| 摘要 |
PURPOSE:To extend noise preventive characteristics to lower and higher frequency range sides by disposing an auxiliary core for forming a closed magnetic path having higher effective permeability in a low frequency range that of a main core and shorter magnetic path length in an AC line filter, and concentrically winding a part each of a pair of windings so as to simultaneously surround main and auxiliary cores thereby. CONSTITUTION:A pair of windings 4, 4' are provided at opposite positions on a core 8 for forming a closed magnetic path of an AC line filter, and an auxiliary core 9 having higher permeability in a low frequency range and shorter magnetic path length is disposed adjacent to the core 8 of the filter. The parts 11, 11' of the windings 4, 4' are so concentrically wound as to simultaneously surround the cores 8 and 9. A large inductance is provided by the magnetic fluxes phi1N-phi3N and phi'1N-phi'3N of the parts 10, 11, 12 against common mode noise currents Nc of the same phase applied to terminals 1, 1', and a small inductance is provided by the magnetic fluxes phi1S-phi3S, phi'1S-phi'3S of the parts 10, 11, 12 against the AC current S of normal mode, thereby extending a noise preventive characteristic to low and high frequency range sides.
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