| 摘要 |
PURPOSE:To ensure the communication at sections other than a faulty section by allowing a semiconductor device including a Zener diode provided at the branching point device to form a ground line if an open line fault takes place between a branch point and a station 1 or 2. CONSTITUTION:A positive current is fed from a station 9 and a negative current is fed from a station 10 normally to activate repeaters 13, 14. If an open line fault takes place at a point 20, a voltage at the branch point device 5 rises, a Zener diode array 18 is conducted to form a feeding line. Thus, the communication between the station 9 and the station 11 or 12 is ensured. A breakdown voltage at Zener diode arrays 18, 19 is set to a voltage over a branch point voltage at one end feeding without any fault and a voltage less than the operating voltage of a voltage limit circuit having the drooping characteristic at the feeding side. Further, in order to apply the system to a bipolar feeding voltage, a Zener diode of an opposite polarity is connected in series.
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