Source: http://www.google.com/patents/US5602710?dq=4316055
Timestamp: 2017-05-23 03:51:04
Document Index: 668772113

Matched Legal Cases: ['arts 3', 'arts 3', 'arts 3', 'arts 3', 'arts 3', 'arts 3', 'arts 3', 'arts 3', 'arts 3', 'arts 3', 'arts 3', 'arts4']

Patent US5602710 - Surge arrester - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsA surge arrester includes at least two connection fittings and a one-piece frame, the frame holding the connection fittings. The frame is formed of an insulating material. The surge arrester includes at least one block of varistor material clamped between the connection fittings. The surge arrester further...http://www.google.com/patents/US5602710?utm_source=gb-gplus-sharePatent US5602710 - Surge arresterAdvanced Patent SearchTry the new Google Patents, with machine-classified Google Scholar results, and Japanese and South Korean patents.Publication numberUS5602710 APublication typeGrantApplication numberUS 08/656,853Publication dateFeb 11, 1997Filing dateMay 30, 1996Priority dateSep 6, 1993Fee statusPaidAlso published asCA2130303A1, CN1043697C, CN1102904A, DE59401902D1, EP0642141A1, EP0642141B1Publication number08656853, 656853, US 5602710 A, US 5602710A, US-A-5602710, US5602710 A, US5602710AInventorsWalter Schmidt, Christoph SchupbachOriginal AssigneeAbb Management AgExport CitationBiBTeX, EndNote, RefManPatent Citations (5), Referenced by (39), Classifications (9), Legal Events (7) External Links: USPTO, USPTO Assignment, EspacenetSurge arrester
US 5602710 AAbstract
A surge arrester includes at least two connection fittings and a one-piece frame, the frame holding the connection fittings. The frame is formed of an insulating material. The surge arrester includes at least one block of varistor material clamped between the connection fittings. The surge arrester further includes an insulating material in which the frame, the block of varistor material and at least part of the connection fittings are cast to form a monolithic body. An arrangement is provided for maintaining a contact force between the connection fittings and the block of varistor material.
1. A surge arrester comprising:at least two connection fittings; a one-piece frame, the frame having a top end piece, a bottom end piece, and at least two connecting pans extending transversely relative to the top end piece and the bottom end piece and connecting the top end piece and the bottom end piece, the top end piece, the bottom end piece, and the at least two connecting parts forming a closed loop, the connection fittings being held in the top end piece and the bottom end piece of the frame, the frame being formed of an insulating material; at least one block of varistor material clamped between the connection fittings; an insulating material in which the frame, the at least one block of varistor material and at least part of the connection fittings are cast to form a monolithic body; and means for maintaining a contact force between the connection fittings and the at least one block of varistor material. 2. The surge arrester as claimed in claim 1, whereinthe frame forms at least pan of the maintaining means, the frame being resilient in an axial direction such that tension of the frame in the axial direction maintains the contact force between the connection fittings and the at least one block of varistor material. 3. The surge arrester as claimed in claim 1, whereinthe frame insulating material is fiber-reinforced. 4. The surge arrester as claimed in claim 3, wherein random fibers are used for fiber reinforcement of the frame.
5. The surge arrester as claimed in claim 3, wherein the frame insulating material includes a proportion of 10 to 80 percent by weight of the fibers for fiber reinforcement of the frame.
6. The surge arrester as claimed in claim 3, wherein the insulating material of the frame is glass-fiber reinforced.
7. The surge arrester as claimed in claim 6, wherein the frame insulating material includes a proportion of 30 to 50 percent by weight of glass fibers for glass fiber reinforcement of the frame.
8. The surge arrester as claimed in claim 1, wherein the frame is injection-molded or extruded from polymer material, or cast from epoxy resin.
9. The surge arrester as claimed in claim 1, wherein the connection fittings each include threaded pins.
10. The surge arrester as claimed in claim 9, wherein one of the threaded pins is connected rigidly to the frame.
11. The surge arrester as claimed in claim 1, wherein the frame is wound from at least one fiber-reinforced strand impregnated with epoxy resin.
12. The surge arrester as claimed in claim 11, wherein the strand is glass-fiber reinforced.
13. The surge arrester as claimed in claim 1, wherein the maintaining means includes one or more electrically conducting, resilient elements disposed between the connection fittings and the at least one block of varistor material for maintaining the contact force between the connection fittings and the at least one block of varistor material.
This application is a continuation of application Ser. No. 08/292,272, filed Aug. 18, 1994, now abandoned.
The invention is based on a surge arrester.
EP-A1-0 545 038 discloses a surge arrester having two fittings braced against each other by axially slightly resilient plastic strips. The plastic strips are guided with a form fit in the fittings. The surge arrester has cylindrically designed varistor elements, arranged one on top of the other to form a stack. Provided between the stack and the respective connection fitting is a spacer plate, which is pressed against the stack by means of a threaded bolt screwed into the fitting. The fittings bound the stack of varistor elements. Between the varistor elements and between the varistor elements and the electrically conducting spacer plates there are provided grooved disks for improving contact making. The arrangement described is encapsulated in insulating material.
The production of such a surge arrester from comparatively many individual parts requires a comparatively large number of working steps during assembly. In particular, the plastic strips have to be fitted very accurately into their guides in the fittings.
Accordingly, one object of this invention, as it is characterized in the independent claim 1, is to provide a novel surge arrester which can be produced with comparatively few working steps from parts which are simple and inexpensive to fabricate.
The surge arrester has at least two connection fittings, held by a frame, with at least one block of varistor material clamped between the connection fittings. In the case of the surge arrester, the frame, the at least one block and, in part, the connection fittings are cast in an insulating plastic material to form a monolithic body. The frame is designed in one piece and is fabricated from an insulating material. In addition, means which maintain the contact force between the connection fittings and the at least one block of varistor material are provided. The advantages achieved by this invention are to be seen essentially in that the assembly of the surge arrester, in particular the installation of the active part, is made significantly more simple and less expensive.
Either at least one electrically conducting, resilient element, for example a wave washer, or a frame which is resilient in the axial direction is provided as the means which maintains the contact force between the connection fittings and the at least one block of varistor material. In this way it is ensured that adequate contact force prevails during the entire lifetime of the surge arrester.
The insulating material of the frame is fibre-reinforced, in particular glass fibre-reinforced, so that the frame can be subjected to high mechanical loads. A frame which can be subjected to particularly high mechanical loads is obtained if random fibers are used for the fiber reinforcement of the frame. 10 to 80 percent by weight of fibers are incorporated for the fiber reinforcement of the frame. If glass fibers are used as reinforcement, a proportion of 30 to 50 percent by weight of glass fibers has been found to be favorable.
The frame can be produced particularly inexpensively if it is injection-molded or extruded from a polymer material or is cast from epoxy resin. If appropriate, the frame may also be wound from at least one fiber-reinforced strand impregnated with epoxy resin. The connection fittings are advantageously designed as threaded pins. It has proved to be particularly advantageous to connect one of the threaded pins rigidly to the frame.
The grooved disks ensure that a multiplicity of contact points are formed, for satisfactory current transfer. In addition, these soft grooved disks advantageously compensate for any unevennesses of the block surface, so that these unevennesses cannot reduce the current-carrying capability. It proves to be particularly advantageous that the grooved disks at the same time also seal the current transfer zones of the surge arrester against the penetration of insulating material during the casting operation for applying the casing.
Any further refinements of the invention are subjects of the dependent claims.
The invention, its further development and the advantages which can be achieved thereby are explained in more detail below with reference to the drawing, which represents merely one possible embodiment.
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood with reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
FIG. 1 shows a first partial section longitudinally through a first embodiment of the invention,
FIG. 2 shows a second partial section longitudinally through a second embodiment of the invention,
FIGS. 3 to 6 respectively show a section A--A, as it is indicated in FIG. 1, through various possible embodiments of the invention, and
FIG. 7 shows a partial section through a further possible embodiment of the invention.
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, in FIGS. 1 and 2 a longitudinal section is shown in diagrammatic representation through a surge arrester according to the invention, the surge arrester according to FIG. 2 being turned through 90° about its longitudinal axis with respect to that of FIG. 1. In these figures, the right-hand half of the surge arrester is in each case shown already encapsulated in an insulating compound. The surge arrester has a closed frame 1 of a one-piece design, made of an insulating material which can spring somewhat in the axial direction. Should the frame 1 not spring or not spring sufficiently, at least one resilient, electrically conducting element is provided, for example a wave washer la. The frame 1 has in each case at its ends facing the two connection sides of the surge arrester an elliptically or cylindrically designed end piece 2. The two end pieces 2 are held together here by two molded-on and symmetrically opposing connecting parts 3. An axially extended threaded pin 4 is screwed in each case into the elliptically or cylindrically designed end pieces 2. The threaded pins 4 serve as connection fittings for the electrical connections of the surge arrester. Here, for example, there are recessed into the end pieces 2 metallic threaded inserts 5, which guide the threaded pins 4 in a threaded bore, but a variety of possible ways in which permanently secure threads can be introduced into plastic parts are known. For instance, the threads may also be cut directly into the plastic of the frame 1. A shoulder 6 is molded onto the end face of each of the end pieces 2. On the side of the end pieces 2 facing away from the end face there is provided in the region of the transitions from the respective end piece 2 to the connecting parts 3 a cylindrically designed recess 7, in which a metallic pressure plate 8 is guided with clearance. The threaded pin 4 acts in each case directly on this pressure plate 8 if the frame 1 has resilient connecting parts 3. If the connecting parts 3 do not spring, or not strongly enough, electrically conducting, resilient elements are introduced between the pressure plate 8 and the threaded pin 4. The use of wave washers 1a has been found to be particularly favorable here. These wave washers 1a may be fitted only on one side of the surge arrester or, if greater forces are required, also on both sides of the surge arrester. Cup springs or wound springs may also be used as resilient elements.
Clamped between the two pressure plates 8 are blocks 9 of varistor material, such as for example ZnO. The blocks 9 are generally of a cylindrical design. Inserted between the pressure plates 8 and the respectively next block 9 is a cylindrically designed grooved disk 10, which has a central bore, and similarly there is always a grooved disk 10 inserted between neighboring blocks 9. The threaded pins 4 act on the pressure plates 8, possibly via the wave washers 1a. When introducing the described parts into the frame 1, it must be ensured that no gaps into which insulating material could penetrate during casting remain open between the parts. The actual contact force between the active parts is produced by the threaded pins 4, which are tightened with a predetermined torque and are subsequently secured against twisting in one of the known ways. Subsequently, onto each of the threaded pins 4 there is pushed a sealing disk 11, the cross section of which is adapted to the end piece 2 and is of an elliptical or cylindrical design here. The sealing disk 11 is preferably produced from a weather-resistant aluminum alloy, such as for example AlMg3. The sealing disk 11 may be fabricated from stainless steel, brass or bronze. The sealing disk 11 is pressed against the end face of the frame 1 in each case by means of a nut 12 screwed onto the respective threaded pin 4. The sealing disk 11 is to seal the finished surge arrester against environmental effects. Together with the shoulder 6, the sealing disk 11 forms a groove, which is filled with electrically insulating plastic during encapsulation.
The thus preassembled arrangement is placed into a mold and encapsulated with a casing 13 of electrically insulating plastic, without any gaps or voids, up to the sealing disk 11. A suitable plastic for this is, for example, silicone rubber. During encapsulating, at the same time insulating shields 14 are molded onto the casing 13. The threaded pins 4 which are required for the electrical connections of the surge arrester remain as bare metal.
The frame 1 of the surge arrester is preferably produced from a glass fiber-reinforced nylon 6.6 in an injection-molded process, the proportion of glass fibers in this case lying in a range from 30 to 50 percent by weight. A particularly sturdy frame 1 is obtained if the glass fibers are incorporated as random fibers. Apart from the nylon 6.6 mentioned, nylon 610, nylon 11 and also nylon 12 may also be used for the production of the frame 1. Furthermore, it is possible also to use recycled products based on the polyamides mentioned, in particular whenever the surge arresters do not have to meet particularly high requirements for cantilever strength. The frame 1 may, however, also be machined from a corresponding solid material. It is also possible to wind the frame 1 with the aid of a resin-impregnated glass fiber filament or tape. In a normal case, the frame 1 is fabricated in the size adapted to the respective overall size of the surge arrester, so that no additional adapting work is necessary on the frame 1. In small series, however, it may prove to be necessary for reasons of cost-effectiveness to adapt the frame 1 to various overall sizes of the surge arrester. For this purpose it is possible to divide up the connecting parts 3 and lengthen them by corresponding intermediate pieces. However, these intermediate pieces must be inserted absolutely securely.
In FIG. 1 the section A--A is entered. FIGS. 3 to 6 show the section A--A, as it could appear in the case of various possible embodiments of the invention. In FIG. 3 there is shown, for example, an elliptically designed casing 13, which surrounds the blocks 9. In this case, the cross-sections of the connecting parts 3 are adapted to the shape of the casing 13. In FIG. 4 there is shown a cylindrically designed casing 13, which surrounds the blocks 9. In this case, the cross sections of the connecting parts 3 are adapted to the shape of the casing 13. In FIG. 5 there is shown a substantially rectangularly designed casing 13, which surrounds the blocks 9. In this case, the cross sections of the connecting parts 3 are adapted to the shape of the casing 13. In FIG. 6 there is shown an arrangement which has not yet been provided with a casing. In this case, the connecting parts 3 are arranged unsymmetrically, but such that the frame 1 has on the one side an opening 15 which allows the assembly of the blocks 9. This frame 1 is provided with a cylindrically designed casing 13, therefore the cross sections of the connecting parts 3 are also adapted here to the shape of the casing 13. Such a frame 1 is particularly torsion-resistant and is used for surge arresters which are designed for particularly high bending loads.
The grooved disk 10 has a central bore. A multiplicity of grooves surround this bore concentrically. The grooved disk is produced from soft-annealed aluminum. The outermost edge of the outermost grooves in each case serves as a sealing edge against plastic penetrating during casting. A variety of groove shapes can be imagined, but on the outside there must always be formed an adequate sealing edge and, moreover, it must be ensured that an adequate number of contact points for the electrical contact can form during the assembly of the grooved disks 10.
It can also be imagined that only one of the threaded pins 4 is used for producing the contact force, while the other is cast solidly with the frame 1 already during production of the latter, as shown in FIG. 7. This threaded pin 4 has a shaped piece 16, which is rigidly connected to it; this may be, for example, a nut adhesively bonded to it, the hexagon of which makes twisting of the threaded pin 4 in the frame 1 impossible. In this case, the contact force is produced by the opposite threaded pin 4 alone.
To explain the operating principle, the figures described will be considered in a little more detail. The contact force which is applied by the threaded pins 4 to the arrangement ensures that the edges of the grooved disks 10 deform locally, giving rise to defined punctiform contacts, which allow a particularly good current transfer in the surge arrester. The best current transfer is achieved if there are a multiplicity of such punctiform contacts, which are distributed uniformly over a surface area. The grooved disks 10 make possible this multiplicity of punctiform contacts. In this way it is ensured that the comparatively very high current flowing when the surge arrester responds is always discharged reliably through the active part of the surge arrester, without an overloading of certain places where there is current transfer and an associated scorching, which causes defects, being able to occur. The operational reliability of the arrester is considerably increased in this way.
Furthermore, it serves for operational reliability that the contact force mentioned is maintained over the entire lifetime of the surge arrester, since either the frame 1 springs somewhat in the axial direction, so that it expands somewhat during tightening of the threaded pins and maintains this prestressing, or additional resilient elements, such as the wave washers 1a, maintain the prestressing. An interaction between frame 1 and these resilient elements is also possible. This prestressing is chosen such that there is also reliable compensation at all times for any shrinking of the grooved disks 10.
It is advantageously ensured by the casting of the entire arrangement into the casing 13 and by the sealing disks 11 that both the blocks 9 and the frame 1 with the connecting parts 3 cannot absorb any moisture from the ambient air, so that their dielectric strength is not reduced. The monolithic body into which the finished surge arrester is formed has a high mechanical stability, in particular also with regard to cantilever strength, and in addition it is insensitive to decomposing climatic effects, so that it can be used advantageously in all climatic zones.
______________________________________LIST OF DESIGNATIONS______________________________________1                Frame1a               Wave washers2                End piece3                Connecting parts4                Threaded pin5                Threaded insert6                Shoulder7                Recess8                Pressure plate9                Block10               Grooved disk11               Sealing disk12               Nut13               Casing14               Screen15               Opening16               Shaped piece______________________________________
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS4853670 *Feb 19, 1988Aug 1, 1989Asea Brown Boveri AbSurge arresterUS4930039 *Apr 18, 1989May 29, 1990Cooper Industries, Inc.Fail-safe surge arresterUS5043838 *Sep 20, 1989Aug 27, 1991Hubbell IncorporatedModular electrical assemblies with pressure reliefUS5291366 *Oct 26, 1992Mar 1, 1994Asea Brown Boveri Ltd.Surge voltage arresterEP0545038A1 *Oct 10, 1992Jun 9, 1993Asea Brown Boveri AgSurge arrester* Cited by examinerReferenced byCiting PatentFiling datePublication dateApplicantTitleUS5831808 *Oct 19, 1995Nov 3, 1998Girard; FrancoisLightning arrester deviceUS5930102 *Oct 8, 1997Jul 27, 1999Joslyn Manufacturing Co.Surge arrester having single surge arresting blockUS6279811May 12, 2000Aug 28, 2001Mcgraw-Edison CompanySolder application techniqueUS6421909May 5, 1999Jul 23, 2002Joslyn Manufacturing Co.Method for isostatically pressing a surge arresting blockUS6519129Nov 2, 1999Feb 11, 2003Cooper Industries, Inc.Surge arrester module with bonded component stackUS6575355Jun 5, 2001Jun 10, 2003Mcgraw-Edison CompanySolder application techniqueUS6678139Jun 13, 2000Jan 13, 2004Abb Research LtdHigh voltage lead-throughUS6840432 *Apr 21, 2003Jan 11, 2005Mcgraw-Edison CompanySolder application techniqueUS6847514Dec 20, 2002Jan 25, 2005Cooper Industries, Inc.Surge arrester module with bonded component stackUS7015786 *Aug 29, 2001Mar 21, 2006Mcgraw-Edison CompanyMechanical reinforcement to improve high current, short duration withstand of a monolithic disk or bonded disk stackUS7075406Mar 16, 2004Jul 11, 2006Cooper Technologies CompanyStation class surge arresterUS7436283Nov 20, 2003Oct 14, 2008Cooper Technologies CompanyMechanical reinforcement structure for fusesUS7633737Apr 29, 2004Dec 15, 2009Cooper Technologies CompanyLiquid immersed surge arresterUS7660093Nov 20, 2007Feb 9, 2010Hubbell IncorporatedArrester block module assembly and methodUS8085520Apr 16, 2010Dec 27, 2011Cooper Technologies CompanyManufacturing process for surge arrester module using pre-impregnated compositeUS8117739Jan 23, 2004Feb 21, 2012Cooper Technologies CompanyManufacturing process for surge arrester module using pre-impregnated compositeUS8717732 *Jun 4, 2012May 6, 2014Abb Research Ltd.High voltage surge arresterUS9437354 *Aug 1, 2012Sep 6, 2016Marco Antonio Ponce VélezVoltage surge protector having a pressure release mechanismUS9524815Nov 5, 2013Dec 20, 2016Abb Schweiz AgSurge arrester with moulded sheds and apparatus for mouldingUS20030070968 *Oct 12, 2002Apr 17, 2003Professional Dental ManufacturingWater filtering apparatusUS20040257742 *Jul 11, 2002Dec 23, 2004Peter ZellerVoltage limiterUS20050000867 *Jun 16, 2004Jan 6, 2005Professional Dental ManufacturingWater filtering apparatusUS20050110607 *Nov 20, 2003May 26, 2005Babic Tomas I.Mechanical reinforcement structure for fusesUS20050160587 *Jan 23, 2004Jul 28, 2005Ramarge Michael M.Manufacturing process for surge arrester module using pre-impregnated compositeUS20050207084 *Mar 16, 2004Sep 22, 2005Ramarge Michael MStation class surge arresterUS20050243495 *Apr 29, 2004Nov 3, 2005Ramarge Michael MLiquid immersed surge arresterUS20060152878 *Mar 21, 2006Jul 13, 2006Ramarge Michael MMechanical reinforcement to improve high current, short duration withstand of a monolithic disk or bonded disk stackUS20100194520 *Apr 16, 2010Aug 5, 2010Mcgraw-Edison CompanyManufacturing process for surge arrester module using pre-impregnated compositeUS20100307793 *Oct 28, 2008Dec 9, 2010Siemens AktiengesellschaftInsulator arrangementUS20120250207 *Jun 4, 2012Oct 4, 2012Stenstroem LennartHigh Voltage Surge ArresterUS20150340134 *Aug 1, 2012Nov 26, 2015Mappec Materiales-Productos Poliméricos Y Elementos De Construcción, S. A. De C. V.Voltage surge protector having a pressure release mechanismCN102648501A *Dec 2, 2010Aug 22, 2012Abb研究有限公司A high voltage surge arresterCN102725805A *Feb 4, 2011Oct 10, 2012Abb 技术有限公司Surge arresterCN102725805B *Feb 4, 2011Mar 9, 2016Abb 技术有限公司过压防护放电器DE102007057265A1 *Nov 26, 2007May 28, 2009Siemens AgIsolatoranordnungEP1143460A1 *Apr 3, 2001Oct 10, 2001Kabushiki Kaisha ToshibaSurge arresterEP3023998A1Nov 21, 2014May 25, 2016ABB Technology AGMulti-terminal surge arresterWO2000077904A1 *Jun 13, 2000Dec 21, 2000Abb Research Ltd.High voltage lead-throughWO2003021608A1 *Jul 12, 2002Mar 13, 2003Mcgraw-Edison CompanyMechanical reinforcement to improve high current, short duration withstand of a monolithic disk or bonded disk stack* Cited by examinerClassifications U.S. Classification361/127, 361/117International ClassificationH01T4/02, H01T4/06, H02H9/04, H01T1/16, H01C7/12Cooperative ClassificationH01C7/12European ClassificationH01C7/12Legal EventsDateCodeEventDescriptionNov 4, 1996ASAssignmentOwner name: ABB MANAGEMENT AG, SWITZERLANDFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:SCHMIDT, WALTER;SCHUPBACH, CHRISTOPH;REEL/FRAME:008235/0651Effective date: 19940810Jan 14, 1997ASAssignmentOwner name: ASEA BROWN BOVERI AG, SWITZERLANDFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:ABB MANAGEMENT AG;REEL/FRAME:008322/0246Effective date: 19961223Jul 21, 2000FPAYFee paymentYear of fee payment: 4Jun 25, 2002ASAssignmentOwner name: ABB SCHWEIZ HOLDING AG, SWITZERLANDFree format text: CHANGE OF NAME;ASSIGNOR:ASEA BROWN BOVERI AG;REEL/FRAME:013000/0190Effective date: 20011211Aug 6, 2004FPAYFee paymentYear of fee payment: 8Apr 22, 2005ASAssignmentOwner name: ABB ASEA BROWN BOVERI LTD., SWITZERLANDFree format text: MERGER;ASSIGNOR:ABB SCHWEIZ HOLDING AG;REEL/FRAME:016145/0053Effective date: 20041201Owner name: ABB SCHWEIZ AG, SWITZERLANDFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:ABB ASEA BROWN BOVERI LTD.;REEL/FRAME:016145/0062Effective date: 20050320Aug 7, 2008FPAYFee paymentYear of fee payment: 12RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services