The technical field generally relates to interrupting equipment in power distribution systems, and more particularly relates to fuse mountings used in connection with such systems.
Power distribution systems include a variety of subsystems designed to protect transformers and other components from overload conditions and current surges. One such system is the power fuse assembly or fuse cut-out, which is a protection device that is part fuse, part switch, and which is often used in connection with overhead feeder lines.
A power fuse assembly generally includes a fuse mounting that supports a fuse unit and associated fittings, all of which are rotatably coupled to the fuse mounting via a hinge assembly at its lower end. The fuse unit includes a fusible element that, during an overload event, deteriorates and then mechanically separates, causing the fuse unit to disconnect the electrical circuit by dropping the top end of the fuse unit out of the fuse mounting in a rotational manner. Deterioration of the fusible element during an overload event produces a significant amount of exhaust gases, which in some cases may be captured by a silencer assembly mounted to the bottom of the fuse cut-out. These exhaust gases may be on the order of many thousands of degrees Fahrenheit and exhibit a velocity on the order of the speed of sound.
Currently known exhaust systems for power fuse assemblies may be unsatisfactory in a number of respects. For example, such systems may not divert the exhaust in a desirable direction—e.g., away from a linemen or other individual in the vicinity of the power fuse assembly. Diversion of such gases is known to be difficult, since it is important to reduce any pressure drops that might arise in the path of the exhaust gases. Furthermore, currently known silencer assemblies may be too large to swing freely through the normal hinge assembly.
Accordingly, there is a need for accommodating the exhaust produced by fuse units of the type used in conjunction with power fuse assemblies. Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.
The exemplary embodiments will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein:
A power fuse assembly in accordance with one embodiment includes a fuse mounting, a fuse unit, and a hinge assembly. The fuse unit is configured to carry current from a line connection to a load connection. The hinge assembly is configured to be removeably coupled to the fuse unit and to allow rotation of the fuse unit relative to the fuse mounting. The hinge assembly includes an inlet having a first orientation and configured to accept incoming gases produced by the fuse unit in response to an overload event. The hinge assembly also includes an outlet in fluid communication with the inlet and having a second orientation that is not equal to the first orientation. A diverter component is disposed between the inlet and the outlet and configured to guide the flow of gases from the inlet in the first orientation and to the outlet in the second orientation.
A hinge assembly in accordance with one embodiment is configured to be removeably coupled to a fuse unit of a power fuse assembly. The hinge assembly includes an inlet having a first orientation and configured to accept incoming gases produced by the fuse unit in response to an overload event. The hinge assembly also includes an outlet in fluid communication with the inlet and having a second orientation that is not equal to the first orientation. A diverter component is disposed between the inlet and the outlet and configured to guide the flow of gases from the inlet in the first orientation and to the outlet in the second orientation.
The upper end fitting 122 is mechanically and electrically coupled (e.g., via an interference fit or latch) to upper contact assembly 121 as shown. In overhead applications, fuse mounting 101 is generally mounted at a slightly forward-tipping angle (e.g., about 20-degrees) such that longitudinal axis A-A is not strictly normal to the plane of the ground or other substrate below fuse mounting 101. In that regard, front region 120 as well as the space below front region 120 may together be referred to herein as the space in “front” of fuse mounting 101 during normal operation, a location that an operator may in part occupy during maintenance or installation of fuse mounting 101 and/or fuse unit 102.
During an overload event, a fusible element (not shown) within the fuse tube 105 separates and fuse unit 102 is released (rotationally with respect to hinge pivot 108) out of fuse mounting 101 and toward front region 120, thereby creating an open circuit and providing a visual cue (via hanging fuse unit 102) that power fuse assembly 100 has experienced a fault condition.
The nature and operation of conventional fuse mountings, fuse elements, cut-outs, and the like, are known in the art, and need not be further described herein. In that regard, the subject matter described herein may be used in a wide variety of power fuse assemblies. One such assembly, for example, is the SMD-20 Power Fuse manufactured by S&C Electric Company. The invention is not so limited, however.
With continued reference to
In accordance with the illustrated embodiment, hinge assembly 104 also includes a lift ring 116 as well as cap component or cap 112 that is rotateably coupled to hinge assembly 104 at a pivot 114. Cap 112, as described in further detail below, is configured (e.g., via its geometry and weight distribution) to engage and close off outlet port 110 when fuse unit 102 is substantially inverted, but to remain open (as shown in
Silencer component 210 may include any suitable structure capable of guiding and emitting the exhaust gases 212 produced during an overload event. In that regard, silencer component 210 will generally include labyrinthine or similar internal structures that lead to (are in fluid communication with) a series of openings (not shown) at the bottom of silencer component 210. Such silencers components are known in the art, and need not be further described in detail herein.
With continued reference to
Thus,
Also shown in
With continued reference to
While opening 310 may be oriented such that escaping gases move at approximately a 45 degree downward angle relative to the orientation of
As can be seen, the direction of the incoming exhaust gases 810 is different from the direction of the outgoing exhaust gases 812 by a predetermined angle as discussed above in connection with
In general, diverter vane 805 has an upstream portion 831 and a downstream portion 832, as shown. The leading edge 803 of diverter vane 805 effectively splits the incoming exhaust gases into two parallel flows (indicated generally by regions 841 and 842) before those flows are recombined prior to or at the outlet region 813.
Diverter vane 805 may have a variety of shapes. In the illustrated embodiment, diverter vane 805 is illustrated as generally airfoil-shaped; having opposing surfaces 851 and 852, and has a profile that substantially follows the contours of surfaces 821 and 822. That is, to the extent that diverter vane 805 is an airfoil, it has a mean camber line 850 that has substantially the same arcuate shape as one or more of surfaces 821 and 822. In the illustrated embodiment, diverter vane 805 is substantially concave facing surface 822 (adjacent surface 852), and substantially convex facing surface 821 (adjacent surface 851).
Redirecting exhaust gasses 810, 812 employs a pressure gradient produced by a pressure against the flow on one side and a lowered pressure at the other side of the flow. To provide added pressure surfaces and low pressure relief sides, the flow is split into two (or more) flows such that each division of flow has a high and low pressure side prior to rejoining at the final exhaust outlet 813. One divided flow 842 is between surface 852 and surface 822. Surface 852 presses against the flow 842, causing a sideways pressure on the gasses impinging on it while surface 822 retreats from the flow with a turbulent boundary layer causing a lower pressure to that side allowing the gasses to follow the radius of the curve. Similarly, gasses in flow 841 are situated between high pressure caused by surface 821 and a lower pressure following surface 851 of the web. Use of a simple “elbow” shape with no division would in most instanced cause decoupling from the lower pressure surface, resulting in a swirling “eddy” that would reduce the effective area of the port and cause a back-pressure which would reduce the ability of the fuse to interrupt the rated load.
In accordance with another aspect, diverter vane 805 may be used as a “wear indicator.” That is, visual inspection of its dimensions (e.g., the thickness of material between surfaces 851 and 852) will generally reveal the expected remaining lifetime of bend portion 800 (and thus the hinge assembly in which it is incorporated). The correlation of observable thickness to expected lifetime may be established in a variety of ways, including computer modeling and/or empirical testing. In addition, the observed condition of walls 801 and 802 may also be used as a gauge of expected lifetime, based on, for example, the extent to which burn-through marks are observed on the inner surfaces 821 and 822.
While
Diverter vane 805 may be manufactured using a variety of methods and may be formed from any material or combination of materials configured to withstand the pressure and temperature of the exhaust gases. In some embodiments, diverter vane 805 includes a metal alloy that is cast as an integrated part of the hinge assembly. In other embodiments, diverter vane 805 is a ceramic or composite material.
While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to be models or otherwise limit the scope, applicability, or configuration of the disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the disclosure as set forth in the appended claims and the legal equivalents thereof.
This application claims the benefit of U.S. Provisional Application No. 62/341,194 filed on May 25, 2016, the entire disclosure of which is incorporated herein by reference.
Number | Date | Country | |
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62341194 | May 2016 | US |