Magnetic shielding construction for electric transformers

Claim 2

An electrical power transformer subject to overheating of the magnetic core laminations as a result of magnetic leakage flux entering the laminations perpendicular to the planes thereof comprising, in combination, a coil having primary and secondary transformer windings and a window therein, a closed magnetic core formed of a plurality of laminations of magnetic material disposed in parallel planes extending through said window in said coil, and a magnetic shield loop extending through said window and formed of a plurality of laminations of magnetic material overlying the planar surfaces of the laminations of said closed core around the entire contour of said closed core, the portion of said magnetic shield loop within said window being disposed between the planar surface of the laminations of said magnetic core and the inner periphery of said coil defining said window and comprising magnetic laminations having a width which is only a minor fraction of the width of said laminations of said closed core lying in planes perpendicular to the planes of said laminations of said closed magnetic core, whereby minimum leakage flux enters the laminations of said closed core perpendicular to the planar surfaces thereof and said magnetic shield loop carries part of the main flux.

Claim 3

An electrical power transformer as defined in claim 1 in which said magnetic core comprises oppositely disposed leg members connected to oppositely disposed yoke members and said coil surrounds one of said leg members and said magnetic shield loop comprises oppositely disposed leg members connected to oppositely disposed yoke members and each of said leg and yoke members comprises magnetic laminations in planes perpendicular to and overlying the planes of said laminations of the corresponding leg and yoke members of said closed magnetic core.

Claim 4

An electrical power transformer as defined in claim 1 in which said closed magnetic core comprises oppositely disposed leg members connected to oppositely disposed yoke members and is formed of flat stacked laminations and said coil surrounds one of said leg members and said magnetic shield loop comprises oppositely disposed leg members and oppositely disposed yoke members overlying the corresponding said leg and yoke members of said closed magnetic core and at least The portion of said magnetic shield loop within said window is formed of lamination strips of magnetic material lying in planes perpendicular to the planes of said flat stacked laminations.

Claim 5

An electrical transformer as defined in claim 3 wherein the portion of said magnetic shield loop within said window comprises a plurality of bundles of strips of magnetic material lying in planes perpendicular to the planes of said flat stacked laminations, said bundles being disposed side-by-side in a common plane parallel to the planes of said flat stacked laminations, the bundles at the center of said side-by-side bundles being of the greatest height where the leakage flux enters said flat stacked laminations at angles closest to the perpendicular and the height of said bundles decreasing progressively toward the end bundles wherein the leakage flux enters said flat stacked laminations at angles further removed from the vertical.

Claim 6

An electrical transformer comprising a coil having a window therein, a closed magnetic core having a winding leg portion formed of a plurality of core laminations of magnetic material in planes parallel to the coil axis extending through said coil window and yoke portions adjacent the axial ends of said coil, said core laminations extending the entire width of said winding leg portion, and a magnetic shield loop extending through said window and disposed between the inner periphery of said coil defining said window and the planar surfaces of the core laminations of said winding leg portion, at least the portion of said magnetic shield loop within said coil window comprising a plurality of side-by-side magnetic strip bundles intersected by a common plane parallel to the planes of said core laminations of said winding leg portion, each of said bundles comprising a plurality of magnetic strip laminations narrower than said core laminations and having a magnetic return path through the laminations of said yoke portions.

Claim 7

An electrical transformer comprising a coil having a window therein, a closed magnetic core having a winding leg portion formed of a plurality of core laminations of magnetic material in planes parallel to the coil axis extending through said coil window and yoke portions adjacent the axial ends of said coil, said core laminations extending the entire width of said winding leg portion, and a magnetic shield loop extending through said window and disposed between the inner periphery of said coil defining said window and the planar surfaces of the core laminations of said winding leg portion, at least the portion of said magnetic shield loop within said coil window comprising a plurality of side-by-side magnetic strip bundles intersected by a common plane parallel to the planes of said core laminations of said winding leg portion, each of said bundles comprising a plurality of magnetic strip laminations narrower than said core laminations and having a magnetic return path through the laminations of said yoke portions.

Claim 8

An electrical power transformer as defined in claim 3 in which said lamination strips of said magnetic shield loop are of the same material as said flat stacked laminations of said closed magnetic core and have a width which is only a minor fraction of the width of said flat stacked laminations of said closed core.

Claim 9

An electrical power transformer as defined in claim 3 wherein the window in said coil is circular and said lamination strips of said magnetic shield loop vary in width so that the edges thereof adjacent the inner periphery of said coil define an approximately arcuate surface complementary to said circular window.

Claim 10

An electrical power transformer subject to overheating of the laminations as a result of magnetic leakage flux entering the laminations perpendicular to the planes thereof comprising, in combination, a closed magnetic core formed of a plurality of laminations of magnetic material disposed in parallel planes and having opposed leg members joined by opposed yoke members, first and second magnetic shield loops each of which is formed of a plurality of laminations of magnetic material and having opposed leg members joined by opposed yoke members, the leg and yoke members of said first and second magnetic shield loops overlying the planar surfaces of the uppermost and lowermost of the laminations respectively of the corresponding leg members and yoke members of said closed core, and a coil having primary and secondary transformer windings and a window therein surrounding one leg portion of said closed core, the portion of each said magnetic shield loop within said window being disposed between said planar surface of said laminations of said one leg portion and the inner surface of said coil defining said window and comprising laminations in planes perpendicular to the planes of said laminations of said closed core, whereby minimum leakage flux enters the laminations of said closed core perpendicular to the planar surfaces thereof and said shield loops carry part of the main magNetic flux.

Claim 11

An electrical power transformer subject to overheating of the laminations as a result of magnetic leakage flux entering the laminations perpendicular to the planes thereof comprising, in combination, a closed magnetic core formed of a plurality of laminations of magnetic material disposed in parallel planes and having opposed leg members joined by opposed yoke members, first and second magnetic shield loops each of which is formed of a plurality of laminations of magnetic material and having opposed leg members joined by opposed yoke members, the leg and yoke members of said first and second magnetic shield loops overlying the planar surfaces of the uppermost and lowermost of the laminations respectively of the corresponding leg members and yoke members of said closed core, and a coil having primary and secondary transformer windings and a window therein surrounding one leg portion of said closed core, the portion of each said magnetic shield loop within said window being disposed between said planar surface of said laminations of said one leg portion and the inner surface of said coil defining said window and comprising laminations in planes perpendicular to the planes of said laminations of said closed core, whereby minimum leakage flux enters the laminations of said closed core perpendicular to the planar surfaces thereof and said shield loops carry part of the main magNetic flux.

Claim 12

An electrical power transformer in accordance with claim 8 wherein said laminations of said first and second magnetic shield loops are of the same material as said laminations of said closed core and have a width which is only a minor fraction of the width of said laminations of said closed magnetic core.

Claim 13

A shell type electrical power transformer subject to overheating of the magnetic core laminations as a result of magnetic leakage flux entering the laminations perpendicular to the planes thereof comprising, in combination, a coil having primary and secondary transformer windings and a window therein, a closed magnetic core formed of a plurality of laminations of magnetic material disposed in parallel planes and having a center tongue extending through said window and leg members disposed on opposite sides of said center tongue, and first and second magnetic shield loops in back-to-back relation each of which comprises a portion contiguous said center tongue extending through said window and another portion contiguous one of said leg members and formed of a plurality of laminations of magnetic material overlying the planar surfaces of the laminations of said magnetic core, the portion of each said magnetic shield loop within said window being disposed between the planar surfaces of laminations of said center tongue and the inner periphery of said coil defining said window and comprising magnetic laminations lying in planes perpendicular to the planes of said laminations of said magnetic core, whereby minimum leakage flux enters laminations of said center tongue perpendicular to the planar surfaces thereof and said first and second magnetic shield loops each carry part of the main flux.

Claim 14

A shell type electrical power transformer subject to overheating of the magnetic core laminations as a result of magnetic leakage flux entering the laminations perpendicular to the planes thereof comprising, in combination, a coil having primary and secondary transformer windings and a window therein, a closed magnetic core formed of a plurality of laminations of magnetic material disposed in parallel planes and having a center tongue extending through said window and leg members disposed on opposite sides of said center tongue, and first and second magnetic shield loops in back-to-back relation each of which comprises a portion contiguous said center tongue extending through said window and another portion contiguous one of said leg members and formed of a plurality of laminations of magnetic material overlying the planar surfaces of the laminations of said magnetic core, the portion of each said magnetic shield loop within said window being disposed between the planar surfaces of laminations of said center tongue and the inner periphery of said coil defining said window and comprising magnetic laminations lying in planes perpendicular to the planes of said laminations of said magnetic core, whereby minimum leakage flux enters laminations of said center tongue perpendicular to the planar surfaces thereof and said first and second magnetic shield loops each carry part of the main flux.

Claim 15

An electrical transformer as defined in claim 10 and including a third and a fourth shield loop in back-to-back relation to each other each of which has a portion contiguous said center tongue extending through said window and another portion adjacent one of said leg members formed of a plurality of laminations of magnetic material in underlying relation to the planar surfaces of the laminations of said magnetic core, the portion of each of said third and fourth shield loops continuous said center tongue comprising laminations perpendicular to the planes of the laminations of said center tongue.

Claim 16

An electrical transformer including a coil having a window therein, first and second closed magnetic cores having winding leg portions disposed back-to-back protruding through said window and also having yoke portions adjacent the axial ends of said coil, each of said closed magnetic cores being formed of core laminations of magnetic material in planes parallel to the axis of said coil window, first and second magnetic shield loops extending through said window between the inner periphery of said coil defining said window and the upper and lower surfaces of the winding leg portion of said first closed core, and third and fourth magnetic shield loops extending through said window between the inner periphery of said coil defining said window and the upper and lower surfaces of the winding leg portion of said second closed core, the portion of each magnetic shield loop within said window comprising a plurality of side-by-side bundles of magnetic strip laminations narrower than said core laminations disposed in overlying relation to the planar surface of an outer core lamination of the winding leg portion of the corresponding closed core.

Claim 17

An electrical transformer including a coil having a window therein, first and second closed magnetic cores having winding leg portions disposed back-to-back protruding through said window and also having yoke portions adjacent the axial ends of said coil, each of said closed magnetic cores being formed of core laminations of magnetic material in planes parallel to the axis of said coil window, first and second magnetic shield loops extending through said window between the inner periphery of said coil defining said window and the upper and lower surfaces of the winding leg portion of said first closed core, and third and fourth magnetic shield loops extending through said window between the inner periphery of said coil defining said window and the upper and lower surfaces of the winding leg portion of said second closed core, the portion of each magnetic shield loop within said window comprising a plurality of side-by-side bundles of magnetic strip laminations narrower than said core laminations disposed in overlying relation to the planar surface of an outer core lamination of the winding leg portion of the corresponding closed core.

Claim 18

An electrical transformer in accordance with claim 12 wherein said transformer is of the shell-type and said first and second closed cores are rectangular loops and said back-to-back winding leg portions form the core tongue of said shell-type transformer and wherein said first and third shield loops are disposed back-to-back in overlying relation to the upper surface of said core tongue and said second and fourth shield loops are disposed back-to-back and in underlying relation to the lower surface of said core tongue.