| 摘要 |
A current transformer, includes, a Rogowski coil for detecting an alternating current of a main circuit, and outputting a measure of the alternating current as an analog-voltage signal, includes, a printed circuit board, a sensor unit and an optic transmission path. The printed circuit board with four conducting layers, having an opening at a center portion which a conductor penetrates, comprises metal foils, each extended in the shape of radiating from a center that is approximately the center of the opening, mounted on both sides of surface of the printed circuit board and on two inner conducting layers of the printed circuit board, a first winding formed by electrically connecting metal foils on a first outer side of surface of the printed circuit board and metal foils on a first inner conducting layer of the printed circuit board adjacent to the first outer side of the surfaces of the printed circuit board with first plated through holes penetrating the printed circuit board in a thickness direction, a second winding formed by electrically connecting metal foils on a second outer side of surface of the printed circuit board and metal foils on a second inner conducting layer of the printed circuit board adjacent to the second outer side of the surface of the printed circuit board with second plated through holes penetrating the printed circuit board in a thickness direction, the first winding and the second winding connected as mirror images of each other, and connected in series. The sensor unit comprises an analog-to-digital converter converting the analog-voltage signal into a digital electric signal, and an electric-to-optic converter converting the digital electric signal into a digital optical signal.
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