All kinds of operating electrical equipment are related to each other and interact with each other in three ways: electromagnetic conduction, electromagnetic induction and electromagnetic radiation. Under certain conditions, it will cause interference, influence and harm to the running equipment and personnel.
The electromagnetic compatibility EMC discipline that emerged in the 1980s aims to study and solve this problem, mainly to study and solve the interference generation, propagation, reception, suppression mechanism and its corresponding measurement and measurement techniques, and based on this, The most rational principle of technical economy, clearly defined the level of interference generated, the level of interference resistance and the suppression measures, so that equipment in the same electromagnetic environment is compatible, and does not introduce into any entity in the environment. Electromagnetic disturbance.
The institutes for testing and testing electromagnetic compatibility (including electromagnetic interference and electromagnetic resistance) include the Suzhou Electric Apparatus Research Institute, the Aerospace Environmental Reliability Test Center, and the Environmental Reliability and Electromagnetic Compatibility Test Center.
Internal interference refers to mutual interference between various components inside an electronic device, including the following:
(1) The interference caused by leakage of the working power supply through the distributed capacitance and insulation resistance of the line; (related to the operating frequency)
(2) The signal is coupled to each other through the impedance of the ground wire, the power source and the transmission wire, or the interference caused by the mutual inductance between the wires;
(3) Some components inside the equipment or system generate heat, which may affect the interference caused by the stability of the components themselves or other components;
(4) The magnetic field and electric field generated by high-power and high-voltage components affect the interference caused by other components through coupling.
External interference refers to interference from a line, device or system by factors other than electronic equipment or systems, including the following:
(1) External high voltage and power supply interfere with electronic circuits, equipment or systems through insulation leakage;
(2) External high-power equipment generates a strong magnetic field in space, and interferes with electronic circuits, equipment or systems through mutual inductance coupling;
(3) interference caused by space electromagnetic waves to electronic circuits or systems;
(4) The temperature of the working environment is unstable, causing interference caused by changes in internal circuit components of the electronic circuit, equipment or system;
(5) Equipment powered by industrial power grids and interference generated by power grid voltages through power transformers.
Rapid development of electromagnetic compatibility technology
Electromagnetic waves exist everywhere in the nearly 1,000-kilometer space from the surface of the Earth to the activities of satellites. Electricity and magnetism affect people's lives and production all the time. The wide application of electromagnetic energy makes the development of industrial technology change with each passing day. While electromagnetic energy creates enormous wealth for human beings, it also brings certain harms. It is called electromagnetic pollution. Studying electromagnetic pollution is an important branch of environmental protection. In the past, the interference that the radio communication device was subjected to was called electromagnetic interference, which indicated that the device was invaded by external interference. In fact, it also caused damage to other external devices, that is, it became a source of interference. Therefore, it is necessary to study the interference and interference of the device at the same time, and attention should be paid to the compatibility between the tissues and devices inside the device. With the development of science and technology, the increasingly widely adopted microelectronic technology and the gradual realization of electrification have formed a complex electromagnetic environment. Continuous research and resolution of the relationship between equipment and systems in the electromagnetic environment has promoted the rapid development of electromagnetic compatibility technology.
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