Patent Application
20050279734
1. Field of the Invention
This invention relates to electrical switching apparatus, such as, for example, a circuit breaker, having an arc runner, which transfers an arc from separable contacts to an arc chute where the arc is extinguished. The invention also relates to arc runner assemblies.
2. Background Information
Electrical switching apparatus for power distribution systems include devices such as, for instance, circuit breakers, network protectors, transfer switches and disconnect switches. Power circuit breakers, for example, are typically used to connect a power distribution network to a power source. Such power circuit breakers withstand high currents for a period of time, without tripping, in order to give other circuit breakers in the network time to respond and isolate the fault, thereby localizing disruption of service. Thus, by the time the power circuit breaker responds, it may have to interrupt a sizable current. This results in the drawing of an arc as the circuit breaker contacts open.
It is known to provide an arc chute adjacent to the opening path of the circuit breaker contacts. The arc chute is constructed of a number of spaced apart plates extending transverse to the arc. As the contacts open, the arc is transferred by electromagnetic forces to the arc plates, which cool the arc and increase the arc voltage by breaking it up into sections, both of which help to extinguish the arc.
It is known to employ an arc runner to drive an arc from a stationary contact to an arc chamber. See, for example, U.S. Pat. Nos. 4,229,630; 5,969,314; 6,417,474; and 6,452,470.
U.S. Pat. No. 5,969,314 discloses that a longitudinal vertical slot is disposed into the center of an arc runner in order to provide an attractive edge for the arc to travel toward the center of an arc chute. The edge of the slot encourages the arc to travel up the center of the arc runner, engaging the arc chute near the center and extinguishing the arc sooner.
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There is a need, therefore, for electrical switching apparatus with an improved arrangement for extinguishing arcs generated during current interruption.
There is a more specific need for such an improved arrangement for directing the arc from a stationary contact into an arc chute.
Accordingly, there is room for improvement in circuit breakers including arc runners.
These needs and others are met by the present invention, which provides an arc runner clinch assembly that employs a clinch joint, as contrasted with a screw, in order to provide a relatively smooth surface to direct an arc from a stationary contact to arc plates of an arc chute.
In accordance with one aspect of the invention, an arc runner clinch assembly comprises: a conductor; a fixed contact connected to the conductor; and an arc runner disposed on the conductor adjacent the fixed contact, the arc runner including a first portion abutting the fixed contact, a second portion adapted to draw an arc from the fixed contact and two legs clinching the conductor.
Each of such legs of the arc runner may include a foot, which is bent to clinch the conductor. The first and second portions of the arc runner may form a longitudinal segment disposed away from the fixed contact.
As another aspect of the invention, an electrical switching apparatus comprises: a conductor; a fixed contact connected to the conductor; an arc runner disposed on the conductor adjacent the fixed contact, the arc runner including a first portion engaging the fixed contact, a second portion adapted to draw an arc from the fixed contact and two legs clinching the conductor; a movable contact; an operating mechanism cooperating with the movable contact for opening and closing the fixed and movable contacts; and an arc chute adjacent the second portion of the arc runner.
The arc runner may have a generally L-shaped profile formed by a longitudinal segment and the legs of the arc runner. The longitudinal segment and the legs of the arc runner may form an opening, which receives the conductor.
As another aspect of the invention, a circuit breaker comprises: a conductor; a fixed contact connected to the conductor; an arc runner disposed on the conductor adjacent the fixed contact, the arc runner including a first portion abutting the fixed contact, a second portion adapted to draw an arc from the fixed contact and means for clinching the conductor; a movable contact; an operating mechanism cooperating with the movable contact for opening and closing the fixed and movable contacts; an arc chute adjacent the second portion of the arc runner; and a trip unit cooperating with the operating mechanism to trip open the fixed and movable contacts.
A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:
As employed herein, the statement that two or more parts are “connected” or “coupled” together shall mean that the parts are joined together either directly or joined through one or more intermediate parts. Further, as employed herein, the statement that two or more parts are “attached” shall mean that the parts are joined together directly.
As employed herein, the term “fastener” shall expressly include, but not be limited to, any suitable fastening member(s) (e.g., without limitation, a threaded fastener; a non-threaded fastener; a removable fastener; a non-removable fastener; a bolt; a machine screw; a rivet; a soldered connection; an adhesive connection), which is employed such that two or more parts are connected or coupled together.
The invention is applicable to electrical switching apparatus such as, for example, circuit breakers, network protectors, transfer switches and disconnect switches having separable contacts, and will be described as applied to a power circuit breaker having separable contacts. An example of a circuit breaker is disclosed in U.S. Pat. No. 6,452,470, which is incorporated by reference herein.
Referring to
As is conventional, the circuit breaker 20 includes a movable contact 34, an operating mechanism 36 cooperating with the movable contact 34 for opening and closing the fixed and movable contacts 24,34, and an arc chute 38 adjacent the arc runner second portion 30.
The arc extinguisher assembly 58 includes an arc chute 74 within which are positioned spaced-apart generally parallel angularly offset arc chute plates 76. The arc extinguisher assembly 58 receives and dissipates electrical arcs that are created upon separation of the contacts 66,68 of the circuit breaker 40.
As shown in
Referring to
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The disclosed arc runner clinch assembly 88 prevents an arc from stalling on the arc runner 26 by employing a relatively smooth longitudinal segment 33. This assembly 88 also provides a material cost reduction and reduces assembly time, since a screw or other separate fastener is eliminated.
While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.
