Multifunctional Test System-LISN Used For Conducted Interference Test

With the application of the electric productions,conducted interference has become a kind of social effects of pollution.For which,all countries of the world had constituted relevant standards according to Electromagnetic Compatibility(EMC) of electric equipment.Any of the electric productions which don't accord EMC standard can't be allowed to appear in market.So how to improve the EMC of electric productions has become a key factor to make productions take up the market and reduce the cost.So it is very essential to make a kind of electromagnetic test apparatus used for preliminary EMI test.According to the effect mechanism of EMI,the ways it works are radiation and conduction.In the range of low frequency,Conducted interference is primary pass.To measure the Conducted interference of electric productions,we sometimes don't need to enter the shield room,but need to use the measure equipments:the equipment for receiving,line impedance stabilization network(LISN),stroboscope oscillograph and so on.As an important part in conducting measure system LISN is the object that is being studied in this paper.Firstly,the conducted interference is illustrated.Secondly,the origin,functions and types of LISN are analyzed.Based on analyzing and comparing all kinds of LISN,the filter is studied.Ferthermore,other hardware circuits are designed,for example,L/N line seletion circuit,attenuation circuit and the interface circuit between RS232 and computer.To control the function circuit,the control program is compiled with C language and the man-machine interface is designed with VB.