When using a pressure sensor, there will inevitably be some problems, such as noise, so why does the noise occur? It may be caused by the discontinuity of the internal conductive particles, or the shot noise generated by the semiconductor device, etc. So in order to reduce the occurrence of these problems, you need to pay attention to some things when using pressure sensors. The following is a detailed introduction, let’s take a look.
Causes of noise in pressure sensor
The pressure sensor has noise during use. What is the reason for the noise? ATO summarizes the reasons for the noise as follows:
- carbon film resistors, there are often many tiny particles inside the carbonaceous material, and the particles are discontinuous. When the current flow expires, the conductivity of the resistor will change and the current will change, resulting in similar contact inconsistencies. Good flashing arc.
- The shot noise generated by semiconductor devices is mainly due to the change of the voltage of the barrier region at both ends of the semiconductor PN junction, which causes the change of the number of charges accumulated in this region, thus showing the capacitance effect. When the forward voltage decreases, it keeps electrons and holes away from the depletion region, which is equivalent to capacitor discharge.
- When the reverse voltage is applied, the change of the depletion region is opposite. When current flows through the barrier region, this change causes small fluctuations in the current flowing through the barrier region, resulting in current noise. Generally, the electromagnetic components on the pressure sensor circuit board, if there is interference, there are electromagnetic components such as relays and coils on many circuit boards. When the electricity is smooth and smooth, the inductance of the coil and the distributed capacitance of the shell radiate energy to the vicinity, and the energy will affect the energy. Nearby circuits are causing interference.
- When components such as relays work repeatedly, instantaneous reverse high voltage will be generated when the power is turned on and off, forming an instantaneous surge current. This instantaneous high voltage will have a large impact on the circuit, thus severely disturbing the normal operation of the circuit.
The precautions for the pressure sensor in daily use are as follows:
- Prevent dross from depositing in the conduit and contact the transmitter with corrosive or overheated media.
- When measuring gas pressure, the pressure taking port should be opened at the top of the process pipeline, and the transmitter should also be installed on the upper part of the process pipeline, so that the accumulated liquid can be easily injected into the process pipeline.
- When measuring the liquid pressure, the pressure tap should be opened on the side of the process pipeline to avoid the deposition of slag.
- The pressure guiding pipe should be installed in a place where the temperature fluctuation is small.
- When measuring the liquid pressure, the installation position of the transmitter should avoid the impact of the liquid (water hammer phenomenon), so as to prevent the sensor from being damaged by overpressure.