EP1225610B1 - Arcing contact arrangement for a circuit breaker - Google Patents

Abstract

A power switch has a central switching pin (3) that fits into a fixed contact. At the centre of the pin is a spring loaded element (30) with a tip (29) that normally seals the contact area. When the switch opens arcing occurs and gas pressure rises. If the pressure level exceeds a limit the centre element moves to open a path (28) for gas to escape.

Description

Technical area

The invention relates to a Abbrandschaltanordnung according to the preamble of claim 1, which is particularly suitable for use in circuit breakers, which are used for switching on and off of operating and overcurrents in plants for the generation and distribution of electrical energy.

State of the art

From the EP-A-0 146 671 is a circuit breaker with a Abbrandschaltanordnung the generic type is known in which is used when increasing the high currents of the resulting gas arc pressure in the arc chamber to enhance the Beblasungswirkung. For this purpose, the inner cavity of the one, movable, tubular contact piece is connected via radial outlet openings with a quenching gas containing pump space, which is determined by one with the contact piece with movable cylinder and a stationary piston and the separated with switching pieces via blowing channels with the Arc space communicates. The prevailing after the separation of the switching pieces in the arc high pressure propagates through an inlet opening at the free end of the movable contact piece and the cavity and the outlet openings in the pump chamber and increases the pressure prevailing in this serving for arc extinguishing gas.

At high turn-off currents, a very high pressure is built up in the arc chamber, which results in a high mechanical stress on the components surrounding the arc chamber. The latter must be made correspondingly solid and are therefore relatively expensive to manufacture. Since the mass of the movable Schaltstuck with moving components and prevailing in the pump chamber, acting between the piston and the cylinder gas pressure significantly determine the required breaking capacity of the switch drive, a correspondingly high-performance switch drive must be used for the shutdown of high currents.

In EP-A-0 004 213 a circuit breaker is described with a Abbrandschaltanordnung having two hollow contact pieces and a blinding coil and an arc runner. When switching off a stream is initially formed between the free ends of both switching pieces a switching arc, which commutes in the course of further shutdown with one of its two feet from the free end of one of the two switching pieces on the arc running ring, the current to be disconnected now through the blower coil and the arc running ring to be led. The switching arc which is generated as a result of electromagnetic forces forms pressurized gas by heating insulating gas in a quenching chamber arranged between two exhaust chambers. This compressed gas is guided in two oppositely directed flows through the two hollow contact pieces in the two Auspuffräume and extinguishes the arc, whereby the interruption of the current to be disconnected is ensured. In order to allow a sufficiently high pressure build-up in the quenching chamber to extinguish the arc when switching off a low-power current, is in the two hollow Shift pieces each arranged a valve. Below a threshold value of the pressure, the two valves seal the quenching chamber against the two exhausts. Above the pressure limit, the two valves open at the same time, thus enabling an effective arc blowing even when interrupting low-power currents.

Presentation of the invention

The invention is based on the object to provide a Abbrandschaltanordnung of the aforementioned type, which is in comparatively simple and weight-saving dimensioning of their components in a position to turn off even very high currents.

This object is achieved according to the invention with a consumable switching arrangement having the features of claim 1.

In the case of very large currents to be switched, the closure element is displaced out of its basic position under the action of the gas pressure prevailing in the arc chamber and releases the connection between the inlet opening and the outlet opening or the outlet openings, so that a pressure relief from the arc chamber into an exhaust space can take place. The present invention thus enables a targeted limitation of immediately after the separation of the contact pieces occurring pressure increase in the arc chamber, which allows even with a provided for switching off very large currents Abbrandschaltanordnung the components surrounding the arc space lighter and design the switch drive for a smaller breaking capacity.

Preferred further developments of the inventive circuit breaker form the subject of the dependent claims.

Brief description of the drawings

Fig. 1

einen axialen Längsschnitt durch die Abbrandschaltanordnung eines Leistungsschalters mit den Schaltstücken in geschlossenem Zustand,

Fig. 2

in einer der Fig. 1 entsprechenden Darstellung die Abbrandschaltanordnung kurz nach dem Trennen der Schaltstücke,

Fig. 3

in einer der Fig. 1 entsprechenden Darstellung die Abbrandschaltanordnung mit den Schaltstücken in geöffnetem Zustand,

Fig. 4

in vergrössertem Massstab die Schaltstücke der Abbrandschaltanordnung im in der Fig. 1 gezeigten Zustand,

Fig. 5

in vergrössertem Massstab die Schaltstücke der Abbrandschaltanordnung im in der Fig. 2 gezeigten Zustand,

Fig.6

in einer der Fig. 4 entsprechenden Darstellung eine Variante der in den Fig. 1-5 gezeigten Ausführungsform mit einer anderen Ausgestaltung des beweglichen Schaltstückes, und

Fig. 7

die Schaltstücke der Ausführungsform gemäss Fig. 6 kurz nach ihrer Trennung.

In the following the invention will be explained in more detail with reference to figures, which represent only exemplary embodiments.
Show it

Fig. 1

an axial longitudinal section through the Abbrandschaltanordnung a circuit breaker with the switching pieces in the closed state,

Fig. 2

in one of the Fig. 1 corresponding representation of the burn-off circuit arrangement shortly after the separation of the contact pieces,

Fig. 3

in one of the Fig. 1 corresponding representation of the burn-off switching arrangement with the switching pieces in the open state,

Fig. 4

on an enlarged scale, the switching pieces of Abbrandschaltanordnung in in the Fig. 1 shown condition,

Fig. 5

on an enlarged scale, the switching pieces of Abbrandschaltanordnung in in the Fig. 2 shown condition,

Figure 6

in one of the Fig. 4 corresponding representation of a variant of the in the Fig. 1-5 shown embodiment with another embodiment of the movable contact piece, and

Fig. 7

the contact pieces of the embodiment according to Fig. 6 shortly after their separation.

Ways to carry out the invention

The in the Figures 1-3 shown Abbrandschaltanordnung a rest not further illustrated circuit breaker with the exception of the formation of the movable contact pin in terms of construction and arrangement of the components in the Fig. 3a of the DE-A-198 16 505 illustrated burn-off arrangement.

The consumable switching arrangement 1 has two contact pieces 3 and 4 aligned in the direction of a switching axis 2. The switching piece 3 is an axially movable switching pin, which by means of a switch drive, not shown in the direction of arrow A between a closed position ( Fig. 1 ) and a switch-off position ( Fig. 3 ) is displaceable. The other switching piece 4 is formed as a fixed contact tulip, which is mounted in a central opening of a partition wall 5 and a plurality of arranged around the switching axis 2 and obliquely downwardly directed against the latter elastic contact fingers, which are separated by slots. In its closed position, the switching pin 3 projects into the contact tulip 4 in and is touched by their contact fingers from the outside ( Fig. 1 ). The contact tulip 4 opposite a nozzle 6 surrounding the switching axis 2 is arranged from an electrically insulating material, which has the shape of an upwardly narrowing funnel and is fixed in a central opening of a further partition wall 7. The partition wall 7 closes a first exhaust space 8a upwards.

In the in the Fig. 3 between the switching pin 3 and the contact tulip 4 is then an arc chamber 9, in which an arc 10 is formed during the separation of the contact pieces 3, 4 between them ( Fig. 2 ). The arc chamber 9 is surrounded by an annular heating volume 11 which communicates with the arc chamber 9 via a ring-shaped blow slot 12 which separates the contact tulip 4 from the nozzle 6. To the outside, the heating volume 11 is closed by a peripheral wall of an electrically insulating material. The heating volume 11 is connected via blow channels 13 in the partition wall 7 with blowing cylinders, not shown, in which actuated by the switch actuator blow pistons are arranged. In the outlet of each blow duct 13 in the heating volume 11, a check valve 14 is installed.

At the top of the arc chamber 9, a pressure chamber 15 connects, which is connected to the arc chamber 9 by an opening formed by the ends of the contact fingers of the contact tulip 4. The pressure chamber 15 is limited by an above the contact tulip 4, annular cover 16 and a cap 17, both made of electrically insulating material. The cover 16 and the spaced cap 17 form between them with respect to the Switching axis 2 rotationally symmetrical return channel 18 which extends from the pressure chamber 15 on all sides radially outward and is then guided in the axial direction to the heating volume 11. In the outlets of the return channel 18 in the heating volume 11, a check valve 19 is installed in each case. The pressure chamber 15 is connected by a number of uniformly distributed over the circumference of the exhaust pipes 20 with a second exhaust chamber 8b. In addition, discharge openings 21 are provided in the cap 17, which connect the return channel 18 with the second exhaust chamber 8b and are closed by a piston 22 of a pressure relief valve 23 serving as a safety valve. These pistons 22 are pressed by disc springs 24 in the discharge openings 21.

In the following, taking into account the 4 and 5 the structure of the switching pin 3 explained in more detail.

In the front, hollow cylindrical portion of the switching pin 3, a cavity 25 is formed in its interior. This has an opening 27 provided on the switching tip 26 and a plurality of outlet openings 28 distributed on the circumference of the switching pin 3. The latter are arranged in the direction of the switching axis 2 at such a distance from the inlet opening 27 that they open into the first exhaust space 8 a, as soon as the switching pin 3 is released from the contact tulip 4 during the switch-off. For closing the inlet opening 27, a closure element 29 is provided which is displaceably guided in the cavity 25 in the direction of the switching axis 2. The closure element 29 is connected to a guide pin 30, which is guided in a guide 31 in the switching pin 3. The guide pin 30 is supported with a plate 32 on a compression spring designed as a closing spring 33, which is housed in a further cavity 34 in the interior of the switching pin 3. The closure element 29, the guide pin 30 and the plate 32 are made of an electrically insulating material, such as polytetrafluoroethylene (PTFE).

Hereinafter, the operation of the consumable switching device 1 according to the Fig. 1-5 in addition to the previously mentioned DE-A-198 16 505 Reference is made.

Im in the Fig. 1 and 4 shown switching state engages the switching pin 3 in the contact tulip 4 a. In this case, the inlet opening 27 is closed at the switch tip 26 by the closing element 29, which assumes its front end position in this basic position under the action of the closing spring 33.

When switching off the not shown nominal current contacts of the circuit breaker are separated from each other first. After disconnecting the rated current contacts, the current commutates to the burn-up circuit arrangement 1. Now, the switching pin 3 is pulled out of the contact tulip 4. Between the latter and the switching pin 3, an arc 10 is formed, which extends through the arc chamber 9, which is opened by the movement of the switching pin 3 away from the contact tulip 4 ( Fig. 2 and 5 ). The arc 10 has a known manner, a pressure build-up in the arc chamber 9 and the heating volume 11 result. This pressure build-up is supported by the insulating gas pumped into the heating volume 11 via the blow channels 13 and the pinch pressure of the electric arc 10.

Exceeds when turning off a very large current during the turn-off movement of the switching pin 3 acting on the closure element 29, caused by the pressure in the arc chamber 9 and the heating volume 11 force the closing force of the closing spring 33, the closing element 29 is against the force of the closing spring 33rd moved back from its front end position in a rear end position, and already shortly after the separation of the contact pieces 3, 4 and in a phase of the switch-off movement of the switching pin 3, in which the tip 26 is still between the nozzle 6 and the contact tulip 4 ( Fig. 2 and 5 ). By this pushing back of the closing element 29, the connection between the inlet opening 27 and the outlet openings 28 in the switching pin 3 is released and there is a pressure relief from the arc chamber 9 and the heating volume 11 in the first exhaust chamber 8a, as in the Fig. 2 and 5 indicated by the arrows B. As soon as the pressure in the heating volume 11 or in the arc chamber 9 is reduced to such an extent that the force acting on the closing element 29 in the opening direction is smaller than the closing force of the closing spring 33, the latter moves the closing element 29 back into its front end position, in which it Inlet opening 27 closes again.

The pressure of the insulating gas in the heating volume 11 is still high enough after a pressure relief over the interior of the switching pin 3 to effect a deletion of the arc 10 in a known manner. In the Fig. 3 the burn-up switch assembly 1 is shown after extinguishing the arc and with the switching pieces 3, 4 in the fully open state.

With the described targeted pressure relief can be shortly after the separation of the contact pieces 3, 4 a To achieve regulation of the pressure build-up in the arc chamber 11. This avoids that when switching off very high currents at which the pinch pressure of the arc 10 is large, the arranged in the heating volume 11 or this surrounding components are exposed to a very high mechanical stress. These components can therefore be dimensioned easier. The pressure relief valve 23 only has the function of a safety valve and has no influence on the actual switch-off.

If, when switching off a comparatively low current, the pressure building up in the heating volume 11 is not sufficiently large to urge the closing element 29 away from the inlet opening 27 against the closing force of the closing spring 33, the connection between the inlet opening 27 and the outlet openings 28 remains closed and There can be no pressure reduction over the interior of the switching pin 3. The pressure of the insulating gas required in such a case for extinguishing the arc 9 thus remains. At the arc 10 facing surface of the held in its forward end position closing element 29, which consists as mentioned of an electrically insulating material, a burn-off takes place. The gases generated thereby contribute in a desired manner to increase the pressure in the heating volume 11.

In the 6 and 7 is a variant of the Fig. 1-5 shown Abbrandschaltanordnung 1 shown, in which the contact piece 3 is made of a different material. Corresponding parts are therefore in the 6 and 7 same as in the Fig. 1-5 designated.

In the embodiment according to the 6 and 7 consists of the closure element 29, the guide pin 30 and the plate 32 made of an electrically conductive, erosion-resistant material, for example of a tungsten-copper alloy. The closure element 29 is in at least one place in electrically very good conductive connection with the switching pin 3. In the illustrated embodiment, this electrically conductive connection is made via disposed in the guide 31 contact blades 35.

The in the 6 and 7 Burn-off switching arrangement shown, the operation is the same as that of the embodiment according to the Fig. 1-5 , is preferably used in circuit breakers with which very high short-circuit currents must be disconnected. The arc 10 has a surface which is larger around the surface of the closing element 29 than the surface formed solely by the switching pin 3, which means that the current density at the arc base points does not become too high. The consumable switching arrangement according to the 6 and 7 is also suitable for switches with which very often small currents (usually rated currents) are turned off. In such switches, the electrically conductive closure element 29 relieves the switching pin 3 of the consequences of the burn-up and thus contributes to an increase in its life.

In a third, not shown embodiment, the closure element 29 is in its front end position at a distance from the inlet opening 27, but still between this and the outlet openings 28 are arranged. This means that even in this embodiment, the closure element 29 in its basic position in which it is held by the closing spring 33, the compound between the inlet opening 27 and the outlet openings 28 keeps closed. This connection is the same as in the embodiments according to the Fig. 1-7 only released when the gas pressure in the arc chamber 9 is large enough to cause a repression of the closing element 29 in its rear end position against the force of the closing spring 33.

This third embodiment, whose operation is the same as that of the other two embodiments, has the advantage that because of the short distance to be traversed by the closing element 29, the connection between the inlet opening 27 and the outlet openings 28 is released very quickly. This is of particular advantage in cases where the pressure increase in the heating volume 11 or in the arc chamber 9 takes place very rapidly. For the choice of the material for the closure element 29 (and also the guide pin 30 and the plate 32), above all the required mechanical stability is crucial. In any case, a burn-off-resistant plastic or a burn-off-resistant metal is to be used for the closure element 29, since the gases acting on the closure element 29 are very hot.

It is understood that the burn-off switching arrangements described above can also be formed differently than shown in the context of the invention. For example, it is possible to accommodate the pressure relief arrangement with the displaceable closing element 29 in a cavity in the fixed contact piece.

The inventive Abbrandschaltanordnungen with a new design of a switching piece can not only in circuit breakers of the in the DE-A-198 16 505 shown Art be used, but also in circuit breakers of other suitable design.

LIST OF REFERENCE NUMBERS

1

consumable

2

switching axis

3

first contact piece (switching pin)

4

second contact piece (contact tulip)

5

partition wall

6

jet

7

partition wall

8a, 8b

exhaust space

9

Arcing area

10

Electric arc

11

heating volume

12

blow slot

13

blow

14

check valve

15

pressure chamber

16

cover

17

cap

18

Return channel

19

check valve

20

exhaust pipe

21

relief opening

22

piston

23

Pressure relief valve

24

Disc springs

25

cavity

26

Switching pen tip

27

inlet port

28

outlet

29

closing

30

guide pins

31

guide

32

Plate

33

closing spring

34

cavity

35

Multilams

Claims (12)

1. Erosion switch arrangement for a circuit breaker, which has two contact pieces (3, 4) which can be moved relative to one another along a switching axis (2) between a connected position, in which they touch one another, and a disconnected position, in which they are separated from one another by a switching gap in the axial direction and, with one another, define an arcing area (9), having a cavity (25) which is provided in the interior of the one, first contact piece (3), is connected on the one hand to an inlet opening (27), which is provided at the free end of this first contact piece (3) and points towards the other, second contact piece (4), and is connected on the other hand to at least one outlet opening (28), which is at a distance from the inlet opening (27) in the direction of the switching axis (2) and is provided in the first contact piece (3), and having a nozzle (6) which surrounds the contact piece axis (2), is composed of an electrically insulating material and through which the first contact piece (3) is drawn during disconnection from the connected position to the disconnected position, with a closure element (29) being provided, which is arranged in the cavity (25) in the first contact piece (3), can be moved in the direction of the switching axis (2) and, in a basic position, is held under the influence of an elastic resetting element in a front limit position in which it closes the at least one outlet opening (28) with respect to the inlet opening (27) and from which it can be moved in the direction away from the inlet opening (27) to a rear limit position, against the force of the resetting element, by the influence of the gas pressure in the arcing area (9) during disconnection of the contact pieces (3, 4), in which rear limit position it releases the connection between the inlet opening (27) and the at least one outlet opening (28), which opens into an exhaust area (8a) after disconnection of the contact pieces (3, 4), to be precise in a phase of the disconnection movement of the first contact piece (3) in which its free end is still located between the nozzle (6) and the second contact piece (4).
2. Erosion switching arrangement according to Claim 1, characterized in that, in its basic position, the closure element (29) closes the inlet opening (27).
3. Erosion switching arrangement according to Claim 1, characterized in that, in its basic position, the closure element (29) assumes a front limit position which is located between the inlet opening (27) and the at least one outlet opening (28).
4. Erosion switching arrangement according to one of Claims 1 to 3, characterized in that the closure element (29) is guided longitudinally by means of a guide (31) which is provided in the first contact piece (3).
5. Erosion switching arrangement according to one of Claims 1 to 4, characterized in that the resetting element is a closing spring (33).
6. Erosion switching arrangement according to one of Claims 1 to 5, characterized in that a plurality of outlet openings (28) are provided, originating from the cavity (25) and arranged around the circumference of the first contact piece (3).
7. Erosion switching arrangement according to one of Claims 1 to 6, characterized in that the cavity (25), which extends in the direction of the switching axis (2) is formed at the front end (26) of the first contact piece (3).
8. Erosion switching arrangement according to one of Claims 1 to 7, characterized in that the closure element (29) is connected to a guide bolt (30), which is guided longitudinally in the first contact piece (3) and is supported on the resetting element that is accommodated in the interior of the first contact piece (3).
9. Erosion switching arrangement according to one of Claims 1 to 8, characterized in that the closure element (29) is composed of an electrically insulating material.
10. Erosion switching arrangement according to one of Claims 1 to 8, characterized in that the closure element (29) is composed of an electrically conductive material, and is electrically conductively connected to the first contact piece (3).
11. Erosion switching arrangement according to one of Claims 1 to 10, characterized in that the second contact piece (4) is arranged in a fixed position, and the first contact piece (3) can be moved in the direction of the switching axis (2) by means of a switch drive.
12. Erosion switching arrangement according to one of Claims 1 to 11, characterized in that the first contact piece (3) is in the form of a switching pin.

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