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COSEL Power Supply, Noise Filter 2025 Product Catalog
1Noise BasicsOutput ripple noise from a switching power sourceis also a type of high-frequency noise.Ripple noise can be reduced with a DC filter designedfot it.SwitchingEMI FilterpowerLoadsupplyINOUTLCA50S-12LCA50S-12+SNA-06-223Normal temperature,Normal humiditBW:500MHzLCA50S-1212V 4.3A10mV/DIV 4μs/DIV10mV/DIV 4μs/DIVFigure 1.7.2 Example of Effectivemess ofRipple Noise Filterc. Surge noiseThis noise occurs when a natural discharge (such aslightning) affects a power line. As the generatedvoltage reaches as extremely high as a few kilovoltsor more, EMI filters cannot suppress surge noise. Asan antinoise measure, one could use a part such as avaristor to control surge voltage between power linesor between a power line and ground. EMI filters canwithstand approximately 2 kV between power linesand approximately 4 kV between a power line andground (these values are not guaranteed).If surges are a concern, surge countermeasuresshould be selected and installed to handle the EMIfilter’s capabilities.EMI FilterElectroniccontrolLINELOADapparatusb. Pulse noiseThis noise is generated when a relay or motor is driven.As peak voltage may reach as high as a few thousandvolts, generic filters may not be able to sufficientlyattenuate noise because its choke coil gets saturated.As an antinoise measure, one could select a filter thatuses an amorphous core for its superior pulse attenuationcharacteristic.Anti-surge PartsFigure 1.7.4 Proper Installation Location ofsurge CountermeasvresPulse noiseEMI FilterLINELOADElectroniccontrolapparatus[Pulse attenuation characteristic Pulse width: 11μs]200Output voltage [V]10000 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0Input voltage [kV]Figure 1.7.3 Example of Pulse AttenuationCharacteristic(NAP-16-472)EMI/EMCFilterTechnical Notes-4? 762 ?
