With the development of electrical and electronic technology, the increasing popularity of household appliances and electronic products, radio and television, post and telecommunications and computer networks are increasingly developed, the electromagnetic environment is becoming increasingly complex and deterioration, so that the electrical and electronic products of the electromagnetic compatibility (EMC electromagnetic interference EMI and electromagnetic anti-EMS) issues have been the governments and manufacturers of the increasingly Attention. Electromagnetic compatibility of electronic and electrical products (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, the relationship between the protection of the electromagnetic environment. In order to standardize the electromagnetic compatibility of electronic products, all developed countries and some developing countries have formulated electromagnetic compatibility standards. EMC standards are the basic requirements to enable products to work properly in the actual electromagnetic environment. The reason why they are called basic requirements means that even if a product meets the EMC standards, interference problems may occur in actual use. Most national standards are based on those developed by the International Electrotechnical Commission (IEC).
EMC (Electro Magnetic Compatibility) is the full name of Electro Magnetic Compatibility, which is defined as "the ability of equipment and systems to function properly in their electromagnetic environment without causing intolerable electromagnetic disturbances to anything in the environment". The definition contains two meanings, first, the device should be able to work normally in a certain electromagnetic environment, that is, the device should have a certain degree of electromagnetic immunity (EMS); Second, the device itself produces electromagnetic harassment can not produce excessive impact on other electronic products, that is, electromagnetic harassment (EMI).