Patent GB-391857-A (GB)
Title: Improvements in automatic or semi-automatic telephone systems
IPC: H04Q1/26
Filed: 1931-11-06
Abstract: 391,857. Automatic exchange systems. STANDARD TELEPHONES & CABLES, Ltd., Connaught House, Aldwych, London. -(Assignees of Materiel Telephonique Soc. Anon. ; 46, Quai de Boulogne, Boulogne, France.) Nov. 6, 1931, No. 30766. Convention date, Dec. 19, 1930. [Class 40 (iv).] A fault at any one of a number of unattended exchanges is signalled by impulses to a central exchange in accordance with its urgent or non- urgent character, and impulses representing the identity of the exchange and the character of the fault are transmitted over a special junction to the main exchange and control an indicator thereat. A modification is referred to in which a separate junction to the main exchange corresponding to each unattended exchange is provided. Alternatively, means for indicating the faults may be brought into operation at the central exchange when an attendant is present. Faults at the central exchange control a fault circuit similar to that associated with each incoming junction allotted for fault signalling. Signalling faults from an unattended exchange, Fig. 1, to the central exchange, Fig. 2. Non-urgent faults cause the operation of relay Pr, while urgent faults cause that of relay Ir. In either case relay A energizes and connects up relay H provided the junction allotted for fault signalling is idle ; otherwise relay B energizes and prevents the operation of relay H. Battery and ground are connected to the junction wires to energize relay Jb at the central exchange, while relays Ac; Ai pull up in turn, and relay Ac falls back, thus transmitting an impulse by removing ground momentarily from the b wire. If the fault is non- urgent, relay Ai locks until relay Al controlled by a thermostat Th operates. Relay Al locks until the fault is cleared and opens the energizing circuit of relay Ac. If the fault is urgent, the locking circuit of relay Ai is opened by relay Ir, and relays Ac, Ai interact to send further impulses until relay Al operates. Signalling faults from the central exchange, Fig. 2, to the main exchange, Fig. 3. Relay Jb connects up relay Jr, and, at the first impulse received from the unattended exchange, relay Ac. energizes due to the removal of a shortcircuit and looks. Relay B energizes provided the junction to the main exchange is idle (otherwise it is short-circuited by relay Cb), connecting up relay St and connecting the junction wires respectively to ground and to battery over the interrupter contact of the magnet Csm. Relay St connects an interrupter to the magnet Csm to drive the switch until the position marked over a contact of relay Ac is reached, when relays T, C operate and lock. At the main exchange, relay Ss energizes and connects up relays Lb, Ct, and impulses due to the stepping of the magnet Csm are repeated to the magnet Msm to step the corresponding switch in synchronism. Series relay I then falls back and closes a circuit for relay R, and the appropriate one of the relays In over wiper b. Relay F, Fig. 2, energizes over the junction and the switches Csm, Msm move automatically to position 8, whereupon relays Of, Cf, Fig. 3, energize in turn, sending an impulse to advance the switches Csm, Msm to position 9, relay F being released. Relay O, Fig. 2, energizes, transferring the incoming junction to relay S, while relay T falls back, reconnecting the junction circuit to the interrupter contact of the magnet Csm. If the fault is non-urgent, no further impulses are received and relay Fo energizes, releasing relay St to restore the switch Csm and opening the junction circuit to restore the switch Msm by releasing relays Ss, Lb, Ct. The operated relay In remains locked and lights the corresponding one of a series of lamps L1, L2, L3. If the fault is urgent, relay S relapses in response to a further impulse and the switches Csm, Msm step to position 10, relay Srl being operated to delay the energization of relay Fo for an interval. Relay Pc, Fig. 3, therefore energizes and locks, causing the lamp lighted by relay In to flash. Recording further faults. In position 10 of the switch Msm, relays Oc, Ho energize and transfer the wires from bank b to the relays Inl, which control the lamps L1, L2, L3 if a further fault signal is received. The operation of any one of these relays connects up relay Oh, and a third fault signal energizes relay Oa which lights a lamp OAL. After actuation of the key RK to cancel the previous indications, the third fault may be recorded on the lamps L1, L2, L3.