EP1676352A1 - Procede de reparation des enroulements statorique refroidis par eau dans de generateurs - Google Patents

Procede de reparation des enroulements statorique refroidis par eau dans de generateurs

Info

Publication number
EP1676352A1
EP1676352A1 EP04791208A EP04791208A EP1676352A1 EP 1676352 A1 EP1676352 A1 EP 1676352A1 EP 04791208 A EP04791208 A EP 04791208A EP 04791208 A EP04791208 A EP 04791208A EP 1676352 A1 EP1676352 A1 EP 1676352A1
Authority
EP
European Patent Office
Prior art keywords
water box
water
front cover
conductors
filler metal
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.)
Withdrawn
Application number
EP04791208A
Other languages
German (de)
English (en)
Inventor
Hubert Lotz
Xavier Mougin
Christian Petrement
David Poirson
Eric Veith
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Technology GmbH
Original Assignee
Alstom Technology AG
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 Alstom Technology AG filed Critical Alstom Technology AG
Priority to EP04791208A priority Critical patent/EP1676352A1/fr
Publication of EP1676352A1 publication Critical patent/EP1676352A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K1/00—Soldering, e.g. brazing, or unsoldering
    • B23K1/0008—Soldering, e.g. brazing, or unsoldering specially adapted for particular articles or work
    • B23K1/0016—Brazing of electronic components
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K15/00—Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines
    • H02K15/0056—Manufacturing winding connections
    • H02K15/0068—Connecting winding sections; Forming leads; Connecting leads to terminals
    • H02K15/0081—Connecting winding sections; Forming leads; Connecting leads to terminals for form-wound windings
    • H02K15/0093—Manufacturing or repairing cooling fluid boxes, i.e. terminals of fluid cooled windings ensuring both electrical and fluid connection
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/72—Wind turbines with rotation axis in wind direction

Definitions

  • This invention relates to a method of repairing the stator bars constituting water- cooled stator windings in generators and a water-cooled stator bar for a generator, comprising at each end thereof a water box.
  • Large generator stator bars typically comprise a plurality of small solid and hollow conductors, usually of copper, brazed together and brazed into a water box at each end whereby cooling water may be circulated through the hollow conductors.
  • An important maintenance concern with this type of water-cooled stator bars is the risk of water leakage from the water boxes to the stator bar insulation. Leakage can arise as a result of: poor quality of the original brazing during manufacture of the bar; corrosion processes in the water box; or mechanical fatigue. If leakage occurs, the presence of water in the stator bar insulation will eventually result in electrical failure of the generator.
  • a method of re-sealing the joints between the individual conductors and the water box includes sealing the stator bar end connections from within the stator bar end fitting.
  • a low viscosity epoxy is initially applied from within the chamber of the end fitting by use of a horoscope and a syringe-type applicator, the low viscosity epoxy being applied to all joints between the adjacent strands of the stator bar and between the fitting and the outermost strands of the stator bar.
  • a high viscosity epoxy is then applied over the low viscosity epoxy using the boroscope and applicator. The epoxy is then cured.
  • This method has several drawbacks.
  • US-A-5809632 discloses a repair method in which the water box is first cut open and then the joints between the conductors are soldered using a TIG torch or other heating device. The cover to the water box is then welded back in place. Due to the enormous heat peaks caused by the welding operation, the stator bar is permanently cooled during the imperviousness resumption and requires specific cover fixed during operations at the back of the water box. Additionally, this method has a further major drawback since only the oxide film at the surface extremities of the conductors in the water box is removed but no major cleaning is conducted before soldering the conductors. This will induce a risk of deterioration of the coating metallic properties due to thermal damage of the remaining pollution agents behind strands surface. In addition, in this method as a major drawback in terms of associated risk to the methodology the second stator bar electrically linked to the repaired one has its water box as well cut and a new front cover welded with the electrical link between bars modified from the original design.
  • US 5,659,944 discloses a method of repairing a joint between conductor elements of a stator winding bar of an electrical machine and a connecting device connected to an end of the stator winding bar for providing electrical connection and coolant flow for the conductor elements.
  • This method includes the steps of removing an existing connection device from the end of the stator winding bar, aligning the conductors of the end of the stator winding bar by heating the bar end to above the flow point of the braze holding the conductors in position while simultaneously holding the conductors of the end of the stator winding bar under compression in two orthogonal directions perpendicular to the length of the stator winding bar; forming slots in the end of the stator winding bar and at locations such that the slots extend to locations where the conductor elements abut one another; applying an electrically conductive first connecting part onto the end of the stator winding bar such that the first connecting part substantially surrounds the end of the stator winding bar and sealing the gaps and slots.
  • the original connecting device is completely removed and replaced by a new connecting device.
  • the heating above the flow point of the braze involves the risk to damage the insulation behind the connecting device.
  • the above method involves milling introducing narrow slots in the transverse and vertical direction between adjacent conductor elements. This involves the use of a milling machine that requires tight machining accuracy.
  • the technical problem to be solved by the present invention is to provide a method of repairing generator stator windings which will improve the reliability and service life of the repaired components and which avoids the drawbacks of the cited prior art. Further, the invention should provide a repair method for in situ repair to avoid costs caused by disassembling the whole generator. Furthermore, a fluid-cooled stator bar for a generator, comprising at each end thereof a water box with extended life cycle should be provided.
  • the present invention provides a method of repairing generator stator windings which improves the reliability and service life of the repaired components and which avoids the drawbacks of the cited prior art.
  • the repair method according to the present invention provides for an in situ repair and avoids costs caused by disassembling the whole generator.
  • the inventive method can also be applied before leakage or other damages occur and thus serves as damage prevention as well.
  • the method of repairing fluid-cooled stator windings in generators comprises: opening the water box; grinding the entire exposed copper conductor surface of the opened water box by cutting a single part water box or by removing the front cover from a multi part water box; grinding and/or cleaning the entire exposed copper conductor surface of the opened water box; applying over the back end of the exposed interior surface of the opened water box a coating of a filler metal; closing the water box by means of brazing of a front cover of the original geometry. Due to the prior grinding and/or cleaning of the entire exposed surface, all oxide film deposits on the surface of the conductors elements are removed.
  • the cleaning of the exposed surface can be conducted by using stainless steel brushes and/or by using hand milling equipment, for instance with spherical head grinders. If needed, also cleaning agents can be used.
  • the original front cover may be re-used or a new cover might be applied.
  • the brazing of the front cover is generally performed at a low temperature, at maximum to the flow point of the braze but well below 780°C.
  • An advantageous embodiment of the invention is characterised in that after removing the oxide film from the conductors, coolers are installed around the body of the water box, with fibreglass tape around the conductors at the rear of the box. This is especially advantageous with multi part water boxes.
  • Another advantageous embodiment of the invention is characterised in that during the step of opening the water box the original connecting device remains maintained. This allows re-using the original parts.
  • Another advantageous embodiment of the invention is characterised in that for the step of closing the water box the original front cover and the original connecting device are re-used.
  • the filler metal is a copper alloy, more preferably containing silver and phosphorus.
  • An especially preferred alloy comprises 15% silver, 80% copper and 5% phosphorus.
  • no flux is used. Usage of the described material has been proven to not cause any chemical interaction with pre-existing materials in the generator and therefore no unexpected damages caused by chemical interactions are caused.
  • the filler metal is preferably applied by the use of a TIG torch.
  • a preferred TIG unit includes a double flux torch (for example the TIG FORCE system from the AIR LIQUIDE welding group) using a mixture of Argon and Helium, preferably 80% Argon and 20% Helium. It has been found that the use of the double flux torch combined with the preferred gas mixture ensures very low heat diffusion during the application of the filler metal, thereby not jeopardising the integrity of the stator bar wall insulation. This has the advantage that during the repair process no specifically designed additional cooling system has to be installed to avoid overheating of the stator bar insulation.
  • the method of the invention comprises, before application of the filler metal, the step of machining the conductor ends until they are substantially flush with the inner surface. This ensures accurate cleaning and will avoid risk of copper conductor melting during the repair process. In addition, in case of hollow conductors clogging (usually, a clogging phenomenon will produce accumulation of oxides at the outlet section of the conductors), the method will ensure to recover the original individual strand flow rate.
  • the method of the present invention allows repairs to be carried out on the stator bar without requiring its removal from the generator, and enables the working life of the component to be substantially extended.
  • a fluid-cooled stator bar for a generator comprising at each end thereof a water box, is characterised in that at least one water box has a coating of filler metal over the back end of the internal surface thereof.
  • a preferred embodiment provides that the coating extends over the whole of the back end of the internal surface.
  • Figure 1 is a sectional view through one end of one type of stator bar with the end of the water chamber removed;
  • Figure 2 is a corresponding view showing the bar after machining of conductor ends
  • Figure 3 illustrates the result of the brazing coating stage
  • Figures 4, 5 and 6 are respectively top plan, side elevation and end views of another type of stator bar to which the method of the invention can be applied.
  • a generator stator bar comprises a plurality of solid copper conductors 1 and hollow copper conductors 2 brazed together and sealed into a water box 3 by brazing.
  • the water box 3 comprises a front part or front cover 5 and a rear part or connecting device 7.
  • the water box 3 has a water inlet or exit pipe 4 there through, of which only a short section is shown in the Figure.
  • the first step of the repair method is to cut through the box 3 to remove the front part 5 thereof, including the pipe 4. This is preferably done using a locating jig.
  • Figure 1 shows the bar end at the completion of this stage. Scavenging nitrogen flow is then installed at the opposite end of the bar.
  • the next step in the method is to grind the ends of the solid and hollow conductors 1 and 2 until they are levelled with the internal surface of the water box 3, as shown in Figure 2. Further, this also provides the removal of the oxide film and deep cleaning to eliminate under surface corrosion. This step is suitably carried out using a hand-milling tool equipped with a spherical head.
  • glass fibre tape is wrapped around the rear part of the box and the un-insulated part of the bar projecting therefrom.
  • the water box is then pre-heated by a 50 kW high-frequency induction heater to a temperature of 250 to 300 degrees C in readiness for the TIG brazing operation.
  • the TIG brazing operation is carried out while controlling the temperature of the copper conductors at the rear part 7 of the water box 3 to keep it below 180° C.
  • the operation comprises: installing reverse nitrogen scavenging flow in the bar at 5 litres per minute; performing a first operation to melt the conductors on the green bar outer surface next to the box 3 and between each conductor; performing a second similar operation using filler metal 0.5 B1 (NFA 81362) (15% silver, 80% copper, 5% phosphorus); and performing a third operation without filler metal to smooth the surface and eliminate possible cracks.
  • Figure 3 shows the water box with an internal coating 6 of the filler material, resulting from these operations.
  • a pressure test is carried out to ensure water-tightness by means of installation of a temporary cover.
  • the front part 5 of the water box and its mating surface are then prepared for reattachment by manually machining surfaces to ensure that any clearance between them is less then 0.1 millimetres and the roughness is less than 1.6.
  • the front part 5, to which the electrical connection and the water connection are already attached, is attached to the box 3 by brazing, using high- frequency induction brazing equipment and a 0.4 millimetres shim of the same filler metal as is used for the internal coating process and with a nitrogen scavenging flow rate set at 10 litres per minute.
  • the heating is performed by means of a single closed loop inductor with concentrators. Each is required to hold the front part five in position and at a constant pressure on the brazed joint during the operation.
  • the temperature is regulated to 720° C maximum, with a thermocouple installed at 3 millimetres from the joint of the cover.
  • the original front part can be reinstalled only if the bar to bar electrical connection was originally brazed with a filler metal whose melting point is lower than that of the 0.5 B1 metal. If this is not the case, the original electrical connections must first be milled away and new ones raised on using GB 50 (50% silver, 50% copper) filler metal. The pressure-tightness of the bar is then tested by way of a pressure or helium test.
  • the invention has been particularly described with reference to a conventional type of water box arrangement for a stator bar.
  • a similar process may be used for other types of stator bar water box, for example the type having a removable front cover, as illustrated in Figures 4 to 6.
  • the solid conductors 41 terminate at and are brazed in the rear end 42 of the clip, while the hollow conductors 43 continue forward to the front end 44 of the clip, where they are arranged in an array and are brazed in position.
  • a front cover 45 is bolted and soft brazed on to the clip over the open ends of the hollow conductors 43 to constitute the water box.
  • the front cover 45 is provided with a hydraulic connection 46 for connection of the cooling water supply.
  • the cover is unbolted and heated by mans of an induction heater to release the soft brazing.
  • the hollow conductor ends thus exposed are cleaned and have their oxide film removed by means of a stainless steel brush and other deep cleaning means and agents if necessary, and coolers are then installed around the body of the water box, with fibre glass tape around the conductors at the rear of the box.
  • the TIG brazing and testing steps are then carried out in the same way as for the conventional water box described with reference to Figures 1 to 3.
  • the joint surface for receiving the cover 45 is then milled using a specific jig calibrated to the shape of the water box face, before reinstallation of the cover in accordance with the original bar manufacturing process.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Power Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Manufacture Of Motors, Generators (AREA)
  • Windings For Motors And Generators (AREA)

Abstract

Selon l'invention, on prévoit un procédé de réparation d'enroulements de stator refroidis à l'eau dans des génératrices, les enroulements comprenant des barres de stator comprenant des conducteurs creux (2) placés hermétiques dans une boîte d'eau respective (3) à chaque extrémité, la boîte d'eau étant un élément à partie simple ou un élément à multiples parties, comprenant un dispositif de connexion (7) et un couvercle avant. Le procédé consiste à ouvrir la boîte d'eau par la découpe de la boîte d'eau à partie simple ou par le retrait du couvercle avant d'une boîte d'eau à multiples parties; à broyer et/ou nettoyer la surface du conducteur de cuivre totalement exposée de la boîte d'eau ouverte; à appliquer sur l'extrémité arrière de la surface interne exposée de la boîte d'eau ouverte un revêtement (6) d'un métal de charge; et à fermer la boîte d'eau au moyen du brasage du couvercle avant à géométrie originale.
EP04791208A 2003-10-13 2004-10-12 Procede de reparation des enroulements statorique refroidis par eau dans de generateurs Withdrawn EP1676352A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP04791208A EP1676352A1 (fr) 2003-10-13 2004-10-12 Procede de reparation des enroulements statorique refroidis par eau dans de generateurs

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP03103782A EP1524754A1 (fr) 2003-10-13 2003-10-13 Procédé de réparation des enroulements statorique refroidis par eau dans de générateurs
EP04791208A EP1676352A1 (fr) 2003-10-13 2004-10-12 Procede de reparation des enroulements statorique refroidis par eau dans de generateurs
PCT/EP2004/052516 WO2005039021A1 (fr) 2003-10-13 2004-10-12 Procede de reparation d'enroulements de stator refroidis a l'eau dans des generatrices

Publications (1)

Publication Number Publication Date
EP1676352A1 true EP1676352A1 (fr) 2006-07-05

Family

ID=34354588

Family Applications (2)

Application Number Title Priority Date Filing Date
EP03103782A Withdrawn EP1524754A1 (fr) 2003-10-13 2003-10-13 Procédé de réparation des enroulements statorique refroidis par eau dans de générateurs
EP04791208A Withdrawn EP1676352A1 (fr) 2003-10-13 2004-10-12 Procede de reparation des enroulements statorique refroidis par eau dans de generateurs

Family Applications Before (1)

Application Number Title Priority Date Filing Date
EP03103782A Withdrawn EP1524754A1 (fr) 2003-10-13 2003-10-13 Procédé de réparation des enroulements statorique refroidis par eau dans de générateurs

Country Status (2)

Country Link
EP (2) EP1524754A1 (fr)
WO (1) WO2005039021A1 (fr)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7276134B2 (en) * 2004-10-18 2007-10-02 General Electric Company Methods and systems for sealing liquid cooled stator bar end connections for a generator
JP2013165585A (ja) * 2012-02-10 2013-08-22 Toshiba Corp 固定子コイル接続装置および回転電機
EP2950424B1 (fr) * 2014-05-26 2020-11-04 General Electric Technology GmbH Chambre pour conducteurs de machines électriques
DE102018202601A1 (de) * 2018-02-21 2019-08-22 Siemens Aktiengesellschaft Verfahren zur Reparatur von Lötstellenleckagen
CN111934500B (zh) * 2020-06-29 2021-10-15 东方电气集团东方电机有限公司 一种发电机定子测温元件的更换方法
CN112454138B (zh) * 2020-11-23 2022-10-21 句容市双利金属制品有限公司 一种风力发电机定子扇形片加工用去毛刺装置及其使用方法

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE526043A (fr) * 1953-01-27
US5659944A (en) * 1995-01-26 1997-08-26 Asea Brown Boveri Ag Method for repairing a connecting device for the electrical connection and for supplying and carrying away the coolant to and from the hollow conductor elements of the stator winding bars of electrical machines
FR2736769B1 (fr) * 1995-07-13 1997-10-10 Jeumont Ind Procede de reparation d'une boite a fluide de refroidissement d'une barre statorique d'un alternateur electrique
FR2747064B1 (fr) * 1996-04-03 1998-05-15 Air Liquide Procede et dispositif de reduction des emissions d'ozone produites lors d'une operation de soudage a l'arc sous gaz de protection
US5875539A (en) * 1996-11-14 1999-03-02 Siemens Westinghouse Power Corporation Water-cooled stator coil end sealing process
US6577038B2 (en) * 2000-12-26 2003-06-10 General Electric Company Stator bar header with hollow strand package

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2005039021A1 *

Also Published As

Publication number Publication date
WO2005039021A1 (fr) 2005-04-28
EP1524754A1 (fr) 2005-04-20

Similar Documents

Publication Publication Date Title
US7617603B2 (en) Method for inspection and repair
US6491208B2 (en) Cold spray repair process
US5796189A (en) Brazing procedure for generator liquid cooled stator bars
CA2798489C (fr) Moyens et methode de reparation de tube chauffant de generateur de vapeur
JP2836969B2 (ja) 二片型電気および流体コネクタとその設置方法
JPH08237896A (ja) 電気機械のステータコイルロッドの中空の導体エレメントへの冷却液の給排のため及び電流接続のために働く接続装置を修復する方法
US6247231B1 (en) Method for repairing heat exchanger tubing through partial tube replacement
US5659944A (en) Method for repairing a connecting device for the electrical connection and for supplying and carrying away the coolant to and from the hollow conductor elements of the stator winding bars of electrical machines
US6784573B1 (en) Corrosion-resistant liquid-cooled armature bar clip-to-strand connection and related method
KR20000053286A (ko) 수냉식 고정자 코일 끝부 밀봉방법
US5205038A (en) Method of replacing a tube on a straight-tube heat exchanger
US5809632A (en) Method for repairing a cooling fluid box of an electric alternator stator bar
EP1524754A1 (fr) Procédé de réparation des enroulements statorique refroidis par eau dans de générateurs
EP2577208B1 (fr) Dispositif de préchauffage d'air de gaz de carneau, et procédé pour son installation, ainsi qu'un composant de conduite d'air pour un dispositif de chauffage d'air de gaz de carneau
US7088020B2 (en) Apparatus and method for consolidating conductive strands of a stator coil
EP0047410B1 (fr) Procédé pour le brasage fort de douilles
KR101937610B1 (ko) 원자로 배관의 노즐 정비방법
US5560841A (en) Stator vane extraction
KR930011021B1 (ko) 세라믹 용제밴드를 가지는 경납땜용 슬리이브와 그 제조 방법
KR102021245B1 (ko) 노즐 정비방법
US6596957B2 (en) Method and apparatus and prefabricated replacement tube for localized waterwall repair
JPH0360583B2 (fr)
JP2003071560A (ja) タービン翼のステライト鑞付装置
US20210044183A1 (en) Method for repairing solder joint leakages
CN114211120B (zh) 一种用于压水堆核电站的蒸汽发生器管子-管板接头

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20060428

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): FR

DAX Request for extension of the european patent (deleted)
RBV Designated contracting states (corrected)

Designated state(s): FR

17Q First examination report despatched

Effective date: 20090610

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20110503