Machine fault detection using vibration signal peak detector

Abstract

A signal processing device for processing a machine vibration signal includes a peak value detector for determining the peak vibration amplitude values during predetermined sample time periods. In one embodiment, the vibration signal is digitally processed prior to receipt by a digital peak value detector. In another embodiment, analog processing and peak value detection of the vibration signal is employed. The peak values are then made available for further processing. In many situations, the peak values will be associated with mechanical faults which will be detected at periodic rates corresponding to the mechanical component defect frequencies without additional signal enhancement. Further enhancement can be acquired by synchronous averaging the peak values with the speed of a rotating element. A signal representing the speed of a rotating element (target element) may be obtained directly from a speed sensor that is measuring the speed of the target element, or if the target element is inaccessible, a corrected pseudo-speed signal can be calculated from the speed of an accessible rotating element that is linked to the target element. Transformation of synchronous amplitudes to the frequency domain by means of a fast Fourier transform reveals information that can be used to assess whether or not a fault is present in the rotating machine element.