Circuit breaker with arc shield

Abstract

A circuit interrupter having a first contact positioned on a moveable contact arm that is moveable into and out of physical contact with a stationary contact. An arc horn shield positioned on or affixed to an escapement that is coupled to the moveable contact arm, the arc horn shield including a substantially U-shaped tab that is provided as a protrusion with an arc receiving surface such that when the moveable contact is moved into the vicinity of the protrusion, any arc that may be formed between the contacts is passed from the moveable contact to the arc receiving surface to minimize damage to the moveable contact and extinguish the arc.

Claims

1. A circuit interrupter comprising: a set of contacts including a stationary contact and a moveable contact; a contact arm having a first end and a second end, said moveable contact positioned at the first end; a linkage coupled to the second end of said contact arm, said linkage coupled to an overcurrent measurement device and to a handle; an escapement coupled at a first end to said contact arm at a location between the first and second ends of said contact arm, said escapement coupled at a second end to the handle, wherein actuation of the handle causes said moveable contact arm to move to either open or close said set of contacts; and an arc horn shield mounted onto said escapement, said arc horn shield including a protrusion extending from a side portion thereof defined by a tab that includes an arc receiving surface such that when the moveable contact arm is displaced to an open position, said moveable contact is moved into a vicinity of the arc receiving surface.

2. The circuit interrupter of claim 1, wherein said arc horn shield is formed as an elongated device comprising a first side, a second side and a third side, said protrusion extending from said second side and said first and third sides are substantially parallel with respect to each other.

3. The circuit interrupter of claim 2, wherein said tab is formed as a substantially U-shaped tab.

4. The circuit interrupter of claim 3, wherein when the moveable contact arm is moved to an open position, the first end of the contact arm passes below a curved portion of the substantially U-shaped tab.

5. The circuit interrupter of claim 3, wherein when the moveable contact arm is moved to an open position, during an opening process, the arc receiving surface become substantially parallel with the moveable contact arm when the first end of the moveable contact arm comes into the vicinity of the arc receiving surface.

6. The circuit interrupter of claim 5, wherein when the moveable contact arm is moved to the open position, the first end of the moveable contact arm advances beyond the arc receiving surface when the moveable contact arm reaches a fully open position.

7. The circuit interrupter of claim 2, wherein said arc horn shield is mounted on said escapement such that a portion of the escapement in the vicinity of the first end of said moveable contact arm when the contact arm is moved to the open position is substantially enclosed within said arc horn shield.

8. The circuit interrupter of claim 2, wherein the first and third sides are substantially L-shaped.

9. The circuit interrupter of claim 1, wherein said arc horn shield comprises a metal material or an alloy material.

10. A circuit interrupter comprising: a first stationary contact; a second moveable contact; a contact arm having a first end and a second end, said moveable contact positioned toward the first end; a handle; an escapement coupled at one end to a point along a length of said contact arm and at another end to said handle, wherein actuation of said handle causes said moveable contact arm to move said moveable contact into and out of physical contact with said stationary contact; and an arc horn shield mounted onto said escapement, said arc horn shield including a protrusion extending from a side portion thereof defined by a tab that includes an arc receiving surface such that when the moveable contact arm is displaced to an open position, said moveable contact is moved into a vicinity of the arc receiving surface.

11. The circuit interrupter of claim 10, wherein said arc horn shield is formed as an elongated device comprising a first side, a second side and a third side, said protrusion extending from said second side and said first and third sides are substantially parallel with respect to each other.

12. The circuit interrupter of claim 11, wherein said tab is formed as a substantially U-shaped tab.

13. The circuit interrupter of claim 12, wherein when the moveable contact arm is moved to an open position, the first end of the contact arm passes below a curved portion of the substantially U-shaped tab.

14. The circuit interrupter of claim 12, wherein when the moveable contact arm is moved to an open position, during an opening process, the arc receiving surface become substantially parallel with the moveable contact arm when the first end of the moveable contact arm comes into the vicinity of the arc receiving surface.

15. The circuit interrupter of claim 14, wherein when the moveable contact arm is moved to the open position, the first end of the moveable contact arm advances beyond the arc receiving surface when the moveable contact arm reaches a fully open position.

16. The circuit interrupter of claim 11, wherein said arc horn shield is mounted on said escapement such that a portion of the escapement in the vicinity of the first end of said moveable contact arm when the contact arm is moved to the open position is substantially enclosed within said arc horn shield.

17. The circuit interrupter of claim 11, wherein the first and third sides are substantially L-shaped.

18. The circuit interrupter of claim 11, further comprising a linkage coupled to the second end of said contact arm, said linkage coupled to an overcurrent measurement device and to the handle, wherein said overcurrent measurement device functions to actuate said moveable contact arm to an open position when an overcurrent condition is detected.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an illustration of a configuration for the circuit interrupter according to the invention.

(2) FIG. 2 is an illustration of the arc horn shield according to FIG. 1.

(3) FIG. 3 is an illustration of the moveable contact arm opening the contacts with an arc shown between the contacts according to FIG. 1.

(4) FIG. 4 is an illustration of the moveable contact arm opening the contacts with an arc shown between the stationary contact and the arc horn according to FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

(5) Referring now to the drawings, wherein like reference numerals designate corresponding structure throughout the views.

(6) FIG. 1 illustrates components of an example circuit interrupter 100 according to aspects of the invention.

(7) Circuit interrupter 100 may be any device which can be used to make and break a circuit using contacts. For example, it will be clear to those having ordinary skill in the art that circuit interrupter 100 may be a simple switch, or may be implemented as a circuit breaker having a housing 102, for example. Housing 102 may include vents to allow gasses and debris produced by arcing to escape housing 102.

(8) Circuit interrupter 100 includes a stationary contact 110 that is electrically connected to line terminal 120 through conductor 122. The line terminal receives electricity from a power source, such as, a generator (not shown), which in some applications is supplied by a power company.

(9) Circuit interrupter 100 still further includes a moveable contact 112 mounted on moveable contact arm 130. The moveable contact 112 is positioned toward a first end 132 of the moveable contact arm 130. The moveable contact arm 130 further includes a second end 134 that is opposite the first end 132.

(10) Moveable contact arm 130 is, in turn, connected to escapement 140, which includes a first end 142 and a second end 144. The first end 142 of escapement 140 is connected to the moveable contact arm at a location along a length of the moveable contact arm and preferably toward a mid-point 136 thereof.

(11) The second end 144 of escapement 140 is connected to a handle 150 that extends from housing 102.

(12) First movable contact 112 is connected to load terminal 124 through a conductor 126 to overcurrent measurement device 160 and through conductor 128. The overcurrent measurement device 160 may be any type of well-known device for measuring current that passes through the circuit interrupter 100. Once a maximum current is reach, the measurement device will function to cause the contact arm 130 to move to an open position. Likewise, the handle 150 will move to an intermediate position to indicate a tripped state of circuit interrupter 100.

(13) Also illustrated in FIG. 1 is arc horn shield 170, which is mounted to or on escapement 140. Arc horn shield 170 may comprise any conductive material including, but not limited to, a metal or alloy material.

(14) The arc horn shield will now be discussed in connection with FIGS. 1 and 2. Arc horn shield 170 is provided as an elongated device that includes a first side 172, a second side 174 and a third side 176. The second side 174 includes a protrusion 178 that is formed as a substantially U-shaped tab. The substantially U-shaped tab has a curved portion 180 that corresponds with the bottom of the U, and an arc receiving surface 182 that comprises a substantially flat surface.

(15) As can be seen with reference to FIG. 1, arc horn shield 170 is mounted to escapement 140 and substantially surrounds three sides of escapement 140. Mounting holes 184 are provided on the first side 172 and the third side 176 for affixing arc horn shield 170 to escapement 140.

(16) Turning also now to FIGS. 3 and 4, it can be seen that first side 172 (and corresponding third side 176) are provided as substantially L-shaped (upside down L in FIG. 3) with the protrusion 178 extending from the second side 174. The protrusion 178 is formed as a tab that is bent backward upon itself.

(17) The function and operation of the circuit interrupter 100 including the arc horn shield 170 will now be discussed.

(18) In FIG. 3, the opening of the moveable contact arm 130 is illustrated. When moveable contact 112 is moved away from stationary contact 110 and current if flowing between the set of contacts, the current will continue to flow as the contacts move from a closed position to an open position. The result of this current flowing through the gap that forms between the set of contacts forms an arc 190.

(19) The moveable contact arm is rotated upward such that moveable contact 112 is moved away from stationary contact 110. In FIG. 4 it can be seen that the first end 132 of moveable contact arm 130 moves toward protrusion 178, the arc 190 is passed from moveable contact 112 to arc receiving surface 182 of protrusion 178. As seen in FIG. 3, the moveable contact arm comes substantially parallel with arc receiving surface 182 as the first end 132 of moveable contact arm 130 comes into the vicinity of the protrusion 178.

(20) In FIG. 4 it can be seen that the first end 132 of moveable contact arm 130 passed by or under curved portion 180. As stated previously, arc horn shield 170 is mounted to escapement 140 and substantially surrounds three sides of escapement 140. The positioning of the arc horn shield 170 is provided to protect escapement. As the moveable contact 112 moves toward and into the vicinity of the escapement 140, the arc 190, which causes a relatively large amount of heat to be generated, debris may be melted off of the contacts and migrate or be flung into the mechanism, and in particular, escapement 140, can destroy or seriously damage escapement 140. Accordingly, arc horn shield 170 provides protection physical protection to escapement 140 either directly from arc 190 or from debris that may be flung from the heating that occurs due to the arcing.

(21) Although the invention has been described with reference to a particular arrangement of parts, features and the like, these are not intended to exhaust all possible arrangements or features, and indeed many other modifications and variations will be ascertainable to those of skill in the art.