Exciting method and voltage of vibrating wire sensor by hand-held vibrating wire acquisition instrument

Sensor excitation method and excitation voltage

incentive ： Also known as “ Excitation ”, It is a necessary process for the frequency data acquisition of vibrating wire sensors , Only when the sensor receives Natural vibration can be generated only after appropriate excitation signal , Only when the vibrating wire sensor produces natural vibration can the frequency signal be output , further , The reading circuit will detect and read the natural vibration signal of the vibrating wire sensor , Can be calculated Vibration frequency value . Excitation signal of vibrating wire sensor （ The external signal that can make the sensor produce natural vibration ） The general points There are two types , One is high voltage short pulse , A class of multiple groups of continuous low-voltage pulse signals with specific frequency .

High voltage pulse excitation ： Use higher voltage （100~200V） Send a short pulse to the coil of the vibrating wire sensor , The process or method of making the vibrating wire sensor of any frequency produce self vibration .

Low voltage sweep excitation ： The use is equivalent to the natural vibration frequency of the sensor （ near ） The frequency of sends a continuous signal to the vibrating wire sensor Low voltage of the （3~10V） Pulse signal , The process or method of making the sensor vibrate naturally .

 

Vibrating wire acquisition instrument provides a variety of vibrating wire sensor excitation methods , To be compatible with more models of vibrating wire sensors . The excitation method parameters of the vibrating wire sensor are located on the right side of the real-time data window , share 5 Two methods are optional , Use them separately MODTH0~MODTH4 Express . Various methods are described below ：

 

The excitation voltage data is displayed on the screen as xxx/xxx In the form of , The front number represents the actual excitation voltage , The following numbers represent the excitation voltage source voltage VSEN. The power supply used for high-voltage pulse excitation and low-voltage sweep frequency excitation methods comes from VSEN, relatively speaking , Use higher VSEN Can get better sensor signal , But some sensors must use lower VSEN Voltage will get stable frequency data . There are two versions of the hand-held vibrating wire collector , When it is necessary to modify the excitation method or excitation voltage source , If there are two rotary switches on the back of the device , Then turn the switch directly ; If there is no rotary switch, you need to use the above operation keys to modify the parameters . The meaning of the gear of the rotary switch of the excitation method is the same as that in the above table , Drive the gear of the voltage rotary switch 0~15 Presentation settings VSEN by 0~15V（ front 5 The gear is fixed to 5V）.

 

Be careful ： Suggest VSEN The voltage of should not exceed 12V, Recommended setting as 5~8V. If VSEN The voltage setting is too high , Measure some small resistance values （ Less than 200 ohm ） There is a risk of damage to the sensor or equipment . In use , Pay attention to observe the vibrating wire signal quality value displayed on the screen , For a certain class or some sensors , Different excitation methods will have a great impact on the signal quality , The switching and use of excitation methods should take the highest signal quality as the selection standard .

Vibrating wire sensor ：（vibrating wire sensor） It is a resonant sensor with a taut metal steel string as the sensing element . When the length of the string is determined , The variation of its natural vibration frequency can characterize the tensile force of the steel string . According to this characteristic principle , Through certain physics （ mechanical ） The structure makes different kinds of measurements Physical quantity like Sensor （ Such as ： Strain sensors 、 Pressure sensor 、 Displacement sensor, etc ）, So as to realize the one-to-one correspondence between the measured physical quantity and the frequency value , Calculate the measured physical quantity by measuring the change of frequency value The amount of change . 

Vibrating wire sensor acquisition reading module ： The pointer excites the sensor designed for the characteristics of the vibrating wire sensor 、 Reading module . It has a high degree of integration 、 Function modularization 、 A series of features of digital interface , Can complete vibrating string Sensor excitation 、 Signal detection 、 Data processing 、 Special targeted functions such as quality evaluation , Conduct sensor frequency Rate and temperature physical quantity analog-to-digital conversion , Then realize data interaction through digital interface . Vibrating wire sensor reading module Vibrating wire sensor and digitalization 、 The core conversion unit between informatization . 

Vibrating wire sensor return signal ： When the sensor generates natural vibration , Steel string self vibration cutting sensor coil , In the online circle Generate weak current , This sinusoidal electric wave that changes with the vibration of the steel string is called “ Vibrating wire sensor return signal ”. 

Sampling value ： Also known as “ A single sample ”, In this manual, especially the single sinusoidal signal returned by the sensor , in order to Improve the measurement accuracy of sine wave frequency value , Multiple groups of sinusoidal signals need to be collected for comprehensive calculation . Because of the sensors The returned sinusoidal signal gradually disappears from strong to weak , And the signal itself is very weak , Vibrating wire sensors from different manufacturers The strength and duration of the return signal are different , Therefore, the vibrating wire module adopts the method of partial sampling to obtain Take some sampling data for comprehensive calculation , For each sine wave collected, it is called “ A sample ” or “ A sample value ”. 

Standard deviation ：（Standard Deviation）, It is also often called mean square deviation in Chinese environment , Is the standard value of each unit of the whole （ Sampling value ） The square root of the difference between the arithmetic mean of its mean . The standard deviation can reflect the deviation of a data set Dispersion degree （ Two sets of data with the same average , Standard deviation may not be the same ）. A large standard deviation , On behalf of most There is a big difference between the score and its average ; A smaller standard deviation , Represents that these values are closer to the average , High quality . 

ADC：（Analog-to-Digital Converter） simulation - Digital converter . It refers to the simulation that will change continuously A device that converts a signal into a discrete digital signal .

VREF：（Voltage reference） It refers to one and load in the circuit 、 Power supply 、 Temperature drift 、 Time It's nothing to do with it , It can maintain a constant voltage . The reference voltage can be used for the voltage regulator of the power supply system , Analog to digital converter and digital to analog converter , And many other measurements 、 Control system .

GPIO：（General Purpose Input Output） Universal input / Output （ Interface ） Or bus extender , In layman's terms , It's just some pins , They can output high and low levels or read the electricity of pins through them Flat state .