Patent Application
20120069477
The embodiments described herein relate generally to power equipment protection devices and, more particularly, to apparatus that include adjustable electrode assemblies.
Known electric power circuits and switchgear generally have conductors that are separated by insulation, such as air, or gas or solid dielectrics. However, if the conductors are positioned too closely together, or if a voltage between the conductors exceeds the insulative properties of the insulation between the conductors, an arc can occur. The insulation between the conductors can become ionized, which makes the insulation conductive and enables formation of an arc flash.
An arc flash is caused by a rapid release of energy due to a fault between two phase conductors, between a phase conductor and a neutral conductor, or between a phase conductor and a ground point. Arc flash temperatures can reach or exceed 20,000° C., which can vaporize the conductors and adjacent equipment. Moreover, an arc flash can release significant energy in the form of heat, intense light, pressure waves, and/or sound waves, sufficient to damage the conductors and adjacent equipment. However, the current level of a fault that generates an arc flash is generally less than the current level of a short circuit, such that a circuit breaker may not trip or exhibits a delayed trip unless the circuit breaker is specifically designed to handle an arc fault condition. Although agencies and standards exist to regulate arc flash issues by mandating the use of personal protective clothing and equipment, there is no device established by regulation that eliminates arc flash.
Standard circuit protection devices, such as fuses and circuit breakers, generally do not react quickly enough to mitigate an arc flash. One known circuit protection device that exhibits a sufficiently rapid response is an electrical “crowbar,” which utilizes a mechanical and/or electro-mechanical process by intentionally creating an electrical “short circuit” to divert the electrical energy away from the arc flash point. Such an intentional short circuit fault is then cleared by tripping a fuse or a circuit breaker. However, the intentional short circuit fault created using a crowbar may allow significant levels of current to flow through adjacent electrical equipment, thereby still enabling damage to the equipment.
Another known circuit protection device that exhibits a sufficiently rapid response is an arc containment device, which creates a contained arc to divert the electrical energy away from the arc flash point. At least some known arc containment devices include a plurality of electrodes that are each threaded directly into a corresponding electrode holder. These electrodes cause electrical energy to concentrate at the interface point with the electrode holder, i.e., at the thread, which creates a structurally weak point that can cause failure during use. Moreover, this concentration of energy at the interface point can cause the electrode to become welded or melted to the electrode holder, which requires replacement of both the electrode and the electrode holder after use. Furthermore, because of tolerances in the manufacture of such threaded electrodes, it can be difficult to position these electrodes to obtain consistent results.
In one aspect, a circuit protection device is provided for use with a circuit that includes at least one conductor includes at least one phase electrode assembly that is electrically coupled to the at least one conductor, wherein the at least one phase electrode assembly comprising an adjustable electrode assembly. The circuit protection device also includes a conductor base comprising at least one isolation area sized to secure the adjustable electrode assembly therein, and a conductor cover coupled to the conductor base and including at least one isolation channel, wherein the adjustable electrode assembly extends at least partially through the at least one isolation chamber.
In another aspect, an electrical isolation structure is provided for use with a circuit protection device that includes a plurality of phase electrode assemblies each having an electrode movably coupled to an electrode holder, a phase strap, and a vertical riser. The electrical isolation structure includes a conductor base including a plurality of isolation areas each sized to secure a respective phase strap therein, wherein the conductor base is configured to provide electrical isolation between the phase straps of the plurality of phase electrode assemblies. The electrical isolation structure also includes a conductor cover coupled to the conductor base and including a plurality of isolation channels, wherein a respective electrode holder extends at least partially through a respective isolation chamber of the plurality of isolation channels to provide electrical isolation between a plurality of the electrode holders of the plurality of phase electrode assemblies.
In another aspect, a method is provided for assembling a circuit protection device for use with a circuit that includes at least one conductor. The circuit protection device includes a conductor base having at least one isolation area, a conductor cover having at least one isolation channel, and at least one electrode post assembly having an electrode holder and an electrode that is secured within an opening defined in the electrode holder. The method includes inserting the electrode into the opening, securing the electrode within the opening, securing the at least one electrode post assembly within the at least one isolation area, coupling the conductor cover to the conductor base such that the at least one electrode post assembly extends at least partially through the at least one isolation channel, and electrically coupling the at least one electrode post assembly to the at least one conductor.
Exemplary embodiments of apparatus and methods of assembly for use with a circuit protection device are described hereinabove. These embodiments facilitate adjusting a distance between electrodes in a circuit protection device, such as an arc containment device. Adjusting the distance, or air gap, between the electrodes enables an operator to setup the circuit protection device in a manner that best suits the environment in which the circuit protection device is to be used. For example, the distance between the electrodes may be set based on the system voltage. Moreover, the embodiments described herein enable replacement of the electrodes after use, which are among the lowest-cost elements of the circuit protection system.
During operation, controller 106 receives signals from one or more sensors (not shown) for use in detecting an arc flash within an equipment enclosure (not shown). The sensor signals may correspond with current measurements through one or more conductors of the circuit, voltage measurements across conductors of the circuit, light measurements in one or more areas of the equipment enclosure, circuit breaker settings or statuses, sensitivity settings, and/or any other suitable sensor signal that indicates an operation status or operating data relating to the power distribution equipment. Controller 106 determines whether an arc flash is occurring or is about to occur based on the sensor signals. If an arc flash is occurring or is about to occur, controller 106 initiates a contained arc flash within containment section 102 and transmits a signal to, for example, a circuit breaker, that is electrically coupled to the circuit at risk of the arc flash. In response to the signal, a plasma gun (not shown) emits an ablative plasma between a plurality of electrodes (not shown in
Electrical isolation structure 200 also includes a conductor cover 228 coupled to conductor base 204. Specifically, conductor cover 228 includes a first end 230, an opposite second end 232, a top surface 234, and a sidewall 236 having a bottom surface 238. Conductor cover 228 is coupled to conductor base 204 via a plurality of coupling mechanisms, such as screws or bolts (not shown), that each extends through a respective hollow post 222 and is secured in conductor cover 228. When conductor cover 228 is coupled to conductor base 204, bottom surface 238 is substantially flush with top surface 216. In addition, electrical isolation structure 200 includes a vertical barrier 240 coupled to conductor base 204 and conductor cover 228. Specifically, vertical barrier 240 includes a front surface 242 and an opposite rear surface 244, as well as a top surface 246 and an opposite bottom surface 248. Vertical barrier 240 is coupled to conductor base 204 and conductor cover 228 such that a portion of vertical barrier front surface 242 is positioned in contact with conductor base second end 208 and conductor cover second end 232. Vertical barrier 228 also includes a plurality of recesses 250 that are formed in rear surface 244. Each recess 250 is sized to enable a vertical riser (not shown in
In the exemplary embodiment, circuit protection device 100 also includes a plurality of electrode assemblies 256 that each includes an electrode 258 and an electrode holder 260. Conductor cover 228 includes a plurality of isolation channels 262 that are each sized to house a respective electrode assembly 256 to provide electrical isolation between electrode assemblies 256. Each isolation channel 262 is defined by a plurality of sidewalls 264. Specifically, isolation channels 262 provide electrical isolation between electrode holders 260. Moreover, isolation channels 262 provide electrical isolation between electrodes 258 and the phase straps that are positioned between conductor cover 228 and conductor base 204. Furthermore, conductor cover 228 includes a plasma gun aperture 266 that is defined by a circular sidewall 268. Plasma gun aperture 266 is sized to enable a plasma gun (not shown) to extend at least partially therethrough. When activated, the plasma gun emits an ablative plasma that enables arc formation between electrodes 258.
Each phase strap 302 is coupled to a vertical riser 322. In the exemplary embodiment, each vertical riser 322 is composed of an electrically conductive material, such as copper. However, any suitably conductive material may be used. Moreover, each vertical riser 322 includes a front surface 324, an opposite rear surface 326, a top end 328 having a top surface 330, and an opposite bottom end 332 having a bottom surface 334. Vertical riser 322 is coupled to phase strap 302 such that vertical riser bottom surface 334 is positioned substantially flush with phase strap top surface 308 at phase strap second end 306 to facilitate transfer of electrical energy from vertical riser 322 to phase strap 302. In the exemplary embodiment, vertical risers 322 facilitate racking circuit protection device 100 into a bus (not shown) while powered and/or unracking circuit protection device 100 from the bus while powered. In an alternative embodiment, phase electrode assembly 300 does not include vertical risers 322. In such an embodiment, each phase strap 302 is coupled, such as coupled directly in contact with, a bus.
Moreover, as shown in
Phase electrode assembly 300 enables electrical energy to be transferred from a conductor to a respective electrode 258 via a current path. In the exemplary embodiment, the current path includes spring cluster 340, cluster support 336, vertical riser 322, phase strap 302, electrode holder 260, and electrode 258. In an alternative embodiment, phase electrode assembly 300 does not include vertical riser 322, cluster support 336, and/or spring cluster 340. In such an embodiment, the current path includes phase strap 302, electrode holder 260, and electrode 258.
In the exemplary embodiment, electrode assembly 256 also includes an electrode holder 260 that is composed of an electrically conductive material, such as copper. However, electrode holder 260 may be composed of any other conductive material that also prevents thermal issues between two dissimilar materials, such as between electrode 258 and electrode holder 260. Electrode holder 260 includes a top surface 408 and an opposite bottom surface 410. Electrode holder 260 also has a plurality of side surfaces, including a first side surface 412, an opposite second side surface 414, a first end surface 416, and an opposite second end surface 418. A plurality of mounting apertures 420 are defined through electrode holder 260 from top surface 408 through bottom surface 410. A coupling mechanism, such as a screw or bolt (not shown), that is sized to be inserted through a corresponding mounting aperture 420 is used to mount electrode holder 260 to phase strap top surface 308 (shown in
Moreover, electrode holder 260 includes a clamp portion 424 that secures electrode 258. More specifically, clamp portion 424 enables a position of electrode 258 to be adjusted in a first direction 426 to create a smaller electrode gap between electrodes 258 as shown in
Exemplary embodiments of apparatus for use in devices for protection of power distribution equipment are described above in detail. The apparatus are not limited to the specific embodiments described herein but, rather, operations of the methods and/or components of the system and/or apparatus may be utilized independently and separately from other operations and/or components described herein. Further, the described operations and/or components may also be defined in, or used in combination with, other systems, methods, and/or apparatus, and are not limited to practice with only the systems, methods, and storage media as described herein.
Although the present invention is described in connection with an exemplary power distribution environment, embodiments of the invention are operational with numerous other general purpose or special purpose power distribution environments or configurations. The power distribution environment is not intended to suggest any limitation as to the scope of use or functionality of any aspect of the invention. Moreover, the power distribution environment should not be interpreted as having any dependency or requirement relating to any one or combination of components illustrated in the exemplary operating environment.
The order of execution or performance of the operations in the embodiments of the invention illustrated and described herein is not essential, unless otherwise specified. That is, the operations may be performed in any order, unless otherwise specified, and embodiments of the invention may include additional or fewer operations than those disclosed herein. For example, it is contemplated that executing or performing a particular operation before, contemporaneously with, or after another operation is within the scope of aspects of the invention.
When introducing elements of aspects of the invention or embodiments thereof, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
