Velocity Rms
Velocity RMS (VRMS) is the Root Mean Square of a vibration velocity signal, representing the effective energy level of mechanical vibration in rotating machinery. It is calculated by squaring each sample, averaging the squares, and taking the square root, yielding a single value in mm/s that correlates directly with component fatigue and wear.
In CMMS/Asset Reliability systems like ServiceGrid, VRMS is the primary parameter for assessing machinery vibration severity per ISO 20816. It is used to trend machine health in the 10–1000 Hz range, trigger alarms based on ISO Zones A–D, and drive condition-based maintenance decisions weeks before failure. This allows shop floor maintenance teams to prioritize interventions and prevent unplanned downtime.
Why use velocity over displacement or acceleration for vibration monitoring?
Velocity tracks fatigue-causing energy more consistently across industrial speeds because damage severity is fairly constant across a wide frequency band for velocity.
What is the formula for VRMS for a pure sine wave?
For a pure sine wave, VRMS = 0.7071 × peak amplitude.
How are alarm thresholds set for VRMS?
Alarm thresholds are typically set at 3× baseline RMS for Alert and 6× baseline for Danger, or using ISO 20816 severity zones (e.g., Zone B/C limit for rigid support Group 2 is 2.8 mm/s).