A branching unit integrated into a
submarine telecommunication
system comprising three cables having optical and electrical transmission members comprises three terminals connected to the electrical transmission members of the cables, three input points, and three
electrical contacts each between one of the terminals and one of the input points. In an operating configuration, and at a given time, a first terminal and a second terminal are electrically connected together and form a
trunk segment adapted to convey a
trunk current, and a third terminal is electrically connected to a
submarine ground to form a
branch segment adapted to convey a
branch current. The branching unit carries out reconfiguration by controlling switching of the
electrical contacts. A
voltage indicating the potential at a point on the
trunk segment is measured. Because an optical reconfiguration request is made by means of an optical reconfiguration
signal the unit is able to receive and process optical reconfiguration signals. Reconfiguration is validated according to the measured
voltage and to the signals received and processed and reconfiguration in accordance with the optical reconfiguration
signal is activated only if the absolute value of the potential is below a threshold.