Comparative Evaluation of 500 mV/g Accelerometers

Comparative Evaluation of 500 mV/g Accelerometers: Experimental Measurements of Frequency Response and Immunity to Interference

Foreword

Whether it is online monitoring of industrial equipment or modal mechanical testing in a laboratory, the frequency response stability and electromagnetic interference immunity of vibration sensors directly determine the long-term operational accuracy and reliability of the entire monitoring system.

I. Description of the Test Plan

1. Comparison Samples:

This laboratory conducted a side-by-side comparison of piezoelectric accelerometers with the same specifications. Both products—a sensor developed in-house by Xiyuan Electronics and a product from a leading domestic brand—have a nominal sensitivity of 500 mV/g. Throughout the testing process, the calibration bench, data logger, and EMC interference equipment were standardized, and installation, power supply, and accompanying cables were kept consistent to eliminate interference from external variables. Quantitative testing was conducted across four key dimensions: full-band frequency response, 4 kV EFT (electrical fast transient), close-range walkie-talkie RF interference, and static background noise. The performance differences between the two products were objectively demonstrated using actual raw waveforms and data, providing a reliable reference for sensor selection.

2. Four Core Test Items

Frequency response testing: Covers the full frequency range from 0.2 Hz to 10 kHz to verify the stability of measurement errors at both high and low frequencies;

EFT (Electrical Fast Transient) immunity: ±4000 V, industrial standard interference level;

Close-range RF interference test: Simulate on-site communication interference with the walkie-talkie’s distance sensor set to ≤10 cm;

Static background noise test: Collect baseline noise in a rigidly fixed environment free from external vibrations.

II. Interpretation of Itemized Measurement Data

(1) Frequency Response Testing: Balanced high- and low-frequency response, with more stable error control in the high-frequency range

The test consists of sweep data acquisition in the low-frequency range (0.2–160 Hz) and the high-frequency range (160–10,000 Hz), with amplitude errors calculated using 160 Hz as the reference.

Comparison of Low-Frequency Response Test Data

Both products meet the general monitoring standard of 0.5 Hz ± 1 dB; under ultra-low-speed conditions of 0.2 Hz, Xiyuan sensors maintain a more stable amplitude error, making them better suited for ultra-low-frequency micro-vibration scenarios such as rotating equipment, bridges, and tower shells.

Comparison of High-Frequency Response Test Data

A comparison of the full-frequency error curves at 8 kHz, 9 kHz, and 10 kHz shows that the competitor’s error at 8 kHz is nearly 9.47%, and at 10 kHz, it reaches 17.43%; in contrast, Xiyuan’s sensors keep the error at 8 kHz within 5%, and at 9 kHz, they still meet the ±1 dB performance standard, with even lower amplitude drift across the entire high-frequency range. Under high-frequency operating conditions—such as gear meshing, high-speed spindles, and impact testing—Xiyuan sensors exhibit lower signal distortion and provide a more complete reproduction of fault characteristic signals.

(2) ±4000 V EFT Pulse Immunity Test

Test Method:

The EFT generator was set to output an interference signal at a frequency of 5 kHz, and testing was conducted by applying a voltage of ±4000 V. After the voltage was applied, the acceleration waveform was recorded using a data logger.

EFT Test Curve for a Domestic Sensor

Xiyuan Sensor EFT Test Curve

In industrial settings, the start-stop operations of variable frequency drives and contactors generate large bursts of pulse interference, which can easily cause data fluctuations and false alarms. When subjected to the same 4 kV EFT interference, the comparison sample’s output waveform exhibited a significant step-like surge with a peak exceeding the measurement range, followed by sustained, chaotic spikes after the pulse—conditions that are likely to trigger false system alarms; Xiyuan sensors exhibit only transient, narrow pulse spikes, with no baseline shift and no sustained step-like interference; the waveform rapidly returns to zero once the interference ceases, ensuring greater long-term operational stability in workshops with dense electronic control systems and in the vicinity of variable-frequency equipment.

(3) Close-Range Radio Frequency Interference Testing of Two-Way Radios

Interference-Resistant Waveform of a Domestic Sensor Walkie-Talkie

Xiyuan Sensor Walkie-Talkie Interference-Resistant Waveform

On-site patrol walkie-talkies operating at close range are the most common source of radio frequency interference. In this test, a walkie-talkie was placed within 10 cm of the sensor and continuously transmitted a signal. When subjected to interference, the output amplitude of the competitor’s product exceeded the measurement range, resulting in prolonged, chaotic, and saturated waveforms. The interference lasted for 8 seconds; after the signal returned to normal, the baseline exhibited a prolonged negative drift and took several seconds to return to zero; When interfered with, the Xiyuan sensor maintains a stable amplitude within ±15 mV, with no saturation or step changes. The interference duration is shorter, and the baseline recovers instantly once the signal is removed, with no residual drift. It is suitable for factory environments with multiple inspectors and a high density of wireless devices.

(4) Static Background Noise Test

Test Method:

1. Mount the sensors on a rigid mounting block, connect them to the same data acquisition system, collect raw acceleration data in a stationary state, and compare and analyze the results from the two sensors.

2. Keep the vibration table turned off during the test to minimize the influence of external vibrations, and use the data logger to record time-domain waveforms.

Time-domain waveform of a domestic sensor

Xiyuan Sensor Time-Domain Waveforms

Baseline noise was tested in a completely stationary, rigidly fixed environment free from external vibrations: The static background noise of the comparison sample was approximately 98 μV, while that of the Xiyuan sensor was approximately 52 μV. Although there is a slight difference in the overall noise values, this difference does not affect routine vibration monitoring of industrial equipment. For ultra-low-level micro-vibration testing scenarios, Xiyuan can provide custom low-noise sensors to meet the requirements for high-precision, low-level data acquisition.

III. Summary of Comprehensive Field Tests

Based on the results of four standardized laboratory tests, the two 500 mV/g sensors each have their own strengths:

Xiyuan Sensors' Core Advantages

① The overall frequency response is more balanced, with better performance in the ultra-low-frequency range and outstanding amplitude stability in the 8 kHz to 9 kHz high-frequency range, making it suitable for both low-speed equipment and high-speed impact scenarios;

② It demonstrates outstanding immunity to two typical industrial interference sources—EFT pulses and near-field RF—with no baseline steps, no signal saturation, and no zero-point drift, significantly reducing the probability of false alarms in the field;

③ The integrated isolation circuit design is suited for complex electromagnetic environments, ensuring better data consistency during long-term online monitoring.

Xiyuan products offer lower static background noise levels, providing certain advantages for capturing extremely faint static signals.

IV. Recommendations for Model Selection and Compatibility

Xiyuan sensors are the preferred choice for the following applications: wind turbines, gearboxes, high-speed spindles, variable-frequency drive units, plant environments with multiple wireless devices, low-frequency modal testing of bridges and large structural components, and long-term unattended online monitoring;

For research applications involving faint static micro-vibrations, low-noise sensor versions can be customized upon request.

Conclusion

Yangzhou Xiyuan Electronics specializes in the research, development, and production of piezoelectric vibration sensors. All products undergo comprehensive testing for frequency response, noise, and EMC immunity before leaving the factory, and performance calibration is conducted in our in-house calibration laboratory. This comparative analysis is based solely on objective, laboratory-measured data and is intended to provide a reliable reference for equipment maintenance and scientific research professionals when selecting products. We are continuously optimizing our circuitry and sensor designs to develop highly stable, interference-resistant vibration measurement solutions made in China.

Yangzhou Xiyuan Electronic Technology Co.,Ltd.

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