MXPA99004246A - Electrical switch device with conta finger guide - Google Patents

Abstract

The present invention relates to a contact guide member extending transversely to the contact fingers in the contact carrier of the electric switch apparatus and having spaced openings through which the contact fingers extend and are maintained in spaced relationship . The contact finger guide member is positioned to isolate the arched thumbs adjacent to the free ends of the contact fingers of the main contacts and the contact springs in order to protect the latter from the arc gases and the debris generated during the operation. bow formation. The openings in the contact finger guide member are elongated to allow differentially pivoting of the contact fingers, but not axial movement. The contact finger guide member slides in a molded cavity in the end face of the contact carrier and is captured by and moved with the contact fingers.

Description

ELECTRICAL SWITCH DEVICE WITH CONTACT FINGER GUIDE BACKGROUND OF THE INVENTION Field of the Invention This invention relates to an electrical switch apparatus, and in particular to such an apparatus with multiple contact fingers and a contact finger guide that maintains the spacing between the contact fingers during power interruption and blocks the passage of arcing gases backwards along the contact fingers. BACKGROUND INFORMATION Electric switching devices for power distribution systems include devices such as, for example, circuit breakers, network protectors, transfer switches, and disconnect switches. A common type of air circuit breaker has a molded case that houses multiple pole assemblies all driven by a common operating mechanism. Each pole includes a contact arm carrier pivoted by the operation mechanism between open and closed positions. The contact arm carriers hold contact arms having movable contacts that link stationary contacts with the contact arm carrier in the closed position. Typically, the contact arm is formed by several laminations of contact arm or contact fingers mounted on a common pivot pin in the carrier. The contact springs polarize the contact fingers against the stationary contacts in the closed position to provide contact pressure and to accommodate wear. There is a need to place the contact fingers laterally against magnetic loads during short circuit conditions. The contact fingers tend to oscillate from side to side due to the magnetic effects of the adjacent poles that are out of phase. This allows the moving contacts to slide over the stationary contacts. During the interruption, when the contact fingers are forming arcs, the magnetic forces tend to pull the ends of the fingers together toward the center of the pole. The fingers can bend, touch at their ends, and even weld together, losing their independent action. Separating fins can be molded into the carrier, but they are difficult to mold and often break during interruption. The spindle required to mold them limits their effectiveness when placing the contact fingers. In addition, there is a need to protect the contact springs from the debris generated by arcs, which can accumulate between the coils, limiting the displacement of the spring after the interruption. The contact carrier partially covers the springs, but there must be sufficient clearance to allow the fingers to pivot to the fully compressed position. There is therefore a need for an improved electrical switching apparatus with several parallel, spaced contact fingers arranged to prevent bending and welding of the contact fingers together during arcing. There is a further need for such an improved electrical switch apparatus that protects the contact fingers and the main contacts of arc gases and debris generated in separate contacts forming arcs. There is an associated need for such electrical switch apparatus that achieves these results with simple, economical arrangements of the parts. SUMMARY OF THE INVENTION These needs, and others, are met by the invention, which is directed to electrical switching apparatuses that include a contact guide member that extends transversely to the plurality of elongate contact fingers pivotally mounted on a carrier contacts that are mounted for movement between a closed position of movable contacts mounted on the contact fingers with stationary contacts, and an open position in which the contacts are separated. The contact guide member has spaced openings through which the contact fingers extend and remain spaced apart. Mounting means mount the contact guide member on the contact carrier for sliding movement by rotating the contact fingers about a pivot pin in the carrier. Preferably, the mounting means for the contact guide member is a cavity in the contact carrier in which the guide member is slidably received. The guide member is captured for sliding movement in the cavity by the contact fingers. In the preferred embodiment of the invention, the cavity in which the guide members slide is an end face of the contact carrier. The contact fingers are pivotally mounted on a pivot pin in the carrier and are biased around the pivot pin by contact springs. The guide member extends transversely to the contact fingers between arching thumbs on the free ends of the contact fingers and the contact springs. Guide members are also placed between the main contacts and the archery thumbs. In this way, the contact springs and the main contacts are protected against the arcing gases and the waste generated by the arcing contacts. The guide members have grooves through which the guide fingers extend. These grooves are dimensioned to allow the differential location of the movement of the contact fingers. The guide member restricts the lateral movement of the contact fingers and resists the bending of the contact fingers by the considerable magnetic forces generated during a high current short circuit. BRIEF DESCRIPTION OF THE DRAWINGS A full understanding of the invention can be achieved from the following description of the preferred embodiments, when read in conjunction with the accompanying drawings, in which: Figure 1 is an exploded isometric view of an air circuit breaker incorporating the invention. Figure 2a is a vertical section through the circuit breaker of Figure 1, shown in the fully closed position. Figure 2b is similar to Figure 2a, but illustrating touch of simultaneous contacts and thumbs during the closing sequence of the circuit breaker. Figure 2c is similar to Figure 2a, but showing the contact fingers about to break contact in the arching thumb. Figure 2d is similar to Figure 2a, but showing the contact carrier in the fully open position. Figure 3 is an isometric view of the contact carrier forming part of the circuit breaker with some parts removed for clarity and with the seal member removed and rotated. Figure 4 is an isometric view of the contact carrier from another angle, showing some parts removed as in Figure 3, and with the seal member in place but partially cut. Figure 5 is an isometric view of the underside of the contact carrier with the traction link assembly separated from the carrier. Figure 6 is a view similar to Figure 5, showing the traction link assembly linking the carrier. Fig. 7 is a schematic view showing the rotated contact carrier for disconnecting the traction link carrier to remove the circuit breaker. Figure 8 is an isometric view of the contact carrier with a contact guide member shown with broken portions and with the guide fingers in the retracted position. Figure 9 is a view similar to that of Figure 8, but showing the extended guide fingers. DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention is applicable to electrical switching devices such as, for example, circuit breakers, network protectors, transfer switches and disconnect switches, and will be described as being applied to a power circuit breaker. Referring to Figure 1, the power circuit breaker 1 of the invention has a housing 3 that includes a molded front box 5 and a rear case 7, and a cover 9. The exemplary circuit breaker 1 has three poles 10, the front and rear boxes 5, 7 forming three pole chambers 11. Each pole 10 also has an arc chamber 13 which is enclosed by a ventilated arc chamber cover 15. The circuit breaker 1 has an operating mechanism 17 which is mounted on the front of the front housing 5 and is enclosed by the cover 9. The operating mechanism 17 includes a large spring 18 which is charged to store energy to close the circuit breaker. The face plate 19 mounts a knock-to-close button 23, which is operated to discharge the closing spring to close the circuit breaker and a button that is pushed open to open the circuit breaker. The indicators 27 and 29 exhibit the condition of the loading spring and the open / closed state of the contacts, respectively. The loading spring is loaded by operation of the loading handle 31 or remotely by means of a motor operator (not shown). The common operation mechanism 17 is connected to the individual poles by a pole arrow 33 having a lobe 35 for each pole. As is conventional, the operating mechanism 17 includes a trip unit (not shown) which operates the operating mechanism to open all the poles of the circuit breaker by rotation of the pole arrow 33 in response to the predetermined characteristics of the current which flows through the circuit breaker.

As illustrated in Figures 2a-2d, each pole of circuit breaker 1 includes separable main contacts 37 comprising stationary main contacts 39 and movable main contacts 41. Stationary main contacts 39 are secured to a line conductor 43 that is mounted in and projects rearwardly from the rear case 7. The movable main contacts 41 are mounted in a moving conductor assembly 45. This assembly includes a contact carrier 47 in which a plurality of contact fingers 49 are pivotally mounted by a pivot pin 51. The movable main contacts 41 are fixed to the contact fingers 49 approximately midway between the pivot pin 51 and a first end or free end 53. Adjacent to the free end 53 of the contact fingers is a thumb of arc 55 forming a movable arcuate contact, which cooperates with a thumb block 57 which forms a contact stationary arc shape secured to the line conductor through an electrically conductive spacer 59 to form a set of arcing contacts. The moving driver assembly 45 further includes flexible shunts 61 which connect the contact fingers 49 with a load conductor 63 that also projects rearwardly from the rear case 7. As is conventional, an arc chute 65 is provided in the arc chamber 13. An arch runner 67 guides the arch of the thumb block to the arc chamber, where it is extinguished in a known manner. Turning to Figures 3, 4 and 5, in addition to Figures 2a-2d, the contact carrier 47 includes a molded body 69 and a pair of legs 71 secured to the ends of the body 69 by the bolts 70. The mounting pivots 73 project outward from the free ends of the legs 71. The pivot pin 51 is held at its ends at the legs 71. The contact fingers 49 are pivotally mounted on the pivot pin 51. The second ends 75 of the contact fingers 49 are biased against a stop spine 77 in the molded body 69 by means of a pair of contact springs 79 seated in recesses 81 in the molded body. The stop spine 77 has a contour that includes a recessed section 83 in the center of the stop spine. This allows the contact springs 79 to rotate the central contact fingers which are aligned with the recess 83 to project the first free ends or ends 53 further from the contact carrier than the other external contact fingers. The contact fingers 49 have enlarged sections 85 which extend radially outwardly from the mounting opening 87 which extends into slits 89 in the body of the carrier. The slits 89 are defined by fins 91 that extend between and axially separate the contact fingers on the pivot pin 51. The contact carrier 47 also includes a seal member 93 which is best observed in Figure 3, where it has been removed from carrier 47 and rotated 180 degrees. This seal member 93 has an arched base 95 from which a shield panel 97 extends outwardly. The fins 99 extend radially inward from the base of the seal to form slits 101. The end walls 103 in the base 95 they have confronting circular recesses 105 that link the ends of the pivot pin 51 to secure the seal member to the carrier body 69, as seen in Figure 4. In this assembled position, the fins 99 on the seal member 93 are They extend between the contact fingers 49 and align with the fins 91 in the carrier body to form a seal that prevents the passage of arc gases through the spaces between the contact fingers. As can be seen from Figure 2d, the seal panel 97 further restricts the flow of arc gases around the carrier 47 upon opening the contacts. Referring to figure 2a, the enlarged sections 85 of the contact fingers 49 have radial convex surfaces 107 that settle on radially concave surfaces 109 and 111 in the grooves 89 in the carrier body and slits 101 in the seal member. These surfaces serve to transmit reaction forces between the contact fingers 49 and the carrier body 69 to prevent bending of the pivot pin 51. This allows the pin 51 to be made of a lighter or more economical caliber material. Also, the supports for the pivot pin 51, namely the legs 71, have reduced loads to bear. This seating of the radial surfaces maintains the gas seal while allowing the contact fingers to rotate. As shown in Figure 2d, the contact carrier 47 is pivotally mounted for rotation to open and close the separable contacts 37. Support cavities 113 are formed by mating recesses 115 in the front case and the rear case 7 for the pivot 73 at the free ends of the legs 71. The carrier 47 is rotated about the pivots 73 by a link assembly 117 pivotally connected to the pole lobe 35 on the pole arrow 33. The operation of the circuit breaker 1 is as follows : with the contact carrier 47 rotated to the fully closed position shown in figure 2a, the separable contacts 37 are closed to complete a circuit including the line conductor 43, the fixed contacts 39, the movable contacts 41, the arms of contact 49, the flexible branches 61 and the load conductor 63. In this fully closed position, the arcing contacts are open. Also, in the fully closed position the second ends 75 of the contact arms are spaced from the stop spine 77. The contact springs 79 maintain contact pressure between the fixed and movable contacts 39, 41. When the circuit breaker is opened, it will start to open. circuit, the contact carrier 49 begins to rotate counterclockwise to the position shown in Figure 2b. In this position, with the carrier slightly spaced counterclockwise from the position of FIG. 2a, the contact springs 79 oscillate the contact fingers 49 in a clockwise direction around the separable contacts 37. and close the contacts that form arc. At this point, the current flows through both the separable contacts and the arcing contacts. As the contact carrier continues its rotation in the counter-clockwise direction during opening and reaches the position shown in FIG. 2c, the separable contacts have been separated. In addition, the second ends 75 of the external contact fingers 49o in Figure 2c are seated on the stop spine 77 and are thus rotated with the carrier to open the associated arc-forming contacts as well as the separable contacts. However, the second contacts of the central contact fingers 49c enter the recess 83 in the stop spine 77 and can therefore continue to rotate and keep the central contacts forming a closed arc. The continued rotation of the carrier 47 in the counterclockwise direction then results in the tracing of an arc between a thumb block 57 and the arc thumbs 55c in the central contact fingers only. This arch is then transferred by the archway 67 to the arch slide 65, where it is extinguished. Figure 2d shows the carrier in the fully open position with the advanced central contact fingers 49c. In this way, moving the carrier 47 to the closed position during the next closing cycle, the arcing contacts of the central contact arms will first touch followed by the arcing contacts of the external contact fingers. This will cause the contact fingers to oscillate to the position shown in Figure 2b, where both the arcing contacts and the separable contacts are closed. Upon reaching the carrier the fully closed position of Fig. 2a, the arcing contacts are separated and all current flows through the closed separable contacts 37. The circuit breaker 1 is constructed in a modular manner so that the same basic construction for a wide range of current ratings. For the highest rated current capacity, the maximum number of contact fingers is installed on the carrier. For such high current ratings, an additional set of flexible taps (not shown) can be connected between the contact fingers and the load conductor 63. In these applications, line 43 conductors and load conductors 63 are used. For minors Nominal current capacities, fewer contact fingers 49 are required. Under these circumstances, annular spacers 119 replace the contact fingers removed. In this way, as shown in Figures 3 and 4, the two outer contact fingers at each end of the carrier have been replaced by these annular spacers 119. These annular spacers perform two functions: they have the same radially convex surface 120 which seats against the radial surfaces 109 and 111 that the contact fingers replace to transmit reaction forces between the contact fingers and the carrier, and block the flow of arc gases. Another unique aspect of the circuit breaker 1 is the connection 121 between the carrier 47 and the pole arrow lobe 35. Referring to FIGS. 2a, 5 and 6, this connection 121 comprises the link assembly 117 and its pivotal connection to the pole lobe 35 and carrier 47. Link assembly 117 includes a pair of links 123 having offset ends 125 straddling the pole lobe 35 to which they are connected by a pin 127. A traction pin 129 extends transversely through the other ends of the links 123 and fixed thereto so that it can not rotate with respect to the links. The rear part of the carrier 47 is provided with a slot 131 dimensioned to pivotally receive the links 123. A circular passage 133 is molded in the contact carrier 47 transverse to the slot 131. A pair of slots 135 is the slit 131 lead to the passageway. 133. The tension pin 129 is capable of freely rotating in the passage 133, but is wedged by flat surfaces 137 to slide through the slots 133 only at a predetermined rotational orientation between the tension pin 129 and the contact carrier 47 This predetermined position between the traction pin 129 and the carrier 47 can not be established with the carrier pivotally mounted in the housing 3 for the normal range of rotation "between the closed and open positions, as shown in Figures 2a-2d. As previously discussed, the pins 73 on the legs 71 of the contact carrier are captured in the support cavities 113 formed by the recesses. The front box 7 is removed from the front case 5 and the rear layer 7. In order to install or remove the carrier 47, the rear case 7 is removed. This allows the pivot 73 to be moved to the right by rotation of the arcuate surface 139 in the Carrier body 69 centered on pivots 73 against surface 141 in front case 5, as shown in Figure 7. This aligns grooves 135 with flat surfaces 137 on traction pin 129 so that the contact carrier 47 is removed to the right so that the traction pin 129 passes through the slots 135. Preferably, the links 123 are provided with a cam surface 145 that abuts against the partition 143 in the housing for positioning the links 123, as shown in figure 7, for installation of a contact carrier 47 new or repaired. Figures 8 and 9 illustrate a contact finger guide member 147 which is provided in the contact carrier 47 to protect the main separable contact 37 from the arcing gases and the debris generated in the arcing contacts 57 and 59 during power interruption. The contact finger guide member 147 is a panel of electrically insulating material having a slot 149 for each of the contact fingers 49. The panel 147 is mounted on the carrier by a cavity 151 milled on the end face 153 of the body of the carrier 69. The panel 147 is captured for sliding movement in the cavity 151 by the contact fingers 49. As can be seen, the panel 147 extends transversely to the contact fingers between the arching thumbs 55 and the main contacts 41. It also separates the contact springs 79 from the arching thumbs 55. In this way, the springs and the main contacts they are protected from arc gases and waste generated during power interruption. The slots 149 are dimensioned to accommodate the differential rotation of the contact fingers 49. As discussed above, the central contact fingers project even more towards the stationary contacts when the carrier is in the open position than the external contact fingers. The slots 149 are sufficiently long so as not to interfere with this operation of the contact fingers. As can be seen in Figure 8, the finger guide member 147 is urged into the cavities 151 by the rotation of the contact fingers 49 relative to the body of the carrier 69 during the closure of the contacts. Upon opening the circuit breaker, the finger guiding member 147 is pulled out of the cavity 151 by turning the fingers 49 on the carrier 47, as shown in Figure 9. Although specific embodiments of the invention have been described in detail. , those skilled in the art will appreciate that various modifications and alternatives to those details can be developed in light of the global teachings of disclosure. Accordingly, the particular arrangements disclosed are intended to be illustrative only and not limiting as to the scope of the invention, to which the full scope of the appended claims and any and all equivalents thereof must be given.

Claims (14)

1. CLAIMS 1. Electric switch apparatus, comprising: a housing; and at least one pole, comprising: a stationary conductor having stationary contacts; a plurality of contact fingers, each having a movable contact; a contact carrier having a pivot pin in which said plurality of contact fingers are rotatably mounted in spaced parallel relation; first mounting means rotatably mounting said contact carrier for movement between a closed position in which said movable contacts link said stationary contacts, and an open position in which said movable contacts are spaced apart from said stationary contacts; contact springs mounted on said contact carrier and polarizing said plurality of contact fingers about said pivot pin to apply contact pressure to said movable contacts with said contact carrier in said closed position; and a contact finger guide member that extends transversely to said contact fingers and having spaced openings through which said contact fingers extend and are kept separate, and second mounting means mounting said guide member contact fingers in said contact carrier for sliding in said contact carrier when said contact fingers are rotated about said pivot pin. The electric switch apparatus of claim 1, wherein said second mounting means comprises a cavity in said contact carrier in which said contact finger guide member is slidably received. 3. The electrical switch apparatus of claim 2, wherein said contact carrier has an end face and said cavity is in said end face. The electric switch apparatus of claim 1, wherein said contact fingers have arcuate thumbs adjacent a free end and where said second mounting means mounts said contact finger guide member to slide transversely to said contact fingers between said arching thumbs and said contact springs. The electric switch apparatus of claim 4, wherein said second mounting means comprises a cavity in said contact carrier in which said contact finger guide member is slidably received. The electric switch apparatus of claim 1, wherein said contact fingers have a pivot opening through which said pivot and spaced arcuate thumbs extend from said pivot opening and wherein said movable contacts comprise main contacts. movable positioned between said pivot opening and said movable arcuate thumbs on said contact fingers and said second contact means mount said contact finger guide member to extend transversely to said contact fingers between said movable arcuate thumbs and said movable main contacts. The electric switch apparatus of claim 6, wherein said second mounting means mounts said contact finger guide member to extend transversely of said contact fingers between said arching thumbs and said contact springs. The electric switch apparatus of claim 1, wherein said openings in said contact finger guide member are dimensioned to accommodate a predetermined differential rotation of said contact fingers about, but not axial movement along, said pin. of pivot. The electric switch apparatus of claim 8, wherein said openings in said contact finger guide member are dimensioned such that said contact fingers engage and slide said contact finger guide member with rotation of said contact fingers while said predetermined differential rotation of said contact fingers is accommodated. 10. The electrical switch apparatus of claim 9, wherein said contact fingers have a pivot aperture through which said pivot pin extends, and arcuate thumbs in said elongate contact fingers spaced from said pivot aperture, and wherein said movable contacts comprise movable main contacts in said contact fingers between said pivot opening and said movable arcuate thumbs, said contact finger guide member extending transversely of said elongate contact fingers between said arcuate thumbs and said movable main contacts. The electric switch apparatus of claim 10, wherein said second mounting means comprises a cavity in said contact carrier in which said contact finger guide member is slidably received. The electric switch apparatus of claim 9, wherein said contact fingers have arcuate thumbs adjacent to a free end and wherein said second mounting means mounts said contact finger guide member to slide transversely to said contact fingers between said arching thumbs and said contact springs. The electric switch apparatus of claim 12, wherein said second mounting means comprises a cavity in said contact carrier in which said contact finger guide member is slidably received. 14. The electrical switch apparatus of claim 13, wherein said movable contacts comprise movable main contacts in said spaced contact fingers of said arcing thumbs and said cavity in which said contact finger guide member is slidably received is located between said arching thumbs and said movable main contacts as well as said contact springs.