MXPA95003932A - Arc stack for a circuit breaker - Google Patents

Abstract

An arc stack for receiving a circuit breaker blade moveable between a closed position and an open position comprises a plurality of generally rectangular arc plates having substantially similar length and width dimensions and positioned substantially parallel to one another. The straight edges of the arc plates are in line with one another so that the arc stack is generally rectangular in shape. The arc plates have respective arc throats formed therein having a plurality of sizes so as to form a longitudinal passageway extending through the arc throats following the arc generated by the blade moving between the closed and open positions. The arc plates include sets of arc plates with the arc plates in each set having identical arc throats. The sets of arc plates are arranged in order of decreasing arc throat size with the set having the largest arc throats being positioned adjacent the circuit breaker blade in the closed position. The arc stack is formed in two sections with each section including a selected number of arc plates. The arc plates in each section are interconnected by a pair of side fibers engaging associated edges of the arc plates. The two sections are connected to form the arc stack by engaging the inner edges of the pair of side fibers of one section with mating inner edges of the pair of side fibers of the other section.

Description

ARC STACKING FOR A CIRCUIT CIRCUIT BREAKER Field of the Invention The present invention relates generally to circuit breakers and, more particularly, to an arc stack for a circuit breaker. BACKGROUND OF THE INVENTION Arc stacks receive, develop arc voltage and absorb energy released via a movable circuit breaker blade when moving from a closed position to an open position. One type of arc stack, designated in FIG. 1 with the reference numeral 100, includes a plurality of generally rectangular, identical, arranged and interconnected plates parallel to each other. The plates have arc grooves of identical shape, respectively, to form a passage for the movable blade. To maximize the • Performance of the arc stack, the passage formed by interconnecting the plates with individual arc grooves, respectively, follows the radius of the movable blade when opening it. This is achieved by laterally displacing identical arc plates to one another in the same direction so that the individual arc grooves follow the radius of the movable blade. In this way, the arch stack takes an elongated curved shape. A disadvantage of this type of arc stacking is that it is difficult to manufacture with automated equipment because its construction requires a complex manipulation of the circuit breaker components surrounding the arc stack. Another disadvantage of this type of arc stack is that it takes a considerable amount of space within the circuit breaker housing. Referring to the arc stack of Figure 1, for example, due to the irregular shape of the arc stack, it occupies an unnecessarily large volume within the housing. Moreover, there is a current effort to reduce the cost and size of circuit breakers while reducing the labor required to assemble and maintain the circuit breakers. SUMMARY OF THE INVENTION The present invention provides an arc stack that can be assembled in a relatively compact area within a circuit breaker housing. The present invention also provides an arch stack that is easily manufactured using automated equipment. The present invention further provides an arc flash that promotes improved interruption performance for the associated circuit breaker. The present invention also provides an arch stacking construction that is cost effective and easy to manufacture. In a particular embodiment, the above objectives are achieved by providing an arc stack for receiving a circuit breaker blade movable between a closed position and an open position, comprising a plurality of arc plates placed substantially parallel to each other. The arc plates have respective arc grooves having a plurality of sizes so as to form a passage extending through the arc grooves following the arc generated by the blade moving between the closed and open positions. A connector bracket is used to keep the arc plates substantially parallel to each other. 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 figures and the detailed description that follows. 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 side view of a type of arch stack of the prior art; Figure 2 is a side view of a double-break circuit breaker, including an arc stack embodying the present invention; Figure 3 is a perspective view of the arc stack of Figure 2, in accordance with the present invention; and Figure 4 is a side view of two assemblies that can be combined to form the arch stack of Figure 3. Although the invention is susceptible to various modifications and alternative forms, its specific embodiments have been shown as an example in the drawings and will be described in detail. However, it should be understood that it 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, the present invention is discussed in the context of an exemplary double break circuit circuit breaker, which uses an arc stack incorporating the principles of the present invention. The particular circuit breaker illustrated and described (Figure 2), however, should not be construed to limit the possible applications for the present invention, since these applications encompass a wide variety of circuit breaker types.

To fully appreciate the utility of the present invention, however, the double-break circuit breaker of Figure 2 will first be described, followed by a detailed description of a secondary arc stack 10 (in accordance with the present invention) generally sketched. in the circuit breaker of Figure 2. The circuit breaker of Figure 2 includes a circuit breaker base 14 carrying all the internal components of the circuit breaker. The current path through the circuit breaker starts at a line terminal 16, and from the line terminal 16 the current path passes through a flexible pig tail 18. The flexible pig tail 18 is attached to a secondary blade 20, a movable contact 22 mating with a stationary contact 24. The current flows through the movable and stationary contacts 22, 24 to the middle terminal 26, which is configured in an S-shape. The other side of the Middle terminal 26 includes another stationary contact 28 connected thereto. Positioned opposite the stationary contact 28 is a pair movable contact 30 attached to a primary blade 32. Current flows through the stationary and movable contacts 28, 30, through the primary blade 32, and towards one end of a connector or flexible, primary pig tail 34. The other end of the primary flexible connector 34 is attached to a bi-metal 36, which provides the thermal trip characteristics for the circuit breaker. Finally, the current flows from the bi-metal 36 through a charging terminal 38 and outwardly from the charging end of the circuit breaker via a nipple 40. The primary section of the circuit breaker includes the primary blade 32, a lever 42, a handle 44, a magnetic armature 46, a pig tail 34, and an arch stack 13. The secondary section includes the secondary blade 20, the pig tail 18, an extension spring 48, and the stacking secondary arc 10. In the illustrated circuit breaker, using conventional magnetic and thermal trip protection aspects, the primary section provides the breaking capacity for all current levels from one to approximately 3,000 amps without operational assistance from the secondary section . The magnetic armature 46 is brought to an anvil 50 during high current flow. This allows the firing lever 42 to disengage from the magnetic armature 46 and rotate to the firing position, which in turn allows the primary blade contact 30 to be separated from the stationary contact 28 to interrupt the flow of current. As the contacts 28, 30 are separated, an arc voltage is generated in the primary arc stack 13. A thermal trip via the bi-metal 36 results in the same sequence of events and, additionally, results in the shot 42 disengage from the magnetic armor 46.

The normal operation of turning on and off the primary blade 32 occurs in response to the rotation of the handle 44 in a clockwise or counterclockwise movement. In response to the rotation of the handle 44 in either direction, the primary blade 32 opens or closes the circuit via the primary movable contact 30 and the primary stationary contact 28. The rotation of the primary blade 32 is directly linked to the handle 44 for the normal operation of turning on and off the primary blade 32. Further, the secondary section is not affected by the normal operation of turning on and off the primary blade 32. The secondary blade contact 22 and the secondary stationary contact 24 They remain closed. As previously explained, the secondary section of the circuit breaker has a limited operation below 3,000 amperes of fault current. However, at current levels of more than 3, 000 amps, the secondary section begins to contribute to interruption performance. In particular, the secondary blade 20 derives contact force from the extension spring 48. The secondary blade 20 pivots about the knife pivot 52 with the extension spring 48 extended upon opening the secondary blade 20 in response to a fault current of more than one. of 3,000 amps. There is no linkage of the secondary blade 20 to the primary blade 32, but rather the operation of the secondary and primary blades 20, 32 is completely separate and independent. In response to the occurrence of a current fault greater than 3,000 amps, the constriction resistance of the secondary blade contact 22 and the secondary stationary contact 24 provide a magnetic force that tries to separate the contacts. Simultaneously, the current path configuration of the middle terminal 26 and the secondary blade 20 forms a magnetic burst loop that also attempts to separate the contacts 22, 24. The addition of both opening forces to the secondary blade 20 makes that the secondary blade 20 separates at the contacts 22, 24. Upon opening the secondary blade 20, the extension spring 48 begins to stretch. The extension spring 48 allows the secondary blade 20 to continue to open as long as the force to open the blade is greater than the extension force of the spring 48. Upon separation of the contacts 22, 24, an arc voltage is generated in the stack of secondary arc 10. The combination of the arc voltage generated by the secondary arc stack 10 and the arc voltage generated by the primary arc stack 13 causes these voltages to add up. This allows extremely rapid rise in arc voltage and also allows high arc voltage levels consistent with double-break circuit breakers. As the current failure level rises considerably above 3,000 amperes, the secondary blade 20 will move more quickly and higher. As the arc interruption and extinction occurs in the primary and secondary sections, the secondary blade 20 it is polarized to return to the closed position due to the polarization of the extension spring 48. The primary blade remains in the open or triggered position. At this point, the interruption of the failure is complete, with no opportunity to reset. For more information regarding the construction and overall operation of the circuit breaker shown in Figure 2, reference may be made to the patent application of the United States No. (CRC-11 / SQUC112), entitled "Circuit Breaker Having Double Break Mechanism", filed on the same date as the present, assigned to the same transferee and incorporated herein by reference. Figures 3 to 6 illustrate the secondary arc stack 10 which is used in the exemplary circuit breaker of Figure 1. The secondary arc stack 10 is assembled on the Z axis in the base 14 of the circuit breaker of Figure 2 More specifically, the secondary arc stack 10 is placed in the base 14 with the lower surface 54 abutting the bottom of the base 14 and the side 56 positioned adjacent and substantially parallel to one end of the middle terminal 26. In the As an assembled form of the circuit breaker, the secondary blade 20 extends to the side 58 of the arc stack having a longitudinal passage 60 formed therein. The secondary arc stack 10 is generally rectangular in shape and is formed by interconnecting a series of individual arc plates 62, 64, 66, 68, 70, 72 and 74. Except for the end arc plate 74, the arc plates Individuals have respective individual arc grooves therein formed by means such as metal stamping. The longitudinal passage 60 created by the individual arc grooves follows the arc generated by the secondary blade 20 around the knife pivot 52. The four arc plates closest to the middle terminal 26 are identical and are identified by the reference number 62 Adjacent to the four arc plates 62 are two identical arc plates 64 having a shorter arc throat than the arc throat of the arc plates 62. Similarly, the arc throat of the two identical arc plates 66 is shorter than the arc throat of the two identical arc plates 64, the arc throat of the two identical arc plates 68 is shorter than that of the two arc plates 66, the arc throat of the two identical arc plates 70 is shorter than that of the two arc plates 68, the arc throat of the two identical arc plates 72 is shorter than that of the two arc plates 70, and the end arc plate 74 has no throat of Arc. The anterior progression of the different arc profiles follows the arc of the secondary blade 20 around the knife pivot 52. One advantage of forming the secondary arc stack 10 of the arc plates having a progression of arc throat profiles that match The arc radius of the secondary blade 20 is that the arc stack 10 is compact, taking up a minimum of space. Furthermore, this progression of arc profiles allows the secondary arc stack 10 to be easily fabricated with automated equipment and to promote improved interruption performance. Fabricating the secondary arc stack 10 with automated equipment, in turn, reduces the cost of manufacturing the secondary arc stack 10. Referring to Figures 3 and 4, the secondary arc stack 10 is assembled from a lower section 76 and a top section 78. The lower section 76 of the secondary arc stack 10 includes eight arc plates 62, 64 and 66 secured by upper and lower side fibers 80, 82. The side fibers 80, 82 include locating holes 83 that they receive respective protuberances 85 extending from respective upper and lower edges of the arc plates 62, 64 and 66. A greater. In addition, the side fibers 80, 82 are positioned within respective rectangular grooves 87 extending from the outer outer arc plate 62 to the inner end arc plate 66 and formed from individual grooves at the respective upper and lower edges of the outer arc plate. all the arc plates 62, 64 and 66. The rectangular grooves 87 and the mating holes 85 promote a firm bond between the side fibers 80, 82 and the arc plates 62, 64 and 66, and retain the arc plates together as a whole. The upper side fiber 80 has a different profile than the lower side fiber 82. In particular, the upper side fiber 80 has two male pieces 84a and 84b projecting from the connector edge 86, while the lower side 82 only has a male piece 88. protruding from its connector edge (figure 4). Also, the upper side fiber 80 has two female pieces 90a and 90b formed on the outer edge 92, while the lower side 82 only has a female piece 94 formed on its outer edge. The upper section 78 of the secondary arc stack 10 has upper and lower side fibers with edge profiles identical to the edge profiles of the respective upper and lower side fiber fibers 80, 82 of the lower section 76. Therefore, they are indicated with the same reference numbers similar parts. A difference between the lower section 76 and the upper section 78 of the arch stack 10 is that the lower section 76 includes an arc plate more than the upper section 78. The upper section 78 only includes the seven arc plates 68, 70, 72 and 74. Another difference, as said previously, is that the seven arc plates 68, 70, 72 and 74 are configured with different arc grooves than the arc plates 62, 64 and 66. To connect the lower sections and upper 76, 78 together, the corresponding pieces along the connecting edges of the upper and lower side fibers in both lower and upper sections 76, 78 are paired. In particular, the male pieces 84a, 84b along the connector edge 86 of the upper lateral fiber 80 of the lower section 76 are linked with the respective female pieces 90a, 90b along the connecting edge of the upper side fiber of the upper section 78. Further, the male piece 88 along the connecting edge of the lower side fiber 82 of the lower section 76 is connected with the corresponding female piece 94 along the connecting edge of the lower side fiber of the upper section 78. By joining the lower and upper sections 76, 78, they appear as a single secondary arc stack 10, as shown in figure 3, with all the arc plates fitting together. Not only is the manufacturing cost of the secondary arc stack 10 reduced because it is produced by automated equipment, but the manufacturing cost is further reduced because it is produced from multiple sections, ie the lower section 76 and the upper section 78, it is time from only one section. Producing the secondary arc stacking 10 in multiple sections reduces the cost of all the equipment required to handle the arc stack 10 because less capacity is needed to handle the multiple sections. Moreover, the stamping tonnage required to stamp the arc plates is dramatically reduced in a set of multiple sections. Although the present invention has been described with reference to one or more particular embodiments, those skilled in the art will recognize that many changes may be made therein, without departing from the spirit and scope of the present invention. Each of these embodiments and their obvious variations are contemplated as falling within the spirit and scope of the claimed invention, which are set forth in the following claims.

Claims (16)

1. CLAIMS What is claimed is: 1. An arc stack for receiving a movable circuit breaker blade between a closed position and an open position, comprising: a plurality of arc plates placed substantially parallel to each other, said plurality of plates of arc having respective arc grooves thereon, said arc grooves having a plurality of sizes so as to form a passage extending through said arc grooves following the arc generated by the blade moving between the closed and open positions; and a connector support for maintaining said plurality of arc plates substantially parallel to each other.
2. 2. The arc stack of claim 1, wherein said arc plates are generally rectangular in shape.
3. The arc stack of claim 1, wherein said plurality of arc plates include at least seven sets of arc plates, the arc plates in each of said sets having arc grooves of substantially identical shape, said seven sets of arc plates being arranged in order of decreasing size of arc throat, the arc plates in each of said assemblies being placed adjacent to each other.
4. 4. The arch stack of claim 3, wherein the arc plates in one of said assemblies have a different arc throat size than the arc plates in each of the remaining assemblies.
5. The arch stack of claim 4, wherein said seven assemblies include two end assemblies positioned at opposite ends of the arch stack and five intermediate assemblies positioned between said two end assemblies, one of said two end assemblies having four plates of arc and the other of said two end assemblies having an arc plate.
6. The arch stack of claim 5, wherein each of said five intermediate assemblies includes two arc plates.
7. The arc stack of claim 1, wherein said connector support includes side fibers connected to opposite sides of the arc stack, each of said side fibers interconnecting associated edges of said arc plates.
8. The arch stack of claim 7, wherein the side fibers include positioning holes and said associated edges of said arc plates include protrusions that link said positioning holes in said side fibers.
9. 9. An arch stack, comprising: a first plurality of substantially parallel arc plates having respective arc grooves formed therein; a first connector support for interconnecting said first plurality of arc plates to form a first section; a second plurality of substantially parallel arc plates having respective arc grooves formed therein; a second connector support for interconnecting said second plurality of arc plates to form a second section; and interleaving members disposed in said first and second sections for connecting said first section to said second section.
10. The arc stack of claim 9, wherein said first connector support includes a first pair of side fibers connected to opposite sides of said first section, each of said first pair of side fibers interconnecting associated edges of said first plurality of plates of Arc.
11. The arc stack of claim 10, wherein said second connector support includes a second pair of side fibers connected to opposite sides of said second section, each said second pair of side fibers interconnecting associated edges of said second plurality of plates of Arc.
12. The arc stack of claim 11, wherein said first pair of side fibers includes positioning holes and said associated edges of said first plurality of arc plates include protrusions that link said positioning holes in said first pair of side fibers.
13. 13. The arch stack of claim 12, wherein said second pair of side fibers includes positioning holes and said associated edges of said second plurality of arc plates include protrusions that link said positioning holes in said second pair of side fibers.
14. The arch stack of claim 14, wherein said interlocking members include male pieces protruding from the inner edges of said first pair of lateral fibers and mating female pieces disposed along opposite internal edges of said second pair. of side fibers, said male pieces connecting said female pieces to connect said first section to said second section.
15. The arch stack of claim 14, wherein one of said first pair of side fibers includes two male pieces protruding from their inner edge and the other of said first pair of side fibers includes a male piece protruding from their inner edge , and wherein one of said second pair of side fibers includes two female pieces arranged along its internal edge and linking said two male pieces and the other of said second pair of lateral fibers includes a female piece arranged along its edge. internal and linking said male piece.
16. 16. A method of making an arc stack to receive a movable circuit breaker blade between a closed position and an open position, the method comprising the steps of: stamping a plurality of arc plates with arc grooves having different sizes; arranging the arc plates substantially parallel to each other in order of arc throat size so as to form a passageway extending through the arc grooves following the arc generated by the blade moving between the closed and open positions; and keeping the arc plates substantially parallel to each other using a connector support.