US3530414A

US3530414A - Circuit breaker with improved trip means

Info

Publication number: US3530414A
Application number: US802430A
Authority: US
Inventors: Howard A Wagner
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1969-02-26
Filing date: 1969-02-26
Publication date: 1970-09-22
Anticipated expiration: 1987-09-22
Also published as: GB1231165A; BR7017048D0; FR2033397A1; FR2033397B1; JPS4934424B1

Description

Sept. 22, 1970 H. A WAGNER CIRCUIT BREAKER WITH IMPROVED TRIP MEANS 4 Sheets-Sheet 1 Filed Feb. 26, 1969 Sept. 22, 1970 H. A. WAGNER CIRCUIT BREAKER WITH IMPROVED TRIP MEANS Filed Feb. 26, 1969 4 Sheets-Sheet 2 p 1970 H. A WAGNER 3,530,414

CIRCUIT BREAKER WITH IMPROVED TRIP MEANS Filed Feb. 26, 1969 4 Sheets-Sheet {5 Sept. 22, 1970 WAGNER 3,530,414

CIRCUIT BREAKER WITH IMPROVED TRIP MEANS Filed Feb. 26, 1969 4 Sheets-Sheet 4 FIGS.

FIG.4.

ris

United States Patent US. Cl. 335174 Claims ABSTRACT OF THE DISCLOSURE A circuit breaker comprises a trip actuator comprising an armature structure and permanent magnet means supplying magnetic flux that operates through a magnetic supporting frame to maintain the armature structure in an initial non-tripping position. When released, the armature structure moves to a tripping position and, at one end thereof, actuates the breaker latch and trip device to trip the breaker. As the breaker opens, the operating mechanism operates against a pivotally supported lever, that is resiliently connected to the other end of the armature structure, to automatically reset the armature structure in the initial position.

CROSS-REFERENCES TO RELATED APPLICATIONS Circuit breakers, having trip actuators of the general type herein disclosed, are disclosed in the applications of Edmund W. Kuhn, Ser. No. 770,305, filed Oct. 24, 1968 and Nagar Patel, Ser. No. 770,236, filed Oct. 24, 1968.

BACKGROUND OF THE INVENTION Field of the invention Circuit breakers of the type comprising a trip device and a permanent-magnet type trip actuator operable to actuate the trip device in order to trip the circuit breaker.

Description of the prior art In the above-mentioned applications of Edmund W. Kuhn and Nagar Patel, there are disclosed circuit breakers having trip actuators of the type comprising an armature structure releasable to trip the breaker and permanent-magnet means operating to maintain the armature structure in an initial non-tripping position.

SUMMARY OF THE INVENTION An improved circuit breaker comprises cooperable contacts, an operating mechanism releasable to effect automatic opening of the contacts and a permanent-magnet type trip actuator operable to release the operating mechanism. The trip actuator comprises permanent magnet means that supplies magnetic flux which operates through an armature and a magnetic supporting frame to main tain an armature structure in an initial non-tripping position. The armataure structure, which is spring biased toward a tripping position, comprises the armature and an elongated non-magnetic support rod that extends from opposite sides of the trip device to support the armature structure for rectilinear reciprocal movement. The trip actuator comprises coil means that is pulsed with a DC current to buck the magnetic flux whereupon the spring means biases the armature structure from the initial position to an actuating or tripping position during which movement the armature structure, at one end thereof, operates the trip device to the tripping position to effect opening of the breaker. The armature structure, at the other end thereof is connected to one end of a pivotally supported lever by means of a resilient connector. When the contacts of the circuit breaker open -a part that moves with a contact arm operates against the other end of the lever to pivot the lever which pulls the armature structure to the reset initial position. With the resilient or spring connection between the pivoted lever and armature structure, the construction and positioning of parts is less critical in that the resilient connector can permit some additional movement of the pivoted lever after the armature structure reaches the reset position. The improved trip actuator is reliable in operation and relatively easy to manufacture and assemble into operating relationship with the parts of the circuit breaker.

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

FIG. 2 is a sectional view, with parts broken away, taken generally along the line II-II of FIG. 1;

FIG. 3 is a sectional view, with parts broken away, taken generally along the line IIIIII of FIG. 1;

FIG. 4 is a sectional view of the trip actuator taken generally along the line IV-IV of FIG. 5;

FIG. 5 is a sectional view taken generally along the line VV of FIG. 4;

FIG. 6 is a view similar to FIG. 5 with the armature structure being shown in the actuating or tripping position; and

FIG. 7 is a partial view illustrating another embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, there is disclosed, in FIGS. 1-3, a circuit breaker 3 comprising an insulating housing 5 and a circuit-breaker mechanism 7 supported within the housing. The housing 5 comprises an insulating base 9 and an insulating cover 11 mounted on the base 9.

The circuit-breaker mechanism 7 comprises an operating mechanism 13, a latch and trip device 15 and a trip actuator 16. Except for the latch and trip device 15 and trip actuator 16, the circuit breaker 3 is of the type that is more specifically described in the patent to Albert R. Cellerini et 211., Pat. No. 3,287,534 issued Nov. 22, 1966. The circuit breaker 3 is a three-pole circuit breaker comprising three compartments disposed in a side-by-side relationship. The center pole compartment (FIG. 2) is separated from the two outer pole compartments by insulating barrier means formed with the housing base 9 and cover 11. The operating mechanism 13, that is disposed in the center pole compartment, is a single operating mechanism for operating the contacts of all three pole units.

Each pole unit comprises a stationary contact 21 that is fixedly secured to a rigid main conductor 23 that is secured to the base 9 by means of bolts 25. In each pole unit, a movable contact 27 is welded or brazed to a contact arm 29 that is pivotally mounted on a switch arm 31 by means of a pivot pin 33. Each of the switch arms 33 is pivotally supported at one end thereof on a support bracket 34 by means of a pivot pin 35. The switch arms 31 for all three of the pole units are connected, to move in unison, by means of a common insulating tie bar 37 that is rigidly connected to all three of the switch arms. Each of the contact arms 29 is biased about the associated pivot 33 by means of a spring 39 to provide contact pressure in the closed position.

The switch arms 31 are operated to the open and closed positions by means of the operating mechanism 13 (FIG. 2). The operating mechanism 13 comprises a toggle link 41 that is pivotally connected to an extension 43 of the center-pole switch arm 31 by means of a pivot 3 pin 45. The toggle link 41 is pivotally connected to another toggle link 47 by means of a knee pivot pin 49. The upper end of the toggle link 47 is pivotally connected to a cradle or releasable member 51 by means of a pivot pin 53. The releasable member 51 is pivotally supported at one end thereof on the supporting bracket 34 by means of a pivot pin 57. The other end 59 of the releasable member 51 is held in a latched position by means of a latch structure 61. The operating mechanism 13 also comprises a generally U-shaped operating lever 63 that is pivotally supported on the bracket 34 by means of pins 65 that engage the inner ends of the legs of the operating lever 63. An insulating shield 67, that substantially closes an opening 69 in the cover 11, is secured to the upper end of the operating lever 63. The shield 67 has an integral insulating handle portion 71 that extends out through the opening 69 to permit manual operation of the breaker. Two overcenter springs 75 (only one being shown in FIG. 1) are connected under tension between the knee pin 49 of the toggle 41, 47 and the upper end of the operating lever 63.

In each pole unit, an arc-extinguishing unit 81 is provided to extinguish the arcs drawn between the associated contacts 21, 27. Each arc-extinguishing unit comprises an insulating housing 83 and a plurality of magnetic steel plates 85 (FIG. 1) supported within the housing 83. The moving contact 27 moves within a generally V-shaped opening 87 (FIG. 1) in the stacked plates 85, and the are drawn between the contacts 21, 27 is magnetically moved to the right (FIGS. 1-3) into the plates 85 to be extinguished during circuit interruption. Each of the arc-extinguishing units 81 is secured to the associated main conductor 23 (FIGS. 1-3) by means of four bolts 89 that are threaded into tapped openings in the conductor 23.

For each pole unit, the circuit breaker 3 is provided with two rear-type terminal connectors 91 that are secured to flat undersurfaces of

internal conductors

23, 93 by bolt means 95. As can be seen in FIGS. 2 and 3, the terminal connectors 91 extend through suitable openings in the bottom of the insulating base 9.

The circuit through each pole unit of the circuit breaker 3 extends from the right-hand terminal 91. through the conductor 23, the contacts 21, 27, the contact arm 29, a flexible conductor 97 that is secured to the contact arm 29, a terminal member 99 that is secured to the base 9 by means of a bolt 101, a unitary rigid main conductor 93 that is secured to the terminal 99 by bolts means 103, to the other terminal connector 91. Bolt means 103 and additional bolt means 105 fixedly secure the conductor 93 on the base 9.

The circuit break 3 is manually operated to the open position by movement of the handle 71 in a counterclockwise (FIG. 2) direction from the ON to the OFF position. During this movement, the line of action of the overcenter springs 75 is moved to the left to an overcenter position to efiect collapse of the toggle 41, 47 to pivot the switch arm 31 for the center pole in a counterclockwise direction about the associated pivot 35 to an open position which movement, because of the connection of all of the switch arms 31 by means of the common tie bar 37, simultaneously moves all of the three switch arms 23 and contact arms 29 to the open position.

The circuit breaker is manually closed by reverse movement of the handle 71 from the OFF position to the ON position. This movement moves the operating lever 63 to move the line of action of the overcenter springs 75 to the right to thereby erect the toggles 41, 47 moving all three of the switch arms 31 simultaneously to the closed position seen in FIGS. 2 and 3.

The latch and trip device 15 comprises a molded insulating base 113 and a molded insulating cover 115 secured to the base to enclose a molded insulating trip bar 119 that is common to all three of the pole units.

The trip bar 119 is pivotally supported on a bracket 121 that extends out of the base 113. The bracket 121 is supported on a supporting bracket 123 that is secured on the base 9 by means of the bolt 103. The trip bar 119 is supported on pivot pin means 124. The trip bar 119 comprises a metallic latch piece 125 that is fixedly secured in the insulating material of the trip bar during the molding of the trip bar. The latch structure 61 comprises a trigger latch 126 having slot means 127 therein that receives in a pin 128, that is mounted on the bracket 123, to mount the latch 126 for pivotal and sliding movement on the pin 128. The trigger latch 126 is biased in a clockwise direction by a spring 129. The trigger latch is latched against counterclockwise movement by a roller 130 that is supported on a latch 131 that is pivotally mounted on the bracket 123 by means of a pin 132. The latch 131 engages the latch piece 125 of the trip bar 119 to prevent counterclockwise movement of the latch 131. The torsion spring 129 biases the latch 131 in a clockwise direction. When the trip bar 119 is rotated counterclockwise to the tripping position, the latch piece 125 releases the latch 131 which moves counterclockwise to release the trigger latch which moves counterclockwise to thereby release the member 51 which moves clockwise to trip the breaker. The torsion spring 129 resets the latches 126 and 131, and a compression spring 133 resets the trip bar. When the breaker is reset the member 51 Wipes past the latch 126, with the slot 127 permitting sliding movement of the latch 126, to the reset position wherein the latch 126 again latches the member 51.

The circuit breaker is automatically tripped by operation of the trip actuator 16, in a manner to be hereinafter described, whereupon the trip actuator operates to rotate the trip bar 119 (FIG. 2) counterclockwise to release the latch structure 61. Upon release of the latch structure 61, the member 59 is released whereupon the springs 75 operate to rotate the member 59 in a clockwise direction about the pivot 57 and to collapse the toggle 41, 47 to thereby pivotally move the three switch arms 31 in a counterclockwise direction to the open position in a manner well known in the art.

During the automatic opening operation, the line of force of the springs 75 operates to move the operating lever 63 and handle 71 to an intermediate position between the ON and the OFF positions in a well known manner to thereby provide a visual indication that the circuit breaker has automatically been tripped.

Following an automatic tripping operation, it is necessary to reset and relatch the circuit breaker mechanism before the contacts can be closed. This is effected by moving the handle 71 to the full OFF position. During this movement, a pin 13'! that is supported on the operating lever 63, engages a shoulder 139 on the member 51 moving the member 51 in a counterclockwise direction about the pivot 57. Near the end of this movement, the free or latching end 59 of the cradle cams past the latch 126 to a reset position wherein the cradle 59 is again latched by means of the latch structure 61. The breaker contacts can then be closed in the previously described manner by movement of the handle 71 to the ON position.

A single trip actuator 16 (FIGS. 1 and 3-6) is mounted in one of the outer pole units (the lowermost pole unit as seen in FIG. 1) of the circuit breaker 3. The trip actuator 16 comprises a non-magnetic plate 149 that is secured to the base 13 of the latch and trip device 15 by means of a pair of bolts 151 that extend through the plate 149 and that are threaded into tapped inserts in insulating projections 153 that are molded integral with the member 113. A sheet metal U-shaped magnetic frame member 155 is fixedly secured, at the free ends of the legs thereof, to the non-magnetic plate 149. As can be seen in FIGS. 5 and 6, the U-shaped magnetic frame 155 comprises a pair of parallel legs or side magnetic means 157 and a magnetic end part or bight part 159. An elongated armature structure 161 comprises an elongated non-magnetic rod 163 and a tubular magnetic armature 165 supported on the rod intermediate the ends of the rod. The armature 165 is fixedly secured on the rod 163 by pin means 167. The non-magnetic rod 163 comprises a first end part 169 that protrudes through an opening in the non-magnetic plate 149 and a second end part 171 that protrudes through an opening in the bight portion 159 of the magnetic frame 155. The openings in the plate 149 and bight portion 159 that received the rod 163 are large enough to permit free movement of the rod 163 and small enough to guide the rod 163 for rectilinear reciprocal movement. The rod 163 is provided with a tapped opening at the end 169 thereof for receiving a bolt 173 that is threaded into the tapped opening, to permit adjustment of the trip actuator. A nut 175 on the bolt 173 fixes a washer 177 against the end of the rod 163 with the washer 177 serving as a spring support for a compression spring 179 that operates between the washer 177 and plate 149 to bias the armature structure 161 to the left as seen in FIGS. and 6. A bolt 181 is threaded into the other end 171 of the rod 163 to capture one end of a C-shaped spring 183 on the rod 163. The other end of the C-shaped spring 183 protrudes through an opening 185, FIG. 4 in a lever 187 that is pivotally supported intermediate the ends thereof on a pair of brackets 189 by means of a pin 191 (FIG. 4). As can be seen in FIGS. 5 and 6, the brackets 189 are fixedly supported on the frame 155 by screws 195. An insulated conducting coil 201 is supported in the frame 155 around the armature 165 with the center opening of the coil 201 being large enough to permit rectilinear movement of the armature structure 161 therethrough. A pair of

permanent magnet members

203 and 205 are supported in the frame 155 on opposite sides of the armature structure 161. During assembly of the trip actuator 16, after the coil 201, armature structure 161 and

permanent magnets

203, 205 are in place between the legs of the U-shaped magnetic frame 155, a pair of insulating plates 209 and 211 (FIG. 4) are mounted in position between the bight portion 159 of the frame 155 and the non-magnetic plate 149 to close off the two open sides of the frame 155. The lower insulating plate 209 is provided with an opening therein for receiving a pair of insulated conductors 215 that are connected to the coil. As can be seen in FIG. 1, the conductors 215 extend out through an opening in the side wall of the circuit breaker housing and they are connected to an overcurrent protective device 219 that is mounted externally of the circuit breaker housing 9, 11. The overcurrent protective device, which is disclosed only partly at 219 in FIGS. l-3, is of the type more specifically described in the patent application of John David Watson et al., Ser. No. 765,584 filed Oct. 7, 1968. The protective device 219 includes three transformer type current monitors for sensing the load current in a three- Wire system (four current monitors when a four-wire system is being protected) and a solid-state adjustable static sensor that operates in response to a signal from any of the monitors to pulse the coil 201 of the trip actuator 16 with a DC current. As the current monitors detect overload currents, short circuit currents and ground fault currents, these signals are passed to the static sensor which in turn pulses the coil of the trip actuator to trip the breaker. The static sensor is adjustable to provide a variety of time-current tripping curves thereby providing systems designers and designers of switchboards and power centers with flexibility for obtaining selective tripping as well as excellent coordination with other breakers or protective devices in an electrical system.

Referring to FIGS. 4 and 5, the trip actuator 16 is shown therein in the initial or non-tripping position. The armature structure 161 is maintained in this initial position against the bias of the spring 179 by the magnetic flux that is supplied by the

permanent magnets

203, 205. The magnetic flux from the permanent magnet 205 works in a magnetic circuit that extends from the magnet 205 through the small air gap between the magnet 205 and armature 165, the armature 165, the bight portion 159 of the magnetic frame 155, the upper leg 157 (FIG. 5) of the magnetic frame back through the permanent magnet 205. The magnetic flux from the permanent magnet 203 Works in a magnetic circuit from the magnetic member 203, through the small air gap between the magnetic member 203 and armature 165, the armature 165, the bight portion 159 of the magnetic frame 155, through the lower leg 157 (FIG. 5) of the magnetic frame 155 back through the permanent magnet 203. The magnetic flux from the

permanent magnets

203, 205 is strong enough to maintain the armature structure 161 in the initial or non-tripping position seen in FIGS. 4 and 5 in which postion the armature engages the bight portion 159 of the magnetic frame 155. When the coil 201 is pulsed by the DC current from the overcurrent protective device 219, the reluctance of the above-mentioned magnetic circuits is increased and the spring 179 overcomes the holding force of the

magnets

203, 205 whereupon the armature structure 161 is snapped to the left moving to the tripping position seen in FIG. 6 which position is limited by the engagement of the armature 165 with the non-magnetic plate 149. Upon movement of the armature structure 161 to the tripping position the screw 173 engages the trip bar 119 (FIGS. 1-3) to pivot the trip bar 119 counterclockwise (FIGS. 2 and 3) to the tripping position to effect a tripping operation in the manner hereinbefore described. As the circuit breaker contacts are moved to the open position, a bracket 225 (FIG. 3), that is fixedly supported on the switch arm 31 in the one pole unit of the breaker, moves against the lower end of the lever 187 to pivot the lever 187 clockwise from the tripping position seen in broken lines in FIG. 3 to the reset initial position seen in full lines. During this movement the lever 187, operating through the spring 183, pulls the armature structure 161 from the tripping position seen in FIG. 6 to the reset initial position seen in FIGS. 35. The force of the operating springs 75 moving the switch arms 31 to the open position is strong enough to easily overcome the force of the spring 179 of the trip actuator 161. As was hereinbefore set forth, the protective device 219 operates merely to pulse the coil 201 so that when the armature structure 161 is moved back to the reset position seen in FIGS. 35 the magnetic flux from the

permanent magnets

203, 205 will automatically operate to maintain the armature structure 161 in the initial position, and when the circuit breaker is reset and closed, with the bracket 225 (FIG. 3) moving away from the lever 187, the armature structure 161 will be maintained in the initial position until the coil 201 is again pulsed to effect another tripping operation. With the armature structure 161 in the tripping position seen in FIG. 6, the flux from the

magnetic members

203 and 205 cooperates with the spring 179 to maintain the armature structure 161 in the tripping position. As can be understood with reference to FIG. 6, the fiux from the magnet 203 operates through the magnet 203, the space between the magnet 203 and armature 165, the non-magnetic gap (on the left as seen in FIG. 6) which includes the nonmagnetic plate 149, through the lower leg 157 of the magnetic frame and through the permanent magnet 203. The flux from the permanent magnet 205 operates through the magnet 205, the small gap between the magnet 205 and armature 165, the armature 165, the nonmagnetic gap (on the left as seen in FIG. 6) which includes the non-magnetic plate 149, the upper magnetic leg 157 of the magnetic frame 155 and back through the permanent magnet 205. Since some of the magnetic flux from the permanent

magnetic members

203 and 205 still operates through the armature 165 and the gap on the right (FIG. 6) between the armature 165 and through the bight portion 159 of the magnetic frame and back through the legs of the magnetic frame 155, the

full force of the

magnets

203 and 205 is not working against movement of the armature structure 161 back to the initial or non-tripping position. Thus, it is only necessary that the combination of the spring force 179 and the magnetic flux from the

magnet members

203, 205 be sufficient to provide a stable tripping position as seen in FIG. 6 and not so great as to significantly resist closing movement of the switch arm 31 (FIG. 3) which resets the armature structure 161.

As was hereinbefore set forth, the elongated rod 169 is non-magnetic. Thus, when the armature structure 161 is in the tripping position seen in FIG. 6, there is a nonmagnetic gap between the armature 165 and the bight portion 159 of the magnetic frame 155. Moreover, the non-magnetic rod 169 can move freely between the two positions thereof guided in the bight portion 159 of the magnetic frame 155.

With the spring member 183 connecting the lever 187 and armature structure 161, manufacturing tolerances and positioning of parts in the breaker is less critical in that if the bracket 225 (FIG. 3) moves past the position which resets the armature structure 161 in the initial position, the spring 183 will flex without applying damaging forces to the parts of the trip actuator 161.

Another embodiment of the invention is illustrated in FIG. 7. In FIG. 7, the reference characters are the same as those hereinbefore used except for the three reference characters which are primed. As can be understood with reference to FIG. 7, the insulating tie bar 37' is supported for pivotal movement about an axis 38 thereof to move the switch arm 31' between open and closed positions. The switch arm 31 (On the contact side of the pivot 38) engages the lever 187 to reset the armature structure 161. Other than the above-described modification, the breaker and trip actuator 161 operate in the same manner as was hereinbefore described with reference to FIGS. 1-6.

I claim as my invention:

1. 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 trip member movable to a tripping position to effect release of said operating mechanism, trip means comprising a magnetic trip actuator, said magnetic trip actuator comprising a support, an elongated armature structure supported on said support for lengthwise generally rectilinear movement, permanent magnet means providing magnetic flux to maintain said armature structure in an initial position, biasing means biasing said armature structure toward a tripping position, coil means energizable toaffect said magnetic flux to thereby effect release of said armature structure, upon release of said armature structure said biasing means operating to move said armature structure to a tripping position during which movement said armature structure at one end thereof operates said trip member to the tripping position, and upon opening of said contacts means operating the other end of said armature structure to reset said armature structure in said initial position.

2. A circuit breaker according to claim 1, a reset lever pivotally supported intermediate the ends thereof, means operatively connecting said armature structure at said other end of said armature structure to said reset lever on a first side of the pivot of said reset lever, and upon opening of said contacts said operating mechanism engaging said reset lever on the opposite side of said pivot of said reset lever and pivotally moving said reset lever to reset said armature structure in said initial position.

3. A circuit breaker according to claim 2, and said means connecting said reset lever with said armature structure comprising a resilient connecting means.

4. A circuit breaker according to claim 1, said support comprising a sheet metal U-shaped frame of magnetic material, a non-magnetic plate connected to said magnetic frame at the free ends of the opposite legs of said magnetic frame, said armature structure comprising a magnetic armature disposed between the legs of said magnetic frame and rod support means at opposite ends of said armature, said rod support means at one end thereof extending through an opening in said non-magnetic frame and at the other end thereof extending through an opening in the bight portion of said magnetic frame to support said elongated armature structure for rectilinear lengthwise movement, said permanent magnet means being positioned between the legs of said magnetic frame, said armature structure in said initial position thereof being positioned with said armature in proximity to the bight portion of said magnetic frame, in said initial position of said armature structure said permanent magnet means supplying magnetic flux that operates through said armature and said magnetic frame to maintain said armature structure in said initial position, said coil means being positioned between the legs of said magnetic frame and having opening means therein through which said armature structure extends, upon release of said armature structure said biasing means moving said armature structure to move said armature structure toward said non-magnetic plate to said tripping position during which movement said armature structure at said one end thereof operates said trip member to the tripping position.

5. A circuit breaker according to claim 4, a support bracket supported on said magnetic frame, a reset lever pivotally supported intermediate the ends thereof on said support bracket, means connecting said reset lever on the first side of the pivot of said reset lever to said other end of said armature structure, and upon opening of said contacts said operating mechanism operating against said reset lever on the other side of the pivot of said reset lever to pivotally move said reset lever during which movement said reset lever pulls said armature structure to reset said armature structure in said initial position.

6. A circuit breaker according to claim 5, and said means connecting said reset lever with said other end of said armature structure comprising a resilient connecting means.

7. 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 trip member movable to a tripping position to effect release of said operating mechanism, a magnetic trip actuator, said trip actuator comprising support means, said support means comprising a magnetic frame generally U-shaped at least in cross section, said magnetic frame comprising a magnetic bight part at one end thereof and magnetic side means, a non-magnetic end part at the other end of said magnetic frame, an elongated armature structure comprising a magnetic armature positioned within said magnetic frame and rod support means supporting said armature, said rod support means at one end extending through an opening in said magnetic bight part and at the other end thereof extending through an opening in said non-magnetic end part to support said elongated armature structrue for lengthwise rectilinear movement, permanent magnet means providing magnetic flux in a magnetic circuit which extends through said armature and said magnetic frame to maintain said armature structure in an initial position in which initial position said armature is in proximity to said magnetic bight part, biasing means 'biasing said armature structure to bias said armature toward said non-magnetic end part, coil means energizable to affect said magnetic flux to thereby effect release of said armature structure from said initial position, upon release of said armature structure said biasing means operating to move said armature toward said nonmagnetic end part to thereby move said armature structure to a tripping position, said armature structure upon movement thereof to said tripping position operating to move said trip member to the tripping position, and upon opening of said contacts said operating mechanism operating to automatically reset said armature structure in said initial position.

8. A circuit breaker according to claim 7, and said rod support means comprising an elongated non-magnetic rod member.

9. A circuit breaker according to claim 7, said magnetic frame comprising a U-shaped sheet-metal magnetic member, said permanent magnet means comprising a pair of permanent magnet members supported on opposite sides of said armature structure between the legs of said U-shaped magnetic frame, in said initial position of said armature structure a first of said permanent magnet members supplying magnetic infiux that operates through said armature said bight part and a first leg of said magnetic frame and the second of said permanent magnet members supplying magnetic flux that operates through said armature said bight part and the second leg of said magnetic frame whereby said first and second magnet members operate to maintain said armature structure in said initial osition with said armature engaging the bight part of said magnetic frame, and upon movement of said armature structure to said tripping position said armature engaging said non-magnetic end 10 part to limit movement of said armature structure in said tripping position.

10. A circuit breaker according to claim 7, a support bracket mounted on said magnetic frame, a reset lever pivotally supported intermediate the ends thereof on said support bracket, a spring member connected between said armature structure and said reset lever on a first side of the pivot of said reset lever to connect said reset lever and armature structure, and said operating mechanism upon opening movement of said contacts operating against said reset lever on the opposite side of the pivot of said reset lever to pivotally move said reset lever during which movement said spring member pulls said armature struc ture from said tripping position to the initial position to thereby reset said armature structure.

References Cited UNITED STATES PATENTS 3,072,765 l/1963 Hauser 335-174 3,116,388 12/1963 Hobson 335l73 3,305,806 2/1967 Norden 335-l74 GEORGE HARRIS, Primary Examiner H. BROOME, Assistant Examiner