What is sensor sensitivity?

Sensor sensitivity is the ratio of electrical output to mechanical input. For accelerometers, it's typically expressed in mV/g (e.g., 100 mV/g). For velocity sensors, mV/(mm/s) or mV/(in/s). Higher sensitivity means larger output signal for the same vibration level.

How do I choose the right sensitivity?

Higher sensitivity (e.g., 500 mV/g) gives better signal-to-noise ratio for low-level vibration but limits the maximum measurable level. Lower sensitivity (e.g., 10 mV/g) is needed for high-g measurements. Match sensitivity to expected vibration levels and DAQ input range.

What is the dynamic range of a sensor?

Dynamic range is the ratio between the maximum measurable signal and the noise floor, usually expressed in dB. For IEPE sensors, max output is typically ±5V peak. Dynamic range = 20×log10(Vmax/Vnoise).

What is IEPE (ICP) sensor powering?

IEPE (Integrated Electronics Piezo-Electric) sensors require constant-current excitation (typically 2-20 mA) at 18-30V DC bias. The AC vibration signal rides on top of the DC bias. ICP is a trademark of PCB Piezotronics for IEPE technology.

Can I use a voltage divider to match sensor output to my DAQ?

Yes, but it reduces signal-to-noise ratio. Better approaches: use a sensor with appropriate sensitivity, adjust DAQ input range, or use a signal conditioner with programmable gain.

免費工程工具 — #017

振動感測器靈敏度計算器

根據靈敏度與振動級別計算感測器輸出信號電壓。確定 IEPE 加速規與速度感測器的動態範圍與最大可測振幅。

加速規速度感測器mV/g · mV/(mm/s)

結果

輸出信號電壓

—

最大可測級別

—

輸出佔滿量程百分比

—

動態範圍

—

信號級別 (dBV)

—

輸出信號電壓

最大可測級別

常見感測器類型

類型	典型靈敏度	範圍	頻率範圍
一般 IEPE 加速規	100 mV/g	±50 g	0.5–10 kHz
低頻加速規	500–1000 mV/g	±5 g	0.1–1 kHz
衝擊加速規	1–10 mV/g	±500–5000 g	1–20 kHz
速度感測器	4–20 mV/(mm/s)	0.1–100 mm/s	1–1 kHz

範例 — 標準加速規

已知： 靈敏度 = 100 mV/g，振動 = 5 g pk，最大輸出 = 5 V pk

V_輸出 = 100 × 5 / 1000 = 0.500 V 峰值

最大級別 = 5000 / 100 = 50 g 峰值

輸出 = 0.5 / 5 × 100 = 滿量程的 10%

⚠️ 注意： 超過最大輸出電壓會導致信號削波，進而產生失真。務必確認預期振動級別保持在感測器範圍內。