CA1334990C - Modular electrical assemblies with pressure relief - Google Patents
Modular electrical assemblies with pressure reliefInfo
- Publication number
- CA1334990C CA1334990C CA000587516A CA587516A CA1334990C CA 1334990 C CA1334990 C CA 1334990C CA 000587516 A CA000587516 A CA 000587516A CA 587516 A CA587516 A CA 587516A CA 1334990 C CA1334990 C CA 1334990C
- Authority
- CA
- Canada
- Prior art keywords
- assembly according
- winding
- openings
- modular electrical
- electrical assembly
- 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.)
- Expired - Lifetime
Links
- 230000000712 assembly Effects 0.000 title description 14
- 238000000429 assembly Methods 0.000 title description 14
- 238000009730 filament winding Methods 0.000 claims abstract description 24
- 239000011810 insulating material Substances 0.000 claims abstract description 20
- 238000013022 venting Methods 0.000 claims abstract description 13
- 239000004593 Epoxy Substances 0.000 claims abstract description 10
- 239000004519 grease Substances 0.000 claims abstract description 8
- 238000004804 winding Methods 0.000 claims description 34
- 229910044991 metal oxide Inorganic materials 0.000 claims description 8
- 150000004706 metal oxides Chemical class 0.000 claims description 8
- 230000004888 barrier function Effects 0.000 claims description 7
- 230000006835 compression Effects 0.000 claims description 6
- 238000007906 compression Methods 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 5
- 238000005452 bending Methods 0.000 claims description 3
- 229910003460 diamond Inorganic materials 0.000 claims description 3
- 239000010432 diamond Substances 0.000 claims description 3
- 230000004323 axial length Effects 0.000 claims 2
- 239000003822 epoxy resin Substances 0.000 claims 1
- 229920000647 polyepoxide Polymers 0.000 claims 1
- 229920001296 polysiloxane Polymers 0.000 abstract description 4
- 239000007789 gas Substances 0.000 description 20
- 239000002985 plastic film Substances 0.000 description 6
- 230000006378 damage Effects 0.000 description 4
- 238000013461 design Methods 0.000 description 4
- 239000000835 fiber Substances 0.000 description 4
- 229920006255 plastic film Polymers 0.000 description 4
- 238000010276 construction Methods 0.000 description 3
- 230000009545 invasion Effects 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 2
- 238000011068 loading method Methods 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000003190 augmentative effect Effects 0.000 description 1
- 230000009172 bursting Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000011152 fibreglass Substances 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- -1 polypropylene Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
- 230000001012 protector Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229920002545 silicone oil Polymers 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
- H01T1/00—Details of spark gaps
- H01T1/15—Details of spark gaps for protection against excessive pressure
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
- H01C7/10—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material voltage responsive, i.e. varistors
- H01C7/12—Overvoltage protection resistors
- H01C7/126—Means for protecting against excessive pressure or for disconnecting in case of failure
Landscapes
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Thermistors And Varistors (AREA)
- Emergency Protection Circuit Devices (AREA)
- Multi-Conductor Connections (AREA)
- Coils Or Transformers For Communication (AREA)
- Linear Motors (AREA)
Abstract
A modular electrical assembly is enclosed in an elastomeric weathershed housing, and has a plurality of electrical components aligned in a row and in electrical connection with one another via their axially-directed ends and under an axially-directed compressive force via a non-conductive filament winding. The filament winding defines a crisscross pattern with lateral openings for venting gas upon failure of one of the electrical components. The openings can be filled with fracturable epoxy or other insulating materials such as silicone grease.
Description
133~990 MODULAR ELECTRICAL
ASSEMBLIES WITH PRESSURE RELIEF
Field of the Invention The present invention relates to polymer housed electrical assemblies which are formed as modules and which can ~e selectively coupled together to vary the overall electrical rating of the device. Each electrical assembly is formed from electrical components that are wrapped with a non-conductive filament winding in a pattern with lateral openin~s for relieving gas pressure. The components can be varistors, resistors, capacitors, or any combination thereof.-'$
i - 2 - 1 ~ 3 4 9 9 ~
Background of the Invention A surge protector or arrester is commonly connected across a comparatively expensive piece of electrical equipment to shunt over-current surges. Such over-current surges occur, for example, when lightning strikes. When this happens, the surge arrester shunts the surge to ground, thereby protecting the piece of electrical equipment and the circuit from damage or destruction.
Present day surge arresters commonly include an elongated, hollow cylindrical housing made of porcelain or the like, and a plurality of non-linear resistive blocks within the housing. Some of these structures also include spark gaps, the blocks and gaps being electrically interconnected to handle voltage and current surge conditions arising on a power line. The blocks commonly contain silicone carbide (SIC) or metal oxide varistors (MOV), and are usually in the shape of relatively short cylinders stacked within the arrester housing. The number of blocks employed is a function of the material (SIC or MOV) and the voltage and current ratings of the assembly.
For a surge arrester to function properly, intimate contact must be maintained between the MOV or SIC blocks.
This necessitates placing an axial load on the blocks within the housing. Prior art arresters utilize bulky contact springs within the housing to provide this axial load.
Typically, these springs can provide only relatively small loads, for example, about sixty pounds. As a result, prior art fiurge arresters experience one or more problems such as poor heat transfer between the MOV or SIC blocks and arrester terminals; non-uniform current distribution; and high contact resistances at joints. Furthermore, units having low contact force sputter and the ionized metal which iR pr,oduced can cause axial flashover at high currents.
An additional problem with surge arresters of the prior art is that they, on rare occasions, fail in a dangerous fashion. When these arresters fail and experience high fault currents producing high internal gas pressures, the bursting unit may throw parts and cause ~roperty damage.
In addition, some of the prior art devices are difficult to assemble, have poor dielectric design, are susceptible to water invasion, and require totally different devices to provide varied voltage ratings.
Examples of prior art surge arresters are disclosed in the following U.S. patents: 2,587,587 to Bellezza et al;
2,947,903 to Westrom; 2,997,529 to Fink; 3,018,406 to Innis;
ASSEMBLIES WITH PRESSURE RELIEF
Field of the Invention The present invention relates to polymer housed electrical assemblies which are formed as modules and which can ~e selectively coupled together to vary the overall electrical rating of the device. Each electrical assembly is formed from electrical components that are wrapped with a non-conductive filament winding in a pattern with lateral openin~s for relieving gas pressure. The components can be varistors, resistors, capacitors, or any combination thereof.-'$
i - 2 - 1 ~ 3 4 9 9 ~
Background of the Invention A surge protector or arrester is commonly connected across a comparatively expensive piece of electrical equipment to shunt over-current surges. Such over-current surges occur, for example, when lightning strikes. When this happens, the surge arrester shunts the surge to ground, thereby protecting the piece of electrical equipment and the circuit from damage or destruction.
Present day surge arresters commonly include an elongated, hollow cylindrical housing made of porcelain or the like, and a plurality of non-linear resistive blocks within the housing. Some of these structures also include spark gaps, the blocks and gaps being electrically interconnected to handle voltage and current surge conditions arising on a power line. The blocks commonly contain silicone carbide (SIC) or metal oxide varistors (MOV), and are usually in the shape of relatively short cylinders stacked within the arrester housing. The number of blocks employed is a function of the material (SIC or MOV) and the voltage and current ratings of the assembly.
For a surge arrester to function properly, intimate contact must be maintained between the MOV or SIC blocks.
This necessitates placing an axial load on the blocks within the housing. Prior art arresters utilize bulky contact springs within the housing to provide this axial load.
Typically, these springs can provide only relatively small loads, for example, about sixty pounds. As a result, prior art fiurge arresters experience one or more problems such as poor heat transfer between the MOV or SIC blocks and arrester terminals; non-uniform current distribution; and high contact resistances at joints. Furthermore, units having low contact force sputter and the ionized metal which iR pr,oduced can cause axial flashover at high currents.
An additional problem with surge arresters of the prior art is that they, on rare occasions, fail in a dangerous fashion. When these arresters fail and experience high fault currents producing high internal gas pressures, the bursting unit may throw parts and cause ~roperty damage.
In addition, some of the prior art devices are difficult to assemble, have poor dielectric design, are susceptible to water invasion, and require totally different devices to provide varied voltage ratings.
Examples of prior art surge arresters are disclosed in the following U.S. patents: 2,587,587 to Bellezza et al;
2,947,903 to Westrom; 2,997,529 to Fink; 3,018,406 to Innis;
3,261,910 to Jacquier; 3,412,273 to Kennon et al; 3,524,107 to Reitz; 3,566,183 to Olsen; 3,567,541 to Xaczerginski;
3,586,934 to Nakata; 3,706,009 to Reitz;~ 3,725,745 to Zisa;
3,850,722 to Kreft; 3,973,172 to Yost; 3,987,343 to Cunningham et al; 4,029,380 to Yonkers; 4,092,694 to Stetson; 4,100,588 to Kresge; 4,107,567 to Cunningham et al;
3,586,934 to Nakata; 3,706,009 to Reitz;~ 3,725,745 to Zisa;
3,850,722 to Kreft; 3,973,172 to Yost; 3,987,343 to Cunningham et al; 4,029,380 to Yonkers; 4,092,694 to Stetson; 4,100,588 to Kresge; 4,107,567 to Cunningham et al;
4,161,012 to Cunningham; 4,218,721 to Stetson; 4,404,614 to 20, Koch et al; 4,467,387 to Bergh et al; 4,491,687 to Kaczerginski et al; and U.S. Defensive Publication T102,103, as well as U.K. patents 730,710; 1,109,151; and 1,505,875.
In the surge arresters of commonly assigned U.S. Patent No. 4,656,555 to Raudabaugh, copending Canadian patent application Serial No. 590,452 of Donald E. Raudabaugh entitled Polymer Housed Electrical Assemblies Using Modular Construction and filed February ~, 1989, and Canadian patent application Serial No. 587,515 filed January 4, 1989 entitled Modular Electrical Assemblies with Plastic Film sarriers of Donale E. Raudabaugh, resin soaked glass fibers completely surround and axially compress the varistor blocks. This complete enclosure of the varistor blocks may not~permit the gases generated upon varistor block failure to escape to the weathershed housing interior and then out of the weathershed housing before the gas pressure becomes too great and causes the assembly to break apart. If the 'SJs ~
filament wrap is relatively thin, the wrap can be burned through or can split before an extremely high pressure develops.
Summary of the Invention Accordingly, this invention seeks to provide electrical assemblies, particularly for surge arresters, which can vent gases generated upon electrical component failure to minimize damage, are relatively simple and inexpensive to manufacture, have good dielectric design, resist water invasion and have modular components and housings to simply vary voltage ratings.
Further the invention seeks to provide electrical assemblies, such as surge arresters, having high axial loadings, thereby resulting in uniform current distribution, low contact resistances at joints and excellent heat transfer to the arrester terminals.
Still further the invention seeks to provide an electrical assembly, such as a surge arrester, having a shatter-proof housing which has a high-impact strength and which does not fail in a dangerous fashion.
The invention in one aspect provides a modular electrical assembly, comprising a plurality of conductive electrical components, aligned in a column along an axis and having axially directed ends, the electrical components being electrically connected at the axially directed ends. First and second conductive end members are located at opposite ends of the column, each end member having a shoulder extending radially relative to the axis. A non-conductive winding is wrapped in a predetermined pattern longitudinally and crosswise about the electrical components and the end members, engaging the shoulders and applying an axially directed compressive force through tne shoulders on the electrical components and end members to maintain electrical connection therebetween. The winding has a first plurality of strand portions forming a first layer and a first opening therein and having a second plurality of strand portions forming a second layer and a second opening therein, the first and second openings having substantially the same shape and being substantially aligned to form a common -- opening for venting gas upon failure of one of the electrical components, the common opening extending completely through the winding radially relative to the axis.
Another aspect of the invention provides a surge arrester, comprising a plurality of generally cylindrical, metal oxide varistor blocks aligned in a column along an axis and having axially directed ends, the varistor blocks being in electrical connection with one another through the axially directed ends.
~.
, ,1 s 1334990 First and second generally cylindrical, conductive terminals are at opposite ends of each column, each terminal having a first axial end in contact with one of the varistor blocks and an opposite second axial end with an internally threaded socket, 5 the varistor blocks and the terminals having substantially equal transverse diameters. Compression means is wrapped longitudinally and crosswise around the varistor blocks and the ter~inals in a predetermined criss-cross pattern, for applying an axially-directed compressive force on the varistor blocks and the terminals to maintain electrical connection thereof, the compression means including a non-conductive filament winding having a first plurality of strand portions forming a first layer and first openings therein and a second plurality of strand portions forming a second layer and second openings therein. Respective first and second openings have substantially the same shape and are substantially aligned to form common preformed lateral openings in the winding for venting gas upon failure of one of the varistor blocks, the lateral openings completely through the winding radially relative to the axis. Elastomericl weathershed means, resiliently encloses the varistor blocks, for protecting the varistor blocks, the weathershed means having a substantially cylindrical throughbore with a diameter substantially equal to transverse diameters of the compression means.
Still further the invention provides an electrical surge arrester assembly, comprising a plurality of cylindrical surge arrester components arranged substantially coaxially to form a cylindrical stack of components having a longitudinal axis, the components having non-linear voltage-current characteristics and first and second electrically conductive terminals mounted at opposite respective ends of the stack and electrically coupled to the components, the terminals having radial surface portions substantially concentric with respect to the longitudinal axis.
A non-conductive tubular member encompasses the stack longitudinally and crosswise and has first and second opposite ends with radially projecting parts engaging and connected respectively to the first and second radial surface portions of the t,erminals, the tubular member having sufficient structural strength to apply an axially-directed compressive force by way of the terminals to the arrester components sufficient to maintain electrical contact between the components of the stack and the terminals. The tubular member is a winding having a first plurality of strand portions forming a first layer and a first opening therein and having a second plurality of strand 133~990 portions forming a second layer and a second opening therein, the first and second openings having substantially the same shape and being substantially aligned to form a common opening providing preformed venting means to facilitate lateral egress s therethrough of gaseous products produced by the stack. A
housing encompasses the tubular member and cooperates therewith to at least partially control the expulsion of the gaseous products from the assembly.
The invention still further provides a modular electrical assembly, comprising a plurality of conductive electrical components aligned in a row along an axis and has axially directed ends, at which they are electrically interconnected and at opposite ends of the row, there are first and second conductive end members. A non-conductive filament winding is wrapped longitudinally and crosswise about the electrical components and the end members and applies an axially directed compressive force on the electrical components and end members to maintain electrical connection therebetween. The winding has preformed lateral openings for venting gas upon failure of one of the electrical components, the lateral openings extending through the winding radially relative to the axis.
There is provided in a preferred aspect a modular electrical assembly including a plurality of conductive electrical components aligned in a row or column and electrically connected through their axially directed ends and a non-conductive fiber filament winding wrapped about the electrical components. The winding applies an axially directed compressive force on the electrical components to maintain their electrical connection and defines a pattern with lateral openings therein for venting gases generated upon failure of one of the electrical components.
Other aspects, advantages and salient features of the invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the invention.
Brief Description of the Drawings Referring to the drawings which form a part of this original disclosure:
Fig. 1 is a side elevational view in partial section of a modular electrical assembly in the form of a surge arrester, in accordance with the present invention, illustrating the outer surface of the filament winding;
Fig. 2 is a side elevational view in longitudinal section of the assembly illustrated in Fig. 1;
'-1'~ ~
` - :
- 5B - 133~990 Fig. 3 is an enlarged end elevational view in section taken along line 3 - 3 of Fig. 1;
Fig. 4 is an end elevational view of the end member of Figs. 1 and 2;
Fig. 5 is a side elevational view in section of the end member taken along line 5 - 5 of Fig. 4;
Fig. 6 is a side elevational view of the end member of Fig.` 4; and Figs. 7 - 9 are diagrammatic illustrations of the wrap pl'an for forming the pattern of the filament winding of Fig. 1.
Detailed Description of Preferred Embodiment Referring to Figs. 1 - 3, an electrical device 50, in the form of a surge arrester, according to the present invention is formed of a modular electrical assembly 52, enclosed in a polymeric, elastomeric weathershed housing 58.
The illustrated electrical assembly can be advantageously substantially identical to and interchangeable with the 1 33~ g90 other electrical assemblies, and is in turn formed from one or a plurality of cylindrical electrical components 60 and 62. These components are aligned in a row, and are in electrical connection with one another throush their axially-directed ends and under an axially-directed compressive force developed by a non-conductive filament winding 64, as disclosed in U.S. Patent No. 4,656,555 and ~anadian Serlal No. ~0,452. The electrical components can be metal oxide varistors (e.g. zinc oxide varistor blocks), `; resistors, capacitors or any combination thereof.
In the case of varistors used to form a surqe arrester, voltage ratings can be enlarged merely by serially and selectively coupling the plurality of modular electrical assemblies together mechanically and electrically.
The elastomeric weathershed housing S8 receives the electrical assemblies therein via a slight interference fit, ~his facilitates construction and allows the practice of good dielectric design by reducing radial gaps.
Electrical assembly 52 has a substantially cylindrical overall outer surface and comprises first end member, or terminal 72, spring washer 74, contact disc 76, electrical component 60, contact disc 78, electrical component 62, contact disc 80, spring washer 82, and second end member or terminal 84. Additional spring washers can be employed in the electrical assembly against the contact discs at some or all of the intermediate varistor joints, particularly for base mounted assemblies, to maintain contact pressure when the assembly bends under cantilever loading. ~he - non-cor.ductive filament winding 64 is coupled to end members 72 and 84, encloses the electrical components, and maintains them under an axially-directed force, which is augmented by the spring washers.
~ A plastic film barrier 110 laterally surrounding electrical components 60 and 62 is interposed coaxially between the electrical components and filament winding 64.
Preferably~ the plastic is polypropylene. The barrier 110 is formed by wrapping a rectangular plastic sheet tightly about 13~4990 the electrical components and the adjacent portions of end members 72 and 84 in pre~erably two layers before filament winding 64 is added. The thickness of the plastic sheet and of each layer is about 0.0005 inch.
Since the plastic film barrier extends along the entire length of the electrical components and onto the end members, the plastic film barrier seals the electrical components from the epoxy or resin on the filament forming the winding. For surge arresters, this prevents the wet epoxy or resin on the filament from bonding to the fragile ceramic insulating collars on the metal oxide varistor blocks 60 and 62. Such bonding can be prevented by other adhesion blockers, such as silicone oil or grease.
Advantageously, end members 72 and 84 are formed from aluminum. They can also be formed of any other material with suitable conductivity and mechanical strength.
End members 72 and 84 form internal terminals, have cylindrical exposed outer surfaces, and have opposite, first and second axially-directed planar ends with internally threaded sockets or bores 86 and 88 formed respectively therein. Socket 86 threadedly receives threaded end stud 90 which can be connected to an electrical power source and is in the form of a metallic, conductive bolt with an internally threaded nut 91. End plate 92 is received on end stud 90, tightly engages an end of the weathershed housing as seen in Figs. 1 and 2 and is held in place via rigid nut 91 on the stud. For base mounting, a base plate with a bolt circle can be attached. A second end plate 96 is similarly positioned at the other end of the housing and is received on end stud 98 which is connected to ground and maintained thereon via internally threaded nut 99 on the stud. Studs 90 and 98 in essence form external terminals for the overall device 50.
'Weathershed housing S8 has a through passageway in the form of a throughbore with an inwardly facing cylindrical surface 100 which tightly receives therein the outer cylindrical surface of the electrical assembly 52. The reception of the assembly in the throughbore is preferably -via an interference fit with the assembly having an outer surface diameter that $s about 2~ to about 9~ greater than the throughbore diameter and is substantially constant along its length. This reduces radial gaps and thus provides advantageous dielectric design.
Since end members 72 and 84 are identical, only end member 72 i8 described in detail. Referring particularly to Figs. 4-6 end member 72 comprises an inner section 120 and an outer section 122 separated by a radially extending flange 124. Inner section 120 is oriented adjacent the electrical components 60 and 62 and has a cylindrical lateral surface with a transverse diameter substantially equal to the electrical components. Inner section 120 defines that portion of the end member which receives film - 15 barrier 110. Outer section 122 also has a cylindrical lateral surface, but has a transverse diameter substantially less than inner section 120.
Flange 124 is generally circular in plan view and extends radially outwardly from the interface between sections 120 and 122. Radially inwardly extending and radially outwardly opening notches 126 are formed in the flange. Eight uniformally dimensioned notches are evenly and circumferentially spaced about flange 124 in the illustrated embodiment. The number of notches will vary depending upon the component diameter. More notches will be used w~th larger component diameters, and less notches will be used with smaller component diameters, The end members facilitate wrapping a non-conductive filament, e.g., glass in a pattern with diamond shaped lateral openings 128. Openings 128 are filled with a fracturable insulating material 130 having suitable insulating and mechanical characteristics, for example epoxy. Other suitable insulating materials include polyester, foam, rubber, silicone grease or gas, such as air. If the housing is molded about the electrical assembly wrap, the molded housing material can fill the openings.
The crisscross winding pattern illustrated in Fig. 1 is formed by wrapping one filament, or preferably a plurality of filaments simultaneously (typically 9) according to the pattern diagrammatlcally illustrated in Figs. 7-9 wherein the end member notches 126 are 6paced at 45 angl~es. The wrap plan used for a particular arrester will depend on component diameter, length and mechanical requirements. In these figures, end members 72 and 84 are denoted by the letters "L~ and "R" in Figs. 7 and 9, respectively. The individual notches 126 in each end member are numbered 1 through 8, respectively. In passing from end member to the other, the assembly i5 rotated through 180 as a filament is moved axially. Subsequently, the filament is rotated at the end member through an angle of 315 to the next notch position. This specific pattern illustrated is as follows and is illustrated in Fig. 8:
From To Rotation lL 5R 180 5L lR 180 lR 8R 315 iL 3L 315 2L lL 315 The pattern is repeated until the filament develops a thick~ess equal to the lateral peripheral extent of flange 124. Additional fiber filament is wound about the outer sections 122 until the filament surrounding such sections has a~ outer peripheral surface at least equal to the outermost extension of the flange. The outer surface of the assembly is then abraded to the extent necessary to provide a uniform cylindrical surface along its entire length.
r The insulating material 130 fills the openings 128 to maintain the desired uniform cylindrical surface of assembly 52. However, insulating material 130 can readily break or separate upon the development of adequate internal pressure within the winding, which pressure exceeds the' threshold level permitted by epoxy or other insulating material against rupture, to permit gas to vent.
Upon electrical component failure, gas is released developing tremendous gas pressure within the fiber filament winding. This pressure causes the epoxy or other insulating material to fracture and the gas to escape to the inside of weathershed housing 58. Due to the flexible and resilient nature of elastomeric weathershed housing 58, the housing will expand, permitting the gas to flow along the length of the housing inner surface and out its axial ends. The gas can also vent between adjacent housings in a stacked arrangement, or through a spIit in the elastomeric housing.
Once the gas is released, the housing will contract and again tightly bear against assembly 52. Without this venting of the gas, the ga~ would be entrapped within the winding until the increasing gas pressure causes an explosion of the assembly. After venting, ionized gas causes an external arc bridging the damaged arrester to relieve the 'internal fault.
To mechanically and electrically connect a plurality of the electrical assemblies together in an .aligned, straight end-to-end serial array, externally threaded, metallic, and conductive studs can be used. These studs are advantageously substantially identical and interchangeable, as well as substantially rigid and formed' of stainless steel. The studs couple the adjacent ends of adjacent assemblies by being threadedly received in the threaded sockets in each assembly's adjacent end member. The adjacent ends of adjacent assemblies are screwed tightly together on the studs to provide a substantially gap-free engagement between the facing planar, axially-directed outer ends of the end members thereon. This provides an advantageous electrical and mechanical interface by reducing -possible separation during bending of the device. Plural weathershed housing 6ections, or a larger, one-piece housing can be used.
To provide sealing against water invasion, preferably a gasket 140 is interposed between each end member and the adjacent end plate, and silicone grease is interposed between each adjacent end plate and end member, between adjacent end members, and between the outer surfaces of the electrical assemblies and the inwardly facing surfaces of the throughbore in each weathershed housing section. ~se of grease between the weathershed housing section and the electrical assembly aids in construction and assembly by reducing friction and also reduces any radial gaps therebetween.
15Advantageously, the longitudinal axes of the studs, the electrical components in each assembly, and the weathershed housing 58 are coaxially aligned. Preferably, the planar ends of the end member6 are perpendicular to these aligned longitudinal axes.
- Preferably, with regard to the electrical device S0, the axial load on the electrical components before winding is about 750 pounds per square inch, and the filament or stranded element of fibers is wet, epoxy coated fiberglass -.; which is wound through about 100 turns and is cured for about two hours at 150C.
While a particular embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.
In the surge arresters of commonly assigned U.S. Patent No. 4,656,555 to Raudabaugh, copending Canadian patent application Serial No. 590,452 of Donald E. Raudabaugh entitled Polymer Housed Electrical Assemblies Using Modular Construction and filed February ~, 1989, and Canadian patent application Serial No. 587,515 filed January 4, 1989 entitled Modular Electrical Assemblies with Plastic Film sarriers of Donale E. Raudabaugh, resin soaked glass fibers completely surround and axially compress the varistor blocks. This complete enclosure of the varistor blocks may not~permit the gases generated upon varistor block failure to escape to the weathershed housing interior and then out of the weathershed housing before the gas pressure becomes too great and causes the assembly to break apart. If the 'SJs ~
filament wrap is relatively thin, the wrap can be burned through or can split before an extremely high pressure develops.
Summary of the Invention Accordingly, this invention seeks to provide electrical assemblies, particularly for surge arresters, which can vent gases generated upon electrical component failure to minimize damage, are relatively simple and inexpensive to manufacture, have good dielectric design, resist water invasion and have modular components and housings to simply vary voltage ratings.
Further the invention seeks to provide electrical assemblies, such as surge arresters, having high axial loadings, thereby resulting in uniform current distribution, low contact resistances at joints and excellent heat transfer to the arrester terminals.
Still further the invention seeks to provide an electrical assembly, such as a surge arrester, having a shatter-proof housing which has a high-impact strength and which does not fail in a dangerous fashion.
The invention in one aspect provides a modular electrical assembly, comprising a plurality of conductive electrical components, aligned in a column along an axis and having axially directed ends, the electrical components being electrically connected at the axially directed ends. First and second conductive end members are located at opposite ends of the column, each end member having a shoulder extending radially relative to the axis. A non-conductive winding is wrapped in a predetermined pattern longitudinally and crosswise about the electrical components and the end members, engaging the shoulders and applying an axially directed compressive force through tne shoulders on the electrical components and end members to maintain electrical connection therebetween. The winding has a first plurality of strand portions forming a first layer and a first opening therein and having a second plurality of strand portions forming a second layer and a second opening therein, the first and second openings having substantially the same shape and being substantially aligned to form a common -- opening for venting gas upon failure of one of the electrical components, the common opening extending completely through the winding radially relative to the axis.
Another aspect of the invention provides a surge arrester, comprising a plurality of generally cylindrical, metal oxide varistor blocks aligned in a column along an axis and having axially directed ends, the varistor blocks being in electrical connection with one another through the axially directed ends.
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, ,1 s 1334990 First and second generally cylindrical, conductive terminals are at opposite ends of each column, each terminal having a first axial end in contact with one of the varistor blocks and an opposite second axial end with an internally threaded socket, 5 the varistor blocks and the terminals having substantially equal transverse diameters. Compression means is wrapped longitudinally and crosswise around the varistor blocks and the ter~inals in a predetermined criss-cross pattern, for applying an axially-directed compressive force on the varistor blocks and the terminals to maintain electrical connection thereof, the compression means including a non-conductive filament winding having a first plurality of strand portions forming a first layer and first openings therein and a second plurality of strand portions forming a second layer and second openings therein. Respective first and second openings have substantially the same shape and are substantially aligned to form common preformed lateral openings in the winding for venting gas upon failure of one of the varistor blocks, the lateral openings completely through the winding radially relative to the axis. Elastomericl weathershed means, resiliently encloses the varistor blocks, for protecting the varistor blocks, the weathershed means having a substantially cylindrical throughbore with a diameter substantially equal to transverse diameters of the compression means.
Still further the invention provides an electrical surge arrester assembly, comprising a plurality of cylindrical surge arrester components arranged substantially coaxially to form a cylindrical stack of components having a longitudinal axis, the components having non-linear voltage-current characteristics and first and second electrically conductive terminals mounted at opposite respective ends of the stack and electrically coupled to the components, the terminals having radial surface portions substantially concentric with respect to the longitudinal axis.
A non-conductive tubular member encompasses the stack longitudinally and crosswise and has first and second opposite ends with radially projecting parts engaging and connected respectively to the first and second radial surface portions of the t,erminals, the tubular member having sufficient structural strength to apply an axially-directed compressive force by way of the terminals to the arrester components sufficient to maintain electrical contact between the components of the stack and the terminals. The tubular member is a winding having a first plurality of strand portions forming a first layer and a first opening therein and having a second plurality of strand 133~990 portions forming a second layer and a second opening therein, the first and second openings having substantially the same shape and being substantially aligned to form a common opening providing preformed venting means to facilitate lateral egress s therethrough of gaseous products produced by the stack. A
housing encompasses the tubular member and cooperates therewith to at least partially control the expulsion of the gaseous products from the assembly.
The invention still further provides a modular electrical assembly, comprising a plurality of conductive electrical components aligned in a row along an axis and has axially directed ends, at which they are electrically interconnected and at opposite ends of the row, there are first and second conductive end members. A non-conductive filament winding is wrapped longitudinally and crosswise about the electrical components and the end members and applies an axially directed compressive force on the electrical components and end members to maintain electrical connection therebetween. The winding has preformed lateral openings for venting gas upon failure of one of the electrical components, the lateral openings extending through the winding radially relative to the axis.
There is provided in a preferred aspect a modular electrical assembly including a plurality of conductive electrical components aligned in a row or column and electrically connected through their axially directed ends and a non-conductive fiber filament winding wrapped about the electrical components. The winding applies an axially directed compressive force on the electrical components to maintain their electrical connection and defines a pattern with lateral openings therein for venting gases generated upon failure of one of the electrical components.
Other aspects, advantages and salient features of the invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the invention.
Brief Description of the Drawings Referring to the drawings which form a part of this original disclosure:
Fig. 1 is a side elevational view in partial section of a modular electrical assembly in the form of a surge arrester, in accordance with the present invention, illustrating the outer surface of the filament winding;
Fig. 2 is a side elevational view in longitudinal section of the assembly illustrated in Fig. 1;
'-1'~ ~
` - :
- 5B - 133~990 Fig. 3 is an enlarged end elevational view in section taken along line 3 - 3 of Fig. 1;
Fig. 4 is an end elevational view of the end member of Figs. 1 and 2;
Fig. 5 is a side elevational view in section of the end member taken along line 5 - 5 of Fig. 4;
Fig. 6 is a side elevational view of the end member of Fig.` 4; and Figs. 7 - 9 are diagrammatic illustrations of the wrap pl'an for forming the pattern of the filament winding of Fig. 1.
Detailed Description of Preferred Embodiment Referring to Figs. 1 - 3, an electrical device 50, in the form of a surge arrester, according to the present invention is formed of a modular electrical assembly 52, enclosed in a polymeric, elastomeric weathershed housing 58.
The illustrated electrical assembly can be advantageously substantially identical to and interchangeable with the 1 33~ g90 other electrical assemblies, and is in turn formed from one or a plurality of cylindrical electrical components 60 and 62. These components are aligned in a row, and are in electrical connection with one another throush their axially-directed ends and under an axially-directed compressive force developed by a non-conductive filament winding 64, as disclosed in U.S. Patent No. 4,656,555 and ~anadian Serlal No. ~0,452. The electrical components can be metal oxide varistors (e.g. zinc oxide varistor blocks), `; resistors, capacitors or any combination thereof.
In the case of varistors used to form a surqe arrester, voltage ratings can be enlarged merely by serially and selectively coupling the plurality of modular electrical assemblies together mechanically and electrically.
The elastomeric weathershed housing S8 receives the electrical assemblies therein via a slight interference fit, ~his facilitates construction and allows the practice of good dielectric design by reducing radial gaps.
Electrical assembly 52 has a substantially cylindrical overall outer surface and comprises first end member, or terminal 72, spring washer 74, contact disc 76, electrical component 60, contact disc 78, electrical component 62, contact disc 80, spring washer 82, and second end member or terminal 84. Additional spring washers can be employed in the electrical assembly against the contact discs at some or all of the intermediate varistor joints, particularly for base mounted assemblies, to maintain contact pressure when the assembly bends under cantilever loading. ~he - non-cor.ductive filament winding 64 is coupled to end members 72 and 84, encloses the electrical components, and maintains them under an axially-directed force, which is augmented by the spring washers.
~ A plastic film barrier 110 laterally surrounding electrical components 60 and 62 is interposed coaxially between the electrical components and filament winding 64.
Preferably~ the plastic is polypropylene. The barrier 110 is formed by wrapping a rectangular plastic sheet tightly about 13~4990 the electrical components and the adjacent portions of end members 72 and 84 in pre~erably two layers before filament winding 64 is added. The thickness of the plastic sheet and of each layer is about 0.0005 inch.
Since the plastic film barrier extends along the entire length of the electrical components and onto the end members, the plastic film barrier seals the electrical components from the epoxy or resin on the filament forming the winding. For surge arresters, this prevents the wet epoxy or resin on the filament from bonding to the fragile ceramic insulating collars on the metal oxide varistor blocks 60 and 62. Such bonding can be prevented by other adhesion blockers, such as silicone oil or grease.
Advantageously, end members 72 and 84 are formed from aluminum. They can also be formed of any other material with suitable conductivity and mechanical strength.
End members 72 and 84 form internal terminals, have cylindrical exposed outer surfaces, and have opposite, first and second axially-directed planar ends with internally threaded sockets or bores 86 and 88 formed respectively therein. Socket 86 threadedly receives threaded end stud 90 which can be connected to an electrical power source and is in the form of a metallic, conductive bolt with an internally threaded nut 91. End plate 92 is received on end stud 90, tightly engages an end of the weathershed housing as seen in Figs. 1 and 2 and is held in place via rigid nut 91 on the stud. For base mounting, a base plate with a bolt circle can be attached. A second end plate 96 is similarly positioned at the other end of the housing and is received on end stud 98 which is connected to ground and maintained thereon via internally threaded nut 99 on the stud. Studs 90 and 98 in essence form external terminals for the overall device 50.
'Weathershed housing S8 has a through passageway in the form of a throughbore with an inwardly facing cylindrical surface 100 which tightly receives therein the outer cylindrical surface of the electrical assembly 52. The reception of the assembly in the throughbore is preferably -via an interference fit with the assembly having an outer surface diameter that $s about 2~ to about 9~ greater than the throughbore diameter and is substantially constant along its length. This reduces radial gaps and thus provides advantageous dielectric design.
Since end members 72 and 84 are identical, only end member 72 i8 described in detail. Referring particularly to Figs. 4-6 end member 72 comprises an inner section 120 and an outer section 122 separated by a radially extending flange 124. Inner section 120 is oriented adjacent the electrical components 60 and 62 and has a cylindrical lateral surface with a transverse diameter substantially equal to the electrical components. Inner section 120 defines that portion of the end member which receives film - 15 barrier 110. Outer section 122 also has a cylindrical lateral surface, but has a transverse diameter substantially less than inner section 120.
Flange 124 is generally circular in plan view and extends radially outwardly from the interface between sections 120 and 122. Radially inwardly extending and radially outwardly opening notches 126 are formed in the flange. Eight uniformally dimensioned notches are evenly and circumferentially spaced about flange 124 in the illustrated embodiment. The number of notches will vary depending upon the component diameter. More notches will be used w~th larger component diameters, and less notches will be used with smaller component diameters, The end members facilitate wrapping a non-conductive filament, e.g., glass in a pattern with diamond shaped lateral openings 128. Openings 128 are filled with a fracturable insulating material 130 having suitable insulating and mechanical characteristics, for example epoxy. Other suitable insulating materials include polyester, foam, rubber, silicone grease or gas, such as air. If the housing is molded about the electrical assembly wrap, the molded housing material can fill the openings.
The crisscross winding pattern illustrated in Fig. 1 is formed by wrapping one filament, or preferably a plurality of filaments simultaneously (typically 9) according to the pattern diagrammatlcally illustrated in Figs. 7-9 wherein the end member notches 126 are 6paced at 45 angl~es. The wrap plan used for a particular arrester will depend on component diameter, length and mechanical requirements. In these figures, end members 72 and 84 are denoted by the letters "L~ and "R" in Figs. 7 and 9, respectively. The individual notches 126 in each end member are numbered 1 through 8, respectively. In passing from end member to the other, the assembly i5 rotated through 180 as a filament is moved axially. Subsequently, the filament is rotated at the end member through an angle of 315 to the next notch position. This specific pattern illustrated is as follows and is illustrated in Fig. 8:
From To Rotation lL 5R 180 5L lR 180 lR 8R 315 iL 3L 315 2L lL 315 The pattern is repeated until the filament develops a thick~ess equal to the lateral peripheral extent of flange 124. Additional fiber filament is wound about the outer sections 122 until the filament surrounding such sections has a~ outer peripheral surface at least equal to the outermost extension of the flange. The outer surface of the assembly is then abraded to the extent necessary to provide a uniform cylindrical surface along its entire length.
r The insulating material 130 fills the openings 128 to maintain the desired uniform cylindrical surface of assembly 52. However, insulating material 130 can readily break or separate upon the development of adequate internal pressure within the winding, which pressure exceeds the' threshold level permitted by epoxy or other insulating material against rupture, to permit gas to vent.
Upon electrical component failure, gas is released developing tremendous gas pressure within the fiber filament winding. This pressure causes the epoxy or other insulating material to fracture and the gas to escape to the inside of weathershed housing 58. Due to the flexible and resilient nature of elastomeric weathershed housing 58, the housing will expand, permitting the gas to flow along the length of the housing inner surface and out its axial ends. The gas can also vent between adjacent housings in a stacked arrangement, or through a spIit in the elastomeric housing.
Once the gas is released, the housing will contract and again tightly bear against assembly 52. Without this venting of the gas, the ga~ would be entrapped within the winding until the increasing gas pressure causes an explosion of the assembly. After venting, ionized gas causes an external arc bridging the damaged arrester to relieve the 'internal fault.
To mechanically and electrically connect a plurality of the electrical assemblies together in an .aligned, straight end-to-end serial array, externally threaded, metallic, and conductive studs can be used. These studs are advantageously substantially identical and interchangeable, as well as substantially rigid and formed' of stainless steel. The studs couple the adjacent ends of adjacent assemblies by being threadedly received in the threaded sockets in each assembly's adjacent end member. The adjacent ends of adjacent assemblies are screwed tightly together on the studs to provide a substantially gap-free engagement between the facing planar, axially-directed outer ends of the end members thereon. This provides an advantageous electrical and mechanical interface by reducing -possible separation during bending of the device. Plural weathershed housing 6ections, or a larger, one-piece housing can be used.
To provide sealing against water invasion, preferably a gasket 140 is interposed between each end member and the adjacent end plate, and silicone grease is interposed between each adjacent end plate and end member, between adjacent end members, and between the outer surfaces of the electrical assemblies and the inwardly facing surfaces of the throughbore in each weathershed housing section. ~se of grease between the weathershed housing section and the electrical assembly aids in construction and assembly by reducing friction and also reduces any radial gaps therebetween.
15Advantageously, the longitudinal axes of the studs, the electrical components in each assembly, and the weathershed housing 58 are coaxially aligned. Preferably, the planar ends of the end member6 are perpendicular to these aligned longitudinal axes.
- Preferably, with regard to the electrical device S0, the axial load on the electrical components before winding is about 750 pounds per square inch, and the filament or stranded element of fibers is wet, epoxy coated fiberglass -.; which is wound through about 100 turns and is cured for about two hours at 150C.
While a particular embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.
Claims (55)
1. A modular electrical assembly, comprising:
a plurality of conductive electrical components, aligned in a column along an axis and having axially directed ends, said electrical components being electrically connected at said axially directed ends;
first and second conductive end members located at opposite ends of said column, each said end member having a shoulder extending radially relative to said axis; and a non-conductive winding wrapped in a predetermined pattern longitudinally and crosswise about said electrical components and said end members engaging said shoulders and applying an axially directed compressive force through said shoulders on said electrical components and end members to maintain electrical connection therebetween, said winding having a first plurality of strand portions forming a first layer and a first opening therein and having a second plurality of strand portions forming a second layer and a second opening therein, said first and second openings having substantially the same shape and being substantially aligned to form a common opening for venting gas upon failure of one of said electrical components, said common opening extending completely through said winding radially relative to said axis.
a plurality of conductive electrical components, aligned in a column along an axis and having axially directed ends, said electrical components being electrically connected at said axially directed ends;
first and second conductive end members located at opposite ends of said column, each said end member having a shoulder extending radially relative to said axis; and a non-conductive winding wrapped in a predetermined pattern longitudinally and crosswise about said electrical components and said end members engaging said shoulders and applying an axially directed compressive force through said shoulders on said electrical components and end members to maintain electrical connection therebetween, said winding having a first plurality of strand portions forming a first layer and a first opening therein and having a second plurality of strand portions forming a second layer and a second opening therein, said first and second openings having substantially the same shape and being substantially aligned to form a common opening for venting gas upon failure of one of said electrical components, said common opening extending completely through said winding radially relative to said axis.
2. A modular electrical assembly according to claim 1 wherein said openings are filled with fracturable insulating material.
3. A modular electrical assembly according to claim 2 wherein said fracturable insulating material is epoxy.
4. A modular electrical assembly according to claim 1 wherein an elastomeric housing coaxially surrounds and frictionally engages said winding.
5. A modular electrical assembly according to claim 4 wherein said housing has an internal throughbore forming an interference fit with said winding.
6. A modular electrical assembly according to claim 1 wherein a barrier laterally surrounds said electrical components and is interposed between said electrical components and said winding.
7. A modular electrical assembly according to claim 1 wherein said electrical components are varistors.
8. A modular electrical assembly according to claim 7 wherein said varistors are generally cylindrical metal oxide varistors.
9. A modular electrical assembly according to claim 1 wherein said winding extends over and surrounds at least a portion of each of said end members.
10. A modular electrical assembly according to claim 9 wherein said electrical components are generally cylindrical varistor blocks and said end members comprise cylindrical inner sections having substantially equal transverse diameters with said varistor blocks.
11. A modular electrical assembly according to claim 9 wherein each said shoulder comprises a radially extending flange on the respective end member with circumferentially spaced notches therein, said notches receiving portions of said winding to define said pattern, opening radially outwardly relative to said axis and extending through said flanges axially relative to said axis.
12. A modular electrical assembly according to claim 11 wherein each said end member comprises a reduced diameter section on a side of the flange thereof remote from said electrical components, said winding extending about said reduced diameter section to provide a substantially uniform transverse diameter along the entire axial length of the electrical assembly.
13. A modular electrical assembly according to claim 12 wherein each said reduced diameter section comprises an internally threaded bore.
14. A modular electrical assembly according to claim 1 wherein said openings are filled with insulating material.
15. A modular electrical assembly according to claim 14 wherein said insulating material is grease.
16. A surge arrester, comprising:
a plurality of generally cylindrical, metal oxide varistor blocks aligned in a column along an axis and having axially directed ends, said varistor blocks being in electrical connection with one another through said axially directed ends;
first and second generally cylindrical, conductive terminals at opposite ends of each said column, each said terminal having a first axial end in contact with one of said varistor blocks and an opposite second axial end with an internally threaded socket, said varistor blocks and said terminals having substantially equal transverse diameters;
compression means, wrapped longitudinally and crosswise around said varistor blocks and said terminals in a predetermined criss-cross pattern, for applying an axially-directed compressive force on said varistor blocks and said terminals to maintain electrical connection thereof, said compression means including a non-conductive filament winding having a first plurality of strand portions forming a first layer and first openings therein and a second plurality of strand portions forming a second layer and second openings therein, respective first and second openings having substantially the same shape and being substantially aligned to form common preformed lateral openings in said winding for venting gas upon failure of one of said varistor blocks, said lateral openings completely through said winding radially relative to said axis; and elastomeric weathershed means, resiliently enclosing said varistor blocks, for protecting said varistor blocks, said weathershed means having a substantially cylindrical throughbore with a diameter substantially equal to transverse diameters of said compression means.
a plurality of generally cylindrical, metal oxide varistor blocks aligned in a column along an axis and having axially directed ends, said varistor blocks being in electrical connection with one another through said axially directed ends;
first and second generally cylindrical, conductive terminals at opposite ends of each said column, each said terminal having a first axial end in contact with one of said varistor blocks and an opposite second axial end with an internally threaded socket, said varistor blocks and said terminals having substantially equal transverse diameters;
compression means, wrapped longitudinally and crosswise around said varistor blocks and said terminals in a predetermined criss-cross pattern, for applying an axially-directed compressive force on said varistor blocks and said terminals to maintain electrical connection thereof, said compression means including a non-conductive filament winding having a first plurality of strand portions forming a first layer and first openings therein and a second plurality of strand portions forming a second layer and second openings therein, respective first and second openings having substantially the same shape and being substantially aligned to form common preformed lateral openings in said winding for venting gas upon failure of one of said varistor blocks, said lateral openings completely through said winding radially relative to said axis; and elastomeric weathershed means, resiliently enclosing said varistor blocks, for protecting said varistor blocks, said weathershed means having a substantially cylindrical throughbore with a diameter substantially equal to transverse diameters of said compression means.
17. A surge arrester according to claim 16 wherein said openings are filled with insulating material.
18. A surge arrester according to claim 17 wherein said insulating material is fracturable epoxy.
19. A surge arrester according to claim 17 wherein said insulating material is grease.
20. A surge arrester according to claim 17 wherein said insulating material is fracturable.
21. An electrical surge arrester assembly, comprising:
a plurality of cylindrical surge arrester components arranged substantially coaxially to form a cylindrical stack of components having a longitudinal axis, said components having non-linear voltage-current characteristics;
first and second electrically conductive terminals mounted at opposite respective ends of said stack and electrically coupled to said components, said terminals having radial surface portions substantially concentric with respect to said longitudinal axis;
a non-conductive tubular member encompassing said stack longitudinally and crosswise and having first and second opposite ends with radially projecting parts engaging and connected respectively to said first and second radial surface portions of said terminals, said tubular member having sufficient structural strength to apply an axially-directed compressive force by way of said terminals to said arrester components sufficient to maintain electrical contact between said components of said stack and said terminals, said tubular member being a winding having a first plurality of strand portions forming a first layer and a first opening therein and having a second plurality of strand portions forming a second layer and a second opening therein, said first and second openings having substantially the same shape and being substantially aligned to form a common opening providing preformed venting means to facilitate lateral egress therethrough of gaseous products produced by said stack; and a housing encompassing said tubular member and cooperating therewith to at least partially control the expulsion of the gaseous products from the assembly.
a plurality of cylindrical surge arrester components arranged substantially coaxially to form a cylindrical stack of components having a longitudinal axis, said components having non-linear voltage-current characteristics;
first and second electrically conductive terminals mounted at opposite respective ends of said stack and electrically coupled to said components, said terminals having radial surface portions substantially concentric with respect to said longitudinal axis;
a non-conductive tubular member encompassing said stack longitudinally and crosswise and having first and second opposite ends with radially projecting parts engaging and connected respectively to said first and second radial surface portions of said terminals, said tubular member having sufficient structural strength to apply an axially-directed compressive force by way of said terminals to said arrester components sufficient to maintain electrical contact between said components of said stack and said terminals, said tubular member being a winding having a first plurality of strand portions forming a first layer and a first opening therein and having a second plurality of strand portions forming a second layer and a second opening therein, said first and second openings having substantially the same shape and being substantially aligned to form a common opening providing preformed venting means to facilitate lateral egress therethrough of gaseous products produced by said stack; and a housing encompassing said tubular member and cooperating therewith to at least partially control the expulsion of the gaseous products from the assembly.
22. The assembly according to claim 21, wherein said housing is resilient.
23. The assembly according to claim 22, wherein said tubular member is rigid against bending in directions transverse to said longitudinal axis and further wherein said housing is supported against bending by said tubular member.
24. The assembly of claim 21, wherein said housing is resilient and is molded on said tubular member with portions of said housing filling said openings.
25. The assembly according to claim 21, wherein said tubular member is composed of filamentary material.
26. The assembly according to claim 25, wherein said openings are diamond shaped.
27. The assembly according to claim 25, wherein said filamentary material is comprised of a continuous strand wound a plurality of times to form a generally criss-cross pattern in said member.
28. The assembly according to claim 27, wherein the opening is substantially diamond-shaped.
29. The assembly according to claim 28, wherein the opening is filled with a fracturable insulating material.
30. The assembly according to claim 23, wherein said housing encompasses at least part of said terminals and encompasses said stack with an interference fit.
31. A modular electrical assembly, comprising:
a plurality of conductive electrical components aligned in a row along an axis and having axially directed ends, at which they are electrically interconnected;
at opposite ends of said row, first and second conductive end members; and a non-conductive filament winding wrapped longitudinally and crosswise about said electrical components and said end members and applying an axially directed compressive force on said electrical components and end members to maintain electrical connection therebetween, characterized in that said winding has preformed lateral openings for venting gas upon failure of one of said electrical components, said lateral openings extending through said winding radially relative to said axis.
a plurality of conductive electrical components aligned in a row along an axis and having axially directed ends, at which they are electrically interconnected;
at opposite ends of said row, first and second conductive end members; and a non-conductive filament winding wrapped longitudinally and crosswise about said electrical components and said end members and applying an axially directed compressive force on said electrical components and end members to maintain electrical connection therebetween, characterized in that said winding has preformed lateral openings for venting gas upon failure of one of said electrical components, said lateral openings extending through said winding radially relative to said axis.
32. A modular electrical assembly according to claim 31, wherein said openings are filled with fracturable insulating material.
33. A modular electrical assembly according to claim 32, wherein said insulating material is an epoxy resin or a grease.
34. A modular electrical assembly according to claim 31, wherein an elastomeric housing coaxially surrounds and frictionally engages said filament winding.
35. A modular electrical assembly according to claim 34, wherein said housing has an internal throughbore forming an interference fit with the filament winding.
36. A modular electrical assembly according to claim 31, wherein a barrier laterally surrounds said electrical components and is interposed between the electrical components and the filament winding.
37. A modular electrical assembly according to claim 31, wherein each said flange on the respective end member has circumferentially spaced notches therein, said notches receiving portions of said filament winding to define a predetermined pattern, opening radially outwardly relative to said axis and extending through said flanges axially relative to said axis.
38. A modular electrical assembly according to claim 37, wherein each said end member comprises a reduced diameter section (122) on a side of the flange thereof remote from said electrical components (62), said filament winding (64) extending about said reduced diameter section (122) to provide a substantially uniform transverse diameter along the entire axial length of the electrical assembly.
39. A modular electrical assembly according to claim 38, wherein each said reduced diameter section (122) comprises an internally threaded bore (86).
40. A modular electrical assembly according to claim 31, 32, 33, 34, 35, 36, 37, 38 or 39, wherein said pattern of the winding is a criss-cross pattern and said lateral openings (28) are generally diamond-shaped.
41. A modular electrical assembly according to claim 31, 32, 33, 34, 35, 36, 37, 38 or 39, wherein said openings (28) are discrete and longitudinally segmented.
42. A modular electrical assembly according to claim 31, 32, 33, 34, 35, 36, 37, 38 or 39, wherein said filament winding was wrapped about said electrical components and said end members while said electrical components and said end members were axially compressed.
43. A modular electrical assembly according to claim 31, 32, 33, 34, 35, 36, 37, 38 or 39, wherein said electrical components (62) are varistors and the assembly functions as a surge arrestor.
44. A modular electrical assembly according to claim 31, 32, 33, 34, 35, 36, 37, 38 or 39, wherein said electrical components (62) are generally cylindrical metal oxide varistors and the assembly functions as a surge arrestor.
45. A modular electrical assembly according to claim 31, 32, 33, 34, 35, 36, 37, 38 or 39, wherein said electrical components (62) are generally cylindrical block varistors and said end members (72) comprise cylindrical inner sections having substantially equal transverse diameters with said varistor blocks.
46. A modular electrical assembly, comprising:
a plurality of conductive electrical components aligned in a column along an axis and having axially directed ends, said electrical components being electrically connected at said axially directed ends;
first and second conductive end members located at opposite ends of said column, said end members having shoulders extending radially relative to said axis;
a non-conductive filament winding wrapped in a predetermined pattern about said electrical components and said end members engaging said shoulders and applying an axially directed compressive force through said shoulders on said electrical components and end members to maintain electrical connection therebetween, said winding having a first plurality of strand portions forming a first layer and first openings therein and a second plurality of strand portions forming a second layer and second openings therein, respective first and second openings having substantially the same shape and being substantially aligned to form common lateral openings in said winding for venting gas upon failure of one of said electrical components, said lateral openings extending completely through said winding radially relative to said axis; and fracturable insulating material filling said openings.
a plurality of conductive electrical components aligned in a column along an axis and having axially directed ends, said electrical components being electrically connected at said axially directed ends;
first and second conductive end members located at opposite ends of said column, said end members having shoulders extending radially relative to said axis;
a non-conductive filament winding wrapped in a predetermined pattern about said electrical components and said end members engaging said shoulders and applying an axially directed compressive force through said shoulders on said electrical components and end members to maintain electrical connection therebetween, said winding having a first plurality of strand portions forming a first layer and first openings therein and a second plurality of strand portions forming a second layer and second openings therein, respective first and second openings having substantially the same shape and being substantially aligned to form common lateral openings in said winding for venting gas upon failure of one of said electrical components, said lateral openings extending completely through said winding radially relative to said axis; and fracturable insulating material filling said openings.
47. A modular electrical assembly according to claim 46 wherein said fracturable insulating material is epoxy.
48. A modular electrical assembly according to claim 46 wherein an elastomeric housing coaxially surrounds and fractionally engages said filament winding.
49. A modular electrical assembly according to claim 48 wherein said housing has an internal throughbore forming an interference fit with said filament winding.
50. A modular electrical assembly according to claim 46 wherein said electrical components are varistors.
51. A modular electrical assembly according to claim 50 wherein said varistors are generally cylindrical metal oxide varistors.
52. A modular electrical assembly according to claim 46 wherein said pattern is a criss-cross pattern and said lateral openings are generally diamond shaped.
53. A modular electrical assembly according to claim 1 wherein an elastomeric housing is molded about said winding, with portions thereof filling said openings.
54. A surge arrester according to claim 16 wherein portions of said elastomeric weathershed means fill said openings.
55. A modular electrical assembly according to claim 31 wherein an elastomeric housing is molded about said winding, with portions thereof filling said openings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000616936A CA1339484C (en) | 1988-03-31 | 1994-10-18 | Modular electrical assemblies with pressure relief |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US17631788A | 1988-03-31 | 1988-03-31 | |
| US176,317 | 1988-03-31 |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000616936A Division CA1339484C (en) | 1988-03-31 | 1994-10-18 | Modular electrical assemblies with pressure relief |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1334990C true CA1334990C (en) | 1995-03-28 |
Family
ID=22643877
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000587516A Expired - Lifetime CA1334990C (en) | 1988-03-31 | 1989-01-04 | Modular electrical assemblies with pressure relief |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0335480B1 (en) |
| JP (1) | JP2520467B2 (en) |
| AR (1) | AR241834A1 (en) |
| CA (1) | CA1334990C (en) |
| DE (1) | DE68903979T2 (en) |
| MX (1) | MX172867B (en) |
| YU (1) | YU47606B (en) |
| ZA (1) | ZA891167B (en) |
Families Citing this family (23)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4930039A (en) * | 1989-04-18 | 1990-05-29 | Cooper Industries, Inc. | Fail-safe surge arrester |
| SE469247B (en) * | 1991-10-04 | 1993-06-07 | Asea Brown Boveri | surge |
| US5363266A (en) * | 1992-06-18 | 1994-11-08 | Raychem Corporation | Electrical surge arrester |
| DE4306691A1 (en) * | 1993-03-04 | 1994-11-03 | Abb Management Ag | Surge arresters |
| JP2888754B2 (en) * | 1993-05-31 | 1999-05-10 | フェニックス、コンタクト、ゲゼルシャフト、ミット、ベシュレンクテル、ハフツング、ウント、コンパニー | Overvoltage protection device |
| SE516123C2 (en) * | 1994-05-13 | 2001-11-19 | Abb Ab | Valve diverter, method of making such and use |
| DE19622140A1 (en) * | 1996-06-01 | 1997-12-04 | Asea Brown Boveri | Surge arresters |
| US5712757A (en) * | 1996-06-27 | 1998-01-27 | Raychem Corporation | Surge arrester having ridged terminals |
| US5757604A (en) * | 1996-06-27 | 1998-05-26 | Raychem Corporation | Surge arrester having grooved and ridged terminals |
| FR2757693B1 (en) * | 1996-12-23 | 1999-02-19 | Sediver | SURGE PROTECTOR WITH ENVELOPE HAVING EMBOSSED OUTER SURFACE |
| ES1036799Y (en) * | 1997-03-26 | 1998-04-01 | Ind De Aparellaje Electrico S | SURGE VOLTAGE UNLOADER. |
| JP2001028303A (en) * | 1999-07-15 | 2001-01-30 | Toshiba Corp | Voltage nonlinear resistor unit and lightning arrester unit |
| DE10136617C1 (en) * | 2001-07-17 | 2002-10-10 | Siemens Ag | Surge arrester for use in power transmission networks comprises several varistor blocks which have coating which initiates arc-over when its temperature exceeds preset value |
| KR100445079B1 (en) * | 2002-04-16 | 2004-08-21 | 한국전기연구원 | Method for manufacturing module of polymeric arrester by multispindle filament winding |
| RU2222842C1 (en) * | 2002-07-01 | 2004-01-27 | Научное конструкторско-технологическое бюро "Пьезоприбор" Ростовского государственного университета | Solid state protector |
| KR100714991B1 (en) * | 2005-04-15 | 2007-05-09 | 강영길 | Polymer lightning arrester module tube and method of manufacturing polymer arrester module using the tube |
| JP5301320B2 (en) * | 2009-03-02 | 2013-09-25 | 三菱電機株式会社 | Lightning arrestor |
| DE102011009124A1 (en) * | 2011-01-21 | 2012-07-26 | Tridelta Überspannungsableiter Gmbh | Surge arrester with cage design |
| EP3057109A1 (en) * | 2015-02-12 | 2016-08-17 | Siemens Aktiengesellschaft | Surge arrester |
| CN105097153B (en) * | 2015-09-11 | 2018-04-13 | 南阳金冠电气有限公司 | A kind of compound arrester core group winding arrangement |
| WO2021168585A1 (en) | 2020-02-26 | 2021-09-02 | 10551554 Canada Inc. D/B/A Armada Surge Protection | Power surge protector |
| DE102020133830B3 (en) * | 2020-12-16 | 2022-03-31 | TRIDELTA Meidensha GmbH | Surge arrester with coil design and method for its manufacture |
| CN113130148A (en) * | 2021-04-02 | 2021-07-16 | 句容市凯特电力电器有限公司 | Rigid suspension stain-resistant umbrella skirt-shaped porcelain insulator |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3283196A (en) * | 1965-02-04 | 1966-11-01 | Westinghouse Electric Corp | Expulsion lightning arrester |
| DE3001943A1 (en) * | 1980-01-21 | 1981-07-23 | Boris Konstantinovič Avdeenko | Surge voltage arrester - with gas duct in insulated tube parallel to nonlinear resistor stack |
| US4467387A (en) * | 1982-09-30 | 1984-08-21 | General Electric Company | Combination strut insulator and lightning arrester |
| US4656555A (en) * | 1984-12-14 | 1987-04-07 | Harvey Hubbell Incorporated | Filament wrapped electrical assemblies and method of making same |
| JPH0773084B2 (en) * | 1986-06-06 | 1995-08-02 | 音羽電機工業株式会社 | Lightning arrester |
-
1989
- 1989-01-04 CA CA000587516A patent/CA1334990C/en not_active Expired - Lifetime
- 1989-01-24 DE DE8989300653T patent/DE68903979T2/en not_active Expired - Lifetime
- 1989-01-24 EP EP89300653A patent/EP0335480B1/en not_active Expired - Lifetime
- 1989-01-25 MX MX014654A patent/MX172867B/en unknown
- 1989-01-25 JP JP1016094A patent/JP2520467B2/en not_active Expired - Fee Related
- 1989-02-08 YU YU29289A patent/YU47606B/en unknown
- 1989-02-15 ZA ZA891167A patent/ZA891167B/en unknown
- 1989-03-27 AR AR89313498A patent/AR241834A1/en active
Also Published As
| Publication number | Publication date |
|---|---|
| EP0335480B1 (en) | 1992-12-23 |
| JP2520467B2 (en) | 1996-07-31 |
| DE68903979T2 (en) | 1993-05-13 |
| DE68903979D1 (en) | 1993-02-04 |
| YU29289A (en) | 1993-05-28 |
| MX172867B (en) | 1994-01-18 |
| EP0335480A3 (en) | 1990-01-31 |
| EP0335480A2 (en) | 1989-10-04 |
| YU47606B (en) | 1995-10-24 |
| JPH01255437A (en) | 1989-10-12 |
| ZA891167B (en) | 1990-04-25 |
| AR241834A1 (en) | 1992-12-30 |
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