CHANGE-OVER METHOD FOR CYCLE OF VARIABLE-SPEED MOTOR BY INVERTER

摘要

PURPOSE:To prevent temporary drops in motor speeds, by a method wherein when a plurality of motors are to be changed over from a high-speed running state on a commercial power source to a low-speed running state on an inverter power source, said change-over is effected with time intervals. CONSTITUTION:A dust-collecting equipment comprises a plurality of motors 1a and 1b, blowers 2a and 2b, for example, driven by the respective motors, dust collectors 3a and 3b, for example, and dust-collecting dampers 4a, 4b.... When the motors 1a and 1b are to be changed over from the high-speed running state on a commercial power source to the low-speed running state on an inverter power source through a free running state according to the dust-rising characteristics, said change-over is effected with time intervals as shown in the figures A and B. Thereby, it is made possible to prevent temporary drops in the motor speeds due to the lag of the control system and a large drop in the dust-collecting capacity resulting therefrom.