Patent ID: 8445804
Filing Date: 2013-05-21
Classification: H01H

Abstract:
1. A vacuum cartridge for an electrical protection apparatus, said cartridge comprising an enclosure of substantially cylindrical shape closed by two end-plates, two contacts extending axially inside the enclosure, at least one of these contacts being movable and connected to an operating mechanism, and mounted for sliding between a closed position in which flow of current is enabled, and a position in which the contacts are separated and withstand voltage between them, and at least one conducting shield around at least one of the contacts, said at least one conducting shield comprising a mid-potential shield, a first partial shield, and a second partial shield, said mid-potential shield being radially between the two contacts and the enclosure, and each of the two partial shields being radially between said mid-potential shield and one of the two contacts, said shields being fixed at a point of the enclosure without any electrical connection with either of the contacts, wherein the distance between said mid-potential shield and each of the contacts is between 25% and 40% of the axial distance between the contacts, in order to cause an electric field present at the edge of each contact to extend to one of the partial shields or from a partial shield to one of the contacts depending on the polarity of the voltage.