PURPOSE: To enhance accuracy by avoiding the influence of an external magnetic field, by providing a core with a gap inlaid with and inserted into a conductor being a current detecting object and a magnetooptical effect element arranged in the gap of said core.
CONSTITUTION: A current transformer apparatus is constituted so that magnetic flux ϕm proportional to the density of a current flowing through a conductor passes a core 7 by said current and the magnetic field thereof is applied to the Faraday element 9 arranged in the gap 8 of said core 7. In this case, electromotive force is also induced in coils 10, 11 by the magnetic flux ϕm but, because both coils 10, 11 are same in winding numbers and subjected to inverse polarity connection, no current flows and, therefore, magnetic flux due to the coil 10 is not generated and no influence is exerted upon the Faraday element 9. As a result, the influence of an external magnetic field can be avoided and accuracy can be enhanced.
COPYRIGHT: (C)1984,JPO&Japio