1363results about "Insulating bodies" patented technology

The invention relates to the technical field of high-voltage electrical equipment, and particularly discloses a high-insulating-property thermoplastic sleeve and a method for preparing the same based on a co-extrusion process, the surface of a nonlinear layer is wrapped with an insulating material, so that the corona discharge phenomenon is avoided; and meanwhile, the same thermoplastic material is adopted as the insulating layer (including the first thermoplastic layer and the second thermoplastic layer) material and the base material of the nonlinear layer, so that no obvious interface exists between the insulating layer and the nonlinear layer, charge accumulation is avoided, insulation failure is avoided, the insulation and voltage resistance of the sleeve is improved, and the operation reliability is improved.

The present application discloses a back-contact cell and photovoltaic module. The back-contact cell includes a cell body, including a first surface and a second surface arranged opposite to each other; a plurality of first fine grids and a plurality of second fine grids arranged on the first surface; the first fine grids and the second fine grids extend along the first direction and are alternately spaced in sequence along the second direction; the first direction intersects the second direction; a plurality of first insulating blocks are spaced along the second direction and respectively cover the second fine grids; along the second direction, the distance between the edges of adjacent first insulating blocks is D1, and D1 ≥ 80 μm. The distance between two adjacent first insulating blocks along the second direction is large enough, so that a safe distance for the slurry to flow is reserved, thereby avoiding the situation where the slurry forming the first insulating block flows and covers the first fine grid, ensuring the stability of the electrical connection between the first fine grid and the first conductive member, and thus improving the stability of the back-contact cell performance.

The high-performance insulation blanket comprises a surface layer, an EVA adhesive layer and a surface layer which are sequentially arranged, and the surface layer and the EVA adhesive layer are attached in a calendering mode; the surface layer is prepared from the following raw materials in parts by weight: 45 to 55 parts of ethylene-vinyl acetate copolymer, 10 to 20 parts of natural rubber, 8 to 18 parts of PA6 short fiber, 7 to 10 parts of dopamine modified mica powder, 6 to 10 parts of MAH-g-EVA, 10 to 15 parts of flame retardant, 0.2 to 0.4 part of antioxidant, 0.8 to 1.2 parts of lubricant and 2 to 4 parts of coloring agent. In the surface layer formula system, under the synergistic effect of the natural rubber, the PA6 short fiber and the dopamine modified mica powder, the tear resistance and puncture resistance of the material are greatly improved, and meanwhile, the material has excellent comprehensive properties such as high temperature resistance, insulation, flame retardance and aging resistance, and is suitable for the field of high-requirement insulation protection.

The utility model is suitable for the technical field of main-grid-free back contact cells, and provides a main-grid-free back contact cell, a cell assembly and a photovoltaic system. The main-grid-free back contact battery comprises a main grid line area and a plurality of edge grid line areas, wherein the main grid line area is positioned between two edge grid line areas; the fine grid in the edge grid line area is provided with a plurality of first insulating glue and a plurality of first connecting structures, the first connecting structures electrically connect the fine grid with the welding strip, and the first insulating glue electrically isolates the fine grid from the welding strip; wherein the area of the single first insulation paste is larger than that of the single first connection structure. According to the main-grid-free back contact battery, the area of the first insulation paste in the edge grid line area is larger than the area of the first connection structure, so that larger electrical isolation is provided for the grid lines and the welding strips in the edge grid line area, the short circuit problem is prevented, and the effect of improving the stability of the main-grid-free back contact battery is achieved.

The invention provides a power assembly and a motor controller, the power assembly comprises a power module, a radiator and an insulating part, the power module comprises a leading-out terminal, the insulating part is arranged on the surface of one side, facing the power module, of the radiator, and in the thickness direction of the power assembly, the projection of the insulating part covers the projection of the leading-out terminal on the radiator; the projection of the leading-out terminal on the radiator is covered by the projection of the insulating part in the thickness direction of the power assembly, the safety electrical insulation between the leading-out terminal and the radiator is ensured through the insulating part, and the electrical insulation performance between the power module and the radiator is improved.

The invention relates to the technical field of high-voltage bushings, in particular to a 72.5 kV impregnated paper high-voltage bushing which comprises a sheath layer, an insulation paper layer, an impregnation medium, a flexible supporting structure, a temperature control layer, a self-healing insulation medium and a connecting end. The sheath layer is made of aluminum alloy and is used for providing mechanical protection and support; the insulation paper layer adopts multi-layer high-elasticity polyester impregnated paper, so that excellent electrical insulation performance is provided; the impregnation medium is selected from nano reinforced silicone oil and is uniformly filled between the insulation paper layers, so that the insulation performance is enhanced, and the moisture-proof and anti-pollution capacities are improved. The flexible supporting structure comprises a honeycomb-shaped FRP supporting layer and a shape memory alloy connecting piece, mechanical stress generated in transportation, installation and long-term operation can be effectively absorbed, and the structural integrity is kept under the complex environment such as foundation settlement or temperature change. The high-voltage cable has the advantages of high insulating property, high mechanical strength, excellent environmental adaptability and self-repairing capability, is suitable for transformer substations, power transmission lines and other high-voltage electrical equipment, and has wide application prospects.

The invention discloses an electric lightning arrester insulation shield capable of being installed without power outage and an installation method, and relates to the technical field of electric protection, the electric lightning arrester insulation shield comprises an insulation cover, an elastic automatic locking mechanism, an installation sheet and a reinforcing plate, the insulation cover is integrally formed, a turnover plate is connected to the lower ends of a left side plate and a right side plate, and the elastic automatic locking mechanism comprises a left locking module and a right locking module; the modules are connected through a pressure piece and a clamping piece through a connecting piece, a lock body part penetrates through a locking hole to achieve locking, during installation, the protective cover is driven by an insulating rod to be horizontally pushed into the top of the lightning arrester, a locking mechanism is extruded and triggered to achieve automatic locking, the protective cover is fixed to an exposed metal piece, and main insulation is not affected. Locking is reliable, the service life is long, operation is convenient, the device can be expanded to multiple fields, and safe operation of equipment is guaranteed.

The invention relates to a magnetic attraction insulation shield capable of being installed without power cut, which comprises a shell, the shell comprises a left shell and a right shell, the top end of the left shell is connected with the top end of the right shell, the upper parts of the left shell and the right shell are respectively provided with a connecting buckle, the connecting buckles are fixed on the surface of the left shell or the right shell, a connecting rope is also arranged above the shell, and the connecting rope is connected with the left shell and the right shell. One end of the connecting rope is connected with the connecting buckle on the surface of the left shell, the other end of the connecting rope is connected to the connecting buckle on the surface of the right shell, and the shells, the connecting buckles and the connecting rope are all made of insulating materials. The magnetic attraction insulation shield installed in an electrified mode is convenient and easy to install and high in efficiency.

The utility model relates to the technical field of solar cells, and particularly discloses a back contact cell assembly and a photovoltaic system, the cell assembly comprises a cell substrate, the back surface of the cell substrate is provided with a first grid line and a second grid line which are arranged in a staggered manner along a first direction and have opposite polarities; the confluence pieces comprise first confluence pieces and second confluence pieces, the first confluence pieces and the second confluence pieces are arranged in a staggered mode in the second direction, the first confluence pieces are electrically connected with the first grid lines, and the second confluence pieces are electrically connected with the second grid lines; the bus bar is electrically connected with the first bus member, and an insulating block is arranged between the bus bar and the second bus member; the insulating glue layer is arranged between the second grid line and the first bus piece, and in the second direction, the insulating glue layer comprises a first insulating part which continuously extends from the first bus piece to the direction of the adjacent second bus piece, and in the second direction, the insulating glue layer comprises a second insulating part which continuously extends from the second bus piece to the adjacent second bus piece; the sum of the distance from one end, away from the second bus piece, of the insulating block to the second bus piece and the width of the first insulating part is larger than the distance between the adjacent first bus piece and second bus piece. The reliability of the battery assembly can be improved, and meanwhile the production difficulty is reduced.

Device comprising at least a top-side hood (10) for receiving an electrical component, such as a terminal block, for attaching at least one electrical conductor, and a bottom-side base (14) which is provided with a bottom-side opening (16) for receiving another electrical component, such as an insulating candle, which can be electrically connected to the first electrical component, characterized in that the hood (10) and the base (14) are two separable components which, when assembled, form a cover (18) as a whole and which, by means of a height adjustment (20) with a locking device, assume such different positions relative to each other that differently designed electrical components in a predefinable mounting frame can be covered with only one cover (18).

The invention relates to the technical field of fluorosilicone materials, in particular to a glass fiber sleeve with an excellent voltage resistance function and a preparation method of the glass fiber sleeve. The glass fiber sleeve with the excellent voltage-resistant function comprises a glass fiber sleeve and a composite coating coated on the outer side of the glass fiber sleeve, the composite coating is obtained by thermocuring a coating material; the coating material is prepared from the following raw materials in parts by mass: 50 to 100 parts of fluorinated silicone rubber emulsion, 1 to 5 parts of bis (3-aminopropyl) terminated polydimethylsiloxane, 0.5 to 1.5 parts of furfuryl alcohol resin, 1 to 5 parts of epoxy resin, 1 to 5 parts of activated nano silicon dioxide, 1 to 3 parts of boron nitride nanowire, 1 to 2 parts of dopamine hydrochloride, 1 to 2 parts of dispersing agent and 10 to 30 parts of solvent. The invention can effectively ensure that the coating forms a compact cross-linked structure in the curing process, and can enhance the adhesive force of the coating, weaken the temperature difference between the surface and the interior, inhibit the heat accumulation effect and delay the degradation of the insulating property.

The utility model provides an electronic device which comprises a first structural member and a second structural member, the first structural member comprises a first metal matrix, the second structural member comprises a second metal matrix and a decoration layer arranged on one side of the second metal matrix, and the first metal matrix is electrically connected with the second metal matrix. The corrosion potential of the first metal matrix is lower than that of the second metal matrix; an insulating layer is further arranged on the side, away from the second metal base body, of the decorative layer, the insulating layer is a transparent or semitransparent layer, and the impedance of the insulating layer is larger than or equal to 2000 ohms. The insulating layer is arranged on the decorative layer on the second metal matrix with high corrosion potential, so that a potential difference caused by a closed loop formed between the metal matrixes with different chemical activities can be prevented in a sweat environment or a salt mist environment, and the probability of electrocorrosion of the first metal matrix with low corrosion potential is further reduced; and the long-term use requirement of the electronic equipment is well met.

A novel inclined sleeve structure for a 126kV GIS is characterized in that the upper part of a transition tank body is provided with three flange ports, each flange port is provided with an insulating sleeve, and the installation angle of the three insulating sleeves and the vertical direction form an angle of 30 degrees or 60 degrees; three conductors are arranged in the transition tank body, each conductor is formed by integrally casting a contact and a bent rod conductor, the three conductors are respectively arranged along the axes of the three flange ports, and a guide piece is arranged at the upper end of each conductor; a conducting rod is arranged in the insulating sleeve, one end of the conducting rod is installed in a contact of the conductor through a guide piece in the axis direction of the insulating sleeve, and the other end of the conducting rod is fixedly installed on a conducting end cover at the end of the insulating sleeve through a disc spring and a bolt. Through the structure, the utility model provides the novel inclined sleeve structure for the 126kV GIS, which can reduce the equipment size, reduce the equipment cost and reduce the manufacturing cost of a transformer substation.

An improved telegraph pole double-porcelain-bottle anti-bird hard insulating sheath capable of being installed in an electrified mode comprises two porcelain bottle sleeves used for wrapping the tops of porcelain bottles, one side of each porcelain bottle sleeve is provided with an outer side electric wire sleeve used for wrapping an electric wire, and the other side of each porcelain bottle sleeve is provided with telescopic electric wire sleeves which are in butt joint with each other and are symmetrical to the outer side electric wire sleeves. The lower end of the porcelain insulator sleeve is provided with an opening corresponding to the upper part of the porcelain insulator, the lower edge of the outer wire sleeve and the lower edge of the telescopic wire sleeve are provided with a slit communicated with the opening at the lower end of the porcelain insulator sleeve, and the two edges of the slit are respectively provided with a butt joint edge extending downwards; a mounting plate is arranged on each porcelain insulator sleeve, and a mounting hole is formed in each mounting plate; the opposite sides of the two butt joint edges are connected with clamping plates through elastic bodies respectively. The insulating sheath is made of a hard insulating material. The utility model has the advantages that the wire clamp can be suitable for wires with larger or smaller diameters, the applicability is greatly improved, the requirement on the elasticity of raw materials is reduced, and the wire clamp can be made of harder insulating materials.

The utility model discloses a wall bushing, which comprises a connecting bushing and porcelain bushings arranged at two end parts of the connecting bushing, the connecting bushing comprises a connecting seat and a connecting flange, one end of the connecting seat is provided with the connecting flange, the connecting flange is sleeved on the surface of one porcelain bushing, and the other end of the connecting seat is connected with the connecting flange. And the connecting seat is arranged between the connecting parts of the two porcelain bushings. In combination with the structural design of the utility model, through the arrangement of the connecting seat, the function of splicing and connecting two porcelain bushings can be realized, and the problem that only the damaged porcelain bushing needs to be replaced when one porcelain bushing is damaged in the use process is effectively solved, so that the use cost is reduced, and the practicability is better.

The invention relates to an adhesive technology based on a laminated spraying copper bar, and belongs to the technical field of copper bar production technologies, and the adhesive technology comprises the following steps: copper bar pretreatment: carrying out processing treatment on the copper bar according to the structural requirements of a design drawing; gluing and laminating are conducted, specifically, the surface of the spraying copper bar 1 and the surface of the insulating plate 2 are evenly smeared with adhesives, the adhesives are placed in an overlapped mode according to design requirements, and the adhesives make contact with one another and are tightly attached to one another; curing treatment is conducted, specifically, the stacked copper bars are put into a drying oven to be subjected to curing treatment; and in the performance test process, the sprayed copper bar is subjected to voltage withstanding alternating current for 10kv for 60s, so that no breakdown and no flashover are realized, and the partial discharge value is less than or equal to 10pC. The insulating plate needs to be selected with proper thickness and size according to electrical performance such as creepage distance and the like. The spraying thickness of the epoxy resin coated copper bar needs to be controlled according to insulation performance and the like. The finished adhesive copper bar has good electrical and insulating properties, and meets the requirements of the power industry for high-performance conductive parts.

The invention provides a button type signal feed-through for a beam position detector. The button type signal feed-through comprises a shell, a composite unit and an insulator. The composite unit comprises a button electrode and an inner conductor, and the button electrode is suitable for sensing an electromagnetic field signal generated by charged particle beams in the vacuum cavity; the inner conductor vertically and integrally extends from the center of the button electrode, a flange is arranged near one end, close to the button electrode, of the inner conductor, and the inner conductor is suitable for transmitting beam electromagnetic field signals. The insulator is sleeved on the inner conductor and comprises a first section cylinder and a second section cylinder, and the front end face of the first section cylinder is welded and fixed with the flange of the inner conductor; the second section of cylinder body extends outwards in the radial direction from the rear end of the first section of cylinder body, the circumferential outer surface of the second section of cylinder body is welded and fixed with the shell, and the insulator is suitable for fixed support and electrical insulation, so that smooth transition of transmission impedance and vacuum sealing are realized. The invention further provides a preparation method of the charged particle beam position detector and a charged particle beam position detector structure.

The invention discloses a collector ring inter-ring insulation device and a collector ring, and belongs to the technical field of power generation equipment, the insulation device comprises an insulation column arranged between an upper ring and a lower ring, the insulation device is characterized in that the insulation column is of a sectional structure, and the insulation column comprises an upper insulation column and a lower insulation column; a middle insulating ring plate is arranged between the upper insulating column and the lower insulating column, the diameter of the upper insulating column is the same as that of the lower insulating column, and the inner side and the outer side of the middle insulating ring plate extend out of the lower insulating column. According to the insulation device, through multi-layer insulation design and mechanical cooperation, the creepage distance can be effectively increased, and the insulation performance is remarkably improved.

The present invention relates to an insulated rolling bearing in which a molded resin (5) has: an outer peripheral insulating part (5a) that covers the outer periphery of an outer ring (1); an end surface insulating portion (5b) covering an axial end surface (6) of the outer ring (1); and an end portion inner peripheral insulating portion (5c) extending axially inward from the radially inner end of the end surface insulating portion (5b) and entering the molded recess (8), the portion of the recess side surface (13) of the molded recess (8) covered by the end portion inner peripheral insulating portion (5c) being formed as an inclined surface having an inclination that is displaced axially outward toward the radially inner side.

The invention discloses an oil-immersed transformer low-voltage side sleeve insulating protective cover device which comprises a protective assembly, a fixed part, a first sliding part and a second sliding part, and the fixed part, the first sliding part and the second sliding part are arranged outside the low-voltage side of a transformer in a sleeving mode. The fixing part, the first sliding part and the second sliding part are each provided with an outer convex face used for protection and an inner concave face facing the low-voltage side of the transformer, and the first sliding part and the second sliding part are arranged close to one side of the inner concave face of the fixing part and can slide along the inner concave face of the fixing part. The oil-immersed transformer protection device has the beneficial effects that protection operation on the low-voltage side of the oil-immersed transformer is achieved through cooperation of the fixed part, the first sliding part and the second sliding part, and by means of the characteristic that the first sliding part and the second sliding part can slide freely, workers can directly open the placement interval when the transformer is overhauled or maintained, and the operation is convenient. The operation of dismounting the insulating sleeve in the traditional maintenance work is avoided, and the maintenance efficiency is greatly improved.

The utility model provides an outdoor energy storage power supply capable of being wirelessly charged, the outdoor energy storage power supply capable of being wirelessly charged comprises a shell assembly, a support assembly, an inverter module, a wireless charging module and a shielding cover assembly, the shell assembly is provided with a containing groove, the support assembly is installed in the containing groove, the inverter module is installed on the support assembly, and the wireless charging module is installed in the containing groove. The shielding cover assembly comprises an outer insulating layer, a metal shielding heat dissipation layer and an inner insulating layer which are sequentially arranged in a covering mode, the inverter module is covered with the inner insulating layer, the metal shielding heat dissipation layer is connected to the support assembly and corresponds to the air channel of the shell assembly, and the wireless charging module is arranged on the face, away from the metal shielding heat dissipation layer, of the outer insulating layer. The metal shielding heat dissipation layer shields an electromagnetic field, the problem of mutual interference between the inverter module and the wireless charging module is solved, the metal shielding heat dissipation layer is insulated from the inverter module and the wireless charging module, the metal shielding heat dissipation layer is good in heat conductivity, the ventilation and heat dissipation effects are improved, and the safety performance of the energy storage power supply is improved.

The embodiment of the invention provides an insulating film and a preparation method thereof, an insulating composite film and a preparation method thereof, and electrical equipment, and relates to the technical field of expansion materials. The insulating film comprises a fiber matrix and an expansion compound, and the expansion compound is compounded in the fiber matrix. The insulating film can be prevented from being separated or cracked, and the electrical property and the mechanical property of the insulating film are improved.

The invention discloses a corona-resistant ceramic composite insulating material as well as a preparation method and application thereof, and belongs to the technical field of high-performance composite insulating materials and preparation thereof. The problems that an existing insulating material is insufficient in corona resistance and difficult in powder doping are solved. BMI-DBA is used as a functional carrier to load ADP powder to obtain a BD-A system, the BD-A system is further compounded with PI by adopting a cospinning process, and after imidization treatment, the composite insulating material with remarkable corona resistance is obtained. Through PI and BD-A system co-spinning and imidization treatment and in combination with an ADP ceramization process, the corona resistance of the composite insulating material is remarkably improved. Experimental results show that the corona resistance time of the composite material reaches more than 650 hours, and is improved by more than 6500 times compared with that of a pure PI insulation paper material (about 0.1 hour).

A grommet includes an umbrella-shaped member that is separate from a grommet body. The umbrella-shaped member has a covering portion that covers an insertion hole of a sound insulator provided on one surface of a vehicle body panel. The covering portion is inclined to increase in diameter toward the sound insulator. The grommet body has an engagement portion that axially locks to a front end of the covering portion, which is the front end of the umbrella-shaped member.

According to the invention the Grommet (14) is designed for a wall bushing (2) and for the sealed passage of a strand (12), in particular a cable, through an opening (10) in a wall (4). The wall (4) is especially a wall (4) of a dash panel of a motor vehicle. The grommet (14) having a grommet body (16) which extends in an insertion direction (E) and which has a proximal sealing section (18) and a distal sealing section (20), which, in the assembled state, receive the wall (4) between them, wherein the distal sealing section (20) is corrugated in the circumferential direction so that it is compressible and can be inserted through the opening (10) in the insertion direction (E). Preferably the distal sealing section (20) comprises a cap element (22) having a cap opening (23) and during assembly the grommet is inserted through the opening (10), while the cap opening (23) is oriented in the insertion direction (E). Afterwards the cap element (22) is folded over such that the cap opening (23) is oriented towards the wall (4) and a distal sealing lip (24) rests on a distal wall side (4B).

The utility model relates to a high-performance controller device for an electric bicycle, which comprises a hollow outer wrapping body, a control module, a conductive column module and a power module are assembled in the outer wrapping body, and the bottom end surface of the power module is attached to the inner bottom wall surface of the outer wrapping body; the conductive column module structurally comprises a mounting support, a plurality of first binding posts, a plurality of second binding posts and a plurality of supporting rings are fixed to the end face of the mounting support at intervals, the first binding posts are used for being connected with a driving power source, and the second binding posts are used for being connected with a motor. The support ring is arranged between the control module and the power module so as to separate the control module from the power module. By arranging the conductive column module, the control module and the power module can be separated, so that the power module can be mounted in a manner of being attached to the inner bottom wall surface of the outer wrapping body, the layout is compact, meanwhile, the heat dissipation efficiency is improved, and the performance of the controller device is improved.

To provide a fixing structure of an insulating sheet in which the number of components and the number of assembling steps are small and fixing force is hardly reduced by heat, vibration, or the like, and to provide an insulating sheet capable of easily achieving the fixing structure of the insulating sheet, and a manufacturing method capable of easily manufacturing the fixing structure of the insulating sheet.SOLUTION: An insulating sheet according to the present invention is an insulating sheet that is fixed to an object to be protected and insulates and protects the object to be protected, the insulating sheet including a flat plate portion that is made of a resin material and extends in a flat plate shape, and a protruding molded portion that is molded so as to protrude in a protruding shape from the flat plate portion, in which an outer surface of the protruding molded portion includes an enlarged diameter portion that is enlarged in diameter from a base end portion toward a tip end portion of the protruding molded portion.SELECTED DRAWING: Figure 1

Systems and methods according to the present invention include a device for delivering non-invasive direct current electricity to the oral cavity of a non-human animal. The device generally comprises layers, wherein an electronic circuit assembly is protected within an enclosure, which itself is protected within a frame. Surrounding the frame, a plurality of traces connect to rails and nubs, which are exposed through the outer mold layer. The rails and nubs act as anodic and cathodic electrodes. When masticated, the non-human animal's mouth (teeth and / or gums) closes the circuit between the anodic and cathodic electrodes, delivering relatively weak direct current electricity to the animal's oral health benefit.

The invention relates to the technical field of high-voltage circuit insulating materials, in particular to a flexible insulating sling for high-voltage operation and a preparation method of the flexible insulating sling. The flexible insulating sling for high-voltage operation sequentially comprises an aramid fiber layer and a polytetrafluoroethylene layer from inside to outside, flame-retardant microcapsules are loaded on the surface of the aramid fiber layer, a core material of each flame-retardant microcapsule is polyphosphate, and a shell material of each flame-retardant microcapsule is acrylic acid modified organic silicon resin. According to the application, the polytetrafluoroethylene and the aramid fiber are compounded to obtain the insulating sling, and the insulating sling is excellent in mechanical property, small in stress deformation, safe and reliable in load bearing, soft in texture, small in bending radius and capable of preventing a hoisted object from being scratched, and the breaking strength of the insulating sling reaches 20-30cN / dtex.

The utility model discloses an insulated intensive bus duct, which comprises a device main body and a separation mechanism arranged in the device main body, the separation mechanism comprises placement bins, sealing plates arranged at two ends of the device main body and heat dissipation plates arranged in the placement bins, and a conductive plate is arranged in each placement bin. The placement bin is used for separately placing a plurality of current-conducting plates, and the heat dissipation plate is used for dispersing heat of the current-conducting plates; according to the utility model, if all the current-conducting plates are in contact, the temperature is further increased, so that a fire behavior is generated in the device main body, and when the plurality of current-conducting plates are separately placed, the influence on the current-conducting plates of other parts is very little when a fire behavior occurs in an independent part; and the placement bin can provide a layer of protection for the whole device main body, so that the fire resistance of the device main body can be improved, and meanwhile, the possibility of mutual power transmission can be reduced to the minimum by separately mounting the conductive plates.