Pressure Sensor Working Principle

- Oct 18, 2016-

  • Pressure Sensor Working Principles:

A pressure transducer is a device or device that can sense a pressure signal and can convert a pressure signal to an available output electrical signal in accordance with certain rules.

The pressure sensor is usually composed of a pressure sensitive element and a signal processing unit. According to the different test pressure type, the pressure sensor can be divided into gauge pressure sensor, differential pressure sensor and level pressure sensor.

Liquid level pressure sensor QST-201.jpg

Pressure sensors are the most commonly used sensors in industrial practice. They are widely used in various industrial automation environments, involving water conservancy and hydropower, railway transportation, intelligent building, production control, aerospace, military, petrochemical, oil, electricity,pipelines and many other industries, the following brief introduction to some commonly used sensor principle and its application. Another medical pressure sensor.

QP-82C photo.jpg

  • Wiring method

Sensor wiring has always been the customer procurement process consulting one of the most problems, many customers do not know how to connect the sensor, in fact, a variety of sensor wiring are basically the same, the pressure sensor is generally two-wire, three-wire system, Four-wire system, and some five-wire system.

Pressure sensor two-wire system is relatively simple, the general customers know how wiring, a line to connect the power positive, the other line is the signal line through the instrument connected to the power supply negative, this is the most simple, pressure sensor three-wire system is in two Line system based on the addition of a line, this line directly connected to the negative power supply, more trouble than the two lines. Four-wire pressure sensor is certainly two power input, the other two are signal output. Four-wire system is mostly the output voltage instead of 4 ~ 20mA output, 4 ~ 20mA called the pressure transmitter, the majority made of two-wire system. Pressure sensor signal output is not amplified, full-scale output only tens of millivolts, and some pressure sensor in the internal amplifier circuit, full-scale output of 0 ~ 2V. As for how to receive the display instrument, depending on the instrument range is how much, if there is and the output signal to adapt to the stalls, you can directly measure, or to increase the signal to adjust the circuit. Five-wire pressure sensor and the four-line system is not much difference, the market five-wire sensor is also less.

QP-82B wire connection.png

  • Working Principles:

1, piezoresistive force sensor

The resistance strain gauge is one of the main components of the piezoresistive strain sensor. Metal resistance strain gauge working principle is adsorbed on the matrix material strain resistance with mechanical deformation and resistance to change the phenomenon, commonly known as resistance strain effect.

2, ceramic pressure sensor(QP-83C):

Ceramic pressure sensor based on the piezoresistive effect, the pressure directly on the front surface of the ceramic diaphragm, the diaphragm has a small deformation, thick film resistance printed on the back of the ceramic diaphragm, connected into a Wheatstone bridge, due to varistor The voltage of the bridge is proportional to the pressure, Strain sensors are compatible.

3, the proliferation of silicon pressure sensor:

Diffused silicon pressure sensor is also based on the principle of piezoresistive effect, the use of piezoresistive effect principle, the pressure of the measured medium directly on the sensor diaphragm (stainless steel or ceramic), the diaphragm and the medium pressure is proportional to the micro- So that the resistance of the sensor changes, the use of electronic circuits to detect this change, and convert the output of a corresponding to the pressure of the standard measurement signal.

4, sapphire pressure sensor:

The use of strain resistors working principle, the use of silicon - sapphire as a semiconductor sensor, with unmatched measurement characteristics. Therefore, the use of silicon-sapphire semiconductor-made components sensitive to temperature changes are not sensitive, even in high temperature conditions, but also has a good working characteristics; sapphire anti-radiation characteristics of strong; In addition, silicon - sapphire semiconductor sensor, no pn drift.

5, piezoelectric pressure sensor:

Piezoelectric effect is the main working principle of piezoelectric sensors, piezoelectric sensors can not be used for static measurement, because after the external force of the charge, only in the loop with an infinite input impedance is saved. The actual situation is not the case, so this determines that the piezoelectric sensor can only measure dynamic stress.

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