US3544932A

US3544932A - Circuit breaker with improved trip means

Info

Publication number: US3544932A
Application number: US770305A
Authority: US
Inventors: Edmund W Kuhn
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1968-10-24
Filing date: 1968-10-24
Publication date: 1970-12-01
Anticipated expiration: 1987-12-01
Also published as: US3544931A; ES372811A1; BR6913626D0; BE740593A; FR2021495A1; GB1282155A

Description

Dec. 1, 1970 E. w. KUHN CIRCUIT BREAKER WITH IMPROVED TRIP MEANSy med oct. 24, 1968 5 SheQts-Shcet 1 l INVENTOR Edmund W. Kuhn WITNESSES flaQ/M MJ@ ATTORNEY Dec. 1, 1970 E. w. KUHN 3,544,932

CIRCUIT BREAKER WITH IMPROVED TRIP MEANS Filed 0611.24, 1968 5 Sheets-Sheet 2 FIGA. |99

FIG2.

Dec. 1, 1970 l E. w. K U HN 3,544,932

CIRCUIT BREAKER WITH IMPROVED TRIP MEANS Filed OCl.. 24, 1968 Sheets-Sheet 5 United States Patent O 3,544,932. CIRCUIT BREAKER WITH IMPROVED TRIP MEANS Edmund W. Kuhn, Pittsburgh, Pa., assignor to Westing- House Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Oct. 24, 1968, Ser. No. 770,305 Int. Cl. H01h 9/20 U.S. Cl. 335-174 9 Claims ABSTRACT F THE DISCLOSURE A circuit breaker having improved trip means. The trips means is a magnetic trip device having magnetic pole-piece means, a magnetic fixed keeper, a moveable keeper having an actuator connected to the moveable keeper to trip the breaker upon the occurrence of abnormal or over load current conditions.

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 ux from a first circuit to a second circuit to effect release of a movable keeper in the rst 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 with a movable keeper positioned at one end of the trip device and an actuator operatively connected to the movable keeper and extending to the other end of the trip device to actuate the operating mechanism of the circuit breaker in order to effect an opening operation of the circuit breaker upon the occurrence of certain over load current conditions.

Another object of this invention is to provide an irnproved circuit breaker comprising a flux-transfer trip device having a movable keeper movable to a tripping position to effect a tripping operation of the circuit breaker and resilient reset means operated by a rigid part of the circuit breaker operating mechanism to reset the movable keeper without applying damaging forces to the parts of the trip device.

A further object of this invention is to provide a circuit breaker with an improved flux-transfer trip device comprising a movable keeper and an actautor connected to the movable keeper with shock-absorbing means for permitting movement of the actuator relative to the movable keeper under shock conditions.

A more general object of this invention is to provide a circuit breaker with an improved flux-transfer 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 may be pulsed by a low energy electrical signal supplied under abnormal or overload conditions in order to effect a tripping operation of the circuit breaker. The trip device comprises a pair of spaced pole pieces with a movable keeper positioned at one end of the pole pieces and a xed keeper positioned at the other end of the pole pieces. A permanent magnet structure is positioned between the pole pieces and between the tixed and movable keepers in order to supply magnetic flux. The magnetic device is constructed with a gap between the fixed keeper and the pole pieces. The movable keeper, in the set position thereof, engages the pole pieces. With the Lice movable keeper in the set position, most of the magnetic iiux from the permanent magnet structure operates through a magnetic circuit, that comprises the movable keeper, to work to maintain the movable keeper in the set position. The remainder of the magnetic flux passes through another magnetic circuit that includes the fixed keeper. An actuator, that is operatively connected to the movable keeper at one end thereof, extends through opening means in he trip device and is operatively connected, at the other end thereof, to a trip member. Spring means biases the movable keeper and actuator toward a tripping position. A pair of coils are conneced in series and to the magnetic device in order to buck the magnetic ux through the one magnetic circuit to raise the reluctance of the one magnetic circuit when the coils are pulsed to thereby effect a transfer of magnetic flux from the one magnetic circuit to the other magnetic circuit in order to effect release of the movable keeper. Upon release of the movable keeper, the spring means biases the movable keeper and actautor to a tripping position to operate the trip member to effect a tripping operation of the circuit breaker. The movable keeper is operatively connected to the actuator through a shock-absorbing spring so that under shock conditions the actuator can move slightly relative to the movable keeper Without the full force of the shock of the actautor being transmitted to the movable keeper. Resilient reset means, which is operatively connected to the actuator, is engaged by a rigid part of the circuit breaker operating mechanism in order to reset the movable keeper and actuator during an opening operation of the circuit breaker. With the provision of resilient reset means the construction and positioning of parts is less critical and a rigid part of the operating mechanism can operate to reset the actuator and movable Ikeeper without applying damaging forces to the parts of the trip device. The magnetic device is mounted within an enclosure, and the actuator extends out through an opening in the enclosure Where the trip member and resilient reset means are operatively connected to the trip device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. y1 is a side elevational view, partly in section and with parts broken away, of a three-pole circuit breaker embodying 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 taken generally along the line lIII-III of FIG. 2;

FIG. 4 is a view similar to FIG. 3 with the trip device operated to the tripping position and With the circuit breaker tie bar still in the closed position;

FIG. 5 is a view similar to FIG. 4 with the circuit breaker tie bar in the open position and the trip device operated to the reset position;

FIG. 6 is a side sectional view of the trip device seen in FIGS. 3-5 with the reset member and trip member shown in full lines in the position illustrated in FIG. 5 and with the reset member shown in broken lines in the position illustrated in FIG. 3;

FIG. 7 is a view similar to FIG. 6 with the trip device shown in the tripping position illustrated in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, there is shown, in FIG. 1, fa circuit breaker 5 comprising a metallic supporting frame structure indicated generally at 7 and a circuit-breaker structure indicated generally at 9 supported on the supporting frame structure 7. Except for the trip device that will be hereinafter more specifically described the circuit breaker 5 is identical to the circuit breaker described in 3 the patent to G. D. Gamel et al. Pat. No. 3,045,083, issued July 17, 1962. Thus, only a brief description of the circuit breaker will be provided herein.

The circuit breaker 5 is a three-pole circuit breaker with each pole comprising a stationary contact structure 11 and a movable contact structure 13. Each of the movable contact structures 13 is supported on a contact arm 15 that is supported for movement about a xed pivot 17. A common elongated rigid tie bar 19 extends across the three-pole units. In each pole unit a separate insulating connector 21 is connected to the tie bar 19 and to the associated contact arm to connect the three contact arms 15 for simultaneous movement upon movement of the tie bar 19. The tie bar 19 is operated between open and closed positions by operation of an operating mechanism indicated generally at 23.

The operating mechanism 23 comprises an operating lever 25 supported on a pivot pin 27 that is supported'on the supporting structure 7. The lever 25 is pivotally connected to the tie bar 19 to operate the tie bar 19. An operating linkage, comprising

toggle links

29, 31 and 33, is provided to hold the lever 25 in the closed position and to operate the lever 25 between the open and closed positions. The toggle link 29 is pivotally connected to the lever 25 by means of a pivot pin 35. The link 31 is connected to the link 29 by means of a knee pivot pin 37 and pivotally connected to the link 33 by means of a knee pivot pin 39. The link 33 is supported for pivotal movement on a fixed pivot pin 41 that is mounted on the supporting structure 17.

The

linkage

29, 31, 33 comprises two toggles one of which 29, 31 functions as a tripping toggle and the other of which 31, 33 functions as a closing toggle. The

tripping toggle

29, 31 is normally slightly underset above a line drawn through the pivot pins 39, 35, and the

closing toggle

31, 33 is normally slightly underset below a line drawn through the

pivots

37, 41.

The

tripping toggle

29, 31 is normally biased in a direction to cause its collapse by springs 43, that are positioned in each pole unit between the support structure 17 and movable contact arm 15, which bias the contact arms 15 in an opening direction and bias the connecting members 21 toward the left. The

tripping toggle

29, 31 is normally prevented from collapsing by means of a main latch member 45 that is pivoted on a pin 47 and connected by a link 49 to the knee pivot 37 of the

toggle

29, 31. The link 49 is pivotally connected to the latch 45 by means of a pivot pin 51.

The main latch 45 is held in latching position by an intermediate latch lever 53 that is pivoted on a pin 55 that is supported on the supporting structure 17. The latch 53 carries a latch roller 57 which normally engages the main latch 45 to releasably hold the main latch in the latching position seen in FIG. 1. The latch lever 53, at its lower end, carries a latch portion 59 that normally engages a latch roller 61 on a latch member 63 that is supported for pivotal movement on a pin 65 that is supported on the support structure 7. The

latches

53 and 63 are biased by spring means (not shown) to the latching positions seen in FIG. 1.

As long as the main latch 4S is held in latching position by the latching mechanism just described, the tripping

toggle

29, 31 will, through the link 49, be held in the closed position. The

closing toggle

31, 33 is normally prevented from collapsing by a shouldered support member 69 pivoted on the pin 55 and biased by a spring 71 into supporting engagement with the knee pin 39 of the

toggle

31, 33.

The circuit breaker is shown in FIG. l in the closed and latched position with the support member 69 supporting the

closing toggle

31, 33 in its extended thrust transmitting position. The circuit breaker is automatically tripped open by operation of a trip device 75 indicated by broken lines in FIG. 1 and shown in FIGS. 2 7. The trip device 75, which operates against a part 77, that is 4 ixedly secured to the latch 63, will be hereinafter more speciiically described.

Upon the occurrence of an abnormal or overload condition above a predetermined value in any of the pole units, the trip device is operated to operate against the part 77 of the latch 63 to pivot the latch 63 counterclockwise (FIG. 1) to thereby disengage the latch roller 61 from the latch portion 59 of the latch lever 53. The latching engagement of the main latch 45 with the latch roller 57 is of the slip-oit type, and as soon as the latch lever 53 is released it is moved to an unlatching position by the upward force applied to the main latch 45 through the link 49. The tripping

toggle

29, 31 immediately collapses permitting counterclockwise movement of the operating lever 25 and opening movement of the tie rod 19 with the tie rod 19 moving from the position seen in FIG. 1 to the position seen in FIG. 5 during which movement the contact arms 15, which are operatively connected to the tie bar 19 by means of the connectors 21, pivot about the pivots 17 from the closed position seen in FIG. 1 to an open position wherein the movable contacts 13 are disengaged from the stationary contacts 11. During the collapse of the tripping

toggle

29, 31, a portion of the toggle link 31 engages and actuates the support member 69 against the bias of the spring 71 to a non-suporting position thereby freeing the

closing toggle

31, 33. The closing toggle thereupon collapses dovmward- 1y to reset and relatch the tripping

toggle

29, 31.

The

linkages

29, 31 and 31, 33 are trip free. During an opening operation, the contacts cannot be closed until the closing toggle collapses resetting the linkages for a closing operation.

The opening operation can also be initiated manually by a trip lever (not shown) that also rotates the latch 63 to the unlatching position.

A spring closing mechanism indicated generally at 79 is provided for manually closing the breaker. The spring closing mechanism 79 is partially enclosed within a U- shaped housing S1 that is xedly secured to the support structure 7. The spring closing mechanism 79 comprises a closing spring 83 that is supported between a top spring support 85 and a bottom spring support 87, which spring supports are supported for rectilinear movement within the housing 81. A guide bolt 89 is connected to the bottom spring support 87 to move with the bottom spring support 87, and a guide bolt 91 is connected to the top spring support 85 to move with the top spring support 85. A toggle link 93 is pivotally connected to a cross bolt 95 that is connected to the top spring support, and a toggle link 97, that is pivotally connected to a stationary cross bolt 99, is pivotally connected to the toggle link 93. The bottom spring support 87 is connected to a cross bolt 101 that moves with the bottom spring support 87. The toggle link 97 is also pivotally connected to a vertically movable thrust rod 105. The thrust rod has an opening in its upper end for receiving the pin 39.

A lift link 109 is provided for lifting the bottom spring support 87. The lift link 109 is a at member that passes through an opening in the top spring support 85 and has an angle shaped lower portion 111 projecting through an opening in the bottom spring support 87. The cross bolt 101 passes through an opening in the portion 111 of the lift link 109 so that upward movement of the lift link 109 will lift the bottom spring support 87.

A handle structure indicated generally at 113 is provided to operate an operating shaft 115 (FIG. 2). The handle structure 113 is more specifically described in the above-mentioned application of G. D. Gamel et al. U.S. Pat. No. 3,045,083. The shaft 115 (FIG. 2) is supported for movement about a fixed axis. A plate 117, which is xedly secured to the shaft 115, is pivotally connected to the upper end of the lift link 109 by means of a pin 119.

The parts of the circuit breaker are shown in FIG. 2 in the open position. In order to close the breaker, the handle structure 113 (FIG. 1) is rotated to rotate the shaft 11S (FIG. 2) clockwise. As the plate 117 (FIG. 2) rotates clockwise, the link 109 is lifted to lift the bottom spring support 87. Upward movement of the top spring support 85 is prevented because the

links

93, 97 are on dead center. The upward movement of the link 109, therefore, lifts the bottom spring support 87 to compress the spring 83 between the spring supports 87, 85. As the link 109 moves upward (FIG. 2) a roller 123|, that is connected to the pin 119, operates against the toggle link 33 (FIG. 1), which toggle link 33 is collapsed when the breaker is in the open position of FIG. 2, to pivot the toggle link 33 counterclockwise about the pivot 41 raising the thrust rod 105 which rotates the toggle link 97 to move the

toggle

93, 97 olf of dead center permitting the

toggle

93, 97 to collapse to thereby permit upward movement of the top spring support 85 under the force of the charged spring 83 which has been charged by the upward movement of the lower spring support 87. The Spring 83 then expands rapidly moving the top Spring support 85 upwardly to force the thrust rod 105 upward. Upward movement of the thrust rod 105 from the open position to the closed position operates, with the tripping

toggle

29, 31 in the thrust-transmitting position, to move the

closing toggle

31, 33 to the closed position seen in FIG. 1 during which movement the lever 2'5 is pivoted clockwise about the pivot 27 to move the tie bar 19 from the open position seen in FIG. to the closed position seen in FIG. 1. Movement of the tie bar 19 to the closed position operates through the connectors 21 to pivot the three contact arms 115, about the pivots 17, to the contactclosed position seen in FIG. l.

The trip device 75 (FIGS. 6 and 7) comprises a trip housing structure 127 and a magnetic device 129 supported within the housing 127. The magnetic device 129 comprises a pair of magnetic

steel pole pieces

131, 133, a conducting coil 135 around the pole piece 131, a conducting coil 137 around the pole piece 133 and four

permanent magnet members

139, 141, 142, 143, which

members

139, 131, 135, 137, 139, 141, 142 and 143 are all potted in an insulating epoxy resin 145 which encapsulates these members and supports them as a unitary structure. The

permanent magnet members

139, 141, 142, 143 form a permanent magnet structure indicated generally at 149 which is formed of the four members merely to facilitate assembly using readily available magnet members. The permanent magnet structure 149 is a rubber bonded barium ferrite permanent magnet material that is available under the trade name Plastiform As can be understood with reference to FIG. 6, an opening 151 is drilled through the permanent magnet structure 149 and insulating casing 145. A magnetic steel fixed keeper 153 is iixedly secured to one end of the

pole pieces

131, 133 with an insulating sheet 155 sandwiched between the fixed keeper 153 and

pole pieces

131, 133 to provide a gap between the xed keeper 153 and the

pole pieces

131, 133. As can be understood with reference to FIG. 6, the opening 151 extends through the insulating plate 155 and the lixed keeper 153. The xed keeper 153 is secured to the pole pieces 131 by a pair of nuts 157 that are threaded onto bolts 159 that are embedded in the epoxy 145 when the epoxy 145 is potted. An actuating rod 161 extends through the opening 151. As can be understood with reference to FIG. 6, the opening 151 is drilled such that there is a small-diameter portion 163 of the epoxy resin which receives the rod 161 to guide the rod for rectilinear back-and-fourth movement in the opening 151. The actuating rod 151 extends through an opening in a magnetic steel movable keeper 165. A washer 167 is provided on the outer end of the rod 161, and a nut 169 is threaded on the rod 161 against the washer 167 so that as the rod 161 is moved to the right (FIG. 6) this movement will pull the movable keeper 165 to the right to the set position seen in FIG. 6 wherein the movable keeper 165 engages the

pole pieces

131, 133. A shock-absorbing coil spring 171 is supported between a spring support 173 that engages a shoulder portion of the 75 rod 161 and a spring support 175 that engages the movable keeper 165. A coil spring 179 is supported between a spring support 181 that engages a shoulder of the actuating rod 161 and a spring support 183 that engages the housing 127 to actuate the actuating rod 161 to the left (FIG. 6) upon release of the movable keeper 165.

The trip device also comprises a supporting bracket 185 that is fixed to the one end of the housing 127, a trip member 187 that is pivotally supported on a pin 189 that is supported on the 'bracket 185 and a reset member 191 that is pivotally supported on a pin 193 that is supported on the bracket 185. The trip member 187 is a generally U-shaped member with the pin 189 passing through the opposite legs thereof. The bight portion of the trip member 187 is extended outward to provide an actuating extension 195. The reset member 191 is a resilient reset member comprising a rigid generally U-shaped member 197 and a resilient leaf-spring 199 secured to the member 197. The pin 193 extends through the legs of the U-shaped member 197. A tension spring 201 is connected to a bentover portion of the member 197 at one end thereof and to a bent-over portion of the supporting bracket 185 at the other end thereof to bias the reset member 191 in a clockwise (FIG. 6) direction. The member 197 is provided with an extension 203 that engages the bight portion of the trip member 187 between the legs of the trip member 187 in a manner to be hereinafter described. The trip member 187 is pivotally connected to the actuating rod 161 by means of a loose-tting pin 207.

The trip device 75 is shown in FIG. 6 in the set position with the leaf-spring member 199 shown in broken lines in the position that the member 199 would assume under the bias of the spring 20-1 when the tie bar 19 is in the contactclosed position shown in broken lines. The trip device 75 and

parts

19, 77 are shown in FIG. 3 in the set position with the tie bar 19 shown in the contact-closed position and the part 77 of the latch `63 shown in the latching position. As can be understood with reference to FIG. 6, the permanent magnet structure 149 generates magnetic flux which passes through the magnet structure 149, the pole piece 133, the movable keeper 165, the pole piece 131 and back through the magnet structure 149. IPart of the flux generated in the magnet structure 149 passes through the magnet structure 149, the pole piece 133, the gap 155, the fixed keeper 153, the gap 155, the pole piece 131 back through the magnet structure 149. Thus, there are two magnetic circuits in the magnetic device 129 with the greater portion of the magnetic flux from the magnet structure 149 passing through the one magnetic circuit which includes the movable keeper 165 and with the remainder of magnetic iiux passing through the higherreluctance other magnetic circuit which includes the gap and the fixed keeper 153.

The

coils

135, 137 are connected in electrical series and pulsed by a DC current, in response to an abnormal or overload condition in any of the three pole units of the 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, tiled Oct. 7, 1968. The polarity of the

coils

135, 137 is such that when the coils are pulsed the eurent in the coils bucks the magnetic flux in the magnetic circuit that includes the movable keeper to raise the reluctance of the magnetic circuit that includes the movable keeper 165 whereupon magnetic flux transfers to the magnetic circuit that includes the xed keeper 153. Thus, when the

coils

135, 137 are pulsed the movable keeper 165 is released and the charged kickout spring 179 moves the actuating rod 161 to the left to operate through the shock-absorbing spring 171 to move the movable keeper 165 from the set position seen in FIG. 6 to the tripping position seen in FIG. 7. Upon movement of the movable keeper 165 and actuating rod 161 from the set position to the tripping position seen in FIG. 7, the actuating rod 161 pivots the trip member 187 counterclockwise to the tripping position seen in FIGS. 7 and 4. As can be understood with reference to FIGS. 7, 4 and .1, when the trip member 187 moves to the tripping position the part 195 of the trip member 187 engages the part 77, that is connected to the latch 63 (FIG. 1) to pivot the latch 63 in a counterclockwise (FIG. l) direction about the pivot 65. This unlatching movement of the latch 63 (FIG. 1) serves to release the latch 53 to effect an opening operation of the circuit breaker in the same manner as was hereinbefore described.

The parts are shown in FIGS. 4 and 7 at the instant when the trip member 187 is moved to the tripping position With the tie bar 19 still shown in the closed position about to be operated to the open position as the latches are released. When the circuit breaker is operated to the open position the rod 19 moves from the position seen in FIGS. 4 and 7 (seen in broken lines in FIG. 6) to the open position seen in FIGS. 5 and 6. As the tie bar 19 moves to the open position seen in FIGS. 5 and 6, the tie bar engages the resilient leaf spring 199 of the resilient reset member 191 to pivot the reset member 191 in a counterclockwise direction about the pivot 193. During this movement, the projecting portion 203 of the reset member 191 engages the trip member 187 to pivot the trip member 187 in a clockwise direction about the pivot 189l moving the actuating rod 161 from the released or tripping position seen in FIG. 7 back to the set or reset position seen in FIG. 6. As the actuating rod 161 moves to the position seen in FIG. 6, the rod 161 operates through the washer 167 to pull the movable keeper 165 back into the set position in engagement with the

pole pieces

131, 133.

The

coils

135, 137, which were only momentarily pulsed l to effect the 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 a condition in one of the pole units that would operate the protective relay to again energize the

coils

135, 137. Thus, when the movable keeper 165 is re-engaged in the set position engaging the

pole pieces

131, 133 the magnetic flux will automatically transfer from the higher reluctance magnetic circuit that includes the fixed keeper 153 back through the lower reluctance magnetic circuit that includes the movable keeper 165 so that the magnetic flux in the circuit through the movable keeper 165 will again work to hold the movable keeper 165 in the set position seen in FIG. 6 until the

coils

135, 137 are again pulsed.

As can be understood with reference to the drawings, with the rigid tie bar 19 operating against a resilient leafspring member 199 the manufacturing tolerances and positioning of parts in the breaker is less critical in that when the tie bar 19 moves past the point where the movable keeper 165 engages the pole pieces the tie bar 19 will merely flex the leaf-spring 199 without applying damaging forces to the parts of the trip device.

Following an opening operation of the circuit breaker, the circuit breaker is manually closed by operation of the handle operating structure 113 (FIG. 1) in the same manner as was hereinbefore described. During the closing operation, the tie bar 19 moves from the full line position seen in FIG. 6 to the broken line position seen in FIG. 6 (from the position seen in FIG. 5 to the position seen in FIG. 3) whereupon the spring 201 biases the reset member 191 clockwise about the pivot 193 from the position seen in FIG. 6 to the position seen in FIG. 3.

With the trip device in the reset position, if the actuating rod 161 is moved slightly to the left under shock conditions, some of the shock force will be absorbed by the shock-absorbing spring 171 Without being directly applied to the movable keeper 165. The actuating rod 161 extends through an opening, in the movable keeper 165, that is large enough to permit relative movement of the rod to the left (FIG. 6) without moving the movable keeper 165. The spring 171, however, must be sufliciently stiff so that when the movable keeper 16S is released the movable keeper will be immediately biased to the left under the biasing force of the spring 179 operating through the rod 161 and spring 171.

I claim:

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, trip means comprising a rnagnetic device, said magnetic device comprising magnetic pole-piece means, a magnetic fixed keeper supported at a first end of said pole-piece means, a magnetic movable keeper at a second end of said pole-piece means opposite said first end, an elongated actuator operatively connected at one end thereof to said movable keeper and extending at the other end thereof past said fixed keeper, permanent magnet flux supplying means positioned between said fixed keeper and movable keeper and providing magnetic flux that operates in a first magnetic circuit through said pole-piece means and said movable keeper to maintain said movable keeper and said actuator in a set position in which set position said movable keeper is positioned against said pole-piece means, biasing means biasing said actuator and movable keeper away from said pole-piece means, means for effecting a transfer of magnetic flux from said first magnetic circuit to a second magneticcircuit which is through said pole-piece means and said fixed keeper whereupon said movable keeper is released, upon release of said movable keeper said biasing means biasing said movable keeper and said actuator away from said pole-piece means to bias said movable keeper and said actuator to a tripping position in which tripping position said movable keeper is spaced from said pole-piece means, upon movement of said movable keeper and said actuator to said tripping position said actuator at said other end thereof operating to effect release of said operating mechanism to thereby effect opening of said contacts, and means automatically moving said actuator and Said movable keeper back to said set position upon opening of said contacts.

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, and upon movement of said movable keeper and said actuator back 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 and said actuator in said set position.

3. A circuit breaker according to claim 2, said means for moving said movable keeper and said actuator back to said set position comprising resilient reset means operatively connected to said actuator, said operating mechanism comprising a movable member movable to an open position upon opening of said contacts and to a closed position upon closing of said contacts, and upon movement of said movable member to the open position said movable member engaging said resilient reset means and operating said resilient reset means to operate said actuator and said movable keeper back to said set position.

4. A circuit breaker according to claim 3, said circuit breaker comprising a multi-pole circuit breaker, a stationary contact and a movable contact for each pole unit, a separate movable contact arm carrying each of said movable contacts, a rigid tie bar common to all of said pole units and operatively connectedV to simultaneously move al1 of said movable contact arms, and said movable member that engages said resilient reset means being Said tie bar.

5. A circuit breaker according to claim 3, said operating mechanism comprising latch means movable to a releasing position to release said operating mechanism, said trip device comprising a trip member operatively connected to said actuator and movable upon movement of said movable keeper and said actuator to the tripping position to engage said latch means and to move said latch means to the releasing position, and said resilient reset means comprising a reset member separate from said trip member and supported to actuate said trip member said movable keeper and said actuator back to the set position upon opening of said contacts.

6. A circuit breaker according to claim 5, said trip means comprising a trip housing structure, said magnetic device being supported within said trip housing structure, said trip housing structure having opening means therein, said actuator extending out through said opening means, and said trip member and said resilient reset means being supported on said trip housing structure external of said trip housing structure.

7. A circuit breaker according to claim 4, means supporting said trip member on a first fixed pivot, means supporting said resilient reset means on a second fixed pivot separate from said first fixed pivot, means connecting said trip member with said actuator, spring means biasing said resilient reset means toward an initial position, upon release of said movable keeper said movable keeper said actuator and said trip member operatively moving to release said latch means with said resilient reset means remaining in said initial position, upon opening of said contacts said movable member engaging said resilient reset means and moving said resilient reset means to the set position during which movement said resilient reset means operates to move said movable keeper said trip member and said actuator back to the set position, and upon the occurrence of a subsequent closing operation said spring means biasing said resilient reset means back to said initial position during which movement of said resilient reset means said movable keeper said trip member and said actuator remain in said set position.

8. A circuit breaker according to claim 3, said magnetic device having opening means therein, said actuator comprising an elongated actuating rod operatively connected to said movable keeper at one end thereof and extending through said opening means past said fixed keeper, a trip member operatively connected to said other end of said actuating rod and movable upon movement of said actuating rod to effect release of said operating mechanism, and said resilient reset means being supported in proximity to said other end of said actuating rod and being operable to said reset position to move said actuating rod said movable keeper and said trip member back to the set position.

9. A circuit breaker according to claim 8, a first spring means biasing said actuating rod toward the tripping position, said movable keeper having an opening therein, said actuating rod at said one end thereof extending through said opening and being connected to said movable keeper to move said movable keeper with said actuating rod back to said set position, and a shock-absorbing spring connected between said actuating rod and said movable keeper to permit said actuating rod to move toward the tripping position under shock conditions with said movable keeper in the set position during which movement said actuating rod compresses said shock-absorbing spring and moves relative to said set movable keeper, upon release of said movable keeper said tripping spring operating said actuating rod to operate through said shockabsorbing spring to move said movable keeper and said actuating rod to the tripping position.

References Cited UNITED STATES PATENTS 2,278,971 4/1942 Boehne 335--179 2,840,663 6/1958 Horn 335-174 3,070,730 12/1962 Gray 335-256 3,072,765 l/l963 Hauser 335--174 3,202,886 8/1965 Kramer 335-254 BERNARD A. GILHEANY, Primary Examiner H. BROOME, Assistant Examiner