Abstract: A low-loss Mn—Zn ferrite comprising Fe, Mn and Zn as main components, Co, Ca and Si as first sub-components, and at least one Va-group metal as a second sub-component: Fe and Zn being 53-56% by mol (calculated as Fe2O3) and 1-9% by mol (calculated as ZnO), respectively, and Mn being the balance, based on the total amount (100% by mol) of the main components; Co and Ca being 500-5000 ppm (calculated as Co3O4) and 3000 ppm or less (calculated as CaCO3), respectively, by mass based on the total amount of the main components, a mass ratio of Ca (calculated as CaCO3) to Si (calculated as SiO2) being 2 or more; Ta being 250 ppm or more (calculated as Ta2O5) among the Va-group metals; the ferrite having an average crystal grain size of less than 3.2 ?m and volume resistivity ? of 1 ?·m or more, and a power loss Pcv of 350 kW/m3 or less in a range of 0° C.-120° C. at a frequency of 2 MHz and a magnetic flux density of 25 mT.

Abstract: A low-loss Mn—Zn ferrite comprising Fe, Mn and Zn as main components, Co, Ca and Si as first sub-components, and at least one Va-group metal as a second sub-component: Fe and Zn being 53-56% by mol (calculated as Fe2O3) and 1-9% by mol (calculated as ZnO), respectively, and Mn being the balance, based on the total amount (100% by mol) of the main components; Co and Ca being 500-5000 ppm (calculated as Co3O4) and 3000 ppm or less (calculated as CaCO3), respectively, by mass based on the total amount of the main components, a mass ratio of Ca (calculated as CaCO3) to Si (calculated as SiO2) being 2 or more; Ta being 250 ppm or more (calculated as Ta2O5) among the Va-group metals; the ferrite having an average crystal grain size of less than 3.2 ?m and volume resistivity ? of 1 ?·m or more, and a power loss Pcv of 350 kW/m3 or less in a range of 0° C.-120° C. at a frequency of 2 MHz and a magnetic flux density of 25 mT.

Abstract: A high voltage transformer comprising a core with a closed magnetic flux path formed by at lease two core parts, at least two bobbins mounted on the side legs of the core, a primary coil and a secondary coil. The bobbin has a hollow through hole to receive the side leg, a low voltage side flange and a high voltage side flange at end portions. The primary coil is inserted in the low voltage side flange, and the secondary coil is regularly and orderly wound on the bobbin between the low voltage side flange and the high voltage side flange. The winding direction of the secondary coil of one of the bobbins is opposite to that of the secondary coil of the other bobbin. The regularly and orderly wound coil and the opposite winding directions decrease the potential difference between the adjacent turns in the second coil and minimize the potential difference between the opposing turns of the secondary coils which are placed parallel to each other.