Air flow controlling apparatus.

摘要

An airflow controlling apparatusforaccomplishing blasting with a desired airflow by controlling an electric motor for a ventilator for feeding airfor combustion to a boiler as well as a damper located in an air course. In order to control a temporary increase or decrease of an air flow due to a variation of a rotational frequency of the electric motor when power supply to the electric motor is changed over between a commercial power source and a variable frequency power source, the apparatus includes a preceding controlling signal generating means which regulates the opening of the damperfor a period of time from a point of time at which a power source changing over instruction is received to another point of time at which an actual changing over operation is performed.