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The main source of interference of the pressure transmitter and how to solve the interference problem

Nov 30, 2018

The main source of interference of the pressure transmitter and how to solve the interference problem


The pressure transmitter consists of a piezoresistive sensor and a signal conversion module. When the core component of the sensor is a single crystal silicon wafer, its resistivity changes. Four resistors are formed on the silicon wafer by semiconductor planar process, and connected into a Wheatstone bridge. Under constant current flow, a voltage signal proportional to the pressure signal can be output, and the signal conversion module processes the voltage signal of the sensor. , converted to 4-20mA standard signal. The pressure transmitter can be used to measure the pressure (liquid, gas and vapor) pressure, liquid level and other parameters, and convert the measured signal into a 4-20mA standard electrical signal output, which can be used as an indicator, recording and regulator. input signal. WP-800 pressure transmitter has the advantages of small size, light weight, high precision and low price. It can be equipped with on-site indication meter, zero point migration, range extension and other functions. It can be intrinsically safe and explosion-proof, with industrial pressure change. All functions of the transmitter.


pressure transmitter

The pressure transmitter adopts imported ceramic sensors with international advanced technology, and is equipped with high-precision electronic components. It is assembled into a stainless steel anti-corrosion structure with strict requirements. It is suitable for pressure measurement of general liquids and gases. It can be used to measure pressure in the fields of steel and chemical industry. It can be used with pressure regulator to realize automatic pressure control. The pressure transmitter has reliable operation, stable performance, convenient installation and use, small size, light weight and high performance-price ratio. It is widely used in various industrial self-control environments, involving water conservancy and hydropower, railway transportation, intelligent building, production automation, petrochemical, oil well, electric power, ship, machine tool, pipeline and many other industries. It is suitable for measuring the liquid level and density of liquid, gas or steam. And pressure, then the pressure signal is converted into a 4-20mADC signal output.


The main source of interference for pressure transmitters:


(1) Static induction


Electrostatic induction is due to the parasitic capacitance between two branches or components, so that the charge on one branch is transmitted to the other via parasitic capacitance, so it is also called capacitive coupling.


(2) Electromagnetic induction


When there is a mutual inductance between two circuits, the change of current in one circuit is coupled to the other through a magnetic field. This phenomenon is called electromagnetic induction. For example, magnetic flux leakage of transformers and coils, parallel wires for energization, and the like.


(3) Leakage current sensing


Due to poor insulation of component brackets, terminals, printed circuit boards, internal dielectrics or casings of the electronic circuit, especially in the application environment of the sensor, the insulation resistance of the insulator is reduced, resulting in an increase in leakage current, which may cause interference. Especially when leakage current flows into the input stage of the measuring circuit, its effect is particularly severe.


(4) Radio frequency interference


It is mainly the start of large power equipment, interference of operation stop and high harmonic interference. Such as the interference of the thyristor rectifier system.


(5) Other interference


In addition to being susceptible to the above disturbances, the on-site safety production monitoring system is also susceptible to mechanical interference, thermal interference and chemical interference due to poor operating environment.

The main source of interference of the pressure transmitter and how to solve the interference problem


How to solve the interference problem of pressure transmitter?


1. The package of the pressure transmitter.


The package of the transmitter, especially often overlooked, is its frame, however this will gradually reveal its shortcomings in later use. In the purchase of the transmitter must take into account the future working environment of the transmitter, how the humidity, how to install the transmitter, there will be strong impact or vibration.


2. What kind of connection is used between the pressure transmitter and other electronic devices.


Is it necessary to use a short-distance connection? If a long-distance connection is used, is it necessary to use a connector?


3. Select what output signal to use.


What output signals are required for the pressure transmitter: mV, V, mA, and frequency output digital output, depending on various factors, including the distance between the transmitter and the system controller or display, whether there is “noise” or other electronics Interference signal. Whether the amplifier, the position of the amplifier, etc. are required. For many OEM devices with short distances between the transmitter and the controller, the most economical and effective solution for mA output transmitters is to use a transmitter with built-in amplification if the output signal needs to be amplified. For long-distance transmission or strong electrical interference signals, it is best to use mA output or frequency output.


4. What excitation voltage is selected.


The type of output signal determines how the excitation voltage is selected. Many amplifiers have built-in voltage regulators, so their supply voltage range is large. Some transmitters are quantitatively configured and require a stable operating voltage. Therefore, a working voltage that can be obtained determines whether or not to use a sensor with a regulator. When selecting a transmitter, it is necessary to consider the operating voltage and system cost.


5. Is it necessary to have an interchangeable transmitter?


Determine if the required transmitter can accommodate multiple operating systems. Generally speaking, this is very important. Especially for OEM products. Once the product is delivered to the customer, the cost of the customer's calibration is considerable. If the product is interchangeable, even changing the transmitter used will not affect the overall system.


6. The pressure transmitter needs to maintain stability after working overtime.


Most transmitters will “drift” after a timeout, so it is important to understand the stability of the transmitter before purchasing. This pre-work can reduce the hassle of future use.


     Huaheng Instrument has its own R&D patents and relies on professional R&D and production technology to supply you with reliable and cost-effective professional pressure transmitters.