EP0508160B1 - Gas blast circuit breaker - Google Patents

Abstract

In a gas-blast circuit breaker, compressed gas is passed through the moving contact piece (28) into the arcing space (40). Said arcing space (40) is bounded by the cylinder (58) and the piston (60) which is moved with the moving contact piece (28). The piston (60) has inlet openings (70) which are closed by means of the valve body (72), such that they can be opened. The operating device (76) is supported on the neck (64) of the piston (60) so that said operating device (76) can be displaced in a reciprocating manner between two latching positions. During switching on, the tab (84) of the operating device (76) strikes against the stop surface (98), as a result of which the operating device (76) is moved into the first latching position (76'). At the same time, the valve body (72) is moved into the closed position (72'). Towards the end of the switching-off movement, the shaft (86) runs onto a stop (96) so that the operating device (76) is moved back into the upper second latching position, as a result of which the valve body (72) is moved into the open position and is held. During switching on, the arcing space (40) is thus connected to the surrounding space (94), and is separated from it again before the start of switching off. The drive is supported when switching off large currents and no more work is demanded of it during switching on and when switching off small currents. The gas-blast circuit breaker thus manages with a low power drive. <IMAGE>

Description

The present invention relates to a gas pressure switch according to the preamble of claim 1.

A gas pressure switch of this type is known from EP-A-0 380 907. When large flows are switched off, the extinguishing gas flowing into a blow-out space supports the drive. In order to avoid an overpressure requiring activation of the drive when switching on, slide-like valve means are provided which, when switched on, release openings in the cylinder delimiting the exhaust chamber, which run in the radial direction in relation to the pressure in the pump chamber, due to the relatively large excess pressure in the blow-out chamber, in order to equalize the pressure between the blow-out space and the surrounding space. In order to control the valve means, a control piston is provided in the pump piston separating the pump chamber from the blow-out chamber. So that the drive does not have to do more work when switching off small flows than with a switch without a blow-out chamber, a piston that delimits it and is moved with the movable contact piece is provided with a large-area check valve that remains open with respect to the surrounding space when a negative pressure occurs in the blow-out chamber. The disadvantage of this known switch is that to open the slide-like valve means, a certain pressure difference must be built up between the pump chamber and the blow-out chamber, which requires drive energy, and that at the beginning of a switch-off stroke, the slide-like valve means must first be brought back into their closed position, the pump chamber enlarged by the displacement of the control piston becomes. This has the consequence that the pressure built up in the pump chamber is reduced, which affects the breaking capacity of the switch. In addition, such slide-like valve means require a complicated structure of the pressure gas switch.

It is therefore an object of the present invention to develop a generic switch in such a way that it has improved switching properties with a simple structure and the drive does not have to do more work when the switch is switched on than in the case of a switch without a blow-out space.

This object is achieved by a generic pressure gas switch which has the features of the characterizing part of claim 1. The valve means are controlled depending on the stroke of the movable contact piece, which prevents an influence on the pump chamber and the build-up of pressure for actuating the valve means.

Particularly preferred and extremely simple design forms of the pressure gas switch according to the invention are specified in claims 2 and 3.

The also particularly preferred embodiments according to claims 4 and 6 ensure that the drive does not have to do more work when switching off small currents than in the case of compressed gas switches without a blow-out space, in which negative pressure in the blow-out space with respect to the surrounding space is prevented. The form of training according to claim 4 is particularly preferred because of its simplicity.

Further preferred forms of training of the invention Gas pressure switches are specified in the remaining dependent claims.

Fig. 1 und 2

in einem Längsschnitt teilweise eine erste Ausbildungsform eines erfindungsgemässen Druckgasschalters in Einschalt- bzw. Ausschaltstellung;

Fig. 3 und 4

in vergrösserter Darstellung die in den Figuren 1 und 2 mit den Pfeilen III bzw. IV bezeichneten Bereiche des Druckgasschalters und

Fig. 5 und 6

in gleicher Darstellung wie Figuren 3 und 4 einen Teil einer zweiten Ausbildungsform des erfindungsgemässen Druckgasschalters.

The present invention will now be described with reference to two training forms shown in the drawing. It shows purely schematically:

1 and 2

in a longitudinal section, partly a first embodiment of a compressed gas switch according to the invention in the on or off position;

3 and 4

in an enlarged view the areas of the pressure gas switch and shown in FIGS. 1 and 2 with the arrows III and IV

5 and 6

in the same representation as FIGS. 3 and 4, part of a second embodiment of the compressed gas switch according to the invention.

A fixed contact piece 10, which is connected in parallel to a continuous current contact piece 12 which also coaxially surrounds this, is connected in a generally known manner to the one port 14 of the compressed gas switch, which is only indicated schematically in FIG. In the switched-on position (FIG. 1), this fixed contact piece 10 closes a blowing nozzle 16 made of insulating material, which is fixedly mounted on the bottom 18 of a metallic pump cylinder 20 that is open at the bottom, and whose inlet 22 via flow passages 24 in the bottom 18 with a pump chamber enclosed by the pump cylinder 20 26 communicates. The pump cylinder 20 has a metal cylinder jacket 20 'on which the bottom 18 is fixed in the upper end region. The bottom 18 and thus the pump cylinder 20 are firmly anchored to a movable contact piece 28. Above the base 18, the movable contact piece 28 has a tulip-like consumable contact piece 30 which cooperates with the fixed contact piece 10 and which, in the switched-on position, delimits the inlet 22 of the blow nozzle 16 on the inside, viewed in the radial direction. Furthermore, the movable contact piece 28 has a blow-out pipe 32, which extends away from the bottom 18 in the direction towards the bottom and which is closed at its lower end by a pin 34 tapered towards the inside of the blow-out pipe 32. The erosion contact piece 30 and the blow-out pipe 32 thus enclose a passage 36, which extends from the upper free end of the movable contact piece 28 and runs in the axial direction and penetrates the bottom 18, the length of which is limited by the pin 34 and which is restricted by radial openings 38 in the blow-out pipe 32 in a blow-out space 40 opens.

On the side facing away from the bottom 18, the pump chamber 26 is delimited by a stationary, ring-like pump piston 42, which surrounds the blow-out pipe 32 above the openings 38. The pump piston 42 has a circumferential groove in which a piston ring 44 made of plastic is arranged, on which the cylinder jacket 20 'is slidably mounted. The pump piston 42 rests on a support tube 46 which surrounds the blow-out tube 32 at a distance and which is supported at the bottom by an intermediate base 48 of an essentially cylindrical second continuous current contact piece 50. A connecting flange 52 protrudes from the second continuous current contact piece 50 to the outside Ensure electrical connection to the other connection of the pressure gas switch, not shown in the figures.

The pump chamber 26 and the blow-out chamber 40 are connected to one another via suction passages 54 in the pump piston 42, which are releasably closed by an annular check valve body 56 which interacts with the pump piston 42. The check valve body 56 forms, together with the pump piston 42, a flap or check valve which opens when the overpressure in the blow-out chamber 40 is higher than the pressure in the pump chamber 26.

The area of the second continuous current contact piece 50 below the intermediate base 48 forms a cylinder 58 in which a piston 60 is slidably supported. The piston 60 has a circumferential groove in which a piston ring 44 'engages to seal between the cylinder 58 and the piston 60. In the bottom of the cylinder 58 forming intermediate floor 48, an axially extending connection opening 62 is provided, the clear width of which is aligned with the clear width of the support tube 46 and thus the subspace 46 'delimited by the support tube 46 and on the top by the pumping piston 42' with the cylinder 58 and piston 60 limited subspace 58 'connects. The blow-out space 40 is thus composed of these two sub-spaces 46 'and 58'.

On the piston 60, a neck 64 protruding toward the top is integrally formed, into which the blow-out pipe 32 is screwed with its lower end region. On the side facing away from the neck 64, a connecting lug 66 protrudes from the piston 60, on which an actuating rod connected to a drive 67 only indicated schematically in FIG. 1 68 is articulated from insulating material.

Large-area inlet openings 70 are provided in the piston 60 (see also FIGS. 3 and 4), which can be closed by means of a disk-shaped valve body 72 which engages around the neck 64 with play and cooperates with the piston 60. Control means 74 leave the valve body 72 in its closed position 72 'on the piston 60, on its side facing the blow-out space 40 in order to close the inlet openings 70 (FIGS. 1 and 3) or hold the valve body 72 in the open position 72˝, as shown in the figures 2 and 4 show. An annular actuating member 76 of the control means 74 engages around the neck 64 of the piston 60 and is guided on the latter in an axially displaceable manner. A locking device 78 defines a lower first locking position 76 '(Figures 1 and 3) and an upper second locking position 76˝ (Figures 2 and 4) for the actuating member 76. For this purpose, the actuating member 76 in the axial direction by the distance between the first and the second locking position 76 ', 76˝ spaced, circumferential locking grooves 80, 80', which cooperate with in the neck 64 of the piston 60 in the radial direction and in the direction biased towards the outside locking balls 82.

Lugs 84 protrude from the actuator 76 in the radial direction toward the outside, only one of which is shown in FIGS. 1 to 4. On each nose 84 is an axially extending, graduated in diameter shaft 86 is attached, which engages with its adjacent to the nose 84, smaller diameter shaft portion 86 'the valve body 72 and with its larger diameter shaft portion 86˝ the piston 60 . The gradation in the shaft 86 forms a drag connection between the valve body 72 and the actuating member 76. If the actuating member 76 is in its first detent position 76 '(FIGS. 1 and 3), the valve body 72 closes the inlet openings 70. The distance between the lower edge of the nose 84 and the valve body 72 located in the closed position 72 'can act as a flap or pressure relief valve. However, the actuating member 76 is in its second locking position 76stellung (FIGS. 2 and 4), the towing connection through the step in the shaft 86 between the first and second shaft parts 86 ′, 86˝ ensures that the valve body 72 is always in the open position 72˝ is held.

With its lower end, the second continuous current contact piece 50 is fastened to an annular holding flange 90 which surrounds the actuating rod 68 at a distance and is supported on a switch housing (not shown) via support insulators 92. This switch housing encloses an ambient space 94 in which all the components described so far are arranged and in which an extinguishing gas under excess pressure, e.g. SF6 is present.

A first stop surface 96 is formed on the holding flange 90 on its side facing the piston 60 and cooperates with the lower end of the shaft 86 acting as the first counter stop. In a similar manner, a second stop surface 98 is provided on the side of the intermediate base 48 which also faces the piston 60 and which cooperates with the lugs 84 which act as a second counter-stop. A spring ring 100 fastened to the neck 64 and the piston 60 ensure that the actuating member 76 which is movable with the piston 60 only between its first and second locking position 76 ', 76˝ can be moved back and forth.

At the upper end of the second continuous current contact piece 50, a crown-like sliding contact piece 102 is attached approximately at the level of the pump piston 42, the self-resilient contact fingers 102 'of which, under the additional action of a spring 104 encompassing them, rest against the cylinder jacket 20'. A slide ring 106 is provided for guiding the pump cylinder 20 in the upper end region of the second continuous current contact piece 50 encompassing it.

The permanent current contact piece 12 has, at its lower end region facing the pump cylinder 20, covered by a hood 108, resiliently designed and interacting with the pump cylinder 20, continuous current contact fingers 110.

With the exception of the two differences described in more detail below, the embodiment of the compressed gas switch shown only partially in FIGS. 5 and 6 corresponds to the embodiment shown in FIGS. 1 to 4 and described in detail above. In FIGS. 5 and 6, the same reference numerals are used for the same parts as in FIGS. 1 to 4.

FIGS. 5 and 6 show the area of the piston 60 in the on or off position of the switch. On the neck 64 protruding from the piston 60 in the direction toward the top, the actuating member 76 is mounted so as to be displaceable in the axial direction. The locking device 78 defines the first locking position 76 '(Figure 5) and second locking position 76˝ (Figure 6) for the actuator 76. The shaft 86 attached to the nose 84 of the actuator 76 penetrates the disc-shaped valve body 72 and the piston 60 and holds the valve body 72 between the step between the shaft parts 86 'and 86˝ and the lugs 84 clamped firmly with respect to the actuator 76. Is the actuator 76 in its first latching position 76 ', the inlet openings 70 of the piston 60 are closed by the valve body 72' in the closed position 72 '. The valve body 72 cannot act as a flutter valve.

In the intermediate floor 48 of the second continuous-current contact piece 50, through-holes 112 connecting the surrounding space 94 with the blow-out space 40 are provided, which close the through-holes 112 by a check valve 114 in the case of excess pressure in the blow-out space 40 with respect to the pressure in the surrounding space 94. These check valves 114 thus take over the function of the valve body 72, which acts as a flap valve in the embodiment according to FIGS. 1 to 4 the through holes 112 open, communicates with the surrounding space 94 through radial openings 116 in the second continuous current contact piece 50.

The embodiments of the compressed gas switch according to the invention shown in the figures function as follows: In the switch-on position shown in FIGS. 1, 3 and 5, the actuating member 76 is shifted into its first latching position 76 ', so that the valve body 72 is in its closed position closing the inlet openings 70 72 'is located. The majority of the current flows from the connection 14 through the continuous current contact piece 12 the continuous current contact fingers 110 to the pump cylinder 20. From this via the sliding contact piece 102 to the second continuous current contact piece 50 and through the connecting flange 52 to the other connection of the compressed gas switch. The remaining smaller part of the current flows through the fixed contact piece 10 and from this to the erosion contact piece 30 and over the bottom 18 to the cylinder jacket 20 '. From here, this current part flows along the path described above to the other connection of the pressure gas switch.

If the movable contact piece 28 is moved by the drive 67 from its switched-on position (FIGS. 1, 3 and 5) by its switching stroke to the switched-off position (FIGS. 2, 4 and 6), the continuous current contact fingers 110 first separate from the cylinder jacket 20 ', so that the entire current commutates into the fixed contact piece 10 and the erosion contact piece 30. During the subsequent separation of the erosion contact piece 30 from the fixed contact piece 10, an arc is formed which is blown with the compressed gas compressed in the pump chamber 26 by the relative movement between the pump cylinder 20 and pump piston 42 until it is extinguished. Part of the compressed gas flows through the blowing nozzle 16 into the surrounding space 94 and the other part through the passage 36 in the movable contact piece 28 into the blow-out space 40.

When the current is switched off and when small currents are switched off, the compressed gas is not heated or is heated up very little by the arc, so that a negative pressure would like to build up in the blow-out space 40 with respect to the surrounding space 94, since firstly not all of the compressed gas displaced from the pump space 26 flows into the blow-out space 40 and secondly, the blow-out space 40 is enlarged more than the pump space 26 is reduced because the active area of the piston 60 is larger than that of the pump piston 42. However, the build-up of the negative pressure in the blow-out space 40 is prevented by the fact that in the embodiment according to FIGS. 1 to 4 the valve body 72 acts as a flap valve and the surrounding space 94 connects to the blow-out space 40, and in the embodiment according to FIGS. 5 and 6 opens the check valve 114 in order to also connect the surrounding space 94 to the blow-out space 40 in terms of flow. Since in this case no negative pressure can be built up in the blow-out space 40, the drive 67 does not have to do more work than would be the case with a switch without a blow-out space 40.

When medium and large flows are switched off, the pressurized gas pressed out of the pump chamber 26 is strongly heated, with the result that an overpressure is built up in the blow-out chamber 40 with respect to the surrounding chamber 94. The valve body 72 thus remains in its closed position 72 ', and in the embodiment shown in Figures 5 and 6, the check valve 114 is closed. The overpressure in the blow-out space 40 thus supports the drive 67 when switching medium and large currents.

Towards the end of the switch-off stroke, the shaft 86 now runs onto the first stop surface 96, which has the consequence that the actuating member 76 which has been moved with the piston 60 up to this point is displaced from its first detent position 76 'into the second detent position 76stellung Figures 2, 4 and 6). As a result, the valve body 72 is transferred to its open position 72˝ and kept there.

When switching on, in which the movable contact piece 28 together with the blowing nozzle 16, the pump cylinder 20, the piston 60 and the movable actuating member 76 are moved in the upward direction, the pump chamber 26 is enlarged and the blow-out chamber 40 is reduced. The valve body 72, which is now forcibly held in the open position 72˝ by the actuating member 76 which is locked in the second latching position 76˝, keeps the inlet openings 70 clear, so that no excess pressure can build up in the blow-out space 40. As a result, when the drive 67 is switched on, there is no additional work to be done in comparison to a switch without a blow-out space 40. The negative pressure in the pump space 26 is compensated for by sucking in compressed gas through the inlet 22 and by means of the suction passages 54 released by the check valve body 56 under these pressure conditions. Towards the end of the switch-on process, the lugs 84 now run onto the second stop surface 98, which has the consequence that the actuating member 76 is shifted back from its second latching position 76˝ into the first latching position 76 '. As a result, the valve body 72 is transferred from the open position 72˝, which it has assumed during switching on, into the closed position 72 '. Before switching off, the valve body 72 is therefore always in the closed position 72 '.

The pressure gas switch according to the invention supports the drive 67 when switching off medium and large currents and requires no more work from it when switching off small currents and when switching on than with a pressure gas switch without a blowout space 40, without impairing the extinguishing behavior. The compressed gas switch according to the invention thus manages with a drive 67 of low energy.

It is also conceivable to arrange the valve body 72 firmly on the actuating member 76, as shown in FIGS. 5 and 6, and to dispense with through holes 112. In this case, a vacuum is generated in the blow-out chamber 40 when the current is switched off or when small currents are switched built up, which can quickly extinguish the arc, but requires additional work from the drive.

The latching device 78 can of course be designed in different ways. It is thus conceivable to hold the actuating member 76 in the respective latched position by magnetic means. It is also conceivable to move the actuating member from one to the other latching position only in the switched-on or switched-off position of the compressed gas switch. Of course, the latching device for the actuating member can be provided on the blow-out tube of the movable contact piece.

Claims (9)

1. A gas blast switch with a fixed and a movable contact piece (10, 28), positioned in a surrounding chamber (94) having a quenching gas, said movable contact piece (28) being provided with an axial passage (36) leading from its free end and being surrounded by a blast nozzle (16) which is penetrated by the fixed contact piece (10) in the on-position, the intake (22) of said nozzle communicating with a pump chamber (26) which can be pressurised during an off-stroke and is bounded by a pump cylinder (20) and a pump piston (42), the axial passage (36) at the end facing away from the free end of the movable contact piece (28) opening into a blast chamber (40) which is bounded by a cylinder (58) and by a piston (60) which is co-movable with the movable contact piece (28), which blast chamber can be connected to the surrounding chamber (94) via controlled valve means (72) during the switching-on process, characterised in that control means (74) are provided to open and keep open the valve means (72) towards the end of the off-stroke until the on-position is substantially attained during the switching-on process.
2. A gas blast switch as claimed in Claim 1, characterised in that the control means have an actuating mechanism (76) which is movable in the direction of travel of the piston (60) and can be made to act on the valve body (72) of the valve means, said control means also having a locking device (78) with two locking positions (76′, 76˝) for the actuating mechanism (76), said actuating mechanism (76) towards or at the end of the off-stroke being conveyable from a first locking position (76′) corresponding to the closing position (72′) of the valve body (72) into a second locking position (76˝) corresponding to the open position (72˝) of the valve body (72) by striking a first stop (96) and, during the switching-on process shortly before or on attaining the on-position, being conveyable from the second locking position (76˝) into the first (76′) by striking a second stop (98).
3. A gas blast switch as claimed in Claim 2, characterised in that the first stop and the second stop (99, 98) are stationary.
4. A gas blast switch as claimed in Claim 2 or Claim 3, characterised in that the valve body (72) is coupled to the actuating mechanism (76) via a drag link (86, 86′, 86˝) so that in the first locking position (76′) the valve body (72) forms a flutter valve with free passage in the direction of the surrounding chamber (94) into the blast chamber (40).
5. A gas blast switch as claimed in one of Claims 1 to 4, characterised in that the preferably washer-shaped valve body (72) of the valve means cooperates with the piston (60) so as releasably to seal intake apertures (70) provided in said piston.
6. A gas blast switch as claimed in one of Claims 1 to 4, characterised in that the blast chamber (40) is connected to the surrounding chamber (94) via a non-return valve (114) with free passage in the direction of the surrounding chamber (94) into the blast chamber (40).
7. A gas blast switch as claimed in one of Claims 2 to 5, characterised in that the actuating mechanism (76) is positioned in the interior of the blast chamber (40) and is of an annular design embracing the movable contact piece (28) or a neck (64) formed on the piston (60), and in that the locking device (78) in the movable contact piece (28) or in the neck (64) of the piston (60) has a spring-loaded locking member (82), preferably a ball, which member cooperates with two locking grooves (80, 80′) on the actuating mechanism (76).
8. A gas blast switch as claimed in Claim 7, characterised in that the actuating mechanism (76) has a counter-stop element (86) which penetrates the piston (60) and cooperates with the first stop (96) provided outside the blast chamber (40), and in that the second stop (98) is provided inside the blast chamber (40).
9. A gas blast switch as claimed in Claim 2, characterised in that the locking device has magnetic means to hold the actuating mechanism in the first and/or second locking position.

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