US2359139A - Circuit breaker - Google Patents

Description

Sept. 26, 1944. J w MAY AL 2,359,139

CIRCUIT BREAKER Filed Oct. 21, 1941 4 Sheets-Sheet l WITNESSES: INVENTORS Z4 John W May and TU Q Lindsfrom.

ATTORNEY Sept. 26, 1944. w, M EI-AL 2,359,139

CIRCUIT BREAKER Filed 001:. 21, 1941 4 Sheets-Sheet 2 Eimefal WITNESSES:

Tyre Lindsfrom ATTORN Sept. 26, 1944. J. w. MAY EIAL 2,359,139

CIRCUIT BREAKER Filed Oct. 21, 1941 4 Sheets-Sheet s J0]??? 14/ May and Tare Lina 51mm.

BY W A'TTokN Patented Sept. 26, 1944 2,359,139 cnwurr BREAKER John W. May, Pittsburgh, and Ture Lindstrom,

Edgewood. Pa., assignors to Westinghouse Electric 8: Manufacturing Company, East Pittsburgh, Pm, a corporation of Pennsylvania Application October 21, 1941, Serial No. 415,924

18 Claims.

This invention relates to circuit interrupters, and more particularly to circuit breakers of the type which are automatically operated in response to overload currents in the circuit controlled by the breaker.

One object of the invention is to provide a cir cult breaker with an improved device of simple and inexpensive construction, which is operable to cause the breaker to automatically open its contacts in response tooverloads in the circuits.

Another object of the invention is the provision of an improved circuit breaker which is capable of being tripped by the application of a relatively light tripping force by the electroresponsive trip means.

Another object of the invention is the provision of a circuit breaker having a novel trip device comprising a spring means in which energy is stored by the closing movement of the breaker and which is released by a latch to cause automatic opening of the breaker mechanism in response to predetermined overload conditions in the circuit.

Another object of the invention is the provision of a circuit breaker having a novel tripping means comprising a spring means connected between a tripping element and a part movable with the movable contact assembly, the tripping element being normally held in inoperative position by a latch which is adapted to be released in response to abnormal current conditions in the circuit.

Another object of the invention is the provision of a circuit breaker as previously described wherein the opening movement of the breaker acts through the tripping spring to reset the tripping element to latched position.

Another object of the invention is the provision of a circuit breaker as previously described wherein the spring means for tripping the breaker and for resetting the trip device also serves to permit overtravel of the parts to which the spring is connected in both directions of operation.

Another object of the invention is to provide a circuit breaker having an improved trip mechanism which is reset automatically when the contacts are opened.

Another object of the invention is to provide a circuit breaker wherein the movement of the operating mechanism to open the contacts resets the trip device.

Another object of the invention is to provide a circuit breaker with a novel spring device which is normally under tension to efiect tripping Still another object of the invention is to pro.-

vide a circuit breaker with a novel linkage operable in one direction to trip the breaker and operable in another direction to reset the trip device.

The novel features that are considered characteristic of the invention are set forth in particular 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 description of one embodiment thereof when read in conjunction with the accompanying drawings, in which:

Figure 1 is a vertical sectional view through the center pole of a three-pole circuit breaker embodying the features of the invention;

Fig. 2 is a horizontal sectional view on an enlarged scale taken substantially on line 11-11 of Fig. l, and showing the trip device of the breaker;

Fig. 3 is a fragmentary view showing the contact arm for the outer poles of the breaker;

Fig. 4 is an enlarged sectional view through the trip device for the center pole taken substantially on line IV--IV of Fig. 2, and showing the trip device just after the breaker has been tripped by the bimetal trip element, but before the contacts have opened;

Fig. 5 is an enlarged sectional view similar to Fig. 4, but showing the parts of the trip mechanism in the positions assumed after the breaker has been tripped by the bimetal trip element and after the contact arm has moved to open the contacts, but before the bimetal trip element has cooled;

Fig. 6 is an enlarged sectional view through the resilient linkage connecting the trip lever to the contact arm; and

Fig. '7 is a fragmentary view, partly in section, taken on line VII-VII of Fig. 4, showing the construction of a part of the trip device.

Referring particularly to Figs. 1 and 2 of the drawings, the circuit breaker, which is of the multi-pole type, is mounted on a base ll of molded insulating material. Secured to the base II is a frame structure comprising a pair of substantially parallel side franes I1 rigldlyconnected adjacent the base I! by a cross-frame I9, whereby the frame structure is secured to the central part of the base II through the agency of bolts 2| and 23. The side frames I1 are Joined at their outer ends by cross-members 25 and 29 to form a rigid framework. The breaker mechanism may be enclosed in'a-casing, indicated by dot and dash lines at I3, which may be suitably secured to the base II.

A contact arm 39 for the center pole of the breaker is provided with a pair of spaced arms 3| pivotally mounted on a rod 29 supported by the side frames I1 (see also Fig. 2). The arms 3| are rigidly connected by a cross-bar 32 adjacent the pivot 29. At its free end, the contact arm 39 for the center pole is provided with spaced projections 33, and a movable contact member 35 is pivotally mounted on a pivot pin 31 supported in the projections 33.

A movable contact 39 secured on the contact member 35 cooperates with a stationary contact 49 mounted on a conductor 4| secured to the base I I by bolts 43. The conductor 4| is bent at right angles and projects through the base II where it forms a terminal 45.

Contact pressure is provided by a spring 93 surrounding a. rod 5| pivotally connected to the contact member 35. The rod 6| slidably projects through an opening in a projection 59 on the contact arm 39, and the spring 63 is compressed between this projection and a washer 65 secured to the rod 6|.

The circuit breaker of the instant invention is of the multi-pole type, and each pole is provided with a stationary contact and a corresponding movable contact similar to the contacts of the center pole. However, only the center pole is provided with a contact arm 39 supported by pivoted arms 3|. A tie-bar 61 surrounded by a sheath 69 of insulating material is securely clamped in the arm 39 by means of a split clamp 19 and a bolt 1|. The tie-bar 61 extends across all of the poles of the breaker, and has brackets 13 (Fig. 3) clamped thereon by means of a clamp 11 and a bolt 18, there being a bracket 13 associated with each of the outer poles of the breaker. The insulating sheath 69 between the tie-bar and the clamps 19 aand 11 insulates the three movable contacts 35 from the tie-bar. Each of the brackets 13 for the outer poles is provided with spaced projections 33 which pivotally support a contact member 35. This contact member is the same as the contact member described in connection with the description of the contacts for the center pole, and like parts have been given the same reference characters. The contact members 35 for the outer poles are pivoted on pivot pins 31 and are provided with contact pressure springs 63. The stationary contact and terminal for each of the outer poles is identical to that of the center pole previously described.

Since the brackets 13 which carry the outer contact members 35 are mounted on the tie-bar 61, which is securely clamped in the contact arm 39 (Fig. 1) for the center pole, it is clear that operation of the contact arm 39 will simultaneously operate the contacts for all of the poles of the breaker.

When the contact arm 39 is rotated clockwise to open the contacts, the springs 53 cause the contact members 35 to rotate in a counter-clockwise direction about their pivot pins 31 so that only the tip portions of the movable contacts engage the stationary contact members 4| prior to separation of the contacts. Continued clockwise movement of the contact arm 39 causes nuts 15 on the rods II to strike the projections 59 and thus limit the movement of the contact members 35 relative to the contact arm 39, and the three movable contacts are then moved to open position with the contact arm 39.

The are incident to the rupture of the circuit is extinguished by an arc extinguisher 13, one being provided for each pole. Such arc extinguishers are well known in the art and comprise, generally, a stack of slotted plates disposed adjacent the path of movement of each contact member 35. The plates of the extinguisher draw the arc toward the ends of the slots,

which results in breaking up the arc into a plurality of short arcs and causes said arcs to be cooled and extinguished.

The electrical circuits for the several poles of the breaker are essentially the same, each circuit extending from the terminal 45 through the conductor 4|, contacts 49 and 39, the contact member 35, a flexible shunt conductor 19, a connector 21 of conducting material, a conducton 9|, a connector 49 to which one end of the conductor 8| is secured by a screw 5|, to a terminal conductor 53 secured to the base II by a pair of bolts 55, one of which serves to secure the connector 49 to the conductor 53. The conducting member 21 of the center pole is secured to the cross piece I9 of the frame by the bolt 23, and the conducting members 21 of the outer poles are bolted to the base II with a spacer between the base and each member to align the outer conducting membera '21 with the corresponding element 21 of the centerpole. The terminals 45 and 53 of each pole serve to connect the breaker in an electrical circuit.

The contact arm 39, together with the tie-bar 91, is biased in a clockwise direction toward open contact position by a pair of springs (only one being shown) having one end anchored on a fixed pivot 31 in the frames I1, and the other end connected to a projection 88 on the arm 39. In the closed position of the breaker, the contact arm 39 is releasably restrained in closed contact position (Fig. 1) by means of a linkage and toggle mechanism, including a lever 89 comprising a pair of levers rigidly connected by a crossmember 1 and pivotaliy supported on a pivot 9| mounted on the main frame I1. A main operating toggle comprising links 93 and 95 oneratively connects the lever 89 and the contact arm 39. The link 93 is pivoted on a pivot I9I in the lever 89, and the toggle links 93 and 35 are pivotally connected by a knee pin 91. The link 95 is pivoted on a pivot pin 99 supported between the arms 3| of the contact arm 39. The link 95 comprises a pair of links joined by a cross-bar I I5, which cooperates with an extension of the link 93 to limit upward movement of the main operating toggle.

A link I93 connects the lever 39 to one arm of a lever I95 pivoted on the fixed pivot 81. The other arm of the lever I95 is pivotally connected to one end of a toggle link I91 having its other end pivoted to a toggle link I 99 by a knee pin III. The toggle link I99 is pivoted on a fixed pivot I I3 supported in the frame I1. The link I91 comprises a pair of links rigidly connected by a yoke II9, which is provided'with a projection bent outwardly therefrom, to which projection is secured an extension Hi. The purpose of the extension I2| is to cooperate with manually operable means to trip the breaker, as will be described later. The link I03 and the lever I05 each comprises a pair of parallel members joined by a yoke substantially as illustrated. The

toggle link I09 comprises a pair of links rigidly connected at their ends adjacent the fixed pivot II3 by a cross-member I23 having formed proiections I24 and I21 thereon.

The linkage just described serves to releasably hold the contact arm and consequently the contacts in the closed position. In the closed position, the main operating toggle 9395 is over center above a line connecting the centers of the pins 39 and IN, the overcenter position of the toggle being limited by the end of the link 33 engaging the cross-member II5 on the link 95. With the toggle 93-95 in its overcenter position, the force exerted by the springs 85, acting through the contact arm 30 and the toggle 93-35, biases the lever 89 in a clockwise direction. The tripping toggle I01-I09 is biased over center to the left of a line drawn through the center of the fixed pivot H3 and the point of connection of the link I01 with the lever I05, by a spring I28 tensioned between the yoke H9 and the fixed pivot II3. The overcenter movement of the toggle I01-I09 i limited by the projection I24 striking an adjustable screw I22 in the cross-member 25 of the frame. The toggle I01I 03 in its overcenter position, acting through the lever I05 and link I03, prevents clockwise rotation of the lever 09 and consequently holds the contact arm 30 in its closed contact position.

The tripping toggle I01-I03 is adapted to be moved to collapsed position to cause opening of the contacts by a trip device indicated generally at I33 (Figs. 1, 4 and 5) acting through a trip rod I35 slidably mounted in a bracket I38 secured to the frame I1. The trip device, when actuated in response to an overload current, thrusts the rod I35 upwardly. During its upward movement, the rod I35 strikes the formed portion I21 of the cross-member I23 of the tripping toggle link I09, and rocks said link clockwise about its fixed pivot II3, causing collapse of the tripping toggle I'I-I09 and linkage 99- I03-I05.

Collapse of the tripping toggle I01-I09 permits the springs 85 to rock the contact arm 30 in a clockwise direction to open the contacts. The main operating toggle 93-35'does not immediately collapse, but moves as a unitary linkage to transmit the movement of the contact arm to the lever 89, rocking this lever clockwise, and through the link I03 rocks the lever I also in a clockwise direction to complete the collapse of the tripping toggle I01I 09.

The clockwise or opening movement of the contact arm 30 is arrested by the tie-bar 61 striking a portion I31 of the frame I1, and at this time due to the momentum of the toggle 33-35, including the comparatively heavy cross-bar II5, the main toggle 93-35 is caused to move over center in a direction to cause its collapse. By the time the knee pin 31 of the main toggle has passed below the center line 99-IOI, the weight of the linkage and parts causes the main togcenter position and in restoring the lever I05, link I03 and lever 89 to their normal position. The main toggle 93-95 remains in its collapsed condition until the contacts are reclosed.

In order to'manually close the contacts, a manually operable handle MI is provided. This handle is secured on the outer end of a short shaft I42 rotatably supported in a bracket I43 of insulating material. The bracket I43 is secured by screws I44 and I48, respectively, to the crossmembers 25 and 26 of the frame I1. The free end of a crank arm I50, secured to the shaft I42 adjacent the bracket I43, is bifurcated and pivotally carries a downwardly extending link I5I. The lower end of the link I5I is notched and engages an hourglass-shaped roller I53 rotatably mounted on a cross-bar I41 rigidly connecting the outer ends of a pair of levers I45 pivotally supported on the shaft or fixed pivot 9|. Near their innerends, the levers I45 are rigidly connected by a cross-bar I43. The levers I45 and the crossbars I41 and I49 form a closing lever pivoted at 9I, the levers I45 being spaced apart and disposed on the outside of the frame I1. Projections I52 on the cross-bar I49 have mounted therein a pivot I51, upon which is rotatably mounted a roller I55.

Rotation of the handle MI in a clockwise or closing direction, indicated by the arrow (Fig. 1), thrusts the link I5I downwardly and, due to the cooperation of the link with the roller I53, rocks the closing lever I45 in a clockwise direction. During this movement, the roller I55 engages the link 93 of the now collapsed toggle 93-95 and moves said toggle to its overcenter position. Since at this time the toggle I01--I09 is over center in its restraining position, the lever 83 is prevented from moving. Consequently, the force applied to straighten the toggle 9395 rotates the contact arm 30 in a counterclockwise direction to close the contacts and tension the springs 85. The clockwise movement of the closing lever I45 and the roller I55 is sufficient to carry the toggle 9395 over center above the line 33-IOI, so that the contacts are held in their closed position until the breaker is again tripped.

As soon as the contacts are closed and the toggle 9335 is moved to its overcenter position, the handle I4 may be released, whereupon a spring I53 tensioned between a projection on the frame I1 and the closing lever I45 rocks the closing lever counterclockwise, thrusting the link I5I upwardly and rotating the handle to its neutral position (Fig. 1). The counterclockwise rotation of the lever I 45 is limited by the cross-bar I49 striking a stop I48 in the bracket I38.

The contacts 33-40 may be closed (and the trip device I33 reset) automatically by means of an electric motor I25 mountedon a plate I26 (see Fig. 2) secured to the side of the frame I1. The motor I25 may be energized from any suitable source and in a manner well known in the art, and when so energized it is adapted, through suitable driving connections, to rotate a crank disc I29 which carries an anti-friction roller I30. An arm I3I secured to the side of the closing lever I45 is provided with a cam surface I32 nor- 138.011) disposed in the path of rotation of the roller When the crank disc I29 is rotated, upon energization of the motor I25, the anti-friction roller I30 engages the cam surface I32 and rotates the arm I3I, and consequently the closing lever I 45 clockwise, straightening the toggle 93-95, in the manner previously described, to close the contacts. As soon as the roller I30 passes out of engagement with the arm I3I, the spring I69 acts to restore the closing lever I46'to its normal, unoperated position (Fig. 1). The motor I26 is deenergized by a suitable limit switch (not shown).

The breaker may be tripped manually by rotating the handle Ill through a small angle in a counterclockwise direction from its neutral position. Rotation of the handle in tripping direction causes a projection I6I (Fig, 1) on the link Iil to engage the previously described extension III on the yoke II9 of the toggle link I01, and move the tripping toggle I01I09 over center in a direction to cause its.collapse. This permits the springs 86 to open the contacts, as was previously described. Reclosing the contacts is eil'ected in the previously described manner.

The trip device I33 is removably supported on the circuit breaker to provide for interchanging of trip devices having different tripping characteristics. The trip device is mounted on a framework includin a U-shaped bracket I63 (Figs. 1, 2, 4 and secured to the center pole connector 21 by means of the screw 28, which secures the conductor 8| thereto. The bracket I63 has a pair of upwardly bent side members I65 (see Fig. 2) and a portion I61 (Fig. 4) to the underside of which portion I61 is secured a plate I69 of insulating material. Mounted on the plate I69 is a frame "I also of molded insulating material. An angular flange I13 (Fig. 2) molded integral with the frame I1I is secured to the plate I69 by screws I15.

The trip device I33 comprises a thermally responsive bimetal element operable on overloads below a predetermined value, and an electromagnet operable on overloads above the predetermined value, there being one bimetal element and one electromagnet for each of the three poles of the breaker. The conductor 8I previously mentioned extends downwardly from the connector 21, and is bent at right angles and extends to the right (F18. 5) along the bottom face of the plate I69 for a predetermined distance where it is bent back upon itself. ductor strip is made of reduced width to provide an increased resistance portion so that it serves as a heater for the bimetal element. Just to the left of the plate I69, the conductor 8| is again bent toward the right and then downwardly to the connector 49,

The upper leg of the loop of the conductor BI is secured to the plate I69 by a rivet I11 (Figs. 4 and 5), and the reversely bent portion of the loop is secured to a bimetal element I19 and to a bracket I8I (see also Fig. '7). The downwardly extending leg of the conductor 8| passes between the legs of a U-shaped magnet core I83, which, together with the bracket I8I, is securely attached to projections I85 and I81 (Fig. 7)

of the frame I69 by means of rivets I89. A block I9I of insulating material is inserted between the legs of the loop of the conductor 8| to separate the legs and to form a substantially rigid structure.

Overload currents traversing the circuit of any pole of the breaker, and consequently the conductor 8I of any pole, serve to heat thebimetal I19 of the affected pole and to energize the corresponding magnet core I83.

A movable armature I93 is secured on the end of a rod I95 slidably mounted in an opening in a downwardly extending portion I91 of the bracket I8I. A spring I99 compressed between a shoulder on the rod I95 and the bracket This looped portion of the con- I 9| maintains the armature I93 in open air gap position (Figs. 1 and 4), and returns the armature to this position from its attracted position. The right-hand end (as viewed in Figs. 1, 4 and 5) of the rod I96 is provided with a head 2M which engages a U-shaped notch molded in a tripbar 203. The trip bar is of molded insulating material, and has a metal member 266 molded therein at each end. The members 266 (only one of which is shown) are pivotally supported on spaced brackets 201 secured to and depending from the plate I69, and serve to \pivotally support the trip bar. At their lower ends, the brackets 201 support a cover 209 of insulating material held in place by screws 2i I. The trip bar 203 is biased to its latching position (Fig. 1) by a spring 2I3 (Figs. 4 and 5) compressed between a projection 2I5 of the trip bar and the plate I69.

Only one trip device I33 has been described. However, it is to be understood that a plurality of trip devices are provided, one for each of at least two poles of the breaker, all of which are mounted on the plate I69 substantially as illustrated and described. Each of the trip devices is operable in response to overload conditions in the fcilcllit of their corresponding poles to rotate the trip bar 293 in tripping direction to trip the breaker, the trip bar extending across all of the poles of the breaker.

Attached to the trip bar 203 is a latch member 2I1 provided with a latch projection 2I9 and a limit projection 22I. The latch member 2I1 is adapted to engage the end of a latch arm 223 pivotally supported on a short shaft 226 mounted in the side members I of the U-shaped bracket I63. The latch arm 223 is provided with a yoke 221, one end of which forms an arm 223 (Fig. 2) bearing on the shaft 225. A spring 23I is coiled about the shaft 225 and disposed to bias the latch arm 223 in a counterclockwise direction (Fig. 1) toward its latched up position.

A pair of locating members 233 is rigidly supported on a rod 235, mounted in the frame I1, and on the shaft 29. Each of the members 233 is provided with a open slot embracing the shaft 225 to aid in locating the trip device I33 when it is installed in the breaker, and to assist in supporting the trip device after it is installed. The members 233 are spaced apart by a spacer 231 surrounding the rod 235 and a spacer 239.

The trip device I33 does not itself operate the trip rod I35 to trip the breaker, but releasably restrains a tripping mechanism, indicated generally at 240 (Fig. 5) in operative position. The tripping mechanism 240, when released upon operation of the trip device I33, operates the trip rod I35 to trip the breaker.

The trip mechanism 240 is mounted on a laterally extending bar 2 molded integral with the frame Hi. The bar I supports a bracket 243 comprising a pair of parallel side plates 246 rigidly connected by a yoke 241, which yoke is secured to the bar MI by bolts 249. The upper ends of the plates 245 between them support a pivot shaft 25I, upon which is pivotally mounted a lever comprising a pair of arms 253, one of which has a downwardly projecting extension 255 engageable with the yoke 221 of the latch arm 223. The arms 253 are rigidly joined by a yoke 259, and at their free ends carry a pivot pin 26I. A pair of links 263 pivoted on the pin 26I are pivotally connected to spaced arms 266 'of a bell crank or trip member 261 by means of a pivot pin 269. The bell crank 261 comprises the spaced arms 235 connected by a yoke 21!, the bell crank being pivotally supported on a pivot pin 212 mounted in the lower ends the spaced plates 235. The other arm 213 of the bell crank 23! is integral with one oi the arms 233 and has an ear 215 bent at right angles to its free end. An adjustable screw 21! is mounted in 'the ear 215, and is locked in position by a lock nut 219.

When the trip mechanism 240 is operated, as will be described later, the bell crank 23! is rocked counterclockwise, and the screw 21! strikes the lower end of the previously described tri rod I35 to effect tripping oi the breaker.

The point of connection 23! of the links 253 and 233 is connected to the arms 3! of the contact arm 30 by means of a resilient linkage indicated generally at 23! (Figs. 1, 4, and 6). Referring particularly to Fig. 6, the resilient linkage 23! comprises a cylinder 233, pivotally mounted on a rod 235 which extends through a transverse opening in the cylinder and through suitable openings in the arms 3! of the contact arm 33, a rod 23! pivotally supported on the pin 23!, and a compression spring 239 compressed between washers 29! and 293 in the cylinder. The washer 29! is adapted to engage the inner end of a cylindrical sleeve 295 mounted in the cylinder 233 and held in place by the rod 235 passing therethrough. The sleeve 295 acts as a 'limit stop to limit the expansion of the spring 239; the washer 293 engaging the inwardly flanged end 291 01 the cylinder 233 serves the same purpose. A spacer 299 (Fig. 4) surrounding the rod 285 spaces the linkage 23! adjacent one of the arms 3! and maintains it in alignment with the linkage 253233.

. In the normal untripped condition, the flexible linkage 23! is under tension, that is, the rod 23'I-is slightly drawn out of the cylinder 233, giving a greater compression to the spring 239 than obtains with the parts in the positions shown in Fig. 6. The force of the spring 239 is applied to the pin 26! and biases the lever 253 and the bell crank 23! in a counterclockwise or tripping direction. Movement of the lever 253 and bell crank 23! is normally prevented by engagement of the projection 255 with yoke 22'! of the latch arm 223, which is normally latched up by the latch member 2 I9 (see Fig. 1).

Upon the occurrence of a persistent overload current below a predetermined value in the circuit of any one of the poles of the breaker, the current flowing through the corresponding con ductor 3! heats the bimetal element I19 and causes it to flex in a downward direction. The free end of the bimetal engages an adjusting screw 33! held in place in the trip bar 233 by a lock nut 303 and rocks the trip bar clockwise to unlatch the latch am 223. As soon as this occurs, the linkage 23! contracts, due to the expansion of the spring 239 (Fig. 6) within the cylinder 233, rocking the lever 253 counterclockwise. This causes the toggle comprising the lever 253 and link 253 to move further above the center line 25I-239, and rocks the bell crank lever 23! counterclockwise to trip the breaker through the agency of the trip rod I35.

The parts just described are shown in Fig.4 in this position, that is, an instant after the breaker is tripped, but before the contacts have opened.

Operation of the trip rod, as previously described, causes collapse of the linkage 93, 95, 39, I33, I35, I3! and I09 (Fig. 1) which permits the spring 35 to rotate the contact arm 33 to open the contacts. As the contact arm 33 rotates clockwise in opening direction, the action of the linkage 23! (Fig. 5) is reversed, and the cylinder 233 moves with the contact arm 33,, and, acting through the washer 29!, the spring 239 and the washer 293, which at this time is in engagement with a shoulder on the rod 231, thrusts the rod 23'! in a direction to straighten the toggle 253-433. This simultaneously accomplishes two things. Acting through the link 233, the bell crank lever or trip member 23'! is rocked clockwise to its normal position to permit restoration of the trip rod to its normal position, which permits resetting of the linkage 39, I33, I35, I31 and I39 (Fig. 1). The straightening of the toggle 253233 also rocks the lever 253 clockwise,

whereupon the spring 23! rotates the latch arm 223 counterclockwise slightly beyond latching position, this movement of the arm 223 being limited by a projection 305 on the bracket I33.

As the bimetal I19 cools and resumes its normal shape (Fig. 1), the spring 2I3 rotates the trip bar 203 counterclockwise to latching position with the projecting latch 2! 9 in the path of clockwise movement or the latch arm 223. The

' counterclockwise movement of the trip bar 233 is limited by the projection 22! thereon strikin the arcuate end of the latch arm 223.

Now when the contact arm 33 is rotated in a counterclockwise or closing direction, upon proper operation of the handle Ill, or energization of the motor I25, to close the contacts, the linkage 23! moves therewith, rocking the lever 253 counterclockwise a slight amount and through the projection 255 rocks the latch arm 223 clockwise a slight amount until it is arrested by engagement with the latch2! 9 thus restraining the latch arm and the toggle 253233 in latched position. This also arrests the counterclockwise movement of the lever 253. Continued closing movement or the contact arm 33 again places the linkage 23! in tension, i.e., stores energy in the spring 239, in readiness for a succeeding tripping operation.

The circuit breaker is tripped instantaneously on overloads in the circuit through any of the poles exceeding a predetermined value; for instance, exceeding approximately ten times normal rated current. Upon the occurrence of an overload above the predetermined value, or a short circuit, the current flowing through the corresponding conductor 3! energizes the magnet core I33, which immediately attracts the armature I93. The armature draws the rod I toward the left (Fig. 5), the head 23! of said rod acting to rock the trip bar 233 in unlatching direction. When the trip bar 233 has unlatched the latch arm 223, the parts function to trip the breaker in the previously described manner. As soon as the contacts are opened and the circuit ruptured, the spring I99 returns the armature I93 and rod I95 to unattracted position, and the spring 2I3 rocks the trip bar 233 to latching position. The trip mechanism is rest upon movement of the contact arm 33 to open position, and the contacts reclosed as previously described.

The breaker is trip-free under all conditions. Should the handle Ill be held in its closed position against an overload current, holding the roller I55 against the toggle link 93, the contacts will open, since collapse of the linkage 39, I03, I35 and !3'I-I39 permits the toggle 93-95 to move in opening direction as a unitary linkage. When the clockwise movement of the contact arm 30 is arrested by the frame II, the force of the spring 85 is no longer applied to the toggle 93-95, and the linkage, consequently when the handle Ill is released and the closing lever H rotated to normal position, the weight of the linkage acts to move the toggle 93-45 over center-to collapsed position and reset the linkage 89, I03, I05 and NIL-I09. The contacts may now be closed in the previously described manner.

From the foregoing description it will be seen that the parts are so arranged that a very light load is applied to the latch member and therefore requires the application of a relatively light force by the current responsive trip device to unlatch the trip mechanism, the actual work 01' tripping the breaker mechanism being performed by the spring link. A further advantage resides in the provision of the resilient connection or linkage which operates in one direction to trip the breaker and is operable in another direction, upon opening of the contacts, to automatically restore the latch member to latching position without the necessity of preliminary manipulation of the closing mechanism. The resilient connection also permits operation of the mechanism without strain or breakage since it permits overtravel oi the parts in both directions.

Having described the preferred embodiment of the invention in accordance with the patent statutes, it is to be understood that various changes and modifications 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, operating mechanism for said contacts including closing means for closing said contacts, means operatively relating said closing means and said movable contacts, a trip mechanism including a toggle independent of said relating means, said toggle being biased in a direction to cause opening of the contacts, latch means for releasably restraining the trip mechanism, and a current-responsive trip device operable in response to overload circuit conditions to cause said latch to release the toggle and permit operation of the trip mechanism, said toggle being operable by the operating mechanism when the contacts are opened to permit relatching of the latch means.

2. In a circuit breaker, relatively movable contacts, operating mechanism for said contacts, a normally latched trip mechanism having a linkage including a compression spring biased to cause opening of the contacts, a current-responsive trip device operable to unlatch the trip mechanism, said operating mechanism acting through said linkage to reset the trip mechanism when said operating mechanism moves to open the. contacts.

3. In a circuit breaker. relatively movable contacts, operating mechanism operable to open and close the contacts, a releasable trip member operable to cause opening of the contacts, a linkage including a compression spring biasing said trip member in tripping direction, and a current-responsive trip device operable in'response to overload circuits to release the trip member, said operating mechanism acting through said linkage upon opening oi the contacts to cause resetting 01 parts of said current-responsive trip device.

trip mechanism including a toggle operable to enfect opening of the contacts. a spring means biasing said toggle in tripping direction at least when said contacts are closed, and a current-responsive trip device operable to cause operation or said toggle upon the occurrence of an overload, said spring means being operable by the operating mechanism upon opening 01' the contacts to reset the toggle and to permit-resetting 01 parts or said trip device.

5. In a circuit breaker, relatively movable contacts, a switch member movable to open and to close said contacts, actuating mechanism for moving said switch member to open and to closed circuit positions, a trip mechanism including a linkage biased to cause an opening operation 0! the contacts, a latch for latching the trip mechanism in operative position, and a current-responsive trip device operable to unlatch the trip mechanism upon the occurrence oi an overload, said switch member acting through said linkage when said member is moved to open the contacts to effect resetting of the trip mechanism.

6. In a circuit breaker, relatively movable contacts, actuating mechanism for said contacts, a contact arm operable to open the contacts, a trip member operable to cause said mechanism to open said contacts, a linkage including a spring for operating the trip member, means for releasably restraining said linkage and a current-responsive trip device for releasing the linkage upon the occurrence of an overload current, said spring being operable by the contact arm upon opening of th contacts to efl'ect resetting of the linkage.

7. In a circuit breaker, relatively movable contacts, operating mechanism for said contacts, a contact arm operable to open the contacts, a trip member, a toggle operatively connected to said trip' member, a resilient linkage connecting the toggle to the contact arm, said resilient linkage biasing the toggle in a direction to operate the trip member at least when said contacts are closed, a current-responsive trip device operable in response to predetermined circuit conditions to cause operation of the trip member, said resilient linkage being operable by the contact arm when said arm is operated to open the contacts to reset the trip member and permit resetting oi the trip device.

8. In a circuit breaker, relatively movable contacts, operating mechanism for said contacts, a contact arm operable to open the contacts, a trip member operable to cause opening of the contacts, a toggle operatively connected to said trip member, a resilient linkage connecting the toggle to the contact arm, said linkage biasing the trip member in tripping direction at least when said contacts are closed, and a trip device responsive to overload circuit conditions to cause operation of the resilient linkage, said linkage being operable by the contact arm upon opening of the contacts to reset the toggle and trip member.

9. In a circuit breaker, relatively movable contacts, operating mechanism for said contacts, a

trip member operable to cause opening of the contacts, a releasable linkage biasing the trip member in tripping direction at least when said contacts are closed, means for releasably restraining said linkage, and an electroresponsive trip device responsive to overload current to release said linkage, said linkage being operable by the operating mechanism upon opening of the contacts to reset the trip member and permit resetting or the'electroresponsive trip device.

10. In a circuit breaker, relatively movable contacts, operating mechanism for said contacts, a trip member operable to cause said mechanism to open th contacts, a linkage comprising a member connected to the operating mechanism, a reciprocable member cooperating with said member and connected to said trip member, and resilient means between the member and said reciprocable member, said linkage being operable to cause operation or the trip member, currentresponsive trip means responsive to overload currents to cause said linkage to operate the trip member, said linkage being operable by the operating mechanism when the contacts are opened to reset the trip member.

11. In a circuit breaker, relatively movable contacts, a switch member movable to open and to close said contacts, operating mechanism for said contacts, a trip member operable to cause opening of the contacts, a toggle operatively connected to the trip member, a linkage including a pair or cooperating members one of which is connected to the switch member the other being connected to the toggle, and aspring cooperating with said linkage, said spring biasing the trip' member in tripping direction at least when said contacts are closed, a latch normally restraining the toggle to thereby restrain said trip member,

and a current-responsive trip device operable in response to predetermined circuit conditions to cause said latch to release the toggle.

12. In a circuit breaker, relatively movable contacts, operating mechanism for said contacts including closing means for said contacts, means operatively relating said closing means to said movable contacts, releasable trip mechanism including a toggle independent of said relating means and operable to cause opening of the con-,

tacts, a resilient linkage biasing said toggle in tripping direction, a latch for releasably restraining said toggle, and a current-responsive trip device operable in response to predetermined circuit conditions to release the trip mechanism, said toggle being reset to operative position by opening of the contacts.

13. In a circuit breaker, relatively movable contacts, operating mechanism for said contacts,

a trip mechanism including a toggle movable to cause opening of the contacts, latch means to releasably restrain the toggle, means connecting the toggle to a part movable with the operating mechanism, said connecting means including a spring operable when the toggle is released to move the toggle to thereby cause opening of the contacts, a current-responsive trip device operable to cause release of the toggle, said connecting means being operable by the operating mechanism when the contacts are opened to restore the toggle to latching position.

14. In a circuit breaker, the combination of relatively movable contacts, operating mechanism for said contacts, a pivoted trip member operable to cause opening of the contacts, a linkage comprising a pair oi cooperating members one of said members being operatively related to the trip member. and the other member being connected to the operating mechanism, and a spring associated with said cooperating members to bias the trip member in tripping direction at least when the contacts are closed, said. spring acting when released to operate the trip member, latch means to releasably restrain the linkage, and a current-responsive trip device to operate the latch and'release the spring, said linkage being operable by. the operating mechanism acting through the spring to reset the trip member.

15. In a circuit breaker, the combination of relatively movable contacts, operating mecha. nism for said contacts, a contact member operable to open-the contacts, a trip member operable to cause opening of the contacts, a toggle operatively connected to the trip member, said toggle being biased in tripping direction, means for operatively connecting the toggle and the contact member, said connecting means comprising a member connected to the contact member, a member connected to the toggle, and a spring associated with said members, latch means for releasably restraining the toggle, and a currentresponsive trip device operable in response to overload circuit condition to release the toggle, said connecting means acting to transmit the movement of the contact members when the contacts are opened to reset the toggle.

16. A circuit breaker comprising relatively movable contacts, operating mechanism for said contacts, means comprising a resilient linkage including a compression spring connected to a part movable with the movable contact, said spring being compressed when said contacts are closed and being operable to cause an operation of the operating mechanism to open said contacts, means for releasably holding said spring in compressed condition, and current responsive means operable in response to predetermined overload conditions in the circuit for causing said holding means to permit operation of said linkage, the movement of said contacts to open position acting through said linkage to reset said holding means to holding position.

17. A circuit break r comprising relatively movable contacts, a member movable in accordance with the movement of said contacts, operating mechanism for said contacts, tripping means including a toggle, a spring connecting said member to said toggle and stressed when said contacts are closed, said toggle being operable to cause said operating mechanism to open said contacts, means for holding said spring in stressed condition, and a trip device operable in response to overload currents in the circuit to cause said holding means to permit the spring to operate said toggle, said movable member acting when the contacts open to reset the toggle.

18. A circuit breaker comprising relatively movable contacts, operating mechanism for said contacts, a switch member operable to open th contacts, a trip member operable to cause opening of the contacts, a resilient linkage connecting the switch member to said trip member, said resilient linkage biasing the trip member in tripping direction at least when the contacts are closed and acting when released to operate the trip member, latch means for releasably restraining the trip member, and a current-responsive trip device operable in response to overload circuit conditions to release the trip member, said resilient linkage being moved by the opening movement of said switch member to reset the trip member.

JOHN W. MAY.

TURE LINDSTROM.

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