Abstract: In an electric power device and a method for controlling the same, a first circuit is electrically connected to a first battery tray and a second battery tray, a second circuit is electrically connected to the first battery tray, and a third circuit is electrically connected to the second battery tray. Between the first circuit and the second circuit, a first resistor unit is connected in series with the first battery tray, and a first interrupting unit is connected in parallel with the first resistor unit. Between the first circuit and the third circuit, a second resistor unit is connected in series with the second battery tray, and a second interrupting unit is connected in parallel with the second resistor unit.

Abstract: A roots blower includes driving and driven rotors that rotate while intermeshing with each other, driving and driven shafts fixed at the shaft centers of the driving and driven rotors, respectively, a driving gear attached to the end of the driving shaft, a driven gear that is attached to the end of the driven shaft and intermeshes with the driving gear, a rotor chamber that houses the driving and driven rotors, a gear chamber that houses the driving and driven gears, and driving and driven bearings that rotatably support the driving and driven shafts, respectively. The driving and driven gears are lubricated by a grease.