EP0601941B1 - Modular circuit breaker for DC - Google Patents

Description

The present invention relates generally to a set of electrical equipment. The invention relates more particularly to a set of modular electric switchgear, this set including at least one alternating current circuit breaker.

There are sets of electrical devices made up of a number of different electrical devices, each electrical device having an identical or similar external shape, so that any of these electrical devices can be mounted indifferently on a suitable support. (see for example DE-B-1 022 298). When an installer has such a set of electrical equipment, he can easily produce an electrical panel by mounting side by side, on an appropriate common support, electrical equipment chosen from this set.

Most often, in an electrical panel of an electrical installation of the low voltage or medium voltage type supplied by the sector, there are a large number of circuit breakers for alternating current. However, it may also be necessary to combine a small number of DC circuit breakers. For obvious economic reasons, it is preferable that all of these electrical equipment, in particular the AC circuit breakers and the DC circuit breakers, come from the same supplier and even from the same manufacture.

One of the technical difficulties encountered in the realization of an alternating current circuit breaker lies in the arrangement of an internal system at circuit breaker allowing the extinction of the electric arc which is established during the tripping which follows a short circuit. Such an arc extinguishing system is well known in the prior art and it consists in establishing a circuit bypassing the electrical contact, this circuit comprising a series of deionization plates, an arc extinguishing chamber being formed. inside the loop of this branch circuit.

It has been observed for a long time that if one operates such a circuit breaker in direct current, this circuit breaker does not function correctly because the electric arc does not extinguish for low values of direct current. A technical solution to this problem has been known for a long time, this solution consisting in having, in an area of the circuit breaker located laterally with respect to the arc extinguishing chamber, a magnetic means for creating a magnetic field in the extinguishing chamber arc, this magnetic field being directed transversely. The magnetic means can be a permanent magnet or a magnetic coil. In order to increase the intensity of the magnetic field, it is sometimes preferred to have a magnetic means on each side of the arc extinguishing chamber (see for example DE-U-1 884 948).

The object of the present invention is to improve the structure of a modular DC circuit breaker.

According to the invention, there is provided a set of modular electric switchgear assemblies including alternating current circuit breakers, in which all the electric switchgear have a similar external shape in order to be able to be mounted side by side, the assembly comprising at least an accessory consisting of a housing having an external shape similar to that of the others electrical equipment of the assembly and containing a magnetic field generation means, the magnetic field propagating outside the housing at at least one side wall of the housing and substantially perpendicular thereto, so that, when an alternating current circuit breaker and said accessory are mounted side by side, the magnetic field supplied by the accessory crosses an arc extinguishing chamber of the alternating current circuit breaker in order to be able to operate this circuit breaker in direct current.

• la figure 1 est une vue en coupe transversale simplifiée d'un système d'appareillages électriques selon la présente invention ;
• la figure 2 est une vue simplifiée d'un élément formant disjoncteur représenté sur la figure 1, cette vue étant prise en coupe suivant la ligne I-I de la figure 1 ;
• la figure 3 est une vue de face simplifiée d'un autre montage possible du système d'appareillages électriques selon l'invention.

These objects, characteristics and advantages, as well as others, of the present invention will be better understood during the detailed description of an exemplary embodiment which will follow, illustrated by the appended figures among which:

• Figure 1 is a simplified cross-sectional view of an electrical appliance system according to the present invention;
• Figure 2 is a simplified view of a circuit breaker element shown in Figure 1, this view being taken in section along line II of Figure 1;
• Figure 3 is a simplified front view of another possible assembly of the electrical equipment system according to the invention.

In Figure 1, there are generally two distinct components 1, 2 which are arranged side by side on a mounting bracket (not shown). Element 1 is a conventional alternating current circuit breaker and element 2 is an accessory which is particular to the present invention and the function of which will be described later. The alternating current circuit breaker 1 is a conventional circuit breaker which can be used in general in a low voltage electrical installation. In fact, in an installation electrical, it is common practice to have side by side a large number of various electrical devices and among these, there are mostly AC electrical circuit breakers such as that shown in Figure 1. If one wishes use the alternating current circuit breaker 1 as a direct current circuit breaker, we know that it is necessary to create, in the zone of formation of the electric arc, a transverse magnetic field. Element 2 is an accessory according to the invention which makes it possible to use the alternating current circuit breaker 1 as a direct current circuit breaker by the simple fact of attaching the specific accessory 2 to the alternating current circuit breaker 1. The accessory 2 is , according to the invention, consisting of a housing of a non-magnetic material, for example plastic. The housing 3 has a general external shape which can be similar to the general external shape of the circuit breaker 1. However, its width need not be the same as that of the circuit breaker 1 and, preferably, its width may be more low. In fact, the only shape constraints of the housing 3 are those which make it possible to mount and fix the accessory 2 on a support for electrical equipment (not shown). The housing 3 comprises two substantially flat and relatively thin side walls 4, 5. In FIG. 1, the side wall 5 which is situated on the right is therefore applied against a left side wall 6 of the circuit breaker 1.

A magnetic field generation means 7 is fixedly disposed inside the housing 3, interposed with minimum clearance between the side walls 4 and 5. This magnetic field generation means 7 can be constituted either by a magnet permanent either of a magnetic coil. In the example shown in the figures, this magnetic field generation means is a magnet 7, and in the following text we will say "magnet" to mean "magnetic field generation means", for the sake of brevity. In the case where this means 7 is a magnetic coil, the latter is supplied electrically from the outside by means of electrical terminals (not shown) arranged at the rear of the accessory 2 so as to be able to continuously supply the coil magnetic when accessory 2 is mounted on a fixed support of an electrical installation (not shown).

The side walls 4 and 5 of the housing 3 of the accessory 2 also include protrusions directed inwards 8 which make it possible to retain and position the magnet 7 inside the housing 3.

We see in Figure 1 that the magnet 7 produces a magnetic field B which propagates outside the housing 3 in a manner substantially perpendicular to the side wall 5 of the housing 3, that is to say perpendicular to the wall lateral 6 of the circuit breaker 1. On the other hand, the zone of maximum intensity of this magnetic field B when it crosses the circuit breaker 1 is preferably located in the region of arc formation in the circuit breaker mechanism of the circuit breaker 1.

We can see in particular in Figure 2 the position of the zone of maximum intensity of the magnetic field B (hatched area) with respect to the mechanism of the circuit breaker 1. In Figure 2, we distinguish in fact schematically the essential parts d 'a conventional circuit breaker such as that shown at 1 in Figure 1. In this mechanism, there is essentially a fixed contact 21, a movable contact 22, a thermal trip device 23, a trip device electromagnetic 24 and an arc extinguishing chamber with deionization plates. The magnetic field B must have its maximum intensity at the level of contacts 21 and 22.

In FIG. 3, a simplified representation is shown, in front view, of a possible assembly using a set of electrical apparatuses according to the invention, this assembly comprising two alternating current circuit breakers 1A, 1B arranged side by side, a first accessory 2A placed on the left and against the circuit breaker 1A on the left and a second identical accessory 2B placed on the right and against the circuit breaker on the right 1B. It is understood that the accessory 2 according to the invention can be associated with an alternating current circuit breaker 1 by being disposed against it either to its right or to its left. However, in a variant not shown, one could consider arranging an accessory 2 so that the magnet 7 is disposed in the housing 3 of the accessory 2 to provide a significant external magnetic field at a single side of the accessory 2. In this case, the circuit breaker having to be associated with the accessory 2 in order to be able to operate in direct current would be disposed against the accessory, only on this same side in order to be effectively crossed by the magnetic field.

The width of the electrical equipment, for example AC circuit breakers 1, can be for example 18 mm and, in this case, the accessory 2 which is intended to be associated with these electrical equipment can have a thickness of 9 mm or 18 mm. On the other hand, the side walls 4 and 5 of the housing 3 of the accessory 2 are preferably relatively thin, for example with a thickness of less than 2 mm, so that the magnet 7 is located at the smallest possible distance of the active area of the electrical equipment located next to and against the accessory 2. It is relatively easy to produce such relatively thin side walls 4 and 5 because these side walls, as well as the entire housing 3, can be made of plastic and because these side walls are not generally not subject to significant mechanical stress. However, in an alternative embodiment not shown, one could consider placing the magnet 7 in the housing 3 of the accessory 2 so that a flat side face of the magnet or of the magnetic coil 7 is flush with the level of an external flat lateral surface of the housing 3 of the accessory 2.

In another variant not shown, two magnetic field generation means may be provided at the two opposite lateral faces of the accessory, the magnetic orientations of these two magnetic field generation means being substantially the same in order to add up their effects.

The invention is not limited to the embodiments which have just been described, but it encompasses all the modifications and variants which could be envisaged without departing from the scope of the present invention as claimed.

Claims (5)

1. An assembly of assemblable modular electrical switchgear units including AC circuit breakers (1), in which all the electrical switchgear units present a similar external shape in order to be able to be fitted side by side, characterized in that the assembly comprises at least one accessory (2) formed by a case (3) presenting an external shape similar to that of the other electrical switchgear units of the set and housing a means for generating a magnetic field (7), the magnetic field (B) propagating outside the case (3) at the level of at least one side wall (5) of the case and appreciably perpendicularly to the latter, in such a way that, when an AC circuit breaker (1) and said accessory (2) are fitted side by side, the magnetic field (B) supplied by the accessory flows transversely through an arc extinguishing chamber of the AC circuit breaker in order to be able to make this circuit breaker operate in direct current.
2. The assembly according to claim 1, characterized in that the means for generating a magnetic field (7) is a permanent magnet which is housed in the case in such a way as to be arranged close to at least one of the thin side walls (4, 5) of the case.
3. The assembly according to claim 1, characterized in that the means for generating a magnetic field is a permanent magnet which is housed in the case in such a way as to be flush with at least one external side face of the case.
4. The assembly according to claim 1, characterized in that the means for generating a magnetic field is a magnetic coil which is housed in the case and which is supplied electrically by means of electrical supply terminals arranged on the case.
5. The assembly according to any one of the foregoing claims, characterized in that two means for generating a magnetic field are provided at the level of the two opposite side faces of the accessory and that the magnetic orientations of these two means for generating a magnetic field are appreciably the same in order to add their effects together.

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