WO2005048282A1

WO2005048282A1 - Arc quenching system

Info

Publication number: WO2005048282A1
Application number: PCT/EP2004/052831
Authority: WO
Inventors: Gunther Eckert; Paul Herma; Wolfgang Leitl
Original assignee: Siemens Aktiengesellschaft
Priority date: 2003-11-11
Filing date: 2004-11-05
Publication date: 2005-05-26
Also published as: NO331047B1; PT1683173E; DE10352934B4; ES2291956T3; EP1683173A1; DE10352934A1; ATE372583T1; EP1683173B1; NO20062712L; DE502004004909D1; CN100468600C; CN1879183A; BRPI0416378A

Abstract

The aim of the invention is to create an arc quenching system for a switching device (1), which ensures low heat build-up and fast quenching of an arc (11) using simple means. Said aim is achieved by providing a current conducting path (13) which comprises an electrically conducting passage to an additional arc guide rail (10) so as to form a conductor loop (10, 13) and is electrically insulated relative to a pair of switching contacts (5, 6). The conductor loop (10,13) is not connected to the pair of switching contacts (5, 6) while being arranged in the area of an interrupter chamber (12) such that a current (I) which drives the arc (11) into the arcing chamber (8) is conducted via the current conducting path (13) when the arc (11) commutates from one of the switching contacts (5; 6) to the additional arc guide rail (10).

Description

description

Arc-extinguishing device

The invention relates to an arc extinguishing device for a switching device according to claim 1.

Such an arc extinguishing device serves to interrupt or extinguish an arc which arises when a pair of contact pieces through which a current flows are opened. When the contact pieces are separated, the current flows over increasingly smaller areas of an associated contact zone and heats them up more and more. Shortly before the actual separation of the contact pieces, a molten bridge is created which finally breaks off in the case of small currents or evaporates in the case of large currents. The current can therefore only continue to flow via an arc in the form of a conductive plasma column.

The strength of the arc is influenced by the amount and type of current switched. In the event of a short circuit in a circuit protected by a miniature circuit breaker, short-circuit currents of up to 15000 A occur, for example. The arc generates temperatures of up to 20,000 K in the switch housing during its burning time, depending on a supply with direct or alternating current however, leads to harmful effects for the switch components. For example, metal and insulating parts can be damaged or destroyed by the action of the arc. As a result, it is necessary to extinguish the arc as quickly as possible in order to minimize the thermal energy conversion.

From DE 35 01 314 AI a multi-pole circuit breaker is known, which is provided in a power supply to a contact with a blow loop to promote arcing; the blow loop is formed in that a supply line, viewed in the direction of arc travel, behind one Fixed contact piece is connected to an arc rail, which has the fixed contact piece. However, the blowing current is permanently flowed through by the operating current of a circuit, which leads to an increased power loss and thus to an increased heating of the circuit breaker. On the one hand, stronger heating requires the use of thermally stable and more cost-intensive materials, and on the other hand an adaptation of the thermal release so that it can compensate for self-heating by means of a correspondingly larger dimensioning of the release path.

It is therefore the object of the present invention to provide an arc extinguishing device which, with simple means, ensures rapid extinguishing of an arc with little self-heating.

This object is achieved by the features of claim 1; advantageous embodiments are the subject of further claims.

By means of a current conductor track, which has an electrically conductive transition to the further arc guide rail in the sense of a conductor loop and is electrically insulated from a switch contact pair, due to a connection-free arrangement of the conductor loop to the switch contact pair in the region of a switching chamber with a commutated arc from one the switch contacts are guided onto the further arc guide rail by a current driving the arc into the arc quenching chamber via the current conductor track; A physical principle of action is used, according to which current-carrying conductors - here a first area of the current conducting path and the arc - repel each other and current-carrying conductors - here a second area of the current conducting path and the arc - attract in the same direction. Due to the loop geometry and the arc running, repulsive forces and forces of attraction act together on the arc and open in a higher arc acceleration in the direction of the arc quenching chamber.

Since current flows through the conductor loop only due to an overload or short circuit in the course of the commutation process, normal operation results in addition to a short current path, low internal resistance and low power loss of the switching device. In the event of a fault, a longer current path, a greater internal resistance and a corresponding current limitation come into play, so that the arc is extinguished reliably and quickly. In addition, a comparatively long service life of a switching device having the arc extinguishing device is achieved using simple and space-saving means.

A current conductor track is advantageously arranged on the further arc guide rail on both sides of the switch contact pair, so that the driving effect on the arc caused by the current is increased with a low use of material. Accordingly, a conductor loop can be arranged on both sides of the switch contact pair, which are electrically conductively connected at least at one loop end.

The shape and position of the conductor loop is advantageously adapted to a switching chamber, with good use of space in the sense of a large effective conductor length being ensured.

The conductor loop advantageously extends into a region of the switch contact pair, which likewise increases the effective conductor length, in particular of a first and a second partial region of the conductor loop. The two subregions each have a position essentially parallel to the arc, so that there is an optimal force effect of the mutually influencing magnetic fields. The conductor loop advantageously extends into a region of the arc quenching chamber, so that the attractive forces influencing the arc are effective right into the arc quenching chamber.

The second section of the conductor loop advantageously has a length which corresponds to the distance between the two arc guide rails from one another in the region of the arc quenching chamber; this favors the force of attraction acting on the arc until the arc enters the arc quenching chamber.

Advantageously, the conductor loop is made in one piece, so that one can benefit from efficient production; the conductor loop can be designed as a stamped-bent part or as a flat-band bent part or as a wire molded part.

Advantageously, one loop end of the conductor loop extends into the area of the arc quenching chamber, which favors a persistence of the arc in the arc quenching chamber.

Advantageously, the other end of the conductor loop is in an electrically conductive connection to a connection terminal, in particular also to a thermal release, so that a sufficient outflow of the current can take place.

The arc guide rail is advantageously arranged in a funnel shape to the further arc guide rail in such a way that the arc is elongated in the direction of the arc quenching chamber and results in an increase in the arc voltage.

The invention and advantageous refinements according to the features of the further claims are described below with reference to in the drawing of exemplary embodiments illustrated, without restricting the invention to this extent; show in it:

1 shows a section of a switching device with a closed pair of switching contacts and an arcing chamber according to claim 1, and FIG. 2 shows a section of the switching device according to FIG. 1 with an open pair of switching contacts.

1 shows a section of a switching device 1 with an arc extinguishing device, which has a schematically illustrated housing 2. The switching device 1 is designed as a circuit breaker and includes, in addition to an electromagnetic release 3, a thermal release 4 and a pair of switching contacts with a fixed contact 5 and a moving contact 6. The fixed contact 5 is placed on an arc guide rail 7 serving as a contact carrier, which at the same time has an electrically conductive connection to a coil of the electromagnetic release 3. The coil in turn leads to a schematically illustrated connection terminal. On the free end, the arc guide rail 7 leads into an arc quenching chamber 8 via a subsequent yoke. The arc guide rail 7 has an ear-shaped configuration in the area after the fixed contact 5, towards the arc quenching chamber 8. The moving contact 6 is fastened on a movable contact arm 9 which is rotatably mounted about an axis, not shown here. Both the electromagnetic release 3 and the thermal release 4 - here a bimetal - can, depending on the fault, cause the movable contact arm 9 to pivot.

A further arc guide rail 10 is provided at a distance from the arc guide rail 7 and has the arc extinguishing chamber 8 in its free-side region. The two funnel-shaped arc guiding Rails 7, 10 together serve for the targeted guiding of an arc 11 according to FIG. 2 into the arc extinguishing chamber 8 receiving the arc 11. The one through the switching contact pair 5, 6 and the two arc guide rails 7, 10 and optionally through an arc entry zone the area defined for the arc extinguishing chamber 8 is referred to as the switching or prechamber 12. The switching chamber 12 has, inter alia, a current conductor track 13 which is provided with a first, second and third partial area 13a, 13b and 13c. The current conductor track 13 has in its first partial area 13a an electrically conductive transition to the further arc guide rail 10 in the sense of a conductor loop 10, 13. The conductor loop 10, 13 is adapted in shape and position to the contours of the switching chamber 12 and can optionally be drawn with the second partial region 13 b partially behind the arc quenching chamber 8. In addition to the common materials, such as copper, aluminum or steel for the conductor loop 10, 13, this can be designed as a stamped and bent part or as a flat strip bent part or as a wire molded part.

The conductor loop 10, 13 is connected to the transition according to FIG. 1 by one of several common joining methods, although the transition can also be carried out in one piece. The conductor loop 10, 13 projects without connection, that is to say without touching the arc guide rail 7 or the movable contact arm 9 including its contacts 5 or 6, into the region of the switch contact pair 5, 6. There is also no contacting of the conductor loop 10, 13 at its intersection. The current conductor track 13 as part of the conductor loop 10, 13 therefore runs back behind the pair of switching contacts 5, 6, with reference to the drawing level in FIG. Of course, such a current conductor track 13 can also be arranged on the other arc guide rail 10 on both sides of the switch contact pair 5, 6. Corresponding to the arrangement shown in broken lines in FIG. 1, the additional current conductor track runs above the switching contact pair 5, 6 in relation to the drawing plane. In addition, one Another embodiment possible, in which there is a complete conductor loop 10, 13 on both sides of the switch contact pair 5, 6. The two conductor loops 10, 13 are electrically conductively connected at one loop end, which leads to a further connection terminal.

According to FIG. 1, the current I symbolized by an arrow is fed in at the connection terminal. The current I flows through the coil of the electromagnetic release 3 over a portion of the arc guide rail 7 up to the contact zone of the switching contact pair 5,6 and from there via the movable contact arm 9 further via a wire to the thermal release 4 and finally to the additional connection terminal to which a consumer can be connected. In normal operation of the switching device 1, that is to say when the switching contact pair 5, 6 is closed, the current flow does not run through the conductor loop 10, 13, so that in addition to a short current path, a low internal resistance and a low power loss of the switching device 1 can also be used. In addition to being a circuit breaker, the switching device 1 can also be designed as a circuit breaker or contactor, for example.

FIG. 2 shows a section of the switching device 1 according to FIG. 1 with the switching contact pair 5, 6 open. The contact position shown here corresponds to a trip or fault in which a short-circuit or overload current flows. The current flow corresponds up to the switching contact pair 5, 6 to the course according to FIG. 1. When the contact pieces 5, 6 are separated, the current flows over increasingly smaller areas of an associated contact zone and heats them up more and more. Shortly before the actual separation of the contact pieces 5, 6, a molten bridge is formed which finally breaks off in the case of small currents or evaporates in the case of large currents. The current I therefore continues to flow via the arc 11 in the form of a conductive plasma column. Since the movable contact arm 9 moves away from the fixed contact 5 with its moving contact 6, but the arc, in order not to tear off, strives for elongation due to its burning property, the arc 11 is commutated - as symbolized by the curved arrow - from the moving contact 6 to the conductor loop 10.13, in particular to the further arc guide rail 10. The arc follows the physical principle of choosing the path of least resistance and jumps to the potential of the conductor loop 10.13. The current conductor track 13 is equipped with an insulation means, such as an insulation plate 14 according to FIGS. 1 and 2 or an insulating housing part, against the commutation of the arc 11 from the moving contact 6 onto the current conductor track 13. The insulation plate 14 extends essentially over the first and second partial areas 13a and 13b of the current conductor track 13. the insulation plate 14 can be guided over the third partial region 13c of the current conductor track 13. There is also a cover for the transition from the further arc guide rail

10 to the current conductor track 13 for deflecting the arc

11 next to the transition, to the further arc guide rail 10, can be provided. The insulation means can also be provided for the additional current conductor track.

After commutation of the arc 11, the conductor loop 10, 13 is in series between the two connection terminals in the current path for a few milliseconds during its burning time. The entire current I, which is caused by an overload or a short circuit, therefore flows via the conductor loop 10, 13 only after commutation. This results in a significant reduction in the heating of the switching device 1, so that the thermal release 4 can be subject to lower requirements with regard to the compensation of the self-heating. In this context, the use of cheaper materials with a lower conductivity, such as steel instead of copper, for the conductor loop 10, 13 also has a cost-saving effect. By arranging the conductor loop 10, 13 essentially in the zone of the switching chamber 12, the arc 11 is magnetically influenced in the sense of bundling or directing the magnetic field. The direction of current flow in the first partial area 13a of the conductor loop 10, 13 is opposite to that of the arc 11. ^{"In the} opposite direction, current-carrying conductors - here arc 11 and first partial area 13a - have mutually repelling magnetic fields, as a result of which the arc 11 is pressed between the two arc guide rails 7, 10 in the direction of the arc quenching chamber 8, since the conductor loop 10, 13 is stationary and Furthermore, the direction of current flow in the second partial area 13b of the conductor loop 10, 13 is equated with that of the arc 11. Conductors with current flowing through them in the same direction - here electric arc 11 and second partial area 13b - have mutually attractive magnetic fields, as a result of which the electric arc 11 between the two arcs - Guide rails 7,10 is drawn in the direction of the arc quenching chamber 8 due to the stationary and rigid conductor loop 10.13.

These effects, caused by the force F on account of the arcuately arranged partial areas 13a and 13b, occur abruptly after the arc commutation. In addition to the repulsive forces, there are also attractive forces on the arc 11, which also forces it due to its inherent dynamics in the direction of the arc quenching chamber and thus supports rapid running-in and quenching. The movement of the arc 11 is greatly accelerated, since the entire overload or short-circuit current flows through the conductor loop 10, 13, before it finally reaches the further connection terminal to a consumer (not shown here) via the third partial region 13 c. The higher the current in the event of a fault, the stronger the force driving the arc. A comparatively long current path that arises causes a large internal resistance and thus a high current limitation; the switching assets of the switching device 1, in particular protective switching device, increases.

The invention explained above can be summarized as follows:

In order to specify an arc extinguishing device for a switching device 1, which ensures simple extinguishing of an arc with a low level of self-heating, there is a current conductor track 13 which provides an electrically conductive transition to the further arc guide rail 10 in the sense of a conductor loop 10 , 13 and is electrically insulated from a pair of switching contacts 5, 6, the conductor loop 10, 13 being arranged without connection to the pair of switching contacts 5, 6 and in the region of a switching chamber 12 in such a way that, when the arc 11 is commutated, one of the switching contacts 5; 6, a current I driving the arc 11 into the arc quenching chamber 8 is guided over the current conductor track 13 onto the further arc guide rail 10.

Claims

claims

1. Arc extinguishing device for a switching device (1), with an arc guide rail (7) and with a further spaced arc guide rail (10) which is used for the targeted guidance of an arc (11) into an arc between the Guide rails (7,10) arranged, the arc (11) receiving the arc quenching chamber (8) are determined, and with a current conductor track (13), which is an electrically conductive transition to the further arc guide rail (10) in the sense of a Has conductor loop (10, 13) and is electrically insulated from a switch contact pair (5, 6), the conductor loop (10, 13) being arranged without connection to the switch contact pair (5, 6) and in the region of a switching chamber (12) such that in the case of a commutated arc (11) from one of the switch contacts (5; 6) to the further arc guide rail (10), a current (I) driving the arc (11) into the arc quenching chamber (8) via the current conductor track (13 ) is performed.

2. Arc quenching device according to claim 1, wherein on both sides of the switch contact pair (5,6) a current conductor track (13) is arranged on the further arc guide rail (10).

3. Arc quenching device according to claim 1, wherein a conductor loop (10, 13) is arranged on both sides of the switch contact pair (5, 6), which are connected in an electrically conductive manner at least at one end of the loop.

4. Arc extinguishing device according to claim 1 to 3, wherein the conductor loop (10, 13) is adapted in shape and position to the switching chamber (12).

5. Arc extinguishing device according to one of the preceding claims, wherein the conductor loop (10, 13) extends into an area of the switch contact pair (5, 6).

6. Arc quenching device according to one of the preceding claims, wherein the conductor loop (10, 13) extends into a region of the arc quenching chamber (8).

7. Arc extinguishing device according to one of the preceding claims, wherein the conductor loop (10, 13) is provided with a first partial area (13a) and a second partial area (13b), each of which is essentially parallel to the arc (11) Have location.

8. Arc extinguishing device according to claim 6, wherein the second partial region (13b) of the conductor loop (10, 13) has a length which is the distance between the two arc guide rails (7, 10) to one another in the region of the arc quenching chamber (8) equivalent.

9. Arc extinguishing device according to one of the preceding claims, wherein the conductor loop (10, 13) is made in one piece.

10. Arc extinguishing device according to one of the preceding claims, wherein the conductor loop (10, 13) is designed as a stamped and bent part or as a flat strip bent part or as a wire molded part.

11. Arc quenching device according to one of the preceding claims, wherein the conductor loop (10, 13) extends with one loop end into the area of the arc quenching chamber (8).

12. Arc extinguishing device according to claim 11, wherein the conductor loop (10, 13) is at its other loop end in an electrically conductive connection to a connection terminal, in particular also to a thermal release (4).

13. Arc extinguishing device according to one of the preceding claims, wherein the arc guide rail (7) to the wide- ren arc guide rail (10) is arranged in a funnel-shaped manner such that the arc (11) is elongated in the direction of the arc quenching chamber (8).

14. Switching device (1), in particular protective switching device, with an arc quenching device according to claim 1.