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Publication numberUS3760307 A
Publication typeGrant
Publication dateSep 18, 1973
Filing dateMay 10, 1972
Priority dateMay 10, 1972
Also published asCA972403A, CA972403A1
Publication numberUS 3760307 A, US 3760307A, US-A-3760307, US3760307 A, US3760307A
InventorsN Patel
Original AssigneeWestinghouse Electric Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Circuit breaker with overcurrent trip switch
US 3760307 A
Abstract
A circuit breaker characterized by a pair of contacts operable between open and closed positions, a circuit breaker mechanism releasable to effect opening of said contacts, a trip structure for latching the circuit breaker mechanism in the closed position and for releasing the circuit breaker mechanism, the trip structure comprising a coil-actuated rod and an electromagnetic means responsive to a current overload for releasing the rod from a non-trip position, biasing means biasing the rod to the tripping position, switch means for opening and closing a circuit to auxiliary apparatus, the switch means having a trip lever movable between first and second positions of the switch means, and a cam lever operatively connected with the coil actuated rod and movable across the path of movement of the trip lever for moving the trip lever from the first to the second position, whereby upon movement of the rod to the tripping position, the switch means is actuated to one of the open and closed positions.
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llnite States t A [1 1 Patel 11] 3,760,307 [451 Sept. 18,1973

[ 1 CIRCUIT BREAKER Wl'lll OVERCURRENT TRIP SWITCH [75] lnventorz Nagar J. Patel, Pittsburgh, Pa.

[73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

[22] Filed: May 10, 1972 [21] Appl. No.: 251,957

[52] U.S. Cl 335/13, 335/17, 335/174, 337/79 [51] Int. Cl. 11011:: 71/46 [58] Field of Search 335/13, 17, 174; 337/79, 190, 174

[56] References Cited UNITED STATES PATENTS 2,821,586 l/1958 Bohn 335/13 3,284,731 11/1966 Nicol 335/13 3,544,931 12/1970 Patel 335/174 3,629,747 12/1971 Findley, Jr 3,594,668 7/1971 Clarke et a1. 335/13 Primary am flarqld Browne Attorney-A. T. Stratton et al.

51 ABSTRACT A circuit breaker characterized by a pair of contacts operable between open and closed positions, a circuit breaker mechanism releasable to effect opening of said 1 contacts, a trip structure for latching the circuit breaker mechanism in the closed position and for releasing the circuit breaker mechanism, the trip structure comprising a coil-actuated rod and an electromagnetic means responsive to a current overload for releasing the rod from a non-trip position, biasing means biasing the rod to the tripping position, switch means for opening and closing a circuit to auxiliary apparatus, the

switch means having a trip lever movable between first and second positions of the switch means, and a cam lever operatively connected with the coil actuated rod and movableacross the path of movement of the trip lever for moving the trip lever from the first to the second position, whereby upon movement of the rod to the tripping position, the switch means is actuated to onetof the open and closed positions.

'9 Claims, 19 Drawing Figures 1 \\\\\\\\\\\\\Tli Patented Sept. 18,1973 3,760,307

7 Sheets-Sheet 1 Patented *Se t. 18,- 1973' 7 sheets-Sheet 2 g Ill/1 hm Mm D.

Patented Sept. 18, 1973 3,1 0,307

7 Sheets-Sheet 3 FIG].

FIG l2. 1

Patented Sept. 18, 1973 Patented Sept. 18, 1973 v 'r Sheets-Sheet 6 Ill/I/ll/l/l/l/l/IJJ SN d 1 Patented Sept. 13, 1973 7 Sheets-Sheet 7 SOLID STATE TRIP I l l I l FIG.

SOURCE OF INCOMING EMERGENCY D POWER Q9 f-EMERGENCY MAIN BREAKER-I CIRCUIT BREAKER WITH OVERCURRENT TRIP SWITCH BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to circuit breakers and more particularly to a trip device having an additional function of opening or closing a circuit to auxiliary equipment such as a stanby circuit breaker.

2. Description of the Prior Art Circuit breakers having trip means for various purposes are disclosed in several related patents including US. Pat. Nos. 3,544,931 which issued Dec. 1, 1970 to Nagar J. Patel, 3,544,932 which issued Dec. 1, 1970 to Edmund W. Kuhn, and 3,590,192 whichissued June 29, 1971 to Fred Bould et al., all of which patents are assigned to the same assignee as the present application. Each of those patents satisfy certain problems which existed in the art prior to the conception of the invention embodied therein. It is recognized, however, that when a trip device opens a circuit through a circuit breaker, various consequences are incurred or problems solved thereby. Thus a circuit breaker may include an undervoltage trip device of the electromagnetic type where the operating coil for such a device is continuously energized as long as the applied voltage remains within a normal operating range to retain an associated movable magnetic member in a predetermined operating position against an associated biasing means, such as a spring. On the other hand, a circuit breaker may include an overvoltage trip device where for example,a ground fault occurs. In anticipation of those circumstances, circuit breakers are frequently provided with auxiliary circuit breakers which are automatically actuated to maintain service. However, where an overcurrent of a continuous nature such as a ground fault occurs, it is necessary to correct the cause of the overcurrent before reestablishing service.

Various types of switches and relays have been provided in association with circuit breaker trip structures for preventing the automatic closing of an associated circuit breaker upon the opening of another circuit breaker in response to an overload. However, such switches and relays havesometimes created more problems than they have satisfied. Accordingly, there is a need for switch means or an electric interlock .for blocking the automatic closing of an associated circuit breaker until an overload such as a ground fault is eliminated.

SUMMARY OF THE INVENTION In accordance with this invention it has been found that the foregoing problems may be overcome by providing a circuit breaker having a trip device of the electromagnetic type which is responsive to a current overload for actuating the circuit breaker mechanism to effect opening of the contacts, switch means operable by the trip device for opening or closing a circuit to auxiliary apparatus and having a trip lever movable between first and second positions of the switch means, a cam lever operatively connected with the trip device and being movable across the path of movement of the trip lever for moving the trip lever from the first to the second position, a latch lever in the path of movement of the trip lever for latching the trip lever. in the second remote from the latch lever, the latch lever including a strking edge and a catch edge for engaging and retaining the latch lever in the second position, and reset means for moving the latch lever to the unlatched position. e

The advantage of the device of this invention is that when a breaker trips due to overcurrent it makes or breaks two sets of contacts without the use of auxiliary relays, and in addition the device can be reset either manually through a pushbutton in the front of the breaker front plate or electrically through a remote switch. a

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end view, with parts broken away, of a circuit breaker;

FIG. 2 is a sectional view taken generally along the line II--II of FIG. 1;

FIG. 3 is a sectional view, with parts left out for the purpose of clarity, taken generally along the line III- --III of FIG. 1; 7

FIG. 4 is a view similar to FIG. 3 illustrating the parts in the tripped position; I

FIG. 5 is a view similar to FIG. 2, of part of the operating mechanism shown in FIG. 2, with the parts being shown in the spring discharged contact closed position;

FIG. 6 is a view similar to FIG. 5 with the parts being shownin the spring-discharged,contact-open position;

FIG. 7 is a sectional view taken generally along the line VII- VII of FIG. 1;

FIG. 8 is a partial view similar to FIG. 7, on an enlarged scale relative to FIG. 7, with the circuit breaker in the open position and the trip device in the reset position; p

FIG. 9 is a view similar to FIG. 8 with the circuit breaker in the closed position and the trip device in the reset position;

FIG. 10 is a view similar to FIGS. 8 and 9 with the trip device in the tripped position just prior to opening of the circuit breaker; FIG. 11 is a partial view illustrating the actuating position of the shunt-trip device;

FIG. 12 is a sectional view of part of the trip device seen in FIG. 7; I

FIG. 13 is an end elevational viewof a U-shaped magnetic member that serves as the pole pieces and fixed keeper in one embodiment of the invention; FIG. 14 is a top plan view of the member shown in FIG. 13;

FIG. 15 is a botton plan view of the member shown in FIG. 13;

FIG. 16 is a topplan view shown in FIG. 12; y

FIG. 17 is a side elevational view of the direct acting overcurrent trip switch in accordance with the principles of this invention;

FIG. 18 is a front view taken generally along the line XVIII-XVIII of FIG. 17; and

FIG. 19 is an electrical diagram of two circuit breakers and an electrical interlock.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, there is shown in FIGS. 1 and 2 a three-pole circuit breaker 5 comprising a housing structure 7 and a circuit-breaker structure 9 supported on the housing structure 7. The circuit breaker of the movable keeper 3 s is more specifically described in U.S. Pat. No. 3,590,192, issued June 29, 1971 to Fred Bould et al.

The housing structure 7 comprises a metallic base plate 11, a pair of spaced metallic side plates 13 secured to flanges of the base plate 11, a pair of metallic spaced center plates 17 secured to the base plate 11 and a back wall structure indicated generally at 19.

The circuit-breaker structure 9 is a three-pole structure comprising a stationary contact 21 and a movable contact 23 for each poleunit. Each of the movable contacts 23 is supported ona conducting contact arm 25 that is pivotally supported on a terminal conductor 27 by support means 29. In each pole .unit, a separate insulating connecting member 31 is'pivotally connected at one end thereof to the contact arm 25 and at the other end thereof to a lever 33 that is welded to a common jack shaft or tie bar 35. As can be seen in FIG. 1, the jack shaft 35 extends across all of the poles of the circuit breaker, and there is a separate lever 33 for each pole unit welded to the jack shaft 35. Only one of the contact structures is shown in FIG. 1. The contact structures for the centerpole and for the left-hand (FIG. 1) pole are left off of the drawing in FIG. 1 merely for the purpose of clarity. It can be understood that the contact structures for all three pole units are the same as the one contact structure shown in FIGS. 1 and 2.

The jack shaft 35 is supported for pivotal movement, about the elongated axis thereof, on the side plates 13 and center-plates 17. The connecting members 31, levers 33 and jack shaft 35 are part of a stored-energy spring closing mechanism 39 that is operable to close the contacts 23, 21. The mechanism 39 comprises a link member 41 that is pivotally connected, at one end thereof, to the lever 33 of the centerpole unit by means of a pin 43. The link 41 is pivotally connected, at the other end thereof, to a link 45 by means of a knee pivot pin 47. A roller member 49, that serves as a cam follower, is mounted on the pin 47 to cooperate with a closing cam 51. A link 45 is pivotally connected at the other end thereof to a latch member 53 by means of a pin 55 (FIG. 3). The latch member 53 is mounted for pivotal movement about a fixed pivot 57 that is supported on the left-hand (FIG. 1) center plate 17. A tension spring 59 is connected at one end thereof to a stationary pin 61, and operatively connected to the pin 55 at the other end thereof in order to reset the linkage following a tripping operation in a manner to be hereinafter described. As can be seen in FIGS. 3 and 4, the latch member 53 engages a trip shaft 63 that is a rod with a cut-out portion 65 near where the latch 53 engages the periphery of the trip'shaft 63. The cut-out portion 65 is provided so that when the trip shaft 63 is rotated in a counterclockwise direction the latch member 53 will be free to move to the tripped position seen in FIG. 4. The trip shaft 63 is supported for pivotal movement about the elongated axis thereof between one of the center plates 17 (FIG. 1) and one of the side plates 13. r

As can be seen in FIG. 1, the closing cam 51 comprises a pair of twin cam plates and a center spacer plate sandwiched together. The center spacer plate does not fill the space between the twin cam plates, and a roller latch member 67 (FIG. 2) is rotatably supported on and between the twin plates of the cam 51. The cam member 51 is fixedly secured to a crank-shaft 71 that is rotatably supported on suitable bearings that are secured to the center plates 17. A pair of crank arms 73 are fixedly mounted on the crankshaft 71 in proximity to the opposite ends of the crankshaft 71. A ratchet member 75 (FIG. 1) is fixedly mounted on the crank-shaft 87, and a pawl 77 is supported on one center plate to cooperate with the ratchet 75. A separate tension spring 79 is operatively connected at one end thereof to each of the crank arms 93. Each of the tension springs 79 is connected, at the other end thereof, to a rod 81 that is secured to the center plates 17. A handle operating mechanism, indicated generally at 83, is provided for manually charging the closing springs 79. The handle operating mechanism 83, is more specifically described in the abovementioned U.S. Pat. No. 3,590,192. A latch member 85 (FIG. 2) is pivotally mounted on a pin 87 and biased in a clockwise (FIG. 2) direction to the latching position, wherein the latch 85 engages the roller 67 to latch the closing cam 51 and crank-shaft 71 to prevent counterclockwise movement of the closing cam 51 and crank-shaft 71.

The circuit breaker is shown in FIG. 2 in the contactopen position with the stored energy closing springs 79 in the charged condition. As shown in FIG. 2, the spring support pins 89 of the movable ends of the tension springs 79 are below a line through the center of the spring supportrod 81 and the center of the crankshaft 71 so that the charged tension springs 79 are operating to bias the crankshaft 71 in a counterclockwise direction. Counterclockwise movement of the crankshaft 71 is prevented by the engagement of the latch member 85 with the latch roller 67 that is mounted on the closing cam 51. The latch member 85 is manually operated to the unlatching position by operation of closing means indicated generally at 91 and more specifically described in the above-mentioned U.S. Pat. No. 3,590,192.

As shown in FIG. 2, th roller 49 is positioned in a depression of the surface of the closing cam 51. When it is desired to close the circuit breaker, the closing means 91 is manually operated to pivot the latch 85 (FIG. 2) in a counterclockwisedirection to thereby release the roller 67. When the roller 67 is released, the closing cam 51 and crank-shaft 71 are free to rotate in a counterclockwise direction, and the closing springs 79, operating on the crank arm 73, operate to rotate the crank-shaft 87 from the charged position seen in FIG. 2 to the discharged positions seen in FIG. 5. With the latch 53 (FIG. 3)engaging the trip shaft 63 to prevent counterclockwise movement of the latch 53, the closing cam 51 will force the roller 49, and the link 41 to the closed position. During this closing movement of the link 41, the lever 33 (FIG. 2) of the center pole unit is forced in a counterclockwise direction to rotate the jack shaft 35 to the closed position seen in FIG. 5. As the jack shaft 35 rotates to the closed position all three of the levers 33 of the three pole units are moved with the jack shaft to the closed position forcing the connecting members 31 of the three pole units to force the contact arms 25 of the three pole units about the pivots 29 to the closed position wherein the movable contacts 23 engage the stationary contacts 21. This closing movement compresses back-up storage springs 93 in the three pole units. As can be understood with reference to FIG. 5, the engagement of the closing cam 51 with the roller 49 serves to prop the link member 41 in the closed position to thereby maintain the jack shaft 35 and contacts in the closed position.

With the contacts in the closed position and the closing springs discharged (FIG. 5) the circuit breaker may be automatically tripped open, in response to an overload above a predetermined value in any of the pole units, by operation of trip means indicated generally at 95 (FIG. 1), that will be hereinafter more specifically described. When actuated, the trip means 95 operates to rotate the trip shaft 63 in a counterclockwise direction from the latching position seen in FIGS. 3 and 5 to the unlatched or tripped positions seen in FIGS. 4 and 6. When the trip shaft 63 is rotated counterclockwise to the tripped position, the trip shaft moves to permit the latch member 53 to move in the notch 65 thereby permitting the latch member 53 to move in a counterclockwise direction about ,the pivot 57. The compressed contact springs 93 and an opening spring 99 then operate to move the contact arms 25 toward the open position which movement occurs because the pivot 55 is free to move from the position seen in FIG. 3 to the position seen in FIG. 4 so that the link 45 can move to the tripped position with the toggle 45, 41 collapsing to permit the lever 33 to move in a clockwise direction to the tripped open position. As can be understood with reference to FIGS. 2, 5 and 6 movement of the trip, shaft 63 to the tripped position permits the members 41, 45, 53 to move to the tripped position wherein the roller 49 and link 41 no longer restrain the lever 33 in the closed position, and thesprings 93, 99 operate to move the jack shaft 35 and the three contact arms 25 to the tripped-open position illustrated in FIG. 6.

The circuit breaker is trip free and the operator cannot manually restrain the breaker in a closed position when an overload occurs in any of the pole units.

With the circuit breaker in the tripped-open position seen in FIG. 6, the breaker is reset and the closing springs 79 are charged by operation of the manual operating means 83 (FIG. 1). In order to reset the circuit breaker and charge the closing springs 79, an operator cranks the manually operable means 83 to rotate the crank-shaft 71 through an angle of more than 180 from the spring-discharged position seen in FIG. 6 to the spring-charged operating position seen in FIG. 2. As the crank-shaft 71 moves to the position seen in FIG. 2, the roller 49 rides off of the peak of the cam 51 into the depression seen in FIG. 2. When the roller 49 is free to move into the depression of the cam 51, the spring 59 biases the latch 53 clockwise to move the latch 53 to the reset position pulling the links 45,41 and the roller 49 to the reset position, wherein the roller 49 is positioned in the depression of the cam 51 (FIG. 2). When the latch 53 (FIGS. 3 and 4) moves out of the notch 65 of the trip shaft 63, a spring 193 (FIG. 1) operates to rotate the trip shaft 63 clockwise from the position seen in FIG. 4 to the position seen in FIG. 3, whereupon the periphery of the trip shaft 63 again latches the latch member 53 to latch the parts in the reset position seen in FIGS. 2 and 3. As the crank-shaft 71 moves over the 184 line from the position seen in FIG. 6 to the position seen in FIG. 2, the springs 79, which are moved overcenter, take over to bias the crank-shaft 71 in a counterclockwise (FIG. 2) direction, and the roller 67 engages the latch 35 to latch the crank-shaft 71 in the charged position seen in FIG. 2 wherein the circuit breaker is prepared (FIG. 2) for another closing operation.

When the circuit breaker is in the contact-closed position with the stored energy closing springs 97 discharged, the spring closing means can be manually operated to thecharged position by the operation of the manually operable means 83 (FIG. 1). During that operation the crank-shaft 71 is rotated through an angle of slightly more than 180 (approximately 184) to charge the springs 79 during which movement the roller 49 rides on a fixed-radius surface of the cam 51 from the position seen in FIG. 5 to a position just short of the peak of the cam surface of the cam member 51. This charging operation is more specifically described in the above-mentioned US. Pat. No. 3,590,192.

With the parts in the contact-closed spring-charged position, the following sequence of operations can occur: Upon the occurrence of an overload of a predetermined value, the trip means 95 is operated to automatically rotate the trip shaft 63 to the unlatching position to release the latch member 53 and permit collapse of the toggle 41, 45 to effect an opening operation in the same manner as was hereinbefore described. With the toggle 41, 45 collapsed, the resetting spring 59 operates to draw the roller 49 into the depression of the cam 51 resetting the linkages 53, 41, 45, and the trip shaft 63, into the position seen in FIG. 2. The parts at the end of this tripping operation will be in the position seen in FIG. 2 wherein the mechanism is reset and relatched, and wherein the roller member 49 is in the depression of the cam 51 so that the parts are prepared for an immediate closing operation. Thus, at the expiration of the tripping operation, when the closing springs 79 are charged, an operator can immediately press theclosing means 91 to move the latch 85 (FIG. 2) to release the roller 67 whereupon the circuit breaker will be operated from the position seen inFIG. 2 to the closed position seen in FIG. 5 in the same manner as was hereinbefore described. With the parts in the closed position seen in FIG. 5, if an overload above the predetermined value occurs in any of the pole units, the trip means 95 will be automatically operated to rotate the trip shaft 63 to the tripped position to effect a tripping operation in the same manner as was hereinbefore described wherein the parts move to the position seen in FIG. 6. With the parts in the position seen in FIG. 6, another operation of the manual operating means 83 (FIG. 1)

. will be required in order to charge the closing springs 79 to provide a closing operation. Thus, when the circuit breaker is in the contact-closed spring-shargedposition, the circuit breaker can be tripped and then closed and then tripped again in rapid sequence.

The trip device (FIGS. 7 and 12) comprises a housing and a magnetic device 107 supported on the housing 195. The magnetic device 107 comprises a pair of magnetic steel pole pieces 109, 111, a conducting coil 113 around the pole piece 109, a conducting coil 115 around the pole piece 111 and four permanent magnet members 117, 119, 129, 121. The members 109, 111, 113, 115, 117, 119, and 121 are all potted in an insulating epoxy resin 123 which encapsulates these members and supports them as a unitary structure. The permanent magnet members 117, 119, 120, 121 form a permanent magnet structure indicated generally at 125 which is formed of the four members merely to facilitate assembly using readily available magnet members. The permanent magnet structure 125 is a rubber bonded barium ferrite permanent magnet material that is available under the trademark PLASTIFORM. A magnetic steel fixed keeper 129 is fixedly secured to the front end of the pole pieces 109, 111 with an insulating sheet 131 sandwiched between the fixed keeper 129 and pole pieces 109, 111 to provide a gap between the fixed keeper 129 and pole pieces 109, 111. The fixed keeper 129 and insulating sheet 131 are supported on the magnetic device by means of a pair of bolts 133 that extend through openings in the members 129, 131 and that are secured in the epoxy resin 123. A magnetic steel movable keeper 135 is provided to cooperate with the pole pieces 109, 111 at the back end of the pole pieces. As can be seen in FIG. 12, the fixed keeper 129, insulating sheet 131, epoxy'resin 123, and movable keeper 135 are provided with an aligned opening, and an elongated actuating rod 137, having an actuating head 139 at the upper end thereof, extends through the opening in these members. A nut 138- is secured at the lower end of the rod 137. A kick-out spring 140 is positioned on the rod 137 between the movable keeper 135 and a shoulder portion of the epoxy resin 123 to bias the movable keeper 135 and rod 137 toward the released tripping position seen in full lines in FIG. 12. A cup member 141 is secured at the lower end of the epoxy resin 123 to enclose the movable keeper 135 and rod 137 to prevent the collection of dust in this area. As can be understood with reference to FIGS. 7 and 12, the housing member having flanges at the outer ends of the legs thereof which are secured to the base plate 11 (FIG. 1) of the circuit breaker housing structure.

An inverted generally U-shaped supporting bracket 143 (FIG. 7) is fixedly secured to the bight portion of the member 105 and a resilient bell-crank reset member 145 is pivotally supported on and between the legs of the support bracket 143 by means of a pin 147. The bell-crank reset member 145 comprises a rigid lower leg 149 that is positioned under the actuating head 139 of the rod 137, and a rigid upper leg 151 that supports a resilient leaf spring member 153 at the free end thereof. A trip member 155, comprising a lower leg 157 that is positioned under the actuating head 139 of the rod 137 and an upper leg 159, is fixedly secured to the trip shaft 63 at a notch portion of the trip shaft. A shunt-trip device 161 is fixedly secured to one of the side plates 13 by means of a pair of bolts 163. The shunt-trip device 161 comprises a coil 165, a yoke 167 and an armature 169. The armature 169 is pivotally supported on one leg of a U-shaped bracket 171 and biased to the unactuated position seen in FIG. 7 by means of a spring 173. The armature 169 is positioned adjacent the leg 159 of the trip member 155. As can be seen in FIG. 7, the lever 33 for the left-hand (FIG. 1) pole unit is shaped with an extension that receives a rigid pin 175 that is fixedly secured to the lever 33 to cooperate with the leaf spring 153 in a manner to be hereinafter described.

Referring to FIG. 9, the jack shaft 35 and lever 33 are in the contact-closed position and the trip device 95 is in the reset position with the trip shaft 63 in the reset latched position. The bell-crank resilient reset member 145 is pivoted clockwise, by means of a torsion spring 176, to the position shown wherein the resilient leafspring 153 resets on the pin 175. The trip device 95 is in the reset position in which position the movable keeper 135 (FIG. 12) engages the pole pieces 111, 109 (as shown in broken lines in FIG. 12) to maintain the actuating rod 137 in the upper reset position shown in FIG. 9. The trip device comprises two magnetic circuits. With the movable keeper 135 in the reset position engaging the pole pieces 111, 109, the permanent magnet structure supplies magnetic flux which passes through the pole pieces 109, movable keeper 135, pole pieces 111 and through the magnet structure 125. Part of the magnet flux generated by the magnet structure 125 passes through another magnetic circuit which includes the magnet structure 125, the pole pieces 109, the gap 131, the fixed keeper 129, the gap 131, the pole piece 111, and through the magnet structure 125. Because the gap 131 provides a higher reluctance path through the magnetic circuit that includes the fixed keeper 129, when the movable keeper 125 is in the reset position the greater portion of the magnetic flux generated by the magnet structure 125 passes through the one circuit including the movable keeper 135 and the remainder of the magnetic flux passes through the other circuit that includes the fixed keeper 129. Thus, with the movable keeper 135 in the reset position, and with the coils 113, 115 not energized, the magnetic flux works to maintain the movable keeper 135 in the reset position.

The coils 113, 115 are connected in electrical series and pulsed by means of a DC current in response to abnormal or overload conditions in any of the three pole units of the circuit breaker by means of an overcurrent protective device of the type specifically described in U.S. Pat. No. 3,602,783 which issued Aug. 31, 1971 to Joseph C. Engel et al. The polarity of the coils 113, 115 is such that when the coils are pulsed the current in the coils serves to buck the magnetic flux in the circuit through the movable keeper 135 to raise the reluctance of the circuit in the movable keeper 135, whereupon magnetic fiux transfers to the magnetic circuit through the fixed keeper 129. Thus, when the coils 113, 115 are pulsed the movable keeper 135 is released such that the charged spring biases the movable keeper 135 and actuating rod 137 downward to the tripping position seen in full lines in FIG. 12 and illustrated in FIG. 10. As can be understood with reference to FIGS. 9 and 10, when the trip device 95 is operated to the tripping position the actuating rod 137 moves downward and the actuating head 139 thereof engages the leg 157 of the trip member to pivot the trip shaft 63 in a counterclockwise direction from the position seen in FIG. 9 to the position seen in FIG. 10. This movement of the trip shaft moves the notch portion 65 (FIG. 3) from the position seen in FIG. 3 to the position seen in FIG. 4 to effect a tripping operation of the circuit breaker in the same manner as was hereinbefore described. The parts are shown in FIG. 10 at the instant that the trip shaft 63 is moved to the tripping position and just prior to the actual movement of the contacts to the open position since the lever 33 is still shown in the closed position in FIG. 10.

Upon movement of the trip shaft 63 to the tripping position seeninFIG. 10, the circuit breaker will be tripped open and the lever 33 will move from the closed position seen in FIG. 10 to the open position seen in FIG. 8 in the same manner as was hereinbefore described. As the lever 33 pivots to the open position seen in FIG. 8, the pin will operate against the resilient leaf spring 153 to pivot the bell-crank resilient reset member 145 from the position seen in FIG. 10 to the reset position seen in FIG. 8 during which movement the leg 149 of the bell-crank reset member 145 engages the actuating head 139 of the actuatingrod 137 to move the rod 137 upward to the reset position wherein the movable keeper 135'again engages the pole pieces 109, 111. With the actuating head rod 137 in the upper position seen in FIG. 8, the trip shaft 63 is free to be reset in the same manner as was hereinbefore described. When the movable keeper 135 is moved to the tripped position seen in FIG. 12, the greater portion of magnetic flux generated by the magnet structure 125 passes through the pole piece 111, air gap 131, fixed keeper 129, gap 131, pole piece 111 back through the magnet structure 125, and a small portion of magnetic flux will leak through the air gap through the magnet structure 125, pole piece 109, gap at the lower end of the magnet structure, pole piece 111, to the magnet structure 125.

The coils 113, 115, which were only momentarily pulsed to effect a tripping operation, are not energized when the circuit breaker is tripped and they will not be energized when the circuit breaker is reclosed unless there is an abnormal or overload condition'in one of the pole units that would operate the protective relay to again energize the coils 113, 115. Thus, when the movable keeper 13.5 is reengaged, in the reset position, with the pole pieces 109, 111, magnetic flux will automatically transfer from the higher reluctance magnetic circuit that includes the fixed keeper 129 and gap 131 back through the lower reluctance magnet circuit that includes the movable keeper 135 so that the greater portion of the magnetic flux supplied by the magnet structure 125 will again work to hold the movable keeper 135 in the reset position until the coils 113, 115 are again pulsed. Thus, as the circuit breaker moves to the open position seen in FIG. 8, the lever 33 will oper* ate against the leaf spring 153 to operate the bell-crank reset member 145 to thereby lift the actuatingrod 137 to the reset position, and the magnetic flux will automatically operate to maintain the movable keeper in the reset position. When the circuit breaker is closed following an automatic tripping operation the lever 33 moves from the open position seen in FIG. 8 to'the closed position seen in FIG. 9, and the bell-crank resilient reset member 145 will pivot clockwise (FIG. 8).to the position seen in FIG. 9 under the bias of the spring 103. With the trip shaft 63 latched, the leg portion 157 of the trip member 155 is again positioned under the actuating rod 137 where the leg 157 may be engaged by the actuating head 139 to effect a tripping operation in the same manner as thus hereinbefore described:

The shunt trip device 161 is provided to enable an operator to trip the breaker by energizing the coil of the shunt trip device from a remote location. As can be seen in FIG. 7, the shunt trip 161 is'in'the unactuated position with the spring member 173 biasing the armature 169 in a counter-clockwise direction about the pivot of the armature 169 on th leg of the bracket 171. The coil 165 of the shunt trip 161 is connected to a suitable power source, and a well known type of normally open pushbutton switch may be connected to effect energization of the coil 165 from a remote location. Thus, when it is desired to trip the breaker, an operator can operate the switch to energize the coil 165 whereupon the armature 169 is attracted toward the yoke 167 against the bias of the spring 173 during which movement the armature 169 engages the leg 159 of the trip member 155 to pivot the trip shaft 63 from the reset position seen in FIG. 7 to the tripped position seen in FIG. 11. Upon movement of the trip shaft 63 to the tripped position seen in FIG. 11, the circuit breaker will be tripped in the same manner as was hereinbefore described.

Referring to FIGS. 13-15, there is shown therein a unitary inverted U-shaped magnetic steel mamber 181 having an opening 183 and a slotv 184 in the bight portion 185 thereof. The unitary U-shaped magnetic member 181 may be used in the magnetic device (FIG. 12) in place of the members 109, 111, 131, 129. In this embodiment, the opposite legs 187 and 189 of the member 181 serve as the pole pieces of the magnetic device; and the bight portion serves as the fixed keeper. Except for the use of the member 181 in place of the members 109, 111, 131, 129, the magnetic device is the same as that specifically shown in FIG. 12. The opening 183 is provided for receiving the actuating rod 137. The slot 184 provides a portion of reduced cross section (opposite the end of the slot) at 190 in order to provide that the magnetic circuit through the fixed keeper 185 will have a higher reluctance than the magnetic circuit through the movablekeeper 135. The

U-shapedmember 181,'which takes the place of the four members 109, 111, 131, 129, is a unitarystructure that is more economically manufactured and assembled into the magnetic device 95. The magnetic device with the member 181 therein, in place of the four members 109, 111, 131, 129, operates in the circuit breaker in the same manner as was hereinbefore described with reference to FIGS. 1-12.

The foregoing is the subject matter of abovementioned US. Pat. No. 3,544,931, issued Oct. 24, 1968 to Nagar l. Patel. i

In accordance with the invention of this application, it has been found that an electrical interlock may be provided between the circuit breaker 5 and other associated electrical apparatus such as a standby circuit breaker. For that purpose,'as shown in FIGS. 17 and 18, an interlock generally indicated at 200 is mounted adjacent to the magnetic device 95. The interlock includes a cam lever 201, a plurality of electric switches or microswitches 202, 203, and 204, a trip lever 205, and a latch lever 206. I l

The cam lever 201 includes a mounting flange 207 which is secured in a suitable manner, such as by screws 208, to the bell-crank reset member 145. As shown in FIG. 18, the cam lever 201 is inclined at an angle to the plane of FIG. 17 so that as the leg 151 rotates clockwise to the position shown in FIG. 9, the cam lever 201 engages a bracket 209 on the trip lever 205 and moves the lever 205 counterclockwise to the left, as shown in FIG. 18.

Although the three microswitches 202, 203, and 204 are disclosed, it is understood that agreater or lesser number of such switches may be used depending upon the number of functions performed by the interlock. More particularly, the microswitches 202-204 are mounted on amounting plate-210 having a footer 211 which is secured by suitable means such as screws 212 on the base plate 11. Insulating spacers 213 are disposed between the plate 210 and the switches 202-and 204 as well between the switches 202 and 203.,Each switch is provided with terminals 214 and 215 to which lead wires are attached in a conventional manner. Each switch is provided with a trip lever including trip levers 216, 217, and 218, respectively, for the microswitches 202, 203, and 204. As shown in FIG. 17, the upper ends of levers 216 and 217 are secured to the trip lever 205 in a suitable manner such as by rivetting. An arm 219 (FIG. 18) extends to the left of the trip lever 205 and terminates at a location proximate to the upper end of the trip lever 218. Each microswitch 202, 203, and 204 may be normally on or normally off depending upon its desired function in the circuit. Accordingly, when the cam lever 201 moves the trip lever 205 counterclockwise to the left (FIG. 18), all of the switches 202, 203, and 204 are actuated to either on or off conditions as set forth hereinbelow.

The latch lever 206 is pivotally mounted at 220 on a U-shaped frame 221 which, in turn, is mounted on a flange 222. The latch lever 206 is movable between the upper position shown in FIG. 18 and a lower brokenline position 206a. The latch lever 206 includes a down-turned flange 223 having a strike edge 224 and a latch edge 225. When the interlock 200 is disposed in the position shown in FIG. 18, the strike edge 224 is disposed on the upper end of the trip lever 205 in which position it is biased by a coil spring 226 which extends between the opposite end of the latch lever 206 and the upper end of the flange 222. As the cam lever 201 moves the trip lever 205 counterclockwise to the broken line position shown in FIG. 18, the upper end of the lever 205 clears the left end of the strike edge 224 and the latch lever 206 drops to the broken line position 206a, whereby the latch edge 225 engages and retains the trip lever 205 in place. During that movement of the lever 205, the microswitches 202-204 are operated as indicated hereinbelow.

When it is necessary to reset the interlock, it may be reset either electrically or manually. Electrical resetting is obtained by providing an electromagnetic means including a coil 227 and a magnetic core 228 within the U-shaped frame 221. For that purpose, one of the microswitches such as switch 204 is connected in series with the coil 222. Thereafter a remote reset button (not shown) is pushed in order to energize-the coil 222 through the closed micro-switch 204. As soon as the latch lever 206 lifts up in response to the magnetic field generated in the core 228, the upperend of the trip lever 205 is released from the latch edge 225 and the trip lever 205 returns to the solid line position as shown in FIG. 18, thereby cutting off current supplied through the normally open microswitch 204. v

In the alternative the interlock 200 may be reset manually by providing a flange 229 on one side of the latch lever 206 and a pushbutton 230, the latter of which is mounted in a front cover 231 of the circuit breaker. Inasmuch as the flange 229 is inclined downwardly and inwardly (to the right as viewed in FIG. 17), when the inner end of the pushbutton 230 strikes the flange 229, the resulting vector force causes the latch lever 206 to rise to the unlatched position, as shown in FIG. 18.

The purposes of the remaining microswitches 202 and 203 may include the following. The switch 202 may be used to actuate an annunciator such as a bell, signal light, or both.

One important application of the microswitch 203 may be to prevent the actuation of an automatic closing operation of an associated circuit breaker in a circuit breaker system, such as an automatic transfer system as shown in FIG. 19. Referring to FIG. 19, the main contacts of the circuit breaker 52 -N are normally closed and the main contacts .of the emergency'circuit breaker power, as shown in FIG. 19. If a loss of voltage should be sensed by the undervoltage trip device UV associated with the normal circuit breaker 52-N, the normal circuit breaker 52-N would be tripped open by the operation of the undervoltage trip device UV as described in detail in my US. Pat. No. 3,611,215 which issued Oct. 5, 1971. In that event, the normally closed overcurrent trip switch OTS associated with the normal circuit breaker 52-N will not be actuated and remain closed since the circuit breaker 52-N will be actuated or tripped open by the undervoltage trip device UV independently of the trip device associated with the circuit breaker 52-N, which responds only to overcurrent conditions such as the trip device previously described, and as described in detail in the last-mentioned patent. It is to be noted that the above overcurrent trip switch OTS, which may comprise the microswitch 203 of the interlock 200 previously described in detail, is connected electrically in series with the closing spring release coil SR associated with the emergency circuit breaker 52-E shown in FIG. 19. The latter series circuit also includes an auxiliary contact 52-N which is normally closed when the main contacts of the normal circuit breaker 52-N are open and which is open when the main contacts of the circuit breaker 52-N are closed. When the main contacts of the normal circuit breaker '52-N are tripped open in response to an undervoltage condition as just indicated, the overcurrent trip switch OTS associated with the circuit breaker 52-N remains closed and the auxiliary contact 52-Na associated with the circuit breaker 52-N closes to thereby automatically energize the closing spring release coil SR associated with the emergency circuit breaker 52-E and actuates a closing operation of the emergency circuit breaker 52-E.

On the other hand, if the normal circuit breaker 52-N is tripped open in response to an overcurrent condition in the electrical circuit associated with the load indicated in FIG. 19, the overcurrent trip switch OTS associated with the normal circuit breaker 52-N will be actuated open and prevent the automatic energization of the closing spring release coil SR associated with the emergency circuit breaker 52-E even if the auxiliary contact 52-Na connected in series with the spring release coil SR associated with the emergency circuit breaker 52-E is actuated to the closed operating position by the opening of the normal circuit breaker 52-N.

In summary, the interlock 200 as disclosed permits control operations which distinguish between an automatic tripping operation of a circuit breaker due to overcurrent conditions in the protected load circuit and opening operations of the. circuit breaker other than in response to an overcurrent condition, such as in the case of an undervoltage operating condition as just described.

What is claimed is:

l. A circuit breaker comprising a pair of separable contacts operable between open and closed positions, a circuit breaker operating mechanism releasable to effect opening and closing of said contacts, the circuit breaker operating mechanism comprising a jack shaft movable between first and second positions corresponding to open and closed positions of the contacts, a trip shaft in a latching position latching said circuit breaker mechanism and movable to a tripping position to release said circuit breaker mechanism and actuate the opening of said contacts, a trip device comprising a coil-actuated rod and an electromagnetic means responsive only to current overloads for releasing the rod from a non-trip position, the trip device being responsive to movement of the jack shaft to the first position thereof, biasing means biasing said rod to a tripping position, switch means for opening or closing a circuit to auxiliary apparatus and proximate to the trip device, the switch means having a trip lever movable between first and second positions of the switch means, and a cam lever operatively connected with the coil-actuated rod and being movable across a path of movement of the trip lever for moving the trip lever from the first to the second position, whereby upon movement of the rod to the tripping position the switch means is actuated to one of the open and closed positions.

2. The circuit breaker of claim 1 in which a latch lever is disposed in the path of movement of the trip lever for latching the trip lever in the second position.

3. The circuit breaker of claim 2 in which the lever is biased in the latching position.

4. The circuit breaker of claim 2 in which the cam lever is biased in its path of travel remote from the latch lever.

5. The circuit breaker of claim 4 in which the cam lever is inclined at an angle to its direction of travel.

latch 6. The circuit breaker of claim 5 in which the latch;

the latch lever from thy latched position.

Patent Citations
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US3284731 *Oct 10, 1963Nov 8, 1966Heinemann Electric CoAuxiliary switch responsive to the movement of the circuit breaker linkage
US3544931 *Oct 24, 1968Dec 1, 1970Westinghouse Electric CorpCircuit breaker with improved trip means
US3594668 *Jan 2, 1970Jul 20, 1971Texas Instruments IncRemote control circuit breaker
US3629747 *Mar 26, 1970Dec 21, 1971Westinghouse Electric CorpElectromagnetic trip device for circuit interrupters
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3863043 *Nov 1, 1973Jan 28, 1975Allis ChalmersOperating device for switches or the like
US4677269 *Jul 12, 1985Jun 30, 1987Square D CompanyIsolation switch having a locking bail arm
US4743876 *Jul 24, 1987May 10, 1988Westinghouse Electric Corp.Circuit interrupter with undervoltage trip mechanism
US4766270 *Jul 12, 1985Aug 23, 1988Square D CompanyLimited force interlock mechanism
US5192934 *Nov 6, 1991Mar 9, 1993Westinghouse Electric Corp.Circuit breaker having a trip actuator
US5502286 *May 25, 1994Mar 26, 1996General Electric CompanyBell alarm and lock-out for high ampere-rated circuit breakers
US6040746 *Dec 30, 1998Mar 21, 2000Eaton CorporationActuation mechanism for trip actuated breaker auxiliary multiple microswitch
US7557681 *Apr 9, 2007Jul 7, 2009Eaton CorporationElectrical switching apparatus accessory sub-assembly employing reversible coil frame, and accessory and electrical switching apparatus employing the same
US20040079626 *Oct 16, 2003Apr 29, 2004Ataul HaqSmart/variable circuit breaker for automotive and other applications
US20080246564 *Apr 9, 2007Oct 9, 2008Whitaker Thomas AElectrical switching apparatus accessory sub-assembly employing reversible coil frame, and accessory and electrical switching apparatus employing the same
Classifications
U.S. Classification335/13, 335/17, 335/174, 337/79
International ClassificationH01H51/10, H01H71/46
Cooperative ClassificationH01H2071/467, H01H71/46, H01H51/10
European ClassificationH01H51/10, H01H71/46