| 摘要 |
PURPOSE:To detect the cause of a fault easily and to fix the charge of responsibility on repairs precisely by separating a subscriber's private device from a subscriber's line terminal by a remote operation from a testing board. CONSTITUTION:When 100V DC voltage e.g. is impressed between a defective line and the earth for several seconds from the central office side, a capacitor 17 is charged through diodes 11, 12, 14. When a power supply is turned off on the central office side, a transistor (TR) 13 is turned on and relays 15, 16 are actuated, so that a corresponding relay contact is actuated and the subscriber's private device is separated from the line. Consequently, the relay 15 is restored after about 15sec and then relay contacts 151, 152 are restored, opening the line. Subsequently, the relay 16 with lower opening voltage is restored after about 10sec and relay contacts 161, 162 are restored, so that the subscriber's private device is connected to the line to return to the normal state. |
