Pressure Sensor Unavoidable Error

- Oct 13, 2017-

A Pressure Transducer is a device or device that can feel the Pressure signal and can convert the Pressure signal to a usable output in accordance with certain rules.

Pressure sensors are usually composed of pressure-sensitive elements and signal processing units. According to different test pressure types, pressure sensors can be divided into table pressure sensors, differential pressure sensors and absolute pressure sensors.

Pressure sensor is the most common industrial practice, a sensor, its widely used in various industrial control environment, involved in water conservancy and hydropower, railway transportation, intelligent buildings, production control, aerospace, military industry, petrochemical, oil, electric power, ships, machine tools, pipe, and many other industries, the following is a brief introduction some commonly used sensor principle and its application. There are also medical pressure sensors

Overloaded pressure sensor is a kind of sensor, but we seldom hear this kind of pressure sensor, it is commonly used to transport applications, through the monitoring of the pneumatic, hydraulic, brake light load pressure, oil pressure, transmission device, as well as the truck/trailer air brake system, hydraulic pressure, flow and liquid level to sustain heavy equipment performance.

Overload pressure sensor is a pressure measuring device with shell, metal pressure interface and high level signal output. Many of the sensors come with round metal or plastic housing, with a tubular shape, a pressure port at one end and a cable or connector on the other. Such overload pressure sensors are often used in extreme temperatures and electromagnetic interference environments. Customers in the industrial and transportation sectors use pressure sensors in the control system to realize pressure measurement and monitoring of fluids such as coolant or lubricants. At the same time, it can detect pressure peak feedback in time and find problems such as system blocking, so as to find solutions immediately.

Overloaded pressure sensor has been developing, overloaded pressure sensors in order to be used in more complex control system, the design engineer must improve the sensor precision need to reduce costs at the same time to facilitate the practical application requirements, etc.

Connection method

Sensor wiring has always been one of the biggest customers purchasing process consulting, many customers do not know how sensor wires, in fact, the connection mode of various sensors basic are the same, there are generally two pressure sensors wire, three wire system, four wire system, some have five wire system.

Pressure transducer two wire system is simple, general customer all know how to wiring, a line connecting the power supply positive, another line is the instrument is connected to the negative power supply line, this is the simplest, pressure sensor three-wire system is based on two wire system added a line, this wire is directly connected to the power of the cathode, a two wire system a little trouble. The four-wire pressure sensor must be two power input terminals, and the other two are signal output terminals. The four-wire system is mostly of voltage output instead of 4~20mA output, 4~20mA called pressure transmitter, most of which are made of two-wire system. The signal output of the pressure sensor is not magnified, and the output of the full range is only a few tens of millivolts, while some pressure sensors have an amplifying circuit inside, and the full range output is 0~ 2V. As for how to receive the display instrument, the measuring range of the meter should be measured. If there is a gear that is suitable for the output signal, it can be directly measured, otherwise it will be added signal to adjust the circuit. The five-wire pressure sensor is not much different from the four-wire system, and there are fewer sensors on the market.

Unavoidable error

In selecting the pressure sensor, we should consider his comprehensive accuracy, and the precision of the pressure sensor is affected by what? In fact, there are many factors that cause the error of the sensor. The following are the four unavoidable errors. This is the initial error of the sensor.

First, the offset error: because the pressure sensor's vertical deviation is constant throughout the pressure range, the change of converter diffusion and laser adjustment correction will generate offset error.

The second is the sensitivity error: the error size is proportional to the pressure. If the sensitivity of the device is higher than the typical value, the sensitivity error will be the increasing function of pressure. If the sensitivity is lower than the typical value, the sensitivity error will be the decreasing function of pressure. The cause of this error is the change of diffusion process.

The third is the linear error: this is an initial error of pressure sensor affected factors, the causes of the error is physical nonlinear of silicon, but for sensor band amplifier, should also include the nonlinear amplifier. The linear error curve can be a concave curve or a convex curve weighing sensor.

Finally, the lag error: in most cases, the lag error of the pressure sensor is negligible, because the silicon chip has a high mechanical stiffness. In general, the lag error can be considered only in situations where the pressure varies greatly.

The four error of pressure sensor is inevitable, we can only choose high precision production equipment, using high and new technology to reduce these errors, also can be in when they leave a certain error calibration, doing their utmost to reduce the error to meet the needs of the customers.

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