RU2256972C1 - Surge limiter - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: proposed surge limiter designed for . protection of high-voltage equipment insulation of power networks and stations against atmospheric and short-time switching surges has at least one module incorporating base insulating tube of composite material faced by tracking-protective ribbed cover, metal electrodes secured at its ends, and axially held-down varistor disk column placed in-between. Base tube is fixed to metal electrodes through pin joint; varistor column is coaxially locked in position within base tube by means of net sleeve. Base insulating tube may be made of composite fibrous material or glass-fabric laminate. Net sleeve may be made of continuous spiral threads and also of continuous thermosetting threads, or of continuous threads such as aramide ones. Flexible current-conducting compensating disk may be made of metal-filled rubber.

EFFECT: improved design.

12 cl, 9 dwg

Description

The invention relates to electrical engineering, in particular to devices for protecting the insulation of high-voltage equipment of electrical networks and stations from atmospheric and short-term switching overvoltages.

A device for surge protection, containing a varistor column located between the two end electrodes in an insulating frame located in the outer polymer shell with ribs. The insulating frame contains at least three longitudinal stiffeners made of fiberglass, connected by jumpers forming on the side surface of the window frame, while the frame is equipped with an elastic shell made, for example, of silicone rubber [1].

A disadvantage of the known device is its low rigidity and bending strength, which significantly limits the permissible safe height of the structure of the supporting surge suppressor, and therefore, the long-term allowable operating voltage of such devices. The longitudinally oriented fiberglass in the longitudinal stiffeners of the insulating frame under the influence of wind load or tensile forces lose stability, which leads to an increase in the bending movements of the frame, to undocking the varistor disks and to reduce the protective and resource characteristics of the limiter. Increased bending movements of the frame contribute to the delamination of the silicone elastic shell from the surface of the fiberglass stiffeners and the formation of internal longitudinal leakage channels with a minimum creepage distance and discharge intervals. In the case of the explosive nature of the destruction caused by the intense influx of thermal decomposition gases of the elastic shell and the polymer insulating body, the probability and danger of radial expansion of the fragments of the destroyed varistor disks are very high.

Also known is a surge arrester [2], adopted as a prototype, which contains a package of several varistor disks mounted one after another in the axial direction between the upper and lower end electrodes and surrounded by an elongated electrical insulating outer casing made of rubber or other polymeric material, moreover, the end electrodes are connected to each other by means of tightening elements in the form of at least three clamps from a continuously wound strand of insulating material to achieve t ebuemogo contact pressure in the varistor disk. The device has an axial rod protruding from the lower end electrode and making contact with the clamping conductor washer, and also contains a screw for creating a preliminary tension in the package of varistor disks. An elastic electrical insulating plate is installed between the pressure plate and the end electrode.

A significant drawback of this device is that when exposed to strong wind loads, tensile forces and other factors causing structural bending, a strong concentration of contact stresses occurs at the edges of the end surfaces of the coupling of the varistor disks, which can cause them to chip or crumple with the resulting negative the consequences. On the other hand, under the action of an external lateral load, the varistor column is subjected to severe lateral shear deformations, which contributes to the delamination of the varistor disks from the insulating rubber or polymer casing and the formation of leakage channels and internal discharge gaps. The flexural rigidity of the design of the spark gap module is ensured by the mechanical properties of the varistor disks, which causes the risk of their destruction under the action of various natural force factors on the device as a whole. Therefore, the ultimate longitudinal dimensions of the arrester modules are substantially limited. When at least one varistor disk is destroyed in an extreme situation, the tension of the tightening clamps drops or disappears altogether. Then there is the danger of breaking off the multi-module structure, and the danger of flying apart fragments of the destroyed varistors and other parts becomes real with a high degree of probability.

The invention is aimed at improving the design and increasing the explosion safety of the surge suppressor. These disadvantages of the known design are eliminated by the fact that the surge suppressor consists of at least one module, which contains a housing insulating pipe made of composite material, lined with a tracking ribbed cover, glass-shaped metal electrodes fixed at its ends with a central threaded hole in the bottom and placed in its cavities are a column of varistor disks joined with preload, grooved with electrodes through a conductive compensation washer; flock-shaped metal electrodes have hubs facing the inside of the cup and form deep annular grooves with its wall, in which the perforated ends of the insulating casing are recessed; in the wall and the hub of each electrode there are radial holes coaxial with the perforations at the recessed ends of the casing pipe, in which the radial pins fastening the electrodes to the casing pipe are placed and fixed; between the conductive compensation washer and the end face of the hub of at least the upper electrode there is an elastic compensation disk of a current-carrying elastic elastic material, the coefficient of thermal expansion of which is higher than that of the composite material of the casing pipe; in the threaded hole of the hub of the upper electrode, a mounting and clamping pin is installed, designed to create and regulate the normalized compressive force of the varistor disks through the current drive compensation washer; in the hub of the electrode, at least one radial hole is made through and threaded, a locking screw is installed in this hole, fixing the position of the mounting-clamping pin and the normalized clamping force of the varistor disks; varistor disks, compensation washers and an elastic compensation disk are centered in a cylindrical axisymmetric column and are rigidly fixed with a radial tension of a mesh sleeve of spiral cross continuous threads, covering with their loop edge formations the radial pins holding the electrodes with the casing pipe, and the mesh sleeve is preferably located inside the casing pipe and the gap between its inner surface and the axisymmetric varistor column is filled with a heat-conducting electron insulating polymer compound.

The casing insulating pipe of the surge organizer module can be made of a composite fibrous material obtained by winding continuous, for example, a glass fiber bundle impregnated with a polymer binder, at an angle +/- (30 ° -60 °), preferably at an angle +/- 45 °, forming at the ends of the loop border for installation in its loops of the connecting pins. The case insulating pipe can be made of stelotextolite obtained by direct winding of a fiberglass impregnated with a polymer binder, and have in the wall a system of unidirectional cuts made at an angle of 45 ° -60 ° to the generatrix. The mesh sleeve can be made of continuous spiral threads forming rhombic cells according to the type of Chebyshev network. The mesh sleeve can be made of heat-shrinkable continuous filaments, the length of which decreases with increasing temperature. Between the filaments of the mesh sleeve and the generators of the varistor disks, as well as the compensation washers, at least one elastic strip of electrical insulating material, such as epoxy fiberglass, is laid. Between the filaments of the mesh sleeve and the generators of the varistor disks and compensation washers, a polymer shell is located, for example, of silicone rubber with a longitudinal or oblique screw, or with a sawtooth section of a cylindrical wall. The mesh sleeve may be made of continuous, for example, aramid yarns, impregnated with a polymer, for example, epoxy binder. Moreover, the loop edge of the mesh sleeve can be made springy from high modulus elastic threads impregnated with an epoxy binder in the form of trapezoidal loop formations. The conductive elastic compensation disk is made of metal-filled rubber, and the metal inclusions are made either of wire or of a tape formed into an elastic helical spiral that extends with its turns onto the end surfaces of the metal-rubber disk, or in the form of a corrugated tape rolled into a ring and protruding corrugated vertices on end surfaces of the compensation disk forming a system of contact electric drive points.

The technical result obtained by carrying out the invention is expressed in the following:

- significantly increases the reliability, strength, rigidity and explosion safety of each unit module and the universal prefabricated design of the surge suppressor as a whole;

- significantly simplifies the design of the modules of the universal prefabricated surge suppressor and their connections in the prefabricated structure;

- the manufacturability of the component parts of the modules and their connecting nodes is increased, the assembly of the modules and the multi-module surge suppressor is greatly simplified;

- the resource of trouble-free operation in extreme conditions increases due to a significant reduction in the bending movements of the casing insulating pipe and varistor column and by preventing the angular opening of the end joints of adjacent varistor disks due to the elastic-elastic possibility of their transverse shear, which reduces the likelihood of brittle edges of varistors ;

- creates the possibility of reusing modules and connecting elements of universal prefabricated surge arresters after they fail under extreme conditions and restore their functioning by shunting a failed module or by replacing it with a conditioning module;

- the breakdown and expansion of metal electrodes, varistor disks or their fragments and other structural elements in case of an electric arc ignition in a varistor column under extreme operating conditions is completely eliminated due to the shock-absorbing and damping behavior of the mesh sleeve and the casing insulating pipe, the wall of which leads to a sharp increase in internal pressure itself like a tensile coil spring, forming helical spiral bundles of the wall, providing emergency safe discharge inside pressure and energy absorption of compressed gas.

The invention is illustrated in the drawing, where Fig. 1 shows a device of a universal-combined construction of a surge suppressor and its unit module in a section; figure 2 illustrates the centering diagram of the varistor disks and the axisymmetric arrangement of the varistor column in the housing of the surge suppressor module using a mesh sleeve during axial compression of the varistor disks in the column.

Figure 3 shows the spring loop loop of the mesh sleeve formed by the trapezoidal loop formations of continuous turns of high modulus filaments. Figure 4 and figure 5 shows the options for an elastic conductive compensation disk made of metal-filled rubber, in which the metal inclusions are made respectively in the form of a helical wire spiral and in the form of a corrugated tape rolled into a ring. Figure 6 illustrates a variant of axisymmetric centering of the varistor disks with the help of a base strip guide made of elastic electrical insulating material, orienting the varistor disks during their compression and radial alignment with respect to the rectilinear generatrix of the varistor column, adopted as a design and technological base.

Figures 7, 8, 8, 9 respectively show axisymmetric centering and forming a varistor column of a surge suppressor module using an elastic shell made of electrical insulating material with a longitudinal rectilinear section, spiral-helical and sawtooth, used as structural and technological base elements .

Positions in the drawings: 1 - module of a multi-modular multi-module surge suppressor; 2 - supporting base flange; 3 - a coupling made of an electrically insulating tracking material; 4 - toroidal screen; 5 - terminal; 6 - a nut; 7 - case insulating pipe; 8 - tracking protective ribbed tire; 9 - metal cup-shaped electrodes; 10 - radial pins; 11 - varistor disks; 12 - mounting and clamping pin; 13 - conductive compensation washer; 14 - locking screw; 15 - friction liner; 16 - elastic compensation disk; 17 - mesh sleeve; 18 - molded conductive wire helix; 19 - molded conductive metal ring of corrugated tape; 20 - elastic insulating guide strip; 21 - centering shell of insulating material with a longitudinal slot; 22 - centering shell with spiral helical slot; 23 - centering shell with a sawtooth slot.

Overvoltage limiter (Fig. 1) is a universally-assembled design consisting of docked coaxially autonomous modules 1, the lower of which is installed and fixed in the glass of the supporting base flange 2, connected to each other by connecting couplings 3.

A toroidal shield 4 is mounted and fixed on the upper metal cup-shaped electrode of at least the upper module, and the connecting terminal 5 is fixed on the upper electrode with the nut 6.

A sectional stand-alone surge suppressor module is shown in FIG. 1 and consists of a housing insulating pipe 7 made of composite material, for example, fiberglass, lined with a tracking ribbed cover 8, at the ends of which are installed upper and lower metal glass-shaped electrodes 9, identical in design. Between the wall and the hub of each electrode 9 there is a deep annular groove; the ends of the casing pipe 7 are recessed in the grooves. The electrodes 9 are connected to the casing pipe 7 by a system of radial pins 10 installed in the holes of the electrodes and the pipe on a sealant or on an adhesive, for example, epoxy. In the cavity of the casing pipe 7, a column of varistor disks 11 is arranged coaxially, joined by end surfaces and pressed against each other by a mounting-clamping pin 12, through a conductive compensation washer 13.

The normalized clamping force of the varistors by the pin 12 is fixed by the locking screw 14 through the friction liner 15. Between the upper electrode 9 and the conductive compensation washer 13 there is an elastic compensation disk 16 made of conductive elastic material, the coefficient of thermal expansion of which is higher than that of the case pipe material. The column of varistor disks 11 is assembled in a mesh sleeve 17 (Fig. 2), the loop formations of the upper and lower rims of which are fixed on the pins 10, fastening the electrodes 9 with the casing pipe 7.

To increase the springy properties of the mesh sleeve, providing radial compression and centering of the varistor column, the loop edge of the mesh sleeve can be formed by trapezoidal loop formations (figure 3).

The elastic compensation disk 16 is made of a conductive material, for example, of rubber, that is, rubber filled with a conductive metal filler, in particular in the form of a continuous wire helical spiral 18, acting as the arcs of its turns on the end surfaces of the conductive compensation disk (Fig. 4), or in the form of a corrugated tape rolled into a ring 19, molded into a rubber disk 16 and protruding with the tops of its corrugations on the end surfaces of the disk (Fig. 5). To simplify and improve the accuracy of assembly and centering of the varistor column in the module housing pipe, a design variant with an elastic guide strip 20, for example, of fiberglass, forming a rectilinear generatrix of the varistor column parallel to its axis (Fig. 6), or a centering shell variant with a longitudinal slot 21 (Fig. 7), either with a spiral-helical slot 22 (Fig. 8), or with a sawtooth slot (Fig. 9).

The casing insulating tube 7 can be made of epoxy fiberglass by spiral cross winding continuous glass fiber bundle or thread impregnated with epoxy binder at angles to the generatrix in the range +/- (30 ° -60 °). it is desirable that the spiral coils of the threads at the ends of the pipe be laid with loop arcs forming radial holes for the pin connection of the housing pipe with metal electrodes.

The body tube can be made of fiberglass by direct winding of fiberglass impregnated with an epoxy binder. In this case, the radial holes for the pin connection are performed by machining, and the spring and cushioning and damping properties of the casing pipe are provided by a system of unidirectional spiral-helical slots in the glass-fiber wall at angles of 30-60 °, preferably at an angle of 45 °.

The internal cavities between the varistor disks, centering shells and the casing insulating tube are filled with a heat-conducting insulating compound, in particular an organosilicon composition.

An elastic conductive metal-rubber compensation disk provides shunting of the upper electrode of the module through a compensation washer with a varistor column and significantly increases the heat sink and dissipation of heat generated by the varistors through the metal, in particular aluminum, electrodes of the surge arrestor modules. With intense heat generation, the rubber base of the elastic compensation disk, which has a higher coefficient of thermal expansion than the composite material of the casing pipe, increases in volume and compensates for the thermoelastic increase in the size of the casing pipe, while maintaining and even increasing the hydrostatic compression of the varistor disks in the module column, and due to the hydrostatic effect volume compression prevents wedging of the end-joined surfaces of adjacent varistor disks under the action of external bending loads.

The modular design of the surge suppressor can significantly reduce the length of the casing insulating pipe of each module and, thus, reduce its bending deformations under the influence of external wind loads, tensile forces, icing, etc., and significantly increase the rigidity of the multi-module construction compared to traditional limiter options foaming due to the presence of rigid docking assemblies fastened with metal electrodes of modules like a bamboo tree trunk. At the same time, the presence of an elastic rubber-metal compensation disk helps to create conditions under the curvature or ovalization of the module casing pipe under which the ends of adjacent varistor disks do not wedge but move along each other in the direction of bending, without losing electrical contact and without interfering with heat exchange processes between them.

Under extreme conditions, with powerful lightning or switching overloads leading to internal arc discharges and the explosive nature of the influx of arc gases of thermal destruction of materials in one or another module of a multi-module prefabricated surge arrester, the metal electrodes of this module, like a plunger or piston, move telescopically along the axis, loading in the longitudinal the direction of the fiberglass wall of the module housing pipe, which due to the spiral-helical conformation of the glass fibers in the structure due to spiral slits in the fiberglass wall, tenks are deformed during longitudinal tension like a helical spring, forming through spiral spiral cracks or crevices in the fiberglass wall, through which hot gases escape outside, relieving the internal pressure inside the casing, behaving like a classic shock-absorbing damping a system operating in an autoregulated mode, absorbing and dissipating the elastic energy of a compressed gas and the energy of elastic deformation of structural elements module.

The presence of a mesh sleeve, a centering shell, and a spring-like cracked depressurized fiberglass case pipe, firmly and reliably fastened with pins with end electrodes of the module, multistage and reliably eliminates the possibility of an explosive nature of the destruction of the module with expansion of solid damaging fragments and parts, as well as an elastic shock wave.

Since in extreme conditions it is practically possible to destroy only one module of a prefabricated multi-module surge suppressor, it becomes possible to quickly repair a damaged, that is, a failed surge suppressor without dismantling and replacing it. It is enough to remove the burned-out limiter module, and install a new air conditioning module in its place, or instead of the burned-out module, install an intermediate sleeve and shunt the electrodes of two adjacent modules in the formed electric circuit connector, or simply pull and fasten the electrodes of two neighboring modules, eliminating the formed zone of the connector.

Sources of information

1. RU, patent No. 2172035. Device for surge protection.

2. RU, patent No. 2145743. Surge arrester.

Claims (12)

1. Surge suppressor, consisting of at least one module containing a housing insulating pipe made of composite material, lined with a tracking protective rib cover, glass-shaped metal electrodes fixed at its ends with a central threaded hole in the bottom and a column docked with compression placed in its cavity varistor disks, grooved with electrodes through a conductive compensation washer, characterized in that the glass-shaped metal electrodes have steps The tubes facing the inside of the cup and forming deep annular grooves with its wall, in which the perforated ends of the housing insulating pipe are recessed, have radial holes in the wall and hub of each electrode, which are aligned with each other and with perforation holes on the recessed ends of the housing pipe, in which fixed radial pins holding the electrodes to the body pipe; between the conductive compensation washer and the end face of the hub of at least the upper electrode there is an elastic compensation disk made of conductive elastic material, the coefficient of thermal expansion of which is higher than that of the composite material of the casing pipe; in the threaded hole of the hub of the upper electrode, a mounting and clamping pin is installed, designed to create and regulate the normalized compression force of the varistor disks through a conductive compensation washer; in the electrode hub, at least one radial hole is made through and threaded, a locking screw is installed in this hole, fixing the position of the mounting-clamping pin and the normalized clamping force of the varistor disks; varistor disks, compensation washers and an elastic compensation disk are centered in a cylindrical axisymmetric column and are rigidly fixed by a radial interference of a mesh sleeve of spiral cross continuous filaments, covering radial pins fastening electrodes with a housing pipe with their loop edge formations, and the gap between its inner surface and axisymmetric the varistor column is filled with a thermally conductive insulating compound. 2. The surge suppressor according to claim 1, characterized in that the casing insulating pipe of the limiter module is made of composite fibrous material obtained by winding a continuous fiberglass strand impregnated with a polymeric binder at an angle +/- (30-60 °) forming at the ends loop formations for installation of connecting pins in them. 3. The surge suppressor according to claim 1, characterized in that the casing insulating pipe is made of fiberglass, obtained by direct winding of a fiberglass impregnated with a polymer binder, and has a system of through unidirectional cuts made at an angle to the generatrix in the wall. 4. The surge protector according to claim 1, characterized in that the mesh sleeve is made of continuous spiral threads forming rhombic cells fastened at the intersection points of the spirals. 5. The surge suppressor according to claim 1, characterized in that the mesh sleeve is made of heat-shrinkable continuous threads, the length of which decreases with increasing temperature. 6. The surge arrestor according to claim 1, characterized in that at least one elastic strip of electrical insulation material, such as epoxy fiberglass, is laid between the filaments of the mesh sleeve and the generators of the varistor disks and expansion washers. 7. The surge suppressor according to claim 1, characterized in that between the filaments of the mesh sleeve and the generators of the varistor discs and compensation washers is a polymer shell made of organosilicon rubber with an oblique helical section through a cylindrical wall. 8. The surge suppressor according to claim 7, characterized in that the polymer shell has a sawtooth section of a cylindrical wall. 9. The surge suppressor according to claim 4, characterized in that the mesh sleeve is made of continuous aramid yarn impregnated with a polymer binder, for example epoxy. 10. The surge suppressor according to claim 1, characterized in that the looped border of the mesh sleeve is made springy of modular elastic threads impregnated with an epoxy binder in the form of trapezoidal loop formations. 11. The surge suppressor according to claim 1, characterized in that the conductive elastic compensation disk is made of metal-filled rubber, and the metal inclusions are made of either wire formed into an elastic helical spiral that extends with its turns to the end surfaces and forms a system of contact conductive points. 12. The surge suppressor according to claim 11, characterized in that the metal inclusions are made in the form of a corrugated tape rolled into a ring and protruding by the corrugation vertices on the end surfaces of the elastic compensation washer.

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