Effects of Electromagnetic Interference on People and Electronic Devices

Recently, a notice issued by the China Consumers Association concerning the power supply plug of computers having radiation interference higher than the national standard was released, which is likely to affect other electronic devices in the power grid, and finally lead to a computer crash. The main cause of this interference is that the radiation interference from the power supply terminal of computers exceeds the limits set by the national standards, and this interference may interfere with the normal operation of other electronic devices, especially high-sensitivity electronic devices.

EMI-9KB_EMI Receiver System

With the development of science and technology and the increasingly digitized and high-speed electrical and electronic equipment used in all areas of society, electromagnetic interference brought by the application of electrical and electronic equipment has also brought electromagnetic pollution problems to society. And electromagnetic pollution and water pollution, air pollution are known as the three major sources of pollution in today’s society. With the increasingly prominent electromagnetic interference problem, the International Special Committee on Radio Interference (CISPR) has issued CISPR-16, CISPR-15, the European Standard Committee has issued EN55015 and EN55022 standards, etc. These measures and standards are designed to regulate the electromagnetic interference limitation of point electronic products and other specifications, so as to reduce the social problems caused by electromagnetic interference.

Electromagnetic interference(EMI) is divided into two types: conductive interference and radiation interference. Conductive interference refers to the coupling (interference) of a signal on one electrical network to another through a conductive medium. Radiation interference refers to interference source coupling (interference) its signal to another electrical network through space. In high-speed PCB and system design, high-frequency signal lines, pins of integrated circuits, various connectors, etc. may all become radiation interference sources with antenna characteristics, which can emit electromagnetic waves and affect the normal operation of other systems or other subsystems in the same system. As is known to all, the test target of EMC is electronic and electrical appliances, and lighting equipment as an important part, naturally also has corresponding constraints. Such as the FCC certification in the United States, the CE certification in the European Union and so on have put forward the relevant test items on the LED lighting equipment. When it comes to electromagnetic interference, there are generally two sources of interference; One is the conductive interference, mainly the interference signals generated by the electronic equipment through the conductive medium or common power line mutually interfere each other, LED lamps FCC certification of conductive interference scan test frequency from 0.15MHz began to 30MHz end, CE certification conductive interference scan test frequency from 9KHz began to 30MHz end.

The other is the radiation interference, which mainly refers to the interference signals generated by electronic equipment and coupled to another electrical network through space. The FCC certification space radiation interference scan test frequency of LED lamps is from 30MHz to 1GHz, and the space radiation interference scan test frequency of CE certification is from 30KHz to 300MHz. In the lighting industry, there are two methods of EMI, Frequency 9KHz-30MHz testing, one is using Antenna ( Antenna) and EMI receiver, its basis standard is CISPR15, EN55015, GB17743. For lighting equipment may produce the low frequency magnetic field device, need to adopt CISPR16-1-4 three-ring antenna to measure the low-frequency magnetic field radiation interference. It is mainly tested by three-ring antenna and EMI receiver, and the test should be carried out in the shielded room. Note: The three-ring antenna converts the low-frequency magnetic field components of the X, Y and Z directions into the RF signal, and transmits them through the coaxial switch to the three channels to the EMI receiver for measurement; Another is the use of LISN test method, the test need by EMI receiver + artificial power network + LISN and test software for. The EMI test system is used to measure the interference generated by the power port of the lamp and the lighting equipment in the normal working state, LISN realizes the isolation, sampling, impedance matching of the RF signal, and provides the electric channel for the EUT, the EMI receiver measures the RF signal, and finally the EMI test software analyses, processes and judges. The test should be done in the shielded room.

At the same time, for the 9KHz-300MHz wave band EMI testing, CDN method is used. In CISPR15, EN55015 and GB17743 standards also provide another type of lighting equipment electromagnetic field interference test method, that is CDN common mode terminal voltage method. Using CDN method, mainly include EMI receiver, CDN and attenuator. The test can be done in the shielded room. For the EMI test, the International Special Committee on Radio Interference (CISPR) promulgated the CISPR-16 wireless interference and anti-interference measurement instruments and specifications, and for the lighting industry, the International Special Committee on Radio Interference also proposed the CISPR-15 electronic lighting and related equipment wireless interference characteristics limit and measurement methods, and various countries also put forward various kinds of EMI lighting testing specifications according to the national situation, such as EN55015-2007 in the European Union, GB17743-1999 in China. For the EU countries, EN55015 standard (Reference CISPR-15) is applicable for Frequency more than 100Hz traditional lighting equipment, such as incandescent lamps, fluorescent lamps, self-rectifier and energy-saving lamps. These devices usually do not exceed 30MHz, with corresponding radiation interference limits. But for the new LED lighting industry, usually the frequency is over 30MHz, and the scan frequency from 30MHz to 300MHz is clearly put forward in the CE certification.

Two EMI test systems were developed and produced by LISUN according to relevant basic standards such as CISPR16. For traditional and new lighting industry standards, the scanning frequency of the two devices is different. The KH3962 EMI scanning frequency is 9KHz-300MHz, which is suitable for LED and traditional lighting device testing; the KH3961 EMI scanning frequency is 9KHz-30MHz, which is mainly suitable for traditional lighting device testing. In order to judge whether the tested object meets the standard, we refer to the three values of peak, quasi-peak and average to make the judgement. Considering the differences of different standards, the software can directly call the judgement standards such as GB17743, FCC, EN55015, GB4343, etc.

Lisun Instruments Limited was found by LISUN GROUP in 2003. LISUN quality system has been strictly certified by ISO9001:2015. As a CIE Membership, LISUN products are designed based on CIE, IEC and other international or national standards. All products passed CE certificate and authenticated by the third party lab.

Our main products are Goniophotometer, Integrating Sphere, Spectroradiometer, Surge Generator, ESD Simulator Guns, EMI Receiver, EMC Test Equipment, Electrical Safety Tester, Environmental Chamber, Temperature Chamber, Climate Chamber, Thermal Chamber, Salt Spray Test, Dust Test Chamber, Waterproof Test, RoHS Test (EDXRF), Glow Wire Test and Needle Flame Test.

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