Patent ID: 6965672

Claim:
An electronic switching system for connecting electronically a common source of voltage (Ue) to a chosen user station selected from a plurality of user stations connected in parallel; the system comprising a plurality of identical cells equal to the number of user stations, each cell corresponding to one user station, wherein each cell comprises a first electronic device for rectification of alternating and direct line current through the cell and for electronic separation of a ground of said each cell from respective grounds of other ones of said cells, a second electronic device to connect a respective corresponding user station to the common source of voltage, and a device for providing an automatic blocking command comprising a plurality of optical photo couplers each associated with one of the cells not corresponding to the chosen user to maintain separation of the different grounds of the cells and to control blocking of electronic connection of user stations other than the chosen station to the common source of voltage, whereby upon connection of the chosen user station to the common source of voltage, flow of restored continuous current through the photodiodes in the cell corresponding to the chosen station saturates corresponding phototransistors located in cells not corresponding to the chosen user station which in turn block ballast transistors located in said cells not corresponding to the chosen user station, thereby blocking the connection of user stations other than the chosen station to the common voltage source.