EP0536039A1 - Ultra-high voltage circuit breaker - Google Patents

Abstract

The present invention relates to a cut-out chamber for ultra high voltage comprising a main chamber (1) comprising an insulating envelope containing permanent contacts, arcing contacts and two closing resistors inserted by a semi-mobile device called a switching switch putting into operation one of the resistors, said first resistance, before the other, said second resistance. An auxiliary chamber (2) is mounted in parallel with the main chamber (1) and comprises an insulating envelope (20) containing an opening varistor (26) associated with a tripping switch (30) having a delay mechanism of the opening located inside the envelope (20). <IMAGE>

Description

The present invention relates to an ultra high voltage circuit breaker and more specifically to an ultra high voltage breaking chamber comprising a main chamber comprising an insulating envelope containing permanent contacts, arcing contacts and two closing resistors inserted by a device. semi-mobile said interlock switch activating one of the resistors, said first resistance, before the other, said second resistance.

It is known that the operating overvoltages in atmospheric air do not proportionally follow the isolation height. This is why, in ultra high voltage (voltage greater than or equal to 1000 kV, hereinafter called UHT), extremely low operating overvoltages are imposed on the circuit breakers, for example 1.6 pu instead of 3 pu allowed in 245 kV.

The CIGRE review, Electra of January 1989 (n ° 122, pages 43,44) discloses that the UHT circuit breakers will be equipped with closing resistors and opening resistors.

In the French addition certificate No. 2 503 448 deposited on March 31, 1981 by the Applicant, a high voltage compressed gas circuit breaker is described comprising two closing resistors, the insertion devices of which are integral, that of the first resistance comprising a semi-mobile tubular contact cooperating with a contact connected to the second resistor which consists of a stack of annular resistors arranged coaxially and outside the first resistor.

In patent application No. 2,658,949 filed on February 27, 1990 by the Applicant, there is disclosed a high voltage circuit breaker assisted by a varistor arranged in a chamber separate from the breaking chamber, called the auxiliary chamber, and connected in series with a trip switch comprising a movable contact made in the form of a metal rod fixed to a metal hose connecting the two chambers by means of an opening retarder located outside of them and actuated by the rod of the breaking chamber.

The present invention proposes to combine, inter alia, these two known techniques for producing a UHT circuit breaker meeting the overvoltage requirements and moreover having a compact constitution.

To do this, an auxiliary chamber is mounted in parallel with the main chamber and includes an insulating envelope containing an opening varistor associated with a trip switch having an opening delay mechanism located inside the envelope of the auxiliary chamber.

The use of a varistor instead of a resistor makes it possible to more effectively reduce overvoltages and to avoid having a blowing by compression on the trip switch. Indeed, thanks to its variable resistance with a large coefficient of non-linearity such as zinc oxide, the varistor adapts better with the circuit to reduce the overvoltage. The residual current is cut off automatically without blowing when the voltage decreases to zero.

The arrangement of the delay mechanism inside the envelope of the auxiliary chamber makes it possible to protect it from external effects such as rain, wind or hail.

According to a preferred embodiment, the switch is actuated by a metal hose directly connected to the operating rod of the main chamber.

Thus, a single control device for the main chamber and the particularly simple and reliable auxiliary chamber is produced.

Advantageously, the mechanism for delaying the opening of the trip switch is inertial.

In this way, no separate specific delay device is to be mounted on the chambers.

Preferably, the varistor consists of a stack of varistors in the form of cylindrical pellets placed in an insulating tube.

According to a specific construction method, this switch comprises a fixed metal support tube in which is slidably mounted longitudinally another metal tube electrically connected to the support tube and connected by its lower end to the end of the hose, the upper end of the tube being closed. by an insulating washer and crossed by a metal rod electrically connected to the tube and the upper part of which supports a contact sleeve cooperating with contact fingers mounted at the lower end of the varistor, the lower part of the rod being provided with a conical stop intended to cooperate with an internal shoulder of conical shape complementary to the tube, a spring being disposed inside the tube and around the rod between the upper end of the tube and the lower end of the rod, the spring being relaxed when the switch is in the rest position on or off brood.

Preferably, the stop integral with the lower part of the rod is made of polytetrafluoroethylene

The invention also relates to a circuit breaker for ultra high voltage, multi-break at SF6, comprising cut-off chambers, main and auxiliary, connected in series, arranged vertically in a candlestick and equipped with distribution capacitors, with a main cut-off chamber per support column. , whose interrupting chambers are as described above.

The invention is set out below in more detail with the aid of drawings representing only one embodiment.

• Figure 1 is a front view in partial section of a breaking chamber according to the invention.
• Figure 2 is a detail sectional view of the insertion device of the auxiliary chamber.
• FIG. 3 represents a phase of a UHT circuit breaker equipped with such breaking chambers.

In FIG. 1, the main switching chamber 1, the auxiliary chamber 2 and partially the support column 3 are shown.

The main chamber 1 is of the type of the interrupting chamber described in the certificate of addition no. 2 503 448. It comprises an insulating envelope, for example made of ceramic, which comprises at its upper end a plate 5 connected to a first outlet current. The envelope is surmounted by a cover 10 housing the two closing resistors, the first of which is formed by a stack of cylindrical resistive pellets, based on carbon for example, and the second of a stack of annular resistors arranged coaxially and outside the first. A semi-mobile insertion device, called an interlock switch, has a tubular insertion contact of the first resistor at its lower end and a tubular insertion contact of the second resistor at its upper part. A second outlet is connected to the lower plate 5A.

In parallel to this main chamber 1, an auxiliary chamber 2 is mounted, the plates 5 and 5A of the main chamber 1 being connected respectively by the conductor 23 and by the conductive support plate 24 to the plates 21 and 22 of the auxiliary chamber 2 This chamber 2 comprises an insulating envelope, for example of porcelain, in which is housed an opening varistor 26 associated with a tripping switch 30, shown diagrammatically in FIG. 1. A cover 11 extends the envelope 20 in order to allow the housing of the varistor 26 which consists of a stack of varistors in the form of cylindrical pellets, based on zinc oxide, disposed in an insulating tube, in a manner known per se.

The switch 30 is actuated by a mechanism directly connected to the operating rod 121 of the main chamber 1. The latter is housed in an insulating column 120 supporting the main chamber 1. The rod 121 is extended by a metal portion 122 connected to the conventional conventional moving equipment of the main chamber 1. It is also connected to a metal hose 123 fixed to the trip switch 30 and this hose 123 is placed in a rigid metal sheath 124.

Rings 200 and 201 are arranged below and above the chambers 1 and 2, in order to reduce the visual emanations (Corona effect) and to improve the dielectric strength of the breaking chamber and the support insulator.

Preferably, carbon-based resistive pads are mounted in series with the varistor discs 26 to limit the residual current to a certain value, in the event of a cut in high restored voltage.

FIG. 2 shows precisely the trip switch 30 of the auxiliary chamber 2.

This switch is mounted on the lower plate 22 of the auxiliary chamber 2 through which the hose 123 passes through its sheath 124. More precisely, a metal support tube 31 is fixed on the plate 22 in which another metal tube 32 is slidably mounted. having at its lower end an insulating diametrical bar to which the end of the hose 123 is fixed by means of a washer. An electrical sliding contact connects the two tubes 31 and 32.

The upper end of the tube 32 is closed by an insulating washer 35. Inside the tube 32, is arranged a rod 37, for example of high resistance brass, which by its upper part passes through the washer 35 and supports a sleeve contact 43, preferably screwed and copper.

The lower part of the rod 37 has a diameter greater than that of the central part of the rod 37 and has a threaded bore 37B drilled at its lower end. Near the lower end of part 37A, a shoulder 37C serves as a support for a ring 38, with a conical external profile, preferably made of polytetrafluoroethylene, and provided with an O-ring 39. The conical ring 38 is held in place by the head of a bolt 40, screwed into the bore 37B with interposition of seals 41 and 42. The head of the bolt 40 is electrically connected to the tube 32 by at least one contact finger 43. A metal spring 34 is disposed between the shoulder 37C and the washer 35.

The tube 32 has a conical inner shoulder intended to receive the conical ring 38 in abutment.

At the lower end of the stack of varistors 26 housed in the insulating tube 27 is mounted a metal closure part 52 retaining the varistors 26 and provided with a tube 50 terminated by contact fingers 51 intended to cooperate with the sleeve 43 .

• - en position fermée (figure 2), le manchon de contact 43 est en contact avec les doigts 51, la varistance est insérée et le ressort 34 est détendu;
• - à l'ouverture de l'interrupteur 30, le tube 32 est tiré vers le bas par le flexible 123, comprimant le ressort 34; en raison de leur inertie, la tige 37 et le manchon 43 restent immobiles, de sorte que la varistance reste insérée grâce à cet agencement que l'on peut qualifier de retardateur; lorsque le ressort 34 arrive en fin de compression, la tige 37 est entraînée vers le bas sans à-coup grâce à l'épaulement conique du tube 32 coopérant avec la bague conique 38 et sa bague torique 39; le manchon 43 et les doigts 51 se séparent et la varistance 26 est dé- sinsérée.

The operation of this trip switch is as follows:

• - In the closed position (Figure 2), the contact sleeve 43 is in contact with the fingers 51, the varistor is inserted and the spring 34 is relaxed;
• - At the opening of the switch 30, the tube 32 is pulled down by the hose 123, compressing the spring 34; due to their inertia, the rod 37 and the sleeve 43 remain stationary, so that the varistor remains inserted by virtue of this arrangement which can be described as retarder; when the spring 34 arrives at the end of compression, the rod 37 is driven smoothly downward thanks to the conical shoulder of the tube 32 cooperating with the conical ring 38 and its O-ring 39; the sleeve 43 and the fingers 51 separate and the varistor 26 is removed.

The setting of the insertion and deactivation time of the varistor 26 is done by the dimension ment of the switch 30. In particular, a parameter is determining, namely the length of the rod 37 under the sleeve 43 projecting from the washer 35, when the spring 34 is at the end of compression, and corresponding to the length of the displacement of the tube 32 before driving the rod 37 at the opening.

FIG. 3 is a schematic view of a phase of a UHT multi-breaker circuit breaker with SF6, more precisely of 1150 kV comprising four chambers. For a voltage of 1500kV, it would include five chambers in series. The arrangement is vertical in a candlestick with one chamber per support column, which facilitates the mechanical strength of the chambers.

The chambers are as described above, with their main chamber 1 containing the arrangement of closing resistors 6, the cut-off contacts 7 and the insertion switch 8 of the resistors 6, called the switching switch, and their auxiliary chamber 2 containing the opening varistor 26 and the trip switch 30 with delay mechanism. At the terminals of these chambers, distribution capacitors 4 are conventionally mounted.

• - à la fermeture,
• l'interrupteur d'enclenchement 8 est fermé en premier lieu et insère la première résistance de fermeture dans le circuit environ 10ms avant l'entrée en contact des contacts d'arc de la chambre principale; environ 5ms avant l'entrée en contact des ces contacts d'arc, on insère la seconde résistance de fermeture et en même temps l'interrupteur de déclenchement 30 se referme mettant la varistance 26 dans le circuit; la fermeture des contacts d'arc court- circuite ensuite à la fois les résistances de fermeture 6 et la varistance d'ouverture 26.
• - à l'ouverture,
• grâce au mécanisme retardateur de l'interrupteur 8, les résistances de fermeture 6 ne sont pas insérées dans le circuit à la séparation des contacts d'arc; les contacts permanents se séparent en premier lieu puis c'est le tour des contacts d'arc; environ 10ms après la séparation des contacts d'arc de la chambre principale 1, les contacts de l'interrupteur de déclenchement 30 se séparent pour couper le courant résiduel traversant la varistance 26.

The operation of such a circuit breaker is as follows:

• - at closing,
• the interlock switch 8 is closed first and inserts the first closing resistor in the circuit approximately 10 ms before the arcing contacts of the main chamber come into contact; approximately 5 ms before these arcing contacts come into contact, the second closing resistance is inserted and at the same time the trip switch 30 closes putting the varistor 26 in the circuit; the closing of the arcing contacts then short-circuits both the closing resistors 6 and the opening varistor 26.
• - at the opening,
• thanks to the delay mechanism of the switch 8, the closing resistors 6 are not inserted in the circuit at the separation of the arcing contacts; the permanent contacts separate first, then it is the turn of the arcing contacts; approximately 10 ms after the separation of the arcing contacts of the main chamber 1, the contacts of the tripping switch 30 separate to cut the residual current passing through the varistor 26.

Claims (7)

1) Cut-off chamber for ultra high voltage comprising a main chamber (1) comprising an insulating envelope containing permanent contacts, arcing contacts and two closing resistors (6) inserted by a semi-mobile device called an interlock switch (8) putting one of the resistances, called the first resistance into operation, before the other, called the second resistance, breaking chamber characterized in that an auxiliary chamber (2) is mounted in parallel with the main chamber (1) and comprises an insulating envelope (20) containing an opening varistor (26) associated with a trip switch (30) having an opening delay mechanism located inside the envelope (20) of the chamber auxiliary. 2) Cut-off chamber according to claim 1, characterized in that the switch (30) is actuated by a metal hose (123) directly connected to the operating rod (121) of the main chamber (1). 3) Cut-off chamber according to claim 1 or 2, characterized in that the mechanism for delaying the opening of the trip switch (30) is inertial. 4) Cut-off chamber according to any one of the preceding claims, characterized in that the varistor (26) consists of a stack of varistors in the form of cylindrical pellets disposed in an insulating tube (27). 5) Cutoff chamber according to any one of the preceding claims, characterized in that this switch (30) comprises a fixed metal support tube (31) in which is slidably mounted longitudinally another metal tube (32) electrically connected to the support tube (31) and connected by its lower end to the end of the hose (123), the upper end of the tube (32) being closed by an insulating washer (35) and traversed by a metal rod (37) electrically connected to the tube (32) and the upper part of which supports a contact sleeve (43) cooperating with contact fingers (51) mounted at the lower end of the varistor (26), the lower part of the rod (37) being provided with 'a conical stop (38) intended to cooperate with an internal shoulder of conical shape complementary to the tube (32), a spring (34) being disposed inside the tube (32) and around the rod (37) between the end upper part of the tube (32) and the lower end of the rod (37), the spring (34) being relaxed when the switch (30) is in the rest position engaged or tripped. 6) Cutting chamber according to claim 5, characterized in that the stop (38) integral with the lower part of the rod (37) is made of polytetrafluoroethylene 7) Circuit breaker for ultra high voltage, multi-break at SF6, comprising breaking chambers, main and auxiliary, connected in series, arranged vertically in a candle and equipped with distribution capacitors, with a main breaking chamber per support column, characterized in that that the interrupting chambers conform to any one of the preceding claims.

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