| 摘要 |
PROBLEM TO BE SOLVED: To provide a fault detection circuit that surely transmits SCN information to an exchange control system in the case of a fault contact of AC power supply and a subscriber line. SOLUTION: In the 2-wire subscriber circuit that transmits a fault state such as an AC contact with a subscriber line or the like superimposed on an SCN signal to an exchange control system, an over-voltage detection circuit 4 that outputs over-voltage information S4 when being applied with the voltage higher than an each level of a feed circuit 2 is provided on the side of a subscriber line L1, an over-voltage detection circuit 3 that outputs over-voltage detection information S3 when being applied with the voltage lower than a feeding circuit power supply voltage L1 is provided on the side of a subscriber line L2, and an over-voltage information storage circuit 6 that stores the sum information of the respective over-voltage detection information for a prescribed time is provided. Then the output of the storage circuit 6 is superimposed on the SCN signal and the resulting signal is sent to an exchange. |
