Insulated transformer foil windings with breakouts and methods for forming the same

• US 6,535,100 B2
• Filed: 12/29/2000
• Issued: 03/18/2003
• Est. Priority Date: 04/14/2000
• Status: Expired due to Fees

• Current Assignee: Powerware Corporation (Eaton Corporation PLC.)
• Original Assignee: Powerware Corporation (Eaton Corporation PLC.)
• Inventors: Forss, Börje Anders
• Primary Examiner(s): MAI, ANH T
• Application Number:
  US09/751,035
• Publication Number:
  US 20020057177A1
• Time in Patent Office: 809 Days
• Field of Search: 336/223, 336/200, 336/225, 336/232, 296/021, 296/05, 296/07
• US Class Current: 336/225
• CPC Class Codes: H01F 27/323 Insulation between winding turns, between winding layers
• CPC Class Codes: H01F 41/0213 Manufacturing of magnetic circuits made from strip(s) or ribbon(s) magnetic cores made by winding a ribbon H01F27/25
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor

Abstract

Winding assemblies for use in transformers include one or more foil strips and insulation covers arranged to provide electrically insulated winding and breakout portions. The winding assemblies may be constructed so as to meet creepage distance and other requirements in a margin free coil design transformer.

Claims

1. A method for forming an insulated winding assembly for an electrical transformer, said method comprising the steps of:

providing an integral foil strip having a lengthwise axis, the foil strip including a winding portion and a breakout portion extending from the winding portion along the lengthwise axis;

folding the breakout portion about the winding portion to form a fold between the breakout portion and the winding portion; and

thereafter, securing an insulation cover to the foil strip.

2. The method of claim 1 wherein said step of securing an insulation cover to the foil strip includes securing a first insulation cover to the winding portion and securing a second insulation cover to the breakout portion such that a contact portion of the foil strip adjacent the fold remains exposed, and further including the step of securing a supplemental insulation cover over the contact portion.

3. The method of claim 2 including overlapping the second insulation cover over the winding portion by at least a prescribed minimum creepage distance.

4. The method of claim 2 wherein said step of securing a supplemental insulation cover over the contact portion includes wrapping the supplemental insulation cover about and between the winding portion and the breakout portion such that the supplemental insulation cover includes a first panel covering the breakout portion, a second panel covering a rear surface of the winding portion, and a third panel disposed between the winding portion and the breakout portion.

5. The method of claim 4 including:

overlapping the second insulation cover over the winding portion by at least a prescribed minimum creepage distance;

overlapping the first panel of the supplemental insulation cover over the second insulation cover by at least the prescribed minimum creepage distance; and

overlapping the third panel of the supplemental insulation cover over the winding portion and between the winding portion and the breakout portion by at least the prescribed minimum creepage distance.

6. The method of claim 5 wherein the supplemental insulation cover has marginal portions disposed on opposed sides of the breakout portion along the lengthwise axis.

7. The method of claim 6 wherein the marginal portions each extend beyond the breakout portion along the lengthwise axis at least the prescribed minimum creepage distance.

8. The method of claim 1 wherein the breakout portion is narrower than the winding portion.

9. The method of claim 1 wherein the foil strip has a widthwise axis perpendicular to the lengthwise axis and further including the step of folding the breakout portion to form a second fold and first and second superimposed breakout portion panels joined along the second fold, the second fold extending at an angle relative to the widthwise axis, and wherein the step of securing an insulation cover includes wrapping the insulation cover about the first and second breakout portion panels.

10. The method of claim 9 wherein the foil strip includes 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 substantially the same width.

12. The method of claim 1 wherein said step of folding the breakout portion includes forming the fold such that the fold extends at an angle relative to the lengthwise axis.

13. A method for forming an insulated winding assembly for an electrical transformer, said method comprising the steps of:

providing a foil winding portion and a foil breakout portion adjoining the winding portion, the breakout portion overlapping and extending at an angle with respect to the winding portion; and

wrapping a supplemental insulation cover about and between the winding portion and the breakout portion such that the supplemental insulation cover includes a first panel covering the breakout portion, a second panel covering a rear surface of the winding portion, and a third panel disposed 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 separately formed foil strips.

16. A winding assembly for use in a transformer, said winding assembly comprising:

a) a foil strip including;

a winding portion; and

a breakout portion integral with said winding portion and joined to said winding portion along a fold;

b) a first insulation cover covering a portion of said winding portion;

c) a second insulation cover covering a portion of said breakout portion; and

d) a supplemental insulation cover covering each of said winding portion and said breakout portion.

17. The winding assembly of claim 16 wherein said supplemental insulation cover covers a contact portion of said foil strip that is not covered by either of said first and second insulation covers.

18. The winding assembly of claim 16 wherein said second insulation cover overlaps said winding portion by at least a prescribed minimum creepage distance.

19. The winding assembly of claim 16 wherein said supplemental insulation cover includes a first panel covering said breakout portion, a second panel covering a rear surface of said winding portion, and a third panel disposed between said winding portion and said breakout portion.

20. The winding assembly of claim 19 wherein:

said second insulation cover overlaps said winding portion by at least a prescribed minimum creepage distance;

said first panel of said supplemental insulation cover overlaps said second insulation cover by at least said prescribed minimum creepage distance; and

said third panel of said supplemental insulation cover overlaps said winding portion and between said winding portion and said breakout portion by at least said prescribed minimum creepage distance.

21. The winding assembly of claim 16 wherein said winding portion has a lengthwise axis and said supplemental insulation cover has marginal portions disposed on opposed sides of said breakout portion along said lengthwise axis.

22. The winding assembly of claim 21 wherein said marginal portions each extend beyond said breakout portion along said lengthwise axis at least said prescribed minimum creepage distance.

23. The winding assembly claim 16 wherein said breakout portion is narrower than said winding portion.

24. The winding assembly of claim 16 wherein:

said breakout includes first and second superimposed breakout portion panels joined along a second fold; and

said second insulation cover is wrapped about said first and second breakout portion panels.

25. The winding assembly of claim 16 wherein said winding portion has a lengthwise axis and said fold extends at an angle relative to said lengthwise axis.

26. A winding assembly for use in an electrical transformer, said winding assembly comprising:

a) a foil winding portion;

b) a foil breakout portion adjoining said winding portion, said breakout portion overlapping and extending at an angle with respect to said winding portion; and

c) a supplemental insulation cover wrapped about and between said winding portion and said breakout portion, said supplemental insulation cover including a first panel covering said breakout portion, a second panel covering a rear surface of said winding portion, and a third panel disposed between said winding portion and said breakout portion.

27. The winding assembly of claim 26 wherein said winding portion and said breakout portion are formed from a unitary foil strip.

28. The winding assembly of claim 26 wherein said winding portion and said breakout portion are separately formed foil strips.