DE1064591B - Plasma bridge switch - Google Patents

Description

GERMAN

In the case of compressed air switches, an arc is drawn when the contact pieces are separated, which occurs at the zero crossing of the current goes out. The ionized gas between the contact pieces is generated by compressed air blown away. For effective deionization it is important that the regeneration of ions during the deletion time is prevented if possible. These are mainly caused by impact ionization by the electrons emitted from the glowing arc roots. So there is the problem, education to prevent arc roots. These arcing points arise from the fact that the Separation of the contact pieces at the last contact points high current densities occur which melt the material of the contact pieces and the ignition of the arc.

It is known, in the case of gas pressure switches, in particular for switching off high voltages, the tip of the To moderate the recurring voltage by the fact that the ion distances up to the occurrence of the recurring Voltage can be weakly ionized by an additional ion source.

The invention relates to a method for carrying out a current interruption in electrical Switches with separating contacts, through which the formation of arcing points is prevented during the separation process. It is therefore particularly suitable for performing arc quenching for circuit breakers or circuit breakers. In the method according to the invention, the Cutting point short-circuited during the cutting process by a plasma bridge and this after the Separation displaced in a manner known per se by non-ionized air. The plasma can e.g. B. can be generated by an arc discharge.

The displacement of the plasma after the end of the separation process can be achieved by flushing with compressed air take place.

In a further embodiment of the method according to the invention, the plasma is displaced by utilizing the pressure conditions occurring during the switching process.

To further explain the invention, reference is made to the drawing, in which some exemplary embodiments for switches are shown schematically, whose mode of operation is based on the method of the invention; it shows

1 shows the principle of the method according to the invention in three partial figures,

Fig. 2 shows a device according to the invention with an auxiliary arc arrangement for generating the Plasmas, also in three partial figures.

In Fig. 1, the two tubular contact pieces are denoted by 1 and 2. Plasma bridge switch is located inside the tubes

Applicant:

Siemens-Schuckertwerke
Aktiengesellschaft,
Berlin and Erlangen,
Erlangen, Werner-von-Siemens-Str. 50

Dipl.-Ing. Johann Thomas, Erlangen,
has been named as the inventor

a plasma, which is indicated by rings and minus-plus signs. The external circuit is indicated in FIG. 1 a by the consumer 3 and the power source 4. Fig. 1 b shows the situation immediately after opening the switch. A plasma bridge is now located between the two contact pieces 1 and 2 , which takes over the current transport and prevents current concentrations from occurring at the last contact points of the switching tube, which result in the above-mentioned phenomena.

Fig. 1 c shows the last phase of the separation process.

The plasma bridge is z. B. eliminated by flushing with compressed air and thereby a complete power interruption been brought about. Since no arc root points have arisen, the Compressed air purging practically complete deionization of the separation space and thus an improved one Extinguishing effect achieved.

In Fig. 1, the supply of the plasma is indicated by arrows. The generation of the plasma can, for. B. be done with an arc arrangement. This can either be operated by a second circuit, but it can also be in the main or shunt of the circuit to be interrupted. The last-mentioned case is shown in the three sub-figures of FIG. The two switching tube pieces are designated by 11 and 12 , respectively. As in FIG. 1, the plasma is indicated by rings and minus-plus signs. Directly upstream of the one switching tube is an arc arrangement with the preliminary contact 13 and the secondary contact 14.

909 610/292

Claims (5)

The mode of operation of the arrangement is as follows: By opening the pre-contact 13, an arc is created which ionizes the surrounding air. This plasma formed in this way is blown into the switching tube by compressed air and can form the plasma bridge when the switching tubes are opened (FIG. 2 b). The opening takes place in such a way that the switching tube 11 is pulled upwards. At the same time, the pre-contact is closed and the auxiliary arc is extinguished. At the same time, the auxiliary arc arrangement is short-circuited via the secondary contact 14 (FIG. 2 c). The figures described above are purely schematic. In the practical implementation, you will arrange the ion source as close as possible to the separation point and optionally the separation tube, the z. B. can also be plate-shaped, run with a multiple interruption. Furthermore, it is advisable to choose the dimensions so that a plasma column with the largest possible cross-section and therefore the lowest possible resistance can be formed. In a preferred embodiment of the device according to the invention, the two contact pieces and the arrangement for generating the plasma, that is to say e.g. B. the auxiliary arc assembly, housed in a closed, provided with a check valve space. In this case, the pressure distributions occurring in the aforementioned space during the separation process can be used to remove the plasma after the separation process has ended. This is based on the fact that the arc ignition at the pre-contact increases the air pressure in the switching tube considerably and the air in the lower part of the switching pressure is pushed out so that the plasma formed in the upper part flows in and is then available at the separation point of the switching pieces to form the plasma bridge . Fresh air is sucked into the switching tube through the non-return valve and through this the plasma bridge is flushed away again. The dimensioning of the separators can also be chosen so that the pressure conditions occurring in the interrupter under the effect of the acoustic natural frequency of the air column have an effect in terms of plasma transport and a favorable conductivity characteristic of the gas in the switch room. Patent claims 1. Method of carrying out a current interruption in electrical switches with it separating contacts using an ion plasma, characterized in that the So strong around the separation point immediately before the mechanical separation of the separators is ionized that when initiating the separation, the separation point by a plasma bridge short-circuited and this after termination of the mechanical separation in per se known Way is displaced by non-ionized air. 2. The method according to claim 1, characterized in that the plasma by an arc discharge is produced. 3. The method according to claim 1 or 2, characterized in that the displacement of the plasma takes place by means of a compressed air purging. 4. The method according to claim 1 or 2, characterized in that the during the switching process of the pre-contact of an auxiliary arc arrangement for plasma generation occurring Pressure distributions are used to displace the plasma and that for this purpose the switch arrangement including the auxiliary arc assembly housed in a closed, provided with a check valve room is. 5. Switch for carrying out the power interruption according to one of the preceding claims, characterized in that the two contact pieces are tubular or plate-shaped and its interior space is used to supply the plasma. Considered publications:
German patent specifications No. 419 300, 445 581,
! 5 971, 955 618. 1 sheet of drawings ® 909 610/292 8.