HK1062355B - Switching arrangement for low-voltage circuit breakers - Google Patents

Description

Switching device for low-voltage circuit breaker

Technical Field

The invention relates to a switching device for low-voltage circuit breakers with a high rated current, comprising essentially movable switching contacts arranged on a movable contact carrier, fixed switching contacts and a device for cooling, deionizing and extinguishing the switching arc.

Background

Low-voltage circuit breakers with a high rated current have a contact system with a very wide structural size, which is determined by the function. This is related to the continuous current of the switch, irrespective of its blocking capacity, which is generally the same for all switches (irrespective of their rated current) and is designed at a maximum of about 100 kA. The cross section of the contact rail, i.e. the width of the contact rail and the contact system, is therefore determined by the continuous current. In such contact systems, the movable contact is designed as a multiple contact system with a defined number of identical contact rods. These contact beams are conventionally provided with a pre-contact and an arc angle in addition to the main contact itself. This embodiment causes a commutation of the current when the movable switching contact is moved away, i.e. a current is transferred from the main contact to the pre-contact. This generates a slight heat caused by the permanent current, since the permanent current is conducted via the main contacts, which cooperate with the fixed stationary contacts of the switch and are not subjected to the load caused by the arc during switching. The main contacts are burnout-proof and thus maintain a good surface, so their contact resistance is small and thus the heat generated by the continuous current is small.

In the case of circuit breakers for high and very high loads, for example in the case of circuit breakers for limiting the current, the enormous forces caused by the numerous contact rods already present and their contact pressure act on the contact carrier, in particular also on the support of the contact rods in the contact carrier, as a result of which the limit of the material-carrying capacity is reached very quickly in some cases. It is therefore desirable to reduce the total contact force acting on the contact carrier by all contact levers mounted on one hinge pin. In the case of known conventional low-voltage circuit breakers, therefore, a pre-contact is usually provided on the fixed contact side, which, on the basis of its design dimensioning, results in only a certain number of contact rods of the movable contact making contact with the contact. In conventional low-voltage circuit breakers, such fixed pre-contact contacts are narrower than the main contacts and are arranged centrally over the entire contact width. Such a device is disclosed, for example, in EP 0410902B 1. A low-voltage circuit breaker for high rated currents with a movable multiple contact is disclosed, which has a plurality of contact fingers of the same length, which are arranged parallel to one another at small relative distances, and a stationary main contact which, in the on position, interacts with the movable main contact of each individual contact finger. Furthermore, at least one movable arcing contact is provided, which is arranged between the end of the at least one contact finger and the movable main contact. These movable arcing contacts interact with a fixed arcing contact which is designed to concentrate the arc on the center axis of the switching pole. This means that it is arranged centrally and has a narrow structural dimension. This can be seen in particular in fig. 2 of this patent document. Other devices have movable contacts, wherein not all contact bars are provided with precontact contacts. Here, some contact beams without pre-contact contacts are conventionally located on the outside of the multiple contacts. This is the case, for example, in the low-voltage circuit breaker described in DE 19727696.

All these devices have the disadvantage that the bending stress of the bearing pin of the movable contact lever is particularly great, since the force of the contact lever is mainly concentrated in the center.

Disclosure of Invention

The object of the invention is therefore to create a switching device for low-voltage circuit breakers with a high rated current, in which the large forces acting on the contact carrier due to the numerous contact rods and their contact pressure are reduced and in particular a uniform distribution of the forces acting on the bearing pins of the contact rods is achieved.

The object is achieved in that in a switching device for low-voltage circuit breakers, which switching device essentially comprises a plurality of movable switching contacts arranged on a movable contact carrier, a plurality of fixed switching contacts and a device for cooling, deionizing and extinguishing switching arcs, a fixed contact having a pre-contact function and a plurality of movable contact rods with and without pre-contact contacts are provided which are continuous over the entire contact width and are distributed in a defined sequence along the entire contact width in a manner differing from conventional arrangements, wherein at least one contact rod with a pre-contact and at least one contact rod without a pre-contact are arranged in succession in alternation. In other words, conventionally, only the contact levers without precontacting contacts, which are arranged outside the movable switching contact, are arranged distributed along the entire width of the movable contact carrier, i.e. also in the intermediate region. The contact rods can be arranged here in such a way that: a contact rod with a pre-contact and a contact rod without a pre-contact are arranged one after the other along the entire width of the contact carrier.

However, the contact rods can also be distributed: the contact beams with pre-contact contacts and the contact beams without pre-contact contacts are arranged in segments or groups (paketweise) by alternately arranging them one after the other.

Advantageously, the contact beams or contact beam groups (kontake the same) are arranged symmetrically and contact beams without pre-contact contacts are always provided on the outside of the contact carrier.

It is also possible, however, to arrange the contact beams or contact beam groups symmetrically in such a way that a contact beam with a pre-contact is provided on the outside of the contact carrier.

The bending stress and the possible deflection of the highly loaded support pins of the contact rods is thereby reduced or removed from the central region, and the bending force is distributed more uniformly.

When the effective pre-contact contacts are distributed along the width of the contact carrier in such a way that the individual partial switching arcs are distributed locally, a subdivision of the entire arc quenching device into a plurality of partial arc quenching devices arranged next to one another with a plurality of base points for the switching arcs can be achieved. The design of the partial quenching devices in one quenching chamber thus reduces the outlay required for the arrangement of the parallel quenching devices in spatially separated units, and minimizes the overall width of the switch.

Drawings

For a better understanding, the invention is explained in more detail below with the aid of a preferred embodiment, which does not limit the scope of protection.

Figure 1 shows a movable contact support with multiple contacts equipped according to the invention,

figure 2 schematically shows an embodiment in which the contact lever on the movable contact carrier is arranged below the arc extinguishing device,

fig. 3 schematically shows another exemplary embodiment of the arrangement of the contact lever on the movable contact carrier below the arc quenching device.

Detailed Description

Fig. 1 shows a movable contact carrier 1 with multiple contacts for a high-rated low-voltage circuit breaker, having a plurality of movable contact rods 2, 3 which are arranged parallel to one another at a small relative distance. In this case, a part of the contact lever 2, in addition to the main contact 4, has a pre-contact 5, which is arranged between the end of the contact lever 2 designed as the arc angle 6 and the main contact 4. These movable precontact contacts 5 cooperate in a known manner with fixed precontact contacts and main contacts, not shown, like the movable main contacts 4. According to the invention, the contact beams 3, which are not provided with pre-contact contacts 5, are arranged in a defined sequence, which is different from the conventional arrangement, which is limited to the outer region, and are arranged in sections or groups. The arrangement sequence is not limited to the sequence shown in the present embodiment, in which, starting from one side of the contact carrier 1, then two contact beams 3 without pre-contact contacts 5 are seven contact beams 2 with pre-contact contacts 5, then again four contact beams 3 without pre-contact contacts, seven contact beams 2 with pre-contact contacts 5 and two contact beams 3 without pre-contact contacts 5. The different contact levers 2, 3 are arranged symmetrically on the contact carrier 1 in view of an even distribution of the force. This reduces the bending stress and the possible deflection of the supporting pin 12, which is subjected to high loads by the contact rods 2, 3, or moves away from the central region of the supporting pin 12, and distributes the applied bending forces more uniformly.

Fig. 2 shows a schematic illustration of a configuration of the arrangement of the contact levers 2, 3 of the movable contact carrier 1, not shown, below the arc quenching device 7, wherein the contact levers 2, 3 with or without the pre-contact contacts 5 are arranged in groups in a sequence similar to that shown in fig. 1. When the effective pre-contact contacts 5 are distributed as shown along the width of the contact carrier 1 and thus the partial arcs formed are distributed locally, a subdivision of the entire arc quenching device 7 into a plurality of partial arc quenching devices 8, 9, 10 arranged next to one another with a plurality of base points 13, 14, 15, 16 for the switching arc can be achieved. The design of the partial quenching devices in one quenching chamber thus reduces the outlay required for the construction of a plurality of parallel quenching devices in the form of spatially separated units and minimizes the overall width of the switch.

Fig. 3 shows a schematic illustration of a further embodiment of the arrangement of the contact levers 2, 3 of the movable contact carrier 1, not shown, below the arc quenching device 11, in which one contact lever 3 without the precontact contact 5 and one contact lever 2 with the precontact contact 5 are arranged in succession along the entire width of the contact carrier 1. The design of the arc quenching device 11 here suitably corresponds to the desired requirement of a substantially uniform distribution of the switching arc along the entire width of the switching contact.

By distributing the different contact beams uniformly along the contact carrier and thus possibly reducing the number of contact beams provided with precontact contacts, the polarity reversal (Polr  ckwirkung) during the first contact is reduced, so that the power required for switching on the energy store can be reduced. This results in all mechanical components of the switching drive system being subjected to a lower load or in an extension of their mechanical service life. By providing the fixed contact along the entire width of the contact rail, the heating caused by the continuous current is positively influenced. A larger amount of copper will create a larger temperature gradient and thus improve the thermal conductivity. The arc extinguishing device has a better arc extinguishing characteristic by obviously improving the commutation of the current.

Claims (6)

1. Switching device for low-voltage circuit breakers, essentially comprising a plurality of movable contact rods (2, 3) arranged on a movable contact support (1), a plurality of fixed switching contacts and a device (7, 11) for cooling, deionizing and extinguishing the switching arc, characterized in that: a fixed contact with a pre-contact function is provided which is continuous over the entire contact width, and a plurality of movable contact rods (2) with pre-contact contacts (5) and a plurality of movable contact rods (3) without pre-contact contacts (5) are arranged distributed in a defined sequence over the entire width of the contact carrier (1), wherein at least one contact rod (2) with a pre-contact and at least one contact rod (3) without a pre-contact are arranged in succession in an alternating manner.

2. The switching device of claim 1, wherein: the movable contact rods (2, 3) are arranged such that one contact rod (2) with a pre-contact and one contact rod (3) without a pre-contact are arranged one after the other in an alternating manner along the entire width of the contact carrier (1).

3. The switching device of claim 1, wherein: the movable contact rods (2, 3) are arranged such that two or more contact rods (2) with pre-contact contacts (5) and two or more contact rods (3) without pre-contact contacts are arranged in groups one behind the other and alternately.

4. The switching device of claim 1, wherein: the movable contact rods (2, 3) or contact rod groups are arranged symmetrically, and the contact rods (3) without pre-contact contacts are always arranged on the outer side of the contact support (1).

5. The switching device of claim 1, wherein: the movable contact rods (2, 3) or contact rod groups are arranged symmetrically, and a contact rod (2) with a pre-contact (5) is always arranged on the outer side of the contact support (1).

6. The switching device of claim 1, wherein: the entire arc quenching device (7) is designed in the form of a plurality of parallel arc quenching sub-devices (8, 9, 10) having a plurality of base points (13, 14, 15, 16) for the switching arc.