| 摘要 |
PURPOSE: To accurately detect d.c. component at a low cost by winding secon dary coil around magnetic core and short-circuiting the coil. CONSTITUTION: Secondary coil wire 36 is wound around a magnetic core 32 and is short-circuited. In this case, the value I of current to be detected 31 including a direct current component is I=A.sinΩt+IDC (A: amplitude, Ω: angular frequency, IDC: direct current component). If primary coil wire 35 for flowing of current to be detector is wound n1 turns around a magnetic core 32 and the turns of the coil wire 36 is n2 , the current I2 in the wire 36 is I2 =(n1 /n2 ) A.sinΩt. Only the magnetic flux Φ for the current difference IDC is generated in the magnetic core 32 and Φ=K.n1 .IDC (K: constant). This magnetic flux Φis detected by a hole element 33. Since the current IDC is 1% of the current I, the element 33 and an amplifier 34 can have a smaller copacitance than in the case of detecting the current I and thus the accuracy is improved. |
