EP1548773A1 - Arc extinguishing installation for a circuit breaker with a double break - Google Patents

Abstract

A magnetic casing (91) fits around a pre-chamber so as to amplify magnetic blowing action on an electric arc formed between the pre-chamber's first (51) and second (61) electric arc running rails. Inserted into an arc-quenching circuit, a blowing loop runs parallel to an electric arc running rail in sections. An independent claim is also included for a safety switch with a two-way interrupter switch.

Description

TECHNICAL AREA

The present invention relates to the field of power switches for Low-voltage distribution networks. It relates to an arc quenching device for Circuit breaker with double break according to the preamble of patent claim 1.

STATE OF THE ART

In low-voltage distribution networks, installation switch-in switches serve the fast and easy Reliable protection of low-voltage cables, motors, apparatus and systems against the consequences of overload and short-circuit currents. They exhibit in the Generally a thermal actuator with a bimetal and a electromagnetic release with a coil and a punch on and off preferably a contact arrangement with double interruption.

In such switching devices is for the life and switching capacity of crucial importance that the opening of the contacts resulting arc not stuck to the contact pieces, but as quickly as possible in one Extinguishing chamber area is guided, where a cooling and extinguishing of the arc he follows. Any persistence of the arc on the contact pieces, also in the Millisecond range, leads to increased burnup and wear of the contact pieces.

A normal circuit breaker has a contact point, which consists of a fixed and a movable contact piece is formed. The contact point is in one so-called pre-chamber, to which a quenching chamber with a Arc splitter stack connects. The base points of the arc are of the fixed contact piece and the movable contact piece via arc guide rails passed to the arc splitter stack. The arc widens immediately after the contact opening, and the inlet velocity of the arc in the Arc splitter stack is dependent on the so-called own blowing, i. the by the arc itself generated magnetic blowing field, the pressure conditions in the Arc, the shaping of the guide rails and the choice of contact material.

From EP-A 649 155 a generic circuit breaker with Double interruption known in which in the arc extinguishing an additional Electromagnetic blower loop is provided to accelerate the arc run. This blowing loop, which is only current during the switch-off process, is symmetrical to a partition that separates two extinguishing chambers and geometrically parallel to the Arc guide rails formed. By a parallel current flow in the blower loop and the adjacent guide rails becomes the electromagnetic force on the arc intensified and accelerated his movement, ultimately results in a higher Switching capacity.

In EP-A-0 212 661 is a current limiter for medium or high voltage applications described in which an arc between two arc guide rails runs away from a switch. Due to the special design of the low-inductive Guide rails, the resistance in the arc is significantly increased, so that a series-connected disconnector the circuit can be interrupted easily. To accelerate the arc movement, this is due to the turn-off current itself magnetic field generated by a magnetic core around one of the guide rails is appropriate.

PRESENTATION OF THE INVENTION

Object of the present invention is in a circuit breaker with Double break the acceleration of the two by a shutdown movement of a Switching contact generated arc to optimize targeted. This task is done by an arc quenching device with the features of claim 1 and a Circuit breaker with the features of claim 10 solved. advantageous Embodiments are evident from the dependent claims.

The core of the invention is, by a suitable magnetic sheath the magnetic fields in the arc and thus on the arc acting and this driving in the direction of the splitter stacks Lorentz force strengthen. As a result, the arc moves faster, the contact erosion is reduces and the Abschaltleistung ultimatively increased. By the inventive separate magnetic sheath need the arc guide itself no Magnetic properties have more and therefore can non-magnetic, the arc movement favoring copper are produced.

Preferably, the magnetic jacket made of steel, for example, is realized, by a one-piece, one-sided open molding with U-profile so on a bridge-side Arc running rail is slipped, that the arc space or the Antechamber is completed on three sides by the molding. That on the arc acting magnetic field of the current flowing in the arc run-off current, i. the so-called own blowing, is thereby reinforced. In addition, such a Easy to manufacture a molded part and onto the arc runner during the assembly process Attach.

In a preferred embodiment of the invention is in a only during the Shutdown of the circuit breaker current-carrying and the two arc comprehensive arc extinguishing a blow loop inserted. The latter is arranged in sections parallel to an arc track and is of a Flowed through which points in the same direction as the turn-off in the adjacent arc guide rail. As a result, the magnetic blowing effects of two currents are accumulated on the arc. The U-shaped magnetic sheath comprises or preferably also surrounds this rail parallel Blasschlaufenabschnitt.

Preferably, the blown loop is geometrically or material technically with equipped with current-limiting features. Since the blown loop in nominal operation, i. When the switch contact is closed, no current flows, this affects the self-impedance the switch is not and hinders due to their low initial or cold resistance of a few mΩ also the commutation of the arc to the corresponding Arc run rails not. After commutation of both arcs is also the blow loop flows through current, as a result increases their impedance and limited the turn-off current.

For switches with double break the blow loop is formed so that Both arcs are favored to a similar extent, for example by a with respect to the extinguishing chamber partition symmetrical design of the blow loop or by two electrically connected in parallel, each associated with an arc Blasschlaufen. In any case, each arc or two atria assigned a separate magnetic sheath, which at the same time as magnetic Shielding of the arcing space opposite to that in the other arcing space dominating magnetic fields.

In a preferred embodiment, the U-shaped magnetic shell is through a pre-chamber insulation made of Plexiglas, for example, from the actual arc chamber separated. This will cause the arc to roll over prevents metallic coat. In addition, the insulation can outgassing properties have, i. Remove arc-extinguishing gases.

Preferably, the pre-chamber insulation has a in the arc region protruding bulge to reduce the prechamber volume. By the Reduced volume will cause a pressure loss of the gases in the arc area counteracted and the arc prevented from broadening. especially the Feet of the arc remain compact and thereby heat the Arc guide rails, which is conducive to movement of the arc.

The bulge preferably has a V-shaped profile which extends in the direction of Extinguishing chamber opens and follows approximately the contour of the guide rails. This will ensured that the two arc base points move at the same speed and the Arc itself before entering the quenching chamber beyond its maximum, through the Distance of arc guide rails given length expands. So all are Splitter plates equally involved in the division and extinction of the arc.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 eine Lichtbogenlöscheinrichtung umfassend zwei Vorkammern mit je einem magnetischen Mantel und je einer Blasschlaufe,

Fig.2 eine Detailansicht einer ersten Vorkammer, und

Fig.3 einen Schnitt durch eine erste Vorkammer mit einer Vorkammerisolation.

The invention will be explained in more detail with reference to embodiments in conjunction with the drawings. These show in perspective

1 shows an arc quenching device comprising two prechambers each having a magnetic jacket and a respective blow loop,

2 shows a detailed view of a first antechamber, and

3 shows a section through a first pre-chamber with a pre-chamber insulation.

The reference numerals used in the drawings are in the list of reference numerals summarized. Basically, the same parts with the same reference numerals Mistake.

WAYS FOR CARRYING OUT THE INVENTION

Fig.1 shows in oblique view a section of a single or multi-pole Circuit breaker with two series-connected switching contacts per pole. A first Terminal 10 leads through the coil of a short-circuit current release 100 and a first connection conductor 11 to a first fixed contact 21. This is in closed Switch position (not shown) in electrical contact with a first bridge contact 31 of a movable fork-shaped contact bridge 3. A second bridge contact 32 of Contact bridge 3 is in closed switch position in contact with a second Fixed contact 22, which via a second connecting conductor 12 on to a not shown overcurrent release and leads to a second terminal. Both each formed by a fixed and bridge contact switching points is always a first or second pre-chamber 41,42 assigned.

In the event of a short circuit or overcurrent caused by the short-circuit current release 10 or the overcurrent release the contact bridge 3 moves away from the fixed contacts 21,22, form between the fixed contacts 21,22 and the bridge contacts 31,32 two in opposite directions from the cut-off current through arc, the bridge side Feet points in the sequence of the bridge contacts 31,32 on the bridge side Arc running rails 61,62 commute or "jump". Due to the shape of the (in the Arrangement according to Figure 2 "lower") bridge-side arc runners 61,62 and the one connected to the fixed contacts 21,22 (in the arrangement of Figure 1 "upper") terminal-side arc runners 51,52 favors, migrates a first arc between the first terminal side arc runner 51 and the first one bridge-side arc runner 61 in the direction of a first Arc splitter stack 71, while a second arc between the second terminal side arc runner 52 and the second bridge side Arc track 62 moves toward a second arc splitter stack 72. When switched off, the arcs are thus generated by the self-generated magnetic fields along the arc runners in extinguishing chambers urged on the quenching plates cooled, divided into partial arcs and deleted.

2, a detail of the first pre-chamber 41 is shown in another perspective, wherein the splitter stack between the widened ends of the first two Arc guide rails 51,61 was omitted. The inventive magnetic Sheath 91 with U-shaped cross-section, which consists of a magnetically effective Material such as iron or steel preferably as a one-piece shielding plate is arranged so that it is the arc space, which between the first arc guide rails 51,61, laterally closes. A back 911 of the Jacket is located along the first bridge-side arc guide rail 61, while the side surfaces 912 of the shell towards the first connection side Arc guide rail 51 extend. The magnetic jacket 91 bundles this Arc magnetic field and drives the arc in addition in the direction of Chutes.

As can also be seen from FIG. 1, each of the two prechambers 41, 42 is a separate one magnetic jacket 91.92 assigned. This will change the arc area between the both arc guide rails 51, 61; 52.61 magnetic with respect to the outside space and in particular with respect to the other prechamber 42; 41 shielded. Next is in Fig.1 between the first bridge-side running rail 61 and the second bridge-side Running rail 62, a first blower loop 81 is provided. In the event of triggering flows Abschaltstrom from the first to the second arc through this first blower loop 81. Sie comprises at least one Lorentz section located inside the jacket 91, which part geometrically arranged parallel to the first bridge-side arc run rail 61 and in which the current flow direction is the same as in the adjacent one Arc running rail 61. As a result, the electromagnetic Lorentz force on the first arc, which moves it in the direction of the first splitter stack 71, strengthened.

The blower loop 81 is preferably equipped with turn-off current limiting properties. A current-limiting behavior can be achieved, for example, by the selection of materials, all conductors with an electrical resistance in question, which increases with increasing current, and including in particular the known as PTC resistor (positive temperature coefficient) metallic alloys based on Ni, Co, Fe, such as NiCr, NiMn, NiFe, NiCrMn, NiCo, NiCoFe, CoFe, CrAlFe, or ceramic materials. Another such PTC thermistor is based on a polymer composite whose polymer matrix is filled with a mixture of carbon, a metal such as Ni, and a boride, silicide, oxide or carbide such as TiC ₂ , TiB ₂ , MoSi ₂ , V ₂ O ₃ . It is important that the initial or cold resistance is not too high and the commutation of the arcs on the bridge-side rails 61,62 and the concomitant training of the arc extinguishing circuit is not hindered.

In Fig.3 a section through the first pre-chamber 41 is shown, whereby from the first magnetic cladding 91 only the cut surface of his back 911 is visible. Generally The arc running properties are strongly dependent on the contour of the arc guide rails 51.61 dependent. Due to the apparent narrowing between the upper and lower Guide rail over a large part of the antechamber, the arc is optimal accelerated. Since in the widening of the guide rails 51, 61 the magnetic suction effect is already effective by the quenching plates 71 of magnetic material, is a Stability of the arc on the arc guide rails prevented and a instantaneous entry of the same possible.

Between the guide rails 51,61 and the magnetic jacket 91 is a Prechamber insulation 411, which has substantially the same cross section as the cladding 91 and this isolated from the arc region. A prechamber insulation as Injection molded part is suitably introduced before the assembly of the shell in this or slipped over the guardrails. A bulge 412 within the prechamber insulation directs the ionized gases on the guide rails, which are heated by the gases and let the arc base point run. The bulge 412 reduces the Distance perpendicular to the sectional plane of Figure 3 between the side surfaces of the insulation, i.e. the clear width of the arc chamber, by 30 to 50%. The bulge according to 3 has the shape of an elongated elevation, which is V-like in the direction of the Löschblechpakete 71 opens.

LIST OF REFERENCE NUMBERS

10

First connection terminal

100

Short circuit current release

11

First connection conductor

12

Second connection conductor

21

First fixed contact

22

Second fixed contact

3

Contact bridge

31

First bridge contact

32

Second bridge contact

41

First antechamber

411

prechamber

412

bulge

42

Second antechamber

51

First connection-side arc runner

52

Second connection-side arc runner

61

First bridge-side arc runner

62

Second bridge-side arc runner

71, 72

Arc splitter packages

81

First blow loop

82

Second blow loop

91

First magnetic coat

911

move

912

side surface

92

Second magnetic coat

Claims (10)

Arc quenching device for circuit breaker with double break, comprising two fixed contacts (21, 22), which can be connected to terminals of the circuit breaker and can be contacted by two bridge contacts (31, 32) of a movable contact bridge (3), two subchambers (41, 42), each separated by a partition wall, each having two arc runners (51, 61; 52, 62), of which one connection-side arc runner (51, 52) is connected to a fixed contact (21, 22) and a bridge-side arc runner (61 , 62) is designed to take over an arc from the contact bridge (3), two extinguishing chambers adjoining the antechambers, each having an arc splitter stack (71, 72) which is connected to the respective arc runners (51, 61; 52, 62), characterized in that a magnetic jacket (91) is provided for reinforcing the magnetic forces acting on a first arc formed between the first bridge-side and the first connection-side arc guide rail (51, 61). Arc quenching apparatus according to claim 1, characterized in that the magnetic shell (91) is a one-piece molded part having a spine (911) and two parallel side surfaces (912) forming a U-shaped profile, the spine (911) being adjacent to the first one Bridge side arc runner (61) comes to rest and the side surfaces (912) to the connection side arc runner (51) show. Arc quenching device according to claim 2, characterized in that a first blowing loop (81) connected to the two bridge-side arc runners (61, 62) is provided for generating a Lorentz force directed towards the first splitter stack (71) on the first arc. Arc quenching device according to claim 3, characterized in that the magnetic jacket (91) comprises the first bridge-side arc runner rail (61) and a geometrically parallel arranged Lorentz section of the blower loop (81). Arc quenching device according to claim 3 or 4, characterized in that the first blowing loop (81) has current-limiting properties. Arc quenching device according to claim 3 or 4, characterized in that both prechambers (41, 42) are shielded from each other by an associated magnetic jacket (91, 92). Arc quenching device according to claim 2, characterized in that a Vorkammerisolation (411) of an electrically non-conductive material surrounding the arc region and the arc relative to the magnetic jacket (91) isolated. Arc quenching device according to claim 7, characterized in that on at least one of the arc region facing inner walls of the Vorkammerisolation (411) has a bulge (412) is provided. Arc quenching device according to claim 8, characterized in that the bulge (412) of the prechamber insulation has a V-shaped structure opening towards the quenching chambers. Double-breaker circuit breaker comprising two terminals (11), a short-circuit current release (100) acting on a contact bridge (3) and a Arc quenching device according to one of the preceding claims.

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