JP2520467B2 - Modular electrical assembly and surge arrester - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention is an electrical assembly housed in a polymer and configured as a module that can be electrically coupled together to alter the overall electrical rating of the device. It is about.
Each electrical assembly is composed of electrical components wound with non-conductive filament windings in a pattern with openings for venting gas pressure. The components can be varistors, resistors, capacitors or any combination of these components.

[Problems to be Solved by Prior Art and Invention]

To shunt overcurrent surges, surge protectors or surge arresters are commonly connected to the more expensive components of electrical equipment, such overcurrent surges occurring, for example, during lightning strikes. When a lightning strike occurs, the surge arrester will pass the surge to ground, thereby protecting the electrical equipment components and circuits from damage.

Current surge arresters generally include an elongated, hollow cylindrical housing made of porcelain or the like and a plurality of non-linear resistance blocks within the housing. Some of these structures also include spark gaps, where blocks and gaps are electrically connected to handle voltage and current surge conditions that occur on power lines. Block is silicon carbide (SI
C) or a metal oxide varistor (MOV) is generally included and usually takes the form of a relatively short cylinder stacked inside the arrester housing. The number of blocks used depends on the material (SI
C or MOV) and the voltage and current ratings of the assembly.

The MOV block or SIC block must be in close contact for the surge arrester to work properly.
To do this, axial loads must be applied to the blocks inside the housing. Conventional arresters use large contact springs within the housing to apply their axial loads. Typically, those springs can only bear relatively small loads, for example about 27 kg (about 60 pounds). As a result, conventional arresters have one or more problems such as low thermal conductivity between MOV blocks or SIC blocks, uneven current distribution, and high contact resistance at the junction. is there. In addition, units with low contact force spatter and the ionized metal that is produced can cause axial flashover at high currents.

Another problem with conventional surge arresters is that they rarely fail in dangerous situations. If the arresters fail and a large fault current flows to generate a high internal gas pressure, the device may explode, and the debris scattered by the explosion may destroy objects around the device.

Also, some of the conventional devices are difficult to fabricate, have poor dielectric design, can be flooded, and require completely different devices when the voltage rating changes.

An example of a conventional surge arrester is disclosed in the following US patents. No. 2,587,587, No. 2,947,903, No. 2,997,529
No., 3,018,406, 3,261,910, 3,412,273,
No. 3,524,107, No. 3,566,183, No. 3,567,541, No. 3,5
86,943, 3,706,009, 3,725,745, 3,850,72
No. 2, No. 3,973,172, No. 3,987,343, No. 4,029,380,
No. 4,092,694, No. 4,100,588, No. 4,107,567, No. 4,1
61,012, 4,218,721, 4,404,614, 4,467,38
7, 4,491,687, and U.S. Defense T102,103, British Patents 730,710, 1,109,151, and 1,505,875.
issue.

US Pat. Nos. 4,656,555 and 1 assigned to the applicant
Pending US Patent Application No. 033,765, dated April 3, 987, and "Modular Electrical Assembly with Plastic Barrier Membrane, filed on the same date as this application.
In a surge arrester disclosed in a pending US patent application entitled "Assembly With Plastic Film Barriers)", resin-impregnated glass fibers completely surround the varistor blocks and axially compress the varistor blocks. When the varistor block is completely enclosed in this way, it cannot escape into the gas weathershed housing that occurred when the varistor block failed, and then out of the housing.
Before that, the pressure of the gas becomes too high and the assembly is destroyed. The relatively thin filament coverings allow the wound material to burn and tear before the very high pressures occur.

Therefore, an object of the present invention is to allow the gas to escape in order to minimize the damage caused by the gas that occurs when the electric component fails, and the dielectric design is good, and it is not flooded.
To obtain an electrical assembly, in particular for surge arresters, which has modular components and a housing for easily changing the voltage rating.

Another object of the present invention is to provide a large axial load, which results in a uniform current distribution, low resistance at the junction, and excellent heat transfer to the terminals of the arrester, such as a surge arrester. To get an electrical assembly.

Another object of the invention is to obtain an electrical assembly, such as a surge arrester, which has a high impact strength, a housing which does not fail in a dangerous manner and does not shatter upon explosion.

Another object of the invention is to obtain a MOV block assembly with very high tensile strength and cantilever strength.

Yet another object of the present invention is to provide a surge arrester that allows dimensional changes in the associated components, thereby eliminating the need to use costly, low tolerance components.

[Means for solving the problem]

Their purpose is to provide a plurality of electrically conductive electrical components arranged in rows or columns and electrically connected via axially oriented ends, and non-conductive electrical components wrapped around those electrical components. And a modular electrical assembly including a fiber filament winding. The windings apply an axially directed compressive force to the electrical components to maintain their electrical connection and form a pattern with openings that allow the escape of gas generated when one of the electrical components fails. To do.

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to the drawings.

Referring first to FIGS. 1-3, an electrical device 50 in the form of a surge arrester comprises a modular electrical assembly 52 of the present invention contained within a resilient weatherproof housing 58 made of polymer. It Advantageously, the assembly shown is substantially identical to and compatible with other electrical assemblies. The electrical assembly is formed of one or more cylindrical electrical components 60,62. Those parts are
U.S. Patent No. 4,656,555 and pending U.S. Patent Application No. 033,7
As disclosed in No. 65, they are aligned with each other under their axial compressive forces generated by the non-conductive filamentary windings 64, through their respective axial ends. It is electrically connected. Examples of electrical components include metal oxide varistor (eg, zinc oxide varistor block), resistor,
It can be a capacitor or any combination thereof.

In the case of varistors used to construct surge arresters, multiple modular electrical assemblies can be mechanically and electrically connected in series, or selectively connected in series to increase voltage ratings.

A resilient weatherproof housing 58 receives the electrical assembly therein with a slight interference fit. By doing so, the gap in the radial direction is narrowed, so that the manufacturing is facilitated and a good dielectric design can be performed.

The electrical assembly 52 is generally cylindrical and includes a first end member or terminal 72, a spring washer 74, and a contact disk.
76, electrical component 60, contact disc 78, electrical component 62, contact disc 80, spring washer 82, and second end member or terminal 84. To maintain contact pressure when the electrical assembly bends due to cantilever loading, especially for base mounted assemblies, electrical assembly to the contact disks at some or all of the intermediate varistor joints. Additional spring washers can be used in solids. The non-conductive filament winding 64 is coupled to the end members 72, 84 and surrounds the electrical components and continues to exert an axial force on the electrical components. The axial force is increased by spring washers.

A plastic membrane barrier 110 laterally surrounding the electrical components 60 and 62 is coaxially sandwiched between the electrical components and the filament winding 64. Polypropylene is preferably used as the plastic. The barrier is formed by winding a rectangular sheet of plastic tightly around the adjacent parts of the electrical components and end members 72 and 84 in two layers and then winding a filament winding 64. The thickness of the plastic sheet and each layer is about 0.0127 mm (about 0.005 inch).

Because the plastic membrane barrier extends along the entire length of the electrical component to the end member, the plastic membrane barrier seals the electrical component from the epoxy resin on the filaments that make up the winding. For surge arresters, this prevents fibrous, non-drying epoxy or other resin from joining the fragile ceramic insulating collars on metal oxide varistor blocks 60 and 62. The bond can be prevented by other anti-adhesion agents such as silicone oil or silicone grease.

The end members 72 and 84 are advantageously made of aluminum, but can be made of any other material with suitable electrical conductivity and mechanical strength.

The end members 72 and 84 form internal terminals and have a cylindrical exposed outer surface and have flat first and second axial ends. Are provided with screw holes or sockets 86 and 88, respectively. Socket 8
An end stud 90 made of a conductive metal bolt is screwed into 6. The end stud is connected to the power supply.
A nut is tightened on the end stud. An end plate 92 is received by the end stud 90 and tightly engages the end of the weatherproof housing as shown in FIGS. 1 and 2 and is held in place by the nut 91. For mounting the base, a base plate provided with bolt holes can be mounted. A second end plate 96 is similarly attached to the other end of the housing and is received on the end stud 98. Its end stud 98 is grounded and maintained on it by a nut 99 clamped to it. Studs 90 and 98 form the external terminals for the entire device 50.

A through hole is provided in the weatherproof housing 58. The cylindrical inner surface 100 of the through hole tightly contacts the outer cylindrical surface of the electrical assembly 52. The electrical assembly is preferably a tight fit within its through hole. The outer diameter of the electrical assembly is about 2-9% larger than the inner diameter of the through hole and is substantially constant over its entire length. This choice of diameter reduces the radial clearance and thus allows for an advantageous dielectric design.

Since the end members 72 and 84 are the same, only the end member 72 will be described in detail. With particular reference to Figures 4-6,
The end member 72 has an inner portion 120 and an outer portion 122 separated by a radially extending flange 124. The inner portion 120 is oriented adjacent to and in the direction of the electrical components 60 and 62 and has a cylindrical surface with a diameter approximately equal to the diameter of the electrical components. The inner portion 120 is the end member that receives the membrane barrier 110. The outer portion 122 also has a cylindrical side surface, but the diameter is smaller than that of the inner portion 120.

The plan view of flange 124 is generally circular and extends radially outward from the boundary of portions 120 and 122. Notches 126 are formed in the flange that are radially inwardly recessed and radially outwardly open. In this embodiment, eight uniformly sized notches are circumferentially equally spaced around the flange 124. The number of notches varies depending on the diameter of the part. The larger the diameter of the part, the more notches are used, and the smaller the diameter of the part, the smaller the number of notches used.

The end members facilitate winding non-conductive filaments, such as glass, in a pattern with diamond-shaped lateral openings 128. The opening 128 may be filled with a material 130, such as epoxy, which is capable of fracturing suitable insulating and mechanical properties. Other suitable materials include polyester, foam rubber, silicone grease, or a gas such as air. If the housing were molded around the wrap of the electrical assembly, the molded housing material could fill the opening.

The cruciform winding pattern shown in FIG. 1 shows one filament, and preferably a plurality of filaments (typically nine), which are shown diagrammatically in FIGS. It is formed by winding simultaneously according to the pattern. In this pattern, the end member notches 126 are separated by an angle of 45 degrees. The wrapping method used for a particular arrester is related to the part diameter, length, and mechanical requirements. In these figures, end members 72 and 84 are labeled L and R, respectively. The individual notches 126 in each end member are numbered 1-8, respectively. Since the filaments are moved axially, the assembly is rotated 180 degrees during the transition from one end member to another. The filament is then turned at the end member by an angle of 315 degrees to the next notch position. This particular pattern shown is as follows and is shown in FIG. Rotation from to 1L 5R 180 ° 5R 4R 315 ° 4R 8L 180 ° 8L 7L 315 ° 7L 3R 180 ° 3R 2R 315 ° 2R 6L 180 ° 6L 5L 315 ° 5L 1R 180 ° 1R 8R 315 ° 8R 4L 180 ° 4L 3L 315 3L 7R 180 ° 7R 6R 315 ° 6R 2L 180 ° 2L 1L 315 ° Repeated until the thickness of the thread equals the lateral perimeter spread of the flange 124. The additional fiber filaments are laid on the outer part 12 until the outer circumference of the filaments surrounding the outer part 122 is at least equal to the outermost extent of the flange 124.
Wrapped around 2. The outer surface of the assembly is then ground to the extent necessary to obtain a uniform circumferential surface along the entire length of the assembly.

Insulation material 130 fills the openings 128 to maintain the desired uniform cylindrical surface of the assembly. However, when a suitable pressure is created inside the winding above the breakdown threshold of epoxy or other insulating material, the insulating material 130 may easily break or separate, allowing gas to escape.

When an electrical component fails, gas is released, creating a very high gas pressure in the fiber filament winding. The pressure causes the epoxy or other insulating material to rupture, allowing gas to escape into the weatherproof housing 58. Due to the resilience and flexibility of the resilient weatherproof housing 58, the housing expands to allow gas to flow along the length of the inner surface of the housing and exit from its axial end. To do so. The gas can also exit between adjacent housings that are stacked or through a crevice in the resilient housing. When the gas is released, the housing contracts and reattaches to the assembly 52. If no gas is released, until the rising gas pressure explodes the assembly,
The gas remains trapped in the winding. After the gas is released, the ionized gas creates an external arc that bridges the destroyed arrester and restores the internal failure.

Externally threaded conductive metal studs to mechanically and electrically connect multiple electrical assemblies together into an aligned, end-to-end straight series array. Can be used. It is advantageous for the studs to be nearly identical and compatible, and to be sufficiently sturdy, and are preferably made of stainless steel. The ends of adjacent studs are joined by screwing the studs into the threaded sockets of the adjacent end members of each assembly. Adjacent ends of adjacent assemblies are tightly threaded together on the studs to provide a near-zero engagement between opposing flat axial outer ends of the end members. Advantageous electrical and mechanical boundaries are then obtained by reducing the separation that can occur during bending of the device. Multiple weatherproof housing parts or larger one-piece housings can be used.

To provide a watertight seal, a gasket 140 is provided between each end member and an adjacent end plate to provide a number of adjacent ends and between the end members, between adjacent end members, and electrical assembly. It is preferable that silicone grease is filled between the outer surface of and the inner surface of the through hole of each weatherproof housing part. Filling with silicone grease between the weatherproof housing portion and the electrical assembly aids manufacturing and assembly by reducing friction and the radial clearance between them.

The longitudinal axis of the stud and the electrical components in each electrical assembly,
Advantageously, it is coaxially aligned with the weatherproof housing 58. It is preferred to have the flat ends of the end members perpendicular to their aligned longitudinal axes.

For the electrical device 50, the axial load on the electrical components in front of the winding is about 53 kg / cm ² (about 750 p.si),
The filament or braided element of the fiber is a moist, epoxy coated glass fiber which is wound about 100 times and cured at 150 ° C. for about 2 hours.

[Brief description of drawings]

1 is a partial cross-sectional side view of a modular electrical assembly of the present invention in the form of a surge arrester showing the outer surface of a filament winding, and FIG. 2 is a longitudinal cross-section of the electrical assembly shown in FIG. Fig. 3 is an enlarged end view taken along line 3-3 of Fig. 1, Fig. 4 is an end view of the end member of Figs. 1 and 2, and Fig. 5 is 5 of Fig. 4. Fig. 6 is a sectional view taken along line -5, Fig. 6 is a side view of the end member shown in Fig. 4, and Figs. 7 to 9 show the winding method for forming the pattern of the filament shown in Fig. 1. It is a diagram showing. 50 …… Electric device, 52 …… Modular electric assembly, 58 …… Weatherproof housing, 60,62 …… Electrical components, 64 …… Fiber winding, 72,84 …… End member, 90 …… Stud , 110 …… Barrier, 128 …… Opening, 130 …… Insulating material.

Claims (33)

(57) [Claims] 1. A plurality of electrically conductive electrical components having axially oriented ends, aligned in a row and electrically connected at said axially oriented ends, and Wrapped around the electrical components and applying an axially directed compressive force to the electrical components to maintain an electrical connection between the electrical components and escape gas when one of the electrical components fails A modular electrical assembly comprising: a non-conductive filament winding forming a pattern having lateral openings. 2. The modular electrical assembly of claim 1, wherein the opening is filled with a crushable insulating material. 3. The modular electrical assembly of claim 2, wherein the crushable insulating material is epoxy. 4. The modular electrical assembly of claim 1, wherein an elastic housing coaxially surrounds the filament winding and frictionally engages the filament winding. 5. The modular electrical assembly according to claim 4, wherein the housing is provided with an internal through hole, and the filament winding is tightly fitted in the through hole. 6. The modular electrical assembly of claim 1, wherein a barrier coaxially surrounds the electrical component, the barrier being sandwiched between the electrical component and the filament winding. 7. The modular electrical assembly of claim 1, wherein the electrical component is a varistor. 8. The modular electrical assembly of claim 7, wherein the varistor is a generally cylindrical metal oxide varistor. 9. A first conductive end member and a second conductive end member are disposed at both ends of the electrical component row, and the filament winding is on at least a part of each end member. 2. The modular electrical assembly of claim 1 extending through and surrounding at least a portion thereof. 10. The electrical component is a generally cylindrical varistor block, the end members including cylindrical inner portions, the inner portions having a diameter substantially equal to the varistor block. The modular electrical assembly according to claim 9. 11. Each end member includes a radially extending flange, the flange having circumferentially spaced notches, the notches receiving a portion of the filament winding. A pattern is formed, The pattern is formed.
The modular electrical assembly described. 12. Each end member includes a portion of short diameter on the side of its flange remote from the electrical component,
The filament winding extends around the short diameter portion,
The modular electrical assembly of claim 11, wherein the modular electrical assembly comprises a substantially uniform lateral diameter along an axial length of the electrical assembly. 13. The modular electrical assembly of claim 12 wherein each of said reduced diameter portions is provided with an internal threaded hole. 14. The modular electrical assembly of claim 1, wherein the opening is filled with an insulating material. 15. The modular electrical assembly of claim 14, wherein the insulating material is grease. 16. With an end directed axially, 1
A plurality of generally cylindrical metal oxide varistor blocks aligned in rows and electrically connected to each other via said axially oriented ends, and an axis contacting one of said varistor blocks. A directional end and an opposite second axial end having a socket internally threaded, each having a lateral diameter substantially equal to a lateral diameter of the varistor block. A generally cylindrical first electrically conductive terminal and a second at both ends of the row;
1 of said varistor block for applying an axially directed compressive force to said varistor block and said terminal to maintain its electrical connection. Compression means wound in a crisscross pattern around the varistor block and the terminal, forming a lateral opening in the filament winding for escape of gas in the event of a failure of one. A surge arrester, comprising: a substantially cylindrical through hole having a substantially equal diameter, and elastic weatherproof means for elastically surrounding the varistor block and protecting the varistor block. 17. The surge arrester according to claim 16, wherein the opening is filled with an insulating material. 18. The surge arrester according to claim 17, wherein the insulating material is a crushable epoxy. 19. The surge arrester according to claim 17, wherein the insulating material is grease. 20. The surge arrester according to claim 17, wherein the insulating material is crushable. 21. A non-linear voltage-current characteristic, and
A plurality of cylindrical surge arrester components in which cylindrical components having a longitudinal axis are coaxially aligned as a stack, and each of which is assembled at an opposite end of the stack and electrically connected to the components. First and second conductive terminals having circular surface portions concentric to the longitudinal axis; first and second surrounding the stack and respectively connected to the circular surface portions of the terminals. Sufficient structure having two ends to exert an axial compressive force on the arrester component such that sufficient electrical contact is made between the component of the stack and the terminal. A non-conducting tubular member having upper strength and having bending rigidity transverse to said longitudinal axis, and surrounding said tubular member, at least in part to control the evacuation of evolved gas from the internal assembly. Work for An elastic housing that is prevented from being bent by the tubular member, the tubular member having at least one inlet for discharging gas generated from the stack to the outside through a side portion of the tubular member, and the inlet and outlet being insulated. A surge arrester characterized by being opened so that it can be opened with the filling substance of. 22. The surge arrester according to claim 21, wherein the elastic housing is made of an elastic polymer material. 23. The surge of claim 21, wherein the tubular member is composed of a fiber material impregnated with a resin, and a part of the resin forms at least a part of the filling substance. Arrester. 24. The surge arrester according to claim 23, wherein the inlet / outlet is an opening having a predetermined size and shape that laterally extends through the fiber material. 25. The surge arrester according to claim 24, wherein the filament material is formed by winding multiple continuous twisted yarns so as to form a cruciform pattern as a whole. 26. The surge arrester according to claim 25, wherein the inlet and outlet are rhombic. 27. The surge arrester according to claim 25, wherein the filling material is a crushable insulating material. 28. The surge arrester of claim 21, wherein the housing encloses at least a portion of the terminal and encloses the stack with an interference fit. 29. The surge arrester of claim 21, wherein an insulative barrier fits around a side of the cylindrical stack of components. 30. The surge arrester of claim 29, wherein the barrier is a thin plastic film. 31. The surge arrester according to claim 21, wherein the filling material forms at least a part of the elastic housing. 32. The surge arrester according to claim 21, wherein the filling material is composed of a crushable resin. 33. The surge arrester according to claim 21, wherein the filling substance is grease.