(12) United States Patent (10) Patent No.: US 6,535,100 B2. ForSS (45) Date of Patent: Mar. 18, 2003

Transcription

1 USOO653510OB2 (12) United State Patent (10) Patent No.: US 6,535,100 B2 ForSS (45) Date of Patent: Mar. 18, 2003 (54) INSULATED TRANSFORMER FOIL 4.222,023 A 9/1980 Beech /209 WINDINGS WITH BREAKOUTS AND 4,376,904 A 3/1983 Horrigan /208 METHODS FOR FORMING THE SAME 4,395,693 7/1983 Marinecu /223 5,274,904 A 1/1994 Proie /200 & 8 5,805,045 * 9/1998 Henninger /192 (75) Inventor: Börje Ander For, Taby (SE) 6,087,922 A 7/2000 Smith /223 (73) Aignee: Powerware Corporation, Raleigh, NC (US) FOREIGN PATENT DOCUMENTS (*) Notice: Subject to any diclaimer, the term of thi wo woo. A '' HO1F/41/04 patent i extended or adjuted under 35 U.S.C. 154(b) by 116 day. OTHER PUBLICATIONS (21) Appl. No.: 09/751,035 International Search Report for PCT/US01/08829 dated Sep. (22) Filed: Dec. 29, , (65) Prior Publication Data * cited by examiner US 2002/ A1 May 16, 2002 Related U.S. Application Data Primary Examiner Anh Mai (60) Proviional application No. 60/197,242, filed on Apr. 14, (74) Attorney, Agent, or Firm- Myer Bigel Sibley & Sajovec (51) Int. Cl."... H01F 27/28 (57) ABSTRACT (52) U.S. Cl /225; 336/200; 336/223; 29/602.1 Winding aemblie for ue in tranformer include one or (58) Field of Search /223, 200, more foil trip and inulation cover arranged to provide 336/225, 232; 29/602.1, 605, 607 electrically inulated winding and breakout portion. The winding aemblie may be contructed So a to meet (56) Reference Cited creepage ditance and other requirement in a margin free coil deign tranformer. U.S. PATENT DOCUMENTS 4,151,640 A 5/1979 McDermott et al / Claim, 16 Drawing Sheet (S N3 2

2 U.S. Patent Mar. 18, Sheet 1 of 16 US 6,535,100 B

3 U.S. Patent Mar. 18, Sheet 2 of 16 US 6,535,100 B2 f S. S. S. S. 7 X777 NSN N2 4ZZYZZZZ (4342(Z2& Six-SSZZ, Zzz S. (% 2N. 2 Ya N. Ya NYaYa N N Ya S pet ev / / / S. Sp N u S. Y S O Life

4 U.S. Patent Mar. 18, 2003 Sheet 3 of 16 US 6,535,100 B2 io 2B C=CAL A

5 U.S. Patent Mar. 18, Sheet 4 of 16 US 6,535,100 B

6 U.S. Patent Mar. 18, 2003 Sheet 5 of 16 US 6,535,100 B2 O f en Z/ / / /? 63 77,777/ y L. 772 NYNNNNNNNNNNNNN NZ Z2nS4 Z/Z-> (7/YYYY N S y N &

7 U.S. Patent Mar. 18, Sheet 6 of 16 US 6,535,100 B2 AW FIG 2E

8 U.S. Patent Mar. 18, 2003 Sheet 7 of 16 US 6,535,100 B2

9 U.S. Patent Mar. 18, 2003 Sheet 8 of 16 US 6,535,100 B2 22 ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ 4. Z / A2ZZYZZY/ SN 272-r-. S

10 U.S. Patent Mar. 18, 2003 Sheet 9 of 16 US 6,535,100 B2

11 U.S. Patent Mar. 18, 2003 Sheet 10 of 16 US 6,535,100 B2

12 U.S. Patent Mar. 18, 2003 Sheet 11 of 16 US 6,535,100 B2 AG 4B D 432B

13 U.S. Patent Mar. 18, Sheet 12 of 16 US 6,535,100 B2

14 U.S. Patent Mar. 18, 2003 Sheet 13 of 16 US 6,535,100 B2, Y/a11/22 ait SSS ed 27 8 FIG 7.

15 U.S. Patent Mar. 18, Sheet 14 of 16 US 6,535,100 B2 40A / 40 FIG 84. FIG 8B FIG 80.

16 U.S. Patent Mar. 18, 2003 Sheet 15 of 16 US 6,535,100 B B 50B FIG 94. FIG 9B

17 U.S. Patent Mar. 18, Sheet 16 of 16 US 6,535,100 B2 S G

18 1 INSULATED TRANSFORMER FOIL WINDINGS WITH BREAKOUTS AND METHODS FOR FORMING THE SAME RELATED APPLICATION Thi application claim the benefit of U.S. Proviional Patent Application Ser. No. 60/197,242, filed Apr. 14, 2000, the dicloure of which i hereby incorporated herein by reference in it entirety. FIELD OF THE INVENTION The preent invention relate to tranformer winding and, more particularly, to inulated tranformer winding having inulated breakout and method for forming the SC. BACKGROUND OF THE INVENTION Certain Safety regulation relating to inulation between tranformer winding require that the tranformer be deigned Such that a tipulated winding creepage ditance i allowed without contact between repective winding and Such that a tipulated clearance between repective winding i provided. The creepage ditance i the hortet ditance between adjacent conductor following a Surface without going through inulation (rather, the ditance i meaured a going around and/or along inulation). Additionally, regu lation may require certain minimum air ditance and ditance through inulation between winding. It i deir able to meet Such regulation while nonethele reducing the cot and ize of the tranformer. One method that ha been ued to meet the foregoing regulation i to provide Subtantial margin a illutrated by the tranformer 10 a hown in FIG. 5, which may be referred to a a margin coil deign. The tranformer 10 ha a core 12 with a core center leg 12A and oppoed end leg 12B. The tranformer 10 alo include a firt, foil winding 30 that i wound about the center leg 12A, and a Second, wire winding 20 that i wound about the firt winding 30. Alternatively, the econd winding 20 may be a foil winding alo or the poition of the winding 20 and 30 may be revered. The core 12 may include an inulating cover layer to prevent direct electrical contact with either of the wind ing 20, 30. Inulation layer 14, 16, 18 (which may be reinforced) are inerted between the center leg 12A and the firt winding 30, between the firt winding 30 and the econd winding, and between the Second winding 20 and the end leg 12B of the core 12. In order to meet the above-mentioned required creepage ditance and clearance (RCDC), primary margin M1 and M2 are provided above and below the winding 30 and econdary margin P1 and P2 are provided above and below the winding 20. The required margin may depend on the Voltage cla of the tranformer, the cla of the inulation employed and/or other parameter. Typically, the Sum of the hortet primary and econdary margin M1, M2, P1, P2 hould be greater than or equal to the RCDC. That i (regarding the core a electrically conductive), the margin and the RCDC hould be related a follow: M1-P12 RCDC M2--P22RCDC M1-P22RCDC M2--P12 RCDC The combined width of the winding 20 and the margin P1, P2 and the combined width of the winding 30 and the margin M1, M2 are each limited by the length L of the core US 6,535,100 B center leg 12A. The width of the margin M1, M2, P1, P2 may be ubtantial a compared to the width of the wind ing 20, 30. Hence, a large portion of the available winding width may be conumed by the margin M1, M2, P1, P2, thereby neceitating the proviion of a larger core and, accordingly, a larger tranformer. In order to provide better utilization of the available winding Space, a tranformer a decribed above may be formed without margin, i.e., with the width of the wind ing being of nearly the ame dimenion a the length of the core center leg 12A. An exemplary margin free coil tran former 10', which may be referred to a a margin free coil deign, i hown in FIGS. 6 and 7. The tranformer 10' ha winding 20', 30', reinforced inulating layer 14, 16', 18", and a core 12" having a center leg 12A. Each winding 20', 30' ha a breakout on each end thereof. The breakout 34 of the foil winding 30" are hown in cro-ection in FIG. 7. Notably, mean mut be provided in the margin free coil tranformer 10' to addre the creepage ditance and clear ance regulation dicued above. One method of Solving thi problem i to inulate the firt (foil) winding 30' and it breakout in their entiretie Such that the requirement for creepage ditance and clearance, a well a ditance through inulation, are met by the inulation about the firt winding 30' alone. For example, a winding foil trip 40 a hown in FIG. 8A may be provided. The trip 40 ha a width that i approxi mately the ame a the length of the center leg 12A. The trip 40 i covered with an inulator 40A and then folded once to create a breakout 42 of the ame width a the Strip 40, a hown in FIG. 8B. However, in many tranformer the width of the center leg 12A i ubtantially le than it length and the breakout hould be cloe to the width of the core. For example, in ferrite EE-core the length to width ratio of the center leg i typically approximately two. To achieve the appropriate breakout width, the breakout 42 i folded again to form a narrow breakout 44 a hown in FIG. 8C. The breakout 44 correpond to one of the breakout 34 (ee FIG. 7), for example. Notably, thi method of folding create Subtantial increae in thickness in certain area a a reult of the Stacking of four layer of foil, a well a the inulation, on each layer. Additionally, the inulation may be damaged by the folding Step. If hole are formed in the inulation, the tranformer may no longer meet the creepage ditance, clearance and ditance through inulation require ment. The exitence of Small hole in the inulation may be hard to detect. According to a further prior art method, a triple inulated wire which i approved by Safety agencie for ue where reinforced inulation i required may be ued for the wind ing 20' without additional inulation. The wire in the wind ing 20' itelf provide the required inulation and there are therefore no requirement on the inulation of the winding 30' other than functional requirement. Thi method uffer from Several drawback in practice. AS an alternative to uing a folded foil winding, the winding 30' may be formed uing an inulated winding foil trip 50 and a joined breakout 52 a hown in FIGS. 9A and 9B. The breakout 52 correpond to one of the breakout 34 (ee FIG. 7). The breakout 52 and the trip 50 are each covered with an inulator 50A, 52A except on end portion 50B, 52B. The end portion 50B, 52B are expoed to allow electrical contact between the trip 50 and the breakout 52 over mot of the width of the trip 50. According to ome prior art method, one or more Supplemental inulation member may be provided covering the expoed portion of the winding foil trip and the breakout. However, uch

19 3 contruction may not in fact provide a true margin free coil deign while Still meeting applicable Safety requirement and, accordingly, margin are till required. SUMMARY OF THE INVENTION The invention i directed to winding aemblie for ue in tranformer and method for forming the ame. The wind ing aemblie include one or more foil Strip and inulation cover arranged to provide electrically inulated winding and breakout or breakout tap portion. The winding aem blie may be contructed So a to meet the aforementioned creepage ditance and other requirement. According to method embodiment of the invention for forming an inulated winding aembly for an electrical tranformer, an integral foil Strip having a lengthwie axi i provided. The foil Strip include a winding portion and a breakout portion extending from the winding portion along the lengthwie axi. The breakout portion i folded about the winding portion to form a fold between the breakout portion and the winding portion. Thereafter, an inulation cover i Secured to the foil Strip. The Step of Securing an inulation cover to the foil Strip may include Securing a firt inulation cover to the winding portion and Securing a Second inulation cover to the brea kout portion Such that a contact portion of the foil Strip adjacent the fold remain expoed. The method further include Securing a Supplemental inulation cover over the contact portion. The Second inulation cover may be over lapped over the winding portion by at leat a precribed minimum creepage ditance. According to further method embodiment of the inven tion for forming an inulated winding aembly for an electrical tranformer, a foil winding Strip having a length wie axi and a firt inulation cover covering a portion of the winding Strip are provided. An expoed portion of the winding Strip extend beyond the firt inulation cover along the lengthwie axi of the winding Strip. A foil breakout Strip having a lengthwie axi and a Second inulation cover covering a portion of the breakout Strip i alo provided. An expoed portion of the breakout Strip extend beyond the Second inulation cover along the lengthwie axi of the breakout Strip. The breakout Strip i placed on the winding Strip Such that the breakout Strip expoed portion engage the winding Strip expoed portion and the Second inulation cover overlap the winding Strip. The Second inulation cover may overlap the winding Strip by at leat a precribed minimum creepage ditance. A Supplemental inulation cover may be Secured over the breakout Strip expoed portion. According to other method embodiment of the invention for forming an inulated winding aembly for an electrical tranformer, a foil winding portion and a foil breakout portion adjoining the winding portion are provided. The breakout portion overlap and extend at an angle with repect to the winding portion. A Supplemental inulation cover i wrapped about and between the winding portion and the breakout portion Such that the Supplemental inulation cover include a firt panel covering the breakout portion, a Second panel covering a rear Surface of the winding portion, and a third panel dipoed between the winding portion and the breakout portion. According to other method embodiment of the invention for forming an inulated winding aembly for an electrical tranformer, a foil winding Strip and a foil breakout Strip are provided. The foil winding Strip ha a lengthwie axi and a firt inulation cover covering a portion of the winding Strip. US 6,535,100 B An expoed portion of the winding Strip extend beyond the firt inulation cover along the lengthwie axi of the wind ing Strip. The foil breakout Strip ha a lengthwie axi and a Second inulation cover covering a portion of the breakout Strip. An expoed portion of the breakout Strip extend beyond the Second inulation cover along the lengthwie axi of the breakout Strip. The breakout Strip i placed on the winding Strip Such that the breakout Strip expoed portion engage the winding Strip expoed portion and the breakout Strip and the winding Strip form an inner corner therebe tween. Abellow cover i placed over the breakout Strip and the winding Strip Such that a firt leg portion of the bellow cover overlap the firt inulation cover, a Second leg portion of the bellow cover Overlap the Second inulation cover, and a bellow ection of the bellow cover extend acro the inner corner and join the firt and Second leg portion. The method may further include placing an L-haped cover over the breakout Strip and the winding Strip Such that the L-haped cover overlap each of the firt and Second inu lation cover and the firt and Second leg portion. According to further embodiment of the invention, a winding aembly for ue in a tranformer include a foil Strip. The foil Strip include a winding portion and a brea kout portion integral with the winding portion and joined to the winding portion along a fold. A firt inulation cover cover a portion of the winding portion. A Second inulation cover cover a portion of the breakout portion. A Supple mental inulation cover cover each of the winding portion and the breakout portion. According to further embodiment of the invention, a winding aembly for ue in a tranformer include a foil winding Strip having a lengthwie axi and a firt inulation cover covering a portion of the winding trip. An expoed portion of the winding Strip extend beyond the firt inu lation cover along the lengthwie axi of the winding Strip. The winding aembly further include a foil breakout trip having a lengthwie axi. A Second inulation cover cover a portion of the breakout Strip. An expoed portion of the breakout Strip extend beyond the Second inulation cover along the lengthwie axi of the breakout Strip. The breakout Strip expoed portion engage the winding Strip expoed portion and the Second inulation cover overlap the winding Strip. According to embodiment of the invention, a winding aembly for ue in an electrical tranformer include a foil winding portion and a foil breakout portion adjoining the winding portion. The breakout portion overlaps and extend at an angle with repect to the winding portion. A Supple mental inulation cover i wrapped about and between the winding portion and the breakout portion. The Supplemental inulation cover include a firt panel covering the breakout portion, a Second panel covering a rear Surface of the winding portion, and a third panel dipoed between the winding portion and the breakout portion. According to further embodiment of the invention, a winding aembly for ue in a tranformer include a foil winding Strip and a foil breakout Strip. The foil winding Strip ha a lengthwie axi. A firt inulation cover cover a portion of the winding Strip. An expoed portion of the winding Strip extend beyond the firt inulation cover along the lengthwie axi of the winding trip. The foil breakout Strip ha a lengthwie axi. A Second inulation cover cover a portion of the breakout Strip. An expoed portion of the breakout Strip extend beyond the Second inulation cover along the lengthwie axi of the breakout Strip. The breakout Strip expoed portion engage the winding Strip expoed portion and the breakout Strip and the winding Strip form an

20 S inner corner therebetween. A bellow cover cover the breakout trip and the winding trip. The bellow cover include a firt leg portion overlapping the firt inulation cover, a Second leg portion overlapping the Second inula tion cover, and a bellow Section extending acro the inner corner and joining the firt and Second leg portion. The winding aembly may further include an L-haped cover covering the breakout Strip and the winding Strip, the L-haped cover overlapping each of the firt and Second inulation cover and the firt and Second leg portion. Object of the invention will be appreciated by thoe of ordinary kill in the art from a reading of the Figure and the detailed decription of the preferred embodiment which follow, Such decription being merely illutrative of the invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A i a front view of a winding aembly according to the preent invention; FIG. 1B i a cro-ectional view of the winding aembly of FIG. 1A taken along the line 1B-1B of FIG. 1A; FIG. 1C i a cro-ectional view of the winding aembly of FIG. 1A taken along the line 1C-1C of FIG. 1A; FIG. 1D i a cro-ectional view of the winding aembly of FIG. 1A taken along the line 1D-1D of FIG. 1A; FIG. 1E i a front view of a foil trip for forming the winding aembly of FIG. 1A; FIG. 1F i a front view of the foil trip of FIG. 1E in a folded poition; FIG. 1G i a left end view of the foil trip of FIG. 1F in the folded poition; FIG. 1H i a front view of the foil trip of FIG. 1F in the folded poition, and further including inulation cover, FIG. 1I i a left end view of the foil trip and inulation cover of FIG. 1H: FIG. 2A i a front view of a winding aembly according to a further embodiment of the preent invention; FIG.2B i a cro-ectional view of the winding aembly of FIG. 2A taken along the line 2B-2B of FIG. 2A; FIG. 2C i a front view of a foil trip for forming the winding aembly of FIG. 2A; FIG. 2D i a front view of the foil trip of FIG. 2C in a firt folded poition; FIG. 2E i a front view of the foil trip of FIG. 2D in a Second folded poition; FIG. 2F i a front view of the foil trip of FIG. 2E in the Second folded poition, and further including inulation covers, FIG. 2G i a left end view of the foil trip and inulation cover of FIG. 2F, FIG. 3A i a front view of a winding aembly according to a further embodiment of the preent invention; FIG. 3B i a cro-ectional view of the winding aembly of FIG. 3A taken along the line 3B-3B of FIG. 3A; FIG. 3C i an exploded view of a winding trip and a breakout trip for forming the winding aembly of FIG.3A; FIG. 3D i a front view of the winding trip and the breakout trip of FIG. 3C in a joined poition; FIG.3E i a cro-ectional view of the winding trip and breakout trip of FIG. 3D taken along the line 3E-3E of FIG. 3D; FIG. 4A i a front view of a winding aembly according to a further embodiment of the preent invention; US 6,535,100 B FIG. 4B i an exploded view of a winding trip and a breakout trip for forming the winding aembly of FIG. 4A; FIG. 5 i a Schematic, cro-ectional view of a margin coil deign tranformer; FIG. 6 i a Schematic, cro-ectional view of a margin free coil deign tranformer; FIG. 7 i a chematic, cro-ectional view of the tran former of FIG. 6 taken along the line 7-7 of FIG. 6; FIG. 8A i a front view of an inulated foil trip for forming a winding aembly according to the prior art; FIG.8B i a front view of the winding trip of FIG. 8A in a firt folded poition; FIG. 8C i a front view of an inulated winding aembly according to the prior art having a folded breakout; FIG. 9A i a front view of an inulated winding aembly according to the prior art having a joined breakout; FIG.9B i a left end view of the winding aembly of FIG. 9A; FIG. 10A i a front view of a winding aembly according to a further embodiment of the preent invention; FIG. 10B i a front view of a winding trip and a breakout trip for forming the winding aembly of FIG. 10A in a joined poition; FIG. 10C i a front view of the winding trip and breakout trip of FIG. 10B with inulation cover mounted thereon; and FIG. 10D i a front view of the winding trip, breakout trip, and inulation cover of FIG. 10C with a bellow cover mounted thereon. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention now will be decribed more fully herein after with reference to the accompanying drawing, in which preferred embodiment of the invention are hown. Thi invention may, however, be embodied in many different form and hould not be contrued a limited to the embodi ment Set forth herein; rather, thee embodiment are pro Vided So that thi dicloure will be thorough and complete, and will fully convey the cope of the invention to thoe killed in the art. Like number refer to like element throughout. The thicknee of layer and relative dimen Sion of panel, fold and SpaceS a illutrated in the Figure may be exaggerated for clarity. With reference to FIGS. 1A-1D, an inulated foil winding aembly 190 a hown therein may be employed in a tranformer a decribed above or any other Suitable tran former to provide a reduced margin or a margin free coil deign tranformer a hown in FIGS. 6 and 7. A ued herein, "margin free coil deign refer to tranformer having only nominal pacing between the edge of the winding and the core. The invention may be employed to allow reduced margin that may not be commonly referred to a margin free, a well. For the purpoe of explanation, the winding aembly 190 i decribed with reference to the tranformer 10'. A will be appreciated from the decription herein, the winding aem bly 190 may be ubtituted for the winding 30' of the tranformer 10'. The tranformer incorporating the winding aembly 190 may be otherwie formed and contructed in conventional or other Suitable manner. The winding aem bly 190 and other winding aemblie according to the preent invention may be incorporated into tranformer of other type and deign.

21 7 The winding aembly 190 include a winding portion 192 and a folded breakout 194 which may be uitably ized, configured and inulated to meet the aforedecribed creep age ditance, clearance and ditance through inulation requirement. For mot application, the winding aembly 190 will alo have a econd breakout on the end of the winding portion 192 oppoite the breakout 194. The econd breakout i preferably a mirror image or an inverted mirror image of the breakout 194. The contruction of the winding aembly 190 may be better appreciated with reference to FIGS. 1A-1I and the decription of the preferred method for forming the winding aembly 190 that follow. With reference to FIG.1E, the winding aembly 190 may be formed uing a foil Strip 110 having a lengthwie axi AL-AL and a widthwie axi AW-AW extending Sub Stantially perpendicular to the lengthwie axi AL-AL. The foil trip 110 i preferably formed of a unitary foil of flexible, electrically conductive material. More preferably, the foil trip 110 i formed of a foil of copper. Preferably, the foil trip 110 ha a ubtantially uniform thickne. The thickne and other dimenion of the foil will vary with the deign and rating of the tranformer. Preferably, the foil ha a width to thickne ratio of at leat 1, and more preferably of between about 10 and 500. The invention i particularly advantageou for foil having a thickne of between about 0.1 and 1.0 mm. The length of the foil trip 110 will depend on the deired length of the breakout 194, the econd, oppoite breakout, and the winding portion 192. The foil trip 110 may be cut from a larger piece of foil and/or a portion of the original foil Strip may be cut away to provide the illutrated Shape. For example, a cut-out 111 a dicued below may be formed by cutting and removing a portion of the foil trip. The foil trip 110 include a winding portion 112 having a width B which i preferably lightly le than the length L' of the core center leg 12A of the aociated tranformer 10'. More preferably, the width B i between about 0.5 and 2 mm le than the length L' of the core center leg 12A. The foil trip 110 alo include a breakout portion 114 having a reduced width C a compared to the width B of the winding portion 112. Preferably, the width C i the ame a or le than the width W" of the core center leg 12A. The winding portion 112 and the breakout portion 114 have ubtantially collinear lower edge 112A and 114A extending parallel to the axi AL-AL. The upper edge 112B and 114B of the winding portion 112 and the breakout portion 114 alo extend parallel to the axi AL-AL, but are laterally paced apart from one another along the tranvere axi AW-AW. A loped edge 113 join the edge 112B and 114B and, along with the edge 114B, define a cut-out 111 in the winding trip 110. Preferably, the edge 113 form an angle of between about 45 and 90 degree with the edge 114B. The foil trip 110, while till uninulated, i folded about a fold line 150A (indicated in dahed line in FIG. 1C) to form a fold 150 a hown in FIG.1F. Preferably, the fold 150 form an angle of about 45 degree with repect to the axi AL-AL. In thi manner, the breakout portion 114 i re-poitioned Such that the length thereof extend Subtan tially parallel to the axi AW-AW and ubtantially per pendicular to the axi AL-AL. Becaue the foil trip 110 i not inulated, the fold 150 can be flattened uing force without damaging inulation. Preferably, any burr and/or any other defect are removed before applying inulation a decribed below. After the foil trip 110 i folded and finihed a decribed above, inulation cover 132 and 134 are applied over the US 6,535,100 B foil trip 110 uch that portion of the winding portion 112 and the breakout portion 114 are covered on their front and rear Side and on their lengthwie edge a hown in FIGS. 1H and 1I. The inulation cover 134 overlap the portion 112C a ditance E. The inulation cover 132, 134 are preferably provided in the form of a coherent web and are wrapped about the foil trip 110. Preferably, the inulation cover 132 overlap itelf on the rear urface of the winding portion 112 a ditance N (ee FIG. 1C). The inulation cover 132,134 may be held in place by gla fiber tape or backing adheive, for example. The inulation covers 132, 134 are electrically inulative. Preferably, the inulation cover 132,134 are flame reitant and relatively thermally conductive. Suitable inulation cover material include NomexTM inulation paper available from DuPont Corpora tion. Adjacent portion 112C and 114C of the winding portion 112 and the breakout portion 114, repectively, remain expoed and uncovered by the inulation cover 132,134. A upplemental inulation cover 140 i folded about the foil trip 110 a hown in FIGS. 1A-1D to fully cover and inulate the previouly expoed portion 112C, 114C. The cover 140 include a firt panel 142 covering the forwardly facing Surface of the winding portion 112 and the breakout portion 114, a econd panel 144 joined to the firt panel 142 along a fold 143 and covering the rearwardly facing Surface of the portion 112, 114, and a third panel 146 joined to the econd panel 144 along a fold 145. The third panel 146 i inerted between the forwardly facing Surface of the winding portion 112 and the rearwardly facing Surface of the brea kout portion 114. Left and right marginal portion 140A and 140B of the inulation cover 140 are dipoed on oppoed ide of the breakout 194. Preferably, the inulation cover 140 i formed of the ame type of material a decribed above for the inulation cover 132,134 and may be applied and Secured in the Same manner. The inulation cover 134 overlap the portion 112C a ditance E. The panel 142 overlap the inulation cover 134 a ditance F. Each of the panel 142, 144, 146 ha a right marginal portion that overlap the inulation cover 132 a ditance H and a left marginal portion that extend left wardly beyond the fold 150 a ditance G. The panel 146 overlap the winding portion 112 a ditance I. In thi manner, the entirety of the foil trip 110 except a breakout contact portion 114D (and any other intended breakout contact portion) i covered by and enveloped within the inulation cover 132, 134, 140. By appropriate Selection of the dimenion of the inulation cover 132, 134, 140, the creepage ditance, clearance and ditance through inulation requirement may be met. Preferably, each of the following ditance (allowing for manufacturing tolerance) are equal to or greater than the required or deired creepage ditance and clearance: (1) ditance E (FIG. H) from the upper edge 112B of the winding portion 112 down to the lower edge of the inulation cover 134; (2) ditance F (FIG. 1A) from the upper edge of the inulation panel 142 to the lower edge of the inulation cover 134; (3) ditance G (FIG. 1A) from the left edge of the breakout portion 114 to the left edge of the panel 142, 144 and 146; (4) ditance H (FIG. 1A) from the left edge of the inulation cover 132 to the right edge of the panel 142, 144 and 146; and (5) ditance I (FIG. 1B)-from the upper edge 112B of the winding portion 112 to the lower edge of the panel 146.

22 9 The winding portion 192 of the winding aembly 190 may be wound about the center leg 12A with the breakout() 194 extending along an axi parallel to the axi of the center leg 12A. Becaue the inulation cover 132, 134, 140 Securely and completely envelope the critical portion of the foil trip 110, the core 12" and the center leg 12A may be ized and configured to provide a margin free (or reduced margin) coil deign. The method by which the winding aembly 190 i formed ubtantially reduce the rik that any of the inulation cover 132, 134, 140 may be damaged or breached during contruction of the winding aembly 190, and alo allow the winding aembly 190 to be formed without undue thickne. Becaue the foil trip 110 i not inulated, the fold 150 can be flattened uing force without damaging inulation. Therefore, the method may be ued effectively on thick and hard foil. With reference to FIGS. 2A and 2B, a winding aembly 290 according to a further embodiment of the preent invention i hown therein. The winding aembly 290 include a winding portion 292 and a folded breakout 294. The winding aembly 290 may include a econd breakout on the end of the winding portion 292 oppoite the breakout 294. The contruction of the winding aembly 290 may be better appreciated from FIGS. 2A-2G and the decription of a method for forming the winding aembly 290 that fol low. With reference to FIG. 2C, a foil trip 210 i provided. The foil trip 210 i the ame a the foil trip 110 except that the trip 210 i haped differently. The trip 210 ha a lengthwie axi AL-AL" and a widthwie axi AW-AW perpendicular thereto. The trip 210 include a winding portion 212 and a breakout portion 214. Preferably, the winding portion 212 and the breakout portion 214 have the ame width B'. The breakout portion 214 include a lower Section or panel 214E, an upper Section or panel 214F, and a connecting Section 214G connecting the lower panel 214E to the winding portion. Preferably, the panel 214E and 214F have the ame width C". The upper edge of the connecting portion 214G and oppoing, loped edge 213, 216 define a cut-out 211. Preferably, each of the edge 213 and 216 form an angle of between about 45 and 90 degree with repect to the lengthwie axi AL-AL' of the trip 210. The panel 214F i folded down about a fold line 252A(ee FIG. 2C) and onto the panel 214E to form a fold 252 a hown in FIG. 2D. The connecting portion 214G i alo folded about a fold line 250A (ee FIG. 2D) to form a fold 250 (ee FIG. 2E). Preferably, the fold 250 form an angle of about 45 degree with repect to each of the axe AL'-AL' and AW-AW'. Each of the fold 250, 252 may be forcibly flattened and deburred or otherwie finihed in the manner decribed above with regard to the foil trip 110. Thereafter, inulation cover 232 and 234 correponding to the inulation cover 132 and 134, repectively, are wrapped about the trip 210 in the manner decribed above with regard to the winding aembly 190 and a hown in FIGS. 2F and 2G. However, in the cae of the trip 210, the inulation cover 234 i wrapped around both of the Super impoed foil panel 214E, 214F. A Supplemental inulation cover 240 correponding to the Supplemental inulation cover 140 i wrapped about the folded trip 210 and the cover 232,234 in the ame manner a decribed above with regard to the inulation cover 140 and a hown in FIGS. 2A and 2B. The cro-ectional view of FIGS. 1C and 1D likewie illutrate the configuration of the winding aembly 290 at correponding cro-ection location. US 6,535,100 B The dimenion B", E, F, G, H' and I' correpond to the dimenion B, E, F, G, H and I, repectively, of the winding aembly 190. Preferably, each of the ditance B", C, E, F, G", H' and I" i equal to or greater than the required or deired creepage ditance and clearance. For ome application, the winding aembly 290 may be preferred over the winding aembly 190 becaue, except for the connecting portion 214G, the breakout 294 ha the ame conductor area a the winding portion 292. A a reult, the total winding reitance of the winding aembly 290 may be reduced a compared to that of the winding aembly 190. With reference to FIGS. 3A and 3B, a winding aembly 390 according to a further embodiment of the preent invention i hown therein. The winding aembly 390 include a winding portion 392 and a joined breakout 394. The winding aembly 390 may include a econd breakout on the end of the winding portion 392 oppoite the breakout 394. The breakout 394 may be relocated to a more central poition along the winding portion to Serve a a breakout tap. The contruction of the winding aembly 390 may be better appreciated from FIGS. 3A-3E and the decription of a method for forming the winding aembly 390 that follow. With reference to FIG. 3C, a winding trip 312 and a dicrete, Separately formed breakout Strip 314 are provided. The trip 312 and 314 are each formed of the ame material a decribed above with regard to the foil trip 110. The breakout trip 314 ha a width C" preferably of the ame relative dimenion a decribed above with regard to the width C of FIG. 1E. The winding trip 312 ha a lengthwie axi AL"-AL" and a perpendicular widthwie axi AW"- AW". The winding trip 312 ha a width B" preferably of the ame relative dimenion a the width B of FIG. 1E. An inulation cover 334 i wrapped fully around the breakout trip 314. The inulation cover 334 i ized and configured Such that an upper, expoed portion 314D of the breakout trip 314 extend above the inulation cover 334 and a lower, expoed portion 314C of the breakout trip 314 extend below the inulation cover 334. The inulation cover 334 i preferably formed of the material and ecured in the manner decribed above with regard to the inulation cover 134. An inulation cover 332 and an inulation cover 333 each fully Surround the winding Strip 312 Such that an expoed, intermediate portion 312C of the winding trip 312 i poitioned between the inulation cover 332 and 333 along the axi AL"-AL". The inulation cover 332 and 333 are preferably formed of the ame material and Secured in the Same manner a the inulation cover 132. With reference to FIGS. 3D and 3E, the breakout trip 314 i poitioned againt the winding Strip 312 Such that the portion 314C contact the portion 312C and a lower portion of the inulation cover 334 overlap the portion 312C a ditance E". Preferably, the lower edge 314A of the breakout trip 314 i aligned with the lower edge 312A of the winding trip 312 a hown. The portion 314C of the breakout trip 314 i poitioned fully between the adjacent edge of the inulation cover 332 and 333. Thereafter, a upplemental inulation cover 340 corre ponding to the Supplemental inulation cover 140 i wrapped around and between the winding Strip 312 and the breakout trip 314 a hown in FIGS. 3A and 3B and in the manner decribed above with repect to the Supplemental inulation cover 140. The cro-ectional view of FIGS. 1C and 1D likewie illutrate the configuration of the winding aembly 390 at correponding cro-ection location. The dimenion B", C", E", F", G", H" and I" correpond to the dimenion B, C, E, F, G, H and I, repectively, of the

23 11 winding aembly 190. Preferably, each of the ditance B", C", E", F", G", H" and I" i equal to or greater than the required or deired creepage ditance and clearance. With reference to FIG. 4A, a winding aembly 490 according to a further embodiment of the preent invention i hown therein. The winding aembly 490 include a winding portion 492 and a joined breakout 494. The winding aembly 490 may include a econd breakout on the end of the winding portion 492 oppoite the breakout 494. The contruction of the winding aembly 490 may be better appreciated from FIGS. 4A and 4B and the decription of a method for forming the winding aembly 490 that follow. A winding trip 412 and a breakout trip 414 are provided. The breakout trip 414 i the ame a the breakout trip 314 and ha an inulation cover 434 correponding to the inu lation cover 334 wrapped thereabout and ecured thereto. The winding trip 412 i the ame a the winding trip 312 and ha inulation cover 432 and 433 wrapped thereabout and ecured thereto. The inulation cover 433 correpond to the inulation cover 333. The inulation cover 432 correpond to the inulation cover 332 except a follow. The inulation cover 432 ha oppoed cuff 432A and 432B which define an intermediate, lengthwie extending expoed portion 412D of the winding trip 412 therebetween. Preferably, the inulation cover 432 fully cover the revere ide of the winding trip 412. Alternatively, an opening may be provided in the inulation cover 432 on the revere ide a well whereby an expoed portion correponding to the expoed portion 412D i preent on the revere ide of the winding Strip 412. The breakout trip 414 i mounted on the winding trip 412 in the ame manner a decribed above for mounting the breakout Strip 314 on the winding Strip 312. A Supplemental inulation cover 440 i wrapped about the winding trip 412 and the breakout Strip 414 in the ame manner a decribed above with regard to the Supplemental inulation cover 340. The inulation cover 440 differ from the inulation cover 340 in that the lower, front panel 442 of the inulation cover 440 i abbreviated o that a portion 414E of the breakout Strip 414 remain expoed. For thi reaon, it may be neceary to provide one or more additional inulation layer to provide the Stipulated clearance and ditance through inulation to the next winding. The dimenion E", G", H" and I" correpond to the dimenion E, G, H and I, repectively, of the winding aembly 190. Preferably, each of the ditance E", G", H" and I", a well a the ditance J (the width of the cuff 432A), the ditance K (the width of the cuff 432B), and the ditance L (the width of the panel 442) are equal to or greater than the required or deired creepage ditance and clearance. Optionally, the portion of the winding trip 312, 412 extending leftwardly beyond the breakout trip 314, 414 may be reduced (e.g., to only a few millimeter) and the inulation cover 333, 433 omitted. In thi cae, the Supple mental inulation cover 340, 440 hould extend leftwardly beyond the leftmot edge of the winding trip 312, 412 a ditance correponding to the ditance G (FIG. 1A) di cued above with regard to the winding aembly 190. With reference to FIG. 10, a winding aembly 590 according to a further embodiment of the preent invention i hown therein. The winding aembly 590 include a winding portion 592 and a joined breakout 594. The winding aembly 590 may include a econd breakout on the end of the winding portion 592 oppoite the breakout 594. The contruction of the winding aembly may be better appre ciated from FIGS. 10A to 10D and the decription of a method for forming the winding aembly 590 that follow. US 6,535,100 B A winding trip 512 and a breakout trip 514 are provided and relatively poitioned a hown in FIG. 10B. The brea kout trip 514 i the ame a the breakout trip 314. The winding Strip 512 i the ame a the winding Strip 312 except that a notch 512A i provided adjacent the breakout trip 514. Prior to or following the tep of poitioning the breakout trip 514 on the winding trip 512, an inulation cover 534 correponding to the inulation cover 334 i wrapped about and ecured to the breakout trip 514. Similarly, prior to or following the Step of poitioning the breakout trip 514, an inulation cover 532 correponding to the inulation cover 332 i wrapped about and ecured to the winding trip 512. Notably, it i not neceary to overlap the inulation cover 534 with the winding trip 512. Thereafter, a bellow cover 550 i placed in the inner corner between the breakout trip 514 and the winding trip 512 a hown in FIG. 10D. The bellow cover include oppoed leg portion 554 on either ide of the breakout trip 514 and joined along an edge fold 554A. The bellow cover 550 alo include oppoed leg portion 552 dipoed on either Side of the winding Strip 512 and joined along an edge fold 552A. Oppoed bellow ection 556 join the leg portion 554 and 552 on either ide of the trip 512, 514. The leg portion 552 and 554 overlap the inulation cover 532 and 534, repectively. With reference to FIG. 10A an L-haped cover 560 i applied over the breakout trip 514 and the winding trip 512 a hown. The L-haped cover 560 include oppoed leg portion 564 dipoed on oppoed ide of the breakout Strip 534 and joined along a fold 564A. The L-haped cover 560 alo include oppoed leg portion 562. One or both of the leg portion 562 are folded back to form panel 563 which are joined to the leg portion 562 along a fold 563A. The fold 563A interect the fold 564A to inure that no gap i preented along the rightward and lower edge of the L-haped cover 560. The leg portion 564 overlap the leg portion 554 and a portion of each of the bellow ection 556. The leg portion 552 overlap the inulation cover 534, the leg portion 554, and portion of each of the bellow ection 556. The leg portion 562 overlap the inulation cover 532, the leg portion 552, and portion of each of the bellow Section 556. The bellow cover 550 and the L-haped cover 560 may each be formed of any Suitable inulating material. For example, the bellow cover 550 and the L-haped cover 560 may be formed of the material dicued above with regard to the inulation cover 132 and 134. The foregoing i illutrative of the preent invention and i not to be contrued a limiting thereof. Although a few exemplary embodiment of thi invention have been decribed, thoe killed in the art will readily appreciate that many modification are poible in the exemplary embodi ment without materially departing from the novel teaching and advantage of thi invention. Accordingly, all Such modification are intended to be included within the Scope of thi invention a defined in the claim. Therefore, it i to be undertood that the foregoing i illutrative of the preent invention and i not to be contrued a limited to the Specific embodiment dicloed, and that modification to the di cloed embodiment, a well a other embodiment, are intended to be included within the Scope of the appended claim. The invention i defined by the following claim, with equivalent of the claim to be included therein. That which i claimed i: 1. A method for forming an inulated winding aembly for an electrical tranformer, Said method compriing the Step of

24 13 providing an integral foil Strip having a lengthwie axi, the foil Strip including a winding portion and a breakout portion extending from the winding portion along the lengthwie axi, folding the breakout portion about the winding portion to form a fold between the breakout portion and the winding portion; and thereafter, Securing an inulation cover to the foil Strip. 2. The method of claim 1 wherein Said Step of Securing an inulation cover to the foil Strip include Securing a firt inulation cover to the winding portion and Securing a Second inulation cover to the breakout portion Such that a contact portion of the foil Strip adjacent the fold remain expoed, and further including the Step of Securing a Supple mental inulation cover over the contact portion. 3. The method of claim 2 including overlapping the Second inulation cover over the winding portion by at leat a precribed minimum creepage ditance. 4. The method of claim 2 wherein Said tep of Securing a Supplemental inulation cover over the contact portion include wrapping the Supplemental inulation cover about and between the winding portion and the breakout portion Such that the Supplemental inulation cover include a firt panel covering the breakout portion, a Second panel cover ing a rear Surface of the winding portion, and a third panel dipoed between the winding portion and the breakout portion. 5. The method of claim 4 including: Overlapping the Second inulation cover over the winding portion by at leat a precribed minimum creepage ditance; Overlapping the firt panel of the Supplemental inulation cover over the Second inulation cover by at leat the precribed minimum creepage ditance, and Overlapping the third panel of the Supplemental inulation cover over the winding portion and between the wind ing portion and the breakout portion by at leat the precribed minimum creepage ditance. 6. The method of claim 5 wherein the Supplemental inulation cover ha marginal portion dipoed on oppoed Side of the breakout portion along the lengthwie axi. 7. The method of claim 6 wherein the marginal portion each extend beyond the breakout portion along the length wie axi at leat the precribed minimum creepage ditance. 8. The method of claim 1 wherein the breakout portion i narrower than the winding portion. 9. The method of claim 1 wherein the foil trip ha a widthwie axi perpendicular to the lengthwie axi and further including the Step of folding the breakout portion to form a Second fold and firt and Second Superimpoed breakout portion panel joined along the Second fold, the Second fold extending at an angle relative to the widthwie axi, and wherein the Step of Securing an inulation cover include wrapping the inulation cover about the firt and Second breakout portion panel. 10. The method of claim 9 wherein the foil trip include a connecting portion between the winding portion and the breakout portion, the connecting portion being narrower than each of the winding portion and the breakout portion. 11. The method of claim 10 wherein the winding portion and the breakout portion have Subtantially the ame width. 12. The method of claim 1 wherein aid tep of folding the breakout portion include forming the fold uch that the fold extend at an angle relative to the lengthwie axi. 13. A method for forming an inulated winding aembly for an electrical tranformer, Said method compriing the Step of: US 6,535,100 B2 1O providing a foil winding portion and a foil breakout portion adjoining the winding portion, the breakout portion overlapping and extending at an angle with repect to the winding portion; and wrapping a Supplemental inulation cover about and between the winding portion and the breakout portion Such that the Supplemental inulation cover include a firt panel covering the breakout portion, a Second panel covering a rear Surface of the winding portion, and a third panel dipoed between the winding portion and the breakout portion. 14. The method of claim 13 wherein the winding portion and the breakout portion are formed from a unitary foil Strip. 15. The method of claim 13 wherein the winding portion and the breakout portion are eparately formed foil Strip. 16. A winding aembly for ue in a tranformer, Said winding aembly compriing: a) a foil trip including: a winding portion; and a breakout portion integral with Said winding portion and joined to Said winding portion along a fold; b) a firt inulation cover covering a portion of Said winding portion; c) a econd inulation cover covering a portion of Said breakout portion; and d) a Supplemental inulation cover covering each of Said winding portion and Said breakout portion. 17. The winding aembly of claim 16 wherein aid Supplemental inulation cover cover a contact portion of aid foil trip that i not covered by either of aid firt and Second inulation cover. 18. The winding aembly of claim 16 wherein Said Second inulation cover overlap aid winding portion by at leat a precribed minimum creepage ditance. 19. The winding aembly of claim 16 wherein aid Supplemental inulation cover include a firt panel covering Said breakout portion, a Second panel covering a rear Surface of Said winding portion, and a third panel dipoed between Said winding portion and Said breakout portion. 20. The winding aembly of claim 19 wherein: Said Second inulation cover overlap Said winding por tion by at leat a precribed minimum creepage di tance, Said firt panel of Said Supplemental inulation cover Overlap Said Second inulation cover by at leat Said precribed minimum creepage ditance; and Said third panel of Said Supplemental inulation cover Overlap Said winding portion and between aid wind ing portion and Said breakout portion by at leat Said precribed minimum creepage ditance. 21. The winding aembly of claim 16 wherein aid winding portion ha a lengthwie axi and Said Supplemental inulation cover ha marginal portion dipoed on oppoed Side of Said breakout portion along Said lengthwie axi. 22. The winding aembly of claim 21 wherein aid marginal portion each extend beyond aid breakout portion along Said lengthwie axi at leat Said precribed minimum creepage ditance. 23. The winding aembly claim 16 wherein aid breakout portion i narrower than Said winding portion. 24. The winding aembly of claim 16 wherein: Said breakout include firt and Second Superimpoed breakout portion panel joined along a Second fold; and Said Second inulation cover i wrapped about Said firt and Second breakout portion panel.

25 The winding aembly of claim 16 wherein aid winding portion ha a lengthwie axi and Said fold extend at an angle relative to Said lengthwie axi. 26. A winding aembly for ue in an electrical tranformer, Said winding aembly compriing: a) a foil winding portion; b) a foil breakout portion adjoining aid winding portion, Said breakout portion overlapping and extending at an angle with repect to Said winding portion; and c) a Supplemental inulation cover wrapped about and between aid winding portion and Said breakout portion, Said Supplemental inulation cover including a US 6,535,100 B firt panel covering Said breakout portion, a Second panel covering a rear Surface of Said winding portion, and a third panel dipoed between Said winding por tion and Said breakout portion. 27. The winding aembly of claim 26 wherein aid winding portion and Said breakout portion are formed from a unitary foil Strip. 28. The winding aembly of claim 26 wherein aid winding portion and Said breakout portion are eparately formed foil trip.