| 摘要 |
PURPOSE:To detect the rotational speed of an AC rotary machine without attaching any rotational speed detector to the rotary shaft by detecting the rotational speed based on the vibration frequency of the AC rotary machine and the frequency of its power source or power generation. CONSTITUTION:A switch SW is closed and a motor 1 is driven. The vibration frequency generated by the motor 1 is detected by a vibration detector 8 from which vibration detection signal is supplied to the rotational speed detector 10 through a vibration signal cable 3. The frequency of the power source is detected by a frequency detection part 9 from which frequency signal is supplied to a rotational speed computing element 10. The rotational speed computing element 10 performs operation based upon the inputted vibration frequency and the frequency of the power source to calculate the rotational speed and supplies its output signal to a display device 5 through an output signal cable 6.
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