| 摘要 |
PURPOSE:To detect the abnormality in a flow passage accurately by determining the deviation between the fluid pressure obtained from the speed of an electric motor and the fluid pressure obtained from the torque of the motor. CONSTITUTION:A blower pump 3 or the like for passing fluid from A0 to A1 is driven by means of an AC electric motor 2 which is controlled in speed by an AC variable speed driver 7. The driver 7 is varied in speed according to the speed signal (n) of a speed setter 8. A speed signal (v) is inputted to an abnormality detecting circuit 9 by the signal T for detecting the motor torque from the driver 7. In the circuit 9, a standard fluid pressure H is determined according to Hinfinity n<2> and an actual fluid pressure H' is determined according to H'infinity T. The deviation between these fluid pressures and the deviation in the permissible fluid pressure at the speed signal (n) are compared, and an abnormal pressure signal 106 is generated, whereby the abnormality is detected at a constant detection level in the abnormality of the flow passage. |
