EP0980085A2 - Power circuit breaker with blast coil operated by the arc - Google Patents

Abstract

The circuit breaker has a fixed contact (5), a movable contact (9) pivotable against two lines (2,3) to provide an electrical connection between them and a blowout coil (20) for magnetically blowing out a light arc (B) formed when the contacts are separated. The blowout coil is switched between a line (3) and a contact element (13) for coupling to the light arc so that after separation of the contacts an electrical connection of the lines occurs via the light arc and blowout coil.

Description

The invention relates to a circuit breaker or also circuit breakers with a fixed contact and with a for establishing a switchable electrical connection two leads against this pivotable moving contact as well as with a blow coil for magnetic blowing resulting electrical when the contacts are separated Arc.

On when a circuit breaker is switched off (Circuit breaker) electrical arc is high Dimensions undesirable, as such on the one hand after the Opening the contact point maintains current flow and thus the switching time is extended. On the other hand, the as Electric arc flashing referred to a comparatively large amount of heat released, which in particular to a strong heating of the switch contacts at the starting point of the Arc leads. This heating can cause injury or destroy the contacts. It is therefore necessary those that inevitably arise during a switch-off process Arc as quickly as possible after it arises to delete.

For this purpose, the switch contacts are usually on the side an extinguishing device, in particular an extinguishing chamber, intended. To the arc from the contact area in the To drive extinguishing device and thus the switching off to accelerate, the arc is often a cross to Arcing path exposed magnetic field. On the electric arc consisting of moving charge carriers with the correct orientation of the magnetic field, a Lorentz force designated force exerted this towards the extinguishing device accelerated. Such a means of a magnetic field forced migration of the arc referred to as magnetic blowing.

It is particularly common in DC applications that magnetic field required for magnetic blowing of a permanent magnet arranged near the arc path to create. Because a permanent magnet is a static magnetic field generated, the effectiveness of the circuit breaker of depends on the direction of the current flowing through this. When the direction of current flow is reversed, the direction is reversed Direction of the Lorentz force acting on the arc. This means that when there is a current flow contrary to the intended Direction of the arc not towards the quenching device is driven, but away from it. When operating the circuit breaker with an alternating current, the Lorentz force also changes alternating. This causes a disadvantageous shutdown considerably disturbed compared to DC operation.

With a so-called all-current circuit breaker, i.e. for a circuit breaker that is polarity independent for direct current and alternating current is suitable, the use of one could a permanent magnet coil for blowing be provided. This blow coil is between the leads of the circuit breaker switched so that the mains current in the Blow coil a magnetic field comparable to a permanent magnet generated. A blow coil has a permanent magnet the advantage that their magnetic field is reversed the direction of current flow also reverses. The simultaneous Inversion of the current flow and the magnetic field direction causes that the resulting Lorentz force is independent of the current flow direction always in the same direction shows. With a suitable arrangement of the coil Arc always driven into the quenching device.

However, the use of a blow coil through which continuous current flows the disadvantage that the blow coil due to the current flow strongly warmed. A heating of the blow coil and thus the interior of the circuit breaker is undesirable. Further is the effect of a blow coil through which continuous current flows comparatively low. This is because the number of turns the continuous current-carrying blow coil due to the im Circuit breaker existing space must be kept low.

The invention has for its object a circuit breaker with a direction independent of the current flow and particularly effective magnetic blowing of a electric arc.

This object is achieved according to the invention by the features of claim 1. According to the magnetic blowing of Arc provided a blow coil, the one hand to a Supply line, in particular the supply line assigned to the moving contact, connected. On the other hand is the blow coil connected to a contact element, which as a derivative for the arc is provided. The contact element is such trained that after separation of the contacts of the arc on Contact element attacks. The blow coil is switched in such a way that over the arc and the blow coil the two leads are conductively connected.

The invention is based on the consideration that a magnetic Blowing in an all-current circuit breaker is particularly effective when the direction of the magnetic field changes always with the current flow direction within the Arc changes. It uses the experience that such current-dependent magnetic field change advantageously by means of a Blow coil is achieved. This could be an improvement compared to a conventional blow coil, if the blow coil is only operated with an existing arc, i.e. flowed through by electricity. To everyone else At times, however, a current flow through the blow coil should be prevented to be an unnecessary sales revenue and thus to prevent undesirable heat generation. As is known the effect described is achieved when the blow coil is contacted by means of the arc. The arc acts as a switch that only turns the blow coil switches on if the arc is present.

Because of the arc operated, and therefore only brief Current flow through the blow coil is during the shutdown process electrical power converted in the blow coil negligible. As a result, comparative small wire diameter a high number of turns the arc operated blow coil can be realized, whereby the effect considerably higher than the effect of a conventional one Continuous-current blow coil is. As a result of the short-term current, the blow coil becomes only slight warmed up.

In a preferred embodiment, this is with the blow coil connected contact element in the form of a catching shoe, which at least the moving contact in its open position surrounds laterally with respect to the arc gap. The Moving contact thus dips into its open position Catch shoe, the arc from the moving contact to the Catch shoe jumps over and turns on the blow field. The contact element is advantageously connected to a Provide permanent magnets, the one to the arc path approximately generates a vertical magnetic field and thus the arc in Deflects the direction of the contact element. That way skipping the arc on the contact element considerably accelerates.

To shorten the switching time, the circuit breaker includes in Appropriate design two tracks that the arc lead from the area of the contacts to an arcing chamber. The area formed between the runners is as Expansion area of the arc.

By means of a parallel to the expansion area of the arc wound blow coil is expediently a special one effective blowing of the arc achieved. Is preferred thereby between the expansion area of the arc and the Blow coil arranged on an insulating wall that would roll over of the arc on the blow coil prevented.

In a particularly expedient embodiment, this closes a first track electrically conductive to the contact element on. The electrical connection of the first track to the contact element encourages the arc to jump over from the contact element to the running rail. In an advantageous The first track is only an alternative except for an insulation distance to the contact element introduced and via a parallel to the blow coil Line connected to the corresponding supply line. On this way the blow coil is only turned on the arc from the contact element to the running rails float. In this version, the current flow through the Blow coil interrupted as soon as the arc hits the running rails skipped. A heating of the blow coil through the electrical power implemented in it further reduced. The blow coil can be particularly space-saving will be realized.

The advantages achieved with the invention are in particular in that by means of an arc-operated blow coil a particularly effective magnetic blowing of an arc takes place because the blow coil only when needed, i.e. operates in the event of an arc. Advantageously is the direction of the Lorentz force depends on the winding direction of the blow coil, but not on the Direction of current flow within the arc.

FIG 1

eine Teilansicht eines Leitungsschutzschalters mit einem Festkontakt, einem Bewegkontakt und einer Blasspule,

FIG 2

einen Schnitt II-II durch den Leitungsschutzschalter gemäß FIG 1,

FIG 3

einen Schnitt III-III durch den Leitungsschutzschalter gemäß FIG 1, und

FIG 4

in einer Darstellung gemäß FIG 1 eine alternative Ausführungsform des Leitungsschutzschalters.

Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. Show:

FIG. 1

1 shows a partial view of a circuit breaker with a fixed contact, a moving contact and a blow coil,

FIG 2

2 shows a section II-II through the circuit breaker according to FIG. 1,

FIG 3

a section III-III through the circuit breaker according to FIG 1, and

FIG 4

1 shows an alternative embodiment of the circuit breaker.

1 shows a partial circuit breaker in a partial view (Circuit breaker) 1, which has two leads 2 and 3 in one Circuit not shown is arranged. The supply line 2 is via a contact bracket 4 with a fixed contact 5 electrically connected. The feed line 3 is over Conductors 6 and 7 electrically connected to a contact arm 8, which carries a moving contact 9 at the end. The contact arm 8 is pivotably mounted about an axis of rotation 10, that in the closed position, not shown, of the circuit breaker 1 the moving contact 9 on the fixed contact 5 rests. The circuit in this case is over the Lead 2, the contact bracket 4, the fixed contact 5, the moving contact 9, the contact arm 8, the conductors 7 and 6 and the Supply line 3 closed.

The circuit breaker 1 is shown with an only hint Trigger 11 provided that when a predetermined occurs Trigger condition a mechanical impulse to the Contact arm 8 and a switch lock, not shown delivers. A short-circuit current, for example, can be used as the trigger condition be fixed within the circuit. As a result the mechanical output from the trigger 11 to the contact arm 8 Impulse is the contact arm 8 in the according to FIG. 1 shown open position pivoted. As a result of this Pivoting of the contact arm 8, which is known in itself Can also be done manually, the fixed contact 5 and the moving contact 9 separated from each other. With the successive Movement of the fixed contact 5 and the movement contact apart 9 creates a so-called electric arc B, where ionization occurs between the contacts 5 and 9 air located the current flow between the Feed lines 2 and 3 are maintained. The arc runs approximately along the connecting line of the contacts 5 and 9 in their open position. This route is therefore referred to as arc gap 12.

The moving contact 9 is in its open position within a catching shoe 13 arranged. The catching shoe 13 is essentially formed as a hollow cuboid from a conductive material. The catching shoe 13 is on a fixed contact 5 facing side surface 14 and on one of the axis of rotation 10 of the contact arm 8 facing side surface 15 open, so that the interior 16 of the catching shoe 13 is a pocket forms, into which the contact arm 8 can be pivoted. At the the Side surface 17 facing away from axis of rotation 10 carries the catching shoe 13 a permanent magnet 18, the north-south axis 19 is aligned at least approximately to the axis of rotation 10. The north-south axis 19 thus runs approximately parallel to the contact arm 8 in its open position. That way achieved that the generated by the permanent magnet 18 (in Fig. 3 shown) static magnetic field S approximately perpendicular stands on the arc gap 12.

The catching shoe 13 is electrically connected to a blow coil 20, which in turn are electrically connected to the feed line 3 is. As if the figures 1 and 2 were viewed together can be seen, the blow coil 20 is in a coil plane 21 wound, which is arranged parallel to a contact plane 22 is. The contact level 22 is defined as the level in which the contact arm 8 is pivotable, and the contacts 5 and 9 and the arc gap 12 contains. Between the blow coil 20 and the contact plane 22 is an insulating wall 23 arranged. This prevents the arc B overlaps the blow coil 20 and this shorts.

The circuit breaker 1 further comprises two rails 24 and 25, which are near each end point of the arc path 12 begin and from there to an arcing chamber 26 extend. The distance between the runners increases 24, 25 in the course of the extinguishing chamber 26. The first running rail 24 assigned to the moving contact 9 is attached to the catching shoe 13 in an electrically conductive manner. The second track 25 is made of a remote from the trigger 11 and beyond the fixed contact 5 extended part of the Contact bracket 4 formed. The rails 24 and 25 extend about within contact level 22 the arc gap 12, the rails 24, 25 and Extinguishing chamber 26 enclosed area is as an expansion area 27 of the arc B.

When contacts 5 and 9 are separated, arc B - as indicated in FIG. 1 - along the arc path 12 between the fixed contact 5 and the moving contact 9. In the area of the moving contact 9, the arc B comes into effect of the static magnetic field 5 of the permanent magnet sketched in FIG 18. On those consisting of moving load carriers Arc B is a by means of the magnetic field S. Lorentz force F1 perpendicular to the arc path 12 and perpendicular to the magnetic field direction prevailing within the catching shoe 13 exercised.

As can be seen from FIG. 3, the magnetic field direction is within of the catching shoe 13 approximately parallel to the north-south axis 19 of the permanent magnet 18. The arc B is due to the Lorentz force F1 towards a side wall 28 or 29 of the Catch shoe 13 displaced. The direction of the Lorentz force is F1 - depending on the direction of current flow within the arc B - either on the side wall 28 or diametrically opposite aligned with the opposite side wall 29. After the arc B has jumped onto the side wall 28 or 29, the current flow now takes place via the fixed contact 5 and the arc B and via the catching shoe 13. From there it is fed to the feed line 3 via the blow coil 20. The arc B thus automatically switches the Blow coil 20, which is now about to the contact plane 22 vertical magnetic field M generated. Under the influence of this Magnetic field M is the arc B with another Lorentz force F2 acts on the arc B in the direction the rails 24,25 acted upon. Under the effect the Lorentz force F2, the arc B jumps from the fixed contact 5 on the adjacent second rail 25 or from the Catch shoe 13 on the associated first running rail 24. Then the arc is along the expansion area 27 supplied to the quenching chamber 26 where the arc B is extinguished becomes.

After extinguishing the arc B, the leads 2 and 3 electrically isolated. Since there is a reversal of the current flow direction the direction of current flow within the arc B. within the blow coil 20 and thus the direction reverses the magnetic field M, the direction depends on Lorentz force F2 only from the winding direction of the blow coil 20, but not on the direction of current flow. The sense of winding the blow coil 20 is chosen such that the direction the Lorentz force F2 on the expansion region 27 of the arc B is aligned.

4 shows an advantageous development of the circuit breaker 1. In contrast to the embodiment shown in FIG 1 here the first running rail 24 is not directly connected to the catching shoe 13 connected. Rather, there is between the running rail 24 and the catching shoe 13 an insulating distance 30 is formed. The Track 24 is connected to the by means of a separate line 31 Supply line 3 connected. This version has the advantage that after the arc B has skipped onto the track 24 the blow coil 20 is de-energized. Another heating up the blow coil 20 and thus the circuit breaker 1 avoided.

Claims (8)

Miniature circuit breaker with a fixed contact (5) and with a movable contact (9) that can be pivoted against it to establish a switchable electrical connection between two supply lines (2, 3) and with a blow coil (20) for magnetic blowing of one when the contacts (5, 9) are separated ) resulting electric arc (B), characterized in that the blow coil (20) is connected between a feed line (3) and a contact element (13) for coupling to the arc (B) in such a way that after separation of the contacts (5,9 ) an electrical connection of the feed lines (2, 3) takes place via the arc (B) and the blow coil (20). Miniature circuit breaker according to claim 1, characterized in that the contact element is designed as a catching shoe (13) surrounding the moving contact (9) in its open position at least laterally with respect to an arc gap (12). Circuit breaker according to Claim 1 or 2, characterized in that the contact element (13) is provided with a permanent magnet (18) which generates a magnetic field (5) which is approximately perpendicular to an arc gap (12). Miniature circuit breaker according to one of Claims 1 to 3, characterized by two running rails (24, 25), each electrically connected to a supply line (2, 3), for guiding the arc (B) to an arcing chamber (26), the between the running rails (24 , 25) formed expansion area (27) of the arc (B) widens towards the quenching chamber (26). Miniature circuit breaker according to Claim 4, characterized in that the blow coil (20) is wound in a coil plane (21) parallel to the expansion region (27) of the arc (B). Miniature circuit breaker according to Claim 4 or 5, characterized in that a first running rail (24) is attached to the contact element (13) in an electrically conductive manner for contacting it. Circuit breaker according to Claim 4 or 5, characterized in that an insulating distance (30) is formed between a first running rail (24) assigned to the contact element (13) and the contact element (13). Miniature circuit breaker according to one of Claims 1 to 7, characterized in that an insulating wall (23) is arranged between the blow coil (20) and the contacts (5, 9).

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