Chapter 27 - Transient (Waterfall) Analysis

Abstract

Transient analysis (TA) is a common application of real-time analysis (RTA). The most popular method of TA, waterfall analysis, captures a series of closely timed signatures to evaluate the transient. Most real-time analyzers provide the ability to capture and display a variety of waterfall or multiple-spectra plots that facilitate transient diagnostics. The setup procedures for this type of analysis may vary, depending on the type of instrument used. The information required by the set-up includes input group, load-control group, load method, and number of records. Pseudo-waterfall analysis can be conducted with some general-purpose vibration instruments. However, the real-time analyzer's combination of parallel multichannel signals and fast data-processing time makes it an excellent diagnostic tool. The diagnostic logic used to perform waterfall analysis is identical to that used in frequency-domain analysis. The only true difference is in the quality and timing of the data that are used. RTA uses data that are acquired as the event happens. As a result, there is typically much more data, but its total time span is relatively short