Power supply system for toyohashi cabled observatory with wide input-range

A new cabled observatory off Toyohashi in central Japan is now being developed. In this area, mega-thrust earthquakes are anticipated, and continuous longterm monitoring is needed to promote seismic study and to mitigate disasters. It will use a pair of decommissioned underwater optical telecommunication cables of 60 kilometers in length. A new junction box will be deployed at the end of the cable which will be equipped with five underwater mateable connectors. The cables will also be used to electromagnetically study the inner structure of crust. In order to use the cable as a low-frequency emitting antenna, the authors developed a new power supply system in which supply voltage/current can be widely controlled. This paper will describe the outline of the observatory and the power supply system.