What is vibration phase angle?

Phase angle describes the timing relationship between a vibration signal and a reference. It is measured in degrees (0–360°) and indicates where in the rotation cycle the peak vibration occurs. Phase is critical for balancing and diagnosing machine faults.

How do I measure phase angle?

Phase is measured using a tachometer (keyphasor) as a reference, combined with a vibration sensor. The phase angle is the angular difference between the tachometer pulse and the peak of the 1× vibration signal.

What is the vector sum of two vibration signals?

The vector sum combines two vibration signals (each with amplitude and phase) into a single resultant vector. It uses the formula: add the x-components and y-components separately, then calculate the resultant amplitude and phase.

Why is relative phase important in balancing?

In single-plane balancing, the phase shift between the original vibration and the trial-weight run indicates the angular correction needed. A 180° phase shift means the correction weight should be placed opposite to the trial weight.

What does 0° vs 180° phase mean?

0° phase between two measurement points means the points move in the same direction simultaneously (in-phase, common with unbalance). 180° means they move in opposite directions (out-of-phase, typical of misalignment or a rotor operating above its critical speed).

免費工程工具 — #018

振動相位角計算器

計算兩個振動信號的相對相位、向量和與向量差。輸入每個信號的振幅與相位。

向量和向量差相對相位

結果

相對相位角

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向量和（振幅）

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向量和（相位）

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向量差（振幅）

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向量差（相位）

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向量表示

每個振動信號皆為向量 V = A∠φ，其笛卡爾分量為：

向量和與差

相對相位

兩個信號之間的相對相位角：

實務範例

範例 — 動平衡校正運轉比較

信號 1： 5.2 ∠45° → x₁ = 3.677, y₁ = 3.677

信號 2： 3.8 ∠200° → x₂ = −3.571, y₂ = −1.300

向量差： Δx = 7.248, Δy = 4.977 → |ΔV| = 8.79 ∠34.4°

相對相位： |200° − 45°| = 155°

ℹ️ 提示： 在單平面動平衡校正中，原始運轉與試重運轉之間的向量差代表試重單獨產生的效應。