What does ISO 20816-21 cover?

ISO 20816-21 specifies vibration evaluation criteria for onshore and offshore wind turbines. It covers the main drivetrain components: main bearing, gearbox, generator, and tower top (nacelle) vibration. It addresses both velocity and acceleration measurements depending on the component and frequency range of interest.

Why are different measurement types used for different components?

Velocity (mm/s RMS) is used for gearbox, generator, and tower top measurements where the dominant vibration frequencies are in the typical 10-1000 Hz range. Acceleration (g RMS) is used for main bearings where low-speed, high-frequency bearing defect signals are better captured by accelerometers, particularly for the slow-rotating main shaft (typically 10-20 RPM).

How does turbine power class affect vibration limits?

Larger turbines (>3 MW) generally have lower rotational speeds and higher structural flexibility, which can influence vibration behavior. However, the zone boundaries in ISO 20816-21 are generally consistent across power classes, as they are based on component-level severity rather than overall turbine size. The power class context helps with interpretation.

What is tower top vibration and why monitor it?

Tower top (nacelle) vibration reflects the overall structural response of the wind turbine to aerodynamic loads, rotor imbalance, and drivetrain forces. Excessive tower top vibration can indicate rotor mass or aerodynamic imbalance, yaw misalignment, foundation issues, or structural resonance. It is typically measured in mm/s RMS.

What should I do if wind turbine vibration reaches Zone C?

Zone C indicates the component is not suitable for continuous long-term operation. Actions include: investigate root cause using CMS (condition monitoring system) data, review SCADA trends for correlation with wind speed and power, check for bearing damage using envelope analysis, inspect gearbox oil for metal particles, consider curtailing the turbine until corrective action is completed, and schedule maintenance during the next suitable weather window.

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振動限值 — 風力渦輪機

依據 ISO 20816-21 評估風力渦輪機組件的振動嚴重度。支援主軸承、變速箱、發電機及機艙頂部量測。

ISO 20816-21 A/B/C/D 區風力渦輪機

結果

振動區

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測量值

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建議

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ℹ️ 組件註記：

公差帶	邊界	說明

ISO 20816-21 範圍

ISO 20816-21 規範了陸上與離岸風力渦輪機的振動評估準則。涵蓋主要動力傳輸組件及塔架/機艙結構，並針對風能系統的獨特運轉條件進行評估。

變速箱 — 速度（mm/s RMS）

變速箱振動係於軸承座使用速度感測器進行量測。多級齒輪會產生複雜的振動特徵。

區域邊界	振速 (mm/s RMS)
A/B	3.5
B/C	7.1
C/D	11.2

發電機 — 速度（mm/s RMS）

發電機的振動限值較低，因為發電機屬於公差要求較嚴格的精密旋轉機械。

區域邊界	振速 (mm/s RMS)
A/B	2.8
B/C	5.6
C/D	9.0

主軸承 — 加速度（g RMS）

主軸承以極低轉速運轉（10–20 RPM）。加速度量測可捕捉速度感測器會遺漏的高頻軸承缺陷訊號。

區域邊界	振動加速度 (g RMS)
A/B	0.5
B/C	1.0
C/D	2.0

機艙頂部（機艙） — 速度（mm/s RMS）

機艙頂部振動反映了整體結構對空氣動力負荷及動力傳輸力的響應。

區域邊界	振速 (mm/s RMS)
A/B	2.0
B/C	4.0
C/D	7.0

ℹ️ 注意： 風力渦輪機振動隨風況變化極大。量測應在一致的運轉條件下進行（例如額定功率、特定風速區間），以進行有意義的比較。CMS（狀態監測系統）可提供持續追蹤。

⚠️ 重要： 主軸承故障是風力渦輪機維修成本最高的項目之一。透過振動監測（特別是高頻加速度與包絡分析）進行早期偵測，對於在災難性故障發生前進行計畫性更換至關重要。