CURRENT TRANSFORMER STRUCTURE FOR CURRENT SENSOR

PROBLEM TO BE SOLVED: To effectively suppress the transfer of a common-mode voltage to a secondary circuit due to a capacitative coupling between a line to be measured and a current transformer. SOLUTION: A current transformer 11 has a coil winding 13 at a magnetic core in nearly ring shape, an insulation layer being provided on the outer surface, and a feed through port 16 where a line L to be measured that is connected in series with a primary side power supply line is inserted. Also, an electrostatic shield 21 where the winding direction of the coil winding 13 is discontinuous covers an opposite surface site of at least line L to be measured of the insulation layer and an adjacent site that continues the opposite surface site, while it is connected to the ground of an equipment body via a grounding wire 27.