US3525058A

US3525058A - Circuit breaker with improved trip means

Info

Publication number: US3525058A
Application number: US725298A
Authority: US
Inventors: John J Astleford Jr
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1968-04-30
Filing date: 1968-04-30
Publication date: 1970-08-18
Anticipated expiration: 1987-08-18

Description

Auggl8, 1970 J. J. ASTLEFORD, JR 3, 2

CIRCUIT BREAKER WITH IMPROVED TRIP MEANS Filed April 30, 1968 v5 Sheets-Sheet 1 "OFF" FIGLL WITNESSES INVENTOR John J. Asfleford ,Jn

Aug. 18, 1970 J. J. ASTLEFORD, JR 3,525,058

CIRCUIT BREAKER WITH IMPROVED 'VIIRIP MEANS Filed April 30, 1968 I 5 Sheet-Sheet IIOFFII llllllllll n Aug. 18, 1970 J. J. ASTLEFORD, JR 3,525,058

CIRCUIT BREAKER WITH IMPROVED TRIP MEANS Filed April 30, 1968 5 Sheets-Sheet?) Aug. 18, 1970 J. J; ASTLEFORD, .JR

CIRCUIT BREAKER WITH IMPROVED TRIP MEANS Filed April :50. 1968 5 Sheets-Sheet 5 FIGS.

III/[III] United States Patent 3,525,058 CIRCUIT BREAKER WITH IMPROVED TRIP MEANS John J. Astleford, Jr., Sharon, Pa., assignor to Westinghouse Eleclric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Apr. 30, 1968, Ser. No. 725,298 Int. Cl. H01h 75/12 US. Cl. 335-35 15 Claims ABSTRACT OF THE DISCLOSURE A circuit breaker is provided with improved trip means comprising a thermal trip operable with a time delay in response to a sustained overload above a first predetermined value to effect automatic opening of the breaker and an electromagnetic trip operable instantaneously upon the occurrence of an overload above a second predetermined value to effect automatic opening of the breaker.

PRIOR ART AND BACKGROUND OF THE INVENTION In the patent to Leonard et al., Pat. No. 2,686,242, there is disclosed a circuit breaker comprising a contact arm that is latched at one end thereof by means of a primary latch member. The breaker comprises an operating mechanism operable between two operating positions to pivot the contact arm about the latched end thereof between open and closed positions with a snap-action. A thermal trip comprises a bimetal movable with a time delay upon the occurrence of an overload above a first predetermined value to release a spring biased secondary latch member that moves to strike the primary latch member to unlatch the contact arm whereupon means operates to move the contact arm to a tripped Open position. This invention is an improvement over the circuit breaker of the Leonard et a1. patent in that an improved electro-magnetic trip is provided to operate instantaneously upon the occurrence of a severe overload above a second predetermined value to operate the primary latch member to release the contact arm to effect a tripping operation.

In the patent to Hodnette et al., Pat. No. 2,586,429, there is disclosed a circuit breaker comprising a contact arm that is pivotally supported on a fixed pivot. A latched toggle-type operating mechanism is manually operable to collapse the toggle to move the movable contact arm to the open position with a snap action and to erect the toggle to move the contact arm to the closed position with a snap-action. A thermal trip comprises a bimetal that is movable with a time delay upon the occurrence of an overload above a first predetermined value to unlatch a secondary latch which then strikes a primary latch to release a releasable member to effect collapse of the toggle and opening of the contacts. This invention is an improvement over the circuit breaker of the Hodnette et al. patent in that an improved electromagnetic trip is provided for instantaneously releasing the trip member upon the occurrence of a severe overload above a second predetermined value to effect opening of the contact arm.

This invention is also on improvement over the art disclosed in the following patents: Swingle, Pat. No. 2,329,362; Jackson, Pat. No. 2,312,168; Cole, Pat. No.

ICC

2,673,264; Christensen et al., Pat No. 2,811,605; Archer et al., Pat. No. 3,205,325.

SUMMARY OF THE INVENTION In one embodiment of the invention, an elongated movable contact arm is pivotally connected intermediate the ends thereof to an operating link of a spring-type operating mechanism. The elongated movable contact arm is provided with a contact at one end thereof for cooperating with a stationary contact. The contact arm is latched at the other end thereof by means of an elongated primary latch member that is pivotally supported intermediate the ends thereof. The spring-type operating mechanism is manually operable between open and closed positions to pivot the movable contact arm about the latched end between open and closed positions with a snap-action. Trip means is provided comprising a thermal trip and an electromagnetic trip. The thermal trip comprises a secondary latch member that is latched by a bimetal and that is spring-biased toward a tripping position. Upon the occurrence of a sustained overload above a first predetermined value, the bimetal flexes with a time delay to release the secondary latch whereupon the secondary latch moves to strike one end of the primary latch to pivot the primary latch to a position releasing the latched end of the elongated contact arm whereupon spring means biases the elongated contact arm about the pivot of the operating link to a tripped-open position. The electromagnetic trip operates instantaneously upon the occurrence of a severe overload above a second predetermined value to strike the opposite end of the primary latch member to pivot the primary latch member to a releasing position to effect a tripping operation of the circuit breaker.

In another embodiment of the invention, a circuit breaker is provided with an elongated contact arm that is mounted for pivotal movement about a fixed pivot at one end thereof and that is provided with a contact at the other end thereof. A spring-type operating mechanism comprises a toggle that is pivotally connected, at one end thereof, to the contact arm intermediate the ends of the contact arm. The toggle is pivotally connected to a trip member at the other end thereof. The trip member is latched in an operating condition by means of a pivotally mounted primary latch member. With the trip member latched, the operating mechanism is manually operable to an off position to collapse the toggle to open the contact arm with a snap-action and manually operable to an on position to erect the toggle to move the contact arm to the closed position with a snap-action. A thermal trip comprises a bimetal that latches a secondary latch member and that flexes to a releasing position upon the occurrence of an overload above a first predetermined value to release the secondary latch member which then moves to strike one end of the primary latch member to release the trip member to effect collapse of the toggle and opening movement of the contact arm. The other end of the primary latch member comprises an armature portion that is disposed opposite a conductor that is secured to contact arm on the side of the pivot of the contact arm that is opposite the side that carries the movable contact. Upon the occurrence of an overload above a second predetermined value the armature portion is attracted toward the conductor to move the primary latch member to a releasing position whereupon the circuit breaker is tripped in the same manner as in the thermal tripping operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side sectional view of a circuit breaker embodying principles of this invention with the breaker being shown in the closed position;

FIG. 2 is a view similar to FIG. 1 with the breaker being shown in the reset position;

FIG. 3 is a view similar to FIGS. 1 and 2 with the breaker being shown in a tripped-open position following a thermal tripping operation;

FIG. 4 is a view similar to FIGS. 13 with the breaker being shown in a tripped open position reached during a thermal tripping operation;

FIG. 5 is a partial view taken along the line V-V of FIG. 1;

FIG. 6 is a side sectional view of a circuit breake illustrating another embodiment of the invention with the circuit breaker being shown in the closed position;

FIG.7 is a view similar to FIG. 6 with the breaker being shown in the reset position;

FIG. 8 is a view similar to FIGS. 6 and 7 with the breaker being shown in a tripped-open position following a thermal tripping operation; and

FIG. 9 is a view similar to FIGS. 6-8 with the breaker being shown in a tripped-open position following an electromagnetic tripping operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 of the drawings, there is shown therein a two-pole circuit breaker 9 of the type that is described in more detail in the above-mentioned patent to Leonard et a1. Pat. No. 2,686,242. The circuit breaker 9 comprises an insulating base or housing member 11 on which are mounted the parts of the breaker mechanism. The breaker mechanism comprises a stationary contact 13, a movable contact 15, an operating mechanism indicated generally at 17 and a trip device indicated generally at 19. A spring 23 provides contact pressure in the closed position of the contacts.

The movable contact is fixedly mounted on one end of an elongated contact arm structure 25 that is latched, at the other end 27 thereof, in the operating position seen in FIG. 1 by means of an elongated primary latch member 29. The contact arm structure 25 comprises an elongated arm portion 31 and a U-shaped member 33 that carries the contact and that is mounted on the portion 31, by means of a pivot pin 35, for limited movement relative to the arm portion 31 to provide contact alignment in the closed-contact position. The movable contact 15 is fixedly mounted on the U-shaped member 33. The contact arm structure is supported at 27 on a latch surface 37 of the primary latch 29, and the contact arm 25 pivots on the latch surface 37, during manual operation of the circuit breaker in a manner to be hereinafter described. A tension spring 39 is connected at one end thereof to an extension 41 of the contact arm structure 25, and at the other end thereof to a stationary spring support pin 43. The contact arm structure 25 is pivotally connected, intermediate the ends thereof, to an operating link 45 by means of a pivot pin 47. A pair of operating springs 49 (only one of which is seen in FIG. 1) are connected at one end to a pin 51 on the upper end of the operating link 45 and at the other end to an insulating operating handle 53. The operating link 45 comprises twin members connected by means of the pin 51. A roller 55 is mounted on the pin 47 between the twin members of the link 45 and a roller 57 is mounted on the pin 51 between the twin members of the link 45. The rollers 55, 57 are positioned in a generally triangular shaped opening 59 in the insulating base 11, and they engage the surfaces defining the opening 59 to guide movement of the operating link 45 in a manner to be hereinafter described.

, The insulating handle 53, which is biased inward 'by means of the tension springs .49, rides on an arcuate sur face 61 which guides the handle 53 for movement between the on and off" positions.

In the closed position of the circuit breaker (FIG. 1) the line of action of the operating springs 49 is below the center indicated at A about which the handle 53 moves so that the springs 49 bias the handle to the on position. The line of action of the springs 49 is also below the center indicated at B about which the roller 57 travels on the surface 59 so that the roller 57 is biased to the right in the opening 59 to:maintain the operating link 45 in theclosed position seen in FIG. '1'. When the operating handle 53 is moved from the on position seen in full lines to the off position seen in broken lines',"th'e line of action oflthe operating springs 49 moves to the left over the center line B-57. When'this occurs, a component of the force of the springs49 biases the roller 57 causing the roller, together with the link 45, to move from the closed position seen in full lines to the open position i seen in broken lines to'pivot the movable contact arm structure 25 about the latch surface 37 from the closed position seen in full linesto the open position seen in broken lines. This movement of the operating link and movable contact arm structure 25 occurs with a ."snap action.

The breaker is closed 'by' reverse'movernent of the handle 53 from the off position tothe on position. During this movement, the line of action of the operating springs 49 crosses over the center line B-'57 whereupon the springs 49 bias the roller 57 to the right to move the operating link 45 and movable contact arm structure 25 to the closed position with a snap-action.

Referring to FIG. 1, it will be seen that in the closed position of the cricuit breaker, the circuit extends from a conductor 65 through a conductor 21, the stationary contact 13, the movable contact 15, the member 33, flexible conductors 67 that are connected at one end to the member 33 and at the other end to a conductor 69, the conductor 69, a bimetal 71 that is connected at one end to the conductor 69 and at the other end to a conductor 73, the conductor 73 to a flexible conductor 75 that is connected to the conductor 73. The bimetal 71 is fixedly secured at the lower end thereof to the conductor 73 that is suitably fixedly secured to the housing 11. A latch member 77, which is fixedly secured at one end thereof to the free end of the bimetal 71, latches a secondary latch member 79 that is pivotally mounted on a stationary pivot 81 and that is biased in a clockwise (FIG. 1) .direction by means of a tension spring 83. I

When a persistent relatively low overload current above a first predetermined value occurs in the circuit through the breaker, the bimetal 71 becomes heated and flexes, with a time delay, to the left (FIG. 1) whereuponthe latch 77 releases the secondary latch member'79. Upon release of the secondary latch member 79, the spring 83 snaps the secondary latch member 79 clockwise about the pivot 81 causing a projection 85 on the secondary latch member 79 to engage the uppere'nd 87 of the primary latch member 29 to pivot the primary latch member 29 in a counterclockwise direction about the fixed pivot 30, against the bias of a torsion spring 89. This movement moves the latch surface 37 to release the latched end 27 of the contact arm 25 whereupon the tension spring 39 moves the contact arm 25 about the pivot 47 to the tripped-open position seen in FIG. 3 with a snap-action. i p p l The mechanism is reset and relatched following an automatic opening operation by moving thehandle 53 to a position slightly past the -off,position. During this movement with the upper part of the-one end ofthe contact arm engaging a surface 91 on the insulating housing 11, when the operating link 45 is moved to the position seen in FIG. 2, the latching end 27 of the contact arm 25 is moved up over the latch surface .37 of the primary latch member 29, and as the handle 53 approaches the position seen in FIG. 2, a projection 93 thereon engages the secondary latch member 79 to rotate the secondary latch member 79 counterclockwise about the pivot 81 where the latch member 79 is again relatched by the latch 77. When the secondary latch member 79 is moved to the relatched position, the projection 85 moves away from the upper end 87 of the primary latch member 29, and the torsion spring 89 returns the primary latch member 29 to the latching position seen in FIG. 2 to relatch the contact arm 25 in the operating position. The movement of the primary latch member 29 to the latching po sition is stopped when the upper end of the primary latch member 29 engages a projection 97 on the base 11. The reset circuit breaker (FIG. 2) may then be operated in the same manner as was hereinbefore described.

In addition to the bimetal or thermal trip 71, the trip means 19 comprises an electromagnetic trip 101. As will be understood with reference to FIGS. 1 and 5, the electromagnetic trip 101 comprises an insulating support 103 that is fixedly secured to the insulating housing 11 by suitable securing means. A U-shaped laminated core 105 is fixedly secured to the support 103 by means of a pair of rivets 107. The core 105 is provided with a V-shaped slot 109 in one leg thereof, An armature structure 113, comprising an armature 115 and an elongated rod 117 pivotally connected to the armature 115 by means of a pin 119, is supported on one leg of the U-shaped core 105. The laminated armature 115 is provided with a knife-edge pivot 121 that fits in the slot 109 to pivotally support the armature 115 on the one leg of the core 105. A pair of tension springs 123 are provided to bias the armature 115 in a counterclockwise (FIG. 5) direction, which movement is limited by the engagement of the armature 115 with an adjusting screw 125 that is threadedly supported on a fixed support 127. The rod 117 eX- tends through an opening in an insulating extension 129 that is fixedly supported on one end of the primary latch 29. A pair of adjusting nuts 131 are threadedly supported on the upper end of the rod 117. As can be understood with reference to FIG. 1, the conductor 65 is a generally rigid conductor that extends through an opening or slot 135 in the insulating base 111 with the slot 135 limiting lateral movement of the conductor 65. The conductor 65 (FIG. 5) extends between the legs of the U-shaped core 105 to energize the

electromagnet

105, 115.

Upon the occurrence of a severe overload or short circuit above a second predetermined value higher than the above-mentioned first predetermined value, the conductor 65 energizes the

electromagnet

105, 115 sufficient- 1y to cause attraction of the armature 115 whereupon the armature 115 pivots on the one leg of the core 105-toward the other leg of the core 105 moving the rod 117 toward the core 105 whereupon the nuts 131 engage the extension 129 of the primary latch 29 to move the primary latch 29 in a counterclockwise (FIG. 1) direction to the releasing position to release the contact arm structure 25. Upon release of the contact arm structure 25 the spring 39 moves the contact arm to the tripped-open position seen in FIG. 4 in the same manner as was hereinbefore described with regard to the thermal tripping operation. As can be seen in FIG. 4, the armature is in the attracted position to show movement of the primary latch 29 to the tripped position. It can be understood that when the circuit is open the springs 123 will return the armature structure to the unattracted position seen in FIG. 1. Following an electromagnetic tripping operation, the contact arm 25 is reset by movement of the handle 53 to a position slightly past the oif position during which movement the operating link 45 is moved to the position seen in FIG. 2, and with the upper end of the contact arm 25 engaging the projection 91, the contact arm structure 25 is moved to the position seen in FIG. 2 whereupon the torsion spring 89 biases the latch 29 to the latched position so that the latch surface 37 engages the latch end 27 of the contact arm structure 25 to relatch the contact arm 25 in the operating position seen in FIG. 2. Thereafter the circuit breaker can be manually operated in the same manner as was hereinbefore described. It can be understood that although in the thermal tripping operation the secondary latch 79 was first released to strike the primary latch 29 to efiect unlatching movement of the primary latch 29, during an instantaneous electromagnetic tripping operation the armature structure 113 directly strikes the primary latch 29 to move the primary latch 29 to the unlatching position.

As can be understood with reference to FIGS. 1 and 5, the circuit breaker 9 is a two-pole circuit breaker with each pole operating in the manner hereinbefore described with reference to the drawings. For a description of the means for tying the poles together for simultaneous operation, the reader is referred to the above-mentioned patent to Leonard et al. No. 2,686,242.

Another embodiment of the invention is disclosed in FIGS. 6-9. Referring to FIG. 6, a circuit breaker indicated generally at 141 is of the type that is more specifically described in the above-mentioned patent to Hodnette et al. Pat. No. 2,586,429. The circuit breaker 141 comprises an insulating base 143 and a metal cover 145 suitably secured to the base 143. A circuit-breaker structure or mechanism, comprising an operating mechanism 147 and a trip device 149, is suitably mounted in the

housing

143, 145.

The circuit breaker mechanism comprises a main stationary contact 151 that is mounted on a conducting plate 153 and another stationary contact 155 that is mounted on a conducting plate 157. An elongated movable contact arm structure, indicated generally at 159, comprises a first arm portion 161 having a movable contact 163 thereon and a second portion 165 having a movable contact 167 thereon. Both of the

contact arm portions

161 and 165 are pivotally mounted on a pin 171 that is supported on a fixed bracket 173 that is suitably mounted on the base 143. A spring member 175 biases the contact 151 into engagement with the contact 163 to provide contact pressure in the closed position between the

contacts

151, 163. A spring 177 is positioned between a portion of the contact arm portion 161 and the contact arm portion 165 to provide contact pressure between the

contacts

155, 167 in the closed position of the contacts. The contact arm portion 161 is pivotally connected to a toggle link 181 by means of a pivot pin 183. The pivot pin 183 also passes through an elongated slot in the contact arm portion 165 to connect the contact arm portion 165 to the link 181 with the contact arm portion 165 being movable, within the limits of the slot, relative to the contact arm portion 161 and the link 181 so that in the closed position of the contacts the spring 177 can bias the contact 167 against the contact 155. The toggle link 181 is connected to an upper toggle link 185 by means of a pivot pin 187. The upper toggle link 185 is pivotally connected to a releasable trip member 189 by means of a pivot pin 191. The releasable trip member 189 is mounted for pivotal movement on a fixed pivot pin 193. The releasable trip member 189 is latched in the position shown in FIG. 6 by means of a primary latch member with the latched end of the trip member 189 being latched in a windowopening of the member 195. The releasable trip member, 189 is biased in a clockwise direction by means of a compression spring 199 that engages a fixed pin 201 and a movable carrier 203 that is connected to the releasable trip member 189 by means of a pivot pin 204.

A hook-type actuator 205 is mounted on a fixed pivot 207. As can be seen in FIG. 6, in the closed position of the contacts, the hooked end of the actuating member 205 engages the knee pivot 187 of the

toggle

181, 185 to hold the toggle in a slightly underset position to thereby hold the contact arm structure 159 in the closed position seen in FIG. 6. A pair of overcenter springs 209 are provided for operating the circuit breaker. The springs 209 are tension springs connected at one end to the actuating lever 205 and at the other end to an operating rod 213. The operating rod '213 is guided for movement between the on and" otf positions in a slot 215 in a pair of stationary supporting frames 217. An operating lever 221, comprising a pair of spaced legs that straddle the rod 213, is fixed to a rod 223 that is mounted on the plates 217 for movement about a fixed pivot. The rod 223 extends outside of the

housing

143, 145 and is provided with a crank-arm or handle for rotating the rod to operate the circuit breaker. The handle structure is disclosed in the above-mentioned patent to Hodnette et al. Patent No. 2,586,429; i

The circuit breaker is manually operated from the on position to the otf position by manual rotation of the rod or shaft 223 tomove the operating lever 221 counterclockwise. During this movement, the-rod 213 is moved in the opening 215 to move the springs 209 overcenter past thepivot 2070f the actuator 205 to thereby move the actuator 205 clockwise about the pivot 207. With the knee pivot 187 engaged in the hook portion of the actuator 205, this movement moves the 'link 185 about the pivot 191 (in this position the pivot of the link 187 and the pivot of the actuator 205 are in axial alignment) to thereby move the upper toggle link 185 clockwise to collapse the

toggle

181, 185 to move the contact arm structure 159 about the pivot 171 to the open position.

The circuit breaker is closed by rotating the rod or shaft 223 clockwise to thereby move the operating lever 221 clockwise to the position seen in FIG. 6. This movement moves the upper end of the springs 209 to move the line of action of the springs 209 overcenter whereupon the actuator 205 is moved counterclockwise to operate against the knee pivot 187 to erect the toggle to thereby move the contact arm structure 159 clockwise to the closed position seen in FIG. 6. The overcenter springs 209 operate to open and close the contact arm structure 159 with a snap-action.

Referring to FIG. 6, in the closed position of the contacts, a circuit extends from a conductor 227 through the conductor 157, a flexible conductor 229, the conductor 153, the stationary contact 155, the movable contact 163, the contact arm portion 161, a flexible conductor 231, to a rigid conductor 233 that is fixed to the contact arm portion 165 at the end of the contact arm portion 165. A parallel current path extendsfrom the conductor 157 through the stationary contact 155, movable contact .167, and contact arm portion 165 to the rigid conductor 233. The current extends from the rigid conductor 233 through a flexible conductor 235, a conducting support 237 that is fixed to the housing base 143, a bimetal 239 that is fixedly connected at the lower end thereof to the conducting support 237, a conducting tab 241 that is secured to the upper or free end of the bimetal 239, to a flexible conductor 243 that is secured to the conducting tab 241. A latch 245, which is fixed to the free'end of the bimetal 239, engages a secondary latch member 247 to latch the member 247 in the position seen in FIG. 6. The secondary latch member 247 is mounted for pivotal movement about a fixed axis 249, and a tension spring 251, which is connected at one end thereof, to the secondary latch 247 and at the other end thereof to a spring support 253, biases the secondary latch 247 in a clockwise (FIG. 6) direction.

With the circuit breaker in the closed position seen in FIG. 6, upon the occurrence of a persistent relatively low overload above a first predetermined value, the bimetal 239 becomes heated and flexes to the left with a time delay to move the latch 245 to the left to release the secondary latch 247. Upon release of the secondary latch 247, the spring 257 moves the secondary latch 247 clockwise whereupon an extension 257 on the secondary latch 247 strikes the upper end of the primary latch 195 to move the primary latch 195 to the releasing position. The primary latch 195 is a member of magnetic material that is secured to a pin 261 that is pivotally mounted on the 8 side plates 217. A tension spring 263 biases the primary latch 195 in a clockwise (FIG. 6) direction to the latching position shown in FIG. 6. Upon tripping movement of the secondary latch 247, the extension 257 engages the primary latch 195 to pivot the primary latch 195 counterclockwise whereupon the releasable trip member 189 is freed from the latching position in the window opening of the primary latch 195. Upon release of the releasable trip member 189, the spring 199 pivots the releasable trip member 189 in a clockwise direction. During the early portion of this movement of the releasable member 189 the knee pivot 187 of the

toggle

181, 185 moves out of the hook portion of the actuator 205 and shortly thereafter the end of the spring carrier 203 strikes the upper toggle link 187. This action causes collapse of the toggle 181, to effect opening movement of the contact arm structure 159 from the position seen in FIG. 6 to the tripped-open position seen in FIG. 8.

During the tripping operation the knee pivot 187 of the toggle escapes from the actuator 205, and before the breaker can be reclosed, it is necessary to reengage'the actuator 205 within the knee pivot 187 and to also reset and relatch the releasable trip member 189. Both of these operations are accomplished by moving the rod 223 to move the operating lever 221 and the rod 213 from the position seen in FIG. 8 to the position seen in FIG. 7. During this movement, the rod '213 carries the line of action of the springs 209 over-center above thepivot 207 of the actuator 205 whereupon the springs 209 actuate the actuator 205 in a clockwise direction to reengage the hook portion of the actuator 205 with the knee pivot 187. During this movement, the rod 213 engages a portion 267 of the releasable trip member 189 to rotate the trip member 189 counterclockwise about the pivot 193. Near the end of this movement, of the trip member 189, the latching end thereof wipes by the upper portion of the primary latch 195, and the spring 263 biases the primary latch clockwise when the latching end of the trip member 189 reaches the window-opening of the member 195 to thereby relatch the trip member 189 in the position seen in FIG. 7. Clockwise or latching movement of the primary latch 195 is limited by engagement thereof with a suitable stop on the frame 217. During this resetting movement, the rod 213 engages a surface 271 in an opening in a resetting lever 273 which is supported for pivotal movement on the pin 193. This movement moves the resetting lever 273 counterclockwise, and a part 275 thereof engages the secondary latch 247 to pivot the secondary latch 247 counterclockwise to the reset position seen in FIG. 7 in which position the secondary latch 247 is again latched by the latch 245. With the parts reset in the position as shown in FIG. 7, the circuit breaker is in readiness for operation in the same manner as was hereinbefore described. During the next movement to the closed position, the rod 213 engages the trip resetting member 273 to pivot the resetting member 273 clockwise to the position seen in FIG. 6.

As can be seen in FIG. 6, the primary latch 195 is formed to extend down toward the rigid conductor 233. The primary latch is bent over to provide an armature portion 279 that is adjacent the conductor 233. The primary latch 195, including the armature portion 279, is of magnetic material. When a severe overload or short circuit above a second predetermined value higher than the above-mentioned first predetermined value occurs, the magnetic flux around the conductor 233 attracts the armature portion 279 to instantaneously move the primary latch 195 in a counterclockwise direction about the pivot 261 to release the trip member 189 whereupon the circuit breaker is tripped open in the same manner as was hereinbefore described with regard to the thermal tripping operation. When the circuit is interrupted, the spring 263 biases the primary latch 195 to the position seen in FIG. 9. The parts are shown in FIG. 9 in the tripped-open position reached following an electromagnetic tripping operation. As can be seen in FIG. 9, the secondary latch 247 is still retained in the latching position by means of the latch 245. Following an electromagnetic tripping operation, the circuit breaker is reset in the same manner as was hereinbefore described except that the secondary latch 247, which has not been unlatched, need not be moved to the latching position during this resetting operation; When the parts are moved to the reset position, the releasable member 189 engages the primary latch 195 to move past the upper portion of the primary latch 195 and when the latching window is adjacent the latching end of the releasable member 189, the spring 263 biases the primary latch 195 clockwise to again latch the releasable member 189. Thereafter, the circuit breaker can be operated in the same manner as was hereinbefore described.

Although the electromagnetic tripped-open positions of both of the above-described embodiments were disclosed with the secondary latch still in the latched position, it can be understood that the overload could beat the bimetal sufificiently, in both embodiments, to cause the bimetal to flex to release the secondary latch; but it is' to be noted that the electromagnetic trip is instantaneous and the secondary latch, in these cases, would be released after the circuit breaker has been tripped.

I claim as my invention:

, 1. A circuit breaker comprising a stationary contact, a movable contact, a movable contact arm carrying said movable contact, a primary latch member in a latching position latching said movable contact arm in an operating position, said primary latch member-being supported for movement on a support separate from said movable contact arm, a spring operating mechanism manually operable to an open position to move said latched movable contact arm to an open position with a snap action, said spring operating mechanism being manually operable to a closed position to move said latched movable contact arm to a closed position with a snap action, trip means comprisinga thermal trip operating with a time delay upon the occurrence of a sustained overload above a 'first predetermined value to unlatch said movable contact arm, said trip means comprising an electromagnetic trip operating instantaneously upon the occurrence of an overload above a secondpredetermined value to unlatch said movable contact arm, and means operating when said movable contact arm is unlatched to move said movable contact arm to an open position.

2. A-circuit breaker according to claim 1, said firstmentioned open position of said movable contact arm being a'manually-open position with said movable contact arm being latched,-said second-mentioned open position being a tripped-open position with said movable contact arm being unlatched, and said operating mechanism being operablewhen said movable contact arm is in said tripped-open position to move said movable contact arm to relatch said movable contact arm to prepare said circuit breaker for manual operation.

3. A circuit breaker according to claim 1, said primary latch member comprising an elaborated latch member supported intermediate the ends thereof for pivotal movement about a fixed pivot, said thermal trip effecting operation against one end of said elongated primary latch member to move said primary latch member to the unlatching position upon the occurrence of a thermal tripping operation, and said electromagnetic trip operating against the opposite end of said elongated 'primarylatch member to move said elongatedprimary latch member to the unlatching position upon the occurrence of an electromagnetic trip ping operation.

4. A circuit breaker according to claim 1, said movable contact arm comprising an elongated arm structure carry in'g said movable contact at one end thereof and being latched at the other end thereof by said primary latch member, said operating mechanism being pivotally connected to said elongated contact arm intermediate the ends of said elongated contact arm, during said manual operations said operating mechanism operating to pivot said elongated contact arm about said other end on said primary latch member between the open and closed positions, during said thermal and electromagnetic tripping operations said primary latch member being moved to an unlatching position to unlatch said other end of said elongated contact arm whereupon said elongated contact arm is pivoted about the intermediate pivot thereof to a tripped-open position.

5. A circuit breaker according to claim 4, said primary latch comprising an elongated latch member supported intermediate the ends thereof for movement about a fixed pivot, said operating mechanism comprising a first spring means operable during said manual operations to move said elongated contact arm about said other end thereof between the open and closed positions, a second spring means biasing said other end of said elongated contact arm into latching engagement with said primary latch, a secondary latch member supported for movement about a fixed pivot in proximity to one end of said primary latch member, a third spring means biasing said secondary latch member toward a tripping position, said thermal trip comprising a bimetal in an initial position to latch said secondary latch member, upon the occurrence of said thermal tripping operation said bimetal flexing to release said secondary latch member whereupon said third spring means biases said secondary latch member against said one end of said primary latch member to pivot said primary latch member to the unlatching posi: tion whereupon said second spring means operates to pivot said movable contact arm about the intermediate pivot thereof to the tripped-open position, said electromagnetic trip comprising a core member and an armature structure supported to cooperate with said core member, said armature structure being positioned to engage the opposite end of said primary latch member, and upon the occurrence of an electromagnetic tripping operation said armature structure being attracted toward said core member to engage said opposite end of said primary latch member to pivot said primary latch member about the intermediate pivot thereof to an unlatching position whereupon said second spring means operates to pivot said movable contact arm about the intermediate pivot thereof to the tripped-open position.

6. A circuit breaker comprising a stationary contact, a movable contact, an elongated movable contact arm carrying said movable contact at one end thereof, an elongated primary latch member pivotally supported on a fixed pivot intermediate the ends thereof and latching the other end of said elongated contact arm, an operating mechanism manually operable to an open position to move said movable contact arm about'said other end to an open position, said operating mechanism beingmanually operable to a closed position to move said movable contact arm about said other end to the closed position, a secondary latch member, trip means comprising a bimetal in an initial position latching said secondary latch member in a latched position, upon the occurrence of a sustained overload above a first predetermined value said bimetal member flexing to release said secondary latch member and said secondary latch member moving to engage said primary latch member on a first side of the pivot of said primary latch member to pivot said primary latch member to an unlatching position, said trip means comprising an electromagnetic trip, said electromagnetic trip comprising a magnetic core and an armature structure supported to cooperate with said magnetic core, upon the occurrence of an overload above a second predetermined value said armature structure being attracted toward said core and moving to engage said primary latch member on the opposite side of the pivot of said primary latch member to pivot said primary latch member to the unlatching position, trip-spring means, and upon pivotal movement of said primary latch member to the unlatching position said trip-spring means operating to pivot said movable contact arm about the intermediate pivot thereof to a tripped-open position.

7. A circuit breaker according to claim 6, said operating mechanism comprising an overcenter tension-spring operating mechanism manually operable between overcenter positions to open and close said latched movable contact arm with a snap action, and said trip-spring means comprising a tension spring operable when said primary latch is moved to the unlatched position to pivot said elongated contact arm to the tripped-open position.

8. A circuit breaker comprising a stationary contact, a movable contact, an elongated contact arm carrying said movable contact at one end thereof, a primary latch member latching the other end of said movable contact arm, an operating mechanism comprising an operating link, means pivotally connecting said movable contact arm intermediate the ends thereof to said operating link, an operating member, an operating spring connected between said operating member and said operating link, said operating member being manually operable to an open position to operate through said operating spring and operating link to move said latched movable contact arm about said other end to a manually open position, said operating member being manually operable to a closed position to operate through said operating spring and operating link to move said latched movable contact arm about said other end to a manually closed position, trip means comprising a thermal trip operating with a time delay upon the occurrence of a sustained overload above a first predetermined value to move said primary latch member to an unlatching position to unlatch said other end of said movable contact arm, said trip means comprising an electromagnetic trip operable instantaneously upon the occurrence of an overload above a second predetermined value to move said primary latch member to said unlatching position to unlatch said other end of said movable contact arm, and trip-spring means operating when said movable contact arm is unlatched to move said movable contact arm about the intermediate pivot thereof to a tripped-open position.

9. A circuit breaker according to claim 8, said primary latch member comprising an elongated latch member supported for pivotal movement about a fixed pivot intermediate the ends thereof, a secondary latch member, said thermal trip comprising a bimetal in an initial position to efiect latching of said secondary latch member, upon the occurrence of said overload above said first predetermined value said bimetal flexing to unlatch said secondary latch member and said secondary latch member moving to operate against said primary latch member on a first side of the pivot of said primary latch member to move said primary latch member to the unlatching position, said electromagnetic trip comprising a core and an armature structure supported to cooperate with said core, upon the occurrence of an overload above said second predetermined value said armature structure being attracted to said core to operate against said primary latch member on the opposite side of the pivot of said primary latch member to move said primary latch member to the unlatching position.

10. A circuit breaker for controlling an electric circuit, said circuit breaker comprising a stationary contact, a movable contact, a movable contact arm carrying said movable contact, a trip member, a primary latch supported in a latching position and latching said trip member, said trip member being releasable to effect automatic opening of said contacts, a secondary latch separate from said primary latch, a bimetal in an initial position to latch said secondary latch in a latched position, upon the occurrence of an overload in said circuit above a first predetermined value said bimetal flexing to release said secondary latch whereupon said secondary latch moves to strike said primary latch to efiiect release of said releasable member, said primary latch comprising an armature portion movable as a unit with said primary latch, said armature portion being positioned to be magnetically energized by the current in said circuit, and upon the occurrence of an overload in said circuit above a second predetermined value said armature portion being energized sufficiently to move said primary latch to effect release of said releasable member.

11. A circuit breaker according to claim 10, said primary latch being supported for pivotal movement intermediate the ends thereof, upon the occurrence of said overload above said first predetermined value when said secondary latch is released said secondary latch striking said primary latch on a first side of said pivot, and said armature portion being positioned on the side of said pivot opposite said first side.

12. A circuit breaker according to claim 11, said mova ble contact arm structure comprising an elongated movable contact arm structure supported for movement about a fixed pivot and carrying said movable contact on a first side of said fixed pivot, a rigid conductor moving with said movable contact arm on the side of said pivot opposite the first side, and said armature portion being positioned adjacent said rigid conductor to be attracted to said rigid conductor portion upon the occurrence of said overload above said second predetermined value.

13. A circuit breaker comprising a stationary contact, a movable contact, an elongated movable contact arm structure supported for movement about a fixed pivot and carrying said movable contact on a first side of said fixed pivot, an operating mechanism comprising a toggle and an overcenter tension spring means connected to operate said toggle, said circuit breaker comprising a trip member and a primary latch member in a latching position latching said trip member, with said trip member latched said operating mechanism being manually movable to an open position to operate said tension spring means overcenter to cause collapse, of said toggle to pivot said movable contact arm structure to an open position, with said trip member in the latched position, said operating mechanism being manually operable to operate said overcenter tension spring means overcenter to a closed position to cause erection of said t ggle to pivot said movable contact arm structure to a closed position, a secondary latch supported on a fixed pivot spaced from said primary latch, secondary spring means biasing said secondary latch toward a tripped position, a thermal trip comprising a bimetal supported in an initial position to eifect latching of said secondary latch, trip-spring means, upon the occurrence of an overload above a first predetermined value said bimetal flexing to release said secondary latch whereupon said secondary spring means operates to move said secondary latch such that said secondary latch strikes said primary latch to release said tripmember, upon release of said trip member said trip-spring means operating to collapse said toggle to move said contact arm structure to an open position, said primary latch comprising an armature portion movable as a unit with said primary latch, upon the occurrence of an overload above a second predetermined value said armature portion moving instantaneously to move said primary latch to effect release of said trip member.

14. A circuit breaker according to claim 13, said primary latch comprising an elongated latch member supported intermediate the ends thereof for movement about a fixed pivot, upon release of said secondary latch said secondary latch striking said primary latch on a first side of the pivot of said primary latch, said armature portion being positioned on a second side of the pivot of said primary latch opposite said first side.

15. A circuit breaker according to claim 14, said elongated movable contact arm structure comprising a rigid conductor on the side of the pivot of said movable contact arm structure that is opposite the side that carries said movable contact, and said armature portion being positioned in proximity to said rigid conductor to be magnetically energized by the current flow in said rigid con- 13 ductor and to move toward said rigid conductor to effect movement of said primary latch to release said trip member upon the occurrence of an overload above said second predetermined value.

References Cited UNITED STATES PATENTS 14 2,686,242 8/1954 Leonard 337--47 2,783,330 2/1957 Casey 33771 3,263,045 7/ 1966 Beaudoin 33535 B. A. GILHEANY, Primary Examiner H. BROOME, Assistant Examiner US. Cl. X.R. 335-173