The full name of EMC test is Electro Magnetic Compatibility, which refers to the comprehensive evaluation of the degree of interference (EMI) and anti-interference ability (EMS) of electronic products in electromagnetic field, which is one of the important indicators of product quality. The measurement of electromagnetic compatibility is composed of test sites and test instruments. The purpose of EMC testing is to detect the impact of electromagnetic radiation generated by electrical products on the human body, the public power grid and other electrical products in normal operation. It is defined as "the ability of the equipment and system to work normally in its electromagnetic environment and not to constitute an unbearable electromagnetic harassment of anything in the environment" The definition contains two aspects of meaning, first, the equipment should be able to work normally in a certain electromagnetic environment, that is, the equipment should have a certain electromagnetic immunity (EMS); Secondly, the electromagnetic harassment generated by the device itself cannot have an excessive impact on other electronic products, that is, electromagnetic harassment (EMI).
EMC including EMI (Electromagnetic Interference) and EMS (Electromagnetic withstand) two parts, the so-called EMI electromagnetic interference, is the machine itself in the process of the implementation of due function is not conducive to other systems of electromagnetic noise; and EMS is the machine in the process of the implementation of due function is not subject to the influence of the surrounding electromagnetic environment.
1.EMI (Electro-Magnetic Interference) --- Electromagnetic Nuisance Test, the purpose of this test is: to detect the electromagnetic radiation generated by electrical products on the human body, the public power grid and other normal work of electrical products.
Conducted Emission-conducted nuisance test
Harmonic-Harmonic current test
Flicker-voltage variation and flicker test.
2. EMS (Electro-Magnetic Susceptibility) - Electromagnetic immunity test, the purpose of this test is to detect whether the electrical products can work stably in the electromagnetic environment without being affected.
ESD - Electrostatic Discharge Immunity Test
RS-Radio frequency electromagnetic field radiation immunity test
CS-conducted nuisance immunity test for RF field induction
DIP-voltage dips, short interruptions and voltage variations immunity test
SURGE-Surge (shock) immunity test
EFT-Electrical Fast Transient Pulse Flock immunity test
PFMF-Professional Frequency Magnetic Field (PFMF) immunity test.
Spurious definition: refers to the standard test signal modulation in addition to the carrier frequency and due to normal modulation and switching transients caused by the sidebands and neighbouring channels outside the discrete frequency radiation (both far-end radiation). Spurious radiation can be divided into conducted and radiated according to its source.
Conducted spurious: the level power of any discrete signal measured at the connector of the antenna 50 ohm load.
(EMC) is a very important quality indicators, it is not only related to the product itself, the reliability of the work and the use of safety, but also may affect the normal operation of other equipment and systems, related to the protection of the electromagnetic environment. EC government regulations, from 1 January 1996, all electrical and electronic products must be certified by the EMC, affixed with the CE mark before they can be sold in the EC market.
In the actual EMC test application, in addition to the identification test through the standard qualification laboratory, there are two other feasible methods are also recognised by the industry: TCF (Technical Construction File) and Self Ceritification (self-certification). Immunity testing is a very practical test item. A good way to achieve EMC is to treat all digital and analogue circuits as responding to high frequency signals, and to use high frequency design methods for electric charge shielding, PCB routing and common mode filtering. It is also important to use the entire ground plane and power plane, and this should be done for analogue circuits as well, which helps to limit the high-frequency common-mode loops. Most transient disturbances are high-frequency and generate strong radiated energy.