The Actuator Fault Diagnosis Based on the Valve Friction

Control valve (actuator) is the frequently moving terminal Instrument of the control system. To avoid the leaking of the actuator, there is packing at the moving parts. However, the friction caused by the packing can do harm to the control of the system. The washing effect of the media, high temperature, high pressure, frequent movement and other effects can result in the leaking of the packing and the deformation of the valve stem, which causes the change of the friction. The study of the control of the friction has always been an interesting topic in the industry. In this paper, we theoretically analyze the relationship of the friction of the packing and the static performance of the control valve, and offer a method to check the quality of the moving parts by attaching a strain gage (strain rosette) to the empty part of the valve stem. This method has been demonstrated via experiment and a method to do error detection is provided at last

On-line Detection of the Change of Friction in Control Valve

The function of stuffing box in pneumatic control valve is dynamic seal, but it also produces friction. The friction will affect the performance of position control. This paper proposes a method, based on the error integral indexes of control loop. On-line detection of the change of friction in control valve can use this method. Firstly, we use TOPSIS method to choose the appropriate error integral index. And then using the appropriate index describes the change of friction. The results found that, the relevance between the change of friction in control valve and the error integral of control loop is existing

The Diagnosis of Internal Leakage of Control Valve Based on the Grey Correlation Analysis Method

Abstract: The valve plays an important part in the industrial automation system. Whether it operates normally or not relates with the quality of the products directly while its faults are relatively common because of bad working conditions. And the internal leakage is one of the common faults. Consequently, this paper sets up the experimental platform to make the valve in different working condition and collect relevant data online. Then, diagnose the internal leakage of the valve by using the grey correlation analysis method. The results show that this method can not only diagnose the internal leakage of valve accurately, but also distinguish fault degree quantitatively. Copyright © 2014 IFSA Publishing, S. L