| 摘要 |
PURPOSE:To prevent not only the parts destruction at each section, but also a fault from spreading to another line, by detecting an abnormal voltage generated when system power supply short-circuits with the circuit of another power supply voltage by means of an abnormal voltage detection circuit and cutting off a feeder circuit from the output side by means of a relay contact. CONSTITUTION:When system power supply gets into a subscriber line, a reverse current I2 flows from the subscriber line through the circuit 13 of a circuit package. Simultaneously, a contact rl1 opens at an abnormal voltage detection circuit 14. Therefore, a feeder circuit is protected by interrupting the reverse current I2 flowing into the feeder circuit from the system power supply short- circuited with the subscriber line and the occurrence of parts destruction, etc., is prevented at the feeder circuit. |
