beyond the neck 32, at a point P ₆ of the curve in FIG. 6, the finger 78 which previously blocked the neck, releases a another circulation path for the gas from the arc expansion volume 48 to the expansion volume 54, passing through the neck 32. These exhausts are however insufficient to significantly reduce the pressure in the arc expansion volume 48 by so that the pressure in the arc expansion volume 48 exceeds the pressure in the compression volume 42 and that the discharge valve 50 closes. When the opening movement continues, the piston 46 compresses the gas located in the compression volume 42 until it reaches the emptying threshold, beyond which the emptying valve 64 opens, allowing evacuation to the expansion volume 54 of the gas retained in the compression volume 42, so that the continuation of the opening movement is not hampered. The arc goes out when the current passes through zero. However, the pressure in the arc expansion volume 48 does not decrease quickly enough to allow the discharge valve 50 to open again. In this mode of operation, the arc expansion volume 48 and the compression volume 42 therefore remain separate until the end of the opening. When the first contact member has crossed approximately 50% of its opening travel, the speed ratio V ₂ / V ₁ becomes again less than 1 and rapidly decreases.

When the circuit breaker opens on an alternating overload current, an energetic electric arc arises between the arcing contacts as soon as they separate, in position P ₃ . Due to the high pressure prevailing in the arc expansion volume 48 at the end of the previous phase, the electric arc is subjected to significant constriction. In addition, compressed gas offers a higher heat capacity than uncompressed gas, allowing more efficient blowing of hot gases generated by the electric arc. The electric arc gives off significant energy, which causes degassing of the gas-forming material from the nozzle 16, inducing a further increase in the pressure in the arc expansion volume 48, so that the discharge valve 50 closes. The exhaust of the gas is postponed until the openings 58 open at point P ₄ . The gas contained in the expansion volume escapes through the interior of the arc contact tube to the expansion volume. As soon as the arcing contact has descended beyond the neck, beyond the point P ₆ , the gas also escapes towards the bottom of the nozzle 16. The arc is extinguished when the current flows through zero. If the energy released by the arc was not very large, the pressure in the arc expansion volume 48 decreases rapidly, allowing the discharge valve 50 to reopen. When the first contact member has crossed about 50% of its opening stroke, the speed ratio V ₂ / V ₁ becomes less than 1 and decreases rapidly. In this phase, the available energy of the drive mechanism 14 therefore serves to accelerate again in a privileged manner the first contact member 12 and therefore the movement of the piston 46 in the compression volume 42. Fresh and clean gases are therefore again directed from the compression volume 42 to the arc expansion volume 48 and to the arc contacts 26, 72, until the end of the opening, making it possible to avoid a re-ignition of the arc between arcing contacts.

When the arcing contacts, by separating at P ₃ , open a capacitive circuit crossed by a low current, according to the conditions of a capacitive test, a relatively weak arc is drawn between the arcing contacts 26, 72. This arc dies out almost immediately by itself thanks to the good quality of the dielectric gas. The current is interrupted and the voltage between the contact members 12, 18 begins to increase very quickly. Due to the movement of the piston 46 in the compression volume 42, a continuous flow of fresh gas enters the arc expansion volume 48 where the pressure increases. As soon as the orifices 58 are no longer closed by the sleeve 61 (point P ₄ ), the gases are evacuated through the tube 52 towards the expansion volume 54. To avoid reclacing of the electric arc between the contact members 12, 18, it is essential that the voltage between the contacts 12, 18 remains below the disruptive voltage. However, in the operating range considered, Paschen's law indicates that the disruptive voltage is an increasing function of the product of the gas pressure by the distance separating the contacts. It is therefore essential that when the arc is extinguished, the disruptive voltage is high and increases very quickly, faster in any case than the voltage between the arcing contacts.

This is precisely what the kinematic characteristic described above allows. Indeed, the point P ₅ corresponding to the maximum of the speed ratio V ₂ / V ₁ is located between the point P ₃ of separation of the arcing contacts and the open position. In addition, this point corresponds to a speed ratio greater than 1, which makes it possible to favor the increase in speed of the lightest contact member, namely the second contact member 18, which does not support the nozzle 16 , with respect to the displacement of the heaviest contact member, namely the first contact member 12. This bias makes it possible, as has been shown previously, to maximize the relative speed V ₁ + V ₂ of the mobile assembly for a given overall mechanical work provided by the mechanism 14.

In this phase, we are therefore led to favor the increase in the relative speed of separation V ₁ + V ₂ of the arcing contacts compared to the increase in the speed V ₁ of the piston 46. In other words, if we refer to Paschen's law, we favor the increase in the distance between the contacts compared to the increase in pressure. Note, however, that the movement of the piston 46 inside the compression volume 42 is sufficient to maintain, or even slightly increase, the overpressure of the arc expansion volume 48 relative to the expansion volume 54, despite the continuous flow of gas through the tube 52 of the arcing contact 26 towards the expansion volume 54, since the active surface of the piston 46 is greater than the internal section of the tube 52. But the increase in pressure in the expansion volume is hampered by the flow paths, at the latest when the contact finger 78 escapes from the neck 32 of the nozzle and opens the second gas circulation path passing through the neck 32.

When the first contact member has reached 50% of its opening stroke, the distance between the contacts is sufficient to avoid any reclamping of an arc under the conditions of capacitive testing. The exhaust of gases from the compression volume 42 to the volume Arc 48 expansion continues until the end of the opening.

Beyond point P ₇ and under all opening conditions, fresh and clean gases are directed from the compression volume 42 to the arc expansion volume 48 and to the arc contacts 26, 72, up to 'at the end of the opening, to avoid re-striking the arc between the arcing contacts. Furthermore, the end of the movement of the second contact member is used to compress the spring 94.

The closing takes place in reverse, noting that the filling valve 62 then becomes active to allow filling of the compression volume 42. After the first 10% of the closing stroke, the second contact member 18 begins to move. The spring 94 then makes it possible to avoid any blockage of the transmission mechanism 20.

Naturally, various modifications are possible.

The opening of the orifices 58 by the delay valve 61 (at point P ₄ ) takes place after the separation of the contacts (at point P ₃ of the curve), and preferably before the opening of the throat of the nozzle (at the point P ₆ ) because it is preferable to first open the gas circulation path which has a smaller passage section, in this case path 60. The positioning of points P ₄ and P ₆ relative to point P ₅ determining the maximum the gear ratio is not critical, as long as these three points remain close to each other. According to a first alternative to the diagram in FIG. 6, the point P ₆ can be between P ₄ and P ₅ . According to another alternative, the point P ₄ can be between P ₅ and P ₆ . In some applications, it is possible to do without the delay valve 61, so that the gas circulation path 60 opens as soon as the finger 78 leaves the tube 58 at point P3, knowing that the finger 78 plugs the tube 52 in the closed position.

One can provide a transmission mechanism of different structure, to obtain a speed curve identical to that of the first embodiment. Figure 7 shows a detail of the second embodiment, in which the transmission mechanism 120 comprises a cam 184 cooperating on the one hand with one end of the arcing contact 80 and on the other hand with a rod 186. The end of the arcing contact 80 is provided as in the first embodiment of a roller 190a having a sliding function and cooperating with a track 192a constituted by a curvilinear groove made in the cam 184. From even, the rod 184 is provided at its end with a roller 190b having the function of slide and cooperating with track 192b constituted by a second curvilinear groove in form of buttstock practiced in the cam 184. The shape of the two tracks 192a and 192b is chosen so as to obtain gear ratios of the same type as those described for the first embodiment. The other elements of the circuit breaker according to the second mode of embodiments are identical to those of the first mode.

Furthermore, it is possible to provide a valve closing the tube near the finger of contact in place of the sleeve 61, so as to further promote the increase in pressure in the expansion volume at the start of opening, especially in the capacitive test conditions.

In the embodiments described, the permanent contact 70 is movable and integral with the arcing contact 72. It is also conceivable to provide a fixed permanent contact 70 and an arcing contact 72 alone driven by the transmission mechanism 20.

Claims (15)

High voltage load breaking electrical equipment comprising, inside a sealed enclosure (10) filled with a gas with high dielectric strength and defining a geometric reference axis (22): a fixed support (40) defining a compression volume (42), a first contact member (12) movable relative to the support (40) and comprising: a first permanent contact (24), a nozzle (16) of electrically insulating material, integral with the first permanent contact (24), a piston (46) integral with the first permanent contact (24) and sliding in the support (40), so as to delimit with the nozzle (16) an arc expansion volume (48), and to separate the volume d arc expansion (48) from the compression volume (42), the piston (46) being provided with a discharge valve (50) from the compression volume (42) to the arc expansion volume (48 ), which opens when the compression volume (42) is overpressure relative to the arc expansion volume (48), a first arcing contact (26) integral with the first permanent contact (24) and projecting inside the arcing expansion volume (48); a second contact member (18) having a second permanent contact (70) and a second arcing contact (72) movable relative to the enclosure; a drive mechanism (14) for driving the first contact member (12) from a closed position to an open position with an axial translational movement along the reference axis (22), passing through a position fugitive for separating the first and second permanent contacts (P ₂ ) in which the first and second permanent contacts lose contact with each other, and passing through a fugitive position for separating the first and second arcing contacts (P ₃ ) in which the first and second arcing contacts lose contact with each other, located between the fleeting position of separation of the first and second permanent contacts (P ₂ ) and the open position; a transmission mechanism (20) constituting a permanent kinematic connection between the nozzle (16) and the second arcing contact (72) for transmitting a movement from the nozzle (16) to the second arcing contact (72),
characterized in that the transmission mechanism (20) is such that when the first contact member (12) moves axially in one direction with a speed having a module V ₁ , the second arcing contact moves in translation along l reference axis (22) in opposite direction with a speed having a module V ₂ which is in a ratio V ₂ / V ₁ with the module V ₁ , the ratio V ₂ / V ₁ being variable as a function of the position of the first contact member (12) relative to the enclosure (10) so that: the ratio V ₂ / V ₁ remains below a value of 0.5 as long as the first contact member (12) is between the closed position and a first indexed position (P ₁ ) located between the closed position and the fleeting position separation of the first and second arcing contacts (P ₃ ), the ratio V ₂ / V ₁ passes through a maximum value greater than 1 when the first contact member (12) passes through a second indexed fugitive position (P ₅ ) located between the fugitive position of separation of the first and second permanent contacts (P ₂ ) and the open position, the ratio V ₂ / V ₁ remains below a value of 0.5 as long as the first contact member is between a third indexed position (P ₇ ) located between the second indexed position (P ₅ ) and the open position of on the one hand, and the open position on the other. Electrical load cut-off device according to claim 1, characterized in that the second indexed position (P ₅ ) is located between the transient position for separating the first and second arcing contacts (P3) and the open position. Electrical switchgear under load according to any one of the preceding claims, characterized in that the maximum value is greater than 1.5. Electrical switchgear under load according to any one of the preceding claims, characterized in that the second permanent contact member (70) and the second arcing contact member (72) are integral with one another. Electrical switchgear under load according to claim 4, characterized in that : the first contact member (12) and the nozzle (16) together form a first movable piece of mass M ₁ the second permanent contact member (70) and the second arcing contact member (72) form a second moving mass of mass M ₂ ; when the first contact member (12) passes through the first indexed fugitive position, the gear ratio checks the relationship: 0.8 M 1 M 2 ≤ V 2 V 1 ≤1,2 M 1 M 2 Electrical switchgear under load according to claim 5, characterized in that when the first contact member passes through the first indexed fugitive position, the gear ratio checks the relationship: V 2 V 1 = M 1 M 2 Electrical switchgear under load according to any one of the preceding claims, characterized in that the transmission mechanism (20) comprises: a cam (84) pivoting around a geometric axis (88) fixed relative to the enclosure (10) and comprising a curvilinear track (92), a slide (90) integral with the second arcing contact (72) and cooperating with the track (92), and a connecting rod (86) articulated on the cam (84) and on a part (88) integral with the nozzle (16). Electrical switchgear under load according to any one of Claims 1 to 6, characterized in that the transmission mechanism comprises: a cam (184) pivoting about a fixed geometric axis with respect to the enclosure and comprising a first curvilinear track (192a) and a second curvilinear track (192b), a first slide (190a) integral with the second arcing contact (72) and cooperating with the first track (192a), and a rod secured to the nozzle (16) and comprising a second slide (190b) cooperating with the second track (192b). Electrical switchgear under load according to any one of the preceding claims, characterized in that the nozzle has a neck forming a first gas circulation path from the arc expansion volume (48) to an expansion volume (54 ) inside the enclosure, this first path being closed at least partially by the second arcing contact (72) as long as the first contact member (12) is between the closed position and a fourth fleeting position indexed (P ₆ ) located between the fleeting position of separation of the first and second arcing contacts (P ₃ ) and the open position. Electrical switchgear under load according to claim 9, characterized in that it comprises a second gas circulation path (60) between the expansion volume (48) and the expansion volume (54) of the enclosure ( 10). Electrical switchgear under load according to claim 9, characterized in that the second gas circulation path (60) is provided with a delay valve (61) which remains closed as long as the first contact member (12) is located between the closed position and a fifth indexed position (P ₄ ), located between the transient position for separating the first and second arcing contacts (P ₃ ) and the open position. Electric switchgear under load according to claim 11, characterized in that the fourth indexed position (P ₆ ) is located between the fifth indexed position (P ₄ ) and the open position. Electric switchgear under load according to claim 12, characterized in that the second indexed position (P ₅ ) is located near the fourth indexed position (P ₆ ) and the fifth indexed position (P ₄ ). Electrical switchgear under load according to claim 11, characterized in that the first arcing contact comprises a tube and in that the gas circulation path passes through this tube. Electrical switchgear under load according to claim 14, characterized in that as long as the first contact member is between the closed position and the separation position of the first and second arcing contacts, the second arcing contact closes the tube.

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