This invention relates to shielding structures against radiation by the use of radiation absorbing coal combustion residual components (“CCR”) and other carbon containing materials. More specifically, this invention relates to shielding against electromagnetic pulses (EMP), high-altitude electromagnetic pulses (HEMP), geomagnetic disturbances (GMD), and intentional electromagnetic interferences (IEMI). The application discloses structures utilizing CCR and other carbon containing materials as a radiation-absorbing material per se, and also techniques for enhancing the IEMI and EMP protection afforded such structures. Examples of structures utilizing CCR are disclosed in applicant's U.S. Pat. Nos. 9,790,703 and 9,988,317.
The world has grown dependent upon the use of electronics in nearly every facet of life. Safety, security, and normal day-to-day life heavily involve the use of electronics. Accidental and intentional conducted and radiated electromagnetic or geomagnetic emissions are capable of introducing damaging high electrical currents and voltages. These high currents and voltages are capable of causing disruption, data loss, and even permanent damage to the targeted electronics. An increased level of research and development is being carried out to protect critical structures, facilities, and components against these harmful emissions.
Prior art protection against radiation-induced damage has included geographic separation, redundancy, technical workarounds, or repair procedures as long as parts are available. This application discloses constructing an Intentional Electro-Magnetic Interference (IEMI) protective barrier using Coal Combustion Residuals (CCR) as a major component. These barriers can be constructed around EMP protective, or non-protected EMP structure(s) to provide the additional IEMI protection. IEMI protective walls can be used to protect many types of critical infrastructure systems as outlined by CISA but specifically control centers and electrical substations for utilities will be a sector that IEMI protective structures will provide much needed protection.
It has been verified by testing that CCR absorbs IEMI electromagnetic energy at a greater effective rate than common soils. This greater absorption characteristic of CCR allows for a superior IEMI protective barrier and at the same time allows for the beneficial use of CCR. The IEMI barriers can be built with spaced, framed panels, but the preferred embodiment is to construct an IEMI protective barrier berm using CCR. Using CCR in this beneficial use will allow not only for IEMI protection but also protection from other destructive forces that an adversary may use to damage critical infrastructure, as was perpetrated on Apr. 16, 2013 by the Metcalf sniper attack on Pacific Gas and Electric Company's Metcalf Transmission substation in Coyote, Calif.
The variables for IEMI protective construction apply regarding liners, liner placement, encapsulation, low leaching/low permeability, slope stability, mesh, and mesh placement.
Protection against radiated and conducted electromagnetic emissions such as HEMP/EMP, GMD, and/or IEMI can be accomplished by the electromagnetic shielding methods and devices described in this application. Shielding can be applied to CCR facilities and the components, systems, and subsystems which make up the facility and/or the CCR material itself. Shielding against radiated emissions is accomplished through creating a highly conductive surface around a protected area to reflect and/or absorb radiated energy so it does not cause damage. The highly conductive surface is able to redirect and/or absorb the radiated energy to prevent or minimize exposure to damaging electromagnetic energy. Conducted emissions are generally diverted or blocked through the use of filters with discrete components that pass desired energy and block undesirable or damaging energy before it enters a protected area. Shielding of radiated and conducted emissions can be accomplished through one or a combination of methods and devices described in this invention.
Additionally, EMP has three components which are commonly referred to as E1, E2, and E3. These components vary by frequency, intensity, and longevity. Shielding against each of these components may be accomplished by different methods and techniques. One or multiple layers of conductive mesh may be positioned around the entire CCR structure, within the CCR material itself, around specific components or subsystems, or in natural earth geotechnical formations below or otherwise proximate to the CCR structure. Generally, conductive mesh will provide shielding from EMP events in a lower frequency range; however the size of the free air space within the mesh, commonly known as the mesh size, will be selected based on the desired frequency ranges that are required to be protected against.
It is therefore an object of the present invention to provide shielding against harmful radiated and conducted electromagnetic and geomagnetic emissions to structures by incorporating CCR components into these structures.
It is another object of the present invention to provide EMP, HEMP, GMD, and/or IEMI shielding to structures having CCR components.
These and other objects and advantages of the present invention are achieved in the preferred embodiments set forth below by providing an electromagnetic emission shield for protecting a coal combustion residue facility having a carbon-based material or other electronically conductive material. The shield may be formed into an arch and positioned inside an interior space of the coal combustion residue facility and a plurality of conductive mesh layers embedded into the carbon-based material.
In another embodiment of the invention an electromagnetic emission shield for protecting a coal combustion residue facility has a layer of carbon-based material positioned underneath the coal combustion residue facility and a plurality of conductive mesh layers embedded into the carbon-based material.
According to another embodiment of the invention, an electromagnetic emission shield is provided for protecting a facility having a volume comprised of coal combustion residue, the shield comprising a carbon-based material positioned inside an interior space of the coal combustion proximate to and interposed between a potential source of electromagnetic emission and the facility.
According to another embodiment of the invention, at least one electro-conductive mesh is embedded into the carbon-based material.
According to another embodiment of the invention, the shield comprises an enclosure having a weight-bearing arched roof.
According to another embodiment of the invention, the shield includes an enclosure having a weight-bearing arched roof, vertical side walls surrounding the facility, and a slab floor.
According to another embodiment of the invention, the slab floor is undergirded with coke breeze in which is embedding at least one layer of electro-conductive mesh.
According to another embodiment of the invention, vertical side walls are welded to the roof.
According to another embodiment of the invention, an EMP-protective composite structure is provided and includes at least one enclosure having walls, a ceiling, at least one ingress/egress portal and a base, each of the walls, the ceiling, the ingress/egress portal and the base including at least one blast-resistant structural panel and at least one layer of an EMP barrier comprised of CCR that provides magnetic conduction, field absorption and field reflection fully-enclosing the structural panel. The blast-resistant structural panel includes a frame constructed of spaced-apart frame members of a ferrous material or other electrically conductive material, frame reinforcing members or rebar extending between the frame members, a cementitious layer in which the frame is embedded and an EMP or rebar shielding mesh embedded in the cementitious layer. An encapsulation barrier includes an overlying layer of an impermeable cementitious material having a blast-deflecting surface defining an acute blast-deflecting angle with respect to a major plane of the base overlying the at least one enclosure, and a HEMP protective door is formed in the enclosure to absorb and deflect EMP.
According to another embodiment of the invention, the encapsulation barrier comprises an overlying layer of an impermeable cementitious material and a layer of vegetation overlying the layer of impermeable cementitious material.
According to another embodiment of the invention, the blast-resistant structural panel includes an expansion joint extending along a major side thereof for joining the structural panel to a like structural panel that allows for movement of the structural panel relative to other joined structural panels due to expansion and contraction while maintaining intact EMP protective features.
According to another embodiment of the invention, the enclosure includes a plurality of structural panels joined to form enclosed spaces equipped to perform the functions selected from the group of enclosed spaces consisting of operations center, living quarters, communications, data center, mess hall, kitchen facilities, restroom, shower facility, laundry, storage for food, water, medical supplies and equipment, apparel and hygiene-related supplies and equipment, generators, battery storage, transformers, power substation, power plant SCADA system; fuel supply, storage for spare and replacement parts for operating equipment.
According to another embodiment of the invention, a circuitous path extends from an exterior of the EMP-protective structure, through the encapsulation barrier and to the at least one ingress/egress portal of the enclosure, the circuitous path configured to absorb and deflect EMP as the EMP passes along the circuitous path, wherein the circuitous path comprises a labyrinth having a plurality of right-angle turns, curves, spirals, or baffles though the EMP barrier that provides a two-stage shielding system,—a high frequency “absorptive” section, and a lower frequency “Waveguide” magnetic and electric field exclusion system. The circuitous path shields against magnetic field conduction and electric field radiation through absorption and field reflection with respect to electromagnetic radiation entering the path from the exterior of the EMP-protective structure.
According to another embodiment of the invention, a structural panel for use in constructing an EMP-protective composite structure is provided, the structural panel including spaced-apart frame members of a ferrous material, frame reinforcing members extending between and connecting the spaced-apart frame members; and a cementitious layer in which the frame is embedded.
According to another embodiment of the invention, an EMP absorbing mesh is embedded in the cementitious layer.
According to another embodiment of the invention, the blast-resistant structural panel includes an expansion joint extending along a major side thereof for joining the structural panel to a like structural panel that allows for movement of the structural panel relative to other joined structural panels due to expansion and contraction while maintaining intact EMP protective features.
According to another embodiment of the invention, an insulation layer is provided coextensive with a major surface of the panel.
According to another embodiment of the invention, the panel is adapted to be fabricated in a horizontal position and then tilted in situ into an upright position to form a part of the enclosure.
According to another embodiment of the invention, the cementitious layer is selected from the group consisting of lightweight concrete, epoxy concrete, ultra-high performance concrete and autoclave concrete.
According to another embodiment of the invention, an RF filter is provided that includes an electrically-conductive pipe defining a void filled with carbon-containing materials to provide high-frequency filtering, and enclosed on both ends by end caps including openings through which extend respective electrical stress-protected bushings, an electrically-conductive cable extending through the length of the filter, the filter adapted to be positioned to extend between an RF unshielded area through a shield to a shielded area of a facility to be protected from RF.
According to another embodiment of the invention, a plurality of RF filters are positioned in spaced-apart position relative to each other for providing RF shielding to the facility.
According to another embodiment of the invention an RF filter is provided that includes a plurality of electrically-conductive elements defining a void filled with carbon-containing materials to provide high-frequency filtering, and enclosed on both ends by through which extend respective electrical stress-protected bushings. An electrically-conductive cable extends through the length of each of the filter elements, and the filter elements are positioned in an array within an enclosure, the enclosure having a RF shield positioned within the enclosure defining on one side an RF shielded area and on another side an RF unshielded area, and through which the filter elements extend into and from an area of a facility to be protected from RF.
The present invention is best understood when the following detailed description of the invention is read with reference to the accompanying drawings, in which:
The embodiments shown in the drawing figures have certain features in common which are described below before providing specific details of the individual drawings. In general, enhanced radiation absorption in CCR structures is achieved by use of various panels and walls that include a radio frequency shielding mesh. The mesh may be welded, woven wire fabric, tied together with tie wire to form a continuous secure connection, formed with end loops having a threaded round or oval bar that runs perpendicular to the loops to tie the sections of mesh together, or formed with a hook and claw method. The mesh may be made of carbon steel, or any other material that can effectively conduct electricity and/or magnetic fields. The mesh may be coated and/or dipped to prevent corrosion. Corrosion may be due to the varying PH balances in the CCR material. Commercially available industrial coatings are envisioned as well as specifically developed coatings.
Conductive material, other than meshes, which produce the same or similar results, may be placed within the CCR structure, components, or CCR material itself. Shredded scrap metal, such as from vehicle shredders, steel fibers, textured glass, and other similar products can be utilized in and around structures having CCR components. Textured glass and shredded scrap metal may be used. These materials can be mixed directly into the CCR material itself, or formed into defined sections placed in and/or around the structure, for example arched, vertical, and/or horizontal formations. The material could also be placed in a section of soil located in the CCR structure or below the slab-on-grade portion of the interior structure which may be designed to be in a carbon-based material (a.k.a. carbon-containing material), other than CCR, CCR and soil, or any other acceptable material that will provide the desired shielding.
EMP absorption may be optionally enhanced by various additives and constructions which increase carbon content of the CCR structure. Some CCR structures already have high carbon content and may not require any enhancement. A carbon-based material, such as coal coke breeze or pet coke, may be in the form of an additive within the CCR material itself, or positioned as a defined construction proximate to or within the interior space of the CCR structure to enhance absorption within a defined frequency range. Carbon-based material may be used singularly or in combination with other carbon enhancing materials. It is also envisioned that carbon-based material may be attached to a liner or other barrier.
CCR material compositions typically vary in carbon content within a specific site or different sites. This variation may determine the size, type, and/or thickness of other elements of the CCR shielding required. These variables will be the main determining factors in the amount and extent of any carbon enhancing material required.
An arch is one specific technique for providing shielding of the type envisioned in this application. The percentage of carbon in the arch may be determined by the aforementioned site-specific variables, or a general predetermined amount, and the placement of the interior spaces in relationship to the bottom of the CCR. It is envisioned that the other shapes or configurations such as vertical sides and horizontal top/bottoms may be utilized in combination with arch structures. Construction of vertical wall/panel sections may be accomplished by using construction trench boxes. A floor shield may also be formed of mesh and/or a defined layer of a carbon-based material positioned underneath the floor of the interior structure. The entire mass of CCR material itself can be increased in carbon content in lieu of placement within the CCR structure depending on the type and amount of electromagnetic shielding required.
A combination of carbon enhancing material and mesh may be utilized to prevent electromagnetic or geomagnetic forces from penetrating upwards into the interior spaces of the CCR structure. While two layers of mesh and three layers of carbon enhancing material are shown, the amount, type, and thickness of the layers is dependent upon site specific requirements. The mesh may be fastened to sheet piling or spaced frame metal panels by welding, bolted bus bar type connection, and/or any other fasteners that are capable of producing a continuous metal to metal connection. Mesh from the exterior side of the interior space wall may be connected at an equal elevation or a lower elevation point to create a continuous 360 degree shielding around the interior spaces.
When the interior spaces of a CCR structure are constructed out of precast concrete or poured-in-place concrete, a metal plate may be inserted into the concrete to have a connection point for the mesh on both the interior and exterior sides of the interior space. Often it is necessary to test the properties of the installed shielding. A system for testing may be integrated into the CCR facilities for continuous or discrete testing. One testing system has multiple loop coils which may be energized so that the amount of energy emanating into the protected areas may be measured. These measurements enable the shielding effectiveness to be calculated so that the integrity of the shielding can be determined. Testing may also be accomplished by directly energizing conductive meshes around the facility using different frequencies and power levels so that shielding effectiveness may be calculated in protected areas to give confidence in the overall level of shielding that is present inside the CCR structure.
Radio frequency (RF) absorption can be tested using specially fabricated probes. These probes use copper tubes that have a pre-determined cross section diameter and length (for example, 1 inch in diameter and 10 feet in length) with caps and/or attachments that allow for the use of demountable components such as RF-type connectors, clips, or other means of connecting/disconnecting the probes.
The probes are energized with RF energy of any frequency. A typical frequency range is from 10 kHz to 1 GHz or higher for IEMI. RF energy is injected on one end of the probe, and the remaining energy is removed on the opposite end of the probe. The probes can be used to characterize the absorption properties of any material. The difference between injected energy and harvested energy is the absorption of energy along the probe. When the probe is placed or buried within various materials the inherent ability to absorb RF of the material surrounding the probe may be determined when a frequency of a predetermined bandwidth is swept across the spectrum. Additionally, when the probes are buried in CCR, the ability of CCR to absorb, for example, HEMP/EMP energy from 10 kHz to 1 GHz can be determined. This allows for the suitability of CCR for HEMP and IEMI shielded structures to be determined.
Air and/or personnel entryways into the CCR structure may be created through the use of an RF absorber in conjunction with a Waveguide Below Cutoff (WBC). The entryway will be comprised of an RF absorber, such as encapsulated CCR, coke breeze, MET coke, PET coke (containing varying percentages of carbon) or other carbon or non-carbon absorbing material with welded steel or welded steel mesh embedded in the RF absorber and configured to create a WBC. The entryway will function such that low frequency electromagnetic waves will be blocked by the WBC and higher frequency electromagnetic waves (above the cutoff frequency) will be absorbed by the RF absorber thereby creating a personnel or air entryway capable of blocking RF energy without utilizing an RF door. The entryway path may or may not curve or turn to help facilitate RF absorption. The entryway may include rudimentary RF shielding doors, turnstiles, or other RF absorbing features to improve overall RF shielding performance.
The removal of RF energy from wires, cables, conduits, pipes or other metallic fixtures may also be necessary. Wires, cables, conduits, pipes or other metallic fixtures may be embedded within materials such as encapsulated CCR, coke breeze, MET coke, PET coke (containing varying percentages of carbon) or other carbon or non-carbon absorbing material to significantly reduce high-frequency RF energy. This has applications for power lines, signal lines (such as those in power substations), control lines (such as those in power substations), and metallic pipes (such as water/sewer/gas lines) that may not be otherwise configured to exclude RF energy.
An electromagnetic filter may be created out of utility-grade discrete components. Air-core inductors, or other types of inductors that are of the type in use by electric utilities along with capacitors of the type that are used by electric utilities for power factor correction, or other purposes may be used to create a filter. This filter can be utilized independently or in conjunction with other filters to provide a range of frequencies or attenuation levels required by a particular application. One example is a HEMP filter (from 10 kHz to 1 GHz or more).
Medium-voltage power bus bars may be created to feed power into a CCR structure. The bus bar may be 10 ft or longer in length and of sufficient cross-section to transmit electrical power without excessive heating. The bus bar may not conduct significant amounts of RF energy. The bus bar may be insulated with nylon, PVC, Sulfur Hexaflouride Gas, or other insulating material or combination of insulating materials. The bus bar may be embedded in encapsulated CCR, coke breeze, MET coke, PET coke (containing varying percentages of carbon) or other carbon or non-carbon absorbing material which will act as an RF absorber and will prevent significant RF energy from being transmitted by the bus bar. The bus bar may be used in conjunction with the filter to operate across the entire HEMP pulse spectrum.
This arrangement might be used for applications like electric power substation houses where multiple conductors may need to pass from an unshielded area to a shielded area, and applications (such as high-speed protective relays) that may not be compatible with conventional filters, as is sometimes the case. Grounding shields from the cables would be removed for the portion of the conductors that pass through the carbon containing absorbing material. However, the carbon RF filter is utilized it will be configured so that one end is outside of the shielded environment, and the other end is inside the shielded environment
Inside of the RF shielded environment, other protective devices, such as metal-oxide varistors may be employed to reduce any remaining RF artifacts. With higher frequency RF artifacts removed, MOVs may be effectively employed. Often when high-frequency artifacts are present, an MOV does not act fast enough to protect against conducted RF energy that may be damaging. With the higher frequency artifacts removed, the “rise time” of any RF energy will be significantly less, allowing for conventional and/or less expensive MOVs that have a slower rise-time response to be used to provide more effective protection to a conductor in a shielded environment.
One of the technical principles employed with this invention is called the “Skin Effect.” The skin effect is the tendency of a high-frequency alternating current, such as radio frequency energy, to become distributed within an electrical conductor in a way that the current is mostly carried near the surface of a conductor (aka: “the skin” of the conductor). The depth of the “skin” is dependent upon frequency of the electrical current—so DC power would utilize the whole conductor, utility AC power would have very limited skin effect, because it is low in frequency, and RF energy from an EMP or IEMI or other RF source would flow mainly on the outside of a conductor. By flowing on the outside of the conductor, the RF energy is closer to the carbon-containing material that absorbs the RF energy. This allows the RF energy to be removed from the conductors as it propagates across the conductor. Another technical principle employed with this invention is “re-radiation” of RF energy that is travelling down a conductor. As RF energy frequency increases, the tendency for RF energy to reradiate from conducted energy to energy traveling in free-space (or within some other medium in which a conductor is placed) as it travels along the conductor. When the energy reradiates in carbon-containing material, it is absorbed and converted to heat by the carbon, which is the same principle that pyramidal carbon absorbers, commonly used in “anechoic chambers” or EMP testing chambers.
For applications with utility AC power or DC power from alternative energy (as examples, but not limited to these examples) the carbon-containing RF absorber will absorb any energy that is reradiated from a conductor inside of it. The effectiveness of the carbon-containing RF absorber will be dependent on the thickness of the RF absorber, with higher frequencies (that have a shorter wavelength) being absorbed by a shorter thickness of carbon material in which a given conductor may be embedded than for lower frequencies (with a longer wavelength).
The EMP Protective composite enclosure panel systems and materials in this application have unique features that allow for, if required, exceptional corrective and maintenance work which can be easily located and performed to allow for long-term Intentional Electro Magnetic Interference (IEMI) and EMP shielding, absorption and conductivity protection requirements of the system(s) for many decades, if not longer, to come.
IEMI weapons generally have a frequency spectrum from 80 MHz-10 GHz (or higher) and project either a narrow-band repetitive pulse, a wide-band repetitive pulse, or some other pulse modulation scheme designed to damage, disrupt, or upset electronic systems that are in their antenna focus area. The maximum field-strength beam of IEMI weapons is generally narrow (a few degrees wide in beam-width) and can often be aimed to focus on specific systems or areas of a building.
Referring now specifically to the drawings,
The meshes in the slabs 50 and 54 are welded and/or electronically connected to the vertical slab walls 44, 60, which are concrete and steel.
The details of the slab walls, for example wall 44, are shown in
Referring now to
The structure 80 includes a shielded air intake 92, a shielded personnel/material entryway 94, a power filter vault 96, and a power entryway 98. Two layers of mesh shielding 100 reside within the relatively shallow layer of carbon-containing or carbon supplemented material 86. A floor plate 102, which may be a composite panels, steel plate, a mesh, or a combination of the two or more, embedded in carbon containing material such as coke breeze and/or CCR provides primary protection against electromagnetic energy penetrating upwards from the ground or bottom portion into the interior spaces of the structure 80.
Referring to
As shown in
Further details of the manner in which various structures are provided with enhanced EMP protection are shown in
The sidewalls 244, 242 of the structure 220 include an exterior concrete structure 242 supported by a metal casement 244. A further secondary non-structural carbon heavy concrete layer 246 provides innermost protection. The base of the structure 220 is supported on crushed stone, for example, a six-inch bed 250 of ¾ inch stone. A mat foundation 252 enclosed within a vapor barrier 254 supports the sidewalls 240. The mat foundation 250 supports a slab 256 formed of, for example, a 6 inch concrete slab on grade. The coke breeze 252 includes embedded EMP absorbing mesh 258 extending throughout the length and width of the coke breeze or other carbon containing material.
Further details of the metal casement 244 are shown in
Referring now to
A carbon RF reduces conducted RF energy on a conductor, whether directly superimposed on the conductor, or whether superimposed onto a conductor through free-space or other material. This carbon may be CCR, graphite, coke breeze, PET coke, calcined coke, or other carbon-containing material that is capable of absorbing RF energy. The carbon containing material may be configured in mats or sheets, it may be in granular form in various particle sizes, or it may be in any other form, provided it has the RF absorbing characteristics. Embedding a conductor in carbon-containing materials can act as an absorber of RF energy that travels along the conductor. This effect is such that a conductor thus configured acts as a filter, allowing the passage of intended low-frequency signals, such as electrical power in alternating current, or direct current forms, or low frequency signals such as those used in some sensors and actuator controls.
One specific embodiment of this feature is in electrical power into an RF shielded structure (this can include a HEMP shielded structure, an IEMI shielded structure, or a combination of both or any other structure that is designed to limit the incursion of RF energy into a protected/shielded space. A structure that has other applications (such as an “All-Hazard Total Protective Structure”) may also be RF shielded. Such a filter constructed in this way can be effective at different voltages, even voltages commonly referred to in electrical utility terms as “Low-Voltage”, “Medium-Voltage” or “High-Voltage” intended to refer to voltages from 0 Volts to voltages measured in the hundreds of thousands of volts or higher.
For example, a power line that is run through a carbon RF filter of this type will pass 60 Hz AC or Direct Current but will significantly reduce RF energy that may be intentionally or unintentionally travelling along the same conductor. This differs significantly from a typical RF filter that may be comprised of inductors and capacitors as commercially available because these filters will generally have some loss associated with their use. The carbon RF filter is a significant improvement over conventional filter technologies in that losses are eliminated other than those that are typically experienced in the same conductor not embedded in carbon-containing material for the purposes of carrying electrical current.
The filter may or may not be constructed so that conductors pass into a metallic enclosure (with proper insulation and electrical stress protection on the conductor entry and exit) that holds carbon containing material. In the event of an electrical fault, any current will be safely contained within the enclosure and safely allow for the “fault” to be cleared by typically used electrical equipment, such as fuses or breakers or other protection means. This type of shielding is required for conductors above a certain voltage level.
Conductors embedded in carbon may include those typically available from electrical conductor vendors, or it may be a specially designed conductor that is specially insulated inside of a nylon or PVC (or other electrical insulating material) tube. The use of SF6 (sulfur hexafluoride) or dry air or other material or gas may be used to create an insulating barrier inside of a non-conductive enclosure or pipe that allows for a metallic busbar (such as copper) to be embedded in carbon-containing material. The conductors, when appropriate as dictated by the electrical code, may be embedded directly in carbon-containing material with no specific enclosure.
The carbon containing material may be in a mat or sheet form and may be wrapped around individual conductors to provide RF absorbing/filtering characteristics.
As shown in
Referring now to
Transient suppression devices can take on many forms from arc contacts, to filters, to solid state semiconductor devices. Discrete semiconductor transient suppression devices such as the Metal-oxide Varistor, or (“MOV”), are by far the most common as they are available in a variety of energy absorbing and voltage ratings making it possible to exercise tight control over unwanted and potentially destructive transients or over voltage spikes. With higher frequency RF artifacts removed, MOV's may be effectively employed. Often when high-frequency artifacts are present, an MOV does not act fast enough to protect against conducted RF energy that may be damaging. With the higher frequency artifacts removed, the “rise time” of any RF energy will be significantly less, allowing for conventional and/or less expensive MOV's that have a slower rise-time response to be used to provide more effective protection to a conductor in a shielded environment.
Referring now to
For example, a berm 340 is shown in cross-section and has an isosceles or three sides equal trapezoid shape, with a relatively wide base 342, opposed inner and outer sloped walls 344, 346 surmounted by a relatively narrow top 348. The top 348 may be configured as a roadbed along which security or service vehicles may travel. The volume of the berm 340 is comprised of compacted CCR and other EMP absorbing materials, as described above. The berm may include a security fence. The base 342 of the berm 340 may be protected using the enclosure techniques described above.
Referring to
An electromagnetic emission shield for protecting a coal combustion residue facility according to the invention have been described with reference to specific embodiments and examples. Various details of the invention may be changed without departing from the scope of the invention. Furthermore, the foregoing description of the preferred embodiments of the invention and best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation, the invention being defined by the claims.
This utility patent application claims priority from U.S. Provisional Application No. 62/863,394, filed Jun. 19, 2019 and U.S. patent application Ser. No. 16/711,581, filed Dec. 12, 2019, which claims priority from U.S. Provisional Application No. 62/883,696, filed Aug. 7, 2019, the contents of which are incorporated by reference in this application.
Number | Date | Country | |
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62863394 | Jun 2019 | US | |
62883696 | Aug 2019 | US |
Number | Date | Country | |
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Parent | 16711581 | Dec 2019 | US |
Child | 16905406 | US |