The new edition of the CMC Sample Kit from Vacuumschmelze is available again. The kit contains a selection of nanocrystalline common mode chokes from the new range, in designs that conform to UL standards (using suitable plastics compliant with the UL-1446 standard for insulation materials). The kit includes an assortment of two winding common-mode chokes for singlephase applications in flat and upright designs as well as a number of threeand four winding chokes for three-phase applications.

The chokes are designed for operating currents ranging from 4 to 48A and for operating voltages from 300 to 1000V. The kit is now available from VAC distributors. VITROPERM is a nanocrystalline alloy offering a wide permeability range from 5,000 to over 150,000, combined with high saturation flux density of 1.2T.

The material properties typically allow the dimensions of chokes to be reduced by a factor of three in comparison to conventional ferrite chokes. Despite their high inductance, VAC chokes typically have a low number of turns and large copper cross-section, thereby reducing copper losses and improving system efficiency.

Nanocrystalline common mode chokes deliver extremely broadband attenuation, determined in the low-frequency range by the high level of material permeability and at higher frequencies by the low winding capacitance. In many cases, this broadband attenuation characteristic allows the development of EMI filters with a lower component count by reducing the number of filter stages.