Free Engineering Tool #023
Vibration Limits — Hydro Turbines & Pump Units
Evaluate vibration severity for hydraulic turbines, pump-turbines, and pumps per ISO 20816-5. Supports bearing housing velocity and shaft displacement measurements.
Results
| Zone | Boundary | Description |
|---|
ISO 20816-5 Scope
ISO 20816-5 specifies vibration evaluation criteria for hydraulic machines including Kaplan, Francis, and Pelton turbines, pump-turbines, and pumps used in hydroelectric power plants. It covers both vertical and horizontal machine configurations.
Bearing Housing Vibration — Vertical Machines
Broadband vibration velocity measured on the bearing housing in mm/s RMS, typically 10–1000 Hz range. Applies to vertical Kaplan, Francis, pump-turbine, and pump units. The zone boundary values on this page are simplified guideline values from the ISO 10816/20816 series; the machine-group- and speed-specific tables of ISO 20816-5 differ in detail and should be consulted for contractual or acceptance evaluations.
| Zone Boundary | Velocity (mm/s RMS) |
|---|---|
| A/B | 2.8 |
| B/C | 5.3 |
| C/D | 8.5 |
Bearing Housing Vibration — Horizontal Pelton
Horizontal Pelton turbines have lower allowable limits due to the bearing arrangement and impulse loading characteristics.
| Zone Boundary | Velocity (mm/s RMS) |
|---|---|
| A/B | 2.3 |
| B/C | 4.5 |
| C/D | 7.1 |
Shaft Displacement — Vertical Machines
Shaft relative displacement is measured with proximity probes, expressed as peak-to-peak displacement in μm.
| Zone Boundary | Displacement (μm p-p) |
|---|---|
| A/B | 80 |
| B/C | 160 |
| C/D | 260 |
ℹ️ Note: Vertical hydro machines have unique vibration characteristics due to gravity acting along the shaft axis. Thrust bearing condition and hydraulic forces (draft tube surge, cavitation) significantly affect vibration behavior.
⚠️ Important: Both bearing housing and shaft vibration should be monitored. The worse of the two assessments governs the overall evaluation. Operating conditions (load, head, tailwater level) strongly influence vibration levels in hydro machines.
ISO 20816-5 applies to hydraulic machines including:
- Vertical Kaplan turbines
- Vertical Francis turbines
- Vertical pump-turbines (reversible)
- Horizontal Pelton turbines
- Vertical pumps
These machines operate in hydroelectric power plants with typical speeds from 60 to 1000 RPM.
Hydraulic machines operate at much lower speeds (60–500 RPM vs 1500–3600 RPM for steam turbines) and experience unique hydraulic excitation forces:
- Draft tube surge and pressure pulsations
- Cavitation-induced vibration
- Wicket gate and runner vane pass frequencies
- Von Kármán vortex shedding
Vertical machines also have additional considerations for thrust bearing vibration and axial hydraulic forces.
Shaft displacement is measured using proximity probes mounted near the guide bearings, measuring peak-to-peak displacement in micrometers (μm p-p). This is critical for vertical machines where shaft orbit monitoring reveals:
- Unbalance and misalignment
- Hydraulic instabilities
- Guide bearing wear
- Seal rub conditions
Horizontal Pelton turbines have lower vibration limits than vertical machines because:
- Horizontal bearing arrangements are more sensitive to dynamic forces
- Impulse loading from the Pelton bucket jet impact produces distinct vibration
- Gravity loads on horizontal bearings create different dynamic behavior
The Zone A/B boundary is 2.3 mm/s vs 2.8 mm/s for vertical machines.
For Zone C on a hydro turbine:
- Investigate root causes: runner cavitation, draft tube surge, guide bearing wear, shaft misalignment, hydraulic resonance
- Increase monitoring frequency to continuous if not already
- Consider load restrictions to reduce hydraulic excitation
- Plan corrective action during the next scheduled outage
- Monitor trend carefully — if approaching Zone D, consider shutdown
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 vibration analyzers and field balancing systems for hydroelectric machinery. ISO 20816 compliant evaluation on-site. 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.
