Investigation On Test Method Of Emc Performance For Miniaturized PLC System

With continuous development of scientific technology, the applicationsof Programmable Logic Controllers (PLC) have been becoming increaselywide. PLCs have already substituted the traditional pneumatic or electricalcontrol system, and taken an irreplaceable position in industrial automaticcontrol area, especially in the sequence control. On the other hand, it is notedthat European Union (EU) enacted mandatory EMC new directives in1996.The products can enter into the EU market only if they comply with all EMCrequirements and pass the corresponding tests. It currently becomes a problemwhich must be solved how to validate PLC in EMC testings and how toevaluate the performances of the PLC products from different factories in areasonable way.This thesis takes the actual testings as examples to illustrate how toconfigurate the PLC products under test, compile the suitable program, set upthe hardware and software environments that are applicable for EMC tests,including digital, analog and other types of modules. The experimentsdescribed in the thesis such as ESD, EFT, surge and so on are all used theEMC equipments which complied with international standard. It based on thestandard requirements, product characteristics with a large number of studiescarried out. All aspects of EMC performance of the PLC products are beentested. It obtains the valuable test data and results, and the most reasonableand effective testing methods are rendered to accomplish the validation formany kinds of small-size PLC systems through the analysis of test results. Itmakes guarantee for the successful EMC validation of PLC system in project.In this paper, EMC studies are conducted respectively for each test, the contents of each chapter is divided into the following three areas:1. Testing purposes, principles, meaning, the real-life phenomena itsimulated, testing equipments used, etc.;2. The relevant EMC standards, the layout of the specific testenvironment, the pre-tested content to ensure the accuracy and reliability oftest results, such as calibration of uniform field area, normalized siteattenuation, etc.;3. Perform the test on the construction of PLC systems, obtain the testdata and analysis the results, determine the EMC performance of the products,and conclude the reliable test method to check the EMC capability of PLCproducts.