Nanocrystalline Common Mode Chokes for Line Filters

Common mode chokes are used as in line filters to reduce broadband mains-borne radio interference. Wurth Electronics has developed current-compensated common mode chokes with nanocrystalline cores for this purpose. The new WE-CMBNC product family is made with nanocrystalline cores and features broadband attenuation. Compared with conventional cores made of MnZn and NiZn core materials, nanocrystalline cores have 20 times more permeability. Mains borne interference can, thus, be reduced down into the low kHz frequency range, where conventional NiZn and MnZn cores have very little attenuate effect. Even in high frequency ranges, high levels of attenuation can be achieved due to the low winding capacitance. Compared with conventional cores, the Currie temperature is about three times higher, so push-pull interference cannot result in saturation.