| With the rapid development of science and technology and social economy,the intelligentization,informatization and intelligent electrical devices have been widely used in the field of industrial processing control products.Nowadays,the anti-electromagnetic interference problem has become an important problem which needs to be tackled in the application of industrial control products,and has become a core technology that is being studied in the whole world.It can effectively monitor the industrial objects only if these industrial control products work stably and credibly in a complex electromagnetic environment.This project is of high and practical values to the industry developing.By analyzing the characteristics of electromagnetic interference source for our industrial control products in a complex electromagnetic environment,we discussed the corresponding measures of the anti-electromagnetic interference and propose a hierarchical protected structure system in the system design of industrial control products.In such anti-electromagnetic interference system,the CPU and surrounding electronic devices are the core parts of the system,which affects whether the device could operate normally or not.Hence,we must manage to prevent from influencing our facilities.According to the electromagnetic compatibility type test to the products and founding out that all interference sources enter into the industrial system through their external port.Hence,when constructing the anti-electromagnetic protected system,we should take a series of pre-measures including absorption,diminution,filtering,isolation and so on to reduce these interferential signals,ensure that all useful signals are processed before access and prevent some interference from breaking through the protective system and damaging main units.The type test simulates the practical case of the industrial actual working environment and the results show the level of the tested-products'anti-interference.Through testing the product which was designed on the basis of the proposed electromagnetic interference protection structure and getting the immunity level,to prove the proposed hierarchical protection structure is effective and feasible or not.According to the proposed hierarchical anti-electromagnetic interference structure and implementation plan,a comprehensive design of the anti-electromagnetic interference is carried out when setting up the substation's isolating switch controller hardware platform,including the input and output channels,communication interface,power port and so on.Among them the processing control channels contains the disconnector's running state,the controller's own push-button and current status,the alternating current motor's electrical signal,the isolating switch's rotation angle and the operating mechanism motor's output control informations;And communication ports contains network interface,RS232 interface,RS485 interface and the I2C interface.For the invasion pathways of interference,we also adopt some special anti-electromagnetic measures in the PCB wiring design,controller's two template connection-ways,etc.After completing the product designs,we carry out some electromagnetic compatibility type tests in the State's Relay Protection Testing Center,and the designed product can pass the electromagnetic compatibility of bad environment on the 4th level detection.The test results prove that the designed product has good resistance ability to electromagnetic interference,and also further verify the efficiency of the proposed hierarchical anti-electromagnetic interference structure. |
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