Measurement of Phased Data

Measurement of Phased Data

Why It Matters:

The most important and well estab­lished technique for machine monitor­ing is vibration analysis. However, not all vibration analyses are the same. Seemingly minor differences in data acquisition and evaluation strategies can have a dramatic impact on the quality of signal diagnoses. Choosing the proper mathematical evaluation method is the key to reliable early fail­ure detection and safety protection.

The Best Approach:

First, monitoring systems should con­tinuously acquire and diagnose machine vibrations for each crank revolution and then segment signals into crank-angle-related portions. This allows harmless, but sometimes erratic, machine behav­ior to be rightly identified as a “good condition” – thereby avoiding false alarms. PROGNOST Systems invented segmented vibration analysis in the late 1990´s and has since determined that the best approach is to subdivide the 360° of one revolution into 36 segments

of 10° crank angle each. This is the most accurate proportion of an average im­pact width related to one revolution.

Second, vibration signals must be evaluated using the most accurate mathematical analysis. For reciprocating machinery, only RMS (Root Mean Square) analysis is proven reliable. RMS analysis is superior because it considers not only amplitude, but also the energy content of an impact.