Skip to content

The KPIs explained

A KPI (key performance indicator) is a single number a sensor computes from a raw measurement to summarise a machine's condition. You see KPIs as trends in Condition and as the subject of most events. This page explains what the common ones mean and what a rising value tends to indicate.

Vibration KPIs

KPI What it is A rising value often means
Velocity RMS The overall energy of the vibration velocity signal. The primary indicator for most rotating machinery, and the basis of ISO limits. General deterioration — imbalance, misalignment, looseness, bearing wear.
Acceleration RMS The overall energy of the acceleration signal; emphasises higher-frequency content. Early-stage bearing or gear problems, which show up at high frequency first.
Peak-to-peak (P2P) The full swing from the most negative to most positive value in a measurement. Impacts and shocks — looseness, hitting, severe defects.
Zero-to-peak (Z2P) The largest deviation from zero. Similar to P2P; peak severity of the signal.
Kurtosis A statistical measure of "spikiness" — how impulsive the signal is. Impacting faults such as early bearing defects, which add sharp spikes before overall levels rise.
Crest factor The ratio of peak to RMS — how peaky the signal is relative to its average energy. Developing impulsive faults; a high crest factor with normal RMS is an early-warning pattern.
RPM Rotational speed, derived from the magnetic-field signal (given a pole-pair count). Not a fault indicator itself, but the running speed that spectrum peaks are read against.

Vibration KPIs are computed per axis (X, Y, Z) where the sensor measures multiple axes, because the direction of a problem is itself diagnostic (e.g. misalignment often shows axially). The axis directions follow the sensor's orientation on the machine:

The X, Y and Z measurement axes relative to a motor

Which KPIs your machines have depends on the sensor

Treon Industrial Node X (Treon Make) captures triaxial vibration and computes the full set above, plus magnetic field for electric-motor diagnostics. Treon Industrial Node C (Treon Flow) is a KPI sensor that reports velocity RMS and acceleration RMS with temperature. See Overview of solutions.

Temperature

Surface temperature trends complement vibration: rising temperature can indicate friction, lubrication problems, or electrical faults, and often corroborates a vibration trend.

Reading a KPI trend

You watch KPIs as trends on a measurement point's Trends (KPI) tab in Condition. Pick the KPIs and a time range; where a class is assigned, its Warning and Alert limits are drawn on the chart so you can see how much headroom a machine has.

The Trends (KPI) tab: velocity RMS, temperature and magnetic field RMS over 30 days, with per-axis values on hover

  • The trend matters more than the absolute number. A steadily rising KPI on a previously flat machine is a signal even before it crosses a limit — which is exactly what AI anomaly detection is built to catch.
  • Compare a machine to its own history and to similar machines (Comparison).
  • To find the cause behind a rising KPI, drop into the spectrum and waveform.