| 摘要 |
PURPOSE:To detect the surging automatically in its early stage by detecting an oscillation in an orthogonal direction to the rotation axis center of a rotating fluid machine and detecting the frequency of a rectangular pulse which is shaped by taking out an output signal proper to the surging from the output signal. CONSTITUTION:A band-pass filter 4 passes an oscillation frequency component due to the surging, for instance, the 5-20Hz frequency component alone and cuts the others and sends the extracted component to a comparator 6. On the other hand, a threshold level setter 7 generates a 0.5V volt. threshold level SH corresponding to the amplitude generating at the time of regular operation of the rotation axis 1, for instance, the 10mum amplitude and sends it to the comparator 6. Hereby, the comparator 6 takes out only the signal >=0.5V volt. with the 5-20Hz frequency which is shaped to the rectangular pulse and sent to a computing element 8. The computing element 8 calculates the frequency of the rectangular pulse, for instance, whether an interval of the rectangular pulse is within one second or not and outputs it. It is decided that the surging is taking place when two rectangular pulses are outputted within one second.
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