Current transformer using a laminated toroidal core structure and a lead frame

A current transformer including a conductor, the electrical current passing through said conductor to be measured comprising:

• an insulating substrate having a first planar surface and an opposite second planar surface;
• a plurality of metallized coating conductive tracks formed on said first planar surface, each of said conductive tracks having a predetermined length with first and second ends;
• an annular magnetic core surrounding the conductor formed using thick film processing over said conductive tracks on said first planar surface comprised of a plurality of layers of ferrite material fired to form said magnetic core;
• insulating means electrically insulating said magnetic core from said conductive tracks;
• a plurality of metal conductors of predetermined length each having first and second ends and looping over said magnetic core and joined to said conductive tracks to form a toroidal coil around said magnetic core where the first end of each of said metal conductor being connected to the first end of a conductive track, the second end of said metal conductor being connected to the second end of an adjacent conductive track.

An inductive device formed on a nonconductive substrate comprising:

• a conductor having an electric current passing therethrough;
• a nonconductive substrate having a first planar surface and a second planar surface;
• a plurality of conductive tracks formed on said first planar surface by metallization, each of said conductive tracks having a predetermined length with first and second ends;
• layer of dielectric material on top of and in contact with the major portion of each of said conductive tracks, both the first and second ends extending beyond said dielectric layer;
• a toroidal magnetic core unit formed over said conductive tracks and said dielectric layer comprising a plurality of ring shaped layers of ferrite thick film material printed one upon another using a thick film screening process and surrounding said conductor;
• a core insulating means electrically insulating said toroidal magnetic core unit;
• a plurality of metal conductors of predetermined length each having first and second ends and placed over said toroidal magnetic core unit to form a toroidal coil, the first end of said metal conductors being connected to said first end of a different one of said conductive tracks, the second end of each of said metal conductors being connected to the second end of a different one of said conductive tracks;
• an electronics package consisting of a plurality of electronic components mounted on said second planar surface for generating an output signal;
• connection means for electrically connecting said toroidal coil to said electronics package.