EP0951042B1 - Circuit breaker - Google Patents

Description

Technical area

The invention relates to circuit breakers, as used in power plants, substations and other electrical power supply facilities for switching on and off of operating and overcurrents.

State of the art

There are long known circuit breakers in which the drawn during a cutoff between the switching pieces arc is extinguished by quenching gas from a pressure volume. The pressure is generated by a piston which is driven simultaneously with the second contact piece by a switching drive or even formed by a part thereof, s. z. As a result, however, the switching drive is exposed to a high load, which requires a generous dimensioning of the same. This of course affects the manufacturing cost of the circuit breaker.

A switch according to the preambles of the two independent claims 1 and 6 is known from FR 921.806 A. This switch has a Abbrandschaltanordnung with two along a vertical axis relative to each other displaceable switching pieces and a released when opening the Abbrandschaltanordnung and limited by the two switching pieces arc chamber. When switched off, the arc chamber is connected to an exhaust volume arranged above the arc space via a movable both switching pieces designed as a tube.

Below the arc chamber a communicating with the arc chamber via a plurality of openings pressure chamber is arranged, which contains an ignitable charge of an explosive substance. To open this switch, the explosive is ignited. In this case formed gas serves to drive the movable contact piece and the blowing of a switching arc located in the arc zone.

In GB 742,727 A an electrical switch is described with two mutually displaceable in the vertical direction switching pieces, of which an upper comprises a pressure chamber. The underlying movable contact piece is inserted in the on position of the switch with its free end in the manner of a piston in the pressure chamber. To open an explosive material is ignited in the pressure chamber. In this case formed pressure gases drive the piston-like contact piece down. In this case, a switching arc formed between the two contact pieces is blown with a pressure gas flow guided transversely to the direction of movement of the piston-like contact piece.

Switching devices are also known from EP-B-0 548 390 and US Pat. No. 4,617,436, in which charges of explosive are used in the switching drive, which are ignited to trigger a disconnection. The resulting gas in the explosion acts on a piston, which is in operative connection with a movable contact piece and it drives the same under the action of the gas pressure in the off position. However, the gases produced during the explosion are kept away from the contact pieces and are not used for the blowing out of any arc drawn between them.

There are also fuses known in which an electrical connection is separated by the explosion of an explosive charge. In DE-A-35 37 314, for example, such a fuse is described with a tubular, centrally constricted and surrounded by a pressure chamber bridge conductor, on the outside of which an explosive charge is circumferentially mounted in the pressure chamber. The pressure chamber is lined with a material which emits, after ignition of the explosive charge and the disruption of the bridge conductor under the influence of a forming arc electronegative gas which forms a high pressure extinguishing gas together with the gases generated by the explosion, with the blowing of the arc flows into an expansion space. The use of extinguishing gas-forming powders in fuses is also known from EP-A-0 657 910 and EP-A-0 641 005.

However, fuses must be at least partially replaced after a single cut-out. In the described in DE-A-35 37 314 not only the explosive charge is consumed and destroyed the bridge conductor, the quenching gas is also generated substantially by the action of the arc on the lining of the pressure chamber, which is also used up. In addition, there is likely to be between the emergence of the high pressure Explosive gases and the mainly caused by them flow and the release of electronegative gas triggered only by the arc a time delay, which is not conducive to effective blowing.

Presentation of the invention

In contrast, the present invention seeks to improve generic circuit breakers such that the arc is exposed to a strong quenching gas flow, ohrie that this leads to an additional burden on the switching drive.

This is achieved according to the invention by the features of the two independent claims 1 and 6, which ensure that the arc is exposed to a strong extinguishing gas flow even without the use of mechanical means. In suitable developments of the inventive circuit breaker, the switching drive is not only relieved, but also supported and can be dimensioned correspondingly small, which makes the circuit breaker much cheaper. Under certain circumstances, the switching drive can even be omitted altogether.

Brief description of the drawings

Fig. 1

schematisch einen teilweisen axialen Längsschnitt: durch die Abbrandschaltanordnung eines Leistungsschalters gemäss einer ersten Ausführungsform der Erfindung,

Fig. 2

schematisch einen teilweisen axialen Längsschnitt durch die Abbrandschaltanordnung eines Leistungsschalters gemäss einer zweiten Ausführungsform der Erfindung und

Fig. 3

schematisch einen teilweisen axialen Längsschnitt durch die Abbrandschaltanordnung eines Leistungsschalters gemäss einer dritten Ausführungsform der Erfindung.

In the drawings, several embodiments are shown, which serve only to illustrate the invention. Show it

Fig. 1

schematically a partial axial longitudinal section: through the Abbrandschaltanordnung a Circuit breaker according to a first embodiment of the invention,

Fig. 2

schematically a partial axial longitudinal section through the Abbrandschaltanordnung a circuit breaker according to a second embodiment of the invention and

Fig. 3

schematically a partial axial longitudinal section through the Abbrandschaltanordnung a circuit breaker according to a third embodiment of the invention.

Ways to carry out the invention

The burnup circuit arrangement of a circuit breaker according to a first embodiment of the invention shown schematically in the closed position in FIG. 1 has a fixed first contact piece, which is designed as a contact tulip 1 with resilient contact fingers surrounding a switching axis 2. As a movable second switching piece, a switching pin 3 is provided, which can be moved along the switching axis 2 between the illustrated closed position and a switch-off, in which he is behind him in the closed position contacting sliding tulip 4, adjustable. Between the contact tulip 1 and the sliding tulip 4 is an arc chamber 5, which is taken in the closed position by the switching pin 3 and is surrounded on all sides by a pressure chamber 6. The arc chamber 5 and the pressure chamber 6 are connected via an annular blow opening 7. In the direction of the switching axis 2 close to the arc chamber fifth einschaltseitig a first exhaust volume 8a and ausschaltseitig a second exhaust volume 8b, which are connected in the off position by surrounded by the contact tulip 1 and the idler 4 exhausts 9a, 9b with the same, while they are closed in the off position by the switching pin 3. The circuit breaker may also have rated current contacts, not shown, which are separated at a turn-off in each case before the switching pieces of Abbrandkontaktanordnung.

On the outer wall of the pressure chamber 6, a charge 10 of an explosive material is arranged, which fills the same part and which is ignited at least under certain circumstances in a turn-off. It may also be provided a plurality of distributed over the circumference of the pressure chamber 6 charges. The charge 10 can in any case be pressed in tablet form or else like a cartridge with pulverulent explosive filled in a housing. This can have a wide variety of compositions. However, it should be implemented in its explosion in reaction products that are at least predominantly suitable for arc quenching. In order to avoid environmental pollution is preferred as quenching gas nitrogen.

Suitable for use in switches according to the invention suitable for the environment harmless explosives whose reaction products have a high proportion of nitrogen, especially of so-called airbags, which are widely used as safety devices in motor vehicles, known and also for use in inventive Switches suitable. An example is 21NaN ₃ + KNO ₃ + 4Fe ₂ O ₃ + 2.5SiO ₂ , which in the explosion is converted into 10.5Na ₂ O + 0.5K ₂ O + 4Fe + 2.5SiO ₂ + 4FeO + 32N ₂ . This explosive contains no halogens and is otherwise environmentally friendly, so that the exhaust volumes 8a, b can be open. Another example of a suitable explosive is a mixture of 71.6% SrNiO ₃ , 3.77% V6MO15O60, 3% paraffin, 21.6% guanidine-5,5'-azotetrazolate, which is prepared in 8.2% CO ₂ , 31 , 1% H ₂ O, 43.7% N ₂ and 15.6% SrCO ₃ .

When switching off the switching pin 3 is moved by a switching drive, not shown, down, where it releases the exhaust 9a, which connects the arc chamber 5 with the first exhaust volume 8a. Between the switching pin 3 and the contact tulip 1 while an arc is drawn, which, when the tip of the switching pin 3 passes the sliding tulip 4, commutated on the same, so that it burns between the contact tulip 1 and the sliding tulip 4. The shift pin 3 is further moved down until it releases the exhaust 9b between the arc space 5 and the second exhaust volume 8b.

By temperature and pressure of the arc, the charge 10 is ignited, whereupon the explosive contained in the same in a very short time - about 10 to 30 ms, usually at most 50 ms - is converted into gas, which has a high proportion of quenching gas - above example nitrogen - contains. The gas yield is usually at least 0.2 l / g, normally 0.5 to 1 l / g, so that in the pressure chamber 6, a high pressure is built up very quickly, which then in a strong Gas flow from the pressure chamber 6 via the arc chamber 5 and the two exhausts 9a, b in the two exhaust volumes 8a, b discharges. The arc is intensely blown and erased.

Instead of by direct action of the arc on the charge 10, the ignition of the same can also be triggered by a separate ignition device, which responds to suitable criteria. This offers the possibility of triggering an ignition only if the current exceeds a certain threshold, z. B. 10 times the rated current, if below the threshold a blowing is not necessary or a weak, sufficient for low fault currents blowing by other means is provided. Ignition of charge 10, which requires recharging, can be limited to those cases where it is really necessary.

Another possibility, with which a complicated recharging mechanism can be avoided, is a layering of the charges of the explosive. Between the individual layers of the explosive layers of an electrically insulating material of defined strength for the spatial separation of the same are provided. Under the action of an arc, the uppermost layer of the insulating material evaporates and thus releases the next layer of the explosive, which is then ignited and burns gas-forming. This ignition is usually done by the arc, but other ignition mechanisms are conceivable. For a particularly high-current and long-burning arc Several layers can evaporate and burn off successively. This arrangement of the explosive has the particular advantage that the gas generation over a longer period of time is distributed, so that a particularly intense and long-lasting blowing of the arc is achieved.

In addition, a circuit breaker according to the invention can also be connected in series with a conventional circuit breaker designed for low fault currents, which takes over the interruption of the same up to a certain current intensity, while switching off the inventive circuit breaker is only triggered when a higher fault current occurs.

The burnup circuit arrangement of a circuit breaker according to the invention, shown schematically in FIG. 2, according to a second embodiment corresponds in its basic structure to that according to the first embodiment. In that regard, reference is made to the description of the latter. However, it has in addition several ausschaltseitig to the pressure chamber 6 subsequent, the switching axis 2 surrounding and parallel to the same cylinder 11, in which fixedly connected to the switching pin 3 piston 12 are slidably disposed.

Upon ignition of the charge 10, the pressure build-up in the pressure chamber 6 also has the effect that the pistons 12 in the cylinders 11 are acted upon by a force acting in the disconnection direction. This causes or supports the switch-off movement of the switching pin 3. With respect to the ignition of the charge 10 continue to be the top described possibilities. It can first be moved by a mechanical drive the switching pin 3 so far against the open position until an arc forms, which is sufficient for the triggering of the ignition. The force acting on the piston 12 then supports only part of the switch-off. In addition, the ignition can be triggered elsewhere, for. B. when the switching pin 3 is still in the closed position. The onset of pressure then leads from the beginning to a force acting on the piston 12 force, which supports the entire turn-off or even sufficiently causes sufficient dimensioning of cylinders, pistons and charge, so that can be completely dispensed with a mechanical switching drive.

The burn-up circuit arrangement of a circuit breaker according to the invention, shown schematically in FIG. 3, according to a third embodiment again corresponds in essential features to that according to the first embodiment. However, only one Ausschaltseitig arranged, connected to the arc chamber via an exhaust 9 exhaust volume 8 is present, while Einschaltseitig the arc chamber 5 and connected to the same via a surrounded by the contact tulip 1 round blow opening 7, a pressure chamber 6 is arranged with a charge 10. In the closed position of the switching pin fills the exhaust 9 and with its tip and the lower part of the blow opening 7 in cross section completely. The arc chamber 5 is surrounded by an annular heating volume 13, which is open against the same.

To trigger a switch-off, in turn, for example, when a fault current occurs, which exceeds a certain threshold, the charge 10 is ignited. This in turn leads to a rapid buildup of pressure in the pressure chamber 6, which acts on the switching pin 3, which also acts as a piston here, with a force acting in the Ausschalttrichtung force. He is thereby moved against the Ausschalttrichtung and pressed out of the contact tulip 1, where he draws an arc. As a result of the extinguishing gas flowing into the arc chamber 5, this arc is strongly blown from the outset, but as a rule this will not suffice for a deletion. The quenching gas flows into the heating volume 13, where it is strongly heated by the arc and the pressure increases accordingly. After the switching pin 3 has also released the exhaust 9 to the exhaust volume 8, discharges, especially at a zero crossing, the pressure prevailing in the heating volume 13 pressure by a strong gas flow over the arc chamber 5 and the exhaust 9 in the exhaust volume 8, z. T. also through the blow opening 7 in the pressure volume 6. This blown the arc is vigorously and deleted.

In the context of the invention, many modifications of the embodiments described are possible. For example, several pressure chambers can be provided with charges that z. B. ignited at designated intervals or depending on the position of the switching pin. As already indicated, a combination with a conventional device for blowing is possible, which is sufficient at lower currents and makes an ignition of charges required only for large fault currents.

The pressure chamber can each be relatively small and completely filled by the charge. In the burn-off circuit arrangement according to the third embodiment can be dispensed with the heating volume, if the charge is so dimensioned that the extinguishing gas flow generated during the ignition of the same certainly sufficient for the extinction of the arc.

Mechanical devices for automatically replacing spent cargoes with new ones may also be provided, such as e.g. B. from US-A-4,617,436 is known. For switching on a simple mechanical drive can be provided or, if with the inventive circuit breaker another switch or disconnector is in series, a return spring, which brings the switching pin after switching off immediately in closed position.

LIST OF REFERENCE NUMBERS

1

Contact tulip

2

switching axis

3

switch Probe

4

sliding tulip

5

Arcing area

6

pressure chamber

7

blowing opening

8th; 8a, b

evacuation volumes

9; 9a, b

Exhaust

10

charge

11

cylinder

12

piston

13

heating volume

Claims (7)

1. A circuit-breaker having at least one consumable switchgear arrangement, which comprises a first contact member and a second contact member, which can be shifted relative to the same along a switching axis (2) between a closed position in which it touches the first contact number and an open position in which it is separated from the same in the axial direction and clears an arcing chamber (5) situated between the contact members, having at least one exhaust (9a, 9b) via which the arcing chamber is connected to at least one exhaust volume (8a, 8b), and having at least one pressure chamber (6) which is connected to the at least one exhaust (9a, 9b) via the arcing chamber (5), wherein there is arranged in the at least one pressure chamber (6) at least one charge (10) of an explosive which can be ignited during an opening operation and is converted at least partly into extinguishing gas during the explosion, characterized in that least one pressure chamber (6) surrounds the arcing chamber (5) in an annular fashion and has a blowout opening (7) directed toward the same.
2. The circuit-breaker as claimed in claim 1, characterized in that the at least one charge (10) burns up within at most 50 ms after the ignition.
3. The circuit-breaker as claimed in claim 1 or 2, characterized in that the explosive is converted to gas at at least 0.2 l/g.
4. The circuit-breaker as claimed in one of claims 1 to 3, characterized in that the extinguishing gas consists at least predominantly of nitrogen.
5. The circuit-breaker as claimed in one of claims 1 to 4, characterized in that the at least one pressure chamber (6) is filled only partly by the at least one charge (10).
6. A circuit-breaker having at least one consumable switchgear arrangement, which comprises a first contact member and a second contact member, which can be shifted relative to the same along a switching axis (2) between a closed position in which it touches the first contact number and an open position in which it is separated from the same in the axial direction and clears an arcing chamber (5) situated between the contact members, having at least one exhaust (9) via which the arcing chamber is connected to at least one exhaust volume (8), and having at least one pressure chamber (6) which is connected to the at least one exhaust (9) via the arcing chamber (5), wherein there is arranged in the at least one pressure chamber (6) at least one charge (10) of an explosive which can be ignited during an opening operation and is converted at least partly into extinguishing gas during the explosion, and wherein the at least one pressure chamber (6) adjoins the arcing chamber (5) in the closing direction and the at least one exhaust chamber (8) adjoins the arcing chamber (5) in the opening direction, characterized in that the arcing chamber (5) is surrounded by a annular heating volume which is open towards the arcing chamber (5) and in that the second contact member is constructed as a contact pin (3) which simultaneously acts as a piston by virtue of the fact that in the closed state its tip projects into a blowout opening (7) which connects the arcing chamber (5) to at least one pressure chamber (6), and fills up the cross section thereof at least approximately.
7. The circuit-breaker as claimed in claim 1, characterized in that the at least one ignitable charge (10) is constructed in layers, volatile electrically insulating material being provided between the individual layers.

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