EQUIPMENT MONITORING METHOD, EQUIPMENT MONITORING SYSTEM AND EQUIPMENT MONITORING APPARATUS

PROBLEM TO BE SOLVED: To realize a technique for remote monitoring that is low in power consumption and high in reliability. SOLUTION: A first and a second optical channel 5 and 6 are laid between a monitoring site 2 and a monitored site 3. In the monitored site 3, signal light transmitted through the first optical channel 5 is incident on an optical splitter 31, signal light output from the optical splitter 31 is partly incident on a photoelectric transducer 33 and partly incident on an optical switch 32 for controlling outgoing light in dependence on an external input voltage, the output voltage of the photoelectric transducer 33 is inputted as the input voltage after control depending on the state of monitored equipment, and the outgoing light of the optical switch 32 is incident on the second optical channel 6. The monitoring site 2 monitors the signal light transmitted through the second optical channel 6 to monitor the state of the monitored equipment 4. COPYRIGHT: (C)2005,JPO&NCIPI