| 摘要 |
PROBLEM TO BE SOLVED: To operate a fan motor by making a switch to constant r.p.m. control while neglecting the r.p.m. control of an r.p.m. detection means when a signal therefrom can not be detected. SOLUTION: Upon receiving an operation command signal data from a remote controller 31, a microcomputer 46 turns an SRR 33 on in order to turn a fan motor 35. When the SSR 33 is turned on by delivering a pulse having width (b) with a time lag an from the zero-cross point of a full-wave rectified waveform (t), i.e., the falling point of a waveform (u) from H to L, the SSR 33 turns on the tan motor up to the zero-cross point of a waveform (s). The control is repeated and the fan motor 35 is rotated at a speed regulation F1. The microcomputer 46 detects a rectangular wave from an r.p.m. detection element 36 in order to determine rotation of the fan motor 35. More specifically, a decision is made that the tan motor 35 is rotating it the rectangular wave is detected whereas a decision is made that the fan motor 35 is locked it the rectangular wave is not detected for a specified time and then the fan motor 35 is stopped. |
