| 摘要 |
PURPOSE:To couple safely a signal externally to a conductor in an underwater cable even during operation by separating a high-voltage circuit section from an external low-voltage circuit section by means of an optical fiber cable in the detection of an open cable of the underwater cable. CONSTITUTION:A low-frequency output light signal of a low-frequency optical oscillator 18 mounted externally connected to an optical connector 17 provided at a position having a chassis potential of a cable anchor frame 3 propagates through an optical fiber 16 and reaches a photodiode 15. The input light to the diode 15 causes the impedance of the diode 15 to be changed, thereby forming an input signal to a transistor (TR) 20. This input signal is amplified and its output appears between terminals 12 and 13 and is coupled to a conductor 2'. The low-frequency signal of the low-frequency optical oscillator 18 becomes an electric signal each having identical waveform and is coupled into the conductor 2' of the cable. |
