EMI test applications and related test standards

- May 31, 2017-

EMI test applications and related test standards

Electromagnetic interference EMI (Electromagnetic Interference), there are two kinds of conduction interference and radiation interference. Conducted interference refers to the fact that the signal on an electrical network is coupled (interfered) to another electrical network through a conductive medium. Radiation interference refers to the interference source through the space to its signal coupling (interference) to another electrical network. In high-speed PCB and system design, high-frequency signal lines, integrated circuit pins, all kinds of connectors and so may become a radiation source with antenna characteristics, can emit electromagnetic waves and affect other systems or other subsystems within the system normal work.


As we all know, EMC's test target is electrical and electronic equipment, and lighting equipment as one of the important one, naturally have the corresponding constraints. Such as the United States FCC certification, the EU's CE certification and so on LED lighting equipment related to the test project. When talking about electromagnetic interference, in general there are two kinds of interference sources; one is the conduction interference, mainly electronic equipment generated by the interference signal through the conductive medium or the public power line to interfere with each other, LED lamps FCC certification conducted interference scan Test frequency from 0.15MHz to 30MHz end, CE certification in the conducted interference scan test frequency from 9KHz to 30MHz end. Another kind of interference is radiation interference, mainly refers to the interference generated by the electronic equipment signal through the spatial coupling of the interference signal to another electrical network or electronic equipment, LED lamps FCC certified space radiation interference scanning test frequency from 30MHz to 1GHz At the end, the space radiation interference scan test frequency in CE certification starts from 30KHz to 300MHz.


In the lighting industry, in the test 9KHz-30MHz band EMI in two ways, one is to use Antenna (antenna) and EMI receiver, according to the standard is CISPR15, EN55015, GB17743. For low-frequency magnetic field equipment that may be produced by lighting fixtures, it is necessary to measure the low-frequency magnetic field radiation harassment using the tricyclic antenna specified in CISPR16-1-4. Mainly by the tricyclic antenna and EMI receiver for testing, testing room to be carried out in the shielding room. Note: The tricyclic antenna converts the X-direction, Y-direction and Z-direction low-frequency magnetic field components into RF signals and transmits them to the EMI receiver through three channels of the coaxial switch. The other is the LISN test method. By the EMI receiver + artificial power network + LISN and test software. The LISN enables RF signal isolation, sampling, impedance matching, and provides an electrical channel for the EUT. The EMI receiver measures the RF signal. The LISN achieves RF signal isolation, sampling, impedance matching, and provides an electrical channel for the EUT. The EMI receiver measures the RF signal. , And ultimately by the EMI test software for analysis, processing and limit. Test to be carried out in the shielding room.


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