Electromagnetic flowmeter is composed of sensor and transducer.It is based on Faraday's law of electromagnetic induction, used to measure the volume flow of conductive liquid, is a speed meter.

There are many kinds of instruments used for measurement in industrial production sites, such as electromagnetic flow meter for flow measurement, intelligent ultrasonic flow meter, liquid level transmitter for liquid level and pressure measurement, pressure transmitter and other instruments, there is a common feature is the need for external power supply.Because receive the interference of electromagnetism wave, can bring about an effect to the measuring accuracy of instrument instrument, restrain electromagnetism interference to also become very important, how can ability restrain electromagnetism interference to instrument?Follow me to have a look below!

There are three main methods of electromagnetic interference suppression: shielding, filtering and grounding.

1、Shielding

Shielding is a measure used to reduce the outward or inward penetration of electromagnetic fields and is commonly used to isolate and attenuate radiation interference.According to its principle, shielding can be divided into electrostatic shielding, electromagnetic shielding and magnetic shielding.

The function of electrostatic shielding is to eliminate electromagnetic interference caused by distributed capacitance coupling between two circuits. The shielding body is made of low-resistance metal material, and the shielding body must be grounded.

The function of electromagnetic shielding is to prevent interference of high frequency electromagnetic field. The shielding body is made of metal material with low resistance, and the shielding metal can absorb and reflect electromagnetic field to achieve the purpose of shielding.

The function of magnetic shielding is to prevent the interference of low-frequency magnetic field. The shielding body adopts magnetic materials with high permeability and saturation to absorb or lose electromagnetic field to achieve the purpose of shielding.

The influence of electromagnetic interference is closely related to the distance. The closer it is to the interference source, the greater the interference field intensity and the greater the influence.In electronic instruments and meters, the layout of electronic components is often limited by the volume, often use low resistance metal materials or magnetic materials made of closed body, the protection distance between the elements or parts is not enough to isolate, in order to reduce or prevent static or electromagnetic interference.

2、Filtering

Filtering can suppress electromagnetic conduction interference.Sensitive electronic equipment conducts electromagnetic interference signals through power lines, telephone lines, control lines, signal lines, etc.Low pass filter is often used to filter the conduction interference, which can be effectively suppressed.However, in electromagnetic compatibility design, the characteristics of the filter must be taken into account: frequency characteristics, impedance characteristics, rated voltage and voltage loss, rated current, leakage current, insulation resistance, temperature, reliability, size and so on.

3、Grounding

In the equipment or device, grounding is to make the interference electricity generated by the equipment or device itself flow through the grounding wire and into the earth. It is usually used to suppress the conduction interference.The ideal grounding body is a zero potential, zero impedance physical entity, as a reference point for all signal levels in the relevant circuit, any unnecessary current through it will not produce a voltage drop.This ideal grounding entity is actually approximate.