CA1334300C

CA1334300C - Polymer housed electrical assemblies using modular construction

Info

Publication number: CA1334300C
Application number: CA 590452
Authority: CA
Inventors: Donald E. Raudabaugh
Original assignee: Hubbell Inc
Current assignee: Hubbell Inc
Priority date: 1988-12-02
Filing date: 1989-02-08
Publication date: 1995-02-07
Anticipated expiration: 2012-02-07

Abstract

An electrical device comprising a plurality of electrical assemblies formed as interchangeable modules, aligned in an end-to-end serial array and enclosed in a polymeric weathershed housing, the electrical assemblies being electrically and mechanically coupled together. Each electrical assembly in turn comprises 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 nonconductive filament winding. The electrical components can be varistors, resistors, capacitors, and insulators or any combination thereof. In the case of varistors used to form a surge arrester, for example, voltage ratings can be enlarged merely by serially coupling a plurality of separately wrapped electrical components in the form of MOV
blocks. Enclosing the electrical assemblies is a weathershed housing, which tightly receives the assemblies therein and which facilitates construction and allows the practice of good dielectric design.

Description

` 1 334300 POLYMER HOUSED ELECTRICAL ASSEM~LIES
USING MODULAR CONSTRUCTION

Related Applications This application is related to Canadian 5application Serial No. 488,845 filed August 16, 1985.

Field of the Invention The invention relates to polymer housed electrical assemblies which are formed as modules and which are selectively coupled together to vary the overall electrical rating of the device. Each electrical assembly is formed from electrical components that are wrapped in a nonconductive filament winding. The components can be varistors, resistors, capacitors, insulators, or any combination thereof.

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- 2 - 1 3343DO

Backqround 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 sur~es 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 bloc~s 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, abo~t sixty pounds. As a result, prior art surge 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 is produced can cause axial flashover at high currents.
An additional pro~lem with surge arresters of the prior art i~ that they, on rare occasions, fail in a dangerous fashion. When these arresters fail and experience high fault currents, the bursting unit may throw parts and cause property damage. --.,:, .

_ 3 _ 1 334300 ~_ 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 Kaczerginski; 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 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.
Summary of the Invention Accordingly, the invention seeks to provide electrical devices, particularly surge arresters, which are relatively simple to assemble, 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.
Further still the invention seeks to provide an MOV block assembly with greatly improved tensile and cantilever strengths.
Further still the invention seeks to provide a surge arrester which i8 forgiving of dimensional variations in associated parts, thereby reducing the need for expensive close tolerances.
Briefly the inve~tion pertains to an electrical device, the combination comprising a plurality of electrical assemblies, each having first and second ends and substantially cylindrical outer surfaces with substantially similar diameters, the assemblies being oriented in an end-to-end serial array, a connector, coupled to each pair of adjacent electrical ,~i _ 4 _ 1 3 34 3 ~0 assemblies, for electrically and mechanically coupling each adjacent pair of electrical assemblies, a weathershed housing, enclosing the assemblies, for protecting the assemblies, the weathershed housing having a substantially cylindrical throughbore with substantially the same diameter as the diameters of each of the electrical assemblies' outer surfaces and terminals, coupled to each of the two electrical assemblies at opposite ends of the serial array.
More particularly, the invention in one broad aspect provides an electrical device, the combination comprising a plurality of conductive electrical assemblies, each electrical assembly having first and second ends and substantially cylindrical outer surfaces with substantially similar diameters, the assemblies being oriented in an end-to-end serial array.
lS Means i8 coupled to each pair of adjacent electrical assemblies, for electrically and mechanically coupling each adjacent pair of electrical assemblies, the mechanical coupling resisting relative axial movement between the electrical assemblies.
Weathershed means completely encloses the assemblies and the means for electrically and mechanically coupling and protects the assemblies and the means for electrically and mechanically coupling. The weathershed means has a substantially cylindrical throughbore with substantially the same diameter as the diameters of each of the electrical assemblies outer surfaces.
2S Terminal means, coupled to each of the two electrical assemblies is at opposite ends of the serial array.
Another aspect of the invention provides an electrical device in combination comprising a plurality of conductive electrical assemblies, each electrical assembly having first and second ends, the assemblies being oriented in an end-to-end serial array and means, coupled to each pair of adjacent electrical assemblies, for electrically and mechanically coupling each adjacent pair of electrical assemblies, the mechanical coupling resisting relative axial movement between the electrical asse~blies. Weathershed means, completely encloses the assemblies and the means for electrically and mechanically coupling, protects the assemblies and the means for electrically and mechanically coupling and terminal means is coupled to each of the two electrical assemblies at opposite ends of the serial array. Each of the electrical assemblies includes a plurality of conductive electrical components aligned in a row and having axially-directed ends, the electrical components being in electrical connection with one another via the axially-directed ends. Means is wrapped around the components, for applying an axially-directed compressive force on the plurality of electrical components to maintain the electrical connection thereof and the means for applying an axially-directed compressive force includes a non-conductive filament winding.
Still another aspect of the invention provides a modular electrical assembly, in combination comprising a plurality of conductive electrical components aligned in a row, the electrical components having axially-directed ends and being in electrical connection via their axially-directed ends. A first electrically conductive terminal is located at a first end of the row, the first terminal having first and second axially-directed ends and being in electrical connection with the electrical components via the first axially-directed end thereof and having an axially-directed surface facing in a direction opposite the first axially-directed end thereof. A second electrically conductive terminal is located at a second end of the row, the second terminal having first and second axially-directed ends and being in electrical connection with the electrical components via the first axially-directed end thereof and having an axially-directed surface facing in a direction opposite the first axially-directed end thereof. Connecting means is in the second end of at least one of the terminals, for electrically and mechanically coupling the one terminal to an adjacent, similarly constructed modular electrical assembly, the mechanical coupling resisting relative axial movement between - coupled modular electrical assemblies. Compression means, coupled to the first and second terminals, axially compresses the electrical components and the first and second terminals together as a unit,~ the compression means comprising a non-conductive filament winding enclosing and axially compressing the electrical components and engaging the axially-directed surfaces.
Further still, there is provided an electrical device, in combination comprising a plurality of substantially identical and interchangeable modular conductive electrical assemblies in an end-to-end serial array, the electrical assemblies each having a substantially cylindrical lateral outer surface with substantially similar diameter. Each electrical assembly has first and second terminals at opposite ends thereof and weathershed means, completely encloses the lateral outer surfaces of the electrical assemblies for protecting the electrical assemblies. First means is coupled to adjacent pairs of terminals for internally electrically and mechanically J_ -- 4~ -coupling adjacent electrical assemblies, the mechanical coupling resisting relative axial movement between the electrical assemblies. Second means is coupled to the two terminals at opposite ends of the serial array for establishing an external electrical and mechanical connection of the device. The weathershed means also completely encloses the lateral outer surface of the first means for protecting the first means and it has a substantially cylindrical throughbore of a diameter corresponding to the diameters of each of the electrical assemblies outer surfaces.
A still further aspect of the invention provides a surge arrester, comprising a modular unit having a plurality of substantially cylindrical metal oxide varistor blocks with opposite, substantially planar ends, the blocks being substantially axially aligned and in end-to-end electrically conductive relationship forming a substantially cylindrical block stack of desired electrical surge arresting characteristics and having a stack length. First and second substantially cylindrical, conductive terminals are at opposite ends of the stack and have axially-directed surfaces facing in directions opposite to the stack. Electrically non-conductive stack loading means, extending along the stack length and circumferentially around all of the blocks and engaging the axially-directed surfaces on the terminals, axially compresses the stack and maintains electrical contact between the blocks.
The loading means encloses the block stack therein and forms a ~ generally cylindrical, non-conductive cover over the block stack having an outer diameter. An elongated housing of elastomeric material, having an axial, substantially cylindrical, interior bore opening at opposite ends thereof, receives the block stack enclosed in the cover through one of the ends of the housing, the bore defining an inner diameter of the housing relative to the outer diameter of the cover for providing close fit therebetween for minimizing gaps between the cover and the housing.
Still further, the invention provides a surge arrester assembly, comprising a modular unit including a plurality of substantially cylindrical metal oxide varistor blocks of substantially equal diameter with opposite, substantially planar ends, the blocks being axially aligned in end-to-end contact forming a substantially cylindrical block stack with desired electrical surge arresting characteristics. First and second substantially cylindrical, conductive terminals are at opposite ends of the block stack and have axially-directed surfaces L

~ 33~300 facing in directions opposite to the block stack. The unit further includes an elongated, electrically non-conductive element having a substantially cylindrical outer surface, which encloses the block stack, the element comprising a plurality of axially disposed filament windings coupled to the axially directed surfaces of the terminals and extending the length of the stack for applying an axially-directed compressive force to the blocks to hold the blocks and terminals in end-to-end contact. There is a resilient housing having opposite ends and a substantially cylindrical, interior bore opening at one end of the housing, the bore being accessible for axial entry of the modular unit into the one end of the housing. The bore has a diameter relative to the outer diameter of the element, whereby the element forms a close fit with the bore for reducing gaps between the unit and the housing.
The invention in a still further aspect provides a surge arrester assembly for protecting electrical circuits, comprising a plurality of substantially cylindrical blocks having non-linear voltage-current characteristics of substantially equal diameter with opposite, substantially planar ends, the blocks being axially aligned in end-to-end relationship to form a substantially coaxial block stack. ~irst and second electrically conductive terminal members are disposed at opposite respective ends of the block stack in adjacency with different ones of the blocks located at the opposite respective ends of the stack, the terminal members having axially facing ~ surfaces. An elastomeric housing has opposite ends and an axial, interior bore and non-conductive filament winding means at least partially encloses the blocks and engages the surfaces of the terminal members. The winding means applies an axially-directed compressive force to the blocks and the terminal members, the means applying the force independently of the housing to maintain axial electrical contact between the blocks and the terminal members with the means, the blocks and the terminal members being received in the bore of the housing.
Still further, there is provided a surge arrester assembly for protecting an electrical circuit, comprising a plurality of substantially cylindrical blocks having non-linear voltage-current characteristics of substantially e~ual diameter with opposite, substantially planar ends, the blocks being axially aligned to form a substantially cylindrical block stack and first and second axially aligned, electrically conductive, terminal members are disposed at opposite respective ends of the block stack in adjacency with different ones of the blocks 1 3343~0 - 4~ _ located at the opposite respective ends of the stack. There is an elongated housing comprised of a polymeric electrical insulation having opposite ends and a longitudinal cylindrical bore intermediate the opposite ends. Elongate, non-conductive filament winding means is coupled to the terminal members, for applying and maintaining an axially-directed compressive force to the blocks by way of the terminal members, the non-conductive filament winding means having a substantially smooth and cylindrical outer surface, whereby the non-conductive filament winding means, blocks and terminal members form a substantially right circular cylindrical module of axially compressed blocks and terminal members of substantially constant diameter along the entire length of the module. The module is mounted in the bore of the housing with a close fit with portions of the terminal members being accessible from opposite respective ends of the housing for connection to the electrical circuit, whereby the module maintains the compressive force on the blocks and terminal members independently of the housing. An adhesive may be applied to the winding means for rendering the module rigid.
The invention also comprehends a surge arrester comprising a plurality of substantially cylindrical blocks having non-linear voltage-current characteristics of substantially equal diameter with opposite, substantially planar ends, the blocks being axially aligned in end-to-end relationship to form a substantially coaxial block stack. First and second - electrically conductive terminals are disposed at opposite respective ends of the block stack adjacent different ones of the blocks located at the opposite respective ends of the stack.
Non-conductive filament winding means at least partially encloses the blocks and terminals for applying an axially-directed compressive force to the blocks and the terminals. A
housing has open opposite ends, an axial interior throughbore and a plurality of weathersheds thereon, each of the weathersheds having substantially the same outer diameter and root diameter with the blocks and terminals being received in the housing. There is a pair of disc-shaped end plates, each of the end plates abutting one of the housing opposite ends and having an outer diameter greater than the root diameter of the weathersheds.
Further still, the invention provides a surge arrester comprising first and second electrically conductive terminals and at least one non-linear resisting block having first and second axially-directed ends and positioned between the first .~. ~, f ,,, and second terminals to form a substantially cylindrical structure having a substantially uniform circumferential outer surface. The first terminal has an axially-directed end thereon in electrical connection with the first axially-directed end of the block and includes a first surface facing in an axial direction opposite the axially-directed end thereof. The second terminal has an axially-directed end thereon in electrical connection with the second axially-directed end of the block and includes a second surface facing in an axial direction opposite 0 the axially-directed~ end thereof. A plurality of discrete elongated tensile elements formed of an insulating material and spaced circumferentially around and extending adjacent one another the length of the outer surface engages the first and second surfaces of the first and second terminals, the tensile elements being under axial tension to thereby apply an axially-directed compression force to the first and second terminals and the block, whereby transverse bending of the arrester is resisted and the first and second terminals and the block are maintained in electrical connection. A housing having a cylindrical bore with an inwardly facing substantially cylindrical surface closely encloses the block, terminals and tensile elements therein.
Further still, the invention comprehends a surge arrester comprising first and second electrically conductive terminals, at least one non-linear resistive block, having first and second axially-directed ends and a substantially cylindrical outer surface, positioned between the first and second terminals and a plurality of elongated tensile elements formed of an insulating material positioned around the block at circumferentially spaced locations. The first terminal has an axially-directed end thereon in electrical connection with the first axially-directed end of the block, the first terminal including a first surface for engaging the tensile elements.
The second terminal has an axially-directed end thereon in electrical connection with the second axially-directed end of the block, the second terminal including a second surface for engaging the tensile elements. The tensile elements engage the first and second surfaces and are axially tensioned to thereby apply an axially-directed compression force to the first and second surfaces and the block to resist transverse bending of the arrester and to maintain the first and second terminals and the block in electrical connection. A housing having a through passageway with an inwardly facing substantially cylindrical surface has a diameter substantially equal to the diameter of - 4F - ~ 334300 thé block outer surface with the tensile elements positioned therearound and receives the block and elements therein.
The invention also comprehends a surge arrester, comprising a modular unit having a plurality of substantially cylindrical metal oxide varistor~blocks with opposite, substantially planar ends, the blocks being substantially axially aligned and in end-to-end electrically conductive relationship forming a substantially cylindrical block stack of desired electrical surge arresting characteristics and having a stack length.
First and second substantially cylindrical, conductive terminals are at opposite ends of the block stack and have axially directed surfaces facing in directions opposite to the block stack. Electrically non-conductive stack loading means extend along the stack length and circumferentially around all of the blocks and engage the axially directed surfaces of the terminals for axially compressing the stack and for maintaining electrical contact between the blocks. The loading means encloses the block stack therein and forms a generally cylindrical, non-conductive cover over the block stack having an outer diameter whereby transverse bending is resisted. An elongated housing of elastomeric material has an axial, substantially cylindrical, interior bore opening at opposite ends thereof for axial entry of electrical currents to the block stack enclosed in the cover through one of the ends of the housing, the bore defining an inner diameter of the housing which is such as to provide a closely adjacent fit between the housing and the cover and thereby minimize gaps between the cover and the housing.
Further still, the invention provides a surge arrester assembly for protecting an electrical circuit, comprising a plurality of substantially cylindrical blocks having non-linear voltage-current characteristics of substantially equal diameter with opposite, substantially planar ends, the blocks being axially aligned to form a substantially cylindrical block stack.
First and second axially aligned, electrically conductive, terminal members are disposed at opposite respective ends of the block stack in adjacency with different ones of the blocks having axial ends located at the opposite respective ends of the stack and axially directed surfaces facing in an axial direction opposite the ends of the blocks. An elongated housing comprised of a polymeric electrical insulation has opposite ends and a longitudinal cylindrical bore intermediate the opposite ends.
Elongate, non-conductive filamentary wrap means is coupled to the axially-directed surfaces of the terminal members and applies and maintains an axially-directed compressive force to - 4G - 1 ~343~
the blocks by way of~the terminal members, the non-conductive filament wrap means having a substantially smooth and cylindrical outer surface and being sufficiently rigid whereby the wrap means, blocks and terminal members form a rigid, substantially cylindrical module of axially compressed blocks and terminal members resistant to transverse bending. The module is mounted in the bore of the housing with a closely adjacent fit with portions of the terminals accessible from opposite respective ends of the housing for connection to the electrical circuit, whereby the module maintains the compressive force on the blocks and terminal members independently of the housing.
Further still, there is provided a surge arrester comprising a plurality of substantially cylindrical blocks having non-linear voltage-current characteristics of substantially equal diameter with opposite, substantially planar ends, the blocks being axially aligned in end-to-end relationship to form a substantially coaxial block stack, first and second electrically conductive terminals are disposed at opposite respective ends of the block stack adjacent different ones of the blocks located at the opposite respective ends of the stack. Non-conductive filamentary wrapping, at least partially encloses the blocks and terminals for applying an axially-directed compressive force to the blocks and the terminals. A housing has open opposite ends, an axial interior bore and a plurality of weathersheds thereon, each of the weathersheds having substantially the same outer diameter and root diameter with the blocks and terminals being received in the housing. There is a pair of disc-shaped end plates, each of the end plates abutting one of the housing opposite ends and having an outer diameter greater than the root diameter of the weathersheds.
Another aspect of the invention provides an electrical device wherein the combination comprises a plurality of conductive electrical assemblies, each electrical assembly having first and second ends, the assemblies being oriented in an end-to-end serial array with means coupled to each pair of adjacent electrical assemblies, for electrically and mechanically coupling each adjacent pair of electrical assemblies, the mechanical coupling resisting relative axial movement between the electrical assemblies. Weathershed means completely encloses lateral outer surfaces of the assemblies and the means for electrically and mechanically coupling, for protecting the assemblies and the means for electrically and - 4H - l 334300 mechanically coupling. Terminal means is coupled to each of the two electrical assemblies at opposite ends of the serial array.
Each of the electrical assemblies includes a plurality of conductive electrical components aligned in a row and having axially-directed ends, the electrical components being in electrical connection with one another via the axially-directed ends. Non-conductive means is wrapped around the components for applying an axially-directed, compressive force on the plurality of electrical components to maintain the electrical connection thereof, the means for applying an axially-directed, compressive force including filamentary material which also resists transverse bending of the device.
Still another aspect of the invention provides a surge arrester wherein the combination includes at least one non-linear resistive block having first and second axially-directed ends. A first electrically conductive terminal has an axially directed end thereon in electrical connection with the first axially-directed end of the block and further has an axially-directed surface thereon facing in a direction opposite the axially-directed end thereof. A second electrically conductive terminal has an axially directed end thereon in electrical connection with the second axially-directed end of the block and has an axially-directed surface thereon facing in a direction opposite the axially-directed end thereof. A non-conductive filament is wrapped around the block and wrapped around and engages the axially-directed surfaces on the terminals, the filament being axially tensioned to thereby apply an axially-directed compression force to the terminals and the block to resist transverse bending of the arrester and to maintain the terminals and block in electrical connection.
A still further aspect of the invention provides a surge arrestor, comprising a plurality of generally cylindrical, metal oxide varistor blocks aligned in a row along an axis and having axially directed ends, the varistor blocks being in electrical connection with one another through the axially directed ends.
First and second generally cylindrical conductive terminals are at opposite ends of the row, 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. The terminals have inner sections adjacent the first axial ends and outer sections adjacent the second axial ends, the inner sections being narrower than the outer sections. The varistor blocks and the inner sections of the terminals have substantially equal transverse diameters. A non-conductive filament winding is wrapped around the varistor blocks and inner sections of the terminals and applies an axially-directed compressive force on the varistor blocks and the terminals to maintain electrical connection thereof, the winding having a substantially constant diameter outer surface substantially equal in diameter to the outer sections of the terminals.
Elastomeric 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 filament winding.
More particularly, 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 preferred embodiments of the invention.
Drawings Referring to the drawings which form a part of this original disclosure:
Fig. 1 is a side elevational view, in longitudinal section, showing a surge arrester constructed in accordance with the principles of this invention;
Fig. 2 is a side elevational view, in section, of a modified filament wrapped assembly comprising a plurality of MOV
blocks, spring washers and spacers which are filament wrapped in several layers in accordance with the principles of this invention;

Fig. 3 i~ a s~de elev~tional view of a pre-cured polymeric weathershed housing which is designed to receive the filament wrapped ~OV blocks;
Fig. 4 is an enlarged transverse cross-sectional view of a filament winding which may be used in accordance with this invention and comprises a plurality of strands;
Fiq. S is a side elevational view of an electrical device in accordance with the invention including a plurality of modular and interchangeable filament wrapped electrical assemblies enclosed ~n a weathershed housingS
Fig. 6 i8 a side elevational view in partial longitudinal sect$on of the device shown in ~ig. 5 showing the electrical assemblies including the filament windings inside the weathershed hou~ingS
Fig. 7 is a side elevational view in longitudinal section of the device shown in Fig. 5 and is similar to Fig.
6 but shows the inside of the electrical assemblies; and Fig. 8 i~ an enlarged and exploded s'ide elevational view in longitudinal section of one of the electrical assemblies shown in Figs. 6 and 7.

Detailed Description of the Invention As seen in Figs, 1, 2, and 3, the invention may take the form of a surge arrester 10 comprising a filament wound core of MOV blocks 11 and 12, first and ~econd terminal p~ece~ 16 and 18, filament windings 14, and a polymeric weat~ershed hou~ing 20, $he blocks 11 and 12 are separated by a spring wa~her 13, and load and current distributing washer~ 5 and 6.
As ~een in Fig. 2, a modified filament wound electrical assembly 15 may comprise three MO~ blocks 22, 24 and 26, conducting ~pacer~ 28, 30, 32 and 34, ~pring washers 36 and 38, f~lament windings 14, and first and second terminal pieceQ ~6 and 18, having first and second circumferential grooves 1~ and 19. W~ndings 14 provide a plurality of layers over the ~O~ block~.

Fig. 3 show~ the pre-cured polymeric weathershed housing 20, which is des~gned to receive the filament wrapped assembly 15 shown in Fig. 2 as well as that shown in Fig. 1.
The MOV blocks furnish a predetermined non-l$near electrical characteristic between the ends thereof in a well known fashion. The bloc~s themselves are usually in the shape of relatively short cyl~nders and may be stacked within the housing in a row either in intimate contact with each other, or separated by one or more spring washers 36 and 38 and/or spacers 28, 30 and 32 as illustrated in Fig.
2. A preferred construction, which is shown in Fig. 1, comprises placing a spring washer 13 and load and current distributing washers 5 and 6 between the two MOV blocks 11 and 12, which are ad~acent to, and in intimate contact with the terminal pieces 16 and 18. This provides an excellent thermal path to ambient and improves operating characteristics when thermal stability i8 a factor.
The filament windings 14 may be comprised of any suitable continuous fiber such as nylon, rayon, glass and polyethylene. Other fibers such as ceramic fibers may also be used. A glass filament winding is preferred.
The filament windings 14 may be in the form of a single fiber, or each winding may be comprised of many smaller strands lS as depicted in Fig. 4.
The filament windings may optionally carry a resinous material. The resin may be either natural or synthetic, and may be in tbe partially cured or uncured state. While epoxy resins are preferred, any other suitable resin may be used.
Tbe polymeric weathershed houslng 20 generally may be of any shape and size which will ach~eve the desired effects of providing a shatterproof enclosure having high impact strength and good weather re~stance. ~he weathershed housing may be comprisea of a r$gid or elastomeric polymer, 3s and may be either ~ynthet~c, natura~, or a combination thereof. Examples of such polymers are natural and synthet~c rub~ers, synthetic thermoplastic elastomers, such _ 7 _ 1334300 .
as nylon, po~y~inylchlor~de, and polyethylene (linear), and thermosetting elastomer~ such as polyethylene (cro~s-linked), and polyester~. The preferred weathershed elastomer i~ ethylene-propylene rubber (SPM).
The terminal pieces 16 and 18 may be comprised of any conductive material, preferably a highly conductive metal, and should preferably contain circumferential annular groove~ to aid in the process of winding the filament.
In Fig~. 1 and 2, the circumferential grooves or recesses I7 and 19 are shown as having vertical sidewalls 21, 23, 25 and 27, i.e., sidewalls whose surfaces are perpendicular to the longitudinal central axis of the aligned components and form shoulders that radially extend.
These sidewall~ are joined by annular curved bottom walls 29 and 31. In practice, these grooves may be of any configuration which will serve the purpose of retaining the windings or they may be merely substantially radially extending shoulders.
~he spring washers and ~pacers themselves are conventional and need not be described in detail.
While the discussion has centered on the use of MOV
blocks, it should be understood that the invention contemplates and Figs. 1 and 2 also depict the use of other electrical components such as resistors, capacitors, and in~ulators in place of, or in addition to, MOV blocks. Such arrangements will be useful for other types of electrical assemblies.
It 6hould also be noted that while the drawings illustrate components having a right circular cylindrical configuration, "cylindrical", as defined for the purposes of this invention is broadly defined as the surface traced by a straig~t line Doving parallel to a f~xed straight line and inter~ecting a fixed cur~e. A curve i5 the intersection of two geometrical surfaces. Also, the ter~ ~axial~, for the purpo~es of th~ invention, refers to the longitudinal central aYis of the ~tructure. ~hus, while cylindrical bloc~s are preferred, blocks hav~ng a polygonal cross section may be used.

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1 3343~0 The method for making the surge arrester of this - ~nvention comprises a first step of aligning a plurality of MOV blocks, with or without $nterposed spacers and/or spring washers, under an axial load. This invention contemplates the use of any ax~al load from about 2n pounds per square inch of bloc~ cross ~ection up to ~ust less than the crushing Rtrength of the blocks employed. The preferred ; range is from about 50 pounds per square inch to 500 pounds per square inch of block cross section.
10Any known manner for placing the aligned MOV ~locks under an axial load would be acceptable provided it facilitates the wrapping process. One acceptable method is to align the block~ in a lathe-type apparatus capable of providing an axial load.
15Once the plurality of MOV blocks, with or without spacers and spring washers, is aligned and placed under an axial load, it is ready to be filament wrapped. Any suitable method for filament wrapping the aligned components is acceptable provided that it will retain the aligned components under the specified ax$al load. The preferred method for wrapping the aligned components comprises a helical and overlapping wrapping at a relatively low helical angle and is as follows. First, the filament winding is secured over the shoulder of one terminal piece. Then the 2s components are rotated approximately 180, while the filament is drawn axially along the surface of the assembled components. Upon reaching the opposite terminal piece, the filament is wound over the other shoulder for approximately another 180-. The wind~ng machine then sends the filament back to the ~tarting terminal while the components rotate another 180. Again, the filament makes a half turn in the terminal groove a~d this cycle is repeated as many times as is desired. The degree of rotation and the axial traverse are slightly out of synchronism so that subsequent cycles will advance the windings aro~nd tbe ~rface of the components. Multiple cycles will ult~mately cover the entire surface with the filament. A partially covered as~embly u~ing this winding pattern is illustrated in Fig.
. Additional layers of winding may be added for additional strength as shown in Fig. 2.
In practice, if the degree of rotation and the axial traverse are approximately seven degrees out of synchronism, twenty-five cycles will approximately cover the entire ~urface, and 100 cycles will provide four layer~ of winding for additional strength.
It should be understood that this process does not require axial rotations of 180. Rather, any axial rotation is acceptable provided that a wrap results which will retain the component~ under an axial load. In other words, upon reaching a terminal end, the filament could be wrapped around the shoulder for more or less than 180. Also, the filament may be drawn axially along the aligned components with lesser or greater rotational movement between the components and the filament.
Also, lf a notched shoulder is used, no relative rotation need be used thereby allowing for pure axial lay of the filament wlthout slippage at the shoulder.
As previously mentioned, the filament winding may carry a resinous compound. The resinous compound may be applied to the filament w~nding by any number of means such as pre-coating the filament in a resinous bath, or applying the re~inous compound to the filaments after the components have been wrapped. Additionally, the resinous compound may be either in the semi-cured or uncured ~tate. If the resinous compound i8 in the uncured state, curing will take place at a later time, preferably during application of the polymeric weathershed hou~ing.
Once the components have been wrapped, the weathershed housing may be applied. A~ previou~ly mentioned, the hou~ing preferabiy comprises a polymeric compound. ~his application can be done in numerous ways, ~uch as by inserting the f~lament wrapped asse~ly into a pre-cured ela~tomeric polymer weather~bed. If the filament winding carries an unc~red re~inou~ compound, the windings may be ~:.

1 3343~

-adhesively bonded to the pre-cured weathershed in an oven to create a finished arrester. Other methods such as molding, spraying, or dipping may be used to provide a polymeric weathershed onto the filament wound components. Virtually any method which achieves the desired resuLt i~ acceptable.
When a precured elastomeric weathershed is used, the housing is straight walled inside as shown in Fig. 3. This facilitates assembly. In practice, the outer end diameter of the terminal pieces is made equal to the diameter of the wound assembly. The diameter of the shoulder is less by the thickness of glass over the shoulder. After the body of the assembly is wound, any remaining groove is fillèd with resin-wetted glass wound circumferentially at both ends.
The finished assembly should, to the extent possible, approximate a smooth cylinder as shown in Fig. 2.
Again, while the invention has been illustrated in terms of a surge arrester, the ~process for providing filament windings can be applied to any suitable electrical assembly comprising elements such as resistors, capacitors, and insulators inste~ad of, or in addition to, MOV parts.
If other components are added to or substituted in the assembly, a similarly shaped electrical assembly should result. The length to radius ratio may be different than that normally associated with surge arresters, however, the concept of providing a filament wrapped electrical assembly will remain.

Embodiment of Figs. S-8 Referring to Figs. 5-8, an electrical device 50 in accordance with the invention is shown formed of a plurality of modular electrical assemblies 52, 54 and 56 enclosed in a polymeric, ela~tomeric weathershed hou~ing 58. ~ach of the electrical assemblies is similar to those disclosed above regarding Fig~ 4, is advantageously substantially identical to and interchangeable with the other electrical assemblies, and is in turn formed from a plurality of cylindrical electrical components 60 and 62. These ~

- 11 - 1 3343~
.
component~ are aligned in a row, and are in electrical connection with one another via thelr axially-directed ends and under an axially-directed compressive force via a nonconduct~ve fllament winding 64, as disclosed above regarding Figs. 1-4. The electrical components can be varistors, resistors, capacitors, insulators, or any combination thereof. While only two electrical components are shown in Figs. 5-7, more than two can be used.
In the case of varistors used to form a surqe arrester, voltage rating~ can be enlarged merely by serially and ~electively coupling the plurality of modular electrical assemblies together mechanically and electrically.
The weathershed housing 58 can be one section of polymeric material or a plurality of sections 66, 68 and 70 lS in an end-to-end aligned serial array as seen in Figs. S-8.
These sections receive the electrical assemblies therein via a slight interference fit and therefore facilitate construction and allow the practice of good dielectric design by reducing radial gaps.
Each of the electrical assemblies 52, 54 and 56 are substantially the same, so only a~sembly 52 seen in Figs.
6-8 will be described in detail. 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, ~pring washer 82, and $econd end member, or terminal 84. The nonconductive filament winding 64 is coupled to end members 72 and 84 via reception in peripheral grooves 73 and 85 respectively therein, enclo~es the electrical components, and maintains them under an axially-directed force, which is augmented by the ~pring was~ers. All of the parts comprising electr~ca~ as~embly 52 are conductive except the winding, u~les~ the component6 are insulators.
Advantageou~ly, end member~ 72 and 84 are fonmed from alumlnum. The exposed outer surfaces of the filament windlng 64 and the end members 72 and 84 are all - 12 - l 3 3 4 3 00 substantially cylindrical and have substantially equal diameters.
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 soc~ets 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 shoulder bolt. End plate 92 is received on end stud 90, tightly engages an end of the weathershed housing as seen in Figs. 5-8, and is held in place via rigid shoulder 94 on the stud. 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 shoulder 99 on the stud. Studs 90 and 9~ in essence form external terminals for the overall device 50. Each weathershed housing as seen in Fiqs. 5-7 has a plurality of weathersheds thereon with substantially t~e same outer diameter and root diameter, each of the end plates 92 and 96 having an outer diameter greater than the root diameter but less than the outer diameter of the weathersheds.
Weathershed housing section 66 has a through passageway in the form of a throughbore with an inwardly facing 2S cylindrical surface 100 which tightly receives therein the outer cylindrical surface of the electrical assembly 52.
The same is true regarding sections 68 and 70 and assemblies 54 and 56. The reception of the assemblies in the throughbore is preferably via an interference fit with the assemblies having outer surface diameters that are substantially equal to one another and from about 2% to about 9% greater than the throughbore diameter, which is substantially constant along its length. This reduces radial gaps and thus provides advantageous dielectric desig".
To mechanically and electrically connect the three electrical assemblies 52, 54 and 56 together in an aligned, straight end-to-end serial array, a pair of externally threaded, metallic, and conductive studs 102 and 104 are used, as seen in Figs. 6 and 7. These studs are advantageously substantially identical and interchangeable, as well as substantially rigid and formed of stainless steel. Stud 102 couples the adjacent ends of adjacent assemblies 52 and S4 by being threadedly received in the threaded sockets in each assembly's adjacent end member, and the same is true regarding stud 104 and adjacent assemblies 54 and 56. 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. If more assemblies are used, additional studs are added to connect them, with the addition of any necessary weathershed housing sections, or use of a larger, ; one-piece housing. As seen in Fig. 8, stud 102 is receivable in socket 88.
To provide sealing against water invasion, preferably a neoprene gasket is interposed between each adjacent stud shoulder and 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. U6e 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.
Advantageously as seen in Figs. 5-8, the longitudinal axes of the studs 90, 102, 104, and 98; the electrical components in each assembly 52, 54 and 56; and the weathershed housing 58 are coaxially aligned. Preferably, the planar ends of the end members are perpendicular to these aligned longitudinal axes.
Preferably, with regard to the electrical device 50 shown in Figs. 5-8, the axial load on the electrical components before w~nding is about 750 pounds per s~uare inch, and the filament is wet epoxy coated f$berglass which i8 wound through about 100 turns and is cured for about two hours at 150C.

~_ - 14 -Whi}e various embodiments have ~een chosen to il~ustrate the invention, it will be understood by those skilled in the art that var$ous changes and modifications can be made t~erein without departing from the scope of the invention as defined in the appended claims.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An electrical device, the combination comprising:
a plurality of conductive electrical assemblies, each electrical assembly having first and second ends and substantially cylindrical outer surfaces with substantially similar diameters, said assemblies being oriented in an end-to-end serial array;
means, coupled to each pair of adjacent electrical assemblies, for electrically and mechanically coupling each adjacent pair of electrical assemblies, said mechanical coupling resisting relative axial movement between said electrical assemblies;
weathershed means, completely enclosing said assemblies and said means for electrically and mechanically coupling, for protecting said assemblies and said means for electrically and mechanically coupling;
said weathershed means having a substantially cylindrical throughbore with substantially the same diameter as the diameters of each of said electrical assemblies outer surfaces; and terminal means, coupled to each of the two electrical assemblies at opposite ends of said serial array.

2. An electrical device according to claim 1, wherein said electrical assemblies each comprise a plurality of varistors.

3. An electrical device according to claim 1, wherein said means for electrically and mechanically coupling comprises a threaded connector.

4. An electrical device according to claim 3, wherein said threaded connector comprises a threaded stud.

5. An electrical device according to claim 1, wherein said means for electrically and mechanically coupling comprises a conductive, externally threaded stud, a first conductive end member having a first internally threaded socket receiving one end of said stud, and a second conductive end member having a second internally threaded socket receiving the second end of said stud.

6. An electrical device according to claim 1, wherein said weathershed means comprises a plurality of weathershed housings in an end-to-end, continuous serial array.

7. An electrical device according to claim 1, wherein said weathershed means comprises a pair of end plates tightly engaging the opposite ends of said throughbore.

8. An electrical device according to claim 1 wherein said weathershed means is formed from elastomeric material.

9. An electrical device according to claim 1, wherein said weathershed means is formed from polymeric material.

10. An electrical device according to Claim 1, wherein said cylindrical outer surfaces on said electrical assemblies have diameters which are from about 2% to about 9% greater than the diameter of said throughbore.

11. An electrical device according to Claim 1, wherein said electrical assemblies are received in said throughbore via an interference fit.

12. An electrical device, the combination comprising:
a plurality of conductive electrical assemblies, each electrical assembly having first and second ends, said assemblies being oriented in an end-to-end serial array;
means, coupled to each pair of adjacent electrical assemblies, for electrically and mechanically coupling each adjacent pair of electrical assemblies, said mechanical coupling resisting relative axial movement between said electrical assemblies;
weathershed means, completely enclosing said assemblies and said means for electrically and mechanically coupling, for protecting said assemblies and said means for electrically and mechanically coupling, and terminal means, coupled to each of the two electrical assemblies at opposite ends of said serial array, each of said electrical assemblies including a plurality of conductive electrical components aligned in a row and having axially-directed ends, said electrical components being in electrical connection with one another via said axially-directed ends, and means, wrapped around said components, for applying an axially-directed compressive force on said plurality of electrical components to maintain said electrical connection thereof, said means for applying an axially-directed compressive force including a nonconductive filament winding.

13. An electrical device according to claim 12, wherein said means for electrically and mechanically coupling comprises a conductive, externally threaded stud, a first conductive end member having a first internally threaded socket receiving one end of said stud, and a second conductive end member having a second internally threaded socket receiving the second end of said stud.

14. An electrical device according to claim 12, wherein said weathershed means comprises a plurality of weathershed housings in an end-to-end serial array.

15. An electrical device according to claim 14, wherein each of said electrical assemblies has a substantially cylindrical outer surface, and each of said weathershed housings has a substantially cylindrical throughbore having substantially the same diameter as the outer diameter of each of said electrical assemblies' outer surfaces enclosed therein.

16. An electrical device according to claim 12, wherein said terminal means comprises a first conductive, externally threaded end stud, a first conductive end member having a first internally threaded socket receiving one end of said first end stud, a second conductive, externally threaded end stud, and a second conductive end member having a second internally threaded socket receiving one end of said second end stud.

17. An electrical device according to claim 16, wherein said terminal means further comprises a first end plate coupled to said first end stud and engaging said weathershed means, and a second end plate coupled to said second end stud and engaging said weathershed means.

18. An electrical device according to claim 12, wherein said end-to-end serial array is substantially straight.

19. An electrical device according to claim 12, wherein said means for applying an axially-directed compressive force includes at least one spring washer.

20. An electrical device according to claim 12, wherein said plurality of conductive electrical components comprise at least one contact disc and at least one varistor.

21. An electrical device according to claim 12, wherein said plurality of conductive electrical components comprise at least one resistor.

22. An electrical device according to claim 12, wherein said plurality of conductive electrical components comprise at least one capacitor.

23. An electrical device according to claim 12, wherein said weathershed means is formed of polymeric material.

24. An electrical device according to claim 12, wherein each of said electrical assemblies has a substantially cylindrical outer surface, and said weathershed means has a substantially cylindrical throughbore having substantially the same diameter as the outer diameter of each of said electrical assemblies' outer surfaces enclosed therein.

25. A modular electrical assembly, the combination comprising:

a plurality of conductive electrical components aligned in a row, said electrical components having axially-directed ends and being in electrical connection via their axially-directed ends;
a first electrically conductive terminal located at a first end of said row, said first terminal having first and second axially-directed ends and being in electrical connection with said electrical components via said first axially-directed end thereof and having an axially-directed surface facing in a direction opposite said first axially-directed end thereof;
a second electrically conductive terminal located at a second end of said row, said second terminal having first and second axially-directed ends and being in electrical connection with said electrical components via said first axially-directed end thereof and having an axially-directed surface facing in a direction opposite said first axially-directed end thereof;
connecting means, in said second end of at least one of said terminals, for electrically and mechanically coupling said one terminal to an adjacent, similarly constructed modular electrical assembly, said mechanical coupling resisting relative axial movement between coupled modular electrical assemblies; and compression means, coupled to said first and second terminals, for axially compressing said electrical components and said first and second terminals together as a unit, said means comprising a non-conductive filament winding enclosing and axially compressing said electrical components and engaging said axially-directed surfaces.

26. A modular electrical assembly according to claim 25, wherein said first axially-directed end on said first terminal is substantially planar, and said first axially-directed end on said second terminal is substantially planar.

27. A modular electrical assembly according to claim 26, wherein said second axially-directed end on said first terminal is substantially planar, and said second axially-directed end on said second terminal is substantially planar.

28. A modular electrical assembly according to claim 25, wherein said compression means comprises a first peripheral groove located in said first terminal and receiving a part of said filament winding therein, and a second peripheral groove located in said second terminal and receiving another part of said filament winding therein.

29. A modular electrical assembly according to claim 25, wherein said electrical components have substantially cylindrical outer surfaces of substantially equal diameter, said first and second terminal have substantially cylindrical outer surfaces of substantially equal diameter, the diameters of said outer surfaces on said electrical components and said first and second terminals being substantially equal.

30. A modular electrical assembly according to claim 25, wherein said filament winding has a substantially cylindrical outer surface, and said first and second terminals have substantially cylindrical outer surfaces of substantially equal diameter, the diameters of said outer surfaces on said filament winding and said first and second terminals being substantially equal.

31. A modular electrical assembly, the combination comprising:
a plurality of conductive electrical components aligned in a row, said electrical components having axially-directed ends and being in electrical connection via their axially-directed ends;

a first electrically conductive terminal located at a first end of said row, said first terminal having first and second axially-directed ends and being in electrical connection with said electrical components via said first axially-directed end thereon;

a second electrically conductive terminal located at a second end of said row, said second terminal having first and second axially-directed ends and being in electrical connec-tion with said electrical components via said first axially-directed end thereon;

connecting means, in said second end of at least one of said terminals, for electrically and mechanically coupling said one terminal to an adjacent, similarly constructed modular electrical assembly, said mechanical coupling resisting relative axial movement between coupled modular electrical assemblies;
and nonconductive filament winding compression means, coupled to said first and second terminals, for supporting said electrical components in axial compression between said first and second terminals, said compression means having a substantially cylindrical outer surface, said first and second terminals having substantially cylindrical outer surfaces of substantially equal diameter, the diameters of said outer surfaces on said compression means and said first and second terminals being substantially equal and substantially constant throughout entire lengths thereof.

32. An electrical device, the combination comprising:
a plurality of substantially identical and interchangeable modular conductive electrical assemblies in an end-to-end serial array, said electrical assemblies each having a substantially cylindrical lateral outer surface with substantially similar diameter;
each electrical assembly having first and second terminals at opposite ends thereof;
weathershed means, completely enclosing the lateral outer surfaces of said electrical assemblies, for protecting said electrical assemblies;
first means, coupled to adjacent pairs of terminals, for internally electrically and mechanically coupling adjacent electrical assemblies, said mechanical coupling resisting relative axial movement between said electrical assemblies;
and second means, coupled to the two terminals at opposite ends of said serial array, for establishing an external electrical and mechanical connection of the device;
said weathershed means also completely enclosing the lateral outer surface of said first means for protecting said first means and having a substantially cylindrical throughbore of a diameter corresponding to the diameters of each of said electrical assemblies outer surfaces.

33. An electrical device according to claim 32, wherein said first means comprises a plurality of substantially identical and interchangeable threaded members.

34. An electrical device according to claim 32, wherein said first means comprises a plurality of threaded members.

35. An electrical device according to claim 32, wherein said second means comprises a pair of substantially identical and interchangeable threaded members.

36. An electrical device according to claim 32, wherein .

said second means comprises a pair of threaded members ,37. An electrical device according to claim 32, wherein each of said terminals has a substantially cylindrical outer surface and substantially planar opposite axially-directed ends.

38. An electrical device according to claim 37, wherein each of said cylindrical outer surfaces has substantially the same diameter.

39. An electrical device according to claim 32, wherein each of said terminals has a substantially planar axially-directed outer end, adjacent pairs of said terminals having their planar axially-directed outer ends in substantial engagement.

40. An electrical device according to claim 32, wherein each electrical assembly includes a nonconductive filament winding interconnecting said first and second terminals, and a plurality of varistors.

41. An electrical device according to claim 2 wherein said varistors are generally cylindrical metal oxide varistors.

42. An electrical device according to claim 5 wherein said end members are generally cylindrical.

43. An electrical device according to claim 12 wherein said electrical components are generally cylindrical metal oxide varistor blocks.

44. An electrical device according to claim 13 wherein said electrical components are generally cylindrical varistor blocks;
and said end members are generally cylindrical, said varistor blocks and said end members having substantially equally transverse diameters.

45. A modular electrical assembly according to claim 30 wherein said electrical components are metal oxide varistor blocks.

46. A modular electrical assembly according to claim 31 wherein said electrical components are metal oxide varistor blocks.

47. A surge arrester, comprising:

a plurality of arrester modules arranged in an end-to-end array, each of said modules including a plurality of generally cylindrical, metal oxide varistor blocks aligned in a row 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 row, each of said terminals 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 around said varistor blocks and said terminals, 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, conductive externally threaded studs electrically and mechanically coupling each adjacent pair of said modules by threadedly engaging said sockets, said mechanical coupling resisting axial movement between said modules; and weathershed means enclosing lateral surfaces of said modules for protecting said modules, said weathershed means having a substantially cylindrical throughbore with a diameter substantially equal to the transverse diameters of said modules.

48. A surge arrester, comprising:
modular unit having a plurality of substantially cylindrical metal oxide varistor blocks with opposite, substantially planar ends, said blocks being substantially axially aligned and in end-to-end electrically conductive relationship forming a substantially cylindrical block stack of desired electrical surge arresting characteristics and having a stack length, first and second substantially cylindrical, conductive terminals at opposite ends of said stack having axially-directed surfaces facing in directions opposite to said stack, and electrically non-conductive stack loading means, extending along the stack length and circumferentially around all of said blocks and engaging said axially-directed surfaces on said terminals, for axially compressing said stack and for maintaining electrical contact between said blocks, said loading means enclosing said block stack therein and forming a generally cylindrical, non-conductive cover over said block stack having an outer diameter; and an elongated housing of elastomeric material having an axial, substantially cylindrical, interior bore opening at opposite ends thereof receiving said block stack enclosed in said cover through one of said ends of said housing, said bore defining an inner diameter of said housing relative to said outer diameter of said cover for providing close fit therebetween for minimizing gaps between said cover and said housing.

49. A surge arrester according to claim 48, wherein said loading means rigidly supports said block stack against bending about a longitudinal axis thereof.

50. A surge arrester according to claim 49, wherein said loading means is a fiberglass wrapping.

51. A surge arrester according to claim 50, wherein the fiberglass wrapping is coated with a hardenable resin, said resin hardening prior to insertion of said block stack into said housing.

52. A surge arrester according to claim 48, wherein said outer diameter of said cover is about 2% to 9% greater than said inner diameter of said housing.

53. A surge arrester according to claim 48, wherein said electrical terminals are in electrical contact with end-most faces of said block stack, said loading means being wrapped axially around said terminals, whereby the said terminals are held and axially biased against said block stack by said loading means.

54. A surge arrester according to claim 53, wherein an outermost end of each of said terminals has an open-ended axial bore and an elongated electrically-conductive contact mounted axially in said bore of each of said terminals.

55. A surge arrester according to claim 54, wherein said housing is an integral member with radial weathersheds formed thereon, ends of said housing being substantially planer and perpendicular to a longitudinal axis thereof.

56. A surge arrester according to claim 55, wherein a silicone grease is interposed between said cover and said hous-ing.

57. A surge arrester according to claim 53, wherein said terminals are at least partially enclosed by said housing.

58. A surge arrester according to claim 57, wherein said terminals have generally circular cylindrical outer surface portions, and have certain surface portions of lesser diameter than other surface portions to receive and retain said loading means thereon.

59. A surge arrester according to claim 47, wherein each of said terminal second axial ends is substantially planar and perpendicular to the axis thereof, and is in an abutting relationship with an adjacent terminal second axial end to electrically and mechanically couple said terminals together.

60. A surge arrester assembly, comprising:
a modular unit including a plurality of substantially cylindrical metal oxide varistor blocks of substantially equal diameter with opposite, substantially planar ends, said blocks being axially aligned in end-to-end contact forming a substantially cylindrical block stack with desired electrical surge arresting characteristics;
first and second substantially cylindrical, conductive terminals at opposite ends of said block stack and axially-directed surfaces facing in directions opposite to said block stack; and an elongated, electrically non-conductive element having a substantially cylindrical outer surface and enclosing said block stack, said element comprising a plurality of axially disposed filament windings coupled to said axially directed surfaces of said terminals and extending the length of said stack for applying an axially-directed compressive force to said blocks to hold said blocks and terminals in end-to-end contact; and a resilient housing having opposite ends and a substantially cylindrical, interior bore opening at one end of said housing, the bore being accessible for axial entry of the modular unit into said one end of said housing, the bore having a diameter relative to the outer diameter of the element, whereby said element forms a close fit with said bore for reducing gaps between said unit and said housing.

61. A surge arrester assembly for protecting electrical circuits, comprising:
a modular unit including a plurality of substantially cylindrical metal oxide varistor blocks of substantially equal diameter with opposite, substantially planar ends, said blocks being axially aligned in end-to-end contact forming a substantially cylindrical block stack with a longitudinal axis, first and second electrically conductive terminal members disposed at opposite respective ends of said block stack in adjacency with different ones of said blocks located at opposite respective ends of said stack, each of said terminal members having a shoulder portion substantially symmetrical with respect to said longitudinal axis and disposed at an angle thereto, a non-conductive filament cover engaging each of the shoulder portions and extending longitudinally over said blocks for applying an axially-directed compressive force to said blocks and said terminal members to maintain an axial electrical connection between said blocks and terminal members, said cover providing a substantially cylindrical outer surface with parts of said terminal members available for electrical connections to the electrical circuits, and a housing having opposite ends and an axial, resilient inner wall defining a substantially cylindrical, interior bore opening at one end of said housing, the bore providing axial access to the modular unit through said one end of said housing.

62. The assembly according to claim 61 and further comprising first and second conductive terminal posts connected to different ones of said parts of said first and second terminal members, respectively, said posts projecting from different opposite ends of said housing for facilitating the electrical connection of said terminal members to said circuits.

63. A surge arrester assembly for protecting electrical circuits, comprising:
a modular unit including a plurality of substantially cylindrical metal oxide varistor blocks of substantially equal diameter with opposite, substantially planar ends, said blocks being axially aligned in end-to-end relationship forming a substantially cylindrical block stack with a longitudinal axis, first and second electrically conductive terminal members disposed at opposite respective ends of said block stack in adjacency with different ones of said blocks located at opposite respective ends of said stack, each of the terminal members having a shoulder portion substantially symmetrical with respect to said axis and disposed at an angle thereto, a nonconductive filament winding wrapped about each of the shoulder portions and extending longitudinally over said blocks for applying axially-directed compressive forces to said blocks and said terminal members to provide an axial electrical connection between said blocks and terminal members, said winding providing a substantially cylindrical outer surface with parts of said terminal members accessible from opposite ends of said winding for electrical connection to the electrical circuits, and an elastomeric housing having opposite ends and an outer surface formed with a plurality of weathersheds between said ends, and an axial, inner wall defining a substantially cylindrical, interior bore, the housing wall having a diameter which is substantially equal to the outer diameter of the winding for minimizing gaps between said winding and said housing when said winding is received in said housing.

64. A surge arrester assembly for protecting electrical circuits, comprising:
a plurality of substantially cylindrical blocks having non-linear voltage-current characteristics of substantially equal diameter with opposite, substantially planar ends, said blocks being axially aligned in end-to-end relationship to form a substantially coaxial block stack;
first and second electrically conductive terminal members disposed at opposite respective ends of said block stack in adjacency with different ones of said blocks located at said opposite respective ends of said stack, said terminal members having axially facing surfaces;
an elastomeric housing having opposite ends and an axial, interior bore;
non-conductive filament winding means, at least partially enclosing said blocks and engaging said surfaces of said terminal members, for applying an axially-directed compressive force to said blocks and said terminal members, said means applying said force independently of said housing to maintain axial electrical contact between said blocks and said terminal members;
said means, said blocks and said terminal members being received in said bore of said housing.

65. A surge arrester assembly for protecting an electrical circuit, comprising:
a plurality of substantially cylindrical blocks having non-linear voltage-current characteristics of substantially equal diameter with opposite, substantially planar ends, said blocks being axially aligned to form a substantially cylindrical block stack;
first and second axially aligned, electrically conductive, terminal members disposed at opposite respective ends of said block stack in adjacency with different ones of said blocks located at said opposite respective ends of said stack;
an elongated housing comprised of a polymeric electrical insulation having opposite ends and a longitudinal cylindrical bore intermediate said opposite ends; and elongate, non-conductive filament winding means, coupled to said terminal members, for applying and maintaining an axially-directed compressive force to said blocks by way of said terminal members, said non-conductive filament winding means having a substantially smooth and cylindrical outer surface;

whereby said non-conductive filament winding means, blocks and terminal members form a substantially right circular cylindrical module of axially compressed blocks and terminal members of substantially constant diameter along the entire length of said module;
said module being mounted in said bore of said housing with a close fit with portions of said terminal members being accessible from opposite respective ends of said housing for connection to the electrical circuit, whereby said module maintains said compressive force on said blocks and terminal members independently of said housing.

66. A surge arrester assembly for protecting an electrical circuit, comprising:
a plurality of substantially cylindrical blocks having non-linear voltage-current characteristics of substantially equal diameter with opposite, substantially planar ends, said blocks being axially aligned to form a substantially cylindrical block stack;
first and second axially aligned, electrically conductive, terminal members disposed at opposite respective ends of said block stack in adjacency with different ones of said blocks located at said opposite respective ends of said stack;
an elongated housing comprised of a polymeric electrical insulation having opposite ends and a longitudinal cylindrical bore intermediate said opposite ends;
elongate, non-conductive filament winding means, coupled to said terminal members, for applying and maintaining an axially-directed compressive force to said blocks by way of said terminal members, said non-conductive filament winding means having a substantially smooth and cylindrical outer surface, adhesive means applied to said non-conductive filament winding means for rendering said means rigid, whereby said means, blocks and terminal members form a rigid, substantially right circular cylindrical module of axially compressed blocks and terminal members of substantially constant diameter along the entire axial length of said module;
said module being mounted in said bore of said housing with an interference fit with portions of said terminals accessible from opposite respective ends of said housing for connection to the electrical circuit, whereby said module maintains said compressive force on said blocks and terminal members independently of said housing.

67. A surge arrester comprising:
a plurality of substantially cylindrical blocks having non-linear voltage-current characteristics of substantially equal diameter with opposite, substantially planar ends, said blocks being axially aligned in end-to-end relationship to form a substantially coaxial block stack;
first and second electrically conductive terminals disposed at opposite respective ends of said block stack adjacent different ones of said blocks located at said opposite respective ends of said stack;

nonconductive filament winding means, at least partially enclosing said blocks and terminals for applying an axially-directed compressive force to said blocks and said terminals;

a housing having open opposite ends, an axial interior throughbore, and a plurality of weathersheds thereon, each of said weathersheds having substantially the same outer diameter and root diameter, said blocks and terminals being received in said housing; and a pair of disc-shaped end plates, each of said end plates abutting one of said housing opposite ends and having an outer diameter greater than the root diameter of said weathersheds.

68. A surge arrester comprising:
first and second electrically conductive terminals;
at least one non-linear resisting block having first and second axially-directed ends and positioned between said first and second terminals to form a substantially cylindrical structure having a substantially uniform circumferential outer surface;
said first terminal having an axially-directed end thereon in electrical connection with said first axially-directed end of said block, said first terminal including a first surface facing in an axial direction opposite the axially-directed end thereof;
said second terminal having an axially-directed end thereon in electrical connection with said second axially-directed end of said block, said second terminal including a second surface facing in an axial direction opposite the axially-directed end thereof;
a plurality of discrete elongated tensile elements formed of an insulating material and spaced circumferentially around and extending adjacent one another the length of said outer surface and engaging said first and second surfaces of said first and second terminals, said tensile elements being under axial tension to thereby apply an axially-directed compression force to said first and second terminals and said block, whereby transverse bending of the arrester is resisted and said first and second terminals and said block are maintained in electrical connection; and a housing having a cylindrical bore with an inwardly facing substantially cylindrical surface which closely encloses said block, terminals and tensile elements therein.

69. A surge arrester according to claim 68, wherein said tensile elements are joined by adhesive.

70. A surge arrester according to claim 69, wherein at least certain ones of said tensile elements lie in substantially parallel relationship.

71. A surge arrester according to claim 70, wherein said certain ones of said tensile elements lie adjacent one another.

72. A surge arrester according to claim 71, wherein other ones of said tensile elements overlap said certain ones of said tensile elements.

73. A surge arrester according to claim 68, wherein said tensile elements lie in an overlapping relationship throughout the length of said cylindrical structure.

74. A surge arrester according to claim 68, wherein said at least one non-linear resistive block comprises a metal oxide varistor block.

75. A surge arrester comprising:
first and second electrically conductive terminals;
at least one non-linear resistive block, having first and second axially-directed ends and a substantially cylindrical outer surface, positioned between said first and second terminals;
a plurality of elongated tensile elements formed of an insulating material positioned around said block at circumferentially spaced locations;
said first terminal having an axially-directed end thereon in electrical connection with said first axially-directed end of said block, said first terminal including a first surface for engaging said tensile elements;

said second terminal having an axially-directed end thereon in electrical connection with said second axially-directed end of said block, said second terminal including a second surface for engaging said tensile elements;
said tensile elements engaging said first and second surfaces and being axially tensioned to thereby apply an axially-directed compression force to said first and second surfaces and said block to resist transverse bending of the arrester and to maintain said first and second terminals and said block in electrical connection; and a housing having a through passageway with an inwardly facing substantially cylindrical surface having a diameter substantially equal to the diameter of said block outer surface with said tensile elements positioned therearound and receiving said block and elements therein.

76. A surge arrester according to claim 75, wherein said at least one non-linear resistive block comprises a metal oxide varistor block.

77. A surge arrester according to claim 75, wherein said at least one non-linear resistive block comprises a plurality of non-linear resistive blocks.

78. A surge arrester according to claim 75, wherein at least certain ones of said tensile elements lie in substantially parallel relationship.

79. A surge arrester according to claim 75, wherein said tensile elements lie in an overlapping relationship.

80. A surge arrester, comprising:
a modular unit having a plurality of substantially cylindrical metal oxide varistor blocks with opposite, substantially planar ends, said blocks being substantially axially aligned and in end-to-end electrically conductive relationship forming a substantially cylindrical block stack of desired electrical surge arresting characteristics and having a stack length;
first and second substantially cylindrical, conductive terminals at opposite ends of said block stack and having axially directed surfaces facing in directions opposite to said block stack; and electrically non-conductive stack loading means, extending along the stack length and circumferentially around all of said blocks and engaging said axially directed surfaces of said terminals for axially compressing said stack and for maintaining electrical contact between said blocks;
said loading means enclosing said block stack therein and forming a generally cylindrical, non-conductive cover over said block stack having an outer diameter whereby transverse bending is resisted; and an elongated housing of elastomeric material having an axial, substantially cylindrical, interior bore opening at opposite ends thereof for axial entry of electrical currents to said block stack enclosed in said cover through one of said ends of said housing, said bore defining an inner diameter of said housing which is such as to provide a closely adjacent fit between said housing and said cover and thereby minimize gaps between said cover and said housing.

81. A surge arrester assembly for protecting an electrical circuit, comprising:
a plurality of substantially cylindrical blocks having non-linear voltage-current characteristics of substantially equal diameter with opposite, substantially planar ends, said blocks being axially aligned to form a substantially cylindrical block stack;
first and second axially aligned, electrically conductive, terminal members disposed at opposite respective ends of said block stack in adjacency with different ones of said blocks having axial ends located at said opposite respective ends of said stack and axially directed surfaces facing in an axial direction opposite said ends of said blocks;
an elongated housing comprised of a polymeric electrical insulation having opposite ends and a longitudinal cylindrical bore intermediate said opposite ends;
elongate, non-conductive filamentary wrap means, coupled to said axially-directed surfaces of said terminal members, for applying and maintaining an axially-directed compressive force to said blocks by way of said terminal members, said non-conductive filament wrap means having a substantially smooth and cylindrical outer surface and being sufficiently rigid whereby said wrap means, blocks and terminal members form a rigid, substantially cylindrical module of axially compressed blocks and terminal members resistant to transverse bending;
said module being mounted in said bore of said housing with a closely adjacent fit with portions of said terminals accessible from opposite respective ends of said housing for connection to the electrical circuit, whereby said module maintains said compressive force on said blocks and terminal members independently of said housing.

82. A surge arrester comprising:
a plurality of substantially cylindrical blocks having non-linear voltage-current characteristics of substantially equal diameter with opposite, substantially planar ends, said blocks being axially aligned in end-to-end relationship to form a substantially coaxial block stack;
first and second electrically conductive terminals disposed at opposite respective ends of said block stack adjacent different ones of said blocks located at said opposite respective ends of said stack;
non-conductive filamentary wrapping, at least partially enclosing said blocks and terminals for applying an axially-directed compressive force to said blocks and said terminals;
a housing having open opposite ends, an axial interior bore and a plurality of weathersheds thereon, each of said weathersheds having-substantially the same outer diameter and root diameter, said blocks and terminals being received in said housing; and a pair of disc-shaped end plates, each of said end plates abutting one of said housing opposite ends and having an outer diameter greater than the root diameter of said weathersheds.

83. An electrical device, the combination comprising:
a plurality of conductive electrical assemblies, each electrical assembly having first and second ends, said assemblies being oriented in an end-to-end serial array;
means coupled to each pair of adjacent electrical assemblies, for electrically and mechanically coupling each adjacent pair of electrical assemblies, said mechanical coupling resisting relative axial movement between said electrical assemblies;
weathershed means completely enclosing lateral outer surfaces of said assemblies and said means for electrically and mechanically coupling, for protecting said assemblies and said means for electrically and mechanically coupling; and terminal means coupled to each of the two electrical assemblies at opposite ends of said serial array;
each of said electrical assemblies including a plurality of conductive electrical components aligned in a row and having axially-directed ends, said electrical components being in electrical connection with one another via said axially-directed ends; and non-conductive means wrapped around said components, for applying an axially-directed compressive force on said plurality of electrical components to maintain said electrical connection thereof;
said means for applying an axially-directed, compressive force including filamentary material which also resists transverse bending of the device.

84. A surge arrester, the combination comprising:
at least one non-linear resistive block having first and second axially-directed ends;
a first electrically conductive terminal having an axially directed end thereon in electrical connection with said first axially-directed end of said block and an axially-directed surface thereon facing in a direction opposite the axially-directed end thereof;
a second electrically conductive terminal having an axially directed end thereon in electrical connection with said second axially-directed end of said block and an axially-directed surface thereon facing in a direction opposite the axially-directed end thereof; and a non-conductive filament wrapped around said block and wrapped around and engaging said axially-directed surfaces on said terminals, said filament being axially tensioned to thereby apply an axially-directed compression force to said terminals and said block to resist transverse bending of the arrester and to maintain said terminals and block in electrical connection.

85. A surge arrester according to claim 84, wherein said non-conductive filament engages said block.

86. A surge arrester according to claim 84 and further including a resilient housing receiving said block, terminals and non-conductive filament therein.

87. A surge arrester according to claim 84, wherein said axially-directed ends of said terminals are substantially planar.

88. A surge arrester according to claim 87, wherein said axially-directed ends of said block are substantially planar.

89. A surge arrester according to claim 84, wherein said filament has a substantially cylindrical surface, and said first and second terminals have substantially cylindrical outer surfaces of substantially equal diameter, the diameters of said outer surfaces on said filament and said first and second terminals being substantially equal.

90. A surge arrester according to claim 84, wherein said non-conductive filament engages said block, said axially-directed ends of said terminals are substantially planar, said axially-directed ends of said block are substantially planar, said filament has a substantially cylindrical outer surface, and said first and second terminals have substantially cylindrical outer surfaces of substantially equal diameter, the diameters of said outer surfaces on said filament and said first and second terminals being substantially equal.

91. A surge arrester according to claim 90 and further including a resilient housing receiving said block, terminals and non-conductive filament therein.

92. A surge arrester according to claim 91, wherein said resilient housing has a through passageway having an inwardly facing, substantially cylindrical surface having a diameter substantially equal to the diameters of said outer surfaces of said filament and said first and second terminals.

93. A surge arrester according to claim 91, wherein said resilient housing has a through passageway having an inwardly facing, substantially cylindrical surface in an interference fit with said outer surfaces of said filament and said first and second terminals.

94. A surge arrestor, comprising:
a plurality of generally cylindrical, metal oxide varistor blocks aligned in a row 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 row, 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 terminals having inner sections adjacent said first axial ends and outer sections adjacent said second axial ends, said inner sections being narrower than said outer sections, said varistor blocks and said inner sections of said terminals having substantially equal transverse diameters;
a non-conductive filament winding wrapped around said varistor blocks and inner sections of said terminals and applying an axially-directed compressive force on said varistor blocks and said terminals to maintain electrical connection thereof, said winding having a substantially constant diameter outer surface substantially equal in diameter to said outer sections of said terminals; 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 filament winding.