EMI测试项目及相关法规介绍.ppt

1 悬垂电缆末端与水平接地平板距离不足40cm,又不能缩短至适宜长度,超长部分折叠成30cm~40cm的线束; 2 电源线超长部分应在中心折叠成线束或缩短至适宜的长度; 3 EUT单独与一LISN 相连,其他周边设备通过多插座电源板接至另一LISN,LISN与EUT的水平距离应为80cm ; 4 带电周边设备之间相互距离为10cm,显示器可以直接放于控制器上面; 5 EUT及外设的后缘须与测试桌后缘切齐; 6 木桌后缘与垂直参考平面水平距离为40cm; LISN1 LISN2 传导测试示意图 The grass is greener on the other side of the hill E7405A ESCS 30 Conduction Emission Test Setup Control computer LISN2 LISN1 HHHHHHHHHHHHHHH Printer Ground Reference Plane Vertical Ground Reference Plane Line Impedance Stabilization Network Transient Limiter Two is company， but three is none EMI测试最小的PC架构: 1 个人电脑 2 键盘 3 视讯显示单元 4 对两种不同形式之I/O界面,(如串行 并行口)各接一个外接周边 5 EUT专属之有特殊目的之周边,如鼠标榜 摇感等 Our Conduction Test Area Conduction Set up LISN Harmonics Test谐波测量 测试目的 测量设备在工作时向电网注入的电源高次谐波的强度。看其是否符合法规要求。 Why are current harmonics a problem? 1.Reduction of the effective power factor of a load *increase of VA therefore higher cost for the electricity *higher cost based on higher rating of wires, connectors, filters, etc 2. Distortion of the a.c. supply voltage *products are affected e.g. filter capacitors, overheating or reduced efficiency of motors 3. EMC problems *increased harmonics current in the neutral and protective earth Harmonics Source The non linear load EUT generates a impulse current. Over the resistors R1 a voltage drop in line with the impulse current occur. The nonlinear impulse current is an emission of the EUT. Loads on V2 can be influenced. EUT V2 R2 R2 V1 R1 Vac Non-Liner Loads voltage Non-sinusoidal e.g.:switch-mode power supply in computer, printer, television etc current Non-sinusoidal e.g.:switch-mode power supply, With diode bridge etc IEC61000-3-2 Scope Product Family Standard Power range -230 Vrms single or three phase. For system voltages less than 220V (line to neutral), the limits have not yet been considered -Irms maximum 16A -50Hz/60Hz Measurements -measurement harmonics from 2nd to 40th Measurement Standard IEC61000-4-7