WO1999029024A1 - Insulated electrical conductor and contacting method - Google Patents
Insulated electrical conductor and contacting method Download PDFInfo
- Publication number
- WO1999029024A1 WO1999029024A1 PCT/EP1998/007734 EP9807734W WO9929024A1 WO 1999029024 A1 WO1999029024 A1 WO 1999029024A1 EP 9807734 W EP9807734 W EP 9807734W WO 9929024 A1 WO9929024 A1 WO 9929024A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- coating
- layer
- conductor
- conductor according
- semiconductive
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K3/00—Details of windings
- H02K3/32—Windings characterised by the shape, form or construction of the insulation
- H02K3/40—Windings characterised by the shape, form or construction of the insulation for high voltage, e.g. affording protection against corona discharges
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F5/00—Coils
- H01F5/06—Insulation of windings
-
- 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
- H01F27/28—Coils; Windings; Conductive connections
- H01F27/288—Shielding
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G15/00—Cable fittings
- H02G15/02—Cable terminations
- H02G15/06—Cable terminating boxes, frames or other structures
- H02G15/064—Cable terminating boxes, frames or other structures with devices for relieving electrical stress
- H02G15/068—Cable terminating boxes, frames or other structures with devices for relieving electrical stress connected to the cable shield only
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K2203/00—Specific aspects not provided for in the other groups of this subclass relating to the windings
- H02K2203/15—Machines characterised by cable windings, e.g. high-voltage cables, ribbon cables
Definitions
- the present invention relates to an insulated electrical conductor. More specifically, the invention relates to an insulated conductor, for use in high-voltage windings, having an outer layer of (at least semi-) conductive material which is contacted for grounding purposes.
- the conductor is intended to be used in large motors, generators and transformers at voltages in excess of
- the invention relates to a method of establishing electrical contact with
- the conductor 10 comprises strands 12, for example of copper, the majority of which are insulated, surrounded by a first conductive layer 14.
- An insulating layer 16, for example of cross -linked polyethylene (XLPE) surrounds the first conductive layer 14 and is in turn surrounded by a second conductive layer 18.
- XLPE cross -linked polyethylene
- the layers 14, 18 are described as "conductive” they are in practice formed from a base polymer mixed with carbon black or metallic particles and have a volume resistivity of between 1 and 10 s ⁇ -cm, preferably between 10 and 500 ⁇ -cm.
- Suitable base polymers for the layers 14, 18 (and for the insulating layer 16) include ethylene vinyl acetate copolymer/nitrile rubber, butyl grafted polythene, ethylene butyl acrylate copolymer, ethylene ethyl acrylate copolymer, ethylene propene rubber, polyethylenes of low density, poly butylene, poly methyl pentene and ethylene acrylate copolymer.
- the first conductive layer 14 is rigidly connected to the insulating layer 16 over the entire interface therebetween.
- the second conductive layer 18 is rigidly connected to the insulating layer 16 over the entire interface therebetween.
- the layers 14 - 16 form a solid insulation system and are conveniently extruded together around the strands 12.
- the conductivity of the first conductive layer 14 is lower than that of the electrically conductive strands 12, it is still sufficient to equalise the potential over its surface. Accordingly, the electric field is distributed uniformly around the circumference of the insulating layer 16 and the risk of localised field enhancement and partial discharge is minimized.
- the potential at the second conductive layer 18, which should be zero or ground, is equalized at this value by the conductivity of the layer.
- the conductive layer 18 has sufficient resistivity to enclose the electric field. In view of this resistivity, it is desirable to connect the conductive polymeric layer to ground at intervals therealong.
- a problem experienced in making electrical contact with polymeric layers is that they expand in use, due to their high thermal expansion coefficient, and also creep under mechanical loading.
- Paints or glues containing silver particles are sometimes used for contacting microelectronic devices which carry extremely low signal currents.
- an electrical conductor for high voltage windings comprising central conductive means and an outer semiconductive layer, characterised in that a portion of the surface of the conductor is coated with a coating comprising metal particles .
- the central conductive means comprises one or more strands of wire and is surrounded in turn by an inner layer of lower conductivity than the wire, then by an electrically insulating layer and then by the outer layer, which preferably has a higher conductivity than the insulating layer.
- the coating may be a paint or glue, but more preferably, the coating comprises an impact-bonded layer of metal particles. These particles preferably comprise silver particles .
- the coating may directly coat the outer polymeric layer, but advantageously a metallic foil, such as silver foil, is interposed between the coating and the polymeric layer.
- a metallic foil such as silver foil
- the coating (and foil if present) may be applied to a plurality of portions of the polymeric layer at intervals along the conductor.
- At least one grounding wire is connected to the coating.
- a method of establishing electrical contact with a semiconductive polymeric material comprising applying a coating comprising metal particles, preferably comprising silver particles.
- the coating may be painted on, but more preferably the coating is formed by accelerating the metal particles towards the polymeric material, for example in a gas stream.
- the coating is applied directly to the surface of the polymeric material.
- the method comprises the steps of bonding a metal foil to the surface of the polymeric material and applying the coating to the external surface of the metal foil.
- the metal foil could be bonded to the semiconductive polymeric material by ultrasonic welding.
- the method may additionally include connecting at least one grounding wire to the coating.
- the at least one grounding wire may be connected by soldering or by means of a spring-type contacting device.
- the coating is purely metallic for electrical and thermal stability.
- the method of the invention renders localized coating of the semiconductive layer relatively easy, and heating of this layer can be avoided.
- Figure 1 is a transverse section through a conductor according to the invention, but not showing the coating
- Figure 2 is a fragmentary longitudinal section through the conductor of Figure 1, showing the coating being applied according to one embodiment .
- Figure 3 is a section similar to Figure 2, showing the coating being applied according to an alternative embodiment .
- Figure 2 shows how small silver particles 20 are accelerated towards the surface of the conductive polymeric outer layer 18.
- the particles 20 impact the surface of the layer 18, penetrating that layer and contacting the particles of carbon therein. Subsequent particles 20 build up a coating of silver.
- FIG 3 shows an alternative embodiment in which, prior to the impact bonding, silver foil 30 is placed on the surface of the polymeric layer 18 to protect it. Silver particles 20' are then accelerated in a gas stream, impact the silver foil 30 and form a coating thereon. In this embodiment the impact of the particles has a minimized effect on the conductive polymeric layer 18 and electrical contact therewith is improved.
- the silver foil 30 reduces the kinetic energy of the silver particles 20' and prevents them from becoming embedded too deeply.
- the silver foil is ultrasonically welded to the polymeric layer 18.
- grounding wires can be connected thereto.
- a resilient metallic spring member (not shown) may be placed around the coated portion of the conductor for this purpose, and a grounding wire may be soldered to the spring member.
- the spring member may comprise a helical spring in an endless loop arranged around the conductor, or an elongate helical spring urged against several turns of the wound conductor.
- the spring member is preferably of a clad metal, such as a copper alloy clad with silver, gold or platinum.
- the method of the invention is compatible with the extrusion process by which the conductor (which may be a superconductor) is produced.
- the outer conductive polymeric material is not damaged, particularly since mechanical stresses are minimized and chemical reactions avoided.
- electrical conductors according to the invention may comprise windings of power transformers having rated powers from a few hundred kVA up to more than 1000 MVA and with rated voltages from 3 - 4 kV up to very high transmission voltages of from 400 - 800 kV or more.
- partial discharges, or PD constitute a serious problem for known insulation systems. If cavities or pores are present in the insulation, internal corona discharge may arise whereby the insulating material is gradually degraded eventually leading to breakdown of the insulation.
- the electric load on the electrical insulation in use of an electrical conductor according to the present invention is reduced by ensuring that the inner layer of (semi) conductive material of the insulation system is at substantially the same electric potential as conductors of the central electrically conductive means which it surrounds and the (semi) conductive outer layer is at a controlled, e.g. earth, potential.
- the electric field in the electrically insulating layer between these inner and outer layers is distributed substantially uniformly over the thickness of the intermediate layer.
- the electrical conductor can thus be designed to withstand very high operating voltages, typically up to 800 kV or higher.
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Insulated Conductors (AREA)
- Insulation, Fastening Of Motor, Generator Windings (AREA)
- Wire Bonding (AREA)
- Coils Of Transformers For General Uses (AREA)
- Insulating Of Coils (AREA)
Abstract
Description
Claims
Priority Applications (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU21562/99A AU2156299A (en) | 1997-11-28 | 1998-11-30 | Insulated electrical conductor and contacting method |
KR1020007005655A KR20010032415A (en) | 1997-11-28 | 1998-11-30 | Insulated electrical conductor and contacting method |
EP98965720A EP1034608A1 (en) | 1997-11-28 | 1998-11-30 | Insulated electrical conductor and contacting method |
JP2000523748A JP2001525599A (en) | 1997-11-28 | 1998-11-30 | Insulated conductor and contact method |
PL98340719A PL340719A1 (en) | 1997-11-28 | 1998-11-30 | Insulated electric conductor and method of connecting same |
NO20002737A NO20002737D0 (en) | 1997-11-28 | 2000-05-26 | Insulated electrical conductor and contact method |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9725327A GB2331872A (en) | 1997-11-28 | 1997-11-28 | Insulated electrical conductor and contacting method |
GB9725327.2 | 1997-11-28 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1999029024A1 true WO1999029024A1 (en) | 1999-06-10 |
Family
ID=10822874
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/EP1998/007734 WO1999029024A1 (en) | 1997-11-28 | 1998-11-30 | Insulated electrical conductor and contacting method |
Country Status (9)
Country | Link |
---|---|
EP (1) | EP1034608A1 (en) |
JP (1) | JP2001525599A (en) |
KR (1) | KR20010032415A (en) |
AU (1) | AU2156299A (en) |
GB (1) | GB2331872A (en) |
NO (1) | NO20002737D0 (en) |
PL (1) | PL340719A1 (en) |
WO (1) | WO1999029024A1 (en) |
ZA (1) | ZA9810944B (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2015130692A3 (en) * | 2014-02-25 | 2015-11-26 | Essex Group, Inc. | Insulated winding wire containing semi-conductive layers |
US10770945B2 (en) * | 2017-01-06 | 2020-09-08 | Kabushiki Kaisha Toshiba | Rotating electrical machine coil |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2006004847A (en) * | 2004-06-21 | 2006-01-05 | Sankosha Corp | Grounding conductor |
JP2007005174A (en) * | 2005-06-24 | 2007-01-11 | Sumitomo Electric Wintec Inc | Insulation-coated wire, coil and its manufacturing method |
JP5108251B2 (en) * | 2006-04-26 | 2012-12-26 | 住友電気工業株式会社 | Insulated wire and electric coil using the same |
EP3402051A1 (en) * | 2017-05-12 | 2018-11-14 | ABB Schweiz AG | Electric machine with semi-conducting layer on winding for grounding |
EP3402050A1 (en) * | 2017-05-12 | 2018-11-14 | ABB Schweiz AG | Insultated wire of a coil for a random-wound stator |
WO2022249265A1 (en) * | 2021-05-25 | 2022-12-01 | 三菱電機株式会社 | Insulated wire and coil using said insulated wire |
US20230044358A1 (en) * | 2021-08-05 | 2023-02-09 | Essex Furukawa Magnet Wire Usa Llc | Magnet wire with a semi-conductive insulation layer |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3666876A (en) * | 1970-07-17 | 1972-05-30 | Exxon Research Engineering Co | Novel compositions with controlled electrical properties |
US4312793A (en) * | 1978-03-03 | 1982-01-26 | Charneski Mitchell D | Electrical joint compound |
DE4022476A1 (en) * | 1990-07-14 | 1992-01-16 | Thyssen Industrie | Electric cable for three=phase AC winding of linear motor - covers one phase by inner conducting layer surrounded by insulation and outer conducting layer |
-
1997
- 1997-11-28 GB GB9725327A patent/GB2331872A/en not_active Withdrawn
-
1998
- 1998-11-30 KR KR1020007005655A patent/KR20010032415A/en not_active Application Discontinuation
- 1998-11-30 ZA ZA9810944A patent/ZA9810944B/en unknown
- 1998-11-30 EP EP98965720A patent/EP1034608A1/en not_active Withdrawn
- 1998-11-30 WO PCT/EP1998/007734 patent/WO1999029024A1/en not_active Application Discontinuation
- 1998-11-30 PL PL98340719A patent/PL340719A1/en unknown
- 1998-11-30 JP JP2000523748A patent/JP2001525599A/en active Pending
- 1998-11-30 AU AU21562/99A patent/AU2156299A/en not_active Abandoned
-
2000
- 2000-05-26 NO NO20002737A patent/NO20002737D0/en not_active Application Discontinuation
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3666876A (en) * | 1970-07-17 | 1972-05-30 | Exxon Research Engineering Co | Novel compositions with controlled electrical properties |
US4312793A (en) * | 1978-03-03 | 1982-01-26 | Charneski Mitchell D | Electrical joint compound |
DE4022476A1 (en) * | 1990-07-14 | 1992-01-16 | Thyssen Industrie | Electric cable for three=phase AC winding of linear motor - covers one phase by inner conducting layer surrounded by insulation and outer conducting layer |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2015130692A3 (en) * | 2014-02-25 | 2015-11-26 | Essex Group, Inc. | Insulated winding wire containing semi-conductive layers |
US10770945B2 (en) * | 2017-01-06 | 2020-09-08 | Kabushiki Kaisha Toshiba | Rotating electrical machine coil |
Also Published As
Publication number | Publication date |
---|---|
ZA9810944B (en) | 1999-07-15 |
GB2331872A (en) | 1999-06-02 |
GB9725327D0 (en) | 1998-01-28 |
AU2156299A (en) | 1999-06-16 |
NO20002737L (en) | 2000-05-26 |
KR20010032415A (en) | 2001-04-16 |
NO20002737D0 (en) | 2000-05-26 |
GB2331872A9 (en) | |
PL340719A1 (en) | 2001-02-26 |
JP2001525599A (en) | 2001-12-11 |
EP1034608A1 (en) | 2000-09-13 |
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