Electricity: electrothermally or thermally actuated switches – Electrothermally actuated switches – Fusible element actuated
Reexamination Certificate
2000-04-28
2002-05-21
Picard, Leo P. (Department: 2835)
Electricity: electrothermally or thermally actuated switches
Electrothermally actuated switches
Fusible element actuated
C337S176000, C337S171000, C337S292000, C361S104000
Reexamination Certificate
active
06392526
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to fuse cutouts used with power distribution systems as protective devices against over current. In particular, the fuse cutout includes a mounting assembly, a pivotally movable fuseholder assembly received in the mounting assembly, and a spring member for biasing the fuseholder toward an open drop-out position.
BACKGROUND
The primary purpose of a fuse cutout is to provide protection for power distribution systems and the various apparatus on those power lines such as transformers and capacitor banks. An over current in the system can occur under various conditions, such as an animal or tree contacting the power lines or more than one power line contacting each other. The fuse cutout acts to interrupt the current, and then the fuseholder of the cutout “drops out”, thereby preventing the voltage from being impressed across the fuseholder and providing a visual indication of operation to the utility line crew.
Problems have occurred with the prior art cutouts in corrosive environments. Specifically, corrosive build up on the moving parts of the cutout cause friction which prevents the cutout from dropping out when the fuse element melts. Thus, the voltage is not removed from across the fuse holder. In addition, external flashovers can result from the cutout not dropping out. Moreover, the fuse cutout itself is typically burned up and damaged.
The present fuse cutouts do not provide a manner of either overcoming or reducing the friction due to the corrosion build up. In addition, the present fuse cutouts cannot ensure a consistent drop-out of the fuseholder upon each occurrence of a melted fuse element. Furthermore, the prior art cutouts may fail to provide protection against damage to the cutout.
Examples of prior art fuse cutouts are disclosed in the following U.S. Pat. No.: 1,939,371 to Spurgeon; U.S. Pat. No. 2,174,476 to Pittman et al.; U.S. Pat. No. 2,464,565 to Evans et al.; and U.S. 4,540,968 to Kato et al.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a fuse cutout that increases the forces for overcoming the friction resulting from corrosion simply and inexpensively.
Another object of the present invention is to provide a fuse cutout that reduces the friction resulting from the build up of corrosion between moving parts of the fuse cutout.
A further object of the present invention is to provide a fuse cutout with a mechanical assist, such as a spring member, for overcoming the friction due to corrosion.
Yet another object of the present invention is to provide a fuse cutout that provides a consistent drop-out of the fuseholder upon the occurrence of an over current.
A yet further object of the present invention is to provide a fuse cutout that prevents damage to the cutout.
The foregoing objects are basically attained by providing a fuse cutout for connection to a power source comprising, a mounting having upper and lower support members extending from opposing ends of the mounting, respectively. A holder member is fixedly attached to the lower support of the mounting. A pivot member is received in the holder member at a first pivot point, the pivot member being movable between first and second positions. A fuseholder has upper and lower ends, the lower end being pivotally attached to the pivot member at a second pivot point, the fuseholder being movable between closed and open positions corresponding to the first and second positions of the pivot member, respectively. A first biasing member is disposed between the pivot member and the lower end of the fuseholder at the second pivot point, biasing the pivot member toward the second position.
The foregoing objects are also attained by a fuse cutout comprising a mounting having upper and lower support members extending from opposing ends of the mounting, respectively. A holder member is fixedly attached to the lower support of the mounting, the holder member having a contact portion. A pivot member is received in the holder member at a first pivot point and is movable between first and second positions. The pivot member has a planar cam surface engaging the contact portion of the holder member with a first pressure when the pivot member is in the first position, and engages the contact portion with a second pressure when the pivot member is in the second position, the second pressure being substantially less than the first pressure. A fuseholder has upper and lower ends, the lower end being pivotally attached to the pivot member at a second pivot point.
By designing the fuse cutout in this fashion, the friction resulting from corrosion build up can be overcome. Thus, the fuse cutout of the present invention has provides a consistent drop-out of the fuseholder upon each occurrence of an over current.
Other objects, advantages and salient features of the invention will become apparent from the following detailed description which taken in conjunction with annexed drawings, discloses a preferred embodiment of the present invention.
REFERENCES:
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patent: 2074913 (1937-03-01), Johnson
patent: 2088415 (1937-07-01), Heinrich
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Hubbell Power Systems Catalog titled Cutout and Cutout-Arrester Combinations; pp. 10A-1 to 10A-7; Nov. 1996.
Brown Robert A.
Clark Daren A.
Roberts Gerald B.
'Hubbell Incorporated
Bicks Mark S.
Goodman Alfred N.
Hoffman Tara L.
Picard Leo P.
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