Electrical signature analysis (ESA) developments at the Oak Ridge Diagnostics Applied Research Center

Since 1985, researchers at the Oak Ridge National Laboratory (ORNL) have developed and patented several novel signal conditioning and signature analysis methods that have exploited the intrinsic abilities of conventional electric motors and generators to act as transducers. By using simple nonintrusive sensors such as clamp-on current and voltage probes, these new diagnostic techniques provide an improved means of detecting small time-dependent load and speed variations generated anywhere within an electromechanical system and converting them into revealing signatures that can be used to detect equipment degradation and incipient failures. These developments have been grouped under the general name of electrical signature analysis (ESA) and together provide a breakthrough in the ability to detect, analyze, and correct unwanted changes in process conditions or the presence of abnormalities in electrical and electromechanical equipment. Typical diagnostic information provided by ESA is comparable to that provided by conventional vibration analysis in that both time waveform and frequency spectrum signatures may be produced. The primary benefit of ESA is that an extensive range of diagnostic information can be obtained from a single transducer that may be installed several hundred feet or more from the monitored device on its electrical lines supplying input power (e.g., to a motor) or carrying output power (e.g., from a generator); thus, ESA is truly remote and nonintrusive.