IRON CORE AND ITS MANUFACTURE

PROBLEM TO BE SOLVED: To prevent the deterioration of the magnetic performance of an iron core by forming the core integrally in a pair of semi-annular laminated core blocks to each other in an annular shape by laying joining sections of the blocks at both ends upon another. SOLUTION: A semi-annular core block 11 is formed by laminating a plurality of strip-like metal plates upon another by leaving straight-line sections at both ends so that joining sections 11b may be protruded alternately in the front end sections of the straight-line sections. A current transformer 16 is constituted of an iron core 3 constituted by joining a pair of core blocks 11 formed in the above-mentioned way with each other, by laying the joining sections 11b of the blocks 11 upon another and secondary windings 14 wound around insulating bobbins 15 respectively inserted into the straight-line sections of the blocks 11. Since the iron core 13 is constituted by joining the core blocks 11 with each other by laying the joining sections 11b formed in the front end sections of the straight-line sections of the blocks 11 upon another, the surface areas of the joining sections 11b of the blocks 11 increase. Therefore, the deterioration of the magnetic performance of the iron core 13 can be prevented by suppressing the increase of the magnetic resistance of the core 13.