POWER-SUPPLY SYSTEM FOR RAILWAY SIGNALLING DEVICES

摘要

A power-supply system for railway signalling devices wherein an a.c. voltage source (3) supplies by means of a two-wire supply cable (4) a first signalling device (6) of a railway type; a current-controller device (8) is set between the voltage source (3) and an input (4-in) of the supply cable for controlling whether the current absorbed by the first signalling device falls within a safety range. Moreover provided are: a first tuned input filter (10) designed to enable circulation of a harmonic component of the a.c. voltage in the current controller (8); a tuned output filter (12) connected at input to an output terminal (4-out) of the two- wire cable and at output to the first signalling device (6); a rectifier device (14) designed to extract a d.c. component from said a.c. voltage to inject it into the two-wire supply cable downstream of the current controller (8); and a d.c- component-extraction device (16) connected at input to the output terminal (4-out) of the two-wire cable and at output to a power-supply input of a second signalling device of a railway type (20) for supplying with just the d.c. component the second signalling device without modifying the value of the current that circulates through the current controller and that is absorbed by just the first signalling device (6).