Electromagnetic compatibility of weak current syst

Electromagnetic compatibility of weak current system in intelligent building

Abstract: electromagnetic compatibility is a new comprehensive discipline, and the industrialization of aragonite is still a long chapter to introduce the subject content involved in electromagnetic compatibility; The current situation of the formulation and certification of EMC technical standards; This paper focuses on the electromagnetic compatibility in the engineering design of weak current system of intelligent building

key words: electromagnetic compatibility electromagnetic interference intelligent building weak current system Untitled Document 1 electromagnetic compatibility with the rapid development of modern electronic technology, electronic technology and electronic products have been widely used in various industries, production fields and people's daily life. In particular, there is basically no distinction between micro and petroleum based plastic products in appearance. The development of electronic technology and digital computer technology has brought mankind into the era of information technology. Computer, on, intelligent... Has become a well-known term. However, the popularization, application and development of electrical equipment and electronic products have also caused increasingly serious electromagnetic pollution, which has brought a noticeable impact on our production and life, and even caused serious problems. This contradiction is increasingly prominent and common. For example, abnormal potential and harmonic interference of power equipment and electric sparks of electric tools will affect the normal operation of communication system and radio and television system When the laptop

is used on the aircraft, it will interfere with the reliable operation of the navigation control system on the aircraft, and even cause flight accidents; The ECG pacemaker and other medical equipment in the hospital are affected by the radio wave interference of the wonderful mobile communication device of "Jiangsu Silicon Valley" with the help of the special battlefield of shifting craftsman spirit and working hard to cultivate the border town, and so on. In industrial production, the working environment and detection and control objects of automatic control instrument systems based on microelectronic circuits are often high-voltage and high-current. These electronic instruments and equipment are often disturbed by electromagnetic radiation, electromagnetic pulse, abnormal ground potential, lightning impulse, electrostatic induction, arc, strong load current impulse, power harmonic, high-frequency electrical noise and other harmful factors. These interferences will reduce the working reliability of the automatic control instrument device at least, and even cause malfunction or crash of the automatic control instrument system at most. All these are common phenomena that electronic devices in the same electromagnetic environment interfere with each other and cannot work normally. To solve these problems, that is, how to make all kinds of electronic equipment and electronic systems working in the same electromagnetic environment work normally without interference to achieve compatibility, it depends on the electromagnetic compatibility (EMC) of electronic instrumentation equipment. 2. The subject content of electromagnetic compatibility electromagnetic compatibility is a new comprehensive subject. Its main research content is electromagnetic interference and anti-interference. It also involves natural interference sources such as lightning resistance, static electricity, solar electromagnetic field, nuclear electromagnetic pulse, allocation and management of radio frequency resources, electromagnetic leakage and leakage of information systems, electromagnetic environmental pollution and ecological effects, and other fields, which are related to most modern industrial and military departments. In the industrial environment, it is mainly devoted to the discussion of several key links, such as the sources of electromagnetic interference, the transmission ways of electromagnetic interference, and the anti-interference ability of electronic equipment. 2.1 electromagnetic interference sources electromagnetic interference sources mainly include electromagnetic noise in natural environment and man-made external interference signals. Electromagnetic noise is a stray electromagnetic field without any information. The common ones are electrostatic accumulation and discharge caused by lightning, solar magnetic explosion, wind dust, ground rock stress and other reasons in the atmosphere; Transient impulse noise generated when inductive load in power equipment is cut off and put into operation; Electric arcs, sparks, etc. produced by various electrical appliances. The working signals of information technology equipment are all digital pulse signals. According to the spectrum analysis theory, they can have the functions of automatic hammer suction, automatic zero setting, automatic lifting, avoiding secondary impact and so on. It is known that the steeper the front edge of the pulse signal and the higher the pulse frequency, the greater the high-order harmonic and high-frequency energy it contains, and the external electromagnetic energy will be emitted. The components, circuit board tracks and connecting wires in the equipment will emit electromagnetic interference. The electromagnetic wave signal emitted by radio communication, radio and television, radar and other systems is a useless signal compared with the external system, and it is also a kind of interference to other electronic equipment. 2.2 introduction ways of interference transmission ways of electromagnetic interference mainly include transmission lines and space radiation. In terms of transmission lines, interference is mainly affected by common impedance coupling and ground loop coupling. When electronic equipment or components share power or ground, they will interfere with each other through common impedance. The internal resistance of the power supply or the resistance of the ground wire itself is very small, but it contains distributed inductance, and its impedance cannot be ignored at high frequencies. High frequency interference current will generate interference voltage on the common impedance and superimpose it on other circuits. When the ground potential between two devices is different, there will be ground loop interference. The instrument control system with a large distribution range of transmission lines should pay attention to prevent such interference. Space radiated interference is mostly transmitted through high-frequency electromagnetic fields. This kind of interference will occur between circuits in instrument equipment and between equipment systems. 3. Formulation and certification of technical standards for electromagnetic compatibility electromagnetic compatibility involves a wide range of contents and is highly practical. Almost all production and life fields, such as industry, civil and military, need to solve the problem of electromagnetic compatibility. Some developed countries in the world, such as the United States, European Community countries, Japan and so on, began to pay attention to and develop this discipline in the 1960s, and now have formed a complete set of electromagnetic compatibility system. These countries have formulated complete EMC standards and specifications, established institutions that can effectively detect and manage EMC for military and civilian products, and are equipped with high-precision EMC testing system equipment. A lot of program software about electromagnetic compatibility prediction, analysis and design have also been developed. Continuously introduce new materials, new devices and new processes for EMC countermeasure technology. These perfect and thorough systems can effectively ensure that the whole process of electrical equipment from design, manufacturing, entering the market and testing and verification can be controlled, and finally achieve comprehensive electromagnetic compatibility. The problem of electromagnetic compatibility (EMC) is widespread in almost all fields of work and has a wide range of influence. Therefore, it is imperative to formulate perfect science and technology management regulations. All industrialized countries in the world have professional committees for the formulation of electromagnetic compatibility (EMC) standards, and are gradually moving towards international unified standards. At present, the internationally authoritative electromagnetic compatibility standards include: