The above list of EMI filters can be designed as frequent-manner filters by bringing in yet another reference conductor. As is properly-regarded, frequent-mode currents are induced by way of parasitic capacitance to an outdoor reference, like metal in the chassis or some exterior conductor (i. Here's a list of some https://stephenatcpg.full-design.com/an-unbiased-view-of-emc-vs-emi-filter-73848087