Electricity: circuit makers and breakers – Interlocking – Drawout-type switchgear
Reexamination Certificate
1999-11-05
2001-07-24
Friedhofer, Michael (Department: 2832)
Electricity: circuit makers and breakers
Interlocking
Drawout-type switchgear
C361S608000
Reexamination Certificate
active
06265678
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a circuit breaker draw-withdraw apparatus for use with a circuit breaker to move the circuit breaker so as to be connected to or be disconnected from a plug-in base.
Conventionally, a plug-in base for a circuit breaker is mounted on a panel board or other base structure and is wired to circuitry on the base structure. A circuit breaker is installed in the plug-in base by inserting stabs protruding from the circuit breaker into jaws fixed to the plug-in base. The jaw/stab connection provides the primary electrical connection between the circuit breaker and the plug-in base. This connection may also mechanically retain the circuit breaker in the plug-in base.
Withdraw mechanisms have been developed for mechanically drawing a circuit breaker unit into a plug-in base and withdrawing the circuit breaker unit from the plug-in base. An example of such a withdraw mechanism is disclosed in U.S. Pat. No. 5,837,949 to Green et al. The withdraw mechanism described in Green et al. is operated by rotating a screw linkage using a drive tool inserted into the front of the withdraw mechanism which draws the circuit breaker into or withdraws the circuit breaker from the plug-in base. This type of mechanism is advantageous since a high amperage circuit breaker is heavy and thus difficult for a technician to position properly in the plug-in base by hand. In addition, the jaws in a high amp plug-in base may require a high insertion force, making it difficult or impossible for a technician to apply sufficient force to fully insert the stabs into the jaws.
A circuit breaker withdraw mechanism typically includes a component attached to the plug-in base and a component attached to the circuit breaker. Installation of the withdraw mechanism may take place in the field, in a supplier warehouse or at the circuit breaker production plant.
It is desirable to ensure that the screw linkage of the withdraw mechanism ceases operation after the drive tool rotates the screw linkage past its operational range of motion, both in the withdraw and install directions. In lower amperage applications, this may be accomplished by providing stops at either end of the screw linkage travel, preventing rotation of the screw linkage past the operational range of motion. However, in high-amperage applications stops are not adequate since greater torque must be applied to the drive tool and the mechanism may be damaged by over-travel. Accordingly, there is a need to provide improved over-travel protection in a withdraw mechanism.
SUMMARY OF THE INVENTION
An object of the invention is to fulfill the need referred to above. In accordance with the principles of the present invention, this objective is achieved by providing a mechanism for moving a circuit breaker with respect to a circuit breaker connecting apparatus so as to connect or disconnect the circuit breaker from the circuit breaker connecting apparatus. The mechanism comprises a draw bracket assembly including a draw bracket constructed and arranged to be mounted to the circuit breaker connecting apparatus so as to be generally adjacent to a side of the circuit breaker connecting apparatus. A guide engaging member is mounted for generally vertical movement with respect to the draw bracket. The guide engaging member has a slot structure therein having surfaces constructed and arranged to receive and engage a guide associated with the circuit breaker for moving the circuit breaker with respect to the circuit breaker connecting apparatus. A drive member is provided and has a movable element. The drive member is constructed and arranged to be actuated so as to cause movement of the movable element. A motion transmitting structure is operatively associated with the movable member and the guide engaging member such that movement of the movable element causes the motion transmitting structure to move thereby causing the guide engaging member to move between an operational range of motion to engage or disengage the circuit breaker from the circuit breaker connecting apparatus. The movable element is constructed and arranged to disengage from the drive member or disengage from the motion transmitting structure outside of the operational range of motion.
In accordance with another aspect of the invention, a method of preventing over-travel of a circuit breaker movement structure is provided. The movement structure includes a circuit breaker assembly having a guide, a circuit breaker connecting apparatus having a draw bracket with a guide engaging member being mounted for generally vertical movement with respect to the draw bracket, the guide engaging member having a slot structure therein, a drive member having a movable element, the drive member being constructed and arranged to be actuated so as to cause movement of the movable element, and a motion transmitting structure operatively associated with the movable member and the guide engaging member. The method includes actuating the drive member to move the movable element causing the motion transmitting structure to move thereby causing the guide engaging member to move between an operational range of motion to engage or disengage the circuit breaker from the circuit breaker connecting apparatus by use of the guide. The movable element is caused to disengage from the drive member or from the motion transmitting structure outside of the operational range of motion.
Other objects, features and characteristics of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification.
REFERENCES:
patent: 4914549 (1990-04-01), Leone et al.
patent: 5278722 (1994-01-01), Peruso
patent: 5337210 (1994-08-01), Ishikawa et al.
patent: 5837949 (1998-11-01), Green et al.
patent: 5912444 (1999-06-01), Godesa
patent: 6028272 (2000-02-01), Akers
patent: 6031192 (2000-02-01), Liebetruth
Blessitt James H.
Robbins W. Dale
Friedhofer Michael
Siemens Energy & Automation Inc.
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