Patent Grant
7160142
The present invention relates generally to the field of grounding devices. More particularly, this invention relates to enhancements in grounding devices for securing a connection between a potentially energized apparatus and a ground point, while increasing the ease of use of such devices.
Typically, the distribution of power begins at a power generation facility, such as a power plant. As the power leaves the power plant, it enters a transmission substation, where a transformer converts it up to extremely high voltages for long-distance transmission. Then the power is transmitted over high-voltage transmission lines and is later converted down to distribution voltages that will allow it to be useful to ordinary residential or commercial customers. After the power is converted, the power is transmitted over power lines that typically lead to a switchgear. The switchgear sectionalizes the power amongst various customers in a particular subdivision. The power is then sent to another transformer and reduced from 7,200 volts, which is the voltage typically delivered over a distribution bus line, down to the 240 volts necessary for ordinary residential or commercial electrical service.
Grounding clamps are used to connect the mating interface of a power transmission or power distribution apparatus to a nearby ground point. Such a grounding operation is necessary to perform maintenance operations on the mating interface of a power transmission or power distribution apparatus. For instance, examples of such power transmission or power distribution apparatuses could be in the form of a transformer, a switchgear, a sectionalizing cabinet, or other similar equipment performing a like function. For example, a transformer's general purpose is to convert the power transmitted from an energy source to a receiving device to a useful level for service or distribution. In many cases, a transformer reduces high-distribution voltages down to appropriates levels for residential or commercial customers. In other cases, a transformer can boost the generated voltage up to extremely high levels for long-distance transmission. In both cases, such transformers invariably require maintenance. In performing maintenance to a transformer, the mating interfaces, generally, should be grounded.
Power distribution apparatuses typically distribute power through mating interfaces such as universal wells and spades. The universal wells distribute high-voltage power, while the spades distribute low-voltage power. Such apparatuses typically have several spades. In most cases, a spade is torqued into the low-voltage bushing wells, and its primary purpose is to distribute low-voltage power to customers. For example, each spade can send power to several customers in a subdivision. However, when a spade requires maintenance or when an additional customer requires a connection to the apparatus, an operator typically grounds the spade in order to perform such operations.
The process of grounding the mating interface of a power apparatus typically involves a line-crew operator connecting the clamp's grounding cable to a ground rod and mounting the clamp on the spade. Typically, the clamps are provided as C-clamps, with a C-shaped body and a rod inserted through an opening in the C-shaped body. The rod can be turned primarily at one end, in order to increase the pressure exerted on the mating interface by the clamp. When mounting the clamp on a mating interface, the operator typically clamps the mating interface at an angle, referred to as the grasping angle, in order to achieve the necessary surface contact with the mating interface. The grasping angle is the angle of approach for the gripping surfaces of the clamp to grasp a mating interface. Due to the confinements of the grasping angle, it is necessary that an operator work in close proximity to the frontplate or tank wall of the power apparatus to attach or remove the clamp from the mating interface. Nonetheless, it is desirable for an operator to be able to maintain distance from the frontplate or tank wall of the power apparatus when performing such operations.
Accordingly, it should be advantageous to provide a grounding clamp configured to allow for easier removal of the grounding clamp at a distance from the frontplate or tank wall of a power transmission or power distribution apparatus. It would be desirable to provide a grounding clamp and method or the like of a type disclosed in the present application that includes any of these or other advantageous features. It should be appreciated, however, that the teachings herein may also be applied to achieve devices and methods that do not necessarily achieve any of the foregoing advantages but rather achieve different advantages.
In accordance with one embodiment of the present invention, a grounding clamp comprises a rigid member with a first end and second end and a moveable member inserted through the second end of the rigid member. The moveable member repositions in relation to the first end of the base for clamping with the first end of the base. The first end of the rigid member is configured such that it is not perpendicular to the axis of motion of the moveable member.
Still other advantages of the present invention will become readily apparent to those skilled in this art from review of the enclosed description, wherein the preferred embodiment of the invention is disclosed, simply by way of the best mode contemplated, of carrying out the invention. As it shall be understood, the invention is capable of other and different embodiments, and its several details are capable of modifications in various respects, all without departing from the invention. Accordingly, the figures and description shall be regarded as illustrative in nature, and not as restrictive.
Referring to
Additionally, the second end 15 of the C-shaped member 2 intersects the opposite end of mid-section 14. The angle created by this intersection is approximately ninety degrees (90°) in the illustrated embodiment, although other configurations may be used. Although C-shaped member 2 is herein disclosed as multiple elements, it may be molded, welded, or cast as a singe unit to achieve the same result. Grounding cable 17 is attached to C-shaped member 2. Grounding cable 17 is connected to a nearby ground point for a secure connection to ground.
First gripping surface 9 is formed on the inner surface of the first end 13 of C-shaped member 2. Since it is formed to first end 13, first gripping surface 9 is also correspondingly angled between one-hundred degrees (100°) and one hundred and eighty degrees (180°), in relation to the intersection of first end 13 and mid-section 14. First gripping surface 9 can be formed to the inner surface by most typical means of assembly including, without limitation, molding, welding, casting, gluing, bolting, screwing, fastening, clamping, or being formed integrally with C-shaped member 2, although other arrangements may also be used. On the second end 15, rod 3 is inserted through an aperture in second end 15 of C-shaped member 2. Rod 3 has a first end and second end, whereon rod 3 has a torque ring 5 affixed to second end of rod 3, through which a live-line tool 21 may be attached, as shown in
As illustrated in
As mentioned, the angle created by the intersection of first end 13 and mid-section 14 is referred to as the grasping angle 19. Grasping angle 19 is angled between one-hundred degrees (100°) and one hundred and eighty degrees (180°). More specifically, grasping angle 19 is the angle of approach at which the gripping surfaces of grounding clamp 1 clinch a spade. Grasping angle 19 allows the operator to apply torque to rod 3, while standing a live-line tool's 21 distance away from a mating interface in a power apparatus 23.
Referring now to
Throughout the specification, numerous advantages of exemplary embodiments have been identified. It will be understood of course that it is possible to employ the teachings herein so as to without necessarily achieving the same advantages. Additionally, although many features are herein disclosed as multiple elements, it will be appreciated that such features could also be implemented by molding or casting processes to create the claimed feature as a singe unit or assembled as separate components to achieve the same result. Further, although certain methods are described as a series of steps which are performed sequentially, the steps generally need not be performed in any particular order. Additionally, some steps shown may be performed repetitively with particular ones of the steps being performed more frequently than others, when applicable. Alternatively, it may be desirable in some situations to perform steps in a different order than described.
Many other changes and modifications may be made to the present invention without departing from the spirit thereof.
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