| 摘要 |
PURPOSE:To prevent the stoppage of a cooling fan even under a strong wind by detecting wind velocity having an effect on the revolving torque of the cooling fan and changing the number of revolution of the cooling fan on the basis of the change of the wind velocity. CONSTITUTION:Wind velocity having an effect on a cooling fan 2 is detected by an anemometer 10, and the detecting signal is transmitted over a controller 8. Wind velocity at that time and the revolving torque of the cooling fan 2 operated by output frequency at that time are compared in the controller 8. When the revolving torque of the cooling fan 2 is smaller than wind velocity, a changeover signal 11 is transmitted, a switch 5 is changed over automatically to OFF and a switch 4 to ON, and operation is changed over to commercial frequency power supply direct-coupled operation. |
