| 摘要 |
PURPOSE:To continue a normal operation when a controller is defective or a signal line is disconnected by detecting the malfunction of the output signal of the controller, interrupting the output signal of the controller, and continuing the control with a measured value before the malfunction. CONSTITUTION:The output signal of a controller 8 and the output signal of a rotational speed detector 9 are input to a malfunction signal detecting unit 10. The output signal 9a of the rotational speed detector 9 is held, and converted by a converter to an input signal to a rotational speed controller (VVVF) 6. A rate of change inspection and upper and lower limit inspection are executed to judge whether it is normal or not. In case of normal, a contact 11 is closed to be controlled by the controller 8. In case of abnormal, the contact 11 is opened, and the value of the converter is output to the VVVF 6. |
