BLASTING TERMINAL FOR A CIRCUIT CIRCUIT BREAKER
Field of the Invention The present invention relates generally to circuit breakers and, more particularly to an improved blasting terminal for a circuit breaker. BACKGROUND OF THE INVENTION The use of circuit breakers is widespread in current residential, commercial and industrial electrical systems, and is an indispensable component of such systems to provide protection against over-current conditions. The various circuit breaker mechanisms have evolved and been refined over time based on specific application factors such as current capacity, response time, and the type of reset function (manual or remote) desired from the circuit breaker. A circuit breaker employs a pair of mating contacts that establish a current path between them during normal operation of the circuit in which the circuit breaker is installed. However, in response to a high current condition in the circuit, the mating contacts are separated from each other to interrupt the current path between them. One of the contacts is a movable contact connected to the end of an elongated blade, capable of rotating, while the other of the contacts is a stationary contact attached to a fixed blasting terminal. In response to the high current condition, the blast terminal provides an electromagnetic repulsion towards the blade capable of rotating. In a type of blasting terminal, shown in Figure 1, a blasting terminal 10 is configured in the shape of a U-shaped turn. The flow of current in the blasting terminal 10 is sketched by the arrows in the figure 1. It can be seen that the current flow reverses the directions from the input section 12 to the output section 14 of the terminal 10. This current reversal causes an electromagnetic repulsion between the input and output sections 12, 14. During normal operation of the circuit, the current flow from the outlet section 14 passes through the stationary contact 16 to a movable mating contact (not shown) of a blade capable of rotating. During a current condition
"High", the terminal 10 repels the blade capable of rotating to separate the movable contact from the stationary contact 16. This separation is accelerated by the U-shaped configuration of the blasting terminal 10. A disadvantage of the blasting terminal 10 is that is not favorable for manufacturing. In a manufacturing technique, the terminal 10 is manufactured by imparting successive bends perpendicular to the developed length of the metallic raw material used for its manufacture. In Figure 1, these folds are designated by the reference numbers 18 and 20. Although this process saves the use of materials, the formation process becomes more difficult with each subsequent fold. The manufacturer must accommodate brazing operations by either partially forming the terminal with the bend 18, and then proceeding with the brazing of the contact 16 to the outlet section 14 or at least providing some type of clearance holes so that the contact 16 can subsequently be attached to the outlet section 14. Terminal 10 must then have a final forming operation where it is imparted with bend 20. This final forming operation is difficult to carry out because the contact 16 already is in place and because the terminal material has been tempered partially from the brazing operation. In another manufacturing technique, the terminal 10 is formed from two or more separate pieces that are mechanically fastened or welded together. The disadvantages of this technique are that it is intensive in parts and can be a source of high strength within the assembled terminal. In consecuense, there is a need for a blasting terminal that can be implemented without the aforementioned disadvantages. SUMMARY OF THE INVENTION The present invention provides a blasting terminal that is cost effective and easy to manufacture. The present invention further provides a blast terminal that is configured to reverse the direction of current flow as the current passes from the input section to the output section of the terminal. In one implementation of the present invention, a blasting terminal includes a flat conductive tip, a flat, conductive inlet section, and a flat, conductive output section. The entrance section includes a pair of generally parallel U-shaped strips. Each of the pair of strips includes first and second end portions and a central portion bridging the first and second end sections. The first and second end portions and the central portion of each of the pair of strips are generally co-planar. The tip and the outlet section are substantially parallel to each other. The outlet section is elongated and includes first and second ends, the first end being disposed closer to the tip than the second end. The first end portions of the strips are connected perpendicular to the opposite sides of the tip, and the second end portions are connected perpendicular to the opposite sides of the second end of the outlet section. A stationary contact is connected to the surface of the outlet section. The above summary of the present invention is not intended to represent each embodiment or each aspect of the present invention. This is the purpose of the drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the invention will become apparent upon reading the following detailed description and with reference to the drawings, in which: Figure 1 is a perspective view of a type of blasting terminal of the prior art.; Figure 2 is a perspective view of a blasting terminal embodying the present invention; and Figure 3 is a top view of the blasting terminal of Figure 2, before imparting four bends in the manufacturing process. Although the invention is susceptible to various modifications and alternative forms, its specific embodiments have been shown by way of example in the drawings and will be described in detail. However, it should be understood that this is not intended to limit the invention to the particular form described. On the contrary, the intention is to cover all modifications, equivalents and alternatives that fall within the spirit and scope of the invention, as defined by the appended claims. Detailed Description of the Preferred Embodiment Turning now to the drawings, Figure 2 illustrates a blasting terminal 30 including a flat conductive tip 32, a conductive inlet section 34, and an outlet section
* conductive, flat 36. The tip 32 is provided with an opening 38 for mounting the terminal 30 within a circuit breaker housing. The entry section 34 includes a pair of parallel U-shaped strips, each of which includes a first end 40, a second end 42, and a central portion 44 that bridges the first and second ends 40, 42. In each of the strips of the pair of U-shaped strips, the first end 40, the second end 42 and the central portion 44 are co-planar, and the first and second ends 40, 42 are perpendicular to the central portion 44. Both the tip 32 and the outlet section 36 are co-planar, rectangular in shape, and elongated in the current flow direction such that the longitudinal axis of symmetry of the tip is co-linear with the longitudinal axis of the symmetry of the tip. exit section 36. Further, the tip 32 and the exit section 36 are positioned midway between the and two U-shaped strips of the entry section 34 such that the U-shaped strips are arranged symmetrically around point 32 and section d and outlet 36. The first end portions 40 of the respective U-shaped strips are formed integrally with the opposite longitudinal sides of the tip 32 at one end 50. Similarly, the second end portions 42 of the respective strips in U-shape are formed integrally with the opposite longitudinal sides of the section? outlet 36 at one end 52. Tip 32 extends from its end 50 in a direction away from inlet section 34 so that the current passing through tip 32 and entering inlet section 34 does not reverse your adress. In contrast, the outlet section 36 extends from its end 52 in a direction toward the tip 32 so that the current that passes through the inlet section 34 and enters the outlet section 36 reverses its direction. The current path through the blasting terminal 30 will now be described in greater detail. The current of the circuit in which the terminal 30 is installed flows first towards the tip 32. Next, if the terminal 30 has a perfectly symmetrical design, the current is divided into two parts, one half of the current flowing through one. of the U-shaped strips of the inlet section 34 and the other half flowing through the other of the U-shaped strips, the two halves coming back together as they flow into the section of
W output 36. During normal operation of the circuit, current flows through the outlet section 36 and through a stationary contact 54 to a movable mating contact (not shown) of a rotating blade (not shown). Such a rotating blade is described in the United States patent application Serial No. (CRC-35 / SQUC132), entitled "Blade Suspension Assembly for a Circuit Breaker", filed simultaneously with this, assigned to it. Assignee, and incorporated herein by reference. The stationary contact 54 is mounted on the surface of the outlet section 36 in a position slightly off center by joining means such as welding. It can be seen that the geometry of the blasting terminal 30 is configured to reverse the direction of current flow in the portion of the terminal closest to the blade capable of rotating. As indicated by the arrows in Figure 2, the current flow reverses in direction as it passes from $ "" the input section 34 to the output section 36. This current reversal causes an electromagnetic repulsion between the input section 34 and the output section 36. During a high current condition, this electromagnetic repulsion accelerates the rotation of the blade so as to improve the interruption performance of the circuit. The blasting terminal 30 is manufactured by first stamping a sheet of metallic raw material in the shape sketched in Figure 3. At this point, the tip 32, the exit section 36 and the two U-shaped strips of the entry section 34 are all arranged in the same plane. Next, four orthogonal bends 56 are imparted to the configuration of Figure 3 so that the U-shaped strips of the inlet section 34 are parallel to each other and perpendicular to both the tip 32 and the exit section 36. Since these bends are parallel, not perpendicular to the developed length P of the raw material, the terminal 30 (without the contact 54) is completely formed before applying brazing to the contact 54 to the outlet section 36. This subsequent welding operation Strong contact is easily achieved because the U-shaped parallel strips of the inlet section 34 allow access to both the upper and lower surfaces of the outlet section 36. This, in turn, allows the contact 54 to be placed with precision in the output section 36. In contrast, it would be difficult to carry out the brazing operation for terminal 10 of FIG. 1 after completely forming the material premium because the inlet section 12 of the terminal 10 inhibits access to the lower surface of the outlet section 14. Although the present invention has been described with reference to one or more particular embodiments, those skilled in the art they will recognize that many changes can be made therein, without departing from the spirit and scope of the present invention. For example, in order for the blasting terminal 30 to function properly, it is not necessary for the U-shaped strips of the input section 34 to be constructed parallel to each other. Further, if desired, the inlet section 34 can be manufactured with only one U-shaped strip. Also, instead of configuring this single strip in a U-shape with a first end 40, a second end 42, and a central portion 44, the strip can be configured in a different in-form, such as a half-circle. Each of these embodiments and its obvious variations is contemplated as falling within the spirit and scope of the claimed invention, which are pointed out in the appended claims.