Development of Electrical Runout Online Measurement System Based on Eddy Current Technique and Laser Triangulation

Material electromagnetic muldistribution of large rotors poses a potential hazard to the operation of rotary machine and interferes the vibration monitoring. These variations of electromagnetic property of material are scaled as electrical runout, which is necessary to be controlled in manufacturing process. A method of offsetting transducer difference for detecting electrical runout online is presented in this paper through finite element analysis, and the corresponding measurement system is developed for large air compressor rotors. A beam of laser with triangulation method is used to measure the surface position of the revolving rotor, which can be transformed as the non-contact distance. In the condition of static sensor probe, rotating centerline and rotary measured points on surface, actual runout of rotor is calculated through signal obtained from laser triangulation measurement. In this way, eddy current sensor, which is posed in the same plane of measuring cross profile with laser device, detects both actual runout and electrical runout as output of total indicated runout. Analyzing two signals through adjusting the phases of cross profile and offsetting the actual runout, electrical runout can be indicated in the process of lathe working. This measurement capability is useful in predicting the vibration level in the slow roll testing before product delivery. At last, the measuring experiment is performed to verify the accuracy of the system