High-current electrical coil, and transformer construction including same
An electrical coil includes first and second electrically-conductive elements each of a thin, flat, annular configuration formed with a gap to define the turns of a 2-turn coil, and an electrically insulative element also of a thin, flat, annular configuration disposed coaxially between the two electrically-conductive elements and formed with a gap aligned with one end of each turn to permit the ends to be electrically connected together. Also described is a transformer having a secondary winding including a plurality of such 2-turn coils, and a primary winding of a plurality of double-coils each connected together at their mid-portions.
1. An electrical coil of at least two turns, comprising:
a first electrically-conductive element of a thin, flat, annular configuration formed with a gap to define a first turn of the coil;
a second electrically-conductive element also of a thin, flat, annular configuration and also formed with a gap to define a second turn of the coil, said second electrically-conductive element being disposed coaxially with respect to said first electrically-conductive element;
and electrical insulation between said first and second electrically-conductive elements insulating said first turn from said second turn except for one end of each turn to be electrically connected together;
characterized in that said insulation includes an electrically-insulative element also of a thin, flat, annular configuration disposed coaxially between said first and second electrically-conductive elements and formed with a gap aligned with said one end of each turn to permit said ends to be electrically connected together.
2. The electrical coil according to claim 1 , wherein the ends of the two turns to be electrically connected together are joined by soldering or welding.
3. The electrical coil according to claim 1 , wherein each of said first and second electrically-conductive elements is formed with first and second projecting end portions on opposite sides of the gap in the respective element; said first projecting end portions of the two electrically-conductive elements being angularly spaced from each other to define two terminals of the coil; said second projecting end portions of the two electrically-conductive elements being aligned with each other to define a center tap for said coil.
4. The electrical coil according to claim 1 , wherein the inner edge of one of said electrically-conductive elements is recessed at an intermediate portion thereof with respect to aligned intermediate portions of the other electrically-conductive element and of said electrically insulative element to increase the creepage distance for the conduction of electricity over said electrically insulative element from one electrically-conductive element to the other electrically-conductive element.
5. The electrical coil according to claim 4 , wherein the inner edge of the other of said electrically-conductive elements is similarly recessed at an intermediate portion thereof opposite to that of the recessed portion of said one electrically-conductive element.
6. The electrical coil according to claim 1 , wherein the inner edge of one of said electrically-conductive elements is recessed at two opposed intermediate portions thereof with respect to the aligned intermediate portions of the other of said electrically-conductive element and of said electrically insulated element to increase the creepage distance for the conduction of electricity over said electrically insulative from one electrically-conductive element to the other electrically-conductive element.
7. The electrical coil according to claim 6 , wherein the inner edge of the other of said electrically-conductive elements is similarly recessed at two intermediate portions thereof opposite to those of said recessed intermediate portions of the one electrically-conductive element.
8. The electrical coil according to claim 1 , wherein said first and second electrically-conductive elements, and said electrically insulative element, are of circular configuration.
9. The electrical coil according to claim 1 , wherein each of said first and second electrically-conductive elements is formed with only one projecting end portion on one side of its gap, the opposite side of the gap in the two electrically-conductive elements being electrically connected together such that said projecting end portions of the two electrically-conductive elements serve as two terminals of a 2-turn coil.
10. The electrical coil according to claim 9 , wherein the electrical coil includes two 2-turn coils assembled coaxially with each other, with a further electrically-insulative strip inbetween, and with one terminal of the two 2-turn coils aligned with each other aligned terminal, such as to define a 4-turn coil having two angularly spaced terminal, and a center-tab defined by said aligned terminals.