System for supplying current surge in installations for telecommunications and in particular in installations for telephony, a central control unit

摘要

In centrally controlled telephone switching systems in which junction circuits (VSI1-VSIx) of the same type are divided into groups (GI) and all the junction circuits are supplied by a ringing current generator (REI), the supply is taken over by a second ringing current generator if a failure occurs. Considerable circuit and wiring cost is required to safeguard the ringing current supply. This is avoided by permanently allocating a single ringing current generator in each case to each group (GI) of junction circuits (VSI1-VSIx), by marking all the junction circuits (VSI1-VSIx) of this group (GI) as defective if a ringing current generator (REI) fails and then by forwarding an incoming request to a free junction circuit of a different group (GII). IMAGE