CURRENT SENSOR AND MEASURING DEVICE

PROBLEM TO BE SOLVED: To output a signal via a transmission path in a state where attenuation is reduced, while high frequency noise is eliminated.SOLUTION: A current sensor includes: a coil 5 wound around a magnetic core 2 inserted with an electric path 21 to be measured in an inner part and connected to a ground G side at one end 5a and outputting from the other end a current I2 of the current value according to the current value of a current I1 to be measured and flowing in the electric path 21 to be measured; a constant impedance filter 7 in which an input terminal 7a is connected to the other end 5b of the coil 5 and the frequency region of a current I2 inputted from an input terminal 7a is limited to a desired frequency region and is outputted from an output terminal 7b; a transmission path 8 in which one end 8a is directly connected to the output terminal 7b of the filter 7; and a terminal resistor 9 connected between the other end 8b of the transmission path 8 and the ground G and converting the current I2 flowing via the transmission path 8 into a detecting voltage V2. The filter 7 has impedance viewing the terminal resistor 9 side from the input terminal 7a regulated to the same value as a characteristic impedance of the transmission path 8.SELECTED DRAWING: Figure 1 【課題】高周波ノイズを除去しつつ、減衰の少ない状態で伝送路を介して信号を出力する。【解決手段】内部に測定電路２１が挿通される磁気コア２に巻回されて一端５ａがグランドＧ側に接続されると共に測定電路２１に流れる被測定電流Ｉ１の電流値に応じた電流値の電流Ｉ２を他端から出力するコイル５と、入力端子７ａがコイル５の他端５ｂに接続されると共に入力端子７ａから入力される電流Ｉ２の周波数領域を所望の周波数領域に制限して出力端子７ｂから出力する定インピーダンスフィルタ７と、一端８ａがフィルタ７の出力端子７ｂに直接接続された伝送路８と、伝送路８の他端８ｂとグランドＧとの間に接続されて伝送路８を介して流れる電流Ｉ２を検出電圧Ｖ２に変換する終端抵抗９とを備え、フィルタ７は、入力端子７ａから終端抵抗９側を見たインピーダンスが伝送路８の特性インピーダンスと同じ値に規定されている。【選択図】図１