1, the choice of sensitivity
The sensitivity of the sensor can be selected with reference to the following ranges: the vibration of the civil engineering prototype and the super large mechanical structure is about 0.1g~10g, and the accelerometer of 3000pC/g~300pC/g can be selected. The vibration of the mechanical equipment is about 10g~100g, and the vibration can be selected. Accelerometers from 20pC/g to 200pC/g can be used for accelerometers from 0.1pC/g to 20pC/g.
2, frequency selection
The frequency response curve given by the manufacturer is screw-mounted and generally divides the curve into two segments: the resonant frequency and the frequency of use. The value of the use frequency is given by the sensitivity deviation, which is ±10%, ±5%, ±3dB. The resonant frequency is generally avoided, but there are also special cases, such as bearing fault detection.
The frequency of the accelerometer should be higher than the vibration frequency of the measured object, and the accelerometer frequency response required by the multiplier analysis is higher. Civil engineering is low frequency, accelerometer can choose 0.2Hz ~ 1kHz or so, mechanical equipment is generally in the middle frequency band, according to equipment speed, equipment stiffness and other factors to comprehensively estimate the frequency, choose 0.5Hz ~ 5kHz accelerometer. Shock measurement is mostly high frequency. Accelerometer's weight, sensitivity and frequency of use are inversely proportional, high sensitivity, heavy weight, low frequency of use, which is also the choice of skills.
3. Internal structure
The internal structure refers to the way of sensing the vibration of the crystal piece of sensitive material and the installation form. There are two types of compression and shearing. Commonly, there are central compression, plane shear, triangular shear and ring shear. The central compression frequency response is higher than the shear type, and the shear type environmental adaptability is better than the central compression type. If the integral type charge amplifier is used to measure the speed and displacement, it is better to use a shear type product, so that the obtained signal has small fluctuation and good stability.
4, built-in circuit
The built-in concept is to place a charge/voltage conversion amplifier circuit in the accelerometer to become a sensing element with a voltage output function. It can be divided into two power supplies (four wires) and a single power source (two wires with offset ICP).
