WO2025201784A1 - Bushing, electrical apparatus and method - Google Patents

Bushing, electrical apparatus and method

Info

Publication number
WO2025201784A1
WO2025201784A1 PCT/EP2025/055182 EP2025055182W WO2025201784A1 WO 2025201784 A1 WO2025201784 A1 WO 2025201784A1 EP 2025055182 W EP2025055182 W EP 2025055182W WO 2025201784 A1 WO2025201784 A1 WO 2025201784A1
Authority
WO
WIPO (PCT)
Prior art keywords
main part
bushing
cover
elastomeric material
self
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.)
Pending
Application number
PCT/EP2025/055182
Other languages
French (fr)
Inventor
Jan Czyzewski
Robert Platek
Cenk Kurtulus
Orhan Akbas
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.)
Hitachi Energy Ltd
Original Assignee
Hitachi Energy Ltd
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 Hitachi Energy Ltd filed Critical Hitachi Energy Ltd
Publication of WO2025201784A1 publication Critical patent/WO2025201784A1/en
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B17/00—Insulators or insulating bodies characterised by their form
    • H01B17/26—Lead-in insulators; Lead-through insulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B17/00—Insulators or insulating bodies characterised by their form
    • H01B17/32—Single insulators consisting of two or more dissimilar insulating bodies
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B19/00—Apparatus or processes specially adapted for manufacturing insulators or insulating bodies
    • H01B19/04—Treating the surfaces, e.g. applying coatings

Definitions

  • the present disclosure relates to a bushing and a l iquid insulated electrical apparatus comprising the bushi ng.
  • the electrical apparatus may be a transformer or a swit chgear, for example.
  • the present disclosure further relates to a method for manufacturing a bushing, in particular a method formanufacturing the bushing described herein.
  • a bushing for example, enables a conductor to pass through a wall of an electrical apparatus, providing electric al insulation between the conductorand the wall.
  • GB 1281583 A relates to a polymeric electric insu lator sleeve,which comprisessintered particlesof polytetrafluoroethylene, or neoprene, butyl or sili cone rubber. Itisdesirable to provide a bushing thatprovides a reliable operation. It is further desirable to provide a met hod for manufacturing a bushing that is reliable and cost-e ffective.
  • Embodimentsofthe disclosure relate to a bushing. In particular,the bushing isconfigured fora liquid insulated electrical apparatus.
  • the bushing comprisesan electricalconductor.
  • the bushing comprises an insulator body. The electrical conduct or extends through the insulator body. The insulator body comp rises a main part.
  • the main part can also be referred to as "insulator core".
  • the main part compri ses a P2024,0265 WO N /P230255WO01 February26,2025 -3 - hollow cylinder shape.
  • the conductor extends throug h this hollow cylinder.
  • the main part compr ises one single hollow cylinder.
  • the insulator body is arranged at a distance from the electrical conducto r and is not in direct contact with the electrical conductor .
  • the main part is completely arranged a t a distance from the electrical conductor and is not i n direct contact with the electrical conductor.
  • the main part is arranged at least for the most part at a di stance from the electricalconductorand isnotin direct contact with the electrical conductor.
  • a propo rtion of 10% or less of the main part is in direct contact w ith the electrical conductor along the longitudinal axis.
  • a portion of90% ormore ofthe main part isspaced from the electrical conductor along the longitudina l axis.
  • a free space is betw een the electrical conductor and the insulator body, in par ticular between the main part and the electrical conductor.
  • the free space is configured such that in an operational con dition oil or another liquid can circulate between the electri cal conductor and the insulator body, in particular bet ween the main part and the electrical conductor.
  • the oil is in direct contact with the electric al conductor and the main part.
  • the oil is used for co oling, for example.
  • the free space enables a sufficiently good circulation of the oil between the electrical condu ctor and the insulator body and thus enables an improved hea t exchange.
  • the insulator body comprises an outer cover.
  • the ou ter cover covers the main part at least in a middle part area .
  • the P2024,0265 WO N /P230255WO01 February26,2025 -4 - cover covers the outward facing portions of the mai n part.
  • an inner side facing the conductor is n ot covered by the cover.
  • the middle part area for example, is the area between axial end sides of the main part. Axial end sides, for example, are not covered by the cover.
  • a majorityofthe outward facing portion ofthe main partis covered by the cover for example more than 75%, mo re than 80%, more than 90% or more than 95% of the outer su rface of the main part exposed to air and/or arranged outsid e the apparatusiscovered bythe cover.Anotherpartof the surface of the main part which is exposed to the in sulating liquid inside the apparatusisalso notcovered by the cover.
  • the outer cover is fixed to the main part.
  • the oute r cover is fixed to the main part.
  • the outer cover adheres fir mly to the main part.
  • the outer cover houses the main part at lea st partly.
  • the cover can also be referred to as housing or ins ulator housing.
  • the cover covers a creepage length of the bushing when installed on the electrical appara tus.
  • the main part is made of thermoplastic.
  • the thermoplastic material comprises a high elastic mod ulus and mechanical strength, even at elevated temperatures, and is resistant to thermal degradation. It is also resist ant to chemical degradation, in particular by electric ins ulation liquids, for example by transformer oil and natural or syntheticesters.
  • the thermoplastic material is at least one of polyether ether ketone (PEEK), polyphenylene sulfid e (PPS), polyphthalamide (PPA), polyethersulfone (PES), poly etherimide (PEI), polyamide (PA), and semi-aromatic polyamide.
  • PEEK polyether ether ketone
  • PPS polyphenylene sulfid e
  • PPA polyphthalamide
  • PES polyethersulfone
  • PEI poly etherimide
  • PA polyamide
  • semi-aromatic polyamide for P2024,0265 WO N /P230255WO01 February26,2025 -5 - example, the main part and/or the projecting ribs c omprise a glassfiberreinforcement.Thus,the thermoplastic material is reinforced by the glass fiber filler.
  • the thermoplastic material is one of the listed polymer ic materialsfilled with glassfibers.In particular, ceramic materials can be omitted.
  • the thermoplastic materia l enables the avoidance ofceramicsforthe main part.
  • the outer cover is made of elastomeric material.
  • the elastomeric material is a rubber or comprises rubber.
  • the elastomeric material is a self-adhesive silicone rubber or comprises a self-adhesive silicone rubber .
  • the outer cover provides a hydrophobic sur face. The outer surface of the outer cover does not easily co llect contamination and is efficiently cleaned by rainwat er during operation orin a cleaning procedure provided when servicing the bushing.
  • the elastomeric material for example is one of mold able or extrudable liquid silicone rubber, high consistency rubber, and high temperature vulcanization silicone rubber.
  • the cover is made of silicone elastomer material resistant to degradation in outdoor environment.
  • the elastomeric material is resistant to electric arc and to tracking and er osion and has a hydrophobic surface.
  • the elastomeric material features the hydrophobicity recovery and hydrophobicity tran sfer properties, which minimizes leakage currents runnin g along the surface of the insulator body in wet and pollut ed environments and reduce probability of surface disc harges or electricalbreakdown.
  • the bushing comprises a chemical bond which fixes t he cover and the main part together.
  • the elastomer cover per manently P2024,0265 WO N /P230255WO01 February26,2025 -6 - adheres to the thermoplastic main part by the chemi cal bond, thus limiting possibility of water penetrating into the interface and reducing probability of electrical br eakdown along the interface.
  • the chemicalbond isrealized between the outer cover and the main part to connect the ou ter cover and the main part together.
  • the chemic al bond is formed during curing of the elastomeric material du ring production.
  • silane-based agents that a re chemicallyreactive both with the surface ofthe thermoplastic material and with the other component s of the elastomeric material, in particular the silicone ru bber mixture and/or other constituents of the curable el astomer composition forming the elastomeric material, in pa rticular the curable silicone elastomer composition, are pro vided to establish the chemical bond.
  • the chemical bond conn ects the cover and the main part together, such that the cov er and the main part cannot be detached from each other withou t being destroyed.
  • the chemical bond is a cohesive bond bet ween the surfacesofthe coverand the main part.
  • thermoplastic for the main part
  • elastomeric material for the cover and th e chemical bond to fix the main part and the cover to each oth er
  • the thermoplastic has desired and prese t surface propertiesdirectlyafterthe molding process.
  • Self-adhesive elastomeric material in particular is suitable for low voltage usage. Faster manufacturing and low costs are realized to create a bond between the elastomeric m aterial and the thermoplastic.Forexample,the bond might notbe as strong as with the use of a separate primer but str ong enough for the requirements and needs by a low voltage usa ge.
  • thermoplastic for the main p art allows the use of self-adhesive elastomeric material, beca use these two materials bond together even without a separate primer.
  • the elastomericmaterial comprisesa self-adhesive silicone rubber or consists of a self-adhesive silicone rubb er.
  • the outer cover is made of a so-called cur able liquid silicone rubber, in particular a self-adhesi ve silicone rubber containing chemical coupling agents able to form the chemicalbond between the surface ofthe thermoplastic material and the cross-linked silicon e rubber material.
  • the elastomeric material i s a solidified liquid silicone rubber or a self-adhesiv e liquid silicone rubbercured to the solid state.
  • the chemicalcoupling agent ispartofthe elastomeric material and forms the chemical bond to the main part, in pa rticular to the thermoplastic material of the main part. Thu s, it is sufficient to apply the curable elastomeric materia l including the chemical coupling agent in a liquid s tate on the main part.
  • the cover comprises a p lanar expansion.
  • the cover comprises a thickness perpendi cular to the planar expansion.
  • the thickness is substantiall y uniform between end portions.
  • the thickness is uniform within a tolerance of5%,25% or30%.
  • the thickness is constant and the same in most of the c over, for example in more than 75%,more than 80%,more than 90% or P2024,0265 WO N /P230255WO01 February26,2025 -8 - more than 95% of the cover.
  • a thickn ess of the covertransverse to an outerside ofthe main part isbetween 0.5 mm and 5 mm.
  • the thickness maybe different.
  • the cover is obliquely flanked at the end portions and/or thicke ned in cornerportions.
  • the cover isthick enough to cover the main part and provide the desired surface properties.
  • the cover is not extra t hick in specific places to form special elements, in partic ular the cover does not thicken to build a weather shed made of the elastomericmaterialalone.
  • a wall thickness of the main part is 10 mm or less.
  • the wall thickness in most parts of the main part is 10 mm or less, for exampl e 6 mm or less,transverse to the main extension ofthe main partwhich is axial in most parts and radial or inclined at th e projecting part.
  • the insulator body comp rises a weather shed.
  • the weather shed is form ed by a projecting part of the main part which is covered b y the cover.
  • the weather shed increases the creepage length duri ng operation. It also may reduce contamination of unde rlying parts during operation.
  • the weather shed is made wi th the thermoplastic material of the main part and the ela stomeric material of the cover.
  • the cover is fixed to the ma in part such that firm adhesion is realized.
  • an arcrunning between the coverand the main part can be avoided.
  • the riskofa flashovermaking a shortcut to the P2024,0265 WO N /P230255WO01 February26,2025 -9 - long creepage length is reduced.
  • a short and cost-e fficient manufacturing process with a low material consumpti on can be realized.
  • thermoplasti c material can be realized due to the material properties of t he thermoplasticmaterial.
  • the thin wallstructure of the thermoplastic material makes the time needed for he at transfer through the wall thickness short, in parti cular the time needed to cool down the molten thermoplastic m aterial until it solidifies in the mold.
  • the projecting par t of the main part stabilizesthe weathershed.
  • the weather shed is in particular not fully made ou t of elastomeric material but made out of the combinatio n of thermoplastic material and elastomeric material. Th e shape of the weather shed is defined by the shape of the pro jecting part.
  • the projecting part provides t he mechanical characteristics the weather shed and the cover covers the surface of the insulator body exposed to the outdoor environment.
  • the cover serves to provide de sired properties to the surface of the weather shed expos ed to an outdoor environment, for example a smooth outer sur face, a resistance to tracking and erosion, a resistance to UV radiation, and/or a hydrophobic property of its sur face.
  • the thin wall structure of the main part and the we ather shed makes the creepage length large. A significant part of the creepage length runs in an area which is located be low the weather shed and is therefore hardly accessible for rain or mist water, such that electrical insulation is impr oved.
  • the projecting partof the main part is substantially covered by the cover on two o pposing main sides.
  • the projecting part comp rises an P2024,0265 WO N /P230255WO01 February26,2025 -10 - upward-facing main side and an opposite downward-fa cing main side. Both main sides, as well as a connecting side that connects the two main sides, are covered by the cov er.
  • the main part comprises two or more separate parts. The separate parts are stacked along a longitudinal axis of the conductor. It is also poss ible to provide the main part in one single piece. By provi ding the main part in one single piece, manufacturing and mo unting of the bushing can be quick and easy.
  • an upper part of the tw o parts is formed inclined downwards to overlap a lower part o f the two parts, at least in part.
  • the weather s hed is realized by the upper part.
  • the upper part forms th e weather shed which overlaps the lower part, such that the l ower part isprotected againstrain and othercontamination.
  • the two or more separate partsofthe main part are made of thermoplastic and covered with the cover made of el astomeric material.
  • the separate parts of the main part are made of thermoplastic and covered by the e lastomeric material.
  • the main part is an injectio n molded body.
  • the two or more separate parts a re each injection molded bodies. Injection molding realizes a simple, cost-effective and material-saving production of th e main part.
  • the insulator body compri ses an outer flange.
  • the outer flange projects outwards fr om the P2024,0265 WO N /P230255WO01 February26,2025 -11 - main part for a coupling with a wall for the electr ical apparatus.
  • the outerflange isan integralpartof the main part.
  • the flange providesa mounting interface for the bushing to the electrical apparatus. For example, t he bushing is fixed to the electrical apparatus at the outer f lange.
  • the outer flange is con figured to hold a gasket. This ensures that the gasket is reli ably held in place during transport, installation and/or oper ation. The gasket reliably seals the bushing and the electrica l apparatusagainstfluids.
  • the liquid insulated el ectrical apparatus comprises the bushing according to one of the embodiments described herein or according to any co mbination ofthe described embodiments.
  • the liquid insulated electrical apparatus comprisesa wallin which the bushing is installed.
  • the bushing enables the conductive path through the wall and provides an electrical insulation between the condu ctor and the wall.
  • the electrical apparatus may be a low voltage appar atus, a medium voltage apparatus and/or a high voltage appa ratus.
  • the electrical apparatus is a transform er or anotherelectricalapparatus.
  • a winding such as a transformer winding
  • the tank is filled by an insulating liqui d.
  • the method for manufact uring a bushing comprises: P2024,0265 WO N /P230255WO01 February26,2025 -12 - - injecting thermoplastic into a first mold to form a main partofan insulatorforthe bushing, - applying an elastomeric material to an outer side of the main part, wherein the elastomeric material (151) c omprises a self-adhesive liquid silicone rubber or consists of a self- adhesive liquid silicone rubber,and thereby -forming a coverofthe main part,which isfixed to the main partbya chemicalbond.
  • the main body is covered by the elastomeric materia l during production to form the cover.
  • Injection molding of the thermoplastic material enables a reliable, cost-eff ective and fast production of the main part.
  • Forming the cover on the main part allowsa simple and reliable realization ofdesired and/or preset surface properties like a smooth surf ace which is weather-resistant, resistant against contaminati on and/or hydrophobic.
  • the chemical bond realizes a stable an d reliable connection between the elastomeric material and the thermoplastic. The connection is fast, simple and e fficient to manufacture.
  • thermoplastic is injected in mol ten state and cooled to a temperature below its melting point afterwards.
  • the cover isformed using a liquid, curable elastomeric material, also referred to as e lastomer composition, which is applied onto the surface of t he main partand cured afterwardsto form the cover.
  • applying the elastomeri c material comprises: - placing the main part into a second mold and inje cting the elastomeric material into the second mold such that the elastomeric material covers the outer side of the m ain part P2024,0265 WO N /P230255WO01 February26,2025 -13 - at least in part.
  • the method comprises applying the elastomeric mater ial which comprises a chemical coupling agent.
  • the elastomeri c material which comprises a liquid silicone rubber or consist s of a liquid silicone rubberisapplied.
  • the elastomeric material which comprises a self-adhesive liquid silicone rub ber or consistsofa self-adhesive liquid silicone rubber is applied. In this case, no additional primer is nece ssary.
  • the chemical coup ling agent formsthe chemicalbond to the main part.Thus,it is sufficient to apply the elastomeric material includ ing the chemical coupling agent in a liquid state on the ma in part. The chemical bond is formed during curing of the el astomeric material to the solid state. An easy and fast produ ction of the insulatorbodyispossible.
  • the thermoplastic After the thermoplastic has been injec ted into the mold, it is cooled down below its melting tempe rature, which ishigh,typicallyhigherthan 150°C,before demolding and,according to embodiments,transferring to the second mold.
  • the liquid silicone rubber in order t o initiate its curing, has to be heated up to an elevated temp erature, typically above 100°C.
  • the heat is t ransferred from the thermoplastic to the silicone rubber, whic h significantlyreducesthe totalprocessing time.
  • the thickness of the silicone rubber c over is small and uniform.
  • Figures 1 and 2 schematically show different embodi ments of a bushing and an electricalapparatus
  • Figure 3 shows a flowchart of a method according to an embodiment.
  • the embodiment of Figure 1 in particular is applica ble for low voltage bushings100.
  • the embodimentof Figure 2 in P2024,0265 WO N /P230255WO01 February26,2025 -15 - particular is applicable for medium voltage bushing s 100. Ratings may cover AC or DC voltages. For example, a range from 0.1kV to 72.5kV, in particular from 1kV to 3.6 kV, is referred to as low voltage.
  • T he liquid 103 for example is a transformer oil 195 or a natur al or a syntheticester.
  • the bushing 100 provides an electrical connection o f the electricalapparatus200 through the wall201 from an outside to an inside.
  • the wall 201 may be on earth potentia l or at least on an electrical potential that is potentiall y differentfrom the potentialofa conductor101 of the bushing 100.
  • An insulator body 110 of the bushing 1 00 providesan electricalinsulation between the wall 201 and the electricalconductor101.
  • the insulator body 110 surrounds the electrical con ductor 101.
  • the electrical conductor 101 extends elongated through the insulator body 110 along a longitudinal axis 10 2.
  • the insulator body 110 comprises a main part 112.
  • T he main part112 comprises a hollow cylindershape 113,at leastin a part.
  • the main part112 iscoaxiallyarranged with the electricalconductor101.Forexample, a centerof the hollow cylindershape 113 isthe longitudinalaxis102.
  • the outer side 129 is arranged radially opposite the inner si de 114.
  • the innerside 114 isin contactwith the liquid 103 and the outer side 129 is not in contact with t he liquid 103.
  • the main part 112 is made of a thermoplastic materi al 115.
  • the main part 112 with the hollow cylinder shape 11 3 is, for example, manufactured by an injection molding proce ss.
  • the insulator body 110 comprises one single hollow cylindrical sleeve 113.
  • the ins ulator body 110 comprises no additional second sleeve whic h is made from thermoplastic,which iscoaxiallyarranged to the sleeve 113.
  • the main part 112 comprises one single hollow cylindrical sleeve 113 made from thermoplast ic 115.
  • the insulator body 110 comprises an outer cover 150 .
  • the outer cover 150 comprises an elastomeric material 1 51 or consists of the elastomeric material 151.
  • the elastomeric material 151 is silicone rubber which p rovides a hydrophobicsurface forthe insulatorbody110.
  • the elastomeric material 151 is chemically bonded t o the thermoplastic material 115 of the main part 112. Th e chemical bond provides a cohesive connection between the ela stomeric material 151 of the cover 150 and the thermoplastic material 115 of the main part 112.
  • the elastomeric material 151 and the outer cover 15 0 provides a hydrophobicity recovery and hydrophobicity transf er properties, which make the hydrophobic nature of it s surface P2024,0265 WO N /P230255WO01 February26,2025 -18 - persist during most of the time of operation of the bushing, also in polluted environments, thus minimizing leak age currents running along the surface of the main part 112 in wetconditions.Thus,the probabilityofa surface discharge and/or electrical breakdown is reduced by the cover 150.
  • the elastomericmaterial151 forexample isone of moldable or extrudable liquid silicone rubber, high consiste ncy rubber, and high temperature vulcanization silicone rubber.
  • the curable elastomeric material 151 i s applied in liquid form and then hardens to form the cover 1 50.
  • Self-adhesive silicone rubber can be used to produc e the outer cover 150.
  • the self-adhesiv e silicone rubber contains chemical coupling agents to form th e chemical bond between the outer side 129 of the thermoplasti c material 115 of the main part 112 and the solidified silicon e rubber.
  • silane-based agents chemically react ive both with the surface ofthe thermoplasticmaterial115 and with the other components of the elastomeric material 15 1, in particular the silicone rubber mixture and/or other constituents of the curable elastomer composition f orming the elastomeric material, in particular the curable sil icone elastomer composition, are provided to establish th e chemical bond.
  • At least a middle part area 180 of the outer side 1 29 of the main part 112 is covered by the cover 150.
  • the midd le part area 180 in particular comprises the outer side 129 between a vertical upward end at a holder 126 and the wall 20 1. Parts of the outer side 129 which could come in contact w ith the environment without the cover 150 are covered by th e cover 150.
  • the cover 150 is arranged at th e outer side 129 in areas, where a creepage length 187 exte nds between the holder 126 and the wall 201.
  • the inner side 114 of the main part 112 which is in con tact with the liquid 103 isnotcovered bythe cover150.
  • the holder 126 of the upper part 121 serves as a co mpression means for the conductor seal 140, while the externa l part of the upper part 121 serves as the weather shed 116 o f the insulatorbody110.
  • the main part 112 comprises a projecting part 181 o r a plurality of projecting parts 181.
  • the projecting p arts 181 ofthe main part112 are covered bythe cover150.
  • the projecting part181 with the cover150 thereon form a weather shed 116.
  • the weather shed elongates the cr eepage length 187 and protects other parts of the insulato r body 110 againstcontamination.
  • the cover 150 comprises a thickness 182 perpendicul ar to the outerside 129.
  • the cover150 coversthe main part 112 in a planar manner and the thickness 182 is perpendicula r to the planar extension of the cover 150.
  • the cover 150 co mprises in most parts the same thickness 182 within normal tol erances of forexample 5% orless.Forexample,the thickness 182 is constant and the same in most of the cover 150.
  • the thickness 182 of the cover 150 transverse to th e outer side 129 isbetween 0.5 mm and 5 mm.
  • the thickness maybe different in the corners, for example as connection 119 where an outer flange 118 is connected or at end portions 183, 184 ofthe cover150.
  • the end portion 183 isthe vertical end adjacent to the holder 126 and the sec ond end portion 184 isthe end adjacentto the wall201.
  • the projecting part 1 81 is covered by the cover 150 on a first main side 185 w hich is facing awayfrom the wall201.
  • the projecting part 181 is also covered by the cover 150 on a second main side 186 which isfacing the wall201.
  • the design and material of the insulator body 110 w ith the main part 112 allows a thin wall structure of the m ain part with a reduced wall thickness 124.
  • the wall thickness 124 comprises a value of 10 mm or less, f or example 6 mm orless.
  • the insulator body 110 comprises the flange 118 whi ch radiallyprojectsoutwardsfrom the outerside 129 ofthe main part 112.
  • the flange 118 is configured to prov ide a mounting of the bushing 100 to the wall 201.
  • a gask et 160 is arranged between the flange 118 and the wall 201 to provide a fluid-tightconnection.
  • the main part 112 is provided by an upper part 121 and a separate lower part 122 accord ing to embodiments.
  • the lower part 122 comprises the hollo w cylinder shape 113 and the flange 118.
  • the upper part 121 is arranged on an end of the lower part 122 facing away from th e wall 201 along the longitudinalaxis102.
  • the upperpart121 isinclined with respectto the longitudinal axis 102 and overlaps the lower part 1 22 in part.
  • the upper part 121 forms the weather shed 116 .
  • the cover 150 covers the first main side 185 which face s away from the conductor 101 as well as the second main s ide 186 which faces the conductor 101.
  • areas o f the upperpart121 directlyadjacentto the lowerpart 122 orto a conductor seal 140 are not covered by the cover 1 50.
  • those parts of the upper part 121 where the creepage length 187 extends are covered by the cove r 150.
  • the outer side 129 facing away from the conductor 1 01 of the lower part 122 is covered by the cover 150.
  • the main part 112 c omprises two projecting parts 181 covered with the cover 150 to form two weather sheds 116.
  • more than two weather sheds 216 or just one single weath er shed 116 are provided.
  • a hood 128 isprovided to pressthe conductorseal 140 againstthe sealseat125 ofthe main part112 and against the conductor 101.
  • the hood 128 is fixed to the con ductor 101.
  • the hood 128 comprises an electri cally conductive material like a metal.
  • the creepag e length 187 extends between the hood 128 and the wall 201 o r, as shown in Figure 2, a flange clamp 111 which is elec trically conductive.
  • the insulatorbody110 isfixed to the wall201 by the flange clamp 111.
  • the flange clamp is a separate part whic h is fixed to the wall201,forexample bya screw connection with the mounting element 123, and exerts a force on the fla nge 118.
  • the flange 118 is fixed between the flange clamp 11 1 and the wall201.
  • the mounting element123,forexample is a threaded stud welded to the wall of the electrical apparatus and extending through the opening and a nut threaded on the stud holdsthe flange in place.
  • the electrical conductor 101 extends only partly along the main part 112.
  • An electricallyconductive conductorextension 108 is electrically and mechanically connected with the co nductor 101 and extends further longitudinally across the w all 201.
  • the conductor 108 is made from an elec trically conductive metal. It is possible that a longer elec trical conductor 101 which extends further across the wall 201 is provided and that the conductor extension 108 is om itted.
  • Figure 3 shows a flowchart of a method for manufact uring the bushing 100 according to an embodiment.In a first step 301, the molten thermoplastic material 115 is injected i nto a first mold to form the main part 112.
  • the mold is designed such that the projecting part 181 is fo rmed at the main part 112. It is also possible that the mai n part is formed by the injection molding process without the projecting part181.
  • the step 301 comprises a plurality of first molds t o form the upper part 121 and the lower part 122 of the main p art 112 separately. P2024,0265 WO N /P230255WO01 February26,2025 -24 -
  • the curable elastomeric material 151 is applied to the outer side 129 of the main part 112, in particularto atleastthe middle partarea 180 of the outer side 129.
  • the curable elastomeric material is appli ed to the projecting part 181.
  • a curable elas tomer composition isapplied,which,aftercuring to the solid state,formsthe elastomericmaterial151.
  • the main part is cooled below a give n temperature value before step 302.
  • the cover 150 is formed by the elast omeric material 151 applied in step 302, for example by cu ring the elastomeric material to the solid state.
  • the cover 150 is fixed to the main part 112 by a chemic al bond which isformed during step 303.
  • step 302 comprises placin g the main part 112 into a second mold and injecting the curab le elastomericmaterial151 into the second mold such thatthe curable elastomeric material 151 covers the outer s ide 129 at least in part.
  • the cover 150 is made by an in jection molding process.
  • the insulator body 110 is manufact ured with a two-componentinjection molding process.
  • step 302 comprises an extrusion of t he curable elastomeric material 151 on the outer side 129 such that the curable elastomeric material 151 covers the outer s ide 129 at leastin part.
  • the step 302 comprisesan application ofthe curable elastomericmaterial151 which comprises a chemical P2024,0265 WO N /P230255WO01 February26,2025 -25 - coupling agent.
  • the chemical coupling agent is prov ided to form the chemicalbond during step 303 between the thermoplastic 115 and the elastomeric material 151.
  • a so-called self-adhesive silicone rub ber is applied during the step 302.
  • the curable elastomeri c material 151 applied during step 302, for example, is a so-c alled liquid silicone rubber containing the chemical coup ling agent able to form the chemicalbond between the surface ofthe thermoplastic material 115 and the cross-linked sil icone rubber material of the elastomeric material 151. In this case, no additional primer is necessary.
  • the chemical coupling age nt forms the chemical bond to the main part. Thus, it is suf ficient to apply the elastomeric material including the chemic al coupling agent in a liquid state on the main part 1 12.
  • the chemical bond is formed during curing of the elasto meric material 151, in particular during curing of the cu rable elastomercomposition to the solid state.
  • a primer is applied onto the outer s ide 129 during step 302 before applying the uncured elastom eric material 151.
  • the elastomeric material 151 is appli ed onto the primer.
  • the primer establishes the permanent ch emical bonding between the thermoplasticmaterial115 and the elastomeric material 151.
  • the primer c omprises constituents able to chemically react with the oute r surface 129 ofthe thermoplasticmaterial115 and with the constituents of the reactive liquid silicone rubber mixture forming the cover150.
  • the different features of the different embodiments according to Figures 1 to 3 can be combined with each other i n any P2024,0265 WO N /P230255WO01 February26,2025 -26 - combination.
  • the bushing 100 according to the diffe rent embodiments and the method for manufacturing the bu shing 100 each provide a bushing 100 which is easy to manufac ture, cost-effective and providesa reliable insulation. A short manufacturing process time and low material consump tion is possible.
  • the elastomeric material 151 in particul ar the cured self-adhesive silicone rubber, provides a des ired smooth surface.
  • a long creepage length 187 is reali zed by the weather shed 116 with a thermoplastic core formed b y the projecting part 181 and the silicone housing formed by the cover 150.
  • the self-adhesive liquid silicone rubber material provides a permanent chemical bond between the main part 112 and the cover150.Thus, a reliable bushing 100 is provided.

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  • Insulating Bodies (AREA)

Abstract

A bushing (100) for a liquid-insulated electrical apparatus (200) is disclosed. The bushing (100) comprises an electrical conductor (101) and an insulator body (110) through which the electrical conductor (101) extends, wherein the insulator body (110) comprises a main part (112) and an outer cover (150), the outer cover (150) covering the main part (112) at least in part, the main part (122) is made of thermoplastic (115) and the external cover (150) is made of elastomeric material (151), wherein the elastomeric material (1 51) comprises a self-adhesive silicone rubber or consists of a self-adhesive silicone rubber, and wherein the main part (112) and the outer cover (150) are fixed to each other by a chemical bond.

Description

P2024,0265 WO N /P230255WO01 February26,2025 -1 - Description Bushing,electricalapparatusand method The present disclosure relates to a bushing and a l iquid insulated electrical apparatus comprising the bushi ng. The electrical apparatus may be a transformer or a swit chgear, for example. The present disclosure further relates to a method for manufacturing a bushing, in particular a method formanufacturing the bushing described herein. A bushing, for example, enables a conductor to pass through a wall of an electrical apparatus, providing electric al insulation between the conductorand the wall. EP 1014388 A2 relates to a bushing insulator, whi ch comprises an insulating and supporting body which i nternally accommodates at least one conductor, a set of sheds being provided externally to the insulating and a support ing body which ismade ofpolymericmaterial. CN 212694914 U relates to a bushing, which compri ses a copper rod, an inner rigid insulating layer, a grad ing ring and an insulating umbrella skirt, the inner rigid i nsulating layer is formed on the outer side of the copper rod in an injection molding mode through thermoplastic or the rmosetting materials. SE 506172 C2 relates to an insulator. The insulato r consists of a tube which is made from a thermoplastic weldab le material. A number of pre-fabricated bushings are a pplied about the tube. The bushings are made from a rubber -like material,such ase.g.silicone rubber. P2024,0265 WO N /P230255WO01 February26,2025 -2 - JP H09161576 A relatesto an insulatorofpolymer which is composed of a core part, a body in the form of a co ping protruding from the core, and a rubber sheath layer having a certain thickness. GB 1281583 A relates to a polymeric electric insu lator sleeve,which comprisessintered particlesof polytetrafluoroethylene, or neoprene, butyl or sili cone rubber. Itisdesirable to provide a bushing thatprovides a reliable operation. It is further desirable to provide a met hod for manufacturing a bushing that is reliable and cost-e ffective. Embodimentsofthe disclosure relate to a bushing. In particular,the bushing isconfigured fora liquid insulated electrical apparatus. Further embodiments of the di sclosure relate to a liquid insulated electrical apparatus c omprising the bushing.Furtherembodimentsofthe disclosure relate to a method for manufacturing a bushing, in particular a bushing of at least one of the embodiments described herein . Every feature described with respectto the bushing,the apparatus, and the method is also disclosed herein with respec t to the other ones of the bushing, the apparatus, and the m ethod, even if the respective feature is not explicitly me ntioned in the contextofthe specificaspect. The bushing comprisesan electricalconductor.The bushing comprises an insulator body. The electrical conduct or extends through the insulator body. The insulator body comp rises a main part. The main part can also be referred to as "insulator core". For example, the main part compri ses a P2024,0265 WO N /P230255WO01 February26,2025 -3 - hollow cylinder shape. The conductor extends throug h this hollow cylinder. In particular, the main part compr ises one single hollow cylinder.Forexample,the insulator bodyis arranged at a distance from the electrical conducto r and is not in direct contact with the electrical conductor . For example, the main part is completely arranged a t a distance from the electrical conductor and is not i n direct contact with the electrical conductor. For example, the main part is arranged at least for the most part at a di stance from the electricalconductorand isnotin direct contact with the electrical conductor. For example, a propo rtion of 10% or less of the main part is in direct contact w ith the electrical conductor along the longitudinal axis. F or example,a portion of90% ormore ofthe main part isspaced from the electrical conductor along the longitudina l axis. According to some embodiments, a free space is betw een the electrical conductor and the insulator body, in par ticular between the main part and the electrical conductor. The free space is configured such that in an operational con dition oil or another liquid can circulate between the electri cal conductor and the insulator body, in particular bet ween the main part and the electrical conductor. For example , during use, the oil is in direct contact with the electric al conductor and the main part. The oil is used for co oling, for example. The free space enables a sufficiently good circulation of the oil between the electrical condu ctor and the insulator body and thus enables an improved hea t exchange. The insulator body comprises an outer cover. The ou ter cover covers the main part at least in a middle part area . The P2024,0265 WO N /P230255WO01 February26,2025 -4 - cover covers the outward facing portions of the mai n part. In particular, an inner side facing the conductor is n ot covered by the cover. The middle part area, for example, is the area between axial end sides of the main part. Axial end sides, for example, are not covered by the cover. For exam ple, a majorityofthe outward facing portion ofthe main partis covered by the cover, for example more than 75%, mo re than 80%, more than 90% or more than 95% of the outer su rface of the main part exposed to air and/or arranged outsid e the apparatusiscovered bythe cover.Anotherpartof the surface of the main part which is exposed to the in sulating liquid inside the apparatusisalso notcovered by the cover. The outer cover is fixed to the main part. The oute r cover is fixed to the main part. The outer cover adheres fir mly to the main part.The outercovercoversthe main partat least partly. The outer cover houses the main part at lea st partly. The cover can also be referred to as housing or ins ulator housing. In particular, the cover covers a creepage length of the bushing when installed on the electrical appara tus. The main part is made of thermoplastic. In particul ar, the thermoplastic material comprises a high elastic mod ulus and mechanical strength, even at elevated temperatures, and is resistant to thermal degradation. It is also resist ant to chemical degradation, in particular by electric ins ulation liquids, for example by transformer oil and natural or syntheticesters. For example, the thermoplastic material is at least one of polyether ether ketone (PEEK), polyphenylene sulfid e (PPS), polyphthalamide (PPA), polyethersulfone (PES), poly etherimide (PEI), polyamide (PA), and semi-aromatic polyamide. For P2024,0265 WO N /P230255WO01 February26,2025 -5 - example, the main part and/or the projecting ribs c omprise a glassfiberreinforcement.Thus,the thermoplastic material is reinforced by the glass fiber filler. For exampl e, the thermoplastic material is one of the listed polymer ic materialsfilled with glassfibers.In particular, ceramic materials can be omitted. The thermoplastic materia l enables the avoidance ofceramicsforthe main part. The outer cover is made of elastomeric material. In particular, the elastomeric material is a rubber or comprises rubber. The elastomeric material is a self-adhesive silicone rubber or comprises a self-adhesive silicone rubber . For example, the outer cover provides a hydrophobic sur face. The outer surface of the outer cover does not easily co llect contamination and is efficiently cleaned by rainwat er during operation orin a cleaning procedure provided when servicing the bushing. The elastomeric material for example is one of mold able or extrudable liquid silicone rubber, high consistency rubber, and high temperature vulcanization silicone rubber. The cover is made of silicone elastomer material resistant to degradation in outdoor environment. The elastomeric material is resistant to electric arc and to tracking and er osion and has a hydrophobic surface. The elastomeric material features the hydrophobicity recovery and hydrophobicity tran sfer properties, which minimizes leakage currents runnin g along the surface of the insulator body in wet and pollut ed environments and reduce probability of surface disc harges or electricalbreakdown. The bushing comprises a chemical bond which fixes t he cover and the main part together. The elastomer cover per manently P2024,0265 WO N /P230255WO01 February26,2025 -6 - adheres to the thermoplastic main part by the chemi cal bond, thus limiting possibility of water penetrating into the interface and reducing probability of electrical br eakdown along the interface.The chemicalbond isrealized between the outer cover and the main part to connect the ou ter cover and the main part together. For example, the chemic al bond is formed during curing of the elastomeric material du ring production. For example, silane-based agents that a re chemicallyreactive both with the surface ofthe thermoplastic material and with the other component s of the elastomeric material, in particular the silicone ru bber mixture and/or other constituents of the curable el astomer composition forming the elastomeric material, in pa rticular the curable silicone elastomer composition, are pro vided to establish the chemical bond. The chemical bond conn ects the cover and the main part together, such that the cov er and the main part cannot be detached from each other withou t being destroyed. The chemical bond is a cohesive bond bet ween the surfacesofthe coverand the main part. The combination of the use of the thermoplastic for the main part, the elastomeric material for the cover and th e chemical bond to fix the main part and the cover to each oth er, for example makesthe manufacturing processeasierand faster.In particular, the thermoplastic has desired and prese t surface propertiesdirectlyafterthe molding process. Self-adhesive elastomeric material in particular is suitable for low voltage usage. Faster manufacturing and low costs are realized to create a bond between the elastomeric m aterial and the thermoplastic.Forexample,the bond might notbe as strong as with the use of a separate primer but str ong enough for the requirements and needs by a low voltage usa ge. In P2024,0265 WO N /P230255WO01 February26,2025 -7 - particular, the use of thermoplastic for the main p art allows the use of self-adhesive elastomeric material, beca use these two materials bond together even without a separate primer. The elastomericmaterialcomprisesa self-adhesive silicone rubber or consists of a self-adhesive silicone rubb er. For example, the outer cover is made of a so-called cur able liquid silicone rubber, in particular a self-adhesi ve silicone rubber containing chemical coupling agents able to form the chemicalbond between the surface ofthe thermoplastic material and the cross-linked silicon e rubber material. In particular, the elastomeric material i s a solidified liquid silicone rubber or a self-adhesiv e liquid silicone rubbercured to the solid state. In the case of self-adhesive silicone rubber, no ad ditional primer or other auxiliary materials are necessary t o form the chemicalbond between the outercoverand the main bond.The chemicalcoupling agentispartofthe elastomeric material and forms the chemical bond to the main part, in pa rticular to the thermoplastic material of the main part. Thu s, it is sufficient to apply the curable elastomeric materia l including the chemical coupling agent in a liquid s tate on the main part. The chemical bond is formed during c uring of the elastomericmaterialto the solid state. According to an embodiment, the cover comprises a p lanar expansion. The cover comprises a thickness perpendi cular to the planar expansion. The thickness is substantiall y uniform between end portions. For example, the thickness is uniform within a tolerance of5%,25% or30%.Forexample, the thickness is constant and the same in most of the c over, for example in more than 75%,more than 80%,more than 90% or P2024,0265 WO N /P230255WO01 February26,2025 -8 - more than 95% of the cover. In particular, a thickn ess of the covertransverse to an outerside ofthe main part isbetween 0.5 mm and 5 mm. At the end portions and/or in corn ers, the thicknessmaybe different.Forexample,the cover is obliquely flanked at the end portions and/or thicke ned in cornerportions.In particular,the coveristhick enough to cover the main part and provide the desired surface properties. In particular, the cover is not extra t hick in specific places to form special elements, in partic ular the cover does not thicken to build a weather shed made of the elastomericmaterialalone. According to an embodiment, a wall thickness of the main part is 10 mm or less. In particular, the wall thickness in most parts of the main part is 10 mm or less, for exampl e 6 mm or less,transverse to the main extension ofthe main partwhich is axial in most parts and radial or inclined at th e projecting part. A thin-walled, material-saving and quick-to- produce main partisrealized. According to an embodiment, the insulator body comp rises a weather shed. For example, the weather shed is form ed by a projecting part of the main part which is covered b y the cover. The weather shed increases the creepage length duri ng operation. It also may reduce contamination of unde rlying parts during operation. The weather shed is made wi th the thermoplastic material of the main part and the ela stomeric material of the cover. The cover is fixed to the ma in part such that firm adhesion is realized. Thus, during o peration, an arcrunning between the coverand the main part can be avoided.The riskofa flashovermaking a shortcut to the P2024,0265 WO N /P230255WO01 February26,2025 -9 - long creepage length is reduced. A short and cost-e fficient manufacturing process with a low material consumpti on can be realized. A thin wall structure of the thermoplasti c material can be realized due to the material properties of t he thermoplasticmaterial.The thin wallstructure of the thermoplastic material makes the time needed for he at transfer through the wall thickness short, in parti cular the time needed to cool down the molten thermoplastic m aterial until it solidifies in the mold. The projecting par t of the main partstabilizesthe weathershed. The weather shed is in particular not fully made ou t of elastomeric material but made out of the combinatio n of thermoplastic material and elastomeric material. Th e shape of the weather shed is defined by the shape of the pro jecting part. In particular, the projecting part provides t he mechanical characteristics the weather shed and the cover covers the surface of the insulator body exposed to the outdoor environment. The cover serves to provide de sired properties to the surface of the weather shed expos ed to an outdoor environment, for example a smooth outer sur face, a resistance to tracking and erosion, a resistance to UV radiation, and/or a hydrophobic property of its sur face. The thin wall structure of the main part and the we ather shed makes the creepage length large. A significant part of the creepage length runs in an area which is located be low the weather shed and is therefore hardly accessible for rain or mist water, such that electrical insulation is impr oved. According to an embodiment,the projecting partof the main part is substantially covered by the cover on two o pposing main sides. In particular, the projecting part comp rises an P2024,0265 WO N /P230255WO01 February26,2025 -10 - upward-facing main side and an opposite downward-fa cing main side. Both main sides, as well as a connecting side that connects the two main sides, are covered by the cov er. According to an embodiment, the main part comprises two or more separate parts. The separate parts are stacked along a longitudinal axis of the conductor. It is also poss ible to provide the main part in one single piece. By provi ding the main part in one single piece, manufacturing and mo unting of the bushing can be quick and easy. Providing the ma in part with two or more separate parts, for example, enabl es a greater freedom of design. Different functionalitie s can be realized in different parts of the two or more sepa rate parts. According to an embodiment, an upper part of the tw o parts is formed inclined downwards to overlap a lower part o f the two parts, at least in part. For example, the weather s hed is realized by the upper part. The upper part forms th e weather shed which overlaps the lower part, such that the l ower part isprotected againstrain and othercontamination. The two or more separate partsofthe main partare made of thermoplastic and covered with the cover made of el astomeric material. For example, all of the separate parts of the main part are made of thermoplastic and covered by the e lastomeric material. For example, the main part is an injectio n molded body. For example, the two or more separate parts a re each injection molded bodies. Injection molding realizes a simple, cost-effective and material-saving production of th e main part. According to embodiments, the insulator body compri ses an outer flange. The outer flange projects outwards fr om the P2024,0265 WO N /P230255WO01 February26,2025 -11 - main part for a coupling with a wall for the electr ical apparatus.The outerflange isan integralpartof the main part.The flange providesa mounting interface for the bushing to the electrical apparatus. For example, t he bushing is fixed to the electrical apparatus at the outer f lange. According to an embodiment, the outer flange is con figured to hold a gasket. This ensures that the gasket is reli ably held in place during transport, installation and/or oper ation. The gasket reliably seals the bushing and the electrica l apparatusagainstfluids. According to an embodiment, the liquid insulated el ectrical apparatus comprises the bushing according to one of the embodiments described herein or according to any co mbination ofthe described embodiments.The liquid insulated electrical apparatuscomprisesa wallin which the bushing is installed. The bushing enables the conductive path through the wall and provides an electrical insulation between the condu ctor and the wall. The electrical apparatus may be a low voltage appar atus, a medium voltage apparatus and/or a high voltage appa ratus. As an example, the electrical apparatus is a transform er or anotherelectricalapparatus. The electricalapparatuscomprisesa tankin which one or more electrical functional elements are located. Fo r example, a winding, such as a transformer winding, may be lo cated in the tank. The tank is filled by an insulating liqui d. According to an embodiment, the method for manufact uring a bushing comprises: P2024,0265 WO N /P230255WO01 February26,2025 -12 - - injecting thermoplastic into a first mold to form a main partofan insulatorforthe bushing, - applying an elastomeric material to an outer side of the main part, wherein the elastomeric material (151) c omprises a self-adhesive liquid silicone rubber or consists of a self- adhesive liquid silicone rubber,and thereby -forming a coverofthe main part,which isfixed to the main partbya chemicalbond. The main body is covered by the elastomeric materia l during production to form the cover.Injection molding of the thermoplastic material enables a reliable, cost-eff ective and fast production of the main part. Forming the cover on the main partallowsa simple and reliable realization ofdesired and/or preset surface properties like a smooth surf ace which is weather-resistant, resistant against contaminati on and/or hydrophobic. The chemical bond realizes a stable an d reliable connection between the elastomeric material and the thermoplastic. The connection is fast, simple and e fficient to manufacture. In particular, the thermoplastic is injected in mol ten state and cooled to a temperature below its melting point afterwards.Forexample,the coverisformed using a liquid, curable elastomeric material, also referred to as e lastomer composition, which is applied onto the surface of t he main partand cured afterwardsto form the cover. According to an embodiment, applying the elastomeri c material comprises: - placing the main part into a second mold and inje cting the elastomeric material into the second mold such that the elastomeric material covers the outer side of the m ain part P2024,0265 WO N /P230255WO01 February26,2025 -13 - at least in part. Thus, the insulator body with the chemical bond is manufactured with a two-component injection molding process. According to an alternative embodiment, applying th e elastomericmaterialcomprises: - extruding the elastomeric material on the outer s ide of the main part such that the elastomeric material covers the outer side atleastin part.The elastomericmaterialis extruded around the surface of the main part to form the cov er. The method comprises applying the elastomeric mater ial which comprises a chemical coupling agent. The elastomeri c material which comprises a liquid silicone rubber or consist s of a liquid silicone rubberisapplied.The elastomeric material which comprises a self-adhesive liquid silicone rub ber or consistsofa self-adhesive liquid silicone rubber is applied. In this case, no additional primer is nece ssary. As part of the elastomeric material, the chemical coup ling agent formsthe chemicalbond to the main part.Thus,it is sufficient to apply the elastomeric material includ ing the chemical coupling agent in a liquid state on the ma in part. The chemical bond is formed during curing of the el astomeric material to the solid state. An easy and fast produ ction of the insulatorbodyispossible. For example, after the thermoplastic has been injec ted into the mold, it is cooled down below its melting tempe rature, which ishigh,typicallyhigherthan 150°C,before demolding and,according to embodiments,transferring to the second mold. P2024,0265 WO N /P230255WO01 February26,2025 -14 - For example, the liquid silicone rubber, in order t o initiate its curing, has to be heated up to an elevated temp erature, typically above 100°C. When the liquid silicone rub ber is injected onto that hot thermoplastic, the heat is t ransferred from the thermoplastic to the silicone rubber, whic h significantlyreducesthe totalprocessing time. For example, the thickness of the silicone rubber c over is small and uniform. This shortens the time of heat t ransfer to the silicone rubber needed to heat it up to the cur ing temperature. Hereinafter,the bushing,the electricalapparatus and the method will be explained in more detail with refere nce to the drawings on the basis of exemplary embodiments. The accompanying figures are included to provide a furt her understanding. In the figures, elements of the same structure and/or functionality may be referred to by the same reference signs.Itisto be understood thatthe embodiments shown in the figures are illustrative representations and ar e not necessarilydrawn to scale.Insofaraselementsor components correspond to one another in terms of their functio n in different figures, the description thereof is not n ecessarily repeated foreach ofthe following figures. Figures 1 and 2 schematically show different embodi ments of a bushing and an electricalapparatus,and Figure 3 shows a flowchart of a method according to an embodiment. The embodiment of Figure 1 in particular is applica ble for low voltage bushings100.The embodimentofFigure 2 in P2024,0265 WO N /P230255WO01 February26,2025 -15 - particular is applicable for medium voltage bushing s 100. Ratings may cover AC or DC voltages. For example, a range from 0.1kV to 72.5kV, in particular from 1kV to 3.6 kV, is referred to as low voltage. For example, a range fr om 3kV to 72.5kV is referred to as medium voltage (MV), in pa rticular lager than 3.6 kV. For example, current rating is f rom 100 A to 10000 A. Figures1 and 2 each schematicallyshow a vertical section of the bushing 100 according to different embodiments. In particular, the bushing 100 comprises a rotationall y symmetricaland/ormirror-symmetricalshape. The bushing 100 is shown installed in a wall 201 of an electricalapparatus200.The electricalapparatus 200 for example isa liquid insulated electricalapparatus like a transformerora reactor.An insulating liquid 103 is arranged in a tank which is bonded by a wall 201. T he liquid 103 for example is a transformer oil 195 or a natur al or a syntheticester. The bushing 100 provides an electrical connection o f the electricalapparatus200 through the wall201 from an outside to an inside. The wall 201 may be on earth potentia l or at least on an electrical potential that is potentiall y differentfrom the potentialofa conductor101 of the bushing 100. An insulator body 110 of the bushing 1 00 providesan electricalinsulation between the wall 201 and the electricalconductor101. The insulator body 110 surrounds the electrical con ductor 101. The electrical conductor 101 extends elongated through the insulator body 110 along a longitudinal axis 10 2. A part P2024,0265 WO N /P230255WO01 February26,2025 -16 - of the insulator body 110 is exposed to the air env ironment, typicallyoutdoorenvironment,and anotherpartof the insulator body 110 is immersed in the insulating li quid 103 ofthe apparatus200. The insulator body 110 comprises a main part 112. T he main part112 comprisesa hollow cylindershape 113,at leastin a part.The main part112 iscoaxiallyarranged with the electricalconductor101.Forexample,a centerof the hollow cylindershape 113 isthe longitudinalaxis102. The insulatorbody110 comprisesan innerside 114 which facesthe electricalconductor101.The innerside 114 extendsalong the longitudinalaxis102. The inner side 114 is arranged at a distance to the electrical conductor 101, such that a free space 19 0 is provided between the insulator body 110 and the ele ctrical conductor101.The innerside 114,which facesthe electrical conductor 101, is arranged spaced apart from the el ectrical conductor 101. The inner side 114 and the electrica l conductor 101 are not in direct contact with each o ther. In particular,the free space 190 isprovided between the main part112 and the electricalconductor101.The oil 195 or another liquid 103 which is provided inside the ele ctrical apparatus 200 for cooling and/or insulation can cir culate between the insulator body 110 and the electrical c onductor 101 in the free space 190, in particular between th e inner side 114 and the electrical conductor 101. The free space 190 allows good heat exchange between the conductor 101 and the oil 195 as the oil 195 can circulate around the ele ctrical conductor101 in the free space 190. P2024,0265 WO N /P230255WO01 February26,2025 -17 - The insulator body 110 comprises an outer side 129. The outer side 129 is arranged radially opposite the inner si de 114. Forexample,the innerside 114 isin contactwith the liquid 103 and the outer side 129 is not in contact with t he liquid 103. The main part 112 is made of a thermoplastic materi al 115. The main part 112 with the hollow cylinder shape 11 3 is, for example, manufactured by an injection molding proce ss. In particular, the insulator body 110 comprises one single hollow cylindrical sleeve 113. For example, the ins ulator body 110 comprises no additional second sleeve whic h is made from thermoplastic,which iscoaxiallyarranged to the sleeve 113. In particular, the main part 112 comprises one single hollow cylindrical sleeve 113 made from thermoplast ic 115. The insulator body 110 comprises an outer cover 150 . The outer cover 150 comprises an elastomeric material 1 51 or consists of the elastomeric material 151. For examp le, the elastomeric material 151 is silicone rubber which p rovides a hydrophobicsurface forthe insulatorbody110. The elastomeric material 151 is chemically bonded t o the thermoplastic material 115 of the main part 112. Th e chemical bond provides a cohesive connection between the ela stomeric material 151 of the cover 150 and the thermoplastic material 115 of the main part 112. In particular, the connec tion cannotbe detached non-destructively. The elastomeric material 151 and the outer cover 15 0 provides a hydrophobicity recovery and hydrophobicity transf er properties, which make the hydrophobic nature of it s surface P2024,0265 WO N /P230255WO01 February26,2025 -18 - persist during most of the time of operation of the bushing, also in polluted environments, thus minimizing leak age currents running along the surface of the main part 112 in wetconditions.Thus,the probabilityofa surface discharge and/or electrical breakdown is reduced by the cover 150. The processofhydrophobicityrecovery,afteran event rendering the silicone rubber surface less hydrophobic or eve n hydrophilic, such as activity of plasma generated b y neighboring electricarcoran extreme rainfallof long duration, is described, for example, in D. Bodas an d C. Khan- Malek, Sens. Actuators B: Chem. vol. 123, p. 368 (2 007). The process of hydrophobicity transfer, i.e., transferr ing the hydrophobicpropertiesofthe silicone rubberonto the pollution layers accumulating on its surface during service ofthe insulator,isdescribed,forexample,in A. Hergert, etal.,IEEE Trans.Dielectr.Electr.Insul.,vol. 24,no.2, p.1057 (2017). The elastomericmaterial151 forexample isone of moldable or extrudable liquid silicone rubber, high consiste ncy rubber, and high temperature vulcanization silicone rubber. For example, the curable elastomeric material 151 i s applied in liquid form and then hardens to form the cover 1 50. Self-adhesive silicone rubber can be used to produc e the outer cover 150. Without being bound to it, example s for self-adhesive silicone rubber are described in EP 0 497349, US 4,742,103,EP 0493791 A1,EP 0497349 B1,US 5,595,826, EP 0875536 B1, US 6,743,515 B1, US 2003/0236380 A 1, and US 2005/0089696A1, the contents of which are hereby in corporated by reference. Other examples include SILASTIC™ SA 9 940 compositions from Dow Chemical Company, Silopren™ L SR 2740 from Momentive Performance Materials Inc., or ELAST OSIL® LR P2024,0265 WO N /P230255WO01 February26,2025 -19 - 3070 grades from Wacker Chemie AG. The self-adhesiv e silicone rubber contains chemical coupling agents to form th e chemical bond between the outer side 129 of the thermoplasti c material 115 of the main part 112 and the solidified silicon e rubber. In particular, silane-based agents chemically react ive both with the surface ofthe thermoplasticmaterial115 and with the other components of the elastomeric material 15 1, in particular the silicone rubber mixture and/or other constituents of the curable elastomer composition f orming the elastomeric material, in particular the curable sil icone elastomer composition, are provided to establish th e chemical bond. At least a middle part area 180 of the outer side 1 29 of the main part 112 is covered by the cover 150. The midd le part area 180 in particular comprises the outer side 129 between a vertical upward end at a holder 126 and the wall 20 1. Parts of the outer side 129 which could come in contact w ith the environment without the cover 150 are covered by th e cover 150. In particular, the cover 150 is arranged at th e outer side 129 in areas, where a creepage length 187 exte nds between the holder 126 and the wall 201. For exampl e, the inner side 114 of the main part 112 which is in con tact with the liquid 103 isnotcovered bythe cover150. The holder 126 of the upper part 121 serves as a co mpression means for the conductor seal 140, while the externa l part of the upper part 121 serves as the weather shed 116 o f the insulatorbody110. The main part 112 comprises a projecting part 181 o r a plurality of projecting parts 181. The projecting p arts 181 ofthe main part112 are covered bythe cover150. P2024,0265 WO N /P230255WO01 February26,2025 -20 - The projecting part181 with the cover150 thereon form a weather shed 116. The weather shed elongates the cr eepage length 187 and protects other parts of the insulato r body 110 againstcontamination. The cover 150 comprises a thickness 182 perpendicul ar to the outerside 129.The cover150 coversthe main part 112 in a planar manner and the thickness 182 is perpendicula r to the planar extension of the cover 150. The cover 150 co mprises in most parts the same thickness 182 within normal tol erances of forexample 5% orless.Forexample,the thickness 182 is constant and the same in most of the cover 150. For example, the thickness 182 of the cover 150 transverse to th e outer side 129 isbetween 0.5 mm and 5 mm.The thickness maybe different in the corners, for example as connection 119 where an outer flange 118 is connected or at end portions 183, 184 ofthe cover150.Forexample,the end portion 183 isthe vertical end adjacent to the holder 126 and the sec ond end portion 184 isthe end adjacentto the wall201. To form the weather shed 116, the projecting part 1 81 is covered by the cover 150 on a first main side 185 w hich is facing awayfrom the wall201.The projecting part 181 is also covered by the cover 150 on a second main side 186 which isfacing the wall201. The design and material of the insulator body 110 w ith the main part 112 allows a thin wall structure of the m ain part with a reduced wall thickness 124. For example, the wall thickness 124 comprises a value of 10 mm or less, f or example 6 mm orless. P2024,0265 WO N /P230255WO01 February26,2025 -21 - The insulator body 110 comprises the flange 118 whi ch radiallyprojectsoutwardsfrom the outerside 129 ofthe main part 112. The flange 118 is configured to prov ide a mounting of the bushing 100 to the wall 201. A gask et 160 is arranged between the flange 118 and the wall 201 to provide a fluid-tightconnection. As shown in Figure 1, the main part 112 is provided by an upper part 121 and a separate lower part 122 accord ing to embodiments. The lower part 122 comprises the hollo w cylinder shape 113 and the flange 118. The upper part 121 is arranged on an end of the lower part 122 facing away from th e wall 201 along the longitudinalaxis102. The upperpart121 isinclined with respectto the longitudinal axis 102 and overlaps the lower part 1 22 in part. The upper part 121 forms the weather shed 116 . The cover 150 covers the first main side 185 which face s away from the conductor 101 as well as the second main s ide 186 which faces the conductor 101. For example, areas o f the upperpart121 directlyadjacentto the lowerpart 122 orto a conductor seal 140 are not covered by the cover 1 50. In particular, those parts of the upper part 121 where the creepage length 187 extends are covered by the cove r 150. The outer side 129 facing away from the conductor 1 01 of the lower part 122 is covered by the cover 150. In addi tion, the flange 118, in particular on those parts facing awa y from the wall 201 and facing away from the conductor 101, is covered bythe cover150.Thus,the whole extension ofthe creepage length 187 between the holder126 and the wall201 iscovered bythe cover150,exceptpossiblya narrow gap 109 between the upperpart121 and the lowerpart122.The gap 109 is P2024,0265 WO N /P230255WO01 February26,2025 -22 - small enough such that the creepage length 187 does not extend through the gap 109. The upper part 121 is fixed to the conductor 101 by the holder 126. During manufacturing, the lower part 12 2 is arranged on the wall 201 such that the flange 118 i s supported on the wall 201. Inside the tank, the con ductor 101 is supported via an insulating support 107 at the w all 201. The conductor seal 140 is arranged on the conductor 101 and pressed verticallyalong the longitudinalaxis102 againsta seal seat 125 of the lower part 122 by the upper pa rt 121. Thiscompression force ismaintained byfixing the upperpart 121 with the holder126 atthe conductor101. The transition between the upper part 121 and the l ower part 122 at the gap 109 is sealed via the conductor seal 140. Figure 2 schematically shows an embodiment with the main part 112 formed of one single piece. The main part 112 c omprises two projecting parts 181 covered with the cover 150 to form two weather sheds 116. According to further embodim ents, more than two weather sheds 216 or just one single weath er shed 116 are provided. A hood 128 isprovided to pressthe conductorseal 140 againstthe sealseat125 ofthe main part112 and against the conductor 101. The hood 128 is fixed to the con ductor 101. For example, the hood 128 comprises an electri cally conductive material like a metal. Thus, the creepag e length 187 extends between the hood 128 and the wall 201 o r, as shown in Figure 2, a flange clamp 111 which is elec trically conductive. P2024,0265 WO N /P230255WO01 February26,2025 -23 - The insulatorbody110 isfixed to the wall201 by the flange clamp 111. The flange clamp is a separate part whic h is fixed to the wall201,forexample bya screw connection with the mounting element 123, and exerts a force on the fla nge 118. The flange 118 is fixed between the flange clamp 11 1 and the wall201.The mounting element123,forexample is a threaded stud welded to the wall of the electrical apparatus and extending through the opening and a nut threaded on the stud holdsthe flange in place. In the embodiment shown in Figure 2, the electrical conductor 101 extends only partly along the main part 112. An electricallyconductive conductorextension 108 is electrically and mechanically connected with the co nductor 101 and extends further longitudinally across the w all 201. For example, the conductor 108 is made from an elec trically conductive metal. It is possible that a longer elec trical conductor 101 which extends further across the wall 201 is provided and that the conductor extension 108 is om itted. Figure 3 shows a flowchart of a method for manufact uring the bushing 100 according to an embodiment.In a first step 301, the molten thermoplastic material 115 is injected i nto a first mold to form the main part 112. In particular , the mold is designed such that the projecting part 181 is fo rmed at the main part 112. It is also possible that the mai n part is formed by the injection molding process without the projecting part181. To form the bushing according to the embodimentof Figure 1, the step 301 comprises a plurality of first molds t o form the upper part 121 and the lower part 122 of the main p art 112 separately. P2024,0265 WO N /P230255WO01 February26,2025 -24 - In a step 302, the curable elastomeric material 151 is applied to the outer side 129 of the main part 112, in particularto atleastthe middle partarea 180 of the outer side 129. The curable elastomeric material is appli ed to the projecting part 181. In other words, a curable elas tomer composition isapplied,which,aftercuring to the solid state,formsthe elastomericmaterial151. In particular, the main part is cooled below a give n temperature value before step 302. In a step 303, the cover 150 is formed by the elast omeric material 151 applied in step 302, for example by cu ring the elastomeric material to the solid state. For exampl e, the cover 150 is fixed to the main part 112 by a chemic al bond which isformed during step 303. According to embodiments, step 302 comprises placin g the main part 112 into a second mold and injecting the curab le elastomericmaterial151 into the second mold such thatthe curable elastomeric material 151 covers the outer s ide 129 at least in part. Thus, the cover 150 is made by an in jection molding process. The insulator body 110 is manufact ured with a two-componentinjection molding process. Alternatively, step 302 comprises an extrusion of t he curable elastomeric material 151 on the outer side 129 such that the curable elastomeric material 151 covers the outer s ide 129 at leastin part. Forexample,the step 302 comprisesan application ofthe curable elastomericmaterial151 which comprisesa chemical P2024,0265 WO N /P230255WO01 February26,2025 -25 - coupling agent. The chemical coupling agent is prov ided to form the chemicalbond during step 303 between the thermoplastic 115 and the elastomeric material 151. For example, a so-called self-adhesive silicone rub ber is applied during the step 302. The curable elastomeri c material 151 applied during step 302, for example, is a so-c alled liquid silicone rubber containing the chemical coup ling agent able to form the chemicalbond between the surface ofthe thermoplastic material 115 and the cross-linked sil icone rubber material of the elastomeric material 151. In this case, no additional primer is necessary. As part of the elastomeric material 151, the chemical coupling age nt forms the chemical bond to the main part. Thus, it is suf ficient to apply the elastomeric material including the chemic al coupling agent in a liquid state on the main part 1 12. The chemical bond is formed during curing of the elasto meric material 151, in particular during curing of the cu rable elastomercomposition to the solid state. Alternatively, a primer is applied onto the outer s ide 129 during step 302 before applying the uncured elastom eric material 151. The elastomeric material 151 is appli ed onto the primer. The primer establishes the permanent ch emical bonding between the thermoplasticmaterial115 and the elastomeric material 151. For example, the primer c omprises constituents able to chemically react with the oute r surface 129 ofthe thermoplasticmaterial115 and with the constituents of the reactive liquid silicone rubber mixture forming the cover150. The different features of the different embodiments according to Figures 1 to 3 can be combined with each other i n any P2024,0265 WO N /P230255WO01 February26,2025 -26 - combination. The bushing 100 according to the diffe rent embodiments and the method for manufacturing the bu shing 100 each provide a bushing 100 which is easy to manufac ture, cost-effective and providesa reliable insulation. A short manufacturing process time and low material consump tion is possible. The elastomeric material 151, in particul ar the cured self-adhesive silicone rubber, provides a des ired smooth surface. A long creepage length 187 is reali zed by the weather shed 116 with a thermoplastic core formed b y the projecting part 181 and the silicone housing formed by the cover 150. The self-adhesive liquid silicone rubber material provides a permanent chemical bond between the main part 112 and the cover150.Thus,a reliable bushing 100 is provided.
P2024,0265 WO N /P230255WO01 February26,2025 -27 - Reference Signs 100 bushing 101 electricalconductor 102 longitudinalaxis 103 liquid 107 support 108 conductorextension 109 gap 110 insulatorbody 111 flange clamp 112 main part 113 hollow cylindershape 114 innerside 115 thermoplasticmaterial 116 weathershed 118 outerflange 119 connection 121 upperpart 122 lowerpart 123 mounting element 124 wallthickness 125 sealseat 126 holder 128 hood 129 outerside 140 conductorseal 150 outercover 151 elastomericmaterial 160 gasket 180 middle partarea 181 projecting part 182 thickness P2024,0265 WO N /P230255WO01 February26,2025 -28 - 183 firstend portion 184 second end portion 185 firstmain side 186 second main side 187 creepage length 190 free space 195 oil 200 electricalapparatus 201 wall 301-303 method steps

Claims

P2024,0265 WO N /P230255WO01 February26,2025 -29 - Claims 1. A bushing (100) for a liquid-insulated electrica l apparatus(200),the bushing (100)comprising an electrical conductor (101) and an insulator body (110) through which the electrical conductor (101) extend s, wherein the insulator body (110) comprises a main part (112 ) and an outer cover (150), the outer cover (150) covering t he main part (112) at least in part, the main part (122) is made of thermoplastic (115) and the external cover (150) is made of elastomeric material (151), wherein the elastomeric material (151)comprisesa self-adhesive silicone rubberor consists of a self-adhesive silicone rubber, and wherein the main part (112) and the outer cover (150) are fixed to each o ther by a chemicalbond. 2.The bushing ofthe preceding claim,wherein the cover (150)comprisesa planarexpansion and a thickness (182) perpendicular to the planar expansion, the thicknes s (182) being substantially uniform between end portions (1 83, 184). 3. The bushing of any of the preceding claims, wher ein the insulator body (110) comprises a weather shed (116) , the weather shed (116) being formed by a projecting par t (181) of the main part (112) which is covered by the cover ( 150). 4. The bushing of any of the preceding claims, wher ein the main part (112) comprises two or more separate part s (121, 122) stacked along a longitudinal axis (102) of the conductor (108), wherein the two or more parts (121, 122) are covered bythe cover(150)atleastin part. P2024,0265 WO N /P230255WO01 February26,2025 -30 - 5. A liquid-insulated electrical apparatus (200) co mprising the bushing (100) according to any one of the prece ding claimsand a wall(201)in which the bushing (100) is installed. 6. A method for manufacturing a bushing (100), comp rising: - injecting thermoplastic (115) into a first mold t o form a main part (112) of an insulator for the bushing (10 0), - applying an elastomeric material (151) to an oute r side (129) of the main part (112), wherein the elastomer ic material (151) comprises a self-adhesive liquid sil icone rubber or consists of a self-adhesive liquid silico ne rubber, and thereby - forming a cover (150) of the main part (112), whi ch is fixed to the main part(112)bya chemicalbond. 7. The method of claim 6, wherein applying the elas tomeric material(151)comprises: - placing the main part (112) into a second mold an d injecting the elastomeric material (151) into the s econd mold such that the elastomeric material (151) covers the outer side (129) of the main part (112) at least in part, or - extruding the elastomeric material (151) on the o uter side (129) of the main part (112) such that the elastome ric material (151) covers the outer side (129) at least in part.
PCT/EP2025/055182 2024-03-27 2025-02-26 Bushing, electrical apparatus and method Pending WO2025201784A1 (en)

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EP24166803.7 2024-03-27
EP24166803.7A EP4625444A1 (en) 2024-03-27 2024-03-27 Bushing, electrical apparatus and method

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Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1281583A (en) 1969-07-02 1972-07-12 British Insulated Callenders Improvements in or relating to electric insulators
US4742103A (en) 1986-04-11 1988-05-03 Toray Silicone Co., Ltd. Curable organopolysiloxane compositions exhibiting improved adhesion
EP0493791A1 (en) 1990-12-25 1992-07-08 Dow Corning Toray Silicone Company, Limited Curable organopolysiloxane composition exhibiting improved adhesion in the cured form
EP0497349A2 (en) 1991-01-30 1992-08-05 Dow Corning Toray Silicone Company, Limited Organosiloxane compositions exhibiting improved adhesion
US5595826A (en) 1995-10-11 1997-01-21 Dow Corning Corporation Curable organopolysiloxane compositions with improved adhesion
JPH09161576A (en) 1995-12-12 1997-06-20 Ngk Insulators Ltd Composite insulator and its manufacture
SE506172C2 (en) 1996-02-29 1997-11-17 Ramkiw Ab Device for insulation of high voltage conductors
EP1014388A2 (en) 1998-12-15 2000-06-28 ABB Ricerca SpA Bushing insulator
US20030236380A1 (en) 2002-06-14 2003-12-25 Wacker-Chemie Gmbh Self-adhesive addition-crosslinking silicon compositions
EP0875536B1 (en) 1997-05-02 2004-03-24 GE Bayer Silicones GmbH & Co. KG Addition reaction-curing silicone elastomer compositions,process for their production, process for the production of composite mouldings and their use
US6743515B1 (en) 1999-12-09 2004-06-01 Wacker-Chemie Gmbh Self-adhesive addition-crosslinking silicone compositions
US20050089696A1 (en) 2002-02-06 2005-04-28 Ge Bayer Silicones Gmbh & Co. Kg Self-adhesive, addition cross-linking silicone-rubber blends, method for their production, method for producing composite moulded parts and use of the latter
CN212694914U (en) 2020-09-10 2021-03-12 重庆铧鸿电力设备有限公司 Temperature rise-free composite high-voltage bushing of grading ring

Patent Citations (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1281583A (en) 1969-07-02 1972-07-12 British Insulated Callenders Improvements in or relating to electric insulators
US4742103A (en) 1986-04-11 1988-05-03 Toray Silicone Co., Ltd. Curable organopolysiloxane compositions exhibiting improved adhesion
EP0493791A1 (en) 1990-12-25 1992-07-08 Dow Corning Toray Silicone Company, Limited Curable organopolysiloxane composition exhibiting improved adhesion in the cured form
EP0497349A2 (en) 1991-01-30 1992-08-05 Dow Corning Toray Silicone Company, Limited Organosiloxane compositions exhibiting improved adhesion
EP0497349B1 (en) 1991-01-30 1996-06-12 Dow Corning Toray Silicone Company, Limited Organosiloxane compositions exhibiting improved adhesion
US5595826A (en) 1995-10-11 1997-01-21 Dow Corning Corporation Curable organopolysiloxane compositions with improved adhesion
JPH09161576A (en) 1995-12-12 1997-06-20 Ngk Insulators Ltd Composite insulator and its manufacture
SE506172C2 (en) 1996-02-29 1997-11-17 Ramkiw Ab Device for insulation of high voltage conductors
EP0875536B1 (en) 1997-05-02 2004-03-24 GE Bayer Silicones GmbH & Co. KG Addition reaction-curing silicone elastomer compositions,process for their production, process for the production of composite mouldings and their use
EP1014388A2 (en) 1998-12-15 2000-06-28 ABB Ricerca SpA Bushing insulator
US6743515B1 (en) 1999-12-09 2004-06-01 Wacker-Chemie Gmbh Self-adhesive addition-crosslinking silicone compositions
US20050089696A1 (en) 2002-02-06 2005-04-28 Ge Bayer Silicones Gmbh & Co. Kg Self-adhesive, addition cross-linking silicone-rubber blends, method for their production, method for producing composite moulded parts and use of the latter
US20030236380A1 (en) 2002-06-14 2003-12-25 Wacker-Chemie Gmbh Self-adhesive addition-crosslinking silicon compositions
CN212694914U (en) 2020-09-10 2021-03-12 重庆铧鸿电力设备有限公司 Temperature rise-free composite high-voltage bushing of grading ring

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
A. HERGERT ET AL., IEEE TRANS. DIELECTR. ELECTR. INSUL., vol. 24, no. 2, 2017, pages 1057
D. BODASC. KHAN-MALEK: "Sens. Actuators B: Chem.", vol. 123, 2007, pages: 368

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