| Paper description |
In industrial production process, rotational speed is a key parameter for equipment condition monitoring and fault diagnose. To achieve rotational speed measurement of a certain type of rotational equipment under a condition of high temperature, heavy dust, this article proposes a digital approach using an electrostatic sensor. The proposed method utilizes a strip of a predetermined material stuck on the rotational shaft which will accumulate charges because of the relative motion with the air. Then an electrostatic sensor mounted nearby the strip is employed to obtain the fluctuation signal related to the rotation of the charged strip. Via a certain signal conversion circuits, a square wave the frequency of which equals to that of rotation shaft can be obtained. Having the square wave, M/T method and T method are utilized to find out the rotational speed. Experiments were conducted on a laboratory-scale test rig to compare the proposed method with auto-correlation method. The biggest relative errors of auto-correlation method with the sampling rate of 2ksps, 5ksps are 3.2%, 1.3% respectively. The relative errors using digital approach are both within ±4‰. The linearity of the digital approach combined with M/T method or T method is also superior to that of auto-correlation method. Performance of standard deviations and response speed also was compared and analyzed to show the priority of digital approach. |
(创新港)
