Centrally-controlled telephone exchange - locates de-centralised faults and sends alarm signals to replacement and central control units

摘要

The telephone exchange indicates faults by releasing alarm signals which prevent the exchange's continued operation being affected by failures. Additional devices are connected to the decentralised control units as peripheral devices arranged in groups. Separate signal circuits are also connected to the decentralised control units. The additional devices and the signal circuits pass alarm signals via an alarm line to the reserve device that locates the fault. Alarm signals can be sent to the replacement unit and to the central control unit via the shared alarm line to which all signal circuits are connected.