Recently, there was an announcement issued by the China Consumers Association about the unqualified computer radiation harassment exceeding the standard, which may easily affect the equipment in the power grid and eventually cause the computer to crash . The main reason is that the computer power terminal radiation disturbance exceeds the limit value stipulated by the national standard, and this disturbance may interfere with the normal operation of other electronic equipment, especially high-sensitivity electronic equipment. With the development of science and technology, more and more digital, high-speed electrical and electronic equipment are widely used in various fields of society. While promoting social development, electromagnetic interference generated by the application of electrical and electronic equipment >It also brings electromagnetic pollution problems to the society. Electromagnetic pollution, water pollution, and air pollution are known as the three major pollution sources in today's society. With the increasingly prominent problem of electromagnetic interference, the International Special Committee on Radio Interference (CISPR) has issued CISPR-16, CISPR-15, and the European Standards Committee has issued standards such as EN55015 and EN55022. These measures and standards aim to standardize the electromagnetic interference limits and test specifications of point electronic products in order to reduce the social problems caused by electromagnetic interference.
Electromagnetic Interference EMI>(Electromagnetic Interference), yes There are two kinds of conducted interference and radiated interference. Conducted interference refers to the coupling (interference) of a signal on one electrical network to another electrical network through a conductive medium. Radiation interference refers to the interference source coupling (interference) its signal to another electrical network through space. In high-speed PCB and system design, high-frequency signal lines, integrated circuit pins, and various connectors may become radiation interference sources with antenna characteristics, which can emit electromagnetic waves and affect other systems or other subsystems in this system. normal work. As we all know, the EMC test target is electronic and electrical equipment, and lighting equipment, as an important part of it, naturally has corresponding constraints. For example, the FCC certification of the United States and the CE certification of the European Union have proposed relevant test items for LED lighting equipment. When talking about electromagnetic interference>, generally speaking, there are two sources of interference;The power lines interfere with each other. The frequency of conduction interference scan test for FCC certification of LED lamps starts from 0.15MHz to 30MHz, and the frequency of conduction interference scan test in CE certification starts from 9KHz to 30MHz. Another type of interference is radiation interference, which mainly refers to the interference signal generated by electronic equipment passing the interference signal to another electrical network or electronic equipment through space coupling. The FCC certification space radiation interference scanning test frequency of LED lamps starts from 30MHz to 1GHz At the end, the space radiation interference scanning test frequency in CE certification starts from 30KHz and ends at 300MHz. In the lighting industry, there are two methods for testing EMI in the 9KHz-30MHz band, one is to use Antenna (antenna) and EMI receiver, and the standards are CISPR15, EN55015, GB17743. For low-frequency magnetic field equipment that may be generated by lighting fixtures, it is necessary to use the three-loop antenna specified in CISPR16-1-4 to measure its low-frequency magnetic field radiation disturbance. It is mainly tested by the three-loop antenna and EMI receiver, and the test needs to be carried out in a shielded room. Note: The three-loop antenna converts the low-frequency magnetic field components in the X direction, Y direction and Z direction into RF signals, and transmits them to the EMI receiver for measurement through the three channels of the coaxial switch; the other is to use the LISN test method, which requires Conducted by EMI receiver + artificial power network + LISN and test software. The conducted disturbance test system is used to measure the disturbance generated by the power port of lamps and lamps and lighting equipment under normal working conditions. LISN realizes the isolation, sampling and impedance matching of RF signals, and provides electrical channels for EUT. EMI receivers measure RF signals , and finally analyzed, processed and judged by the EMI test software. The test shall be carried out in a shielded room.
At the same time, the CDN method is used in the EMI test of the 9KHz-300MHz band. In CISPR15, EN55015 and GB17743 standards, there is another test method for radiated electric field disturbance of lighting equipment, that is, the CDN common mode terminal voltage method. Adopt CDN method, mainly including EMI receiver, CDN and attenuator. The test can be carried out in a shielded room. For EMI testing, the International Special Committee on Radio Interference (CISPR) issued CISPR-16 Radio Interference and Anti-Interference Measuring Instrument Specifications, and for the lighting industry, the International Special Committee on Radio Interference also proposed CISPR-15 Electronic Lighting and Related Equipment Radio Interference Characteristic limitations and measurement methods, and various countries have also issued various EMI lighting testing specifications according to their own conditions, such as EN55015-2007 issued by the European Union, and GB17743-1999 issued by China. For EU countries, the EN55015 standard (citing CISPR-15) is suitable for traditional lighting equipment with a lamp frequency exceeding 100Hz, such as incandescent lamps, fluorescent lamps, self-rectifying energy-savinglights etc. Usually the frequency of such equipment does not exceed 30MHz, and the corresponding radiation interference limit table. But for the new LED lighting industry, the frequency usually exceeds 30MHz, and the scanning frequency is clearly stated in the CE certification from 30MHz to 300MHz.
Electromagnetic radiation interference limit
According to relevant basic standards such as CISPR16, Lisun has developed and produced two EMI tests system, and for traditional and new lighting industry standards, the scanning frequencies of the two devices are different. The KH3962 EMI scanning frequency is 9KHz~300MHz, which is suitable for the detection of LED and traditional lighting equipment; the KH3961 EMI scanning frequency is 9KHz~30MHz, which is mainly suitable for traditional Inspection of lighting equipment. To determine whether the measured object meets the standard, we quote the peak value, quasi-peak value and average value to judge. Considering the differences of different standards, the software can directly call GB17743, FCC, EN55015, GB4343 and other judgment standards.