A remotely controllable circuit breaker includes main contacts, secondary contacts and an arc plate drawing an arc from a fixed main contact when an operating mechanism opens the main contacts. This configuration allows a user to pull the operating cord a predetermined distance to raise the window shade, then release the operating cord until it has retracted, and then pull the operating cord another predetermined distance to raise the window shade again. The duct is configured to receive an oscillating water column from the body of water wherein oscillations of the oscillating water column generate a fluid flow for driving an energy extraction module. Further, a luminance information obtainment unit obtains luminance information about each of the spectral estimation image signals for obtaining luminance information that have been generated at a predetermined time interval, and obtains a rate of change in the luminance information.