Vibration Classroom, Issue 7

Calibration and maintenance of piezoelectric vibration sensors

In the fields of industrial automation, equipment status monitoring, and fault diagnosis, piezoelectric vibration sensors can be regarded as the "stethoscope" for equipment health. It is widely used in mining, metallurgy, wind power, rail transit, and intelligent manufacturing due to its advantages of high sensitivity, wide frequency response, and strong anti-interference.

But many users only focus on "use" and ignore "calibration" and "maintenance" - data drift, sensitivity attenuation, increased signal noise, irregular jumps... The root cause of the vast majority of measurement anomalies lies in calibration deficiencies and improper maintenance.

Today, Yangzhou Xiyuan Electronics deeply analyzes the calibration and maintenance system of piezoelectric vibration sensors from principles, standards, methods, cycles, troubleshooting to daily maintenance, helping you achieve long-term stable, accurate and reliable vibration measurement.

1.frequently asked questions

Q1: How to determine the calibration cycle of acceleration sensors?

A: It is recommended that the initial calibration cycle be 1 year. If the temperature fluctuation in the working environment is greater than 20 ℃ or the humidity is greater than 80%, it should be shortened to 6 months.

Q2: How to determine if the sensor needs to be recalibrated?

A: Calibration is required when the measurement data exhibits the following characteristics:

Continuous drift of zero output value>1% FS

The standard deviation of repeated measurement results under the same operating conditions is greater than 3%

The frequency response curve drops by more than 1dB in key frequency bands (such as 100Hz-1kHz)

Q3: Can the sensor be cleaned by oneself during maintenance?

A: You can use a dust-free cloth dipped in isopropanol to gently wipe the outer shell, but it is forbidden to use ultrasonic cleaning or high-pressure air guns to avoid damaging the internal structure.

Q4: What factors may cause abnormal fluctuations in sensor output signals?

A: Common reasons include:

Poor cable contact (check if the shielding layer is damaged)

Excessive power ripple (using linear power supply instead of switching power supply)

Mechanical resonance (adjusting sensor installation stiffness)

Q5: How to extend the service life of sensors?

A: Following the principle of "three avoidance":

Avoid long-term use beyond the range (recommended to work within 70% of the range)

Avoid mechanical impact (install shock pads to reduce vibration transmission)

Avoid extreme temperatures (operating temperature range controlled between -20 ℃~+85 ℃)

2.Why is calibration so important?

The core of piezoelectric sensors is piezoelectric crystals, which are subject to long-term effects such as temperature, humidity, mechanical stress, impact, oil pollution, and dust, resulting in:

Sensitivity decrease (most commonly due to crystal aging and charge leakage)

Zero drift (output non-zero when there is no vibration)

Frequency response distortion (loss of high-frequency signals, resonance shift)

Insulation degradation, increased noise (due to moisture and aging of seals)

If not calibrated:

Equipment vibration exceeding the standard is misjudged as normal → sudden shutdown, safety accident

Normal vibration misjudged as abnormal → meaningless shutdown, loss of production capacity

Data analysis distortion, incorrect trend judgment → operational decision-making failure

One sentence: Without calibration, there is no reliable data; Without maintenance, there is no long-term accuracy.

3.Vibration sensor calibration: 159.2Hz

In vibration testing, sensor calibration, and NVH experiments, one frequency has almost become the "industry default standard" -159Hz (more accurately 159.15Hz/159.2Hz). Many people may wonder for the first time: why is it not the integer 100Hz or 200Hz, but this seemingly fragmented value? In fact, this is not a random choice, but the optimal solution that balances mathematical conversion, engineering practicality, and anti-interference.

159.2Hz (theoretical standard value)

Corresponding angular frequency ω=2 π f ≈ 1000 rad/s

At this frequency: acceleration, velocity, and displacement values are equal (e.g. 10 m/s ²=10 mm/s=10 μ m)

Advantages: Simple calculation, error free conversion, intuitive on-site verification

Basis: Recommended reference calibration frequency according to GB/T, JJG, ISO standards

Applicable: on-site calibration, handheld calibrator, internal comparison, operation record

160Hz (engineering convention value)

The rounding approximation at 159.2Hz has an error of only 0.5%, which is acceptable for engineering purposes

Advantages: easy to remember, concise, and universally applicable in the industry

Applicable: Factory certificate, parameter table, safety standard materials, promotional copy

4.Full analysis of mainstream calibration methods (laboratory to site)

1) Absolute method (highest accuracy, metrological level)

Laser interferometry

Principle: Laser vibrometer directly measures vibration displacement/velocity/acceleration, tracing back to wavelength reference

Accuracy: highest, with an uncertainty of up to 0.5%

Usage: National Institute of Metrology, CNAS laboratory, high-end sensor calibration, certificate submission

2)Comparison method (factory standard, king of cost-effectiveness)

Back-to-back comparison method

Operation: The calibrated sensor and the first level standard sensor are rigidly coaxially installed on the vibration table, with the same frequency and vibration

Calculation: Sensitivity=Standard Sensitivity × (Calibrated Output/Standard Output)

Features: Moderate equipment cost, simple operation, high efficiency, and precision that meets industrial standards

Purpose: Factory calibration, batch inspection, daily re inspection, production line consistency control

3)Vibration table calibration (condition based calibration)

Sine sweep frequency calibration

Frequency points: 10Hz, 159.2/160Hz, 1kHz, 5kHz (covering commonly used frequency bands)

Calibration items: sensitivity, amplitude frequency characteristics, linearity, lateral sensitivity

Purpose: Factory inspection, new product validation, performance confirmation after major repairs

Impact calibration

The impact table generates standard pulses (such as 1000g, 0.1ms)

Calibration: impact range, transient response, peak linearity

Usage: Sensors specifically designed for mining, heavy industry, and explosion-proof equipment

4)Quick on-site calibration (workshop/project site)

Portable handheld calibrator

Fixed frequency: 159.2Hz, standard acceleration (e.g. 1g)

One click verification: sensor+cable+collection system overall link

Features: No need for large equipment, 5-minute completion, essential for inspection

Purpose: Daily inspection, troubleshooting, on-site comparison, system verification

5)Environmental calibration (essential for special working conditions)

High and low temperature calibration (-40 ℃~+125 ℃): temperature drift coefficient calibration

Damp Heat Calibration: Insulation and Stability Verification in High Humidity Environments

Explosion proof/mining calibration: Environmental adaptability testing required for safety certification

5.Common Malfunctions and Troubleshooting

Conclusion

The accuracy of piezoelectric vibration sensors is not "once and for all", but "long-term protection". Calibration is the bottom line of accuracy, and maintenance is the guarantee of lifespan. I hope this in-depth analysis can help you establish a systematic awareness of calibration and maintenance, ensuring that every measurement is accurate and reliable, and safeguarding equipment safety and efficient production.

Yangzhou Xiyuan Electronic Technology Co.,Ltd.

#77 Yeqiao Road, Liandong U Valley slender West Lake Innovation port, building 10-2,Hanjiang District, Yangzhou,Jiangsu,China

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