SHORT-CIRCUITING DEVICE FOR USE IN LOW-VOLTAGE AND MEDIUM-VOLTAGE SYSTEMS FOR THE PROTECTION OF PROPERTY AND PERSONS

摘要

The invention relates to a short-circuiting device for use in low-voltage and medium-voltage systems for the protection of property and persons, comprising: a switching element, which can be operated by the tripping signal of a fault detection device; two mutually opposite contact electrodes having power supply means, which contact electrodes can be brought into contact with an electrical circuit having connection points at different potential; furthermore, in at least one of the contact electrodes, a movable contact part, which is under mechanical preload and executes a movement to the further contact electrode with the assistance of spring force in the event of a short circuit; and a sacrificial element as a spacer between the contact electrodes, with an electrical connection between the sacrificial element and the switching element on the one hand and one of the contact electrodes on the other hand, in order to deliberately cause current-flow-induced thermal deformation or destruction of the sacrificial element. According to the invention, the movable contact part is in the form of a hollow cylinder which is closed on one side, and a spring for generating preload is inserted in the hollow cylinder. The hollow cylinder is movably guided in a complementary cutout in the first contact electrode, a sliding contact thus being formed. In the region of the base of the closed hollow cylinder, the cylinder wall of said hollow cylinder transitions into a cone at the outer circumference. Furthermore, a first pin-like extension, opposite to which a second pin-like extension insulated from the contact electrodes is situated, extends within the hollow cylinder, proceeding from the base. The sacrificial element, in the form of a bolt or screw, is arranged between the first and the second pin-like extension. A cutout, which has an internal cone and is matched to the external cone of the movable contact, is provided in the second contact electrode. The external cone and the internal cone form a bounce-free short-circuit contact region having frictional locking and interlocking connection on account of plastic deformation which occurs. Furthermore, according to the invention the switching element is designed as an auxiliary short-circuiter on the basis of an electric match.