EMI, electromagnetic interference, describes the interference of electronic and electrical products to the outside world under normal working conditions; EMI includes conducted interference ce, radiated interference re and harmonics.
EMS, electromagnetic anti-interference, describes whether an electronic or electrical product will be interfered by its surrounding environment or other electronic or electrical products in the same electrical environment, which will affect its normal work.
EMS also includes electrostatic anti-interference ESD, conduction anti-interference CS, radiation anti-interference RS, electrical fast transient immunity EFT, surge immunity surge, voltage sag immunity voltage sag and interruption.
Extended data:
Three principles of EMC certification:
Law one. EMC's Law of Efficiency-Cost Ratio: The sooner you consider and solve EMC problems, the smaller the cost, the better the effect.
EMC design in the new product development stage can greatly save costs and improve efficiency compared with waiting until the EMC test of the product fails. On the contrary, the efficiency will be greatly reduced and the cost will be greatly increased.
Rule 2: The larger the loop area S of high-frequency current is, the more serious the EMI radiation is.
The minimum path for high frequency signal current to flow through inductor. When the frequency is high, the reactance of the wiring is generally greater than the resistance, and the inductance used for high-frequency signals is connected, and the series inductance causes radiation.
Rule 3: The higher the loop current frequency f is, the more serious the EMI radiation is, and the electromagnetic radiation field strength increases in direct proportion to the square of the current frequency f. ..
One of the most important ways to reduce radiation disturbance or improve the anti-jamming ability of RF radiation is to find ways to reduce the high-frequency current frequency f of the disturbance source, that is, to reduce the frequency of the disturbance electromagnetic wave.
Baidu encyclopedia -emc