Patent ID: 12206225

DETAILED DESCRIPTION

The electrically conductive surface described herein has been primarily defined in the context of an equipotential zone or EPZ. As defined in the background an equipotential zone is a work area in which a power line worker or other worker is protected from electric shock from differences in electric potential between objects located within the work area. These differences in potential may be caused for example by induced voltage, line re-energization, or lightning. However, as one skilled in the art will appreciate, the electrically conductive surface defined herein may be used in any application which requires formation of a uniform, highly conductive, load-bearing surface

FIGS.1through9illustrate an apparatus10for creating an equipotential zone1on a work area3in the vicinity of an energized power line5(best seen inFIG.7A). The energized power line5includes power transmission lines/conductors7carrying voltages for example in the range of 5 kV to more than 500 kV. In one embodiment and as seen inFIG.1, the apparatus10includes a base member12having an upper layer14and a backing surface layer or ground surface15, which ground surface15is adjacent the ground of the work area3when the apparatus10is positioned on the work area3. The base member12acts as a load-supporting member and is deployed on the work area3for forming the equipotential zone1. The base member12of apparatus10has sufficient mechanical strength to withstand the weight of workers and/or equipment that may be needed within the EPZ. The base member12may be formed of a rigid or flexible material such as wood, aluminum, rubber, plastic, fiberglass, fiber reinforced plastic, high density polyethylene or any combination thereof. In one embodiment and as seen inFIGS.1and1A, the base member12may have a rectangular shape, for example, having dimensions of substantially four feet wide by eight feet long, so that the base member12may be transported and positioned adjacent other base members12with relative ease. The base member12has a pair of opposing short side edges12aand long side edges12b. The upper layer14overlays the base member12and is adapted such that workers or equipment may be positioned on upper layer14. Accordingly, the uppermost surface14aof the upper layer14is substantially flat or planar.

In one embodiment, in order to render the upper layer14conductive, the upper layer14includes an electrically conductive composition, the composition comprising a non-conductive support material13and conductive particles16. In some embodiments and with reference toFIG.1, the conductive particles16may include fine particles; other embodiments (for example,FIG.1A) include conductive particles having dimensions that are two inches or larger. The particles may be in the form of flat flakes of any geometrical shape or may be three-dimensional shapes of any geometry. The size and packing density of the conductive particles16embedded within the upper layer14is such that a continuous electrically conductive path is formed substantially throughout the entirety of the upper layer14, including extension of the continuous electrically conductive path to the surface14aof upper layer14, whereby personnel, tools, and stringing equipment that are positioned on the uppermost surface14aof apparatus10may be electrically connected to the electrically conductive path extending through upper layer14.

In one embodiment the composition of upper layer14may comprise a ratio of at least substantially 2.5 parts conductive particles16, such as for example graphite particles, to one part polyester resin (by volume). The applicant observes that this ratio of composition provides sufficient density of conductive particles16so as to create a uniform conductive surface14asupported by a typically non-conductive support material13. In this example, the composition in its liquid form may be applied over base member12. While a greater ratio of conductive material to resin will increase conductivity of the upper layer14, it may also make the resin, in its liquid form, more difficult to deal with as the mixture becomes more viscous. In the example provided above, the composition in its liquid form is very viscous, like a putty. Testing has shown that the mix ratio in the example above creates a resistivity of approximately +/−-80Ω across the upper layer14. As mentioned previously, the member12may include a commercial mat manufactured of suitable materials for supporting a load, including for example plastic, such as high density polyethylene, fiber-reinforced plastic, or other plastics that are sufficiently strong enough to support the target load and which are preferably lightweight for ease of transportation and manipulation; as well as other materials such as wood, laminate, aluminum, rubber or any other suitable materials known to a person skilled in the art. Although the applicant provides the example of graphite particles as the conductive particles16utilized in the composition referred to above, the conductive particles may include any suitable conductive particles, including and not limited to: graphite or metal shavings, filings or chips; the metal particles may be aluminum, steel, iron or any other suitable metal or any combination of such conductive particles, and also includes any other conductive particles known to a person skilled in the art.

Furthermore, although the applicant provides the polyester resin above as an example of the non-conductive support material13component of the upper layer14, it will be appreciated by a person skilled in the art that other materials may be utilized for the non-conductive support material13, including and not limited to: thermoplastic; plastic and fiberglass composite; fiberglass; rubber; silicone polymer; fiberglass gel coat. It will also be appreciated that various methods may be utilized to form the upper layer14and are not limited to the example provided above of coating the base member12with a liquid composition including the conductive particles16and the non-conductive support material13. Other embodiments described herein teach alternative methods contemplated by the Applicant for forming the upper layer14.

In an alternative embodiment as shown inFIG.3A, the upper layer14comprises one or more conductive elements18partially embedded therein and which extend toward and are partially exposed on the uppermost surface14aof upper layer14. The one or more distributed conductive elements18may be partially embedded in upper layer14in a grid-like pattern so as to create a conductive matrix extending across substantially across its entire surface. The conductive elements form at least a portion of the uppermost surface14aof the upper layer14. As seen inFIG.3A, the grid-like pattern may also extend along the sides of the upper layer14. For example, not intending to be limiting, the conductive elements18may have a thickness in the range of 0.125 inches to 0.375 inches. The conductive elements may also include one or more sheets, rather than a plurality of wires arranged in a grid. The one or more distributed conductive elements18may be constructed from a suitable electrically conductive material such as aluminium, stainless steel, any other metal, or a combination thereof. In another embodiment, the conductive sheet or grid18may include a woven carbon fiber sheet that may be embedded into the uppermost surface18. The carbon fiber sheet may have a thickness in the range of 0.001 inches to 0.125 inches.

In another embodiment, as shown inFIG.3B, the one or more conductive elements18may constitute a layer sandwiched between the base member12and the upper layer14, wherein the upper layer14is a composition of conductive particles16embedded into and distributed throughout a non-conductive support material13, as described above in relation to other embodiments. In these embodiments, the conductive elements18provide an additional layer of conductivity which enhances the overall electrical conductivity of the upper layer14and consequently electrical conductivity of its uppermost surface14a. Advantageously, the layer of conductive elements18may also enhance the electrical connection of a plurality of connected apparatus10so as to provide a substantially uniformly conductive surface across the plurality of connected apparatus10, as further described below.

The base apparatus10further includes or cooperates with at least one grounding element such as a ground rod20and includes at least one bonding cable22(best seen inFIG.14) for connecting the apparatus10, new conductor and stringing equipment S located on the base member12together.

In one embodiment, a larger equipotential zone1′ may be created by interconnecting a plurality of apparatus10, as depicted for example inFIGS.4,7A,7B and14. As shown in the example ofFIG.4, an equipotential zone1′ may be created using four apparatus10which are mechanically and electrically interconnected by a plurality of connector assemblies24along the short and long edges12a,12bof each apparatus10, respectively. The connector assemblies24are made of an electrically conductive material in order to maintain a continuous conductive path between the interconnected apparatuses10. With reference toFIG.5A, in one embodiment, the connector assemblies24include a nut and bolt arrangements and a connecting strap26, wherein for example, each apparatus10includes one or more bores17extending from the uppermost surface14ato the ground surface15of apparatus10. To mount the connector strap26to an apparatus10, a bolt40is journaled through the bore17, the bolt17having for example two washers42,42, wherein each washer42is positioned adjacent to either surface18aor18bof the conductive element layer18. Nut44may be utilized to snugly urge the washer42against the surface18bof conductive element18, on the one side. On the other side, end piece45aof bolt40may include another nut, whereby nut45amay be used to sandwich a strap flange26aof strap26between a washer42and the nut45a, and nut45amay also urge strap flange26aand washer42against surface18aof conductive element layer18. The other end piece45bof bolt40may be a bolt head or may be another nut. The opposing end of strap26(not illustrated) similarly has a flange26awhich is bolted to an adjacent apparatus10utilizing the same or similar bolt40, washers42,42and the nuts45a,44. Advantageously, bolt40, the washers42,42and the nuts45a,44may all be made of metal or other electrically conductive materials, and the arrangement of the connector assembly24as described above and illustrated inFIG.5Amay advantageously enhance the electrical connection between adjacent interconnected apparatuses10,10, as shown for example inFIG.4. In order to further enhance the electrical continuity between adjacent interconnected multiple apparatus10, each apparatus may have a substantially uniform layer of the electrically conductive composition, described above, exposed and extending along its sides (best seen inFIG.6), so that when the sides of adjacent base members abut, electrical conductivity extends continuously across all abutting base members.

FIG.5Billustrates another embodiment of a connector system for interconnecting two adjacent apparatus10. In this embodiment, each apparatus10is provided with alternating or interlocking offset extensions28and recesses30forming a finger-joint along the connecting edges12aor12b. Two adjacent base members12are interlocked by aligning the extensions28and recesses30and press fitting the extensions28into the complementary recesses30. The extensions28are retained in the recesses30by one or more pins or rods31. As the one or more pins or rods31are made of a metal or other conductive material, the one or more pins31also contribute to the enhancement of electrical continuity between the two interconnected apparatuses10. Although a finger-joint is illustrated, it would be understood by one skilled in the art that other forms of joints would also work: for example, dovetail joints, bridle joints, mortise-and-tenon joints, tongue and groove joints, dowel joints, to name a few.

Further, one of skill in the art will appreciate multiple apparatus10may be interconnected in any other suitable manner. For example, the apparatus10may be interconnected using connectors24manufactured of steel or any other conductive material and made in the form of plates, straps, hinges, braided wire, or any other suitable form of connector assemblies24.

FIG.10illustrates another embodiment of the apparatus illustrated inFIGS.1to9. In the embodiment ofFIG.10, the upper layer14includes an electrically conductive material or fabric60that may be operatively coupled to the support or base member12. In one embodiment, the fabric60may be glued or adhered to the underlying base member12using an adhesive. Alternatively or additionally, mechanical fasteners may be used to attach the fabric60to the underlying base member (as a substitute for or in addition to an adhesive). InFIG.10, dashed lines have been used to depict the underlying base member12, which has over the top of it, the fabric60that is conductive. InFIG.10, a side60aof fabric60is “pulled up” or “pulled back” from a corresponding side12aof the base member12to better illustrate the underlying base member12. The fabric may be replaceable or otherwise removable from the underlying base member12. As an example and without intending to be limiting, the fabric60may be canvas that is sprayed or coated with an electrically conductive composition, such as that described in the foregoing paragraphs, in order to render the fabric60electrically conductive or be made with conductive wires interwoven in to the material.

As shown inFIGS.7A,7B and8, in some embodiments the equipotential zone1′ includes a removable barricade system such as a fence34supported on and extending from the upper surface14aaround at least a part of the periphery of zone1′. Accordingly, as seen inFIGS.7A and7B, uppermost surface14ais provided with one or more locators32for releasably receiving therein a longitudinal or upstanding, substantially orthogonal member or post34aof the fence34, wherein post34ais substantially orthogonal to the uppermost surface14a. In one embodiment, the locator32may also be adapted to receive therein an angled, longitudinal member or post36aof a second fence36.

The barricading system is erected by locating the longitudinal members34aand36aof the fences34and36, respectively within the perimeter of interconnected plurality of apparatus10. The longitudinal members are located within a friction fit device such as locator32that connects and disconnects easily to and from the uppermost surface14. In one embodiment and as shown inFIGS.7A,7B and9, the locators32may be brackets with holes or sockets32a,32bthat provide a friction fit for the posts34a,36aof the fences34,36. This enables the posts34a,36ato extend from and be supported by the apparatus10, rather than having to support the posts34a,36afrom the ground of the surrounding work area3. This eliminates the time and issues associated with pounding steel fence posts directly into the ground. The locators32may be screwed directly into the apparatus10or bolted on using integrated threaded inserts in the upper layer14. Alternatively, the upper layer14, either alone or in combination with the base member12, may include molded or otherwise formed depressions in place of the metal brackets for barricade installation, as shown for example inFIG.4.

As stated above, the locator32, in one embodiment, may comprise two mounting slots or sockets32aand32bfor receiving the longitudinal members of the barricade system. In the embodiment illustrated inFIG.9, sockets32aand32bhave a square cross-section so as to define a square opening. However, this is not intended to be limiting. As one skilled in the art will appreciate, the sockets may be of other cross-sections including round and may have other shaped openings formed therein. Socket32aextends perpendicularly from a flange32cof the locator32. Posts34amay be mounted substantially orthogonally to the upper surface14aof apparatus10within these sockets32a. Optionally, the second socket32bmay extend from the flange32cat an angle α relative to socket32a, for example at approximately 45 degrees, such that posts36amounted in sockets32bextend outwardly at angle α to form an exterior barrier or fence36which is spaced apart from the interior barrier or fence34. One or more horizontal members34cand36c, such as ropes, boards or any other suitable member for forming a barrier, may be strung between the posts34aand36a, respectively, so as to form the fences34and36. Preferably, the socket32bmay be tilted at angle α and the length of the posts36amay be sized so as to create an exterior barrier36that is at substantially the same height as interior barrier34, located at a horizontal distance A from the outer perimeter of equal potential zone1′, as shown for example inFIG.8. Without intending to be limiting, the distance A may for example be in the range of six to twelve feet, or any other suitable distance so as to prevent or deter contact between persons on or equipment bonded to the equal potential zone1′ and any persons or equipment located outside the exterior barrier36, thereby preventing the electric shock that may otherwise occur due to a difference in potential between persons on or equipment bonded to the equal potential zone1′, and persons or equipment located off of the equal potential zone1′. The fence posts34amay be and36amust be non-conductive plastic poles which may be made from any rigid non-conductive material such as polyvinyl chloride (PVC), fiber reinforced plastic, or fiberglass.

In another aspect of the present disclosure, and with reference toFIGS.7A and7B, the equipotential zone1′ is further provided with an insulated bridge50, for the purpose of providing an insulated transition between the work area3and the equipotential zone1′, so as to avoid step potential that may occur when a person places one foot on the zone1′ while leaving the other foot on the ground of work area3. When that occurs, if the electrical potential of the work area—3is different from the electrical potential of the equipotential zone1′ the person may experience an electric shock. Therefore, the bridge50is electrically insulated from both the work area3and the equipotential zone1′ such that a person moving on and off of the equipotential zone1′ cannot do so while having one foot in the zone1′ and the other foot on the ground3. In one embodiment, the insulated bridge50may be connected at one end to one or more apparatus10using friction fit52or other quick connecting devices. In one embodiment, the insulated bridge50may include non-conductive handrails51, a non-slip surface53, gates55, and suitable insulators for electrically isolating the insulated bridge from an underlying surface such as ground. The bridge50and associated accessories may be made of fiber-reinforced plastic or any other similar material.

InFIGS.11to13D, wherein, again, like references depict like elements in each view, various embodiments of the insulated bridge50as contemplated by the Applicant are depicted. As before, the insulated bridge50insulates a person exiting or entering the equipotential zone1′.

In one embodiment and with reference toFIGS.11A and11B, the insulated bridge50A is a modular bridge having pre-fabricated bridge modules70. In one embodiment, an individual module70may span the entire length of the bridge50A. The modules may be shipped to a bridge site (for example, adjacent work area3) and may be assembled on site. Assembly may include fastening the modules together using fasteners or interconnecting them using complementary interconnecting means provided on the modules.

In one embodiment and with reference toFIG.11A, each bridge module70includes a deck section70asupported on a structural support section70b. The structural support section70bincludes one or more support legs72for properly supporting the deck section70aand the persons and payload that may pass over the deck section. In one embodiment, in order to stabilize the support legs72on the work area3, each support leg may have a foot member72aat its distal, lower or free end. The foot member72ais adapted to rest upon the work area3. The deck section70ahas a floor74which is a substantially flat and continuous surface. In one embodiment, the deck section may include a handrail76extending, preferably, along the entire length of the deck section70a.

In some implementations, it is contemplated that the deck section70aand the support section70bare two separate components, adapted to be connected to each other to attain a use configuration. In other implementations, the deck section and the support section may be constructed as a single piece.

In one embodiment and with reference toFIG.11B, one or more bridge modules, typically end bridge modules, may be associated with a stairway79. As with conventional stairways, stairway79includes foot treads79aand handrails79b.

All the elements of the insulated bridge depicted inFIGS.11A,11B, and12including support legs72, the deck section70aand its various components, the stairway and its various components are made of electrically insulating materials or elements. For example, without intending to be limiting, insulating materials may include fiberglass, fiberglass reinforced plastic (FRP), thermoplastic polymeric materials such as polyvinylchloride (PVC). The insulated bridge50and its various components may be made of an insulating material generally used to construct live-line tools such as so-called hot sticks.

For ease of shipping, length of each bridge module70may be approximately four feet. Also, length of each support leg72including a thickness of the foot member72amay be one foot. As one skilled in the art will appreciate, these dimensions may vary depending on a multitude of factors including size of the equipotential zone1′, its elevation from the work area3, voltage levels of the energized power lines located in the vicinity of the equipotential zone1′ and such.

FIGS.12to13Ddepict alternative embodiments of the insulated bridge50.

With reference toFIG.12, the insulated bridge50B depicted therein is fabricated from plastic by a blow molding process. In order to reduce weight and render the bridge cost-effective, the bridge may have a hollow interior. Further, the bridge may be of a single piece construction or may be of a modular construction having one or more cooperating bridge modules/blocks. Further, the bridge may be associated with one or more stairways79. Typically, the stairways79are associated with opposed ends of the bridge. In one implementation, the stairway(s)79may be integrally formed with a bridge module. In another implementation, the stairway(s)79may be a separate plastic, blow-molded unit that may be connected to one end of the bridge.

As with the embodiment depicted inFIGS.11A and11B, all components of the bridge50B illustrated inFIG.12are also made of electrically insulating materials or elements.

In the event the bridge50B ofFIG.12is of a modular construction, in order to bridge discontinuities formed between connecting edges of adjacent bridge modules, the floor74of the deck section may be constructed as a single piece that is adapted to overlie the entire length of the deck section so as to form a substantially continuous surface.

Applicant, in one embodiment, has contemplated constructing the stairway79depicted inFIG.12as follows: constructing a stairway from a rigid form rendering structure such as plywood, creating a mold/shell around the plywood using a non-conductive material, removing the plywood to create a hollow shell in the substantial form of the stairway. Examples of the non-conductive material that may be used in the process include fiberglass, plastic, rubber (in the form of a spray or sheets). Applicant believes these insulating materials are capable of being moulded/formed/draped/sheeted around an underlying form rendering structure such as plywood.

FIGS.13A to13Dillustrate another embodiment of the insulated bridge50. In this embodiment, insulated bridge50C includes blow-moulded bridge modules that may be interconnected to form bridge50C. Alternatively, the bridge50C may be constructed as a single piece by a blow molding process. Again, as with other embodiments, the bridge50C may be associated with a stairway79. In one implementation and with reference toFIG.13B, the stairway79may be constructed as follows: frames or blocks that function as foot treads79aare first constructed using electrically insulative materials. These frames or blocks are then interconnected using external connecting means or complementary interconnecting means provided on the frames or blocks to form a partial stairway79. Each frame/foot tread79ais further provided with mounting holes79con opposed ends thereof for receiving elongate members of the handrail79b. Typically, each stairway79may have between two to eight foot treads79a.

Further, with reference toFIG.13D, in order to increase the insulative properties of the bridge50C, the foot treads79aand the floor74of the deck section70amay additionally be covered by an electrically insulative material or fabric61such as rubber or other insulating materials. As described, fabric61can be removed during transport of the bridge and be laid on the said surfaces prior to use.