Determining machine operating conditioning based on severity of vibration spectra deviation from an acceptable state

摘要

The operational condition of a machine is evaluated when the machine's vibration spectrum deviates from an acceptable state, where an acceptable state is defined by an alarm limit envelope. The amplitude of individual peaks within the machine's vibration spectrum is compared to the alarm limit envelope, and a deviation severity value characterizing the severity of the machine's deviation from an acceptable state is determined for each deviating peak. The deviation severity value represents the severity of deviation when at least one individual peak within the machine's vibration spectrum exceeds the alarm limit envelope. The deviation severity value is obtained by determining the peak excess magnitude for each vibration peak, where the peak excess magnitude is the amount by which the amplitude of each deviating vibration peak exceeds the alarm limit envelope level. The peak excess magnitude is then normalized by a frequency-dependent normalization factor. The ratio of the peak excess magnitude to the alarm limit envelope level for each vibration peak is determined. The deviation severity value for the spectral feature under analysis is then determined by selecting the larger of the severity value based on the excess magnitude and the severity value based on the excess ratio. The deviation severity of individual peaks as well as complex features within machine vibration spectra, such as individual peaks and families of harmonic and sideband peaks, may be determined as well to provide information concerning individual fault conditions.