Electricity: circuit makers and breakers – Interlocking – Between switches and housing
Reexamination Certificate
2000-06-29
2002-04-16
Friedhofer, Michael (Department: 2832)
Electricity: circuit makers and breakers
Interlocking
Between switches and housing
C200S043010, C200S043040, C200S043160, C200S050020, C200S331000
Reexamination Certificate
active
06373004
ABSTRACT:
BACKGROUND OF THE INVENTION
Technical Field
The present invention relates generally to switchgear cabinets for circuit breakers and, more particularly, to such cabinets for circuit breakers having handles that can be engaged with removable leverage arms. Specifically, the invention relates to a switchgear cabinet having a retainer for removably carrying a leverage arm that operatively engages a circuit breaker handle.
Background Information
Electric power distribution systems typically includes one or more circuit breakers that automatically interrupt current during specific overcurrent and under-voltage conditions, as well as other conditions. Such circuit breakers typically include a plurality of stationary contacts and a plurality of moveable contacts, the moveable contacts being pivotable into and out of electrical engagement with the stationary contacts. The circuit breaker is in an “on” condition when the moveable contacts are in electrical engagement with the stationary contacts, and in such condition electricity is permitted to flow through the circuit breaker. The circuit breaker is in an “off” condition when the moveable contacts are disengaged from the stationary contacts, and in such condition current is prevented from flowing through the circuit breaker.
Circuit breakers typically include a tripping mechanism that acts upon an overcurrent condition or other specified condition to rapidly separate the moveable contacts from the stationary contacts to place the circuit breaker in the “off” condition and stop the flow of current therethrough. After the circuit breaker has been “tripped” in such a fashion, it is desirable to return the circuit breaker to the “on” condition to restore power to the electrical circuit once the cause of the overcurrent or other specified condition has been identified and rectified.
The circuit breaker typically is disposed within a cabinet of a switchgear assembly. The circuit breaker itself typically includes a handle or knob that is operatively connected with the moveable contacts and that protrudes to the outside regions of the circuit breaker and beyond the housing of the switchgear cabinet to permit a technician or other appropriate personnel to manually move the contacts between the “off” and “on” conditions and vice versa as needed. Inasmuch as circuit breakers handling large currents typically require heavy springs to assist in the engagement and disengagement of the moveable contacts with the stationary contacts, the forces required to operate the handle or knob to move the moveable contacts between the “off” and “on” conditions and vice versa can be excessive.
Leverage arms exist for use in conjunction with certain circuit breakers and provide additional leverage to the technician for such a task. Such a leverage arm is mounted on the handle that is operatively connected with an operating mechanism that manually moves the moveable contacts between the “off” and “on” conditions. The leverage arm provides the technician with additional leverage to operate the operating mechanism, according to known principles.
Such leverage arms have not, however, been without limitation. Leverage arms typically protrude outwardly from switchgear cabinetry by a given distance and thus are subject to being broken off during the course of normal activities occurring in the vicinity of the cabinetry. Leverage arms additionally can cause injury to persons walking past the cabinet without observing the leverage arm protruding outwardly therefrom. While some leverage arms may be of a detachable configuration that allows the leverage arm to be selectively detached from the handle of the circuit breaker operating mechanism, such detachable handles are subject to being lost or stolen whereby the handles would be unavailable when needed to operate the circuit breaker. As such, a need exists for an apparatus and method for retaining a detachable leverage arm for a circuit breaker in close proximity with the circuit breaker where it will be available for use when needed, yet will not be subject to theft or other loss.
SUMMARY OF THE INVENTION
In view of the foregoing, a retention device for removable carrying a leverage arm on a housing of a switchgear cabinet includes a mounting member mounted on the housing and a tab extending outwardly from the mounting member. The leverage arm includes a head and a shank, the shank being slidably disposed in an opening formed in the tab. A cover is mounted on the housing, the cover being moveable between a closed position and an open position, the cover in the closed position retaining the head of the leverage arm between the cover and the tab, and thus resisting movement of the shank from the opening. The cover in the open position permits the leverage arm to be removed from the opening in the tab.
An aspect of the present invention is to provide a switchgear cabinet, the general nature of which can be stated as including a housing, a switch disposed in the housing, the switch including a handle, a cover mounted on the housing, the cover being movable between a closed position and an open position, the cover extending outwardly from the housing, a retention device mounted on the housing, a leverage arm removably carried by the retention device, the leverage arm being removably engagable with the handle, the cover in the closed position being structured to resist removal of the leverage arm from the retention device, and the cover in the open position being structured to permit removal of the leverage arm from the retention device.
Another aspect of the invention is to provide a retention device for removably carrying a leverage arm on a switchgear cabinet, the switchgear cabinet including a housing and a cover, the cover extending outwardly from the housing, in which the general nature of the retention device can be stated as including a mounting member, the mounting member being structured to be mounted on the housing of the switchgear cabinet, and a tab structured to extend outwardly from the housing.
Still another aspect of the present invention is to provide a method for controlling the removability of a leverage arm from a housing of a switchgear cabinet, the general nature of which can be stated as including the steps of providing a retention device mounted on the housing, the retention device including a mounting member and a tab, removably carrying the leverage arm on the retention device, mounting a cover on the housing, the cover being movable between a closed position and an open position, and resisting removal of the leverage arm from the retention device with the cover in the closed position.
These and other aspect and advantages of the present invention will be more readily understood from the following description.
REFERENCES:
patent: 5495388 (1996-02-01), Bonetti et al.
patent: 5577603 (1996-11-01), Bogdanovs et al.
patent: 5663862 (1997-09-01), Hopping-Mills
patent: 5911316 (1999-06-01), Chu
patent: 5973278 (1999-10-01), Wehrli, III et al.
patent: 6087602 (2000-07-01), Bernier et al.
Cutler-Hammer, Eaton,Cutler-Hammer Commercial Metering Switchboards, File No. 31-500, pp. 1-4, (May 1997).
Friedhofer Michael
Moran Martin J.
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