CA1038051A - Electrostatic shielding of disc windings - Google Patents

Electrostatic shielding of disc windings

Info

Publication number
CA1038051A
CA1038051A CA226,884A CA226884A CA1038051A CA 1038051 A CA1038051 A CA 1038051A CA 226884 A CA226884 A CA 226884A CA 1038051 A CA1038051 A CA 1038051A
Authority
CA
Canada
Prior art keywords
coil
shield
coil section
section
conductor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA226,884A
Other languages
French (fr)
Inventor
Reginald A. Hinton
Kenneth W. Doughty
William N. Kennedy
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co
Original Assignee
General Electric Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by General Electric Co filed Critical General Electric Co
Application granted granted Critical
Publication of CA1038051A publication Critical patent/CA1038051A/en
Expired legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01FMAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00Details of transformers or inductances, in general
    • H01F27/34Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
    • H01F27/343Preventing or reducing surge voltages; oscillations
    • H01F27/345Preventing or reducing surge voltages; oscillations using auxiliary conductors

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Regulation Of General Use Transformers (AREA)
  • Coils Of Transformers For General Uses (AREA)

Abstract

ABSTRACT OF THE DISCLOSURE

An electrostatic shielding arrangement for improving the initial distribution of voltage which in turn reduces the insulation stresses on disc-wound coils resulting from the application of impulses or steep wave-front voltages to such coils. Floating electrostatic shields are placed near or internal of the innermost or the innermost and outermost turns only of a disc coil section. Shields are connected together in pairs, with no more than one shield connection being made between adjacent coil sections.

Description

~3~5~ 5D-3349 Our invention relates to electric inductive apparatus such as transformers, reactors, and the like. The invention is directed to high voltage coils of the disc winding type and particularly to the use of electrostatic shields in such coils for improving the voltage distribution and thereby reducing the insulation stresses created by the application of steep wave front or impulse voltages to these disc winding type coils.
The background of the invention and the invention itself will be described with reference to ~he accompanying drawings, in which:
FIGURE 1 is a graph Oe the initial and Einal impulse voltage distribution ~or a disc wound coil grounded at one end as a function oE the distance along the coll winding.
FIGURE 2 is a diagrammatic sectional view taken on a radial plane of a single strand annular coil illustrating an embodiment of our invention.
FIGURE 3 is a disgrammatic sectional view taken on a radial plane of a multiple strand annular coil illustrating an embodiment of our invention.
FIGURE 4 is a diagrammatic sectional view of a single strand annular coil similar to FIGURE 2 illustrating a modi-fied embodiment of our invention.
FIGURE 5 is a diagrammatic sectional view of a multiple strand annular coil, similar to FIGURE 3, illustrating a modified embodiment of our invention.
It is well known that highly inductive windings such as iron core transformer and reactor windings, when exposed to steep wave Eront or surge voltages, initially exhibit an expotential distribution of voltage drop along the length of the coil winding with a very high voltage gradient at the first few turns adjacent th~ line terminal or high voltage end of ,~ ~

.. ', ~.`.;~
"; .~ ~ ~3 'r, - \

S~

the coil. This non-uniform distribution of surge voltages or potentials is undesirable, as it necessitates thicker insulation between the conductor turns of the coils, and thicker insulation between the first few coil sections ad-jacent the line terminal. Size and cost o electrical inductive apparatus is thus adversely affected. Merely in-creasing the thckness of electrical insulation does not insure that the winding will not ~ail when subjected to surge potentials, as increasing the thickness of the electrical in-sulation reduces the internal or series capacitance of theturns and coiL sections at the line end, which cau9es a still more unfavorable distribution of surge potential. This con-dition arises because the winding pre~ents an imp~dance which is predominantly capacitive to steep wave front voltages. Such capacitive impedance is made up of a complex network of capaci-tances in series and parallel circuit relation. If series capacitance only were present, voltage distribution throughout the windind would be substantially uniform and linear. The initial impulse voltage distribution of a transformer winding grounded at one end is given ~y the relation:

= VO sinh c~ X~
sinh ~c where V = Voltage applied to high potential terminal of coil winding.

X = Percent distance along winding ~rom line end.
I
\l CS
C = Total capacitance between the winding and g ground plane.

and CS = Total series capacitance o the winding.
This initial distribution is shown in Figure 1. It can be seen from this igure that the voltage stress at the impulsed ~ , ., .-` ~ - 2 ~3~ s~l or line end of the coil, as represented by the curved line designated initial impulse voltage distribution, is greater than the steady state voltage distribution given by the straight line designated final distribution. It can be shown that this increase in stress is directly proportional to "C~ ".
It is therefore possible to lower this initial stress by re-ducing " ~ ", which can be accomplished by increasing Cs. It is therefore desirable to construct a winding in such a way that the series capacitance is large relative to the parallel or ground capacitance in the disc/coil winding.
Various electrostatic shielding arrangements have been utilized in the past in an attempt to .increase the series capacitance in order to improve the initial dist~ibution oE an impulse voltage applied to coils o~ the aEorementioned type.
These arrangements have met with varying degrees o success and have resulted in either less than adequate performance or an unavoidable increase in coil size and/or cost. One arrange-ment illustrated in U.S.Patent No. 2,905,911 to I~URITA issued September 22, 1959 involves, in one embodiment thereof, the placing of uninsulated shield conductors between at least the two outermost conductor turns of each disc coil layer or coil section and then the connecting together of these shield con-ductors to form floating shield pairs. While this improves the initial impulse voltage distribution along the outside of the coil winding it does very little to improve the initial voltage distribution along the inside of the coil winding.
Another arrangement illustrated in U.S. Patent No. 3,380,007 to ALVERSON et al issued April 23, 1968, invo]ves in one embodiment thereof, the placement of shield conductors between the two outermost and the two innermost turns of each disc coil layer or coil section. The shields are connected in pairs, alternately aL~ng the inside and the outside of the coil 5D-39~9 ~38/~
windings, to the curren-t carrying conductor at the opposite end of the disc coil section in which said shield is located, said connections to the current carrying conductors causing an undesirable increase in coil si2e and cost.
In order to avoid these and other disadvantages it would be desirable to provide an electrostatic shielding arrangement that would improve the initial distribution of impulse voltage applied to coil windings having serially con-nected disc type coil sections and in addition, reduce both the size and cost of adding such a shielding arrangement to such coils.
Accordingly, it is the principal ob~ect of the present invention to provide an eleatrostatic shlelding arrangement that will improve the initial distribution oE
impulse voltage applied to coil windings having serially connected disc type coil sections.
~ no~her object of the present invention is to provide an electrostatic shielding arrangement for disc type coil wind-ings that will contribute a minimum increase to overall coil size.
A further object of the present invention is to provide an electrostatic shielding arrangement for disc type coil windings that will add a minimum amount of cost to the construction of such coils.
When windings having disc type layers or coil sections are exposed to a steep wave front voltage a disproportionately large amount of said voltage appears across the first few turns oE said coil. This non-uniform distribution o~ voltage necessitates the use of thicker insulation between conductor turns and between the first few coil sections. To cope with this problem, an electrostatic shielding arrangement has been devised capable of produclng a near uniform distribution of ~. , ~q)3~1D5~

impulse voltages when applied to such coils.
In one embodiment floating shields are placed adjacent or internal of the innermost turn only of each coil section. Shields in adjacent coil sections are connected to-gether in pairs near the internal ends of adjacent coil sections having the greatest potential difference between coil conductor turns, when energiz.ing, in adjacent coil sections. The remain-ing shield in the initial disc layer or section at the high voltage end of the winding is connected to the steep wave front voltage source.
In another embodiment floating shields are placed adjacent to or internal of both the innermost and the outer-most turns only of a coil section with only one shield con-nection beiny made ~etween coil sections, alternatel~ at one end and then the other end o~ adjacent coil sections. Shields in adjacent coil sections are connected together in pairs near the ends o~ adjacent coil sections having the greatest poten-tial difference between coil conductor turns, when energized, in adiacent coil sections. A shield in the initial coil sec-tionr at the high voltage end o~ the coil is connected to thesteep waYe-front voltage source.
The invention, which i5 sought to be protected, will ~e particularly pointed out and distinctly claimed in the claims appended thereto. However, it is believed that this invention and the manner in which its o~jects and advantages are o~tained, as well as other objects and advantages thereof, will be more readily understood by re~erence to the ~ollowing detailed descriptions of the preferred embodiments.
Re~erring to the drawings wherein like numerals are used to indicate like parts throughout, in FIGURE 2 a diagram-matic sectional view taken on a radial plane of a ~ .

. ~

~ 5D 3949 5~ .
single strand spirally wound annular disc coil 1~0 incorpor-ating an embodiment of our invention is illustrated. Annular coil 120 is comprised of, from top to bottom, concentrically stacked annular disc layers or coil sections 122, 124, 126 and 128 respectively constructed of insulated conductor turns. Beginning with outermost turn 22, coil section 122 is spirally wound inward to innermost turn 24. An electri-cal connection 26 is made between innermost turn 24 on coil section 122 and innermost turn 28 on adjacent coil section 124. Beginning with turn 28, coil section 124 is spirally wound outward to outermost turn 30. An electrical connec-tion 32 is made ~rom outermost turn 30 o~ coil section 124 to outermost turn 34 o~ coil section 126. Beginning with outermost turn 34, coil section 126 is spirally wound inward, terminating with innermost turn 36. An electrical connection 38 is made from innermost turn 36 of coil section 126 to innermost turn 40 of coil section 128. Beginning with said innermost turn 40, coil section 128 is spirally wound out-ward terminating with outermost turn 42 o~ said coil section 128. Additional coil sections, if necessary, are connected to electrical connection 44 in the same manner as the pre-viously described coil sections. If no further coil sections are to be added, electrical conn~ction 44, or the equivalent, is tied to neutral or ground potential~
A single insulated shield-conductor in the form o~
a thin copper skrip is wound between the kwo innermost kurns o~ each coil section. Shield-conductors 46, 48, 50, and 52 are wound betw~en the two innermost turns o~ coil sections 122, 124, 126 and 128 respectively.
It is well known in the art to place an insulated metallic covered plate, such as static plate 56, adjacent the high potential en~ o~ a disc type coil, such as coil 120.

~ 5D 3949 ~3~
Static plate 56 aids in distributing an impulse voltage applied to disc coil 120 more evenly throughout the high potential end of said coil 120.
Electrical connections are made from shield-conductor 46 and outermost turn 22 of coil section 122 to static plate 56 by elsctrical connections 58 and 60 respectively. Exclud-ing shield-conductor 46 in coil section 122, the remaining adjacent shield conductors are connected together in pairs.
Specifically, shield conductor 48 in coil section 124 is connected to adjacent shield conductor 50 in coil section 126 only, by electrical connection 58. Shield conductor 52 would be connected to a similarly positioned shield in an adjacent coil section (not shown) by electrical connection 62 if another eoil ~ection were utilized. If coil section 128 is the ~inal coil 3~ction or the coil section that is furthest away from the high potential end of coil 120, shield conductor 52 would not be provided in said coil section 128. Ground plane 64 i9 the plane to which voltages in coil 120 are referenced.
Except for shield conductor 46 in coil section 122, the electrostatic shields utilized in coil 120 are arranged along the inside thereof and are alectrically floating. In other words, shield conductoxs 48, 50, and 52 are capacitively coupled only to the current carrying conductor turns of coil 120. There are no electrical connections between said shield conductors 48, 50 and 52 and a non-shield i.e., a coil current carrying conduator.
In coils of the type described herein it is customary design practice, partiaularly in coils required to carry large currents, to con~truct such coils of conductor turns consisting of two or more insulated strands. By utilizing turns having insulate* strands, power loss from local cir-- ` 5D 3949 380~1 culating or eddy currents is greatly reduced The winding arrangement in FIGURE 3 will describe the manner in which electrostatic shislds are placed between strands of a stranded turn, spirally wound, disc section coil and the advantages obtained by such placement.
Re~erence should here be made to FIG~RE 3 which is a diagrammatic sectional view taken on a radial plane of a multiple strand, spirally wound disc section coil incorporat-ing an electrostatic shield in a manner somewhat similar to that illustrated in FIGURE 2. Annular coil 220 is comprised of, ~rom top to bottom, concentrically stacked annu}ar coil sections 222, 224, 226 and 228 respectlvely~ Beginning with the outermost turn of coil section 222, con~i~ting o~ juxta-posed strands la and lb, said coil section 222 i9 wound spirally inward to the innermost turn which consists of juxtaposed strands 5a and 5b. ~djacent coil section 224 is spirally wound outward beginning with the innermost turn consisting of juxtaposed strands 6a and 6b and terminating with juxtapossd strands lOa and lOb of the outermost turn of coil section 224. Strands 5a and 5b of coil section 222 are electrically connected to strands 6a and 6b of coil section 224 by electrical connections 66 and 68 respectively. Coil section 226 adjacent coil section 224 is spirally wound in-ward beginning with juxtaposed strands lla and llb of the outermost turn and terminating with juxtaposed strands 15a and 15b oE the innermost turn. Coil section 228, adjacent coil section 226 is spirally wound outward beginning with juxtaposed strands 16a and 16b of the innermost turn and terminating with juxtaposed strands 20a and 20b of the outer-most turn. Strand lOa and lOb of coil section 224 are con-nected to strands lla and llb of coil section 226 by elec-trical connections 70 and 72 respectively. Strands 15a and 3805~

15b of coil section 226 are electrically connected to strands 16a and 16b of coil section 228 by electrical connections 74 and 76 respecti~ely. Additional coil sections, if anyO are cvnnected to electrical connections 78 and 80 in the same manner as the previously described coil sections. If no further coil sections are to be added, electrical connections 78 and 80, or the e~uivalent thereof, are tied to a neutral point or ground potential. Strands la and lb of coil section 222 are connected to static plate 82 by electrical connec-tions 84 and 86.
~ single insulated shield conductor turn in the form o~ a thin copper strip i8 wound between the strands of or in-ternal of the innermost turn of each coil ~ection. Shield turns 88, gO, 92 and 94 are wound between 3trand~ Sa and 5b, 6a and 6b, lSa and lSb, 16a and 16b, re~pectively. Shield conductor 88 is electrically connected to static plate 82 by electrical connection 96. Shield conductors 90 and 92 are connected together by electrical connection 98. Shield con-nector 94 would be connected to a similarly positioned shield in an adjacent coil section (not shown) by electrical con-nection 100 if another coil section were utilized. If coil section 228 is the final section or the coil section that is furthest away from the high potential end of coil 220, shield conductor turn 94 would not be provided in said coil section 228. Ground plane 102 is the plane to which voltages in coil 220 are referenced.
Except for shield conductor turn 88 in coil section 222, the shields arranged along the inside of coil 220 are electrically floating with respect to the non-shield or the coil current carrying conductor of said coil 220 in the same manner as the shields in the previously described coil ... .... .
120. ~ ~

~ 5D 3949 103~051 With the foregoing shisld arranqement as above described and as illustrated in FIGURES 2 and 3, the initial distribution of an impulse or step voltage applied to coils 120 or 220 is determined primarily by the arrangement of tha aforementioned floating shields along the inside o~ said coils 120 and 220. The increased series capacitance introduced into coils 120 and 220 by these floating shields is much larger than the shunt capacitance of said coils 120 and 220 to ground. Consequently, the initial impulse voltage dis-tribution or the initial impulse voltaye division along the inside of coil~ 120 and 220 is directly proportional to the series capacitance introduced by the a~orementioned ~loating shields; said distribution being almost linear along the con-ductor length o~ said coil~ 120 and 220.
Re~exring here to FIGURE 4 which is a diagrammatic sectional view taken on a radial plane o~ single strand, spirally wound, disc section coil 320 incorporating a modi-fied embodiment of our invention. Annular coil 320 is com-prised of, from top to bottom, concentrically stacked annular disc layers or coil sections 322, 324, 326 and 328 re~pectively.
seginning with outer turn 104, coil section 320 is spirally wound inward to innermost turn 106. Elsctrical connection 108 is made between innermost turn 106 on coil section 322 and innermost turn 110 on adjacent coil section 324. Begin-ning with turn 110, coil section 324 is spirally wound outward to turn 112. Electrical connection 114 is made from outermost turn 112 o~ coil section 324 to outermost turn 116 of coil section 326. Beginning with outermost turn 116, coil section 326 is spirally wound inward, terminating with turn 118.
Electrical connection 122 is made from innermost turn 118 of coil section 326 to innermost turn 124 of coil section 328.
Beginning with said innermost turn 124, coil section 128 is ~ SD 3949 S~
spirally wound outward terminating with outermost turn 126.
Additional coil sections are connected to electrical con- -nection 128 in the same manner as the previously described coil sections. If no further coil sections are to be added, electrical connection 128, or the e~uivalent thereof is con-nected to neutral or ground potential.
A single insulated shield conductor in the form of a thin copper strip is wound between the two innermost turns and the two outermost turns of each coil section. Shield-conductors 130, 132, }34 and 136 are wound between the two innermost turns of coil sections, 322, 324, 326 and 328 respecti~ely. Shield-conductors 138, 140, 142 and 144 are wound between the two outermost turns o~ coil sections 322, 324, 326 and 328 respectively.
Electrical connections are made from outermost turn 104 and shield-conductor 130 of coil section 322 to static plate 146 by electrical connections 148 and 150 respectively.
Excluding shield-conductor 130 in coil section 322, adjacent shield-conductors are connected together in pairs with only one shield connection being made between adjacent coil sec-tions~ Specifically shield-conductor 138 in coil section 322 lS connected to adjacent shield-conductor 140 in coil section 324, only, by electrical connection 152. Shield-conductor 132 in coil section 324 is connected to adjacent shield-conductor 134 in coil section 326 only, by electrical connection 154. Shield-conductor turn 142 in coil section 326 is connected to adjacent shield-conductor 144 in coil section 328 only, by electrical connection 156. Shield-conductor 136 in coil section 328 would be connected to a similarly positioned shield in an adjacent coil section (not shown) by electrical connection 158. If coil section 328 is the final coil section o~ coil 320, shield~conductor 136 would ~ 5D 39~9 ~3~

not be provided in said coil section 328. Except for shield-conductor turn 130 in coil section 322, the shields axranged along the inside and outside of coil 320 are floating or are insulated from the coil current carrying conductor o~ said coil 320~ Ground plane 160 is the plane to which voltages in coil 320 are re~erenced.
Reference should here be made to FIGURE 5 which is a diagrammatic sectional view taken on a radial plane of multiple strand, spirally wound, disc section coil 420 incorporating a modified embodiment of our invention. Annu-lar coi} 420 i9 comprises of, from top to bottom, concen-trically stacked annular coil sections 422, 424, ~26 and 428. Beginning with the outermost turn of coil section 422, consisting o~ juxtaposed strands la and lb, said coil ~eatlon 422 is wound spirally inward to the innermost turn which consists of juxtaposed strands 5a and 5b. Adjacent coil sec-tion 424 is spirally wound outward beginning with the inner-most turn consisting of juxtaposed strands 6a and 6b and terminating with juxtaposed strands lOa and lOb of the outer-most turn of coil section 424. Strands 5a and 5b of coil section 422 ara electrically connected to strands 6a and 6b of coil section 424 by electrical connections 162 and 164 respectively~ Coil section 426 adjacent disc section 424 is spirally wound inward beginning with juxtaposed strands lla and llb of the outermost turn and terminating with juxta-posed strands 15a and 15b o~ the innermost turns. Coil sec-tion 4~8, adjacent coil section 426, is spirally wound ouk-ward beginning with juxtaposed strands 16a and 16b of the innermost turn and terminating with juxtaposed strands 20a and 20b of the outermost turn. Strands lOa and lOb of coil section 424 are connected to strands lla and llb of coil section 426 respectively by electrical connections 166 and 168 respectively. Strands 15~a2a~d 15b of coil section 426 " 5D 3949 ~111313~S~L

are electrically connected to strands 16a and 16b of coil section 428 by electrical connections 170 and 172 respectively.
Additional coil sections, if any, are connected to electrical connections 174 and 176 in the same manner as the previously described coil sections. If no further coil sections are to be added electrical connections 174 and 176, or ~he equiva-lenk thereof, are connected to neutral or ground potential.
Strands la and lb of coil section 422 are connected to static plate 178 by electrical connections 180 and 182.
A single insulated shiled conductor in the form of a thin copper strip is wound between the strands of or internal of the innermost and outermost turns of each coil section.
Shield-conductors 184, 186, 188 and 190 are wound between strands 5a and 5b, 6a and 6b, 15a and 15b and 16a and 16b respectively. Shield-conductors 192, 194, 196 and 198 are wound between strands la and lb, lOa and lOb, lla and llb, and 20a and 20b respectively~ Shield-conductor 184 is electrically connected to static plate 178 by electrical connection 200. Shield conductors 192 and 194 are connected together by electrical connection 202 only. Shield-conductors 186 and 188 are connected together by electrical connection 204 only. Shield conductors 196 and 198 are connected to-gether by eLectrical connection 206 only. Shield-conductor 190 would be connected to a similarly positioned shield in an adjacent coil section (not shown) by electrical connection 208 if another coil section were utiliæed. If coil section 428 is the final disc section, shield-conductor 190 would not be provided in said coil section 428. Ground plane 210 is the reference plane to which voltages in coil 420 are reer-enced, With the foregoing shield arrangement as described in this second embodiment and as illustrated in FIGURES 4 and 5, ~31~05~
the initial distribution of an impulse or o~ a stap function voltage applied to coils 320 and 420 is determined primarily by the arrangement of the aforementioned floating shields along both the inside and outside of said coils 320 and 420.
The aforementioned inner and outer shields in coils 320 and 420 increase the series capacitance to a value significantly greater than the shunt or parallel coil capacitance to ground. Consequently, the initial voltage distribution of an impulse or step function voltage applied to coils 320 and 420 is along the inside and the outside of said coils 320 and 420 and said distribution is directly proportional to the qeries capactiance introduced by the aforementioned inner and outer electrostatic shields; said distribution being almost linear~
As can be seen ~rom the foregoing descriptions, when electrical connections are made between shield-conductors in adjacent coil sections said connection~, when made, are always made between the ends of coil sections having the greatest potential difference.
Although it appears that the inner or both the inner and outer shields must extend the entire axial length of the disc coil, such is not the case. There is an axial point, spaced from the high potential end of a coil, where the increase in coil siza or cost of same outweighs the bene~i-cial ef~ects that additional shields might contribute~ Use o shields beyond this point would be inappropriate.
Table I below gives the calculated initial voltage dis-tribution in terms of " '~ or a typical disc section coil to show the relative effects on the initial impulse voltage distribution of such coils for various electrostatic shielding arrangements. The greater the value of ~ ~C ~ the greater the electrical stress on the insulation at the hi~ potential 1~31~05:~
end of the disc coilO
Table 1 Position of Floatinq Shields ~ c~
None 6.3 Along Outside 5.8 Along Inside 3.2 Along Both 2~6 The quantity "~" is the same " ~ " that has pre-viously been defined for the mathematical relation that expresses the initial impulse voltage distribution of a trans-former winding grounded at one end. The quantity " oC 1' is graphically depictsd in FIGURE 1 alsoO As can be seen Erom Table 1 the initial voltage distribution o~ a disc seation, spirally wound coil employing el~ctrostatic shields along the inside or both the inside and outside is closer to the straight line or final voltage distribution illustrated in FIGURE 1 than coils having no shields or shields along the outside only. The application of shields along both tha inside and the outside gives some additional improvement in the initial voltage distribution over inside shields only. The addition of outside shields essentially adds another voltage divider circuit in parallel with the one on the inside providPd by the internal shields. Both the inside and the outside electrostatic shields reinforce each other and the initial impulse voltage distribution is improved.
Although thin insulated copper strips have been employed to describe the electrostatic shields of the pre-ferred embodiments, such a dhield design is not essential in carrying out our invention~ Design considerations may dictate variations in shield-conductor cross sectional area, material or the use or non-use o~ insulation on said electrostatic shields. Aluminum, for example, can very easily be substituted for copper. These varia,tions and use or non-use of insulation ~3~0531 are not material to the practicing of our invention.
Whether or not a particular coil section is spirally wound inward or outward is determined solely by the direc-tion in which the initial coil section at the high potential end of a coil is wound if such coils are wound from the high potential to the low potential end. In coils 12~, 220, 320 and 420 the initial coil sections are spirally wound inward with the remaining coil sections being wound alternately outward and inward throughout the length of these coils.
Our invention is equally applicable to a coil that has the initial coil section spirally wound outward and then alter-nates the winding direction of the remaining coil sections throughout the length of the coil.
It will be apparent to those skilled in the art from the foregoing description of our invention that various improvements and moaifications can be made in it without departing from the true scope of the invention. Accordingly, it is our intention to encompass within the scope of the appended claims the true limits and spirit of our invention.
. . .
- ~6 :

Claims (13)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. An electrostatic shielding device for inductive apparatus of the type having, a coil, including a plurality of generally coaxially disposed annular disc coil sections, each of said coil sections having a plurality of single strand insulated conductor turns;
spirally wound, in the same direction, alternately radially outward and radially inward, beginning with an initial coil section at one end of said coil and terminating with a final coil section, a finish-end of a coil section being connected to the start-end of an immediately adjacent coil section to form a coil connected in an electrical series circuit relation, the start-end of the initial coil section being for connection to a high potential source and the finish-end of the final coil section being for connection to a low potential point, wherein the improvement comprises:
an electrostatic shield-conductor between the two innermost turns only of coil sections of said coil, the shield-conductor in said initial coil section being for connection to said high potential source, a shield-conductor in one coil sec-tion being electrically connected to a correspondingly positioned shield-conductor in an immediately adjacent coil section only, said shield connections being made between the ends of adjacent coil sections having the greatest potential difference between coil section ends.
2. An electrostatic shield device for inductive appara-tus as defined in claim 1 wherein a static plate is connected in electrical series with said high potential source and said coil, said static plate is located immediately adjacent an outer surface of said initial coil section to more uniformly distribute voltages appearing at a high potential end of said coil.
3. An electrostatic shielding device for inductive apparatus as defined in claim 1 wherein said shield-conductors are formed of thin copper strips of generally rectangular cross-section.
4. An electrostatic shielding device for inductive apparatus of the type having, a coil, including a plurality of generally coaxially disposed annular disc coil sections, each of said coil sections having a plurality of single strand insulated conductor turns;
spirally wound in the same direction alternately radially outward and radially inward, beginning with an initial coil section at one end of said coil and terminating with a final coil section, a finish-end of a coil section being connected to the start-end of an immediately adjacent coil section to form a coil connected in an electrical series circuit relation, the start-end of the initial coil section being for connection to a high potential source and the finish-end of the final coil section being for connection to a low poten-tial point, wherein the improvement comprises:
an electrostatic shield-conductor between the two outermost and the two innermost conductor turns only of coil sections of said coil, a shield conductor at one end of a coil section being connected to the correspondingly positioned shield-conductor only, in an immediately adjacent coil section, with only one shield connection being made between adjacent coil sections, said shield connections being made between the ends of adja-cent coil sections having the greatest potential difference, the remaining shield in said initial coil section being for connection to said high potential source.
5. An electrostatic shielding device for inductive apparatus as defined in claim 4 wherein a static plate is connected in electrical series with said high potential source and said coil, said static plate being located immed-iately adjacent an outer surface of said initial coil section to more uniformly distribute the electrical potential appear-ing at a high potential end of said coil.
6. An electrostatic shielding device for inductive apparatus as defined in claim 4 wherein said shield-conductors are formed of thin copper strips of generally rectangular cross-section.
7. An electrostatic shielding device for inductive apparatus of the type having, a coil including a plurality of generally coaxially disposed annular disc coil sections, each of said coil sections having a plurality of insulated strands;
spirally wound, in the same direction, alternately radially outward and radially inward, beginning with an initial coil section at one end of said coil and terminating with a final coil section, a finish-end of a coil section being con-nected to the start-end of an immediately adjacent coil section to form a coil connected in an electrical series circuit re-lation, the start-end of the initial coil section being for con-nection to a high potential source and the finish-end of the final coil section being for connection to a low potential point;
wherein the improvement comprises:

an electrostatic shield-conductor between said insulated strands of the innermost turn only, of coil sections of said coil, the shield-conductor in said initial coil section being for connection to said high potential source, a shield-conductor in one coil section being electrically connected to a correspondingly positioned shield-conductor in an immediately adjacent coil section only, said shield connections being made between the ends of adjacent coil sections having the greatest potential difference between coil section ends.
8. An electrostatic shielding device for inductive apparatus as defined in claim 7 wherein a static plate is connected in electrical series with said high potential source and said coil, said static plate being located immediately ad-jacent an outer surface of said initial coil section to more uniformly distribute a transient electrical voltage appearing at a high potential end of said coil.
9. An electrostatic shielding device for inductive apparatus as defined in claim 7 wherein said shield-conductors are formed of thin copper strips of generally rectangular cross-section.
10. An electrostatic shielding device for inductive apparatus of the type having, a coil, including a plurality of generally coaxially disposed annular disc coil sections, each of said coil sections having a plurality of conductor turns, each turn including a plurality of insulated strands;
spirally wound, in the same direction, alternately radially outward and radially inward, beginning with an initial coil section at one end of said coil, and terminating with a final coil section, a finish-end of a coil section being con-nected to the start-end of an immediately adjacent coil section to form a coil connected in an electrical series circuit re-lation, the start-end of the initial coil section being for connection to a high potential source and the finish-end of the final coil section being for connection to a low potential point, wherein the improvement comprises:
an electrostatic shield-conductor between said insulated strands of the two outermost and the two innermost turns only of coil sections of said coil, a shield-conductor at one end of a coil section being connected to the correspond-ingly positioned shield conductor only in an immediately ad-jacent coil section, with only one shield connection being made between adjacent coil sections, said shield connections being made between the ends of adjacent coil sections having the greatest potential dif-ference, the remaining shield in said initial coil section being for connection to said high potential source.
11. An electrostatic shield device for inductive apparatus as defined in claim 10 wherein a static plate is con-nected in electrical series with said high potential source and said coil, said static plate being located immediately adjacent an outer surface of said initial coil section to more uniformly distribute voltage surges appearing as a high potential end of said coil.
12. An electrostatic shielding device for inductive apparatus as defined in claim 10 wherein said shield-conductors are formed of thin copper strips of generally rectangular cross-section.
13.An electrostatic shielding device for inductive apparatus of the type having, a coil, including a plurality of generally coaxially disposed annular disc coil sections, each of said coil sections having a plurality of insulated conductor turns;

(Claim 13 contd) spirally wound, in the same direction, alternately radially outward and radially inward beginning with an initial coil section at one end of said coil and terminating with a final coil section, a finish-end of a coil section being con-nected to the start-end of an immediately adjacent coil section to form a coil connected in an electrical series circuit re-lation, the start-end of the initial coil section being for connection to a high potential source and the finish-end of the final coil section being for connection to s low potential point, wherein the improvement comprises:
an electrostatic shield-conductor between an inner-most portion of an innermost turn and the immediately adjacent turn only of a coil section, the shield-conductor in said initial coil section being for connection to said high potential source, a shield-conductor in one coil section being electrically connected to a correspondingly positioned shield-conductor in an immediately adjacent coil section only, said shield connections being made between the ends of adjacent coil sections having the greatest potential difference.
CA226,884A 1974-06-03 1975-05-14 Electrostatic shielding of disc windings Expired CA1038051A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US47552274A 1974-06-03 1974-06-03

Publications (1)

Publication Number Publication Date
CA1038051A true CA1038051A (en) 1978-09-05

Family

ID=23887935

Family Applications (1)

Application Number Title Priority Date Filing Date
CA226,884A Expired CA1038051A (en) 1974-06-03 1975-05-14 Electrostatic shielding of disc windings

Country Status (6)

Country Link
CA (1) CA1038051A (en)
CH (1) CH587549A5 (en)
DE (1) DE2523054A1 (en)
ES (1) ES438117A1 (en)
FR (1) FR2275863A1 (en)
GB (1) GB1514963A (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2034888B1 (en) * 1991-07-11 1994-02-16 Madaus Cerafarm Lab PROCEDURE FOR OBTAINING THE TOTAL ACID FRACTION OF THE LIPID EXTRACTS OF THE FRUITS OF THE SABAL SERRULATA.
CN115440478A (en) * 2022-09-26 2022-12-06 广州西门子变压器有限公司 Composite wires for power transformer windings and power transformers

Also Published As

Publication number Publication date
DE2523054A1 (en) 1975-12-18
GB1514963A (en) 1978-06-21
FR2275863A1 (en) 1976-01-16
CH587549A5 (en) 1977-05-13
FR2275863B1 (en) 1981-12-24
ES438117A1 (en) 1977-01-16

Similar Documents

Publication Publication Date Title
US5012125A (en) Shielded electrical wire construction, and transformer utilizing the same for reduction of capacitive coupling
US7046492B2 (en) Power transformer/inductor
EP0071435B1 (en) Electric cable and electric cable installations
JP2001525607A (en) Transformer
GB1594550A (en) Winding and insulating system for high voltage electrical machine
CA1104671A (en) Transient voltage distribution improving line shield for layer wound power transformer
JP2001518698A (en) How to fit power transformers / reactors with high voltage cables
US4042900A (en) Electrostatic shielding of disc windings
CA1038051A (en) Electrostatic shielding of disc windings
JPH05325658A (en) Electromagnetic shielding cable
US4318066A (en) Externally shielded disk windings for transformers
CA1078476A (en) Impulse voltage distribution improving partial-turn electrostatic shields for disc windings
JPH02132809A (en) Multiplex cylindrical winding
US3466584A (en) Winding for a stationary induction electrical apparatus
EP0190930A2 (en) Transient voltage protection for toroidal transformer
US3387243A (en) Inductive disk winding with improved impulse voltage gradient
US3983522A (en) Tapering electrostatic shields for disc windings
US3631367A (en) Conical layer type radial disk winding with interwound electrostatic shield
EP1060487B1 (en) High frequency snubber for transformers
EP1060483B1 (en) Winding transient suppression technique
CA1212435A (en) Electrical transformer having corona shielding means
JP3522290B2 (en) Disk winding
US1962379A (en) Electrical apparatus
Niasar et al. Impulse Voltage distribution on transformer winding
US3030551A (en) Electrical apparatus