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
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
  • H01B3/002—Inhomogeneous material in general
  • H01B3/004—Inhomogeneous material in general with conductive additives or conductive layers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B7/00—Insulated conductors or cables characterised by their form
  • H01B7/17—Protection against damage caused by external factors, e.g. sheaths or armouring
  • H01B7/29—Protection against damage caused by extremes of temperature or by flame
  • H01B7/292—Protection against damage caused by extremes of temperature or by flame using material resistant to heat
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K9/00—Arrangements for cooling or ventilating
  • H02K9/22—Arrangements for cooling or ventilating by solid heat conducting material embedded in, or arranged in contact with, the stator or rotor, e.g. heat bridges
  • H02K9/223—Heat bridges

Definitions

• the invention relates to an end corona protection device, wherein on an electrically insulating sheath of an electrically conductive wire or rod as
• End corrugation an electrically conductive coating is arranged.
• the invention also relates to a method for producing an end corona shielding for an electrically iso ⁇ -regulating jacket of electrical conducting element.
• An end corona protection of the type mentioned is known for example from EP 2362399 AI.
• live cables and conductor bars must have electrical insulation, which is shielded with an inner and an outer conductive layer against cavities and detachments from ⁇ .
• Examples of such electric high-voltage clamping ⁇ devices are electric generators, electric motor ⁇ reindeer, transformers, bushings and electrical cables.
• Thematic with a ground conductive layer is also called outer corona (AGS) ⁇ be distinguished.
• AGS outer corona
• the outgoing from the cable or conductor bar electric potential is so degraded in the main insulation being ⁇ from the inner potential control toêtglimm- protection.
• one end of the guide In order to connect a cable or a conductor bar of a resource with another electrical arrangement, one end of the guide must be stripped. At the stripped end, it is then not possible to control the electric field by means of the internal potential control, the main insulation and the external corona protection in its course in a desired manner.
• an end corona shielding or cable termination can be fitted on the insulation between the grounded external corona shielding and the stripped cable end.
• Such an end corona protection consists of a resistive potential or field control, ie an end corona protection, like the adjacent external corona protection, is electrically conductive, but has a higher electrical resistance than the external corona protection.
• the aim of a potential control by means of an end corona protection is to obtain a less steep profile of the surface potential of the main insulation in the transition region between the grounded external corona shielding and the stripped end of the cable or conductor bar.
• An end corona can z. B.
• Subconductivity here is understood as a conductivity that lower than that of a metallic conductor and larger than that of an electrical insulator.
• the above document also discloses a suitable one
• the Endenglimmschutz one hand, and the surface of the metal ⁇ metallic guide element on the other hand form of an electrical capacitance.
• the insulation of the cable represents the dielectric.
• the high voltage is an alternating voltage
• an alternating current flows permanently from the end corona protection into the adjacent, grounded external corona protection. This leads to a heating of Endenglimmtikes and thus to its undesirable rapid aging in the form of z.
• the end corona protection can even overheat and thereby be damaged.
• the object of the present invention is to provide a robust end corona protection for a high-voltage device.
• the object is achieved by a Endenglimmschutzvoroplasty according to claim 1, a high voltage device according to claim 13 and a method according to claim 14.
• Advantageous developments of the invention are given by the dependent claims.
• the Endeglimmstoffvoroplasty invention can be used as a substitute for any conventional Endenglimmschutz in which an end corona protection effecting, electrically conductive coating on an electrically insulating sheath of an electrical guide element, that is about a cable or a conductor bar, is arranged.
• OF INVENTION ⁇ dung is provided according to an Endenglimmschutz- on the coating, an electrically insulating heat conduction to ⁇ which has a thermal conductivity which min- At least this is the same as a thermal conductivity of the final corona protection coating itself.
• the invention is based on the recognition that a
• End corona protection is not heated equally at all points. Rather, with end corona shielding in the region of the transition between the end corona shielding and the adjacent external corona shielding, which is at ground potential, there is AC or DC current at a higher current than at that end of the end corona shield which faces the stripped end of the electrical conduction device. Accordingly, in particular the end of the
• a heat Trans ⁇ port is preferably effected to a major part with special, highly heat-conductive particles which are formed from an electrically insulating material whose thermal conductivity is greater than the thermal conductivity of the heat conducting layer within a total of the thermal conducting layer.
• particles are meant in particular bodies which have a diameter which is on average smaller than
• the overall proportion of the particles in the material of the thermal conductivity ⁇ layer is preferably above a percolation threshold of the particles.
• the particles are so close to each other that adjacent particles are also very likely to touch. Then, it is advantageously ensured that through the particles in the heat ⁇ leit slaughter continuous heat conduction paths are formed by the located above the heated area of the end corona protection point to cooler edge regions of the sauleit slaughter out.
• the particles are plate-shaped or disk-shaped.
• mica flakes or flakes of alumina may be used as particles.
• Platelets or discs have the advantage that their ratio of a diameter of the Schei ⁇ benform or even, in the case of a small plate, an edge length L, to a disc or plate thickness D can be much greater than one. This results in the advantage that even with a relatively small percentage by weight of the particles on the material of the heat conducting layer already the percolation threshold can be exceeded.
• the ratio of a largest diameter or a largest edge length L to the thickness is on average more than 50 (L / D> 50), in particular more than 80 (L / D> 80).
• the particles are aligned with respect to the flat Endenglimmschutz coating.
• the plate-TEN or disk-shaped particles with their defined by their shape plate or disk plane are aligned parallel composites f ⁇ che of Endenglimmschutz coating or at least form an angle with the surface of the is less than 30 °. Since this is the particles are very small objects that talk of an alignment can of course only in the statistical ⁇ 's sense be, that is not all particles may be oriented so but it is sufficient if most of the particles flat surface aligned the Endenglimmtikes.
• Particles with a particularly high thermal conductivity can be obtained if the particles are made of aluminum oxide (Al 2 O 3 ). Such particles are advantageously also very good electrical insulators. Preference is given to using particles which are each a monocrystal. Monocrystals generally have greater thermal conductivity than polycrystalline structures.
• the heat conducting layer comprises an electrically insulating, to a temperature of at least 140 ° C thermally stable material through which a matrix is formed, which the particles on the
• End corona protection coating keeps.
• a matrix can be applied together with the particles, for example in liquid form on the Endenglimmschutz and then cure.
• a polymer can be used as the material for the matrix.
• organic polymers ie z.
• a plastic or inorganic polymers, such as
• preceramic polymers in question.
• a ceramic can also be used as a substance for the matrix.
• Preceramic polymers and ceramics in this case have to be ⁇ sharmlichen advantage that they themselves have up to five times higher thermal conductivity than plastic. Even without the described particles, they can therefore already form a heat-conducting layer on their own, by means of which the invention is realized.
• a ceramic which can be used as a heat conducting layer or additionally as a matrix for the described particles can be, for example, based on
• the invention also includes such a high-voltage device with an end corona protection device according to one of the described embodiments.
• the inventive method relates to the production of a thermally conductive layer on an end corona protection, whereby then an embodiment of the invention
• End corona protection device can be produced.
• the method makes it possible initially to apply the heat-conducting layer in the form of a suspension, that is to say by spraying on, by dipping one provided with an end corona protection Cable in the suspension or z. B. also by brushing.
• a flowable mixture is provided, which serves as a matrix for arranging the thermally conductive particles on the
• This flowable mixture may be, for example, a polymer-hardener mixture or an inorganic polymer.
• the former may be, for example, an epoxy resin-hardener mixture, a mixture with rubber, polyestimate or a thermoplastic.
• ei ⁇ ne suspension of the particles and the substance mixture is produced.
• the particles used here are the particles already described, in particular aluminum oxide platelets.
• the particles preferably make up at least 40% by weight of the suspension (based on the solids content, ie without solvent).
• 70 wt .-% Al20 3 platelets are added.
• the suspension thus obtained is then applied in a further step of the process
• Endglimmtik applied where they can then harden and so creates a heat conducting layer of the heat-conducting particles and the matrix embedding them.
• the substance mixture or the suspension can be diluted to a predetermined flowability.
• a resin-hardener mixture to adjust the flowability ⁇ by means of methyl ethyl ketone and this with a DIN-Auslaufbecher with a 4 mm nozzle the flow time in a range of 12 to 18 seconds, preferably 15 seconds to set.
• the invention also encompasses further developments of the method according to the invention, which have features such as have already been described here in connection with the developments of the end corona shielding device according to the invention. For this reason, the corresponding training the inventive method be attributed ⁇ not be duplicated here.
• FIG. 2 shows a schematized electrical equivalent circuit diagram to the final corona protection device of FIG. 1,
• FIG 3 is an illustration of the cross section of Figure 1 with egg ⁇ nem diagram for a heat distribution
• FIG. 4 shows a schematic representation of a perspective view of the final corona protection device of FIG. 1 and FIG.
• FIG. 5 shows a schematic representation of a boundary layer between an end corona protection and a heat conducting layer of the end corona protection device of FI 1 in a perspective view.
• End corona shielding device can also be further developed other features described above.
• 1 shows an end corona protection device 10, in which a conductor bar 12 is surrounded by an electrical insulation 14. An internal potential control located between the insulation 14 and the conductor bar 12 is not shown in FIG.
• the conductor bar 12 protrudes from a Blechpa ⁇ ket 16 an electric machine, such as a Ge ⁇ generator, out.
• the conductor bar 12 may be formed, for example, of copper or aluminum.
• the electrical Isolie ⁇ tion 14 may be made from a polymer. In the area of
• Laminated core 16 is mounted on the electrical insulation 14 an outer corona protection AGS, which is electrically connected to a ground potential 18. Between the ground potential 18 and the conductor bar 12 is from a voltage source 20, z. B. the electric machine 16 (in the case that it is a generator), generates an AC electrical voltage that may have an effective value that is greater than 5 kV. At the end of the conductor bar 20, in the region of a transition point 22, the external corona protection AGS ends, while the insulation 14 continues in the direction of a bar end 24.
• a course of field lines 26 of the Lei ⁇ terstab 12 due to the voltage U outgoing electric field is influenced by a Endglimmschutz EGS.
• the final corona protection EGS has an electrical resistance which, at a field strength of the electric machine during operation End corona protection EGS penetrating field 26 is dependent on a location along the extension direction 30.
• Starting at the transition point 22 of the external corona protection AGS for end corona protection EGS is a relatively low surface resistance of the
• the end corona protection EGS has an electrical resistance which is one or more orders of magnitude greater than its resistance at the transition point 22. This will be in the environment of the final corona protection EGS, the electric field strength of the field lines 26 or the electrical potential distribution, illustrated in FIG. 1 by potential lines 32, are distorted in such a way that they impinge on an outer surface of the
• End glow protection EGS gives the potential distribution 28.
• the electric potential increases in this case, starting from the transition point 22 About ⁇ steadily and reached 34 at a distance from the transition point 22 which may be, for example, 20 cm, at the end 24 toward the maximum voltage value of
• End corona shield 10 is shown.
• the result is the largest current density I, which represents the sum of all currents induced in Endenglimmschutz EGS. Due to the high current density I results in accordance with a caused by this capacitive current Joule 'see power loss in Endglimmstoff, which has a maximum at the transition point 22, resulting in a formation of a hot spot (hotspot) in the transition area 22 of the final corona protection EGS forêtglimmschutz AGS could lead.
• I represents the sum of all currents induced in Endenglimmschutz EGS. Due to the high current density I results in accordance with a caused by this capacitive current Joule 'see power loss in Endglimmschutz, which has a maximum at the transition point 22, resulting in a formation of a hot spot (hotspot) in the transition area 22 of the final corona protection EGS forêtglimmschutz AGS could lead.
• FIG. 3 for this purpose, a possible, resulting temperature profile 36 of a temperature T in the external corona protection AGS and End corona protection EGS shown.
• the temperature profile 36 shows that a hot zone 38 can form in the region of the transition point 22.
• high voltage generators and other electrical high voltage equipment temperatures can be reached at such a hot spot, up to or even above the maximum for the material of
• the Endenglimmschutz EGS the Endenglimmschutzvorraum 10 has a temperature distribution 40, which has a lower maximum temperature in the area of zone 38 as the temperature curve 36. This is effected by a thermal conductivity ⁇ layer 42, in the manufacture of
• End corona protection device 10 or subsequently applied to the end corona protection EGS.
• the Endenglimmschutzan extract 10 is shown once again in perspective.
• the temperature distribution 40 is 4 by isotherm (dashed lines) indicated in FIG as well as by temperature ⁇ turan gave Tl, T2, T3, T4, T5 for individual points of the heat ⁇ conductive layer 42 along the extending direction 30th
• the heat-conducting layer 42 may also extend beyond the transition point 22 to the outer corona protection AGS.
• the heat conducting layer 42 may consist of a lacquer which is electrically insulating and thermally highly conductive.
• the lacquer may consist of a matrix, preferably of a thermally stable plastic (preferably heat class H) or an inorganic matrix, preferably polysiloxane, polysilazane or
• Polycarbosilane exist. This matrix is filled with an electrically insulating material, which causes the heat transfer within the heat conducting layer 42 mainly.
• the material consists of platy, mo ⁇ nokristallinem alumina.
• These particles are so numerous ⁇ rich in the thermal layer 42 include, exceeded that Perkolati- onsschwelle and thus closed by the particles heat paths from the heat zone 38 and out are formed in the thermal conducting ⁇ nergur 42nd Due to the high thermal conductivity at the surface of the Endenglimmschutzes EGS due to the Vintageleit Mrs 42, the heat from the hot zone 38 is distributed over a larger area and thus better dissipated to the ambient air.
• Ver ⁇ is equal to the heat distribution 36, the hot-spot temperature is so significantly reduced by the improved cooling (see heat distribution 40).
• One way to produce the heat conducting layer 42 be ⁇ therein is to mix an epoxidic resin-hardener-mixture is from 70 wt .-% AL20 3 flakes.
• a flow time on a DIN-Auslaufbecher with 4 mm nozzle by adding
• Methyl ethyl ketone can be adjusted to about 15 s. Subsequently ⁇ td the suspension is the transition point 22 at their appli- for example, by spraying onto the Endenglimmschutz and EGS.
• FIG 5 is a greatly enlarged in relation to the other figures representation of an interface between the
• particles 46 are held.
• the particles are plate shaped and have an edge length L, which, on average, between 10 and 100 ym, preferably 40 ym, be transmits ⁇ .
• a slice thickness D is smaller by a factor 80 to 120 than the edge length L, so that a ratio L / D results, which is preferably 100 on average.
• Parti ⁇ cle 46 are with respect to a surface 48 of the
• a normal vector 50 of the plane of extent of a plate shape of a particle 46 with the normal vector 52 of the surface 48 of the end corona shield EGS encloses an angle W which is in the range of zero to 45 °, preferably 0 ° to 30 °.
• the plates are thus aligned with one of their flat sides to the surface 48 and can thus absorb heat particularly well from the final corona protection EGS.
• the concentration of the particles 46 in the matrix 44 is above the percolation threshold. Adjacent particles 46 are therefore likely to touch each other.
• End corona protection EGS in the form of rapid heat dissipation in cooler areas, such as the external corona protection AGS and towards the end 24, cooled.
• cooler areas such as the external corona protection AGS and towards the end 24, cooled.
• the thermal load is one
• End corona protection in the hot spots is the decisive factor in the case of degradation of the end corona protection, ie, in the case of embrittlement.
• By reducing the temperature in the hot spots of the end corona shielding can have a longer lifetime than he ⁇ the end corona shielding be ensured and can be a Endenglimmschutz withstand higher test voltages. The latter is required for new generators.
• With such audit results namely the highest thermal DEMANDS ⁇ Chung when the voltage U is, for example, to a value set during the first high-voltage test, which is significantly greater than the rated voltage Un.
• such a stress test can be done by applying a voltage for one minute

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• Organic Insulating Materials (AREA)
• Processing Of Terminals (AREA)

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• 2012
  • 2012-03-29 DE DE102012205048A patent/DE102012205048A1/de not_active Ceased
• 2013
  • 2013-03-26 WO PCT/EP2013/056386 patent/WO2013144135A2/fr not_active Ceased

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