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COSEL Power Supply, Noise Filter 2025 Product Catalog
3How to Use EMI Filters1Ground WiringWhen wiring an EMI filter with a ground wire, use awire as thick and short as possible.A long ground wire will deteriorate attenuation of highfrequencies due to inductance in the wire.Long ground wire100908070Long ground wireShort ground wireLevel [dBμV]605040302010Short ground wireChassis ground00.1 1 10 100Frequency [MHz]Figure 3.1.1 Example of Ground wiringEffed on NoiseIf customers connect the metal chassis of their EMIfilter, they can obtain an effect similar to a shortground wire.Chassis groundFigure 3.1.2 Proper grounding2Input and Output WiringSeparate input wires from output wires.If one binds input and output wires of EMI filters, orlays them close to each other, the filters may lose theirproper attenuation effect because the high-frequencynoise component may bypass them.Twisting input (and / or output) wires in pairs canredvce noise.10090Input and output wires bundled(small distance between wires)BreakerLINEEMIFilterLOADMotordriver8070Input and output wires bundled(small distance between wires)BreakerLevel [dBμV]605040302010Input and output wires kept separateInput and output wireskept separateLINEEMIFilterLOAD00.1110100Frequency [MHz]Figure 3.2.1 Example of Effect ofwiring on NoiseMotordriverFigure 3.2.2 Input and output wiresEMI/EMCFilter? 769 ?Technical Notes-11
