How to select industrial sensors
Veröffentlichte Zeit: 2020-02-10 22:38:21
The selection of industrial sensors is very important, if the selection is not appropriate for the sensor measurement is a great impact. How to choose the sensor reasonably according to the specific measuring purpose, measuring object and measuring environment?
1. Determine the type of sensor according to the measurement object and measurement environment
In order to carry out a specific measurement, the first thing to consider is the principle of the sensor, which can only be determined after analyzing various factors.Because, even if the measurement of the same physical quantity, there are also a variety of principle of the sensor available for selection, which principle of the sensor is more appropriate, we need to consider the following specific problems according to the characteristics of the measurement and the use of the sensor: the size of the range;Requirement of sensor volume for measured position;The measurement method is contact type or non-contact type;Signal derivation method, wire or non-contact measurement;The source of sensor, domestic or import, price can bear, or self-developed.
After considering the above problems, we can determine which type of sensor to choose and then consider the specific performance indicators of the sensor.
2. Sensitivity selection
Generally, within the linear range of the sensor, the higher the sensitivity of the sensor is expected to be, the better.Because only when the sensitivity is high, the value of the output signal corresponding to the measured change is relatively large, which is conducive to signal processing.However, it should be noted that the sensitivity of the sensor is high, and the external noise irrelevant to the measurement is easy to mix in, which will also be amplified by the amplification system, affecting the measurement accuracy.Therefore, it is required that the sensor itself should have a high signal-to-noise ratio to minimize interference signals from outside.
The sensitivity of the sensor is directional.When the measurement is a single vector and the direction of the sensor is high, the sensor with low sensitivity in other directions should be selected.If it is measured as a multidimensional vector, the less cross sensitivity of the sensor is required, the better.
3. Frequency response characteristics
The frequency response characteristics of the sensor determine the frequency range to be measured and must be kept undistorted within the allowable frequency range.In fact, the response of the sensor always has a constant delay. The shorter the delay, the better.
The higher the frequency response of the sensor, the wider the frequency range of the signal can be measured.
In dynamic measurement, response characteristics (steady-state, transient, random, etc.) should be taken into account to avoid excessive errors.
4. Linear range
The linear range of the sensor is the range in which the output is proportional to the input.In theory, the sensitivity remains constant in this range.The wider the linear range of the sensor, the larger the measuring range and the higher the measurement accuracy.When selecting a sensor, after the type of sensor is determined, the first thing to look at is whether the range meets the requirements.
But in fact, no sensor can guarantee absolute linearity, and its linearity is also relative.When the required measurement accuracy is relatively low, the sensor with small nonlinear error can be regarded as linear in a certain range, which will bring great convenience to the measurement.
The ability of a sensor to maintain the same performance over a period of time is called stability.Besides the structure of the sensor, the main factor affecting the long-term stability of the sensor is the environment in which the sensor is used.Therefore, to make the sensor have good stability, the sensor must have strong environmental adaptability.
Before selecting a sensor, it is necessary to investigate its use environment, select the appropriate sensor according to the specific use environment, or take appropriate measures to reduce the impact of the environment.
The stability of the sensor has a quantitative index. After the expiration of the service life, the sensor should be calibrated again before use to determine whether the performance of the sensor has changed.
In some occasions where sensors can be used for a long period of time and cannot be easily replaced or calibrated, the stability of the selected sensors is more stringent and can withstand the test of a long time.
Precision is an important performance index of sensor, and it is an important link related to the measurement accuracy of the whole measurement system.The higher the precision of the sensor, the more expensive it is. Therefore, as long as the accuracy of the sensor can meet the requirements of the whole measurement system, it is not necessary to choose too high.In this way, it is possible to choose the relatively cheap and simple sensor atlas air compressor accessories from a variety of sensors for the same measurement purpose.
If the purpose of measurement is qualitative analysis, choose the sensor with high repetition precision, not the sensor with high absolute value precision;If it is for quantitative analysis, it is necessary to obtain accurate measurement value, we need to choose the sensor whose accuracy level can meet the requirements.
For some special use occasions, unable to choose the appropriate sensor, it is necessary to design and manufacture the sensor.The performance of the self-made sensor should meet the service requirements.Etikett: sensors