How to correctly select the appropriate vibration sensor

The vibration sensor mainly monitors the vibration of rotating machinery. Each equipment has its own vibration standard. Exceeding the vibration value indicates that the machine has a fault, so the vibration sensor plays a role in protecting the vibration.

There are two types of vibration sensors: magnetoelectric type and piezoelectric type. The magnetoelectric type has simple structure, low price, but poor accuracy. Now the piezoelectric type sensor is commonly used, with high measurement accuracy. The vibration sensor first senses the vibration acceleration, obtains the velocity through integration, and obtains the displacement through secondary integration, but the acceleration and displacement will be affected by the frequency, At the same time, the vibration standard is called vibration intensity, which is the effective value of vibration speed. Therefore, the vibration speed is usually monitored.

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Selection guide and evaluation standard of vibration sensor

In order to select an ideal vibration sensor, the following three aspects of the test object (signal) must be analyzed and evaluated

2. Frequency range of vibration signal

3. Environment of vibration test site

According to the analysis results of the above three aspects, the type selection can be carried out with reference to the relevant technical indicators of the sensor

1) Selection of sensitivity and measurement range of vibration sensor

The estimation of vibration will help to determine the sensitivity, measurement range, resolution and other relevant indicators of the sensor. The measurement range refers to the amount of * * * that the sensor can measure*** The large measurement value is usually associated with the allowable non-linear error. The measurement range of voltage output accelerometer is equal to the ratio of sensor output * * * large signal voltage to sensitivity.

The measured value usually depends on the electrical noise of the measurement system. The main source of the electrical noise of the low resistance voltage output accelerometer is the electrical noise of the built-in circuit of the sensor. Therefore, the small measured value is the ratio of the electrical noise of the sensor to the sensitivity. It must be pointed out that the electrical noise of general sensors refers to its voltage effective value in a wide frequency band, while the electrical noise at each frequency point is of more practical significance in the frequency domain analysis of vibration signals. Especially for the measurement and analysis of low-frequency signal, because the acceleration signal is relatively weak and the electrical noise increases, it is particularly important to understand the electrical noise at the actual measurement frequency.

The selection of sensitivity after measurement should be as high as possible when the external size and frequency range are small.

2) Selection of measurement frequency range of vibration sensor

The measurement frequency range of vibration sensor refers to the frequency range with a certain sensitivity deviation based on the sensitivity of the specified frequency point. The sensitivity deviation is generally \ and can be divided into ± 5% ± 10% ± 3dB. As a general rule, the vibration sensor with high sensitivity has low cut-off frequency at high frequency and heavy weight. On the contrary, the sensor with wide measurement frequency range has small volume and light weight, but low sensitivity.

It must be pointed out that the measurement range of the vibration sensor is closely related to the installation mode. The use frequency range of the vibration sensor should be matched with the appropriate installation mode. If the measurement frequency range of the vibration sensor is too high, it will not only be difficult to install in the actual use process, but also greatly increase the cost of the vibration sensor.

Post time: Feb-24-2022