GB149816A - Improvements in automatic telephone systems - Google Patents

Abstract

149,816. Relay Automatic Telephone Co., and Johnson, B. B. June 13, 1919. Addition to 112,650. Automatic and semi-automatic exchange systems.-A line on becoming faulty prepares circuits so that when it is called a faulttone is given to a subscriber or a lamp-flashing signal to an operator. When a line A becomes faulty, its line relay L is energized and causes one of the switching-relays C to connect it, in known manner, to an idle junction line, the relay C locking up in a circuit 3 including the cut-off relav CO and a fault relay F. The impulse relay IR of the selected junction is energized over the faulty line, and after an interval, determined by a timing-device T, opens the circuit 3. The relay F, being slow to de-energize, locks up over a circuit 5 including the faulty line, but the cut-off relay CO is de-energized. When a line A in normal condition is called, one of the relays C is energized over the marking lead 66 and locks up over circuit 3. When the line becomes faulty, the lead 66 is extended over the front contact of relay F and the back contact of relay CO to the relay R6 (or R11) of an idle fault-indicating unit. When the faulty line is called, the relay R6 (or R11) is energized over circuit 6 (or 11) and a relay R7 is energized over circuit 7 to connect the calling-line to the fault tone circuit 8. The relay R7 locks up over a circuit 9 energizing relays F9, C09 which extend the circuit 6 to the relay R11 &c. of a second faultindicating unit. The fault tone set includes an interrupter so as to give a flashing signal to a calling operator. In a modification, the fault tone set is associated with each of the trunks to which a calling line is connected at the pre-digit stage. A switch may be provided whereby a faulty line may be connected either to the fault tone set or to a fault test disk or manual operator.