US3546358A - Shielded electrical inductive apparatus - Google Patents

Shielded electrical inductive apparatus Download PDF

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Publication number
US3546358A
US3546358A US715620A US3546358DA US3546358A US 3546358 A US3546358 A US 3546358A US 715620 A US715620 A US 715620A US 3546358D A US3546358D A US 3546358DA US 3546358 A US3546358 A US 3546358A
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United States
Prior art keywords
wire
woven
sheet
losses
flux
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Expired - Lifetime
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US715620A
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English (en)
Inventor
Dieter Pohl
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Siemens AG
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Siemens AG
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields
    • H05K9/0073—Shielding materials
    • H05K9/0075—Magnetic shielding materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/06—Fibrous reinforcements only
    • B29C70/08—Fibrous reinforcements only comprising combinations of different forms of fibrous reinforcements incorporated in matrix material, forming one or more layers, and with or without non-reinforced layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/88—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts characterised primarily by possessing specific properties, e.g. electrically conductive or locally reinforced
    • B29C70/882—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts characterised primarily by possessing specific properties, e.g. electrically conductive or locally reinforced partly or totally electrically conductive, e.g. for EMI shielding
    • B29C70/885—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts characterised primarily by possessing specific properties, e.g. electrically conductive or locally reinforced partly or totally electrically conductive, e.g. for EMI shielding with incorporated metallic wires, nets, films or plates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/34—Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
    • H01F27/36—Electric or magnetic shields or screens
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/34—Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
    • H01F27/36—Electric or magnetic shields or screens
    • H01F27/361—Electric or magnetic shields or screens made of combinations of electrically conductive material and ferromagnetic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/34—Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
    • H01F27/36—Electric or magnetic shields or screens
    • H01F27/363—Electric or magnetic shields or screens made of electrically conductive material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/34—Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
    • H01F27/36—Electric or magnetic shields or screens
    • H01F27/366—Electric or magnetic shields or screens made of ferromagnetic material
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K3/00—Details of windings
    • H02K3/42—Means for preventing or reducing eddy-current losses in the winding heads, e.g. by shielding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/0058—Liquid or visquous
    • B29K2105/0067—Melt
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/25—Solid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/25—Solid
    • B29K2105/251—Particles, powder or granules
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/25—Solid
    • B29K2105/253—Preform
    • B29K2105/256—Sheets, plates, blanks or films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
    • B29K2995/0003—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds having particular electrical or magnetic properties, e.g. piezoelectric
    • B29K2995/0005—Conductive

Definitions

  • Lackey ABSTRACT Electrical inductive apparatus having a flux producing component disposed within a casing formed of a metallic, magnetic material, and shielding means disposed [54] igi i f g g INDUCTWE between the flux producing component and the casing.
  • the 6 cm 11 D h m shielding means is formed of at least one layer of a woven 8 fabric, with the fabric strands which run parallel with one [52] [1.8. CI. 174/35, another in a first direction being formed of metallic wire.
  • the invention relates in general to means for shielding stray magnetic fields associated with electrical inductive apparatus such as transformers and rotating electrical machines.
  • woven wire fabric it is possible to employ woven iron in which at least one direction of the wire fibers is electrically insulated, or a fabric can be used in which the fibers in one direction consist of an insulating material, while the other consists of iron.
  • the characteristic form of the weave ensures good and uniform electrical insulation of the iron wires.
  • the insulating fibers can be made of plastics, such as nylon, for example. Exceptionally good space-filling can be obtained when the iron wires are packed together as closely as possible. This situation can be obtained if, for example, the thickness of the insulating fibers is appreciably smaller than that of the iron wires. Good space utilization also signifies that the total space employed by the screening device is filled to the greatest possible extent with magnetically effective iron. The better the space-usage, the less space is occupied by the screening device. This can be of very great significance when it is required to produce the most compact form of electrical machines.
  • Iron wire-synthetic fiber woven fabrics such as those already employed for other purposes, will serve to produce compound-packaging of several layers of parallel wires.
  • the warp may consist of iron wire and the woof, for example, of nylon threads, or the reverse.
  • the fabric faces can easily be finished in many ways and joined together with resins to form multilayer sheets. This compound sheet material should display great improvements in fatigue strength by com- III parison with glued (cemented) sheets because there are no outstanding planes of preferred strength and an altogether more uniform material is produced.
  • FIG. 1 provides a schematic representation of a magnetically permeable shield into which penetrates a stray flux (stray magnetic field);
  • FIGS. 2a and b show schematically the magnetic flux and the eddy-current flow pattern in a round iron wire
  • FIGS. 30 and b show schematically the transverse magnetic circulation in parallel iron wires
  • FIG. 4 provides a schematic representation of a commercially available woven wire fabric
  • FIGS. 5a and b show schematically woven iron fabrics having improved space-filling in accordance with the invention
  • FIG. 6 shows in graphicalform the ratio of the eddy-current losses in wire to the the losses in sheet material or to the losses in sheet material subdivided into strips during longitudinal magnetic circulation as a function of the wire diameter of a woven wire fabric plate;
  • FIG. 7 shows in graphical form the ratio of the eddy-current losses in wire to the losses in sheet material, or to the losses in sheet material subdivided into strips, during transverse magnetic circulation, as a function of the wire diameter of a woven wire fabric plate;
  • FIG. 8 is a plan view of electrical inductive apparatus, shielded according to the teachings of the invention.
  • FIG. 1 there is shown a schematic representation of the general case of a prior art magnetically permeable shielding plate into which is passing a stray flux (side view).
  • the flux forced into the shielding plate is transmitted longitudinally and then emerges again.
  • Shielding plate 11 is subdivided into several layers 12.
  • the path taken by the stray flux I is shown by the arrows 13.
  • the regions of transverse magnetic circulation (flow) are denoted by 14, while-15 denotes those regions in the shielding plate where the magnetic circulation is longitudinal.
  • FIGS. 20 and 2b show in a schematic manner the paths taken by the magnetic flux and the eddy-current in an iron wire of circular cross section.
  • the magnetic flux 21 in the longitudinal direction of an iron wire 23 is indicated by the arrow 22.
  • the circular-shaped eddy-current produced around the longitudinal axis of the iron wire by the magnetic flux are denoted by 24.
  • FIGS. 3a and 3b The transverse magnetic circulation in parallel iron wires in different relative positions is shown schematically in FIGS. 3a and 3b.
  • the wires are denoted by 31 and the lines of magnetic flux by 32. I
  • FIG. 4 shows in cross section a schematic representation of a commercially available woven wire fabric with insulating fibers.
  • the iron wires are denoted by 41 and the insulating fibers by 42.
  • FIGS. 5a and 5b show woven wire fabrics which, in accordance with the invention, are suitable for improving the use of space on account of their design.
  • FIG. 5a shows a woven wire fabric with a ratio of wire thickness of wire 51 to fiber thickness of insulating fiber 52 of 4:1.
  • FIG. 5b shows that wires 53 can be satisfactorily aligned by weaving in the form of flat wire and held in place, the said wires being converted to the finest of strips by rolling, such a degree of fineness being unobtainable by the slitting of sheet material.
  • Such flat wires, made from thicker material can produce the same reduction in the longitudinal losses as correspondingly thinner wire of circular section, whereby the otherwise most greatly weakened and vanishingly small transverse losses are increased somewhat.
  • An additional advantage is that of a higher space-filling. This is because of flat wire,
  • the insulating fibers are identified by the number 54.
  • the woof must consist of very fine insulating threads each consisting of several fibers, if necessary, to retain their strength, instead of the woof consisting, in customary fashion, of a single or two-ply fiber which corresponds closely in thickness to that of the wire.
  • the insulating fibers consisting of, for example, thermoplastic synthetic fibers
  • the layers can thus be baked together.
  • the combining of the strips of woven material to form a composite sheet can be effected in the usual manner as in the production of conventional plied materials such as, for example, resin bonded fabrics, This can be further extended or improved by the interposition of layers of thermoplastic films or thermoplastic fabrics or thermoplastic flakes or thermoplastic mats or by the scattering of thermo or Duroplastic powder or thermo or Duroplastic shavings on the surfaces and finally pressing with the application of heat, or by the use of glues or other bonding materials, such as, for example, by soaking with a casting resin.
  • the strips of woven fabric are placed on top of each other with the nap running in the same direction and then bonded into a multiply sheet, one obtains two preferred magnetic directions for a material incorporating iron wire in both the warp and the woof, whereas, only one preferred direction of magnetization is obtained in the wire-direction for a material having an iron wire warp and an insulating fiber woof.
  • a preferred direction can be provided for cases where the stray flux is in a known, constant direction.
  • the best magnetic use is made of the iron cross section in the shielding device.
  • the preferred magnetic directions do not have to be rectilinear. Rather, they can follow the most advantageous curved paths consistent with the prevailing conditions becauseespecially prior to the bonding the multilayered composite-the woven wire fabric can just as easily be warped in the plane of the sheet as bent at right-angles to it,
  • FIG. 6 gives a graphical representation of the ratio of the eddy-current losses P,, in the wire to the losses P, which occur either in sheet material or sheet material which has been subdivided into strips, the ratio being for longitudinal magnetic flux and drawn as a function of the wire-diameter D of a wire in a woven wire fabric plate.
  • the wire-diameter D in mm. is plotted as abscissa and the ratio P, /P,, as ordinate.
  • the numerals associated witheach line in the graphs refer to the parameter, that is, to the thickness in mm. of the sheet material or to the strips ofsheet material.
  • the longitudinal losses are reduced by about l percent, for example, by employing woven wire fabric with a wire diameter of 0.5 mmv by comparison with sheet material having a thickness of5 mm. With the same thickness of wire and sheet, the losses are reduced by about 40 percent.
  • FIG. 7 provides a graphical representation ofthe ratio of the eddy-current losses P,, in the wire to the losses P in sheet or in sheet subdivided into strips, the ratio being for transverse magnetic flux and shown as a function of the diameter D of a wire in a woven wire plate.
  • the wire diameter is taken in mm. as the abscissa while the ordinate is plotted with the ratio P /P
  • the reference numbers on the curves again refer to the parameter which in this case can be the breadth in cm. of the sheet material or of the strips.
  • FIG. 8 is a plan view of electrical inductive apparatus with its cover removed, such as a transformer or reactor, illustrating how the teachings of the invention may be applied.
  • Electrical inductive apparatus 80 includes a flux producing component 82, which in this instance is illustrated as being a core-winding assembly of a polyphase transformer or reactor ofthe core-form type, having electrical winding assemblies 84, 86, and 88 disposed in inductive relation with a magnetic core 90.
  • the core-winding assembly 82 is disposed within a tank or casing 92 which is formed of a metallic, magnetic material, such as steel.
  • shielding means 94, 96, 98 and 100 are disposed between the core-winding assembly 82 and the sidewalls of the casing 92. Similar shielding means may be disposed to shield the bottom and cover of the casing, if necessary.
  • Shielding means 94, 96, 98'and 100 are formed according to the teachings of the invention, each having one or more layers of plies of a woven fabric, in which metallic wire is used to form the strands which run parallel with one another in a first direction.
  • the strands which are woven with the strands of the first direction are either formed of an electrical insulating material, or of metallic wires which are electricallyinsulated from the metallic wires of the first direction.
  • the shielding means may be secured in the desired location relative to the inside of the casing by suitable anchors 102 which are secured to the casing and project outwardly therefrom to engage suitable openings in the shielding means.
  • the shielding means may be a plurality of sheets, as illustrated, or one continuous sheet may be used, depending upon the size of the apparatus to be shielded, and the economically practical maximum dimensions of the sheetlike shielding means.
  • apparatus 80 shown in FIG. 8 is illustrated as being a polyphase transformer or reactor of the core-form type, it is to be understood that the teachings of the invention may be beneficially applied to single-phase transformers and reactors of the core and shellform types, and to polyphase transformers and reactors of the shell-form type, as well as generally to any encased flux producing component whose casing is to be shielded from stray magnetic flux.
  • magnetic wires such as iron or steel
  • nonmagnetic metallic wires such as aluminum or copper
  • shield the casing by setting up a counter flux which opposes the flux from the flux producing component, and, therefore, reduces the total amount of flux reaching'the casing.
  • a combination of magnetic and nonmagnetic metallic wires may be used.
  • Electrical inductive apparatus comprising:
  • said shielding means consisting of a plurality of layers of a woven fabric, said woven fabric having a plurality of metallic strands running in a first direction, woven with a plurality of thermoplastic insulating strands running in a second direction, the material of said thermoplastic insulating strands bonding the plurality of layers of woven fabric together.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Composite Materials (AREA)
  • Mechanical Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
  • Laminated Bodies (AREA)
US715620A 1967-04-07 1968-03-25 Shielded electrical inductive apparatus Expired - Lifetime US3546358A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DES0109230 1967-04-07

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JP (1) JPS4522644B1 (de)
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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3808489A (en) * 1972-09-01 1974-04-30 Gen Electric Cooled flux shield for generator terminal box
US3827018A (en) * 1973-11-02 1974-07-30 Westinghouse Electric Corp Power transformer having flux shields surrounding metallic structural members
US4231074A (en) * 1978-09-18 1980-10-28 General Electric Company Zero sequence current source for transformer having a nonwound tertiary
US4451812A (en) * 1979-06-19 1984-05-29 Sphere Investments Limited Electrostatic shield
US4458099A (en) * 1981-03-19 1984-07-03 Hitachi, Ltd. Three-phase combined type gas insulated electrical apparatus
US4977301A (en) * 1988-10-13 1990-12-11 Matsushita Electric Industrial Co., Ltd. High-frequency heating apparatus using frequency-converter-type power supply
US20080173464A1 (en) * 2007-01-18 2008-07-24 Rajendran Nair Shielded flat pair cable with integrated resonant filter compensation
WO2019158429A1 (de) * 2018-02-13 2019-08-22 Siemens Aktiengesellschaft Spaltrohr für eine elektrische maschine aus einem faserverbundwerkstoff, elektrische maschine sowie herstellungsverfahren
NO20211255A1 (en) * 2021-10-19 2023-04-20 Alva Ind As Woven electromagnetic mat and method for connection of ends thereof

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3808489A (en) * 1972-09-01 1974-04-30 Gen Electric Cooled flux shield for generator terminal box
US3827018A (en) * 1973-11-02 1974-07-30 Westinghouse Electric Corp Power transformer having flux shields surrounding metallic structural members
US4231074A (en) * 1978-09-18 1980-10-28 General Electric Company Zero sequence current source for transformer having a nonwound tertiary
US4451812A (en) * 1979-06-19 1984-05-29 Sphere Investments Limited Electrostatic shield
US4458099A (en) * 1981-03-19 1984-07-03 Hitachi, Ltd. Three-phase combined type gas insulated electrical apparatus
US4977301A (en) * 1988-10-13 1990-12-11 Matsushita Electric Industrial Co., Ltd. High-frequency heating apparatus using frequency-converter-type power supply
US20080173464A1 (en) * 2007-01-18 2008-07-24 Rajendran Nair Shielded flat pair cable with integrated resonant filter compensation
WO2019158429A1 (de) * 2018-02-13 2019-08-22 Siemens Aktiengesellschaft Spaltrohr für eine elektrische maschine aus einem faserverbundwerkstoff, elektrische maschine sowie herstellungsverfahren
NO20211255A1 (en) * 2021-10-19 2023-04-20 Alva Ind As Woven electromagnetic mat and method for connection of ends thereof
NO347856B1 (en) * 2021-10-19 2024-04-22 Alva Ind As Woven electromagnetic mat and method for connection of ends thereof

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Publication number Publication date
DE1638564A1 (de) 1970-11-05
JPS4522644B1 (de) 1970-07-30

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