Motor Current Signature Analysis for the Compound Fault Diagnosis of Reciprocating Compressors

Induction motors as a primer driver, are the most widely electric component in the industry which consume tremendous energy each year. The influence of stator winding asymmetry combined with discharge valve leakage (DVL) significantly increases the temperature and reduces the motor efficiency and shorten the motor life. Monitoring the condition of these machines and their downstream equipment on time not only provides valuable information about the machine conditions but also maintaining their efficiency, avoids severe damage to systems and excessive energy consumption. This paper studies the use of motor current signals information to detect and diagnose the effect of the stator winding on different common reciprocating compressor (RC) faults which create varying load to the induction motor. The motor is applied by the RC with an oscillator torque which induces additional components in measured current signals. Moreover, the current signatures contain changes with the torque profiles due to different types of faults. Based on these analytical studies, the experimental studies examine different common RC faults, such as valve leakage, intercooler leakage, stator asymmetries and the compounds of them. The envelope analysis of current signals allows accurate demodulation of the torque profiles and thereby it can be combined with overall current levels for implementing model-based detections and diagnosis. The results show these simulated faults can be separated under all operating pressures.