US2404950A - Circuit breaker - Google Patents

Description

July 3 0, 1946. R. c. DICKlNsoN l-:T AL 2,404,950.l

CIRCU'IT BREAKER Filed sept. 15, 1942 2 sheets-sheet 1 I laffe/2 July 30, 1946- R. c. DlcKlNsoN ET AL 2,404,950

CIRCUIT BREAKER Filed sept. 15, 1942 171g. 3. if

2 Sheets-Sheet 2 211 insa/arjan insu/@Mw lll,

WITNESSES:

45 and ffizz [ff/ammazz- BY 43 or ATTORNE Patented July 30, 1946 CIRCUIT BREAKER Robert C. Dickinson, Wilkinsburg, William H.

Stuellein, East McKeesport, and Fritz E. Florschutz, Wilkinsburg, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 15, 1942, Serial No. 458,358

(Cl. 20o-89) 18 Claims. l

This invention relates to circuit breakers and more particularly to a high-speed circuit breaker which is operated to automatically interrupt the circuit as a result of reversal of the current in the circuit controlled by the breaker.

An object of the invention is the pro-vision of an improved circuit breaker which is operated at high speed to open the contacts and in which the contacts are trip free oi the closing means.

Another object of the invention is to provide an improved circuit breaker in which the support frame for the breaker mechanism forms a part of the magnetic circuit for the holding magnet.

Another object of the invention is to provide a circuit breaker with an improved trip mechanism wherein a trip magnet core member forms a part of the magnetic circuit for a separately energized holding coil.

Another object of the invention is to provide a circuit breaker of improved construction which is safe and reliable in operation, and inexpensive to manufacture.

Another object of the invention is to provide an improved circuit breaker wherein a pivoted contact member is held in closed position by a latch member pivoted eccentrically of the contact member pivot and movable substantially radially to said pivot to release the contact member.

Another object of the invention is to provide an improved circuit breaker with a novel latch member which is movable longitudinally of itself to release a contact member and which is rotatable and longitudinally movable to reset position.

Another object of the invention is to provide a circuit breaker with an improved latch structure wherein a latch member which releasably connects a switch member to an operating member is longitudinally movable to disconnect the switch member from the operating member and wherein the latch member is rotatably and longitudinally movable to reconnect said switch member to the operating member.

Another object of the invention is to provide an improved operating mechanism for a circuit breaker wherein a latch is movable by a trip device to eiect opening of the contacts, the latch being movable by the operating mechanism to close the contacts.

Another object of the invention is the provision of an improved operating mechanism for a circuit breaker wherein a latch is operable by a trip device to effect opening of the breaker irrespective of the position of the operating mechanism, said latch being operable by the operating mechanism to close the breaker.

Another object of the invention is the provision of an improved circuit breaker operating mechanism wherein the circuit breaker is held latched in closed position by a holding magnet which acts to hold a latch in a position to connect the movable switch member to an operating member, the latch being operable by a relatively small component of the opening bias of the breaker to release the switch member upon a predetermined reduction of the magnetic ilux.

The novel features that are considered characteristic of the invention are set forth in Darticular in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description of one embodiment thereof when read in conjunction with the accompanying drawings, in which:

Fig. 1 is a side elevational view, partly in section, of a circuit breaker embodying the principles of the invention;

Fig. 2 is a fragmentary sectional View taken on line II-II of Fig. 1 showing the structural features of a portion of the magnetic structure of the trip electromagnet.

Fig. 3 is a front elevational View of the circuitbreaker.

Fig. 4 is a fragmentary elevational view, partly in section, of the breaker in the tripped open position.

Fig. 5 is a detail sectional view taken on line V-V of Fig. 1 showing the details of construction and mounting of the parts on the contact arm support shaft;

Fig. 6 is a sectional view taken on line VI-VI of Fig. l showing the construction and mounting of the holding coil.

Referring to Figs. 1 and 3 of the drawings, the circuit breaker includes a separable contact structure indicated generally at Il, an operating mechanism indicated generally by the reference character I3, a trip device I5, an arc blow-out magnet I'I and an arc chute indicated generally at I9.

The several elements comprising the circuit breaker are mounted on a framework comprising a pair of spaced upright support'bars 2I of insulating material. The bars 2I are rigidly connected at their lower ends by an angle cross member 23 and a cross bar 25 disposed across the opposite edges of the bars 2I from the vertical portion of the angle bar. The cross memel ber 23 and the bar 25 are clamped tightly against the support members 2| by means of bolts 2l which are disposed on opposite sides of each of the support members in order to maintain the proper spaced relation between the upright support bars.

The upper ends of the support bars 2| are spaced apart and rigidly connected by means of a casting 29 having a portion 3| integral therewith and extending transversely of the support bars. The transverse portion of the casting 29 extends beyond the upright bars 2i and is rigidly clamped thereto by means of bolts 53 disposed on opposite sides of each of the support members 2| and which cooperate with a cross bar 35 and the portion 3| of the casting 29 to rigidly secure the casting 29 to the support member 2| and to space these members apart.

The operating mechanism i3 and the trip device l are supported in a frame comprising a pair of spaced parallell side plates 3l of magnetic material which, at their left hand ends (Fig. 1), are rigidly clamped to the upright supports 2|. The right hand ends (Fig. 1) of the side plates 3l are spaced apart and rigidly connected by an angular cross member 39 secured to the side plates 3l by means of screws (il. Referring to Fig. 6 it can be seen that the side plates 3l are clamped to their respective support members 2| by clamp plates i3 disposed on the opposite sides of the support members 2| from the plates 3l, and securely held in place by bolts l5 and lll.

The plates 3l are supported at their right hand ends by an insulating block 519 (Fig. 1) which is in turn supported on a channel-shaped member 5|, the block lle being secured to the cross member 3l) by screws 53 and to the channel member 5i by screws 55. A pair of spaced angle members 5l (Figs. 1 and 3) are suitably secured, for instance by welding, to the angle cross-member 23 and to the channel member 5|, thus forming a rigid framework for supporting the operating mechanism. The entire framework is adapted to be supported on a suitable base (not shown).

The casting 29 mounted on the upper ends of the upright supports 2|, has a vertically disposed plate 59 cast integral therewith and forming a mounting for the stationary contacts of the breaker. The stationary contacts comprise a main stationary contact member 53| and a stationary arcing contact 63. The main stationary contact (5| is mounted on a block 55 of conducting material which is slidably mounted on four stud bolts 6l (only two being shown) threadedly engaging the plate 59 and extending horizontally from the face thereof. Electrically connected to the back of the block 65, and mechanically secured thereto, is a pair of flexible shunt conductors 69 each comprising, preferably, a plurality of thin, exible strips of conducting material. The flexible shunt conductors 59 are connected by means of bolts 1|, to opposite sides of a conductor i3 which is, in turn, secured by means of screws l5 to a cross member 'Il of the casting 29. A spring 19 compressed between the plate 59 and the iiexible conductor 63 provides contact pressure for the main contacts when the breaker is closed. A spring guide 8| is provided on the plate 59 to retain the spring la in place.

The stationary arcing contact (i3 is mounted on one end of a rod 83 slidably mounted in a sleeve S5 secured in the plate 59. The other end of the rod 83 is provided with a nut 8l to limit the movement in one direction of the rod 83 and the contact. A spring 8S coiled about the sleeve 85 and compressed between the plate 59 and the arcing contact provides contact pressure for the arcing contacts. A flexible shunt conductor connects the stationary arcing contact 63 to the main stationary contact 6|.

The movable contacts comprise a main movable contact 9| and a movable arcing contact 93 (Figs. 1 and 4) carried on the upper end of a pivoted contact lever pivotally mounted on a shaft 91 (Figs. 1, 3, 4 and 5) supported in the frame plates 3l. The contact lever 95 comprises a pair of levers rigidly connected at their upper ends by an integral cross member 99 to which the arcing Contact 93 is secured by means of screws mi. The main movable contact al is secured directly to the levers 535. The contact lever Sli is biased in a clockwise or opening direction by a pair of tension springs |93 (only one being shown) having one end hooked over a rod |65 mounted in the lower end of the contact lever and having their other ends anchored to spring studs il projecting from the plates 3l. The contact lever gli is also biased to open position by a pair of compression springs |99 threadedly mounted on screws and supported 0n the bracket 3S.

The contact lever 95 is releasably held in the closed contact position by a latch member ||3 which is operated by the trip device l5 upon reversal of the direction of current flow in the circuit of the breaker, to release the contact lever and permit the springs |03 and |69 to operate it to the open contact position. The latch member ||3 is rotatably mounted on a short tubular bearing H9 (Fig. 5) eccentrically surrounding the shaft 9i and supported in one end of a lever |2|. The lever |2| comprises a pair of spaced levers pivoted on a pivot pin |23 mounted in the frame plates 3l. At its other end the lever |2| carries an armature |25 pivotally supported on a pivot pin |27 mounted. in the end of the lever |2|. IThe armature |25 cooperates with an electromagnet H5 to retain the latch member ||3 in latching position as shown in Fig. 1,.

and, as will be described later, the electromagnet operates upon the occurrence of reversal of current flow in the circuit of the breaker, to release the armature. As shown in Figs. 1 and 5, the internal diameter of the tubular bearingL I9 is substantially larger than the outside diameter of the fixed pivot shaft Sl. This permits the tubular bearing H9 and the latch H3 mounted thereon to move up and down relative to the axis of the fixed shaft al. The tubular bearing H9 is disposed eccentric to the ixed shaft Sl in the closed position of the breaker s0 that this tubular bearing and the latch ||3 mounted thereon can move downwardly upon release of the lever |2| by the tripping electromagnet.

A latch member |29 (Figs. 1 and 4) is adjustably secured by means of screws |3| to a cross bar |33 connecting the two levers S5 which form the contact lever. and |99 tending to rotate the contact lever 95 clockwise, presses the lower beveled edge of the latch member |29 against the upper left hand corner of the latch member H3 and tends to move the latch member H3 in a clockwise direction about the tubular shaft HG. This rotation of the latch member H3 1s normally prevented by means of a roller |35 mounted on a pin |31 supported in a closing lever E39. It will be noted that the beveled latch surface of the latch member The force of the springs |3- |29 is inclined relatively to the longitudinal axis of the latch member I I3. This results in a downward force on the latch member, which in turn produces an upward force in armature |25. Motion of armature |25 and therefore tripping of the latch member I I3 is prevented by holding magnet ||5 until reversal of current as will be described later.

The closing lever |39 is pivotally mounted on the shaft 91 (see Fig. 5) and is connected by means of an adjustable link |4| to an operating lever |43 which is pivotally supported on a shaft |45 mounted in the frame plates 31. The upper end of the link |4| comprises an eye bolt |41 pivotally mounted on a pin |49 supported in the free end of the closing lever |39. The other end of the bolt |41 threadedly engages a yoke |5I, the two legs of which are pivotally connected to the lever |43 by means of a pivot pin |53. A downwardly extending arm |55 of the lever 43 is pivotally connected to the upper end of a vertically disposed operating link |51, the lower end of which link may be connected to a power operated closing means (not shown). The link |4| and the lever |43 form a toggle which, in the closed position (Fig. 1) is slightly overcenter to the Ileit of the center line |49-I45. In this position the force of the springs ID3-|99 transmitted through the contact lever 95, latch member ||3, the closing lever |39 and link |4I, biases the lever |43 in a counterclockwise direction against a stop screw |59 mounted in the angle member 39.

When the electromagnet I5 operates to release the armature |25, the springs IUS- |99 act to rotate the contact lever 95 clockwise to the open position (Fig. 4), and due to the beveled or inclined edge of the latch member |29 a component of the force of the springs causes the latch member ||3 to move downwardly substantially radially relative to the shaft 91 rotating the lever I2! clockwise about its pivot |23. The latch I|3 is thus disengaged from the latch piece |29 thereby releasing the Contact lever 95 from the closing lever |39 whereupon the springs |93|U9 quickly move the contact arm 95 to the open position shown in Fig. 4. The springs |99 are normally compressed between the member 39 and spring pads IIB (only one being shown) projecting laterally from the lower ends of the contact levers 95. The springs |99 serve to assist the springs |93 in moving the latch ||3 to unlatching position and in starting the opening movement of the contact lever 95. The springs |93 complete the opening movement after the springs |99 have z reached the limit of their expansion as can be seen in Fig. 4. It will be noted that the movable contacts and contact arm 95 are tripped free of the closing lever |39, i. e. the breaker will open when tripped even though the closing lever is held in closed position.

The shock of arresting the opening movement is dissipated by shock absorbers ||2, there being a shock absorber secured to the inner face of each of the frame. plates 31 engageable by the spring pads H9 as the contact lever 95 nears full open position. The shock absorbers may be of any suitable type preferably a spring biased plunger, or of any suitable resilient material.

As the contact lever 95 moves to open position the latch member |29 rides across the upper end of the latch member I3 holding the latch I|3, the lever |2| and the armature |25 in their moved position (Fig. 4). During the tripping action of the latch l| |3, the closing lever |39 is held in the position shown in Figs. 1 and 4 by the over-center condition of the toggle |5| |43.

Referring particularly to Fig. 4, the contact lever is rotated counterclockwise from its open position to the closed position by operation of the lever |43 which is accomplished by automatic closing means (not shown) but which moves the link |51 downwardly to close the contacts. Before the contacts may be closed, however, the closing lever |39 must be retrieved and relatched to the contact arm. The retrieving movement of the closing lever is effected by clockwise operation of the operating lever |43, the clockwise movement of the lever being limited by a stop |64 in the member 39.

The clockwise or retrieving operation of the lever |43 is automatically accomplished by means of a retrieving spring |66 (Fig. 1) having one end attached to the member 51 and the other end attached to the link |51. The spring |66 biases the link |51 upwardly and biases the lever |43 in a clockwise direction, however the tension of the spring |95 is not sulicient to move the toggle |4I--I43 overcenter against the force of the springs |93-|99. When the latch |I3 is moved downwardly to release the contact lever 95 the pressure of the springs HB3- |99 is no longer applied to the toggle |4I--I43 whereupon the spring |99 moves the link |51 upwardly and rotates the lever |43 clockwise until it is arrested by striking the stop |94. During the clockwise movement of the lever |43 the toggle |4I-I43 is moved overcenter to the right of the line I45|49 to a collapsed position thus rotating the closing lever |39 clockwise from the position in which it appears in Figs. 1 and 4. As the closing lever I 39 is rotated clockwise, a cross pin |65 thereon engages the left hand edge of the latch member |I3 and rotates the latch member therewith until it clears the latch member |29 whereupon the magnet I I5 attracts the armature |25 rotating the lever |2| counterclockwise and thrusts the latch member I3 upwardly into latching engagement with the latch member |29.

After the latch I |3 is reengaged with the latch |29 it is held in its engaged position by the magnet l5 which is energized through the agency of the holding coil |1, the holding coil ||1 being energized independently of the current in the circuit of the breaker. The breaker may now be closed by rotating the lever |43 counterclockwise through the agency of the link |51 and the closing mechanism (not shown) to its position against the stop |59 (Figs. l and 4). This movement of the lever |43 straightens the toggle |4|| 43 and rocks the closing lever |39 counterclockwise. rhis movement of the closing lever acting through the roller |35 rotates the latch member ||3 and the contact lever 95 counterclockwise to close the contacts and tension the springs ID3-|09.

Manual opening or tripping of the breaker may be accomplished by opening the energizing circuit of the holding coil 293.

The electromagnet ||5 (Figs. l, 2 and 4) comprises a plurality of laminated core members |51 each of which is provided with an air gap |69 (Fig. 2) and a smaller air gap |1| The air gaps |69 of the core members |61 are disposed alternately on the upper right and left hand corners as indicated in Fig. 2. The core members |61 are suitably secured together to form a unitary core for the magnet ||5, and are also secured to end brackets |13 which are mounted between the frame plates 31 by means of bolts |15. Each of the core members |97 is provided with a centrally located opening |77 (Fig. 2) through which passes a conductor comprising a pair of parallel conductors |79 forming a part of the electrical circuit of the breaker. At its left hand end the conductor |79 is mechanically and electrically connected by means of bolts |89 to the inner end of a terminal connector |8|, and the right hand end (Figs. 1 and 4) of the conductor |79 is suitably connected, for instance by brazing to a yoke |93 (Figs. 1, 4 and 5) of conducting material. The yoke |93 has upwardly extending legs |85 (Fig. 5) each provided with an opening through which passes a sleeve |97 surrounding the shaft 97 (see Fig. 5) and having inner flanged ends disposed between the closing lever |99 and the legs |95. The legs |85 of the yoke |83 are disposed adjacent the inner sides of the contact levers 95 and are held in intimate contact with said levers by means of nuts |89 threaded onto the outer ends of the sleeves |97 and having spring Washers |9| disposed between the outer faces of the levers and said nuts |99. Each yof the nuts |89 is provided with a set screw |93 for locking the nuts in position after they have been rotated on the threaded portions of the sleeves |97 to provide the proper pressure contact between the legs |95 of the conductor yoke |93 and the contact levers 95.

The electrical circuit extends from the termix sufficient flux in the magnetic circuit to hold the armature |25 in attracted position. The holding coil |7 comprises a core member |97 (Fig. 6) of magnetic material having one end threaded as at |99 to receive a nut 29|, also of magnetic material, and an energizing coil surrounding the core member. After the coil 293 and the nut 29| are assembled on the core member |97, the assembly is inserted between the magnetic frame plates 97 adjacent the support bars 2| (Figs. 1 and 6) and a retaining bolt 295 is inserted through openings in the support bars 2|, the frame plates 37 and the core member. The nut 29| is then rotated in a direction to force the end of the core member |97 and the nut into intimate contact with the adjacent frame plates 57. Nuts 297 0n the threaded ends of the retaining bolt 295 are then tightened to retain the holding magnet assembly in place. It will thus be seen that the trame plates 37 form a part of the path for the magnetic ilux of the holding magnet i i7, the iiux passing through the core member |97, one of the frame plates 37, the core members |97 and armature |25 of the magnet H5, and through the other frame member 37 back to the core member |97.

When the current is owing in the proper direction in the circuit of the breaker including the conductor |79, the magnetic flux produced by the holding coil ||7 in the magnetic circuit and through the core members |97 and armature |25 is in the same direction as the magnetic flux generated in the trip magnet by the conductor |79. However, when the direction of current flow in the breaker circuit is reversed the magnetic flux of the .trip magnet |5produced by 8 the conductor |79 reverses its direction. The holding flux between the armature |25 and the magnet H5 is thus reduced to such a value that the armature is released and the springs |93|99 move the contact lever to open position.

The nut 97 on the left hand end of the arcing contact rod 83 (Fig. 1) is spaced slightly to the left of the portion 59 of the casting 2.9 in the closed position of the contacts so that when the Contact lever 95 moves to open the contacts, the main contacts Eil-9| will rst separate and then, a very short time later, the arcing contacts 63-93 will open drawing the arc between the arcing contacts. The arc resulting from the ow of the current after the contacts have separated is drawn into the arc extinguisher |9 by means of the blow-out magnet |7 Where it is extinguished. The blow-out magnet comprises the coil |94, connected in series relation in the circuit of the breaker, and a U-shaped core member 299 of magnetic material supported on the casting 29 and insulated from the coil |94. The legs of the core members 299 are supported by vertically disposed insulating bars 2| having their upper ends secured by means of screws 2|.3 to the legs of the core member 269, the lower ends of the support bars 2| being supported on the frame plates 37 and secured thereto by screws 2 I5.

The arc extinguisher is of the slotted plate type and the current of the arc drawn thereinto is shunted around the contacts and the breaker operating mechanism to the terminal connection |S| by means of a shunt circuit shown in part at 2|7 (Figs. 1, 3 and 6). rThis prevents the iiow of current through the various pins, bolts and latches, which might damage them.

The arc extinguisher is preferably of the type fully disclosed and claimed in United States Patent No. 2,242,905, issued May 20, 1941, to R. C. Dickinson and R. H. Nau, and assigned to the assignee of the instant invention.

From the foregoing description it will be apparent that there is provided an improved circuit breaker of novel construction which is operated to open position at high speed in response to abnormal conditions and in which the contacts are trip free of the closing means. It will also be seen that the trip device comprises a holding magnet having a magnetic circuit which includes the frame members for supporting the breaker operating mechanism.

Having described the preferred embodiment of the invention in accordance with the patent statutes, it is to be understood that various changes and modications may be made in the structural details disclosed without departing from some of the essential features of the invention. It is, therefore, desired that the language of the appended claims be given as reasonably broad interpretation as the prior art permits.

We claim as our invention:

1. In a circuit breaker, relatively movable contacts, a switch member mounted on a iixed pivot and movable to open and close said contacts, operating mechanism for said switch member including an operating member operable to eiect closing movement of said switch member, a latch member having its free end interposed between the switch member and the operating mem-ber for connecting said switch member to said operating member, said latch being supported independently of said operating member and said switch member, a trip device including electroresponsive means normally restraining said latch in latching position and being operable in yre- 9 sponse to predetermined circuit conditions to cause said latch to be moved to unlatching position to thereby effect opening of said contacts.

2. In a circuit breaker, relatively movable contacts, a switch member mounted on a fixed pivot and movable to open and close said contacts, operating mechanism for said switch member including an operating member movable to eiect closing movement of said switch member, means interposed between said switch member and said operating member for releasably restraining said switch member in closed position, said means being supported independently of said members, a holding electromagnet structure for holding the restraining means in restraining position, said holding electromagnet being operable in response to predetermined circuit conditions to permit longitudinal movement of the restraining means to a. non-restraining position to thereby permit opening movement of the switch member, and said restraining means being operable by said operating member to move the switch member to closed position.

3. A circuit breaker comprising relatively movable contacts, a switch member movable to an open and to a closed position to open and close said contacts, operating mechanism for said switch member including a member pivoted coaxially with said switch member operable to efrect closing movement of the switch member, means for restraining said operating member in closed position, a member supported independently of said operating member and extending between the switch member and the operating member for normally connecting the switch member to said operating member, and a holding magnet for holding said connecting member in connecting position, said holding magnet being operable in response to predetermined circuit conditions to permit movement of said connecting member from between the switch member and said operating member to permit opening movement of the switch member irrespective of the position of the operating member.

e, A circuit breaker comprising relatively movable contacts, a switch member pivoted on a fixed pivot biased to open position and operable to open and close said contacts, operating mechanism for said switch member including a lever movable to effect closing operation of said switch member, a latch member supported separately from said switch member and said operating lever and eX- tending between said lever and said member for releasably connecting the switch member to the operating lever, said latch being biased to unlatching position, means including an electromagnet for holding said latch member in latching position, said holding electromagnet being operable in response to predetermined circuit conditions to permit movement of said latch member to unlatching position to effect o-pening movement of the switch member.

5. A circuit breaker comprising relatively movable contacts, a switch member biased to open position and movable to open and close said contacts, operating mechanism for said contacts including a member operable to elect closing of said contacts, a pivot-ally and longitudinally movable latch member having its free end disposed between the switch member and said operating member for releasably connecting said switch member and said operating member, means operable in response to predetermined circuit conditions to cause withdrawal of the latch member 10 to effect opening movement of said switch member.

6. A circuit breaker comprising relatively movable contacts, a switch member movable to open and close said contacts, operating mechanism for said switch member including a lever for operating said switch member to closed position, a latch member connecting the switch member to the operating lever to releasably restrain said switch member in closed position, means for pivotally supporting said latch member, said support means being operable in response to reversal of current in the circuit to effect longitudinal movement of said latch member to release said switch member, and said latch member being pivotally movable with said operating lever to effect closing movement of said switch arm.

7. A circuit breaker comprising relatively movable contacts, a pivoted switch arm movable to open and close said contacts, operating mechanism for said switch arm including an operating lever pivoted coaxially with said switch arm and operable to effect movement of said switch arm to closed position, a movable latch having an end interposed between said switch arm and said operating lever to releasably connect said switch arm and said operating lever, means independent of said switch arm and said operating lever for supporting said latch for longitudinal movement to an unlatching position means biasing said switch arm to open position and biasing said latch to unlatching position, and a holding magnet for holding said latch in latching position and operable in response to reversal of current in the circuit to permit said biasing means to move said latch to unlatching position and to move said switch arm to open position.

8. A circuit breaker comprising relatively movable contacts, a switch arm biased to open position and movable to open and close said contacts, an operating member, a pivoted latch having its free end normally interposed between said switch arm and said operating member for restraining said switch arm in closed position, means supporting said latch independently of said switch arm and said operating memb-er, a holding magnet for holding said latch in restraining position, said holding magnet being operable in response to predetermined circuit conditions to release said latch, means on said switch arm for moving said latch longitudinally from its position between said switch arm and said operating member, means to operate said operating member to eiect pivotal resetting movement of the latch, said holding electromagnetic means actuating said latch to its position between said switch arm and said operating member while said switch arm is in open position.

9. A circuit breaker comprising relatively movable contacts, operating means therefor, a member interposed between the operating means and the movable contact to restrain said movable contact in closed position, a frame for supporting said operating means, a trip device including a trip member for pivotally supporting said restraining member, and electromagnetic means for holding said restraining member in restraining position and operable in response to predetermined circuit conditions to permit longitudinal movement of said restraining member from between said operating means and said movable contact, said supporting frame forming a part of said electromagnetic means,

10. In a circuit breaker comprising a supporting frame for supporting the breaker mechanism,

relatively movable contacts and operating mechanism for said contacts, a trip device including a latch member connecting the movable contact and said operating mechanism for restraining said movable contact in closed position, a trip member for pivotally supporting said latch member and operable to permit longitudinal movement of said latch member to a non-restraining position, and electromagnetic means including said supporting frame for holding said trip member against tripping movement, said electromagnetic means being responsive to predetermined circuit conditions to release said trip member.

11. In a circuit breaker including spaced supporting frames of magnetic material for support ing the breaker mechanism, a trip device including a latch member operable to eiiect opening of the breaker, a trip member for pivotally supporting said latch member and operable to actuate said latch in a longitudinal direction to a nonlatching position, an electromagnet for holding said' trip member against tripping movement and operable in response to reversal of current in the circuit to release said trip member, said electromagnetic having a magnet core mounted between said spaced supporting frames, and a holding electromagnet having a core member mounted between said spaced supporting frames for energizing said rst named electromagnet, said supporting frames forming a part of the magnetie circuit for said holding electromagnet.

l2. In a circuit breaker, the combination of relatively movable contacts, a pivoted switch member biased to open position and movable to open and close the contacts, an operating meniber pivo-ted coaxially with said switch member and operable to effect movement of said switch member to closed position, a latch connecting the switch member and said operating member to releasably restrain said switch member in closed position, a trip member for supporting said latch for pivotal and longitudinal movement relative to said switch member, and an electromagnet for holding said trip member and said latch in restraining position, said holding electromagnet being operable upon reversal of current in the circuit of the breaker to permit longitudinal movement of said latch to effect opening movement of the switch member.

13. In a circuit breaker, the combination of a pivoted switch member movable to open and closed positions, operating mechanism for said switch member including a lever pivoted coaxially with said switch member and operable to move said switch member to closed position, a `trip device including a trip lever, a latch' member pivo-tally supported on said trip lever and having one end interposed between said switch member and said lever for normally connecting said switch member and said operating lever to restrain said switch member in closed position, and a holding electromagnet including an armature carried by said trip lever for holding said latch in connecting position, said holding electromagnet being operable in response to reversal of current in the circuit of the breaker to release said armature and permit longitudinal movement of said latch to release the switch member.

14. In a circuit break-er, the combination oi relatively movable contactsJ a pivoted switch arm movable to open and close said contacts, an operating member pivoted coaxially with' said switch arm and operable to move said switch arm to close the contactsy a latch pivoted eccentrically of said switch arm and said operating member for normally connecting said switch arm and said operating member, a trip member supporting said latch for rotary and substantially radial movement relative to the pivot ci said switch arm and said operating member, and electroresponsive means operable in response to predetermined circuit conditions to eiect radial movement of said latch to disconnect said switch arm from said operating member irrespective of the position of said operating member.

l5. A circuit breaker comprising relatively movable contacts, a switch member movable to open and close said contacts, operating mechanism for said switch member including a. member operable to effect movement of said switch member to closed position, a latch' member having one of its ends interposed between said switch member and said operating member to releasably connect said switch member and said operating member, biasing means at all times biasing said switch member to open position, auxiliary biasing means for biasing said switch member in opening direction during at least a. portion of the opening stroke, and a holding magnet for restraining said latch in latching position and operable to permit said biasing means to move the latch longitudinally to unlatching position and to move said switch member to open position.

16. A circuit breaker comprising relatively movable contacts, a switch member movable to open and close said contacts, operating mechanism for said switch member including a member operable to eiiect movement of said switch member to closed position, a latch member interposed between said switch member and said operating member to releasably connect said switch member and said operating member, spring means biasing said switch member in opening direction and biasing said latch to unlatching position, said spring means being operable to move said switch arm to full open position, auxiliary spring means biasing said switch member in opening direction and biasing said latch in unlatching direction at least during the unlatching portion of the opening movement of said switch member, and a holding magnet for holding said latch in latching position and operable to permit said biasing means to move said latch to unlatching position and to move the switch member to open position.

17. A circuit breaker comprising relatively movable contacts, a switch member movable 'to open and close said contacts, operating mechanism for said switch member including a member operable t0 effect closing movement of said switch member, means interposed between the switch member and said operating member for releasably restraining said switch member in closed position, means biasing said switch member to open position, said biasing means acting through' said switch member to bias said restraining means to a non-restraining position, and a holding magnet for holding said restraining means in restraining position and operable to permit said biasing means to move said restraining means to non-restraining position and to move said switch member to open position, a, part of said biasing means being eiective to bias said switch member to open position only during a portion of the opening movement of said switch. member.

18. In a circuit breaker, the combination of a pivoted switch member movable to open and closed positions, means biasing said switch member to open position, operating mechanism for 13 said switch member including a lever pivoted coaxially with said switch member and operable to move said switch member to closed position, a trip device including a tripping lever pivoted at a point spaced from the axis of rotation of said closing lever, a latch rotatably mounted on said tripping lever about an axis adjacent the axis of said operating lever, means connecting said latch for movement with said operating lever, a latch element on said switch member engageable by said latch to connect said switch member and said operating lever, the engaging surfaces of said latch element and said latch being disposed so ROBERT C. DICKINSON. WILLIAM H. STUELLEIN. FRITZ E. FLORSCHUTZ.

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