Portable power unit

摘要

A portable power unit has a protective circuit for cutting off an output current from the power unit when the power unit is in an overload state. An amount of the output current is detected. An output voltage from the power unit is reduced when the amount of the output current detected reaches a first threshold value, thereby preventing the protective circuit from undesirably operating for one power unit when it is connected for another for parallel operation. When the amount of the output current decreases to a second threshold value which is smaller than the first threshold value, with the power unit being in a state in which the output voltage is reduced, the voltage-reducing operation is canceled.