PURPOSE:To make electric power installations easier to operate and handle by providing manual switches which are preferential to preset time schedules. CONSTITUTION:The operating and stopping times of plural electric power installations 2-n are concentratedly controlled according to the preset time schedules by a centralized control device 1. Switches which are manually operated are provided to this device 1. When these switches are operated, the installations 2-n are controlled in preference to the preset time schedules. When the switches are released, the installations 2-n are controlled according to the preset schedules.