Method, System, and Apparatus to Prevent Electrical or Thermal Based Hazards in Conduits
A method, apparatus, and system for protection from hazards of conductivity is disclosed using non-electrical means to disrupt electrical current with a thermovolumetric substance. The purpose of this invention is to prevent hazardous conditions from occurring by disrupting the flow of electrical current prior to the development of arc fault conditions.
Systems which are in connectivity typically include an infrastructure comprised of mechanical framework and means for disconnecting, regulating, controlling, distributing, and modifying the conducted material. Electrical arc-faults in connectivity occur when the operating current exceeds normal bounds; such as caused by differences in expansion of the conduit and metal contacts, a manufacturing defect, or Ohmic heating caused by increased resistance of the conductor due to galvanic corrosion.
Electrical arc faults in electrical connectivity generate white hot plasma and intense heat. Arc faults can be caused, for example, by a manufacturing defect, overload, or thermal expansion and contraction at the joints by the thermodynamics of current on the conductor. There is a plethora of publically available documents such as, “American Electricians Handbook” by T. Croft, F. Hartwell, and W. Summers (which is included in its entirety by reference herein), that teach electrical system designs and installations, as well as hazards related thereto. Other documents are publicly available that teach how to design systems that mitigate the related hazards with controllers, circuit breakers, ground fault detectors, and circuit interrupters.
For brevity, the following summary is focused on, but not limited to, systems comprised of conduits that conduct AC or DC electricity. The conduits are conventionally connected to metal lugs in a “junction box” or panel with connectors that provide connectivity, usually in a series fashion. The connectivity provides a path to a combiner box that aggregates. Several combiner boxes are often connected in a tree-like fashion for aggregating power into a transmission line. In practice, one or more combiner boxes include over-current protection and isolation means, such as relays, breakers, or insulated levers to deal with overloads and isolate safety hazards.
Briefly stated, the present invention is a device to provide autonomous disruption of connectivity without need for measuring temperature with thermometric sensors.
In the case of an arc occurring within connectivity, the intense heat generated can result in a localized fire of combustible material used in the connector's construction which quickly spreads to proximal combustible materials.
Ohmic heating, due to corrosion or loose connections, can also lead to an arc fault in junction boxes, combiner boxes, inverter boxes, and insulation within the electrical distribution system. The ohmic heating may also degrade the conductive material in a manner that when sufficient energy is present, an arc fault can be established in the conductive material itself.
Human trauma and electrocution can result by touching the metal frame and/or an associated electrically conductive structure of a system component, which is electrified by an arc fault. When the supporting energy of the arc fault is DC, there are no zero-crossings as in alternating current and the arc does not self-extinguish, but continues as long as sufficient energy exists.
There is a pressing need for an improved means described in detail in the present invention that acts autonomously to take action to prevent arc-faults from happening. It would therefore be desirable to provide an apparatus with means for pre-arc, unsafe-condition detection and mitigation therein that works even when voltages and currents are within normal limits. Further, the protection system would meet the 2014 National Electric Code (NEC) Handbook Section 690.11 and other NEC requirements (reference #1 in the list of non-patent documents, which is incorporated in its entirety by reference) by annunciating unsafe conditions in PV system equipment and associated wiring. The protection system would provide mitigation before the arc-fault occurs, shutting down the PV component with an unsafe condition; therefore preventing fire damage and human disasters by properly isolating only the unsafe component in a safe manner and alerting the system owner or consumer for replacement or reinstatement.
DISCUSSION OF PRIOR ARTIn preparing this application, a search of World Intellectual Property Organization (WIPO) member websites found over two hundred issued patents for detecting and protecting after electrical arc faults happen in chafing, overload, and wire short situations. None of these patents deal with methods or a system with means to pre-empt an arc fault hours, days, or even months before the discharge occurs. However, several patents and limitations thereof which are overcome by the present application are presented below.
There are numerous examples of prior art, including patents and publications that present principles, methods, systems, apparatus, and techniques for detecting and mitigating active arc-faults when they occur. There are numerous examples of art that teach detecting the arcing of a “load-side short,” as experienced when electrical equipment fails, causing fuses to break due to current increase of electricity supplied by a generator or power facility. These methods cannot work well when sunlight is the energy source, as is the case with PV modules. This means a solar-source arc continues, due to the sun's rays (either direct or reflected from the moon), unless the module is covered somehow to occlude the sunlight; or the connectivity upstream is disrupted.
While there are numerous patents for detecting current overload, which causes fire in panels and electrical outlets, our search of the World Wide Web and the USPTO site patent database did not find issued U.S. patents or U.S. patent applications that teach direct mitigation of unsafe conditions without need for an electrical device such as a temperature sensor. Nor were there examples of prior art providing mitigation when current and voltage are within acceptable limits.
U.S. Pat. No. 8,410,950, issued to Takehara, et al. (referenced in the list of patent documents and which is incorporated in its entirety by reference herein), teaches an electronic monitoring module for measuring voltage and current of PV panel output, comparing measured values against minimum and maximum values saved in the monitoring module, and outputting an alarm signal when a measured value is outside a range defined by the minimum and maximum values. The invention this patent claims contains various electronic monitoring and electrical inverter components which differ it from the present patent.
H. Bruce Land III, Christopher L. Eddins, and John M. Klimek (Land, et al.), in a paper publicly available on the web entitled, “Evolution of Arc-Fault Protection Technology at APL,” claims that an electrical fire is reported in the United States every five minutes. This paper (reference #9 in the list of non-patent documents and which is incorporated in its entirety by reference herein) documents that Applied Physics Laboratory (APL) created an automatic fire detection (AFD) system to detect and quench these fires. This paper also documents that APL developed electronically operated circuit breakers that are the follow-on to arc-fault circuit interrupter (AFCI) and ground fault interrupter (GFI) breakers.
U.S. Pat. No. 9,464,946 to Blemel et al. (referenced in the list of patent documents and which is incorporated in its entirety by reference herein) teaches using thermokinetic energy to forcibly open an electrical connector. The disruption mechanism in this patent stems from thermokinetic energy produced by heating of energetic materials as opposed to thermovolumetric, thermohydraulic, or thermoexpansive mechanisms listed in the present patent.
U.S. Pat. Publication No. 2016/0097685 to Blemel et al. (referenced in the list of patent documents and which is incorporated in its entirety by reference herein) teaches detection of state change in a thermomorphic material to detect an unsafe condition in connectivity. The disruption of the connectivity in the patent differs from the present patent in that no mention of thermohydraulic or thermovolumetric expansion mechanisms are made.
J. F. Sherwood in U.S. Pat. No. 2,815,642 (referenced in the list of patent documents and which is incorporated in its entirety by reference herein) teaches the use of the thermoexpansive properties of wax to produce hydraulic actuating pressure and eventually actuate a separate component. However, this invention requires a spring to compress the wax once cooled.
F. P. Mihm's U.S. Pat. No. 3,302,391 (referenced in the list of patent documents and which is incorporated in its entirety by reference herein) teaches a thermoresponsive material that expands when heated and pushes against a piston actuating a hydraulic force. The design in the listed patent utilizes a spring which enables the invention to return to a start position, whereas the present patent can only undergo actuation in a single direction.
Loveday et al. in U.S. Pat. Publication 2010/0095669 (referenced in the list of patent documents and which is incorporated in its entirety by reference herein) teach the thermoexpansion of wax to produce hydraulic force to an output shaft, thus providing means of displacement to a working object. The patent differs from the present patent in that a wax generator coupled to a hydraulic transmission devices is required for operation. The present patent utilizes direct thermohydraulic or thermovolumetric force from a thermoexpansive substance optionally augmented by force from a thermokinetic substance as opposed to a transmitted force.
Sheppard et al. in U.S. Pat No. 9,441,744 (referenced in the list of patent documents and which is incorporated in its entirety by reference herein) teaches a valve apparatus actuated by a thermoexpansive material. However, this invention differs from the present patent as the design requires a spring to compress the wax once cooled.
Lamb et al. in U.S. Pat No. 6,988,364 B1 (referenced in the list of patent documents and which is incorporated in its entirety by reference herein) teaches the thermoexpansion of wax to push against a diaphragm and produce an actuation force. This differs from the present design as it utilizes a diaphragm.
Pat. No. GB663907 to Sherlock (referenced in the list of patent documents and which is incorporated in its entirety by reference herein) teaches motion of a thermally responsive element utilizing the volumetric expansion of wax and a rubber sealing recess. The patent claims a thermally responsive element comprising a rigid housing and a resilient member which transmits motion to a rod. The expansion of a wax within the rigid housing causes a displacement of the resilient member and thus the displacement of the rod. The apparatus in this patent differs from the designs in the present patent as the device is a reversible actuator with no mention of application to disruption nor connectivity systems.
U.S. Pat. No. GB748131 to Standard-Thomson Corp (referenced in the list of patent documents and which is incorporated in its entirety by reference herein) teaches improvements in or relating to resilient telescoping diaphragms which contain a liquid or wax which expands or contracts based on temperature changes. The claims of the patent state that the apparatus can be used for reciprocating motion and contains reciprocating elements. Further, the apparatus in question is primarily for use in thermostatic valves, which have discrete open and closed positions and can switch back and forth to those positions at specified temperatures.
U.S. Pat. No. 3,166,892 to Sherwood (referenced in the list of patent documents and which is incorporated in its entirety by reference herein) teaches the design and sealing of an actuator utilizing thermally expansible materials as a mode of motion. The design consists of a pressure chamber filled with a thermally expansible material which is heated by an electrical heating element enclosed within the chamber. The patent claims an actuator comprising a housing, pressure chamber, power producing material in the pressure chamber, and a piston shaft for reciprocable movement which utilizes an improvement of sealing and shaft-lubricating. A reciprocable design enables the control of the actuator in both the forward and reverse directions.
U.S. Pat. No. 7,922,694 to Harttiq (referenced in the list of patent documents and which is incorporated in its entirety by reference herein) teaches the design of a drive device for a piston in a container containing a liquid product. The patent claims a drive device for a piston in a container containing a liquid product, where the liquid product causes the extension of a piston in a longitudinal direction only. An actively varying shape is further claimed, enabling the piston device to operate with different cross sectional shapes. The listed patent only describes an actuator which can move in forward and reverse directions, with no mention of utilization of actuation motion nor application to disruption of connectivity. The above patent utilizes a thermally expanding substance such as, but not limited to paraffin, in order to cause actuation. Two actuators are included in the design where the first and second actuators are used to cause a change in the shape of different segments.
The above inventions are meant for reversible actuation or forward and reverse motion.
U.S. Pat. Application No. 2005/0088272 to Yoshikawa et al. (referenced in the list of patent documents and which is incorporated in its entirety by reference herein) teaches the design of a thermal fuse incorporating a thermal pellet, which allows for a spring actuator to break an electrical connection at a specific temperature. The patent further teaches a method of producing said thermal pellet along with analysis and comparison of many polymeric materials which can serve as the thermal pellet material. Differentiation between this patent and the present patent is clear in that the present patent does not utilize springs nor a thermal pellet.
None of the above patents, patent applications, and publicly available prior art teach utilizing thermohydraulic substances to disrupt flow of electricity to mitigate an unsafe condition before sustained electrical arcing occurs.
ADVANTAGES OVER PRIOR ARTThe following summarizes advantages of the present invention over prior art. 1) The present invention provides means to utilize the ohmic heating phenomena which is symptomatic of progression leading to an electrical arc fault at a higher temperature; 2) can be added during manufacturing of the connector; 3) can be plugged-in during installation of connectivity; 4) can be added after the connectivity is installed to provide protection to existing systems; 5) has no electronic circuit which could fail; 6) has no electrical or mechanical contacts that make and break the connection; 7) can be embodied to cause disruption and eliminate further risk; 8) is easy to install or integrate into the connectivity. 9) is immune to producing false alarms due to naturally occurring RF emissions; 10) operates before there is a significant precursor change in voltage or current produced by an arc event; 11) is able to operate when repeated hot/cold cycles result in very low ampere electrical discharges across a sub-millimeter sized gap at joints within the connectivity component such as due to a factory defect in the connectivity component; or an installer does not make a proper connection causing a gap in the joint small enough to cause a self-extinguishing discharge which will subsequently result in an arc fault with associated high-temperature plasma energy.
The present invention differentiates from electrical arc fault protection devices that operate by detecting noise, radio frequency, light of plasma, or electromagnetic emissions of a discharge. The present invention also differentiates from electrical arc fault protection devices that operate by thermomorphic principles and thermokinetic principles to detect heat of an active arc or a fire. Additionally, such existing means are not-proactive.
The present invention differentiates from prior art in that it detects an electrical arc-fault by utilizing the thermovolumetric force generated by the heat associated with the hazardous condition to subsequently disrupt the flow.
The present invention omits the need for electronic modules and sensors used to recognize the artifacts of a live electrical arc fault, such as a flash of plasma, radio frequency emissions, current rise, or simultaneous voltage drop.
An advantage exists over thermal pellet-based thermal fuse designs in that thermal pellet based designs require a high degree of structural integrity from the thermal pellet as the thermal pellet acts as a structural barrier during normal operation of a thermal fuse. Furthermore, thermal fuses are produced for relatively low operating current and voltage. No indication is visible when a thermal fuse has activated, making troubleshooting more cumbersome.
The present invention has an advantage over designs which contain springs. Springs apply a constant force to the walls and components within the body of a design. Spring-based devices require higher structural integrity and the spring can also act as a pathway for electricity to flow in the event of a severe arc fault. Elevated temperature conditions can further affect the lifetime of spring containing devices as the structural integrity of a spring containing body is significantly reduced at regional hot weather temperatures.
For a disruptor, many advantages exist over the prior art in that many of the previously listed devices are classified as actuators. Actuators can have an open and closed position, or can be used for precise positioning. In this sense, actuators are considered to be reversible because they can be used to return to their original positions. Reciprocable or reciprocating actuators are designed to open and close frequently and reliably. Applications which use reciprocable actuators have the need to switch directions of motion. A thermoxpansive disruptor only ever needs to cause motion a singular time in one direction. For use as a safety device in arc-fault hazards, a non-reversible disruptor prevents reconnection of a connectivity while ensuring tampering with the device will not result in a hazard.
Thermal fuses, which are designed to cause a break in an electrical circuit, employ the use of metallic springs coupled to thermally-sensitive materials. The nature of a thermal fuse requires that an included spring be under constant tension or compression. Activation of a thermal fuse occurs when the thermally-sensitive material degrades and is allowed to structurally deform. The structural changes in the thermally-sensitive material allow for the motion of the metallic spring into a lower-energy position. Thermal fuses are irreversible single-use devices where the metallic spring is unable to be reset to a zero position. Conventional thermal fuses are designed for low-power applications where there is little risk of an arc-fault occurring. Because of the number of metallic components in a thermal fuse, arcing is more likely to occur, using the metallic springs as conducting pathways. Being fully enclosed and sealed devices, thermal fuses have no indication that a break in an electrical circuit has occurred.
BRIEF SUMMARY OF THE INVENTIONThe present application teaches a protection apparatus that utilizes a thermovolumetric expansion force as a means for improving the safety of electrical, chemical, and other distribution systems from the damage and hazard that is unrecognized by ordinary means, and which will eventually result in an electrical arc with resulting fire, electrical shock, or hazard to life. The focus herein is on applying the protection apparatus to associated connectivity wherein thermovolumetric force mitigates the risk of a future arc fault, enabling mitigation of the condition before the unsafe event occurs.
The present application describes use of a thermovolumetric expansion force due to temperature change, while enables isolation of unsafe conditions in virtually any system connectivity component.
As an example, the degree of heat generated by flow of electricity in a system is represented by the relationship Ohmic Energy=Current*Resistance (E=I*R). The relationship means that either increased resistance or increased current would eventually result in a DC arc with the hazards.
While the present specification uses the example of photovoltaic balance of system connectors to teach the principles, a person familiar with electrical systems would realize that connectivity devices are components found in pipelines that conduct gasses, petroleum, and sundry chemicals as well as conduits and electrical systems.
Various embodiments of the invention are disclosed in the following detailed description and accompanying drawings. Each drawing teaches how to implement the techniques and/or components to affect the purposes of this patent.
(1) End cap
(2) Reservoir piece
(3) Inner O-ring
(4) Outer O-ring
(5) Thermovolumetric substance
(6) Hollow cavity
(7) Outer sleeve
(8) Inner column
(9) End barrier
(10) Sliding ring barrier
(11) Stopper
(12) Retaining ring
(13) Threaded collar
(14) Threaded connection piece
(15) Central cavity housing
(16) Piston connection piece
(17) O-ring
(18) Ring barrier housing
(19) Retaining ring clips
(20) Guide fins
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Still referring to 3B, the magnified region has a retaining ring (12) which is designed such that the sloped walls of the stopper (11) possess a wider diameter than the uppermost portion of the retaining ring (12). Thus, in order for the stopper (11) to pass through the retaining ring (12), the retaining ring clips (19) are forced to deflect away from their original positions. Following the passage of the stopper (11) through the retaining ring (12), the retaining ring clips (19) return to their original positions thereby regaining their initial diameter. The design of the stopper (11) is such that it is unable to pass back through the retaining ring clips (19) after passing through them. This is accomplished by the design of the stopper (11) being such that it is narrower on its upper end and wider at its lower end with a gradual slope change between the two different diameters. Because of this, the narrow end of the stopper (11) is small enough that it can pass through the retaining clips (19) at the top of the retaining ring (12). The retaining clips (19) are gradually deflected as they slide along the sloped outer surface of the stopper (11). Because the retaining ring clips (19) flex back into the position they possessed before the stopper (11) was forced through the retaining ring (12) after passage of the stopper (11), the stopper (11) is unable to return through the retaining ring (12) while in the same orientation it was in when it passed through the retaining ring (12). This is because the diameter of the lower portion of the stopper (11) is wider than the post actuation diameter of the retaining ring clips (19). Thus, the retaining ring clips (19) are not gradually forced apart by the stopper (11) and instead of causing deflection of the retaining ring clips (19) the stopper (11) impacts with the retaining ring clips (19) preventing its passage through the retaining ring (12).
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The following is a detailed description describing exemplary embodiments to illustrate the principles of the invention. The embodiments are provided to illustrate aspects of the invention, but the invention is not limited to any embodiment. The scope of the invention encompasses numerous alternatives, modifications, and equivalents; it is limited only by the claims.
Numerous specific details set forth in the figures and descriptions are shown in order to provide a thorough understanding of the invention and how to practice the invention. However, the invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the invention is not unnecessarily obscured. For example, a disruptor could be manufactured integral to either a male electrical connector or a female electrical connector or both. For example, means to generate the disruptive force may be a mechanical device, or a kinetic substance, or a corrosive substance. Also, the thermovolumetric substance that produces hydraulic force sufficient to cause autonomous disruption of connectivity may be a compound comprising one or more ingredients including a substance such as, but not limited to, an essential oil or other means to enhance production of hydraulic energy. A dye or fluorescent substance that disperses during opening of the connector could be mixed with the thermovolumetric substance to provide a visible marker of where a disruption has occurred.
References are cited that provide detailed information about electrical systems, unsafe conditions of electrical systems, and approved techniques for implementing protection systems. However, a person with ordinary experience in instrumenting systems would understand the application also applies to technology such as but not limited to steam and chemical piping systems.
The embodiments of the invention set forth herein relate to detection, mitigation, and isolation of unsafe connectivity that incorporates the present invention for purposes of properly disconnecting the flow of electricity within in the connectivity.
In a best embodiment for use with electrical conduits, a connectivity disruptor assembly comprises an insulating body with a proximal end and a distal end and separable electrically conductive guides in a channel through the center of the body. Electrical conductors fit into the electrically conductive guides via the proximal end and distal ends of the insulating body. One or more hollow cavities within the body are filled with a dielectric thermovolumetric substance chosen for the properties of significant expansion above a selected temperature, with the purpose to produce sufficient hydraulic pressure within the chambers of the body to overcome the force of friction, static mechanisms, or adhesive bonding, securing the conductors within the electrically conductive guides, resulting in physical separation of the connectivity thereby disrupting flow of electrical current. In an alternate embodiment, the force causes movement of the electrically conductive guide, which frees the connectivity.
In another embodiment for a conduit for safely transporting a particular substance, a connectivity disruptor assembly comprises a body with a proximal end and a distal end and separable conductive guides made of a suitable non-reactive substance in a channel through the center of the body. Entrance and exit conductors fit into the conductive guides via the proximal end and distal ends of the body. One or more chambers within the body are filled with an insulating thermovolumetric substance chosen for the properties of significant expansion above a selected temperature, with the purpose to produce sufficient hydraulic pressure within the chambers of the body to overcome the force of friction, static mechanisms, or adhesive bonding, securing the conductors within the conductive guides, resulting in physical separation of the connectivity thereby disrupting flow of the particular substance within the conduit. In an alternate embodiment, the force causes movement of the conductive guide, which frees the connectivity or mitigates by rerouting the particular substance.
A technical contribution for the disclosed protection system is that it provides for unique autonomous mitigation of unsafe conditions at junctions of connectivity, such as an electrical system, and properly disconnecting the unsafe connectivity with hydraulic force before the unsafe condition that, if left unattended, could result in an unsafe event such as an arc or ground fault (in the case where conduits contain both anode and cathode), and the consequential damages thereto.
Another technical contribution for the disclosed protection system is that it provides means for containing an insulating thermovolumetric substance for quenching a plasma that results when conductors carrying elevated current at a juncture are insufficiently separated with respect to speed of separation or distance of separation. Without limitation, the quench can be accomplished by filling the void formed when the conductor separates.
One exemplary embodiment of the present invention is an apparatus that comprises at least one disruptor that releases sufficient hydraulic energy to force separation and unresettably open the circuit when a temperature internal to the connectivity rises to a desired trigger point to force open the circuit served by the connectivity to open and remain open when an excessive temperature condition is detected.
In a broad embodiment, the present invention extends to use in other equipment, which is subject to risk of damage, fire, and loss of property due to external heat such as from a fire or hot liquid, and from manufacturing defects.
In a best embodiment, a means for mitigating hazardous events is included within the connectivity. This includes but is not limited to a fire suppressant, plasma suppressant, electrical insulator, or expanding foam.
In another embodiment, a means for generating a signal indicative of disruption of connectivity in response to a hazardous event includes, but is not limited to: an acoustic device such as a buzzer; a visual indicator such as, without limitation, a lamp, a fluorescent chemical, a semaphore; or a device that produces electrical data.
In a differing embodiment, the apparatus is constructed with an insulating thermohydraulic substance selected for properties that will optimize mitigation of unsafe conditions, such as, but not limited to, an electrical arc. The substance releases sufficient hydraulic energy above a certain temperature to forcibly open the connectivity. Further, the nature of the plurality of constituents used in the embodiment is selected so that any byproducts produced are non-toxic and further, are insulating to provide arc quench.
In another embodiment, pre-detection of an emerging unsafe condition in the sensor device would send an unsafe condition signal, which results in an alarm and the associated connectivity system component being de-energized by disconnection of the flow of current with a disruptor constructed according to the teaching herein.
Another embodiment includes manual connection and disconnection of the connectivity from the system is possible without posing any risks or hazards. During installation or modification of a system which utilizes the connectivity, the connectivity may require manual disassembly. Disruption of the connectivity will be irreversible, requiring the connectivity to be removed and replaced from its installed location. Disassembly and replacement of the disrupted connectivity is safe and straightforward.
In another embodiment, the thermovolumetric substance is augmented with a sensor built into or inserted into the body. The forcible opening of the connectivity will remain the same, but a connector, which can detect when the connectivity is open, is implemented. A number of methods can be used in sensing the opening of the connectivity, including but not limited to: electronic sensors, physical sensors, optical sensors, and thermal sensors.
In a more detailed design of the alternative connectivity design in which the conductive guide is offset from the thermovolumetric substance, the threaded connection piece could be designed to include a locking mechanism or component or could, in some way, be permanently affixed to the central cavity housing such that it could not be removed after it was affixed to the central cavity housing. Additionally, the piston connection piece could include a method or mechanism to cause it to be securely affixed to the central cavity housing after initial installation until the thermovolumetric substance was thermally activated causing a subsequent actuation of the piston connection piece and thus disconnection of the connectivity.
The apparatus should be constructed to provide an amount of hydraulic force to permanently open the connectivity with the force provided by the thermovolumetric substance. A non-reversible pressure vessel is constructed of materials which can withstand and direct the energy of the thermovolumetric substance to the opening of the connectivity. A fundamental requirement of a hydraulic system is that the pressure required to achieve motion in the hydraulic system must be lower than the pressure which causes deformation or damage to the encapsulating hydraulic reservoir. Fulfilling the structural requirements of the connectivity system may utilize polymer materials or a combination of solid materials to ensure structural integrity and reliability of the connectivity under differing conditions.
The material used for producing the hydraulic energy should be encapsulated, such as, but not limited to, a suitable polymer of strength that provides accumulation of force needed to cause assured disruption of the connectivity.
According to one aspect of the present invention, the material used to produce hydraulic force along with the encapsulation material should be reliable and stable for the expected service life of the connectivity.
In accordance with a second aspect of the present invention, the apparatus could include features such as, but not limited to, a self-test function, an ability to annunciate, an ability to be interrogated by wired or wireless means, or an ability to interrupt current flow by opening the connectivity.
To test the functionality of the system, a person should create an apparatus for performing a series of measurement tests that produce data to determine the amount of hydraulic separating force generated by the thermovolumetric substance. To generate internal heating within a connectivity, ohmic heating can be utilized to simulate high temperature conditions that may occur within a connectivity in the case of a hazardous thermal event. An electrically conductive channel with a known high resistance should be used. After connecting to a source of electricity, incrementally increase current with a calibrated current source, such as a variable transformer. A thermocouple should be positioned to measure the internal temperature of the thermovolumetric substance. A pressure sensor should be attached to measure the hydraulic pressure.
Functionality of the system will further be tested using extreme yet safe conditions which will allow for the behavior of the system to be better understood during extreme conditions. As a safety device, the connectivity system must perform safely at conditions which are more hazardous than the connectivity is rated for. In the case of an electrical connectivity, heat of an exothermic chemical reaction or ohmic heating may be used to cause the initial separation of the connectivity, but arcing inside of the connectivity has the possibility to create ionized gases, which can serve as a conducting guide more easily. Efforts will be made to ensure that any arcing which occurs during the initial separation of the connectivity will not result in a hazardous situation.
In reduction to practice, we produced and experimented with several forms of prototype connectivity bodies with an internal chamber according to the teachings herein. A prototype of a thermovolumetric disruptor was constructed with 3-D printed and machined parts. Paraffin at room temperature was forced into the chamber. In practice, an injection mold to produce millions of pieces would be more efficient. The internal chamber was filled with paraffin, then capped with an air-tight lid. Paraffin was selected for the property of releasing hydraulic energy above 130 degrees Celsius. When the prototype disruptor was heated to 130 degrees Celsius in a temperature-controlled oven, the heat caused the paraffin contained within the sealed connectivity cavity to expand quickly, accumulating sufficient thermohydraulic force to separate the disruptor body.
To produce exemplary ohmic heating caused by corrosion at current typical of that of commercial connectivity at the current time, examples of corroded electrically conductive guides and pins were produced and used. The examples were assembled from simulated corroded terminals in the form of nichrome ohmic heating wires. The examples worked as described herein establishing that resistive heating within a connector well below 200 degrees Celsius that produces an arc can be means to disrupt unsafe connectivity preventing the arc from happening. Aside from internal heating, external heating tests of the connectivity were conducted in order to ensure that an external source of heat would still result in disruption of the connectivity.
Several different tests were conducted in order to evaluate the performance of different thermoexpansive materials. Initial testing of disruptor mechanisms were conducted utilizing actuators with a thermoexpansive substance inside. The simplest formation of a thermally activated disruptor was fabricated by enclosing paraffin wax inside of a metal piston onto which a force of 40 pounds was applied. Upon heating of the piston to a temperature greater than the melting point of the paraffin wax, the piston was able to move and displace the 40 pound weight a distance of 3 millimeters. Successful displacement of a large amount of mass by a relatively small piston apparatus indicated that paraffin or other thermoexpansive materials will perform adequately in the design of the thermohydraulic disruptor. A calculation using the diameter of the piston to be 3 mm shows that the pressure of the thermohydraulic substance is 59 megapascals (MPa) or 8.5 thousand pounds per square inch (ksi). This is a tremendous value of pressure and is more than suitable to cause disruption of a connectivity component by a variety of means.
Assessment of various thermoexpansive substances was performed using a procedure developed to characterize the expansion of several waxes at increasing temperatures. Commercial waxes from both Micropowders and Deurex were cast into pellets with care so as to prevent internal voids from forming. Measurements of both mass and volume were conducted on each pellet. Each cast pellet was placed in a test tube with a thermocouple, and the test tube was heated over a Bunsen burner. The temperature of the wax pellet was measured every 10 seconds during heating and during cooling. During heating and cooling of the wax pellet, a solid-liquid phase transition occurred, which was able to be seen as a plateau of the temperature curves. During a phase transition, there is latent heat required to convert a material from solid to liquid, thus the temperature of the transitioning substance is maintained at the transition temperature for a short period of time. Volumetric expansion was conducted in a similar manner. A wax pellet was placed into brake fluid inside of a test tube. Brake fluid was chosen as a liquid that could withstand high temperatures without burning or causing unexpected interactions with the wax. In order to gain an accurate measurement of volume expansion, brake fluid was used as a low volume expansion liquid to fill in any air gaps between the test tube walls and the wax pellet. As the temperature of the test tube was increased by a Bunsen burner, the height of the brake fluid was measured with respect to the temperatures. At higher temperatures, the level of brake fluid increased, indicating that the wax substance volumetrically increased with increasing temperature. Expansion curves were generated based on data recorded from the experiments. Further testing was done to ensure that the volumetric expansion of the brake fluid would not have an effect on the volume measurements of the waxes.
Moving forward from a single piston design, a ring piston design was developed in order to allow for a conduit to exist through the center of the connectivity. A prototype disruptor was developed with a hollow tube through the center, in which electronic pin connectors can be placed. The body of the prototype was machined out of aluminum and copper metal. Other components of the prototype were 3-D printed using a Stratasys Objet30 printer, which prints high resolution UV-cured plastic components. Combining machining and 3-D printing allowed for a prototype of a ring-piston style connectivity to be developed. Paraffin wax was used as the thermoexpansive substance enclosed within the ring piston prototype. Testing of the ring piston prototype showed successful expansion and success of prototype connectivity components being disrupted before an unsafe event occurred.
Various thermoexpansive substances were experimented with in order to find a substance which exhibits the highest level of expansion at a temperature within the range of 150 degrees Celsius to 200 degrees Celsius. A relationship must exist where the expansion point of the thermoexpansive material can be tuned to be well below the melting point of the housing of the material which encapsulates the thermoexpansive material. Because the temperature range at which the connectivity disruptor is supposed to be activated is known, ABS and polypropylene plastics were found to have melting points of close to 230 degrees Celsius. Because of the melting temperatures, ABS and polypropylene were utilized to fabricate the initial prototypes. Different types of casing materials can be used for the connectivity disruptor as long as their structural integrity is maintained at the disruption temperature.
The preferred embodiment of the connectivity disruptor is produced using an injection molded polymer with a softening point well above the expansion temperatures of the thermoexpansive substances. Injection molded prototypes have been produced using ABS and polypropylene plastics and a hand-operated injection molding machine. Molds for the injection molding machine were produced using the same 3-D printer which was utilized to produce initial prototypes. It was found that accurate injection molded parts can be produced using the 3-D printed molds, allowing for small scale production of interchangeable parts. Several motivations served the motion towards injection molding the prototypes. Firstly, 3-D printers capable of printing in high temperature materials are unable to print at the resolution which would be desired in a finalized design. Secondly, injection molding opens a wider variety of polymeric materials which can be chosen for use in the construction of the connectivity disruptor. Thirdly, movement towards injection molding was done in order to better understand the design of the thermohydraulic disruptor from an industrial high volume production standpoint.
The present invention has been described in terms of the preferred embodiment, and it is recognized that equivalents, alternatives, and modifications (aside from those expressly stated), are possible and within the scope of the appending claims.
While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. For example, in the case of electrical conduits, the connectivity may be within a junction box, a panel, or electronic assembly. As another example, in the case of chemical conduits, the connectivity may be gate valves within a distribution system. Additionally, the force of the thermovolumetric substance can be augmented by means such as, but not limited to, a spring or force generated by a thermos-kinetic substance. In another embodiment, the disruptor could be configured with a means to produce a signal indicative of the state of the continuity and/or disruption such as, but not limited to, an electronic signal, a semaphore, or release of a marker substance such as, but not limited to, a fluorescent dye. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention.
The previous description of specific embodiments is provided to enable any person with ordinary skill in the art to make or use the present invention. The various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without the use of the inventive faculty.
A person with ordinary skill in the art would understand that the forces generated by the thermovolumetric substance could be augmented by forces such as produced by a spring, a thermokinetic substance or other energetic component.
DefinitionsDirect Current (DC): an electric current flowing in one direction only.
Alternating Current (AC): an electric current that reverses its direction many times a second at regular intervals, typically used in power supplies.
Connectivity: Connectivity as used herein is a general term that includes wiring and associated attachment means used for the purpose of conducting fluids, electrical current (AC or DC), or combinations thereof. The connectivity components are sometimes called connectors, plugs, terminals, electrodes, receptacles, and junction boxes among other names. Systems which are in connectivity are in a state of a closed circuit.
Connector: Connector as used herein is a general term for a connectivity device which bridges two ends of an electrical or fluidic system.
Conductor or Conduit: A conductor or conduit as used herein is a general term for a mechanism for transporting energy or substances over distances.
Substance or Material: The terms substance and material as used herein are interchangeable.
Thermohydraulic material: Thermohydraulic material as used herein is a general term for a substance which produces a hydraulic force as a result of heating in an enclosed chamber.
Thermovolumetric substance, thermoexpansive substance, and thermohydraulic substance: thermovolumetric substance, thermoexpansive substance, and theremohydraulic substance as used herein are interchangeable as a general term for a substance that exhibits volumetric expansion above or within a certain temperature range.
Thermokinetic substance and thermoenergetic substance: thermokinetic substance and thermoenergetic substance as used herein are interchangeable as a general term for a combination of chemically reactive substances such as explosives, pyrotechnic compositions, propellants, gun powders, and fuels that decompose with release of energy in the form of gas and heat byproducts when exposed a sufficient amount of time at or above a certain temperature.
Fire suppressant: Fire suppressant as used herein refers to substances that inhibit combustion.
Unsafe condition: An unsafe condition as used herein is a hazardous situation that precedes an unsafe event.
Hazardous condition: A hazardous condition as used herein is an unsafe situation that precedes a hazardous event.
Electric arc or arc discharge: Electric arc or arc discharge as used herein is a general term for an electrical breakdown of a gas that produces an ongoing high temperature plasma discharge, resulting from a current through normally nonconductive media such as air.
Thermal energy: Thermal energy as used herein is a general term for the internal energy present in a system by virtue of its temperature.
Thermal expansion: Thermal expansion as used herein occurs when an object expands and becomes larger due to a change in the object's temperature.
Expansive energy: Expansive energy as used herein pertains to the power related to a pressurized fluid or viscous substance used to accomplish machine motion. The pressure can be relatively static (such as reservoirs) or in motion though tubing or hoses.
Non-reactive substance: Non-reactive substance as used herein is a general term for a substance that is suitable for conducting a certain chemical.
Pro-Active: Pro-Active as used herein is a general term for being preventive; e.g., taking action based on diagnosing a pre-condition.
Photovoltaic (PV): refers to a method for generating electric power by using solar cells to convert energy from the sun into a flow of electrons. Photons of light excite electrons into a higher state of energy, allowing them to act as charge carriers for an electric current.
A person with ordinary skill in the art would understand that embodiments of the present invention can include different arrangements of cavities and channels through which the hydraulic substance flows, depending on the functionality required. Further, that while the embodiments presented in this application focus on preventing arc-faults in electrical power systems, the present invention can be applied in any situation where high temperature hazards can result in loss of life and destruction of property. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein and as defined by the following claims.
Claims
1. An apparatus for disruption of a flow of an Ohmic heat in an electrical connectivity comprising:
- two or more electrical conductors to conduct a flow of an electrical current;
- a connector configured to join the two or more electrical conductors;
- a substance selected from fluid substances that generate a force when heated;
- a cavity within the connector for confining the substance, and
- wherein the Ohmic heat generated by the flow of an electrical current via the two or more electrical conductors heats the substance sufficiently to generate an amount of the force sufficient to separate the two or more electrical conductors disrupting the flow of the Ohmic heat and the electrical current.
2. An apparatus for annunciating a hazardous condition in a connectivity comprising:
- a connector to join two or more electrical conductors,
- a fluid thermovolumetric substance for generating a force,
- a cavity within the connector for enclosing the thermovolumetric substance, and
- a means for generating a signal indicative of need to disrupt the connectivity.
3. The apparatus of claim 2 further comprising a means for causing disruption of the connectivity upon receiving the signal.
4. The apparatus of claim 2, wherein energy to power the constituents which require energy conducted by the apparatus.
5. The apparatus of claim 2, wherein heating of the fluid thermovolumetric substance forces a disruption of the connectivity.
6. The apparatus of claim 1 further comprising a thermokinetic substance to augment the force.
7. An apparatus for a permanent mitigation of an overheat condition in an electrical connectivity comprising:
- a connectivity component having a maximum temperature rating configured in a manner for joining two or more electrical conductors comprising:
- a separable conductive guide for conducting a flow of an electrical current comprising:
- two or more joined portions wherein at least one portion comprises a corrodible electrically conductive material;
- a substance for producing a hydraulic force selected from fluid substances which upon heating produce force when contained within an enclosed space;
- an assembly for the purpose of freeing the two or more joined portions comprising:
- a first part having a first space for holding the substance and a remaining space; and
- a second part configured to fit into the remaining space of the first part in a manner to convert the hydraulic force produced by a heating of the substance into a mechanical force for the purpose of disconnecting the two or more joined portions; and
- wherein a corrosion causes electrical resistance to a flow of an electrical current of the at least one of the two or more electrically conductive parts and produces an Ohmic heat, and wherein the electrical resistance caused by corrosion in combination with the flow of the electrical current increases the associated Ohmic heat above the maximum temperature rating of the connectivity heats the substance producing a sufficient mechanical force to disconnect at least one of the two or more electrically conductive parts thereby ceasing current flow in the connectivity.
Type: Application
Filed: Apr 8, 2019
Publication Date: Jan 2, 2020
Inventors: Kenneth G. Blemel (A, NM), Kenneth D. Blemel (Albuquerque, NM), Benjamin Allen Boone (Bard, NM), Jesse Min-Tze Adamczyk (Altadena, CA), Lara Rose Draelos (Albuquerque, NM), Mariana Flores-Olivas (Roswell, NM), Matthew James Hinton (Socorro, NM)
Application Number: 16/377,982