Electrical inductive apparatus having serially interconnected coils

Claim 1

A power transformer comprising a shell-form type laminated magnetic core, a pancake-type winding structure disposed in inductive relationship with said laminated magnetic core, said winding structure having a plurality of winding groups which are physically separated by at least one other winding group, said separated winding groups each having first, second, third and fourth pancake-type coils, each of said coils having at least one conductor spirally wound for a plurality of coil turns, said conductor having a plurality of insulated strands, said insulated strands being grouped together to form a plurality of conductor groups with the conductor groups positioned at different radial positions in said conductor, each of said conductor groups having a plurality of insulated strands said conductor groups having said strands electrically connected together at the beginning position of the start turn of said coil and at the ending position of the finish turn of said coil, said second and third coils being electrically interconnected by a finish-finish connection, said first and second coils being electrically interconnected by a start-start connection, said third and fourth coils being electrically interconnected by a start-start connection, said finish-finish connection serially interconnecting said coils, said finish-fInish connection electrically connecting together all of the conductor groups from said second coil to the conductor groups from said third coil which are at radially opposite positions within the conductors when the conductors have an even number of conductor groups, said finish-finish connection electrically connecting together all of the conductor groups from said second coil, except a middle conductor group, to the conductor groups from said third coil which are at radially opposite positions within the conductors when the conductors have an odd number of conductor groups, said start-start connections electrically connecting together all of the conductor groups from one coil to the conductor groups from the other coil which are radially at the same position within the conductors.