Methods and systems for automatic rolling-element bearing fault detection

A system (100) capable of automatically detecting a rolling-element bearing (106) fault in a rotating machine (101) is provided. The system (100) receives, from at least one sensor (110), a sensor signal that includes at least one frequency and converts the sensor signal to a digital vibration signal. The system (100) modifies the vibration signal to generate an envelope signal and applies a transform to the enveloped signal to generate an envelope spectrum. The system (100) uses certain relationships among envelope spectral line amplitudes and their harmonics to detect bearing faults. As such, the system (100) detects a bearing fault without reference to predefined fault frequencies.