EMC including EMI (interference) and EMS (susceptibility), that is, electromagnetic interference and electromagnetic interference.
EMI, electromagnetic interference, describes the electronic and electrical products in the normal working state of the outside world interference; EMI also includes conducted interference CE (conduction emission) and radiation interference RE (radiation emission) and harmonic harmonic.
EMS, electromagnetic immunity. Describes whether an electronic or electrical product will be affected by the interference of its surroundings or other electronic or electrical products in the same electrical environment and affect its own normal operation.
EMS also includes ESD (electrostatic discharge immunity), CS (conducted immunity), RS (radiated immunity), EFT (electrical fast transient pulse group immunity), Surge (surge immunity), and Voltage DIP and Interrupt (voltage drop immunity).
Expanded Information: EMC certification of three important laws: Law I, EMC cost-effective relationship law: EMC problems, the earlier the consideration, the earlier the solution, the smaller the cost, the better the results. In the new product development stage on the EMC design, than wait until the product EMC test failed to improve, the cost can be greatly saved, the efficiency can be greatly improved; on the contrary, the efficiency will be greatly reduced, the cost will be greatly increased. Law II, high-frequency current loop area S the larger, the more serious EMI radiation. High-frequency signal current flows through the inductor minimum path. When the frequency is higher, the general alignment reactance is greater than the resistance, the connection to the high-frequency signal is inductive, series inductance caused by radiation. Law No. 3, the higher the loop current frequency f, caused by the more serious EMI radiation, electromagnetic radiation field strength with the current frequency f square proportional to the increase. Reducing radiation harassment or improve RF radiation anti-interference ability of the most important way two, is to find ways to reduce the source of harassment of high-frequency current frequency f, that is, to reduce the frequency of harassment of electromagnetic waves. Baidu Encyclopedia-emc