Patent Application
20080289938
This invention is directed generally to an electrical circuit breaker, and, more particularly, to a plug-on half jaw and symmetrical jaw spring for a circuit breaker.
Circuit breakers are well known in the art, and are designed to trip in response to an electrical interruption event caused by an overload, short circuit, or thermal runaway condition, thereby opening the circuit to which the circuit breaker is connected and reducing the possibility of damage to the conductor wires or the loads connected to the circuit breaker. A circuit breaker can be reset (either manually or automatically) to resume power flow to the loads.
Some circuit breakers contain a plug-on full jaw, which is made of copper, that is coupled with a jaw spring for mechanically securing a bus bar to the circuit breaker. The full jaw also electrically couples the bus bar to a stationary contact of the circuit breaker. One problem associated with the full jaw is that its inherent design of having two terminal ends considerably increases the material cost.
What is needed, therefore, is a circuit breaker having a plug-on device that reduces material cost.
In one implementation, a circuit breaker includes a stationary contact, a plug-on half jaw, and a jaw spring. The plug-on half jaw is electrically coupled to the stationary contact and has a single terminal end for receiving a bus bar. The jaw spring is operatively coupled to the half jaw and has a bridge portion connecting two symmetrical spring legs.
In an alternative implementation, a method of assembly for a circuit breaker includes electrically coupling a plug-on half jaw to a stationary contact, the half jaw having a single terminal end for receiving a bus bar. The half jaw is mounted in a circuit breaker base. A jaw spring is inserted into the circuit breaker base for operatively coupling the jaw spring to the half jaw. The jaw spring has two symmetrical spring legs, one of the spring legs mechanically cooperating with the single terminal end of the half jaw to apply sliding contact pressure when receiving the bus bar.
In another alternative implementation, a circuit breaker assembly includes a base for receiving internal components of a circuit breaker and a cover for at least partially enclosing the internal components. A half jaw is mounted to the base and has a stationary contact. The half jaw is in electrical contact with the stationary contact and has a single terminal end for electrically contacting a bus bar. A jaw spring is mounted to the base and is operatively coupled to the half jaw. Further, the jaw spring has two symmetrical legs, one of the legs forming a terminal receiving gap with the terminal end for receiving the bus bar.
Additional aspects of the invention will be apparent to those of ordinary skill in the art in view of the detailed description of various implementations, which is made with reference to the drawings, a brief description of which is provided below.
The invention may best be understood by reference to the following description taken in conjunction with the accompanying drawings, in which:
Although the invention will be described in connection with certain preferred embodiments, it will be understood that the invention is not limited to those particular embodiments. On the contrary, the invention is intended to include all alternatives, modifications and equivalent arrangements as may be included within the spirit and scope of the invention as defined by the appended claims.
Turning now to
The circuit breaker 100 has several positions, including an ON position, a TRIPPED position, and an OFF position. When the circuit breaker 100 is in the ON position, current flows unrestricted through the circuit breaker 100 and, therefore, through the electrical device or circuit that the circuit breaker is designed to protect. In the ON position, the movable contact 102 is in direct contact with the stationary contact 104.
When the circuit breaker 100 is in the TRIPPED position, current flow through the circuit breaker 100 is interrupted and, consequently, current does not flow through the electrical device or circuit that the circuit breaker is designed to protect. The TRIPPED position is caused by the presence of a current higher than the rated current for the circuit breaker 100 over a specified period of time. When the circuit breaker 100 is in the OFF position, current flow is generally manually interrupted from flowing through the circuit breaker 100. In the TRIPPED and OFF positions the movable contact 102 is separated from the stationary contact 104.
The movable contact 102 is operatively coupled to a trip unit and a switching mechanism (not shown) to interrupt electrical contact when a trip condition occurs. The exposure of the circuit breaker 100 over the specified period of time to a current that exceeds the rated current by a predetermined threshold activates a tripping mechanism. Activation of the tripping mechanism causes the switching mechanism to interrupt current flow through the circuit breaker 100 by separating the movable contact 102 from the stationary contact 104. In
The stationary contact 104 is mechanically and electrically coupled to the half jaw 106. Specifically, the stationary contact 104 is a small circular cylinder that is mechanically secured directly to the half jaw 106. The half jaw 106 is inserted into a respective mounting location on the base 100, and the jaw spring 108 is inserted in a partially overlapping position relative to the half jaw 106.
The half jaw 306 inherently provides a reduction in necessary material because it has only one (i.e., a single) terminal end 320. Thus, in contrast to a full jaw (which has two terminal ends), the half jaw 306 considerably reduces the associated material cost.
The single terminal end 320 has an end portion 324 proximate the internal surface 322. The end portion 324 is angled in a direction away from the bus bar, to reduce the possibility of mechanical interference when inserting the bus bar.
The half jaw 306 also has a contact end 326 on which the stationary contact 304 is mechanically and electrically secured. The contact end 326 is connected to the single terminal end 320 via a connecting surface 328, which is generally angled downwards from a top end of the contact end 326. The contact end 326 is positioned generally perpendicular to the single terminal end 320.
After the half jaw 406 is mounted to the base 401, the jaw spring 408 is inserted along an X-axis direction into its respective position on the circuit breaker base 401. Specifically, an internal surface of one of its two spring legs 412, 414 is positioned in direct contact with an internal surface 422 of the half jaw 406. Thus, the jaw spring 408 partially overlaps the half jaw 406 when mounted in its respective position on the circuit breaker base 401. Because the jaw spring 408 is symmetrical, the orientation of its spring legs 412, 414 about the Y-axis direction is irrelevant. In other words, it is irrelevant whether a first spring leg 412 is up (away from the base 400 along the Z-axis direction) or down (towards the base 400 along the Z-axis direction). Thus, the symmetrical aspect of the jaw spring 408 reduces, or even eliminates, the need to include automated and/or manual assembly rejection features associated with the detection and removal of improperly assembled circuit breakers.
While particular embodiments, aspects, and applications of the present invention have been illustrated and described, it is to be understood that the invention is not limited to the precise construction and compositions disclosed herein and that various modifications, changes, and variations may be apparent from the foregoing descriptions without departing from the spirit and scope of the invention as defined in the appended claims.
