Abstract: The stations (S1to SN) are interconnected in series by a ring (A), and the system of the invention includes a spare ring (AS) interconnecting the stations in series, together with two self-healing circuits (CAM, CAV) in each station coupler (CS) between the two connectors (8, 9) of the coupler and its insertion relay (RI). The couplers are interconnected by cords (10; 11) each containing the ring (A), the spare ring (AS), and two detection links (12, 13). Each self-healing circuit includes a relay (6) and a relay control circuit (7) connected to a detection link whose other end is connected to ground in another self-healing circuit. Each relay (6) has fixed contacts (a1, a2, b1, b2), a first moving contact (C1) connected to the insertion relay (RI), and a second moving contact (C2). The second moving contacts (C2) of the two self-healing circuits (CAM, CAV) in the same coupler are interconnected by a spare link (L).