Electricity: circuit makers and breakers – Electric switch details – Contact
Reexamination Certificate
2001-09-21
2003-04-08
Enad, Elvin (Department: 2832)
Electricity: circuit makers and breakers
Electric switch details
Contact
Reexamination Certificate
active
06545237
ABSTRACT:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
The present U.S. patent application having at least one common inventor as:
U.S. patent application Ser. No. 10/252,633 entitled “System and Method for Auxiliary Contact Assembly”, and
U.S. patent application Ser. No. 09/961,159 entitled “System and Method for Auxiliary Contact Assembly and Snap Mounting”, and
U.S. patent application Ser. No. 09/961,162 entitled “System and Method for Mounting a Pusher and Moveable Contact in a Contact Block”, and
U.S. patent application Ser. No. 09/961,158 entitled “Contact Block Assembly and Method of Assembling a Contact Block Assembly”, and
U.S. patent application Ser. No. 09/961,161 entitled “Pusher Assembly and Method for Assembling a Pusher Assembly”,
U.S. patent application Ser. No. 09/961,160 entitled “Movable Contact and a Method of Assembling a Pusher Assembly having a Movable Contact”,
are filed with the U.S. patent and Trademark Office concurrently on Sep. 21, 2001, the entirety of each being incorporated herein by reference.
TECHNICAL FIELD OF THE INVENTION
This invention relates to a contact assembly for use in an electrical switching apparatus designed to facilitate mounting of a moveable contact.
BACKGROUND OF THE INVENTION
A conventional electrical switching apparatus in one known form typically comprises an electromagnetically actuable device having a magnetic core proximate an armature. Typically, a coil is electrically energized to draw the armature to the magnetic core. The electromagnetically actuated device may be a control relay, a contactor, a motor starter or the like. The armature is operatively associated with a movable device such as an actuator. With an electrical switching apparatus the actuator operates a contact assembly.
A contact assembly may be an integral component of the electrical switching apparatus or it may an auxiliary device to be added thereto. In either case, a housing typically supports an electrical contact and a pusher. The pusher is selectively actuated to operate the electrical contact. A typical electrical contact includes one or two stationary contacts mounted in the housing and a moveable contact mounted on the pusher. The stationary contact and the moveable contact each typically include a metal bar carrying a contact pad on one side. The electrical contact is made when the contact pad of the moveable contact makes contact with the contact pad of the stationary contact. The electrical contact is broken when the contact pad of the moveable contact is spaced from the contact pad of the stationary contact.
A problem in manufacturing is that moveable contacts are mistakenly mounted in an inverted position on the pusher. When mounted in an inverted position the movable contact metal bar may make contact with the contact pad of the stationary contact to complete the circuit. However, due to the incorrect assembly, the useful life of the contact assembly is greatly reduced.
Unfortunately, a typical continuity test, in which the pusher is driven against its own internal stops, does not reveal if the moveable contact is mounted in an inverted position on the pusher.
Accordingly, there is a need for a contact assembly for use in an electrical switching apparatus designed to eliminate opportunity of incorrect assembly.
SUMMARY OF THE INVENTION
In accordance with the invention there is provided a contact assembly for use in an electrical switching apparatus designed to eliminate opportunity of incorrect assembly.
In accordance with one aspect of the invention there is disclosed a contact assembly for use in an electrical apparatus. An armature comprises a base and a post having first and second ends. The first end is connected to the base and the second end comprises intersecting cross members defining four quadrants and a body extending between the cross members in one of the four quadrants. A moveable contact is received on the post. The moveable contact comprises an elongate bar having contact pads at opposite ends of one face and a central opening. The central opening comprises intersecting slots defining four quadrants and a void extending between the slots in one of the four quadrants. The central opening is slightly larger than the post second end so that the moveable contact is mounted to the post with the contact pads facing in a desired direction.
It is a feature of the invention that one of the slots has a greater length than the other of the slots and one of the cross members has a greater length than the other of the cross members. The slot having the greater length extends longitudinally and the other of the slots extends transversely.
It is another feature of the invention that the base comprises an elongate base and in one aspect of the invention the cross member having the greater length extends longitudinally relative to the elongate base. The post includes a support below the second end to support the moveable contact longitudinally extending relative to the elongate base.
In another aspect of the invention the cross member having the greater length extends transversely relative to the elongate base. The post has a narrower section between the first and second ends and the moveable contact is mounted on the narrower section and extends longitudinally relative to the elongate base and the cross member having the greater length acts as a fulcrum for the moveable contact.
In accordance with yet another aspect of the invention there is disclosed a contact assembly for use in an electrical apparatus. An armature comprises a base and a post having first and second ends. The first end is connected to the base and the second end has an asymmetric head. A moveable contact is received on the post. The moveable contact comprises an elongate bar having contact pads at opposite ends of one face and a central opening. The central opening is asymmetric, similar in shape to the asymmetric head. The central opening is slightly larger than the asymmetric body so that the moveable contact is mounted to the post with the contact pads facing in a desired direction.
There is disclosed in accordance with a further aspect of the invention the method of mounting a moveable contact in a contact block comprising: providing an armature comprising a base, a post having first and second ends, the first end being connected to the base and the second end comprising intersecting cross members defining four quadrants and a body extending between the cross members in one of the four quadrants; mounting a moveable contact on the post, the moveable contact comprising an elongate bar having contact pads at opposite ends of one face and a central opening, the central opening comprising intersecting slots defining four quadrants and a void extending between the slots in one of the four quadrants, the central opening being slightly larger than the post second end so that the moveable contact is mounted to the post with the contact pads facing in a desired direction; and mounting the armature in a housing.
Further features and advantages of the invention will be readily apparent from the specification and from the drawings.
REFERENCES:
patent: 6180899 (2001-01-01), Passow
Passow Christian H.
Tews Kevin B.
Enad Elvin
Fishman M.
Siemens Energy & Automation
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