| 摘要 |
PURPOSE:To detect the power failure of a commercial electric system accurately on a local power generation system side, by changing periodically for a short period of time an electric current to be supplied to a storage battery by a charge controller. CONSTITUTION:A charge controller 6 passes a low current through a storage battery 8 normally and a high current therethrough periodically for a short period of time, when said storage battery 8 is charged almost fully; while said charge controller passes a high current through the storage battery 8 normally and a low current therethrough periodically for a short period of time, when the battery 8 is charged insufficiently. Thus, when power supply is cut OFF in said commercial electric system 10, the balance between the output of an inverter 3 and the whole load is lost and said output of the inverter 3 changes so as to increase or decrease. In this case, said change appears as a change in the voltage or frequency of said inverter 3 so that the power failure of said commercial electric system 10 can be detected accurately when the change in said voltage or frequency is monitored. |
