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Publication numberUS3544931 A
Publication typeGrant
Publication dateDec 1, 1970
Filing dateOct 24, 1968
Priority dateOct 24, 1968
Also published asUS3544932
Publication numberUS 3544931 A, US 3544931A, US-A-3544931, US3544931 A, US3544931A
InventorsPatel Nagar J
Original AssigneeWestinghouse Electric Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Circuit breaker with improved trip means
US 3544931 A
Images(5)
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Description  (OCR text may contain errors)

Dec. 1, 1970 I N. J. PATEL 3,544,931

CIRCUIT BREAKER WITH IMPROVED TRIP MEANS Filed Oct. 24, 1968 s Sheets-Sheet 1 FIG. I..

WITNESSES INVENTOR W Nogor J. Patel ATTORNEY N. J. PATEL Dec. 1, 1 970 CIRCUIT BREAKER WITH IMPROVED TRIP MEANS I Filed Oct. 24, 1968 5 Sheets-Sheet 2 NQE Dec. 1, 1970 J. PATEL 3,544,931

CIRCUIT BREAKER WITH IMPROVED TRIP MEANS Filed'oct. 24, 1968 5 Sheets-Sheet 4 CIRCUIT BREAKER WITH IMPROVED TRIP MEANS Filed Oct. 24, 1968 N. .J. PATEL Dec. 1, 1970 5 SheetsSheet 5 United States Patent Oflice 3,544,931 Patented Dec. 1, 1970 3,544,931 CIRCUIT BREAKER WITH IMPROVED TRIP MEANS US. Cl. 335-174 Claims ABSTRACT OF THE DISCLOSURE A circuit breaker comprises improved trip means automatically operable to open the breaker upon the occurrence of overload current conditions. A magnetic trip device comprises a movable keeper connected to an actuator which, when the movable keeper is released, moves as a unit to engage a trip extension that is carried on the breaker trip shaft to move the trip shaft and thereby effect opening of the breaker contacts. A magnetic trip device comprises a generally U-shaped unitary magnetic member and a movable keeper opposite the ends of the legs of the generally U-shaped unitary magnetic member with the bight portion of the generally U-shaped unitary magnetic member serving as a fixed keeper.

CROSS-REFERENCES TO RELATED APPLICATIONS This invention is an improvement over the invention disclosed in the application of Edmund W. Kuhn entitled Circuit Breaker With Improved Trip Means, Ser. No. 770,305, filed Oct. 24, 1968. The circuit breaker herein disclosed is more specifically described in the application of Fred Bould et al. entitled Circuit Breaker, Ser. No. 770,296, filed Oct. 24, 1968.

BACKGROUND AND OBJECTS OF THE INVENTION For certain applications of circuit breakers, it is desirable to provide a flux-transfer trip device of the type comprising a plurality of magnetic circuits with means for transferring magnetic flux from a first circuit to a second circuit to effect release of a movable keeper in the first circuit to thereby effect a tripping operation of the circuit breaker. An object of this invention is to provide an improved circuit breaker comprising a flux-transfer trip device and improved means providing a cooperative relationship between the movable keeper of the trip device and the operating mechanism of the circuit breaker.

Another object of this invention is to provide a circuit breaker with an improved flux-transfer type trip device that comprises a unitary U-shaped magnetic member, that serves as the pole pieces and fixed keeper, and that is constructed to to provide a magnetic circuit through the bight portion thereof that has a higher reluctance than another magnetic circuit that extends through portions of the legs of the U-shaped member and through a magnetic movable keeper that engages the free ends of the legs of the U-shaped member.

A more general object of this invention is to provide a circuit breaker with an improved flux-transfer type trip device that is reliable in operation and relatively easy to manufacture and to assemble into operating relationship with parts of the circuit breaker.

SUMMARY OF THE INVENTION An improved circuit breaker comprises a flux-transfer type trip device that, when pulsed by a momentary low energy electrical signal supplied under abnormal or over load conditions, will effect a tripping operation of the circuit breaker. The trip device comprises a pair of spaced magnetic pole pieces with a movable keeper positioned at the back end of the pole pieces and a fixed keeper positioned at the front end of the pole pieces. A permanent magnet structure is supported between the pole pieces and between the fixed and the movable keepers in order to supply magnetic flux. With the movable keeper in the set position the large majority of magnetic flux from the permanent magnet structure operates through a low reluctance magnetic circuit, that comprises the movable keeper, to work to maintain the movable keeper in the set position. The remainder of magnetic flux passes through a higher reluctance magnetic circuit that includes the fixed keeper. The pole pieces and magnetic structure are encapsulated in an insulating casing. An actuator is operatively connected to the movable keeper and extends through an opening in the trip device to the front end of the trip device where the actuator is formed with a head portion. A kick-out spring is supported in the opening in the trip device around the actuating rod to bias the movable keeper and actuating rod toward a tripping position. A pair of coils are connected in series and to the magnetic device in order to buck the magnetic flux through the low-reluctance magnetic circuit to thereby elfect a transfer of magnetic flux to the higher-reluctance magnetic circuit to effect release of the movable keeper. Upon release of the movable keeper, the kick out spring biases the movable keeper and actuating rod to a tripping position. The trip device comprises a trip member that is fixedly secured to a rotatable trip shaft of the circuit breaker and that is positioned under the head of the actuating rod. When the actuating rod is operated downward upon release of the movable keeper the head thereof engages the trip member to rotate the trip shaft to effect a tripping operation of the circuit breaker. The trip device also includes a resilient bell-crank type reset member that is pivotally supported at the front end of the trip device. The bell-crank type resilient reset member comprises a first leg that is positioned under the head of the actuating rod and a resilient second leg that extends into the path of movement of a lever member that moves with the movable contact between the open and closed positions. When the circuit breaker is tripped the lever member moves to the open position engaging the resilient .leg of the bell-crank type resilient reset member to pivot the reset member to a resetting position during which movement the other leg of the reset member engages the head of the actuating rod to pull the rod up to the reset position and to permit the trip member, that is fixedly secured to the trip shaft, to move back to the reset position under the bias of a reset spring. With the mounting of the trip member on the trip shaft and with the provision of a pivotally supported bell-crank type resilient reset member connected to the front of the trip device, the construction and positioning of parts is less critical and the trip device is readily assembled into operative relationship with the breaker. The trip member is provided with another leg that is actuated by a separate solenoid that may be remotely controlled to provide a shunt trip device. In one embodiment of the invention the pole pieces and fixed keeper are formed as a unitary U-shaped member of magnetic material with the higher reluctance path through the fixed keeper or bight portion being provided by forming a portion of reduced cross section in the bight portion of the unitary U-shaped member. This construction eliminates the need of a separate fixed keeper and makes the unit less sensitive to manufacturing and assembly variations.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end view, with parts broken away, of a circuit breaker constructed in accordance with principles of this invention;

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 IIIIII of FIG. 1;

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

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 shown in 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 openposition and the trip device in the reset position;

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;

FIG. 13 is an end elevational view of a Ushaped 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 bottom plan view of the member shown in FIG. 13; and

FIG. 16 is a top plan view of the movable keeper shown in FIG. 12.

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 5 is more specifically described in the above-mentioned application of Fred Bould et al., Ser. No. 770,296, filed Oct. 24, 1968.

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 confact 23 for each pole unit. Each of the movable contacts 23 is supported on a 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.

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 crank-shaft 71 in proximity to the opposite ends of the crank-shaft 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 application of Fred Bould et al., Ser. No. 770,296, filed Oct. 24, 1968. 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 support rod 81 and the center of the crank-shaft 71 so that the charged tension springs 79 are operating to bias the crank-shaft 71 in a counterclockwise direction. Counterclockwise movement of the crank-shaft 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 abovementioned application of Fred Bould et al., Ser. No. 770,296, filed Oct. 24, 1968. As can be seen in FIG. 2, the 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 counterclockwise direction 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 arms 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 cornpresses back-up springs 93 in the three pole units. As can be understood with reference to FIG. 5, the engagement of the closing cam 51 with theroller 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 9 5 (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 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 the springs 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 103 (FIG. 1) operates to rotate the trip shaft 63 clock wise 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 crankshaft 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 crankshaft 71 in a counterclockwise (FIG. 2) direction, and the roller 67 engages the latch 85 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 the charged position by the operation of the manually operable means 83 (FIG. 1) during which operation the crankshaft 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 application of Fred Bould et a1. Ser. No. 770,296, filed Oct. 24, 1968.

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, 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 mmediate closing operation. Thus, at the expiration of the tripping operation, when the closing springs 79 are charged, an operator can immediately press the closing means 91 to move the latch (FIG. 2) to release the roller 67 whereupon the circuit breaker will be operated from the position seen in FIG. 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-charged position, the circuit breaker can be tripped and then closed and then tripped again in rapid sequence.

The trip device 95 (FIGS. 7 and 12) comprises a housing and a magnetic device 107 supported on the housing 105. 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, 120, 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 trade name 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 139 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 has 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 shunttrip 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 leaf-spring 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 95 comprises two magnetic circuits. With the movable keeper 135 in the reset position engaging the pole pieces 111, 109, the permanent magnet structure 125 supplies magnetic flux which passes through the pole piece 109, movable keeper 135, pole piece 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 piece 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 135 is in the reset position the greater portion of the magnetic flux generated by the magnet structure passes through the one circuit including the movable keeper 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 circuit breaker by means of an overcurrent protective device of the type specifically described in the patent application of John David Watson et al., Ser. No. 765,584, filed Oct. 7, 1968. 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 flux 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 139 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 seen in FIG. 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 actuating rod 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 135 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 operate against the leaf spring 153 to operate the bellcrank reset member 145 to thereby lift the actuating rod 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 counterclockwise direction about the pivot of the armature 169 on the 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 member 181 having an opening 183 and a slot 184 in the bight portion 185 thereof. The unitary U-shaped magnetic member 181 may be used in the magnetic device 95 (FIG. 12) in place of the members 109, 111, 131, 129. In this embodiment, the opposite legs 187 and 189 of the mem her 181 serve as the pole pieces of the magnetic device; and the bight portion 185 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 movable keeper 135. The Ushaped member 181, which takes the place of the four members 109, 111, 131, 129, is a unitary structure 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.

I claim:

1. A circuit breaker comprising a stationary contact,

10 a movable contact cooperable with said stationary contact, a circuit-breaker mechanism releasable to effect opening of said contacts, a trip shaft in a latching posi tion latching said circuit-breaker mechanism and mov able to a tripping position to release said circuit-breaker mechanism, a magnetic trip device comprising magnetic pole-piece means, a magnetic fixed keeper at one end of said pole-piece means, a magnetic movable keeper at the other end of said pole-piece means, an actuator connected to said movable keeper and movable with said movable keeper, biasing means biasing said actuator and movable keeper to a tripping position, a permanent magnet structure supplying magnetic flux that operates in a first magnetic circuit through said pole-piece means and said movable keeper to maintain said movable keeper in a set position against said pole-piece means, means for transferring magnetic flux from said first magnetic circuit to a second magnetic circuit which is through said polepiece means and said fixed keeper to thereby effect release of said movable keeper, upon release of said movable keeper said biasing means biasing said movable keeper and said actuator to a tripping position wherein said movable keeper is spaced from said pole-piece means, a trip extension carried on said trip shaft, and upon movement of said movable keeper and actuator to said tripping position said actuator moving as a unit and engaging said trip extension to move said trip shaft to said tripping position to release said circuit-breaker mechanism.

2. A circuit-breaker according to claim 1, said magnetic device being constructed and arranged such that the magnetic reluctance in said second magnetic circuit is higher than the magnetic reluctance in said first magnetic circuit, said means for transferring magnetic flux from said first magnetic circuit to said second magnetic circuit comprising coil means energized upon the occurrence of overload current conditions to effect said transfer of magnetic flux, means automatically operating upon the occurrence of an opening operation of said circuit breaker to move said actuator and movable keeper back to the set position wherein said movable keeper engages said pole piece means, and upon movement of said movable keeper to said set position with said coil means deenergized magnetic flux automatically transferred from said second magnetic circuit to said first magnetic circuit to maintain said movable keeper in said set position.

3. A circuit breaker according to claim 2, said means for moving said movable keeper to said set position comprising a resilient reset member supported on said trip device, said circuit-breaker mechanism comprising a movable member movable between an open position and a closed position with said movable contact, and upon movement of said movable member to the open position during a tripping operation said movable member engaging said resilient reset member and operating said resilient reset member to operate said actuator and said movable keeper to said set position.

4. A circuit breaker according to claim 3, said mag netic device having opening means therein, said actuator comprising an elongated actuating rod having an actuating head at the front end thereof, means connecting said actuating rod to said movable keeper at the back end of said magnetic device, said resilient reset member comprising a bell-crank member supported on a fixed pivot on said front end of said magnetic device with a first leg of said bell-crank member being positioned under said actuating head and with a resilient leaf-spring member mounted on the second leg of said bell-crank member, and upon movement of said circuit breaker to said open position said rigid member moving against said leafspring to pivot said bell-crank member whereupon said first leg of said bell-crank member engages said actuating head to move said actuator and said movable keeper to the set position.

5. A circuit breaker according to claim 4, and said biasing means comprising a coil spring supported on said actuating rod within said opening means which coil spring engages a fixed spring support at one end thereof and said movable keeper at the other end thereof to bias said movable keeper and actuating rod toward the tripping position.

6. A circuit breaker comprising a stationary contact, a movable contact cooperable with said stationary contact, a circuit-breaker mechanism releasable to effect automatic opening of said contacts, a trip shaft in a latching position latching said circuit-breaker mechanism and movable to a tripping position to release said circuitbreaker mechanism, a magnetic trip device comprising pole-piece means of magnetic material, a fixed keeper of magnetic material supported at a first end of said polepiece means, a movable keeper of magnetic material at a second end of said pole-piece means opposite said first end, said magnetic device having opening means therein, an elongated actuating rod operatively connected at a first end thereof to said movable keeper and extending at thesecond end thereof past said fixed keeper, permanent magnet flux supplying means positioned between said fixed keeper and movable keeper and supplying magnetic flux that operates in a first magnetic circuit through said pole-piece means and said movable keeper to maintain said movable keeper in a set position against said polepiece means, means for transferring magnetic flux from said first magnetic circuit to a second magnetic circuit which is through said pole-piece means and said fixed keeper whereupon said movable keeper is released, biasing means operating upon release of said movable keeper to move said movable keeper and said actuating rod to a tripping position, said actuating rod comprising an actuating head that operates to effect release of said circuit-breaker mechanism upon movement of said actuating rod to the tripping position, a resilient bell-crank reset member supported for movement about a fixed pivot, said bell-crank reset member comprising a first leg positioned under said actuating head and a second leg comprising a resilient portion, said circuit-breaker mechanism comprising a rigid member movable with said movable contact between open and closed positions and upon movement of said rigid member to the open position said rigid member engaging said resilient portion of said bellcrank reset member to pivot said bell-crank reset member to a resetting position during which movement said one leg of said bell-crank reset member engages said actuating head to move said actuating rod and said movable keeper to reset position.

7. A circuit breaker according to claim 6, said magnetic device being constructed and arranged such that the magnetic reluctance in said second magnetic circuit is higher than the magnetic reluctance in said first magnetic circuit, said means for transferring said magnetic flux from said first magnetic circuit to said second magnetic circuit comprising coil means energized upon the occurrence of overload current conditions to effect said transfer of magnetic flux, and upon movement of said movable keeper to said reset position magnetic flux automatically transferring from said second magnetic circuit to said first magnetic circuit to work through said movable keeper to maintain said movable keeper and actuating rod in said reset position.

8. A circuit breaker comprising a stationary contact, a movable contact cooperable with said stationary contact, an operating mechanism releasable to effect automatic opening of said contacts, a magnetic trip device comprising a generally U-shaped unitary member of magnetic material, said U-shaped unitary member of magnetic material comprising a bight portion and a pair of generally parallel legs, a movable keeper opposite the ends of said legs, permanent-magnet flux supplying means positioned etween said bight portion and movable keeper to provide magnetic flux that'operates in a first magnetic circuit through said legs and said movable keeper to maintain said movable keeper in a set position against said legs, biasing means biasing said movable keeper away from said set position, said permanent-magnet flux supplying means providing magnetic flux that operates in a second magnetic circuit through said legs and said bight portion, the magnetic reluctance in said second magnetic circuit being higher than 'the magnetic reluctance in said first magnetic circuit whereby the majorportion of magnetic flux provided by said permanent magnet flux supplying means operates through said first magnetic circuit to maintain said movable keeper in said set position, means for effecting a transfer of magnetic flux from said first magnetic circuit to said second magnetic circuit to effect release of said movable keeper, and upon release of said movable keeper said biasing means biasing said movable keeper from said set position to a tripping position to effect release of said circuit-breaker mechanism.

9. A circuit breaker according to claim 8, said means for transferring magnetic flux from said first magnetic circuit to said second magnetic circuit comprising coil means energized upon the occurrence of overload current conditions to effect said transfer of magnetic flux, means automatically operating upon the occurrence of an opening operation of said circuit breaker to move said movable keeper back to the set position wherein said movable keeper engages said legs, and upon movement of said movable keeper to said set position with said coil means deenergized magnetic flux automatically transferring from said second magnetic circuit to said first magnetic circuit to work to maintain said movable keeper in said set position.

10. A circuit breaker according to claim 9, said bight portion of said U-shaped unitary member comprising a portion of reduced cross section to provide said higherreluctance of said second magnetic circuit.

References Cited Kramer 335-254 BERNARD A. GILHEANY, Primary Examiner H. BROOME, Assistant Examiner

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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3750059 *Jul 31, 1972Jul 31, 1973Westinghouse Electric CorpCircuit interrupting apparatus
US3754108 *Sep 10, 1971Aug 21, 1973Electrical Protection Co LtdCircuit breaker toggle mechanism with spring-biased latch plate
US3760307 *May 10, 1972Sep 18, 1973Westinghouse Electric CorpCircuit breaker with overcurrent trip switch
US4587390 *Jan 7, 1985May 6, 1986Golden Gate Switchboard Co.Vacuum circuit breaker
US4677269 *Jul 12, 1985Jun 30, 1987Square D CompanyIsolation switch having a locking bail arm
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
US5548261 *Mar 3, 1995Aug 20, 1996Eaton CorporationTrip device for a circuit breaker
Classifications
U.S. Classification335/174
International ClassificationH01H71/10, H01H83/20, H01H83/00, H01H71/12, H01H71/32
Cooperative ClassificationH01H71/32, H01H71/321, H01H83/20, H01H71/1072
European ClassificationH01H71/32