EP0246430A1 - Transformer core support - Google Patents

Transformer core support Download PDF

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Publication number
EP0246430A1
EP0246430A1 EP87104861A EP87104861A EP0246430A1 EP 0246430 A1 EP0246430 A1 EP 0246430A1 EP 87104861 A EP87104861 A EP 87104861A EP 87104861 A EP87104861 A EP 87104861A EP 0246430 A1 EP0246430 A1 EP 0246430A1
Authority
EP
European Patent Office
Prior art keywords
transformer
clamping
tensioning
bridging
coupled
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Withdrawn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
EP87104861A
Other languages
German (de)
English (en)
French (fr)
Inventor
Thomas Edwin Van Schaick
Morris Vernon Van Dusen
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 Co
Original Assignee
General Electric Co
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 General Electric Co filed Critical General Electric Co
Publication of EP0246430A1 publication Critical patent/EP0246430A1/en
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F3/00—Cores, Yokes, or armatures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/24—Magnetic cores
    • H01F27/26—Fastening parts of the core together; Fastening or mounting the core on casing or support
    • H01F27/263—Fastening parts of the core together

Definitions

  • This invention relates to support apparatus for the core of a transformer and, more particularly, to support apparatus for securing laminations of the core against loosening or vibrating, especially in the window area of the core.
  • the core is fabricated from a plurality of laminations which are appropriately shaped, registered and stacked to form the core.
  • the core generally includes three parallel spaced apart legs having respective ends thereof connected by respective yokes.
  • the space between adjacent legs and bounded in part by the yokes is known as a window.
  • at least two windings which may be concentric with respect to each other, circumferentially surround each leg, are in magnetic flux communication therewith and pass through at least one window.
  • mutual magnetic flux is conducted between adjacent legs through portions of the yokes around the window between them.
  • a requirement of such transformers is that during operation sufficient clamping load be maintained on the core laminations to prevent them from loosening and/or vibrating due to magnetic forces, which result from eddy currents induced in the laminations during operation of the transformer.
  • a particularly difficult area in which to maintain adequate clamping load is at the portion of the transformer window which is bounded by a yoke, since mutual flux of the transformer, i.e.
  • a previous core clamping method used metallic threaded bolts which pass through a hole in the core laminations.
  • bolt holes through core members contribute to undesirable stresses and flux concentrations.
  • One method for eliminating holes through the core involves using metallic yoke clamping channels, disposed on opposite sides of the yoke of the transformer, with metallic studs disposed around the outer periphery of the yokes and no direct clamping, such as metallic studs, in the window area.
  • this method relies on clamping loads supplied by the clamping channels for supplying compressive loading in the window area. These clamping loads tend to decrease as the distance from a stud increases.
  • This approach results in significant variation in compressive loads applied to core laminations with potential reduction in overall quality and operating efficiency of the transformer. It is desirable that surface stresses in laminations be minimized by using clamping methods which evenly distribute stresses.
  • non-metallic washers may be compromised by physical degradation, such as cracking, and/or by contamination, which may establish or faciliate formation of an electrical conductive path over the surface of the washer, wherein the path extends the relatively short distance from the metallic stud at the center of the washer to the channel at the outer periphery of the washer.
  • Another object of the present invention is to increase the electrical insulative path length of the clamping device over previously known devices.
  • Still another object is to remove electrically conductive objects from the vicinity of high voltage between the coils of a transformer.
  • an electric transformer comprises a pair of legs each having a first and second end respectively connected by a first and second yoke, respectively, clamping means for straddling the first yoke and tensioning means coupled to the clamping means for urging the clamping means into compressive engagement with the first yoke, wherein the tensioning means include electrically insulative bridging means having a first and second end respectively coupled to the clamping means, such that the clamping means compressively engages the first yoke when the tensioning means is subjected to a predetermined amount of tension.
  • tensioning means for compressing the laminations comprises clamping means for straddling the core and bridging means for urging the clamping means into compressive engagement with the core when the bridging means is subjected to a predetermined amount of tension, wherein the bridging means includes an electrically insulative material, such as a polyamide.
  • Transformer 10 comprises a core 22 and coils 31, 33 and 35.
  • Core 22 includes three substantially parallel spaced apart legs 21, 23 and 25 and a pair of substantially parallel yokes 24 and 26 connected to respective ends of legs 21, 23 and 25.
  • Yoke 24 magnetically couples one end of each leg 21, 23 and 25 and yoke 26 magnetically couples the other end of each leg 21, 23 and 25.
  • Legs 21, 23 and 25 and yokes 24 and 26 are typically fabricated from a plurality of laminations 20 which are appropriately shaped, registered and stacked as is known in the art.
  • Pairs of clamping channels 12 and 14 typically respectively comprise an electrically conductive material like a metal, such as iron or steel.
  • a window 16 is defined by spaced apart legs 21 and 23 and the portion of spaced apart yokes 24 and 26 therebetween.
  • a window 18 is defined by spaced apart legs 23 and 25 and the portion of spaced apart yokes 24 and 26 therebetween.
  • Coils 31, 33 and 35 corresponding to a respective phase of the transformer, respectively circumferentially surround legs 21, 23 and 25.
  • Coils 31, 33, and 35 generally each include at least two windings which may be conventionally designated as primary and secondary.
  • a pair of coolant fluid inputs 11 and a pair of coolant fluid outputs 13 permit respective introduction and removal of coolant fluid, which is disposed in heat flow communication with core 22 for cooling core 22, if desired.
  • a plurality of blocks or flanges 28 are disposed at predetermined locations along the outer periphery of channel 15 and 19.
  • Blocks 28 may be integral channel 15 and 19 or rigidly affixed thereto, such as by welding.
  • a corresponding plurality of blocks or flanges (not shown) is predeterminedly disposed along the outer periphery of the other channel of pair of channels 12 and 14.
  • Blocks 28 that are coupled to channels 15 and 19 and the corresponding blocks (not shown) coupled to the other member of pair of channels 12 and 14 each include a hole for receiving conventional tightening means, such as a metallic rod that is threaded at both ends to extend through the hole of block 28 and the hole of the corresponding block of the other member of pair of channels 12 and 14.
  • the metallic rod is secured by a nut which engages block 28 and the corresponding blocks to forceably compress the respective outer portion of pair of channels 12 and 14 together, thereby respectively compressively sealing the laminations of yoke 24 and 26 therebetween.
  • holes 29 may be provided through channels 19 and 15 and the other channel of pair of channels 12 and 14 toward the inner side of the channel, outside legs 21 and 25 and near the end of each of the pair of channels 12 and 14 at respective ends thereof for receiving conventional tightening means, such as was described as being disposed in cooperation with blocks 28.
  • a block 28 could be secured to respective ends of pair of channels 12 and 14 for clamping the ends of pair of channels 12 and 14 using conventional tightening means.
  • respective tensioning means 40 are coupled to pair of channels 12 and 14 in windows 16 and 18.
  • tensioning means 40 which include an electrically insulative material, as explained in detail below, be appropriately disposed in windows 16 and 18.
  • tensioning means 40 in accordance with the present invention, be used at predetermined locations along the periphery of channel pairs 12 and 14 for maintaining adequate clamping forces on laminations 20 of core 22.
  • Restraining means 27, such as a block or flange, for fixedly securing tensioning means 40, are coupled to channel 15 and 19, or fabricated integral therewith, in the area of windows 16 and 18. Corresponding restraining means 27 are appropriately coupled to the other channels (not shown in Fig. 1) of pair of channels 12 and 14. Although restraining means 27 may be fixedly coupled to channel 15 and 19 respectively, such as by welding, or be integral therewith, it is preferable that at least one cooperating pair of restraining means 27 disposed in each of window 16 and 18, respectively, be removably coupled to pair of channels 12 and/or 14 in order to permit installation, removal and replacement of coil 31, 33 and/or 35 without disassembly of pair of clamping channels 12 and/or 14.
  • FIG. 2 a view looking in the direction of the arrows of line 2-2 of Fig. 1, with coils 31 and 33 removed for ease of illustration, is shown, but not necessarily to scale.
  • a channel 17, the other member of pair of channels 14, is shown compressively engaging laminations 20 of yoke 26 and leg 21 of core 22.
  • a similar channel (not shown) that is appropriately disposed with respect to core 22 and yoke 24 forms the other channel of pair of channels 12.
  • Tensioning means or clamping device 40 comprises bridging means 37 and retaining means 30. Retaining means 30 and bridging means 37 are shown extending between respective restraining means 27, which are shown removably coupled to channel 15 and 17.
  • Retaining means 30 comprises a shank 32 having a cross member 34 fixedly secured to one end thereof and the other end thereof threaded for receiving a nut 36.
  • Shank 32, cross member 34 and nut 36 may each be metallic.
  • shank 32 may have an eye loop fixedly secured to the non-threaded end thereof.
  • retaining means 30 may be described as a T-bolt and eye-loop bolt, respectively.
  • Restraining means 27 include a hole therethrough for receiving the threaded portion of shank 32 of retaining means 30.
  • Restraining means 27 may be metallic and are removably secured to channel 15 and 17 of pair of channels 14 by fastening means 38.
  • Fastening means 38 include an externally threaded member 44, which is fixedly coupled to restraining means 27 and extends through a hole 41 of channel 15, and a nut 39 for threadably engaging member 44 and abuttingly engaging channel 15 for removably securing restraining means 27 to channel 15.
  • a recess or counter bore 43 may be provided in channel 15 for receiving nut 39 and preventing undesirable loosening thereof.
  • Fastening means 38 is similarly secured to restraining means 27 and channel 17.
  • Bridging means 37 extends between channels 15 and 17 and is coupled at respective first and second ends thereof to retaining means 30 proximate channel 15 and retaining means 30 proximate channel 17.
  • Bridging means 37 comprises arms 46 and 48 formed from a material which is electrically insulative, has high tensile strength, typically at least about 90,000 psi and preferably greater than that of restraining means 27 and retaining means 30, and good dimensional stability, that is, nearly zero elongation under tension. In other words, the material comprising bridging means 37 tends to rupture without elongating when subjected to a predetermined amount of tension.
  • a material meeting these requirements for bridging means 37 is an aromatic polyamide.
  • a preferred aromatic polyamide is poly (phenylenephthalamide), one example of which consists essentially of securing units of poly (1, 4-phenyleneterephthalamide), described as Kevlar by Gan et al, in Vol. 19 of the Journal Of Applied Polymer Science , pp. 69-82 (1975).
  • poly phenylenephthalamide
  • Kevlar by Gan et al, in Vol. 19 of the Journal Of Applied Polymer Science , pp. 69-82 (1975).
  • other synthetic or naturally occurring materials meeting the above requirements may be used.
  • Bridging means 37 may include a relatively thick strand of material, having a predetermined tensile strength, disposed in a single pass between respective restraining means 27 to form arms 46 and 48 and having the ends threof secured at a tie point 45, such as by fusing.
  • bridging means 37 may include a plurality of strands of electrically insulative material each disposed in a single pass between respective restraining means 27.
  • it is preferable that bridging means 37 include a relatively thin strand of material, having a predetermined tensile strength, interlaced in a plurality of passes and in a predetermined pattern between respective restraining means 27 so that arms 46 and 48 respectively include a plurality of segments of the strand of material.
  • arms 46 and 48 of bridging means 37 include a plurality of strand segments
  • the plurality of strand segments may be impregnated with a curable solventless polyester resin, for tieing the strand segments together to prevent fretting or chafing and for augmenting the tensile strength of the plurality of strand segments.
  • nuts 36 may be tightened to apply tension to tensioning means 40 which in turn applies tension to restraining means 27 and fastening means 38 for urging channels 15 and 17 together and thereby compressively engaging laminations 20 of yoke 26.
  • the magnitude of the compressive force with which channels 15 and 17 engage core 22 may be appropriately adjusted by the degree of tightening of nuts 36.
  • Bridging means 37 also electrically insulates restraining means 27 and retaining means 30 which are coupled to channel 15 from retaining means 27 and retaining means 30 which are coupled to channel 17, thereby preventing entirely surrounding mutual flux path 47 (Fig. 1) with an electrically conductive material.
  • Shank 32 of retaining means 30 may be made very short so as substantially to remove or minimize metallic structure between coils 31 and 33 (Fig. 1) of transformer 10, while also increasing the electrical insulative path length over prior devices.
  • Arms 46 and 48 of bridging means 37 are shown to include a plurality of segments of a strand of electrically insulative material, wherein each pass of the strand of material between opposing retaining means 30 is wrapped at least in part around respective shank 32 and cross member 34 before eventual joining of the ends of the strand at tie point 45.
  • the weaving and wrapping of the strand of material around shank 32 and cross member 34 is made to ensure that bridging means 37 will be fixedly held between respective retaining means 30 and to able bridging means 37 to withstand tension applied thereto, without slipping off shank 32 and/or cross member 34.
  • the plurality of strand segments forming arm 46 and 48 may be impregnated as hereinbefore described.
  • the number of strand segments constituting arms 46 and 48 is predeterminedly selected to provide the desired tensile strength for arms 46 and 48, which is a function of the tensile strength of a single strand of material and may be determined by one of ordinary skill in the art without undue experimentation. Since bridging means 37 comprises electrically insulative material, current flow between opposing cooperating retaining means 30 through bridging means 37 is prevented.
  • nuts 36 are predeterminedly tightened, thereby placing bridging means 37 under a predetermined amount of tension and ultimately urging channels 15 and 17 into compressive engagement with core 22 for inhibiting vibration of laminations 20.
  • bridging means 37 under a predetermined amount of tension and ultimately urging channels 15 and 17 into compressive engagement with core 22 for inhibiting vibration of laminations 20.
  • only one nut 36 may be used, if desired, with the other retaining means 30 fixedly secured to restraining means 27.
  • tensioning means 40 disposed in windows 16 and 18 may be similarly configured and function analogously to tensioning means 40 described above.
  • Tensioning means 40 comprises spindle means 54, such as a cylindrical member, which may be fixedly or removeably coupled to clamping channel 15 as desired, and a turnbuckle 50 having a T-bolt 52 threadably secured to one end thereof with the other end of turnbuckle 50 threadably secured to a threaded shank 58 which is in turn fixedly secured to or integral with restraining means 56, such as a block or a flange. Restraining means 56 may be fixedly or removeably coupled to clamping channel 17 as desired.
  • Spindle means 54 includes a groove or channel 55 disposed between the axial ends thereof and cut into the periphery thereof.
  • Groove 55 is preferably annular in cross-section so as not to include any sharp edges.
  • Tensioning means 40 further include bridging means 37, which include an electrically insulative material, and may be fabricated as hereinbefore described, secured to T-bolt 52 at one end thereof and disposed in groove 55 of spindle means 54.
  • turnbuckle 50 is tightened to apply a predetermined tension to bridging means 37, which in turn urges clamping channels 15 and 17 to compressively engage laminations 20 of core 22 as hereinbefore described.
  • a clamping device for adequately clamping the laminations of a core of a transformer without entirely encircling the mutual flux path with electrically conductive components, wherein the device is able to withstand long term, heavy cyclic thermal loads without adversely affecting the device. Further shown and described is a clamping device which increases the electrical insulative path length over prior devices while removing electrically conductive objects from between the coils of the transformer.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Housings And Mounting Of Transformers (AREA)
  • Coils Of Transformers For General Uses (AREA)
  • Organic Insulating Materials (AREA)
  • Insulating Of Coils (AREA)
EP87104861A 1986-04-29 1987-04-02 Transformer core support Withdrawn EP0246430A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US85789586A 1986-04-29 1986-04-29
US857895 1986-04-29

Publications (1)

Publication Number Publication Date
EP0246430A1 true EP0246430A1 (en) 1987-11-25

Family

ID=25326973

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87104861A Withdrawn EP0246430A1 (en) 1986-04-29 1987-04-02 Transformer core support

Country Status (4)

Country Link
EP (1) EP0246430A1 (zh)
JP (1) JPS62279611A (zh)
KR (1) KR870010574A (zh)
CN (1) CN87103257A (zh)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000002211A1 (de) * 1998-07-02 2000-01-13 Siemens Aktiengesellschaft Induktives bauteil mit einem kern
DE10144104A1 (de) * 2001-09-03 2003-04-03 Siemens Ag Haltevorrichtung
EP1703621A1 (de) * 2005-03-17 2006-09-20 Siemens Aktiengesellschaft Verspannung eines Blechpakets
DE102012104968A1 (de) * 2012-06-08 2013-12-12 Block Transformatoren-Elektronik Gmbh Verspannvorrichtung zum Verspannen eines Kerns eines induktiven Geräts
EP3667686A1 (en) * 2018-12-12 2020-06-17 Siemens Aktiengesellschaft Clamping bridge and clamping system for an electric transformer

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102592792A (zh) * 2012-02-29 2012-07-18 张家港新特变科技有限公司 变压器
CN104952592A (zh) * 2015-06-29 2015-09-30 宜兴市兴益特种变压器有限公司 一种磁性调压器铁芯夹紧装置

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB566642A (en) * 1943-10-11 1945-01-08 Cyril Cutler Improvements in small electric transformers
US3082390A (en) * 1959-07-09 1963-03-19 Cutler Hammer Inc Magnetic core structure
DE1189195B (de) * 1961-01-02 1965-03-18 Transformatoren Und Roentgen W Spannvorrichtung zum Verspannen der Schenkel bzw. Joche von lamellierten Magnetkernen
GB1043564A (en) * 1963-01-18 1966-09-21 Licentia Gmbh Improvements in and relating to magnetic cores
DE1233484B (de) * 1960-04-22 1967-02-02 Elin Union Ag Vorrichtung zur Jochpressung fuer Transformatoren mit geschichtetem Eisenkern
NL7102086A (zh) * 1971-02-17 1972-08-21
DE2339972A1 (de) * 1973-06-25 1975-01-16 Bbc Brown Boveri & Cie Abstuetz- bzw. pressvorrichtung fuer magnetkerne und wicklungen von transformatoren oder drosselspulen

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB566642A (en) * 1943-10-11 1945-01-08 Cyril Cutler Improvements in small electric transformers
US3082390A (en) * 1959-07-09 1963-03-19 Cutler Hammer Inc Magnetic core structure
DE1233484B (de) * 1960-04-22 1967-02-02 Elin Union Ag Vorrichtung zur Jochpressung fuer Transformatoren mit geschichtetem Eisenkern
DE1189195B (de) * 1961-01-02 1965-03-18 Transformatoren Und Roentgen W Spannvorrichtung zum Verspannen der Schenkel bzw. Joche von lamellierten Magnetkernen
GB1043564A (en) * 1963-01-18 1966-09-21 Licentia Gmbh Improvements in and relating to magnetic cores
NL7102086A (zh) * 1971-02-17 1972-08-21
DE2339972A1 (de) * 1973-06-25 1975-01-16 Bbc Brown Boveri & Cie Abstuetz- bzw. pressvorrichtung fuer magnetkerne und wicklungen von transformatoren oder drosselspulen

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000002211A1 (de) * 1998-07-02 2000-01-13 Siemens Aktiengesellschaft Induktives bauteil mit einem kern
DE10144104A1 (de) * 2001-09-03 2003-04-03 Siemens Ag Haltevorrichtung
EP1703621A1 (de) * 2005-03-17 2006-09-20 Siemens Aktiengesellschaft Verspannung eines Blechpakets
DE102012104968A1 (de) * 2012-06-08 2013-12-12 Block Transformatoren-Elektronik Gmbh Verspannvorrichtung zum Verspannen eines Kerns eines induktiven Geräts
EP3667686A1 (en) * 2018-12-12 2020-06-17 Siemens Aktiengesellschaft Clamping bridge and clamping system for an electric transformer
WO2020120248A1 (en) * 2018-12-12 2020-06-18 Siemens Aktiengesellschaft Clamping bridge and clamping system for an electric transformer

Also Published As

Publication number Publication date
CN87103257A (zh) 1987-12-16
KR870010574A (ko) 1987-11-30
JPS62279611A (ja) 1987-12-04

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Inventor name: VAN DUSEN, MORRIS VERNON