Patent ID: 6822547
Filing Date: 2004-11-23
Classification: G01R,H01F

Abstract:
A current transformer, comprising:a Rogowski coil which detects an alternating current of a main circuit of power distribution equipment or substation main circuits equipment, and outputs a measure of the alternating current as an analog-voltage signal, the Rogowski coil comprising, a printed circuit board of multilayer type comprising four conducting layers of interconnections, having an opening at a center portion which a conductor penetrates, a plurality of 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; and the first winding and the second winding connected as mirror images of each other, and connected in series, a sensor unit, comprising, an analog-to-digital converter which converts the analog-voltage signal into a digital electric signal, and an electric-to-optic converter which converts the digital electric signal into a digital optical signal; and an optic transmission path which transmits the digital optical signal to upstream system.