US2354135A

US2354135A - Motor operated circuit breaker

Info

Publication number: US2354135A
Application number: US391243A
Authority: US
Inventors: John W May
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1941-05-01
Filing date: 1941-05-01
Publication date: 1944-07-18
Anticipated expiration: 1961-07-18

Description

July 18, 1944. J. w MAY MOTOR OPERATED CIRCUIT BREAKER Filed May 1, 1941 4 Sheets-Sheet l INVENTOR John WMay.

@( *g mo Y July 18,1944. J w, MAY 2,354,135 I MO TOR OPERATED CIRCUIT BREAKER Filed May 1, 1941 4 Sheets-Sheet 5 WITNESSES: INVENTOR I WM John W May.

July 18, 1944. MAY 2,354,135

MOTOR OPERATED CIRCUIT BREAKER I Filed May 1-, 1941 4 Sheets-Stieet 4 WITNESSES; INVENTOR Jab/7 W Ma Patented July 18, 1944 MOTOR OPERATED CIRCUIT BREAKER,

John W. May, Pittsburgh, Pa., assignor toWestinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application May 1, 1941, Serial No. 391,243

11 Claims.

The invention relates to circuit breakers, and more particularly to trip-free air circuit breakers of the type which are operable by an electric motor and which also have provision for manual operation.

The prior art motor operated circuit breakers of which I am aware are more complicated and expensive than is desired. On standard type motor operated circuit breaker disclosed in Patent No. 2,228,466, issued to Leon R. Ludwig and Ture Lindstrom, January 14, 1941, embodies a relatively complicated and expensive clutch arrangement for coupling the circuit breaker mechanism to the motor unit, disengagement of the clutch being required before the circuit breaker can be manually operated. Moreover, the circuit breaker mechanism requires a special resetting operation by the motor before the breaker can be reclosed after a tripping operation.

Another standard type of motor operated circuit breaker disclosed in the copending application of Ture Lindstrom, Serial No. 156,743, filed July 31, 1937, which became Patent No. 2,240,656 on May 6, 1941, embodies a main operating toggle, one end of which is held by a latching means. A translatable closing lever connected to the knee of the toggle is adapted to be moved to close the breaker by a motor driven crank arm. A second similar lever connected to the knee of the toggle is engageable by a second rotatable crank arm L which is manually operable by a handle on the side of the breaker for manually closing the breaker.

Although the above described types of circuit breakers operate satisfactorily, they are more complicated and expensiv to manufacture than is desired for some applications.

An object of the present invention is the provison of an improved motor-operated trip-free circuit breaker of simple and inexpensive construction.

Another object of the invention is the provision of an improved motor-operated circuit breaker embodying a very simple trip-free circuit breaker mechanism without any latching means and which automatically resets itself after tripping so that the motor unit only functions to close the breaker and is not required to reset the mechanism.

An other object of the invention is the provision of an improved motor operated trip-free circuit breaker having a movable operating member operated by the motor to close the breaker, the same operating member also being operable manually without interference by the motor operating unit and without disengaging any levers o-r clutches.

Another object of the invention is the provision of a motor-operated trip-free circuit breaker having an operating toggle actuated by an operating lever pivoted on a fixed support and movable to close the breaker either by a motor-operated crank arm or .by manual means, the crank of the motor unit being arranged to stop in a position clear of the operating lever after closing the breaker.

Another object of the invention is the provision of a motor-operated circuit breaker as described in the preceding paragraphs furthercharacterized by the feature that the motor-operated crank arm is arranged to make anangle of substantially with the operating lever at the time the breaker reache closed position and also cooperates with the action of the operating toggle so as to provide a mechanical advantage which increases during closing of the breaker and becomes a maximum at the time the breaker reaches closed position.

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

Figure 1 is a fragmentary front elevational view of a motor-operated circuit breaker constructed in accordance with the invention,

Fig. 2 is a fragmentary vertical sectional view of the circuit breaker taken substantially along the line II-II of Fig. 1, the circuit breaker being shown in the closed circuit position,

Fig. 3 is a View similar to Fig. 2 showing the circuit breaker in tripped open position an instant after operation of the trip device and before the mechanism has been automatically reset,

Fig. 4 is a view similar to'Fig. 2 but showing the circuit breaker in open position with the motor-operated crank in an instantaneous position where it is just starting to close the circuit break- Fig. 5 is a diagrammatic view illustrating a portion of the motor energizing circuit, and

Fig. 6 is a fragmentary sectional View through the motor housing at the line VI-VI of Fig. 2, to illustrate the centrifugal brake for stopping the motor and crank arm.

Referring to the drawings, the three-pole cir cuit breaker illustrated comprises a base 1 of insulating material upon which is mounted three stationary contact means 9, three cooperating movable contact means II, the arc extinguishers It, a common operating mechanism l5 and a trip device IT.

The three stationary contact means 9 and the three movable contact means H cooperate to form the several poles of the breaker and are disposed side by side on the base I.

The stationary contact means 9 for each hole of the breaker comprises a stationary main contact l9 and a stationary arcing contact 2| which are electrically connected to a corresponding terminal (not shown) mounted at the upper end of the base 7. The movable contact means ll of each pole of the circuit breaker comprises a main movable contact 23 secured to a pivoted contact arm 25 of conducting material, and a movable arcing contact 21 secured to an upwardly extending offset projection 29 of the contact main stationary contact I9, the cooperating main 2 movable contact 23, the contact arm 25 and through the flexible shunt conductor 3| to the lower terminal 33.

The assemblage of the movable contact means I! is pivoted to a U-shaped frame of the operating mechanism l5 by means of a pivot pin 31. A tie bar 39 serves to mechanically connect the three movable contact means H for movement together about the common pivot 31. As shown in the drawings, each contact arm 25 is pivoted by a pivot pin 4| to a clamp member 43 which engages the steel tie bar 39, the bolts 45 being provided as the fastening means. A square tube 41 of insulating material is positioned between the tie bar 39 and the clamp members 43 to electrically insulate the poles from each other. Springs 49 are provided for biasing each of the contact arms 25 toward the cooperating stationary contact means 9 with a predetermined normal force. Counterclockwise movement of each contact arm 25 relative to its clamp member 43 is limited by the lower end of the contact arm 25 coming into engagement with a portion of the clamp member 43, as shown in Fig. 3, when the circuit breaker opens.

The construction of the movable contact means i is such that the movable arcing contact 21 engages the stationary arcing contact 2| before the main contacts separate during the initial portion of the circuit opening operation, and the arcing contacts 27-2l separate after the main contacts as the circuit breaker moves toward open circuit position so arcing takes place only between the arcing contacts. The sequence of operation of the contacts during closing is substantially the reverse of the opening sequence, the arcing contacts 2'|2| engaging prior to the engagement of the main contacts as the circuit breaker approaches closed position and remain in engagemerit until the main contacts become engaged.

Th clamp member 43 of the center pole of the circuit breaker has a bifurcated section 5| formed integral therewith and provided with openings for engaging the main pivot pin 31, openings for engaging a pivot pin which connects the section to the operating mechanism 5, and elongated openin 53 for clearing the fixed pivot pin 55 of the U-shaped operating lever 5'! which forms a part of the operating mechanism 5. The

pivot pins

31 and 55 extend between the side walls of the frame 35 and are supported thereby.

The central clamp member 43 and its integral section 5| form the switch arm for the movable contact assemblage carried thereby. The sides of the U-shaped operating lever 51 which engage the fixed pivot 55 are disposed inside of the side walls of the mechanism frame 35, and th bifurcated section 5| of the central clamp member is nested between the sides of the U-shaped operating lever 51. Clockwise or opening movement of the switch arm 5| and the movable contact means carried thereby is limited by the engagement of the central clamp member 43 with a pair of inwardly ofiset projections 59 of the mechanism frame 35. The projections 59 also limit the counterclockwise or closing movement of the operating lever 51. The clockwise movement of the operating lever 51 is limited by a pair of stop lugs 5|) extending inwardly from the sides of the frame 35, these lugs determining the open position of the operating lever.

The flexible shunt conductor 3| for the center pole of the circuit breaker passes between the side walls of the frame 35 and is insulated from the frame by a lining 62 of insulating material on the inside of the frame.

The are extinguishers |3 may be of any suitable type. One satisfactory type of arc extinguisher which may be used is disclosed in Patent No. 1,896,764, issued to M. W. Brainard February 7, 1933, and assigned to the assignee of this invention.

The operating mechanism |5 of the circuit breaker includes the pivoted operating lever 51 and an operating toggle comprising a pair of toggle links 6| and 63 pivoted together by a knee pivot pin 65. The toggle link 6| consists of a double link formed of a single piece of metal and has its upper end pivotally connected to the switch arm 5| by a pivot pin 61. The lower end of the operating toggle, that is the lower end of the toggle link 63 which is also a double link, is pivotally connected to a linkage indicated generally at 69 which will be hereinafter described. The linkage 69 serves to normally hold the lower end of the operating toggle in a fixed operative position, as shown in Figs. 2 and 4, so that the operating toggle is capable of transmitting the closing thrust of the operating lever 51 to the switch arm 5| to close the breaker and also to hold the circuit breaker in closed position after it has been closed.

The switch arm 5| and the three movable contact means i i carried thereby are biased to open circuit position by means of a circuit opening spring 7|, one end of which is anchored to a pin '53 supported by the frame 35. The outer end of the circuit opening spring H is connected to the central portion of the pivot pin 61.

The operating toggle 5|63 is adapted to be moved to a slightly overset position, as shown in Fig. 2, by movement of the operating lever upwardly about its pivot 55 to closed position, thereby effecting closing of the circuit breaker contacts. Movement of the operating toggle beyond the overset position shown in Fig. 2 is prevented by stop projections 14 on the link 6| which engage a stop pin carried by the lower toggle link 63. The operating lever 51 is connected to the operating toggle by means of a connecting link 71, one end of which is pivotally connected to the lower end of the operating lever by a pivot pin E9. The other end of the connecting link 1'! is provided with a slot 8| which engages the stop pin 15 and provides a slight lost motion connection between the operating lever 51 and the operating toggle. The connecting link Ti and its slot 8| permit the circuit breaker to be tripped free of the operating lever 51 and also serve to break the operating toggle during a tripping operation.

A coil spring 80 mounted on the fixed pivot 55 is provided for the purpose of restraining the operating lever 51 in closed positionto prevent the weight of the lever from bearing on the knee of the operating toggle 6I-63. This spring prevents the operating toggle from being falsely collapsed upon the occurrence of shocks or jarring forces applied to the circuit breaker. The spring 80 is relatively weak, however, so that it will not prevent automatic movement of the operating lever 51 to open position when the circuit :breaker is tripped.

Th linkage 69 which normally holds the lower end of the operating toggle in fixed operative position, includes a link or lever 83 pivoted at its lower end on a fixed pivot pin 85 supported by the frame 35 and having its upper end pivotally connected to the lower end of the toggle link 63 by a pivot pin 81. The linkage 69 also includes a toggle comprising a relatively long U- Shaped link 89 pivoted at its inner end on a fixed pivot pin 9I supported by the frame 35, and a short toggle link 93 disposed inside of the link 89 and connected thereto by a pivot pin 95. The other end of the link 93 of the inverted toggle is pivotally connect-ed to the pivot pin 8'! which connects the link 83 to the lower end of the operating toggle. I

When the breaker is in closed circuit position, the operating toggle 6 I83 is in its slightly overset position in which the knee. pivot pin. 65 is disposed slightly to the right of a center line A joining the

shafts

61 and 81. The links BI and 63 with thestops "resting against the pin .15 acts as a single link in this position, which in combination with the link 83 forms a second toggle with its knee at the pivot '81. This second toggle also occupies a slightly overset position in which the knee pivot 81 thereof is to the right of center line B connecting the pin centers 61 and 85.

The inverted toggle 89-93 normally occupies a slightly overset position in which the pivot pin 81 is disposed slightly above a center line C joining the pivots 9| and 95. This position of the holding toggle is determined by an adjusting screw 91 which is mounted on a lateral extension 96 of one of the sides of the frame 35, F

the outer end of the toggle link 89 bearing against the adjusting screw 91. The opening bias of the circuit breaker produced by the circuit opening spring H is transmitted through the operating toggle 6I63 to the pivot pin 81 and urges the link 83 in a clockwise direction about the fixed pivot 85. Movement of the supporting link .83 in a clockwise direction is normally prevented; however, by the holding toggle 89--93 due to its overset position. The major portion of the opening bias of the circuit breaker is carried by the fixed pivot 85 and only a relatively small component thereof is transmitted to the holding toggle 89-93. This provides the advantage that only a relatively small tripping force is required to cause opening of the circuit breaker despite the large opening forces involved. The holding toggle 89-93 is maintained in engagement with the screw 85 by the small component of the opening bias of the circuit breaker, and the pivot 81 of the lower end of the toggle cannot be moved in a clockwise or tripping direction about the pivot 85 until the holding toggle is moved over centerby the trip device I1.

eration of the circuit breaker.

purpose of automatically resetting the breaker mechanism. to operative position following each opening operation of the circuit breaker. One end of the retrieving spring I00 is anchored to a stud I02 carried by the long toggle link 89 ad jacen't the pivot thereof, and the other end of the spring is connected to the link 83. The sprin'g'l 80 serves to automatically reset the lower endofthe operating toggle and the linkage 69 to normal position following each tripping op- The spring I also acts to insure complete collapse of the operating toggle and cause movement of the operating lever 51 to open position during a tripping operation of the circuit breaker.

Th trip device I1 comprises a trip plunger I03, and an electromagnet having a core I05, apivoted armature I81 and an energizing winding IE9. The trip plunger IE3 is pivotally connected to the armature I01 by a pivot pin III, and the armature is pivoted to one leg of the core I85 by a pivot pin H3. The trip plunger I83 extends upwardly through a. guide opening in the lateral extension i8 of the frame and the plunger m3 is adapted to be moved upwardly to engage and cause collapse of the holding toggle, 8993 when the electromagnet is energized to thereby cause opening of the circuit breaker.

The energizing winding I219 of the electromagnet may be arranged as a shunt trip to be energized either by fault responsive relays in response to an abnormal condition in the circuit controlled by the breaker or by a shunt control circuit from a remote point, in a manner well known in the art. If desired, however, the

trip plunger may be operated by any one of a A cross pin H9 is carried by the upper end of the trip plunger above the lateral projection 98 of the frame 35 for the purpose of limiting downward movement of the trip plunger. The trip plunger I03 has a threaded portion which threadedly engages the bracket Ill and provides a means for adjusting the air gap between the armature I0! and core I05. The trip plunger 13 is adjusted to a position such as to provide a sufiicient air gap between the armature I 8,1

and the magnet core I05 when the trip plunger. touches the holding toggle to insure that the plunger will'be moved upwardly a sufiicient distance. to cause collapse of the holding toggle Bil -53 when the armature I0! is moved to fully attracted position.

.The operation of thecircuit breaker mechanism as thus far described is briefly as follows: Assuming the circuit breaker to be in the closed circuit position shown in Fig. 2, to manually open the circuit breaker the operating lever 5! moved in a clockwise direction about its pivot to its open position. This movement of the operating lever is transmitted to the operating toggle 6I63 by the connecting link 1! and causes collapse of the operating toggle inwardly toward the base I. The circuit opening spring 1| quickly moves the switch arm 5| and the movable contact means II carried thereby to open circuit position as soon as the knee pivot 65 of the operatin toggle crosses to the left of the center line A. During this manual circuit opening operation, the lower pivot 81 of the operating toggle remains in fixed operative position where it is held by the linkage 69. The linkage 69 is held in its normal position by the spring I99 when the breaker is open. Downward or clockwise movement of the operating lever 51 is limited by the stop 69.

To manually close the circuit breaker, the operating lever 51 is moved in a counter-clockwise or upward direction about its pivot 55 to the closed position shown in Fig. 2. This movement of the operating lever is transmitted to the operating toggle 6I63 by the link 11 and moves the toggle to the overset position causing movement of the switch arm 5| and the three movable contact means I I to closed position against the force of the circuit opening spring II. The circuit breaker is retained in closed circuit position by reason of the overset position of the toggle links ISL-93 and 83 as long as the pivot 31 is held in fixed operative position by the holding toggle 8993. The torsion spring 89 maintains the operating lever in closed position against the stops 59 so that the weight of this lever does not bear against the operating toggle.

The circuit breaker is automatically operated to open circuit position upon operation of the trip device l1. When the winding I99 of the electromagnet is energized either in response to predetermined abnormal conditions by the fault responsive relays or by the shunt control circuit, the armature lever I91 is moved to attracted position and causes upward movement of the trip plunger I93. The trip plunger when moved upwardly engages the outer end of the holding toggle 89-93 and moves this end upwardly until the pivot 95 crosses above a line through the centers of the pivots 9i and 81, whereupon the holding toggle no longer restrains the pivot 81 in operative position. The opening force of the circuit opening spring II is transmitted through th operatin toggle 8I-63 to the pivot 81 and moves the pivot 81 and lever 83 in a clockwise direction about the fixed pivot 85 to tripped position as shown in Fig. 3, causing collapse of the holding toggle 8993. The switch arm 5I and movable contact means II carried thereby are moved to open circuit position by the circuit opening spring 1! and the toggle links 6I-63 are moved downwardly as the link 83 moves to tripped position. During this circuit opening movement, the pin on the link 53 engages the outer end of the slot 8i of the connecting link 11, and since the operating lever 51 cannot move any further in a counter-clockwise direction, the link 11 acts to cause collapse of the operating toggle 6I--63. As soon as the switch arm 5! reaches open circuit position as determined by the stop portion 59 of the frame 35, the retrieving spring I99 automatically resets the link 83 and holding toggle 89-43 to the normal holding position as shown in Fig. 3. The operating lever 51 is also moved downwardly to open position during tripping operation. of the breaker. This movement of the operating lever 51 is initiated as soon as the operating toggle 6 I-ES begins to collapse and is completed by the resetting action of the retrieving spring I99 which aids in completing the collapse of the operating toggle. The torsion spring 89 is of insufiicient strength to interfere with this movement of the operating lever to open position. The parts of the circuit breaker now occupy the open position illustrated in Fig. 4 of the drawings, and the circuit breaker may be reclosed by movement of the operating lever 51 in a counter-clockwise direction to the closed position shown in Fi 2.

It will be noted that the circuit breaker is trip free of the operating lever 51. In other words, the contacts will be automatically operated to open circuit position upon operation of the trip device I1, irrespective of the position of the operating lever 51, that is, even though the operating lever may be held in closed position. In addition to being trip free, the mechanism possesses the important advantage that it does not embody any latching means, the linkage 69 constituting the sole means for holding the lower end of the operating toggle in a fixed operative position. Another very important advantage of the mechanism is that it automatically resets itself following each tripping operation, and the operating lever 51 is automatically moved to open position so that the mechanism is immediately ready to reclose the breaker without requiring any special resetting movement of the operating lever.

The contact assemblage, the operating mechanism and the shunt trip device of the circuit breaker are of substantially the same construction as disclosed in the aforementioned copending joint application of Ture Lindstrom and myself filed concurrently with this application.

The circuit breaker is adapted to be operated to closed circuit position by a motor operating unit indicated generally at I2 I. The motor operating unit has a housing I23 provided with an integrally formed mounting plate I25 by which the unit is mounted on the circuit breaker mechanism frame 35. The mounting plate I25 is removably secured to one of the side walls of the U-shaped mechanism frame 35 by means of a plurality of bolts I21 which engage in openings provided in the side wall of the frame to correctly position the motor operating unit I2I relative to the operating lever 51.

An electric driving motor of the universal type indicated by the reference numeral I29 is mounted within the lower portion of the housing I23. The upper portion of the housing I23 is formed to provide a gear casing I3I, and an extension of the armature shaft of the motor I29 projects into the gear casing I3I. Upon this extension is secured a worm I33 which engages a worm gear I35. The worm gear I35 is secured for rotation with a counter-shaft I31 rotatably mounted in suitable bearings provided in the gear casing. One end of the countershaft I31 extends through a side of the gear casing and has a crank arm I39 rigidly secured thereon. The free end of the crank arm is provided with a crank roller I4I which is disposed to engage an extension I43 secured to the operating lever 51. The crank arm I39 is adapted to engage the extension I43 of the operating lever 51 and move the operating lever from open to closed position when the crank arm is rotated through a cycle by the driving motor I29.

The electric motor is provided with a control circuit for energizing the sam to effect a closing operation of the circuit breaker. A portion of the motor energizing circuit I45 is illustrated in Fig. 5 of the drawings. Included in series in the energizing circuit I45 of the motor is a manually operable control switch I41; and an auxiliary switch I49 which is operated by the movable switch arm SI of the circuit breaker. The auxiliary switch I49 may be of any conventional construction and is arranged to be closed when the circuit breaker is open and to be opened when the circuit breaker is closed so that whenthe manual control switch I4I is closed, andthe breaker is open thesmotor will be energized andstart rotation of the crank arm I39.

A rotary switch I5 I operated by the shaft I31 of the crank arm, is connected in parallel with the auxiliary switch I49 for the purpose of continuing the energization of the motor after the auxiliary switch opens and until the crank arm has closed the breaker and moved out of the way of the oper ating lever extension I43, Since the crank arm is thus stopped in a position clear of the operating lever it allows the operating lever to be moved to open position upon tripping of the circuit breaker. This arrangement also permits manual operation of the operating lever without interference by the motor operating unit. The rotary switch includes a contact segment I53 secured to an insulating drum I54 on the crank shaft I31, and a pair of spring contact fingers I55 mounted on an insulating support I51 in the gear casing I3I.

The spring contact fingers I55 are electrically connected to the terminals of the auxiliary switch I49 so as to connect the rotary switch in parallel thereto. The segment I53 of the rotary switch is positioned relative to the crank shaft I31 so that the rotary switch becomes closed an instant before the auxiliary switch I49 of the circuit breaker opens, and the segment is of sufiicient length so that it maintains the rotary switch closed and the motor circuit energized until the crank arm I39 has effected closing of the breaker and has been rotated to the position shown in Fig. 2 of .the drawings in which it is out of the way of the extension I43 of the operating lever 51.

A centrifugal brake mechanism I6I is disposed within the lower end of the motor housing I23 and this brake mechanism serves to bring the motor to a stop promptly after the motor circuit is deenergized by the opening of the rotary switch I5 I The brake mechanism IBI comprises a brake shoe carrying arm I63 secured on the lower end of the motor shaft, which carries a pair of brake shoes I65 at its opposite ends. The brake shoes I65 are pivotally mounted onthe ends of the arm I63 by pivot pins I61 and are arranged to be moved into engagement with an internal braking surface I69 in the motor casing by centrifugal force when the motor rotates.

The operation of the motor operating unit I2I is briefly as follows. When the circuit breaker is in open circuit position and it is desired .to close the circuit breaker, the motor energizing circuit I45 is energized by closing the manual control switch I41. Since the auxiliary switch I49 is in closed position when the breaker is open the motor is energized and rotates the crank arm in a clockwise direction as viewed in Fig. 2. During the rotation of the crank arm by the motor, the crank roller I4I engages the extension I43 of the operating lever 51 as shown in Fig. 4, and moves the operating lever upwardly toward closed position. The rotary switch I5l closes before the auxiliary switch I49 opens so that the motor remains energized and rotates the crank arm through a cycle to effect closing of the breaker. The rotary switch I5I opens the motor energizing circuit after the crank arm I39 has moved the operating lever to fully closed position, and the brake mechanism I6I brings the motor and crank arm to a stop in approximately the position shown in Fig. 2 in which the crank arm is in a position clear'of the operating lever extension I43.

It will be noted that the crank arm I 39 is disposed so that it makes an angle of substantially 90 with a line drawn from the point of contact of the roller I4I with the extension I43 of the operating lever, to the fixed pivot 55 of the operating lever at the time the circuit breaker reaches fully closed position as indicated by the dotted outline of the crank in Fig. 2. This arrangement provides a mechanical advantage which ininoreases as the circuit breaker approaches closed position and becomes a maximum. at the closed position of the breaker. The mechanical advantage is further increased by the action of the operating toggle BI63 which also provides an increasing mechanical advantage as the breaker approaches closed position and becomes a maximum at the closed position of the breaker. Due to the mechanical advantage provided by the operating toggle and the mechanical advantage provided by the arrangement of the crank arm I39 with respect to the operating lever 51, the load imposed upon the driving motor is substantially constant throughout the closing operation, despite the fact that the tension of the circuit opening spring increases during closing of the breaker and has the force of the contact pressure springs 49 added thereto as the breaker approaches closed position.

Since the circuit breaker mechanism automatically resets itself and the operating lever moves to open position upon tripping of the breaker, the motor operating unit is only called upon to close the circuit breaker, and hence does not have to perform any special resetting operation. The crank arm I39 always stops in a position out of the way of the extension I43 of the operating lever 5?, thus making it possible to close the circuit breaker manually by the lever 51 without interference by the motor unit and without disengaging any levers or clutch.

While the invention has been disclosed in ac- I cordance with the provisions of the patent statutes, it is to be understoodthat various changes in the structural details and arrangement of parts thereof might be made without departing from some of the essential features of the invention. It is desired, therefore, that the language of the appended claims be given the broadest reasonable interpretation permissible in the light of the prior art.

I claim as my invention:

1. A circuit breaker having relatively movable contacts, operating mechanism therefor comprising spring means for applying a force to open said contacts, an operating lever pivoted on a fixed support for closing said contacts, a rotatable crank arm disconnected from said lever for engaging and moving said lever to close said contacts, means comprising an electric motor for rotating said crank arm through a cycle to close said contacts and stop the crank arm in a position clear of said lever, said operating lever also being manually operable to close said contacts, means for holding said contacts in fully closed position independently of said operating lever against the force of said spring means, means movable from a normal position to a tripped po sition to cause opening of said contacts irrespective of the position of said operating lever, means for automatically resetting said movable means and said holding means following a tripping operation and a trip device operable to cause movement of said movable means to tripped position.

2. A circuit breaker having relatively movable contacts, operating mechanism therefor comprising spring means for applying a force to open said contacts, an operating lever pivoted on a fixed support and movable about its fixed pivot; from an open position to a closed position to close said contacts, a rotatable member disconnected from said lever for engaging and moving said lever to close said contacts, means comprising an electric motor for rotating said rotatable mem ber through a cycle to close said contacts and stop said rotatable member in a position clear of said operating lever, said operating lever also being manually operable to close said contacts, means for restraining said contacts in fully closed position independently of said operating lever against the force of said spring means, said restraining means including a member movable from a normal position to a tripped position to cause opening of said contacts irrespective of the position of said operating lever, said movable member being biased to tripped position at least i when said contacts are closed, holding means for normally maintaining said movable member in its normal position, a trip device operable to cause said holding means to permit movement of said movable member to tripped position, and resetting means for automatically resetting said movable member and holding means to normal position following tripping of the circuit breaker, said operating lever being biased to open position when the breaker is open.

3. A circuit breaker having relatively movable contacts, operatingmechanism therefor comprising spring means for applying a force to open said contacts, an operating lever having a fixed pivot about which it is movable from an open position to a closed position to effect closing of said contacts, a rotatable crank arm disconnected from the lever for engaging and moving said lever to close said contacts, means comprising an electric motor for rotating said crank arm through a cycle to close said contacts and stop said crank arm in a position clear of said operating lever, said operating lever also beingoperable manually to close said contacts, means for restraining said contacts in fully closed position independently of said operating lever against the force of said spring means, said restraining means including a member movable from a normal position to a tripped position to cause opening of said contacts irrespective of the position of said operating lever, said movable member being biased to tripped position when the contacts are closed, a linkage pivotally connected to said movable member for normally holding said member in its normal position, said linkage constituting the sole means for preventing movement of said movable member to tripped position, and a trip device operable to cause said linkage to permit movement of said movable member to tripped position, and means for automatically resetting said movable member and said linkage to normal position following tripping of the breaker.

4. A circuit breaker having relatively movable contacts, operating mechanism therefor comprising spring means for applying a force to open said contacts, an operating lever having a fixed pivot about which it is movable from an open position to a closed position to eifect closing of said contacts, a rotatable crank arm disconnected from the lever for engaging and moving said lever to close said contacts, means comprising an electric motor for rotating said crank arm through a cycle to close said contacts and stop said crank arm in a position clear of said operating lever,

said operating lever also being operable manually to close said contacts, means for restraining said contacts in fully closed position independently of said operating lever against the force of said spring means, said restraining means including a member movable from a normal position to a tripped position to cause opening of said contacts irrespective of the position of said operating lever, said movable member being biased to tripped position when the contacts are closed, a linkage pivotally connected to said movable member for normally holding said member in its normal position, said linkage constituting the sole means for preventing movement of said movable member to tripped position, a trip device operable to cause said linkage to permit movement of said movable member to tripped position, and means for automaticaily resetting said movable member and said linkage to normal position following tripping of the breaker, said operating lever being biased to open position when the contacts are open.

5. A circuit breaker having a movable switch member biased to open circuit position, operating mechanism therefor comprising an operating toggle connected to said switch member, means for normally holding one end of the operating toggle in fixed operative position, a pivoted operating lever movable about a fixed pivot from an open position to a closed position for moving the knee of said toggle to an overset position to thereby cause movement of the switch member to closed position, a trip device operable to cause said holding means to permit movement of said end of the toggle to a tripped position to thereby cause movement of the switch member to open circuit position irrespective of the position of said operating lever, said operating lever being biased to open position when said switch member is in open circuit; position, a rotatable crank arm for engaging and moving the operating lever to closed position to close the breaker, means including an electric motor operable to rotate said crank arm through a cycle to close the breaker and stop the crank arm in a, position clear of the operating lever, said operating lever also being manually operable to close the breaker.

6. A circuit breaker having a movable switch member biased to open circuit position, operating mechanism therefor comprising an operating toggle connected to said switch member, means for normally holding one end of the operating toggle in operative position, a pivoted operating lever movable about a fixed pivot from an open position to a closed position for actuating said 3 toggle to move the switch member to closed position, said toggle and holding means in the closed position of said breaker acting to hold said switch member is closed position independently of said operating lever, a trip device operable to cause said holding means to permit movement of said end of the toggle to a tripped position to thereby cause movement of the switch member to open circuit position irrespective of the position of said operating lever, said operating lever being biased to open position when said switch member is in open circuit position, spring means for automatically resetting said one end of the operating toggle and said holding means to normal operative position following tripping of the breaker, a rotatable crank arm for engaging and moving the operating lever to closed position to close the breaker, means including an electric motor operable to rotate said crank arm through a cycle to close the breaker and stop the crank arm in a position clear of the operating lever, said operating lever also being manually operable to close the breaker.

7. A circuit breaker having a movable switch member biased to open circuit position, operating mechanism therefor comprising an operating toggle connected to said switch member, a linkage pivotally connected to one end of said toggle and having a normal position in which it holds said end of the toggle in operative position, a pivoted operating lever movable about a fixed pivot from an open position to a closed position for actuating said toggle to move the switch member to closed circuit position, a trip device operable to cause said linkage to permit movement of said end of the toggle to a tripped position and thereby cause movement of the switch member to open circuit position irrespective of the position of said operating lever, said linkage constituting the sole means for preventing movement of said end of the toggle to tripped position, a rotatable crank arm for engaging and moving said operating lever to closed position, and an electric motor means operable to rotate said crank arm through a cycle to close the breaker.

8. A circuit breaker having a movable switch member biased to open circuit position, operating means therefor comprising an operating toggle pivotally connected to the switch member, a linkage pivotally connected to one end of said toggle and having a normal position in which it holds said end of the toggle in operative position, a pivoted operating lever movable about a fixed pivot from an open position to a closed position for actuating the toggle to move the switch member to closed circuit position, said toggle and said linkage in the closed position of the breaker acting to hold said switch member in closed position independently of the operating lever, a trip device operable to cause said linkage to permit movement of said end of the toggle to a tripped position to thereby cause movement of the switch member to open circuit position irrespective of the position of the operating lever, said operating lever being biased to open position when the switch member is in open circuit position, spring means for automatically resetting said one end of the toggle and said linkage to normal position following tripping of the breaker, a rotatable crank arm for engaging and moving said operating lever to closed position, means including an electric motor operable to rotate said crank arm through a cycle to close the breaker and stop said crank arm in a position clear of said operating lever.

9. A circuit breaker having a movable switch member, a spring for biasing said switch member to open circuit position, operating mechanism comprising an operating toggle pivotally connected to said switch member, a toggle linkage pivotally connected to one end of said operating toggle and having normal position in which it holds said end of the operating toggle in a normal fixed position, a pivoted operating lever movable about a fixed pivot from an open position to a closed position for actuating the operating toggle to an overset position to close said switch member, a trip device operable to cause collapse of said holding toggle linkage to permit movement of said one end of the operating toggle to tripped position and thereby cause movement of the switch member to open circuit position irrespective of the position of said operating lever, said operating lever being biased to open position when the switch member is in open circuit position, spring means for automatically resetting said one end of the operating toggle and said toggle linkage to normal position following tripping of the breaker, said toggle linkage constituting the sole means for preventing tripping movement of said one end of the operating toggle, a rotatable crank arm for engaging and moving the operating lever to closed position, and means including an electric motor operable to rotate said crank arm to close the breaker and stop the crank arm in a position clear of the operating lever, said operating lever also being movable to closed position by manual means to close the breaker.

10. A circuit breaker having a movable switch member biased to open circuit position, operating mechanism therefor comprising an operating toggle connected to said switch member, holding means having a normal position in which it holds one end of said operating toggle in a normal fixed position, a pivoted operating lever movable about a fixed pivot from an open position to a closed position for actuating said toggle to a slightly overset position to close the breaker, a trip device operable to cause said holding means to permit movement of said end of the operating toggle to a tripped position to thereby cause movement of the switch member to open circuit position irrespective of the position of the operating lever, said operating lever being biased to open position when the switch member is in open circuit position, spring means for automatically resetting said one end of the operating toggle and said holding means to normal position following tripping of the breaker, a rotatable crank arm for engaging and moving the operating lever to closed position, means including an electric motor operable to rotate said crank arm through a cycle to close the breaker and stop said crank arm in a position clear of said operating lever, said crank arm being at an angle of substantially degrees to a line drawn from the point of contact of the crank arm with the lever to the pivot axis of the lever at the time the switch member reaches closed circuit position.

11. A circuit breaker having a base, relatively movable contacts on said base, a U-shaped frame secured to said base with the sides of the frame perpendicular to the base, operating mechanism for said contacts mounted on said frame comprising an operating lever pivoted on a fixed pivot on the frame and movable from an open position to a closed position to efiect closing of said contacts, means for holding said contacts in closed position independently of said operating lever, means movable from a normal position to a tripped position to cause opening of said contacts irrespective of the position of said lever, a trip device operable to cause movement of said movable means to tripped position, means for automatically resetting said holding means and said movable means following tripping of the breaker, a motor unit removably secured to a side of said frame comprising a rotatable crank arm for engaging and moving the operating lever to closed position to close the contacts, an electric motor for rotating said crank arm through a cycle to effect closing of said contacts, and means for causing said crank arm to stop in a position clear of said lever after completing a closing operation, said operating lever also being operable manually to close said contacts.

JOHN W. MAY.