Experiences of FRA measurements on Medium Voltage Rotating Machines

Frequency Response Analysis (FRA) test is a widely used tool for diagnosing the internal condition of transformers during preventive maintenance, after transport or after through-faults. Currently the technique is being investigated for its application in motors and generators, but most of the experimental applications have been oriented to measurements in low voltage machines. In this paper, experimental measurements of FRA test made in different medium voltage rotating machines are presented. The objective is to show typical responses of healthy and damaged machines, and to indicate some external factors that can influence the results.