EP0807946A1 - High-voltage gas-blast puffer type circuit-breaker - Google Patents

Abstract

The circuit-breaker has an envelope (1) preferably of porcelain filled with e.g. sulphur hexafluoride gas under pressure of several atmospheres. One arc contact (10) is part of the moving contact assembly integral with an inner tubular slider (6). The coaxial outer tube (8) carries the moving contact (11) surrounding a blowout (quenching) chamber (13) closed by a nozzle (12). A compression chamber (15) on the other side of a ring (9) is closed by an annular piston (14) sliding freely between a fixed stop (21) and one end of a helical spring (19). A ring (25) floats between a fixed washer (26) and a back-stop (28).

Description

The present invention relates to a self-blowing circuit breaker comprising a casing filled with a dielectric gas under pressure, two arcing contacts cooperating with each other, one forming part of a movable contact assembly secured to an operating member. and adapted to be moved axially in the envelope between a closed position and an open position, the movable contact assembly comprising a first tube carrying at its end the movable arcing contact and a second tube coaxial with the first tube , carrying at the end a movable permanent contact and delimiting, on either side of a crown connecting the first tube and the second tube, a blowing chamber closed by a blowing nozzle and a compression chamber communicating with the blown and closed by a piston.

Patent application 2,696,274 describes such a circuit breaker.

According to this prior document, the piston is semi-mobile and means are provided for immobilizing the piston during a first part of the movement of the mobile contact assembly when the circuit breaker opens and means for, on the contrary, cause axially this same piston during a second part of the movement of this assembly.

The means for axially driving the movable contact assembly during this second part of the movement is constituted by a drive member integral with the movable contact assembly which drives a stop integral with the piston. This stop is arranged on the path of the drive member. Furthermore, during the first part of the movement, the piston is held in a fixed position by a spring placed between the piston and the drive member and pushing the piston which is retained by a crown abutting against a fixed member. , the crown being secured to a tube itself secured to the piston. During this first part of the movement, the drive member slides in a lumen of the tube connecting the piston to the crown until it reaches the stop at the end of the light, then then driving the piston in the second part of the movement.

In such an arrangement, the spring urging the semi-mobile piston causes a permanent force on the control rod and causes an increase in the operating energy required.

The document EP 0 126 929 describes a compressed gas switch having a slightly different structure in the sense that there is no second tube but an annular piston 12, linked to a tube 8, carrying a nominal current contact 5 and sliding directly in an external cylindrical housing 14.

However, this document describes the use of a sliding free piston 15 between a stop 16 linked to the housing 14 and a thrust spring 17.

This arrangement ensures the automatic recoil of the free piston under the effect of the increase in pressure in the compression chamber at the time of the opening operation and thereby limits the pressure increase, it thus brings the advantages of the semi-mobile piston of the first document cited in the introduction but without the control rod being subjected to an additional force.

When the arcing contacts are separated and the blowing gas has escaped, the pressure decreases and the free piston then returns to its position against said fixed front stop under the thrust of the thrust spring.

Unfortunately, with such a free piston, this return occurs with significant kinetic energy producing a shock on the fixed front stop and the attachment parts of this stop being able to cause ruptures.

The object of the invention is therefore to propose a circuit breaker having a structure as defined in the introduction, incorporating a free piston with its advantages but which overcomes the drawback mentioned above.

The subject of the invention is therefore a self-blowing circuit breaker comprising a casing filled with a dielectric gas under pressure, two arcing contacts cooperating with each other, one forming part of a movable contact assembly secured to a operating member and adapted to be moved axially in the envelope between a closed position and an open position, the movable contact assembly comprising a first tube carrying at its end the movable arcing contact and a second coaxial tube to the first tube, carrying at the end a movable permanent contact delimiting, on either side of a ring connecting the first tube and the second tube, a blowing chamber closed by a blowing nozzle and a compression chamber communicating with the blowing chamber and closed by a piston, characterized in that said annular piston located between the two said tubes is mounted to slide freely between a fixed front stop and a spring of p pushed, one end of which bears on the piston and the other end of which is in fixed support, this fixed support 18 being situated on the other side of said front stop fixed relative to said arcing contacts, said piston comprising on the side opposite the support of the thrust spring, an annular recess in which is housed, in the support position of the piston against said front stop, a ring, said ring being mounted floating between a fixed washer integral with said front stop and a rear retaining member and being pierced with at least one orifice, closed by said fixed washer when it is in front stop position forming a non-return valve allowing the introduction of gas into said recess when the piston recedes under the pressure of the gas in said compression chamber when the circuit breaker opens, the movement before the piston returns under the thrust of said thrust spring being damped by the mattress of gas compressed by said ring penetrating said recess.

Other characteristics of the present invention will emerge from the description of an example of implementation of the invention made below with reference to the appended drawing in which:

FIGS. 1 to 6 partially represent a circuit breaker according to the invention in its different positions during an opening operation, from the closed state in FIG. 1 to the complete opening in FIG. 6.

Figure 7 is an enlarged view of a detail of the preceding figures showing the piston with its recess and the ring, allowing damping when the piston returns.

In what follows, there is described by way of example a circuit breaker comprising for each phase an insulating envelope. Of course, the invention also applies to circuit breakers with a metal shell to the ground comprising a separate envelope for each phase or a single envelope for the three phases.

Referring to FIG. 1, the reference 1 designates an insulating envelope, preferably made of porcelain, delimiting an expansion chamber 2 filled with a gas with good dielectric properties, for example sulfur hexafluoride under a pressure of a few bars.

The circuit breaker includes a fixed assembly and a movable contact assembly.

The fixed assembly comprises an arcing contact 3 and a fixed permanent contact constituted by a circular series of fingers 4. These fixed arcing 3 and permanent contact 4 are linked to a first socket outlet 5.

The movable contact assembly comprises an insulating operating part 6 passing through the chamber 2 and connected, at one of its ends, to a mechanism not shown. Its other end is linked to a metal assembly of movable contacts comprising two coaxial tubes 7 and 8. These two tubes 7 and 8 are interconnected by a metal ring 9. The inner tube 7 carries the movable arcing contact 10 and the outer tube 8 carries the movable permanent contact 11 which cooperates, in the closed position of the circuit breaker as shown in the figure 1, by its external periphery with the fingers 4 of the fixed permanent contact. To the permanent movable tubular contact 11 is linked a blowing nozzle 12 made of insulating material.

The space between the permanent movable contact 11, the movable arcing contact 10, the crown 9 and the blowing nozzle 12 constitutes a blowing chamber 13. Furthermore, the tubes 7 and 8, an annular piston 14 located between the two tubes, and the metal crown 9 delimit a compression chamber 15. This compression chamber 15 is separated from the blowing chamber 13 by the metal crown 9 equipped with one-way valves 16 allowing the passage of gas from the compression chamber 15 to the blowing chamber 13.

Fingers 17 of permanent contact, linked to a bottom plate 18 connected to a second socket not shown, are in sliding electrical contact with the external tube 8.

The annular piston 14 is mounted to slide freely between a fixed front stop and a thrust spring 19, one end of which bears on the piston and the other against the fixed bottom plate 18.

The annular piston 14 also slides along three fixed tie rods 20 (only one is visible in the figures), the head 21 of which serves as a fixed front stop for the piston 14. The fixed tie rods 20 are fixed to a fixed sleeve 22 linked to the bottom plate 18. This sleeve 22 guides the spring 19.

Referring now to Figure 7 we will describe in more detail the piston 14 and the means used to provide damping of the shock caused by the return to the front of the piston under the action of the spring 19 at the end of the opening of the circuit breaker when the pressure in the compression chamber 15 has dropped.

The piston 14 is equipped with a valve 23 allowing the passage of gas from the expansion chamber 2 to the compression chamber 15 and not in the opposite direction. It further comprises an annular recess 24 clearly visible in FIGS. 3, 4 and 5. In the breaker rest position, when it is closed or fully open, as shown in FIG. 1, 6 and in the position shown of the piston with respect to at the tie rods 20 in FIG. 7, a floating ring 25 is housed at the bottom of this recess 24, pushed by the piston against a fixed washer 26, itself bearing against the head 21 of the tie rods 20.

The floating ring 25 is pierced with three holes at 120 ° for the passage of the tie rods and also of holes 27 interposed between the passage holes of the tie rods 20. The floating ring 25 is mounted between the fixed washer 26 and a rear retaining member 28 constituting a collar of a barrel 29. This barrel 29 is immobilized axially on the tie rod 20 by a shoulder 30 of the tie rod and by the head 21 of the tie rod 20. The head 21 is actually a screw head tightening the fixed washer 26 and the barrel 29 against the shoulder 30 of the tie rod 20.

To allow the floating ring 25 to move axially between the washer 26 and the flange 28 of the barrel 29, it has a recess 31 around each tie rod 20 which passes through it. This recess being located on the side of the flange 28.

In the position shown in FIGS. 1, 5, 6 and 7, the three orifices 27 are closed by the washer 26.

On the other hand, when the piston 14 recedes (FIG. 2), when the pressure chamber 15 increases in pressure due to the movement to the right of the moving element 6 to 11, the floating ring comes to bear against the flange 28 freeing the orifices 27 and allowing the introduction of the gas into the recess 24 (FIG. 3) while the piston 14 continues to retreat.

In Figure 4, we are in the complete recoil position of the piston.

In FIG. 5, the circuit breaker is open, the gas has escaped in the expansion chamber 2 and the pressure has suddenly dropped in the compression chamber 15, the piston, under the effect of the spring 19 suddenly returns forward but as soon as the floating ring 25 enters the recess 24, it is pushed back against the fixed washer 26 closing the orifices 27 and the gas mattress contained in the recess 24 strongly dampens the end of the return movement of the piston against the ring 25 , pressing against the washer 26 and the latter against the heads 21 of the tie rods 20 (FIG. 6).

Claims (2)

Self-blowing circuit breaker comprising a casing (1) filled with a dielectric gas under pressure, two arcing contacts (3, 10) cooperating with each other, one (10) being part of a fixed movable contact assembly an operating member (6) and adapted to be moved axially in the envelope between a closed position and an open position, the movable contact assembly comprising a first tube (7) carrying at its end the contact of movable arc (10) and a second tube (8) coaxial with the first tube, carrying at the end a movable permanent contact (11) and delimiting, on either side of a ring (9) connecting the first tube ( 7) and the second tube (8), a blowing chamber (13) closed by a blowing nozzle (12) and a compression chamber (15) communicating with the blowing chamber (13) and closed by a piston (14 ), characterized in that said piston (14), annular and located between the two said tubes (7, 8), is slidably mounted free between a fixed front stop (21) and a thrust spring (19) one end of which is supported on the piston (14) and the other end of which is in fixed support, this fixed support (18) being located from l 'other side of said fixed front stop (21) relative to said arcing contacts (3, 10) said piston comprising on the side opposite to the support of the thrust spring (19), an annular recess (24) in which is housed, in the position of support of the piston against said front stop, a ring (25), said ring being mounted floating between a fixed washer (26) integral with said front stop (21) and a rear retaining member (28) and being pierced with at least one orifice (27), closed by said fixed washer (26) when it is in the front stop position forming a non-return valve allowing gas to be introduced into said recess (24) during recoil of the piston under gas pressure in said compression chamber (15) when the circuit breaker opens, the mo uvement before return of the piston under the thrust of said thrust spring (19) being damped by the mattress of gas compressed by said ring (25) penetrating into said recess. Circuit breaker according to claim 1, characterized in that said piston (14) is slidably mounted on fixed tie rods (20), linked to said fixed support (18) of the thrust spring (19), and whose head (21) serves as fixed front stop for said piston (14), and in that said rear retaining member (28) of said floating ring (25) is located on each tie rod (20).

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