Free Engineering Tool
Vibration Measurement Plan Generator
Calculate recommended frequency range, measurement points, acquisition time, and data storage. Generate a downloadable measurement plan.
Measurement Plan
Maximum Frequency (Fmax) Recommendation
Fmax must capture the highest-frequency defect of interest. For rolling element bearings, the outer race defect frequency (BPFO) is approximately:
To capture 3rd harmonic of BPFO with sidebands, the recommended Fmax is:
Frequency Resolution & Acquisition Time
The frequency resolution determines the minimum resolvable frequency difference:
The time record length T (acquisition time for one average) equals 1/Δf. With 4 averages (75% overlap), total acquisition time ≈ 1.75 × T.
Data Storage Calculation
Each spectrum stores amplitude values for every FFT line. Storage per measurement:
Measurement Directions
| Direction | Code | Detects |
|---|---|---|
| Horizontal | H | Unbalance, looseness, misalignment |
| Vertical | V | Unbalance, bearing defects |
| Axial | A | Misalignment, thrust bearing, blade pass |
Practical Example
Shaft frequency: f = 2960/60 = 49.3 Hz
BPFO estimate (12 rollers): 0.4 × 12 × 49.3 = 236.8 Hz
Fmax: 3.5 × 236.8 = 828 Hz → round to 1000 Hz
Points: 4 bearings × 3 directions = 12 points
Δf (800 lines): 1000/800 = 1.25 Hz → can resolve 1× at 49.3 Hz easily
Storage: 12 × 3 params × 800 × 4 = 115,200 bytes ≈ 113 KB
⚠️ Note: For gearbox vibration analysis, Fmax should cover gear mesh frequency and its harmonics: GMF = N_teeth × shaft_speed. This calculator focuses on rolling element bearing machines.
Fmax should be at least 3.5× the highest bearing defect frequency (BPFO). For rolling element bearings, BPFO ≈ 0.4 × N × RPM/60 where N is the number of rolling elements. This calculator uses the higher of BPFO-based and machine-type-based Fmax recommendations.
Common Fmax values: 1000 Hz for standard machines, 5000 Hz for high-speed, 10000+ Hz for turbines.
FFT lines determine frequency resolution (Δf = Fmax / lines):
- 400 lines — Fast screening, walk-around routes
- 800 lines — Routine monitoring (most common)
- 1600 lines — Detailed analysis, gear mesh
- 3200 lines — High-resolution bearing analysis
- 6400 lines — Maximum resolution for close frequencies
Velocity (mm/s RMS, 10–1000 Hz): Overall machine condition per ISO 10816. Best for 600–60000 RPM machines.
Acceleration (g peak): Bearing defects, gear mesh, high-frequency problems.
Displacement (μm pk-pk): Low-speed machines below 600 RPM.
Envelope: Early bearing defect detection via demodulation of high-frequency resonances.
Minimum: 2 per bearing (Horizontal + Vertical). Recommended: 3 per bearing (H + V + Axial). The axial direction is essential for detecting misalignment, thrust bearing wear, and blade/vane pass issues.
For critical machines, add extra points on gearbox housings or at shaft seals.
Each FFT spectrum stores one float32 (4 bytes) per line. Formula: Storage = Points × Parameters × FFT_Lines × 4 bytes. Example: 12 points × 3 params × 800 lines × 4 = 115,200 bytes ≈ 113 KB per machine.
A full route of 50 machines typically requires 2–10 MB of storage.
The procedures described on this page were developed and field-tested by the Vibromera team using the Balanset-1A, a portable dual-channel balancer and vibration analyzer for on-site rotor balancing.
Professional field balancing instruments and vibration analyzers. Used in 50+ countries.
Nikolai Shelkovenko
Nikolai Shelkovenko is a vibration analysis engineer and the founder and CEO of Vibromera. For more than 15 years he has balanced rotating equipment in the field rather than on a test bench: mulchers, industrial fans, crushers, centrifuges, shafts and spindles. That work is what the Balanset instruments grew out of — they were designed as a tool a specialist can carry to the machine and use alone, on site, not as laboratory equipment. Vibromera was founded in 2017 and has been based in Porto, Portugal, since 2023. Development, assembly and support of the Balanset line all happen here. The flagship instrument is the Balanset-1A, a portable analyser for single- and two-plane balancing and for vibration diagnostics. Nikolai is personally involved in customer support, in working through difficult balancing cases and in the development of the software. He works with customers worldwide, in any language.
