US2383403A - Circuit breaker - Google Patents

Description

Aug. 21, 1945.

J. W. MAY ETAL.

CIRCUIT BREAKER Filed Dec. 17, 1941 o 2 Sheets-Sheet l ATTO EY Allg. 21, 1945. J, wI MAY ETAL 2,383,403

CIRCUIT BREAKER Filed Deo. 17', 1941 2 Sheets-Sheet 2 WlTNEssEs;

Patented Aug. A21, 1945 l CIRCUIT BREAKER John W. May, Pittsburgh, William il. Stuelleln, East McKeesport, and Meri E. Horn, Forest Hills, Pa., asslgnors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application December 17, 1941, Serial No. 423,360

(Ci. o-89) 8 Claims.

This invention relates to circuit breakers, and more particularly to trip-free circuit breakers wherein the contacts are trip free of the closing means.

Under certain circumstances, it is desirable to positively hold a circuit breaker in closed circuit condition against any force acting to cause opening of the breaker whether such force is due to an overload on the circuit controlled by the breaker, or due to shocks or jars.

It is an object of this invention to provide an improved circuit breaker in which the movable contacts are trip free of the closing mechanism and which is provided with manually operated means to prevent opening of the contacts.

Another object of the invention is to provide a lAnother object of the invention is to provide a circuit breaker with an improved locking device which is operable to render thetripping means ineffective to trip the breaker and which prevents operation of the operating mechanism to open the contacts.

Another object of the invention is to provide an improved circuit breaker wherein a toggle is operated to effect tripping of the breaker with a manually operable interposer to prevent tripping operation of the toggle.

Another object of the invention is to provide an improved circuit breaker in which the operating mechanism comprises a linkage including a plurality of toggles with manually operable means for preventing opening operations of the linkage.

Another object of the invention is to provide an improved circuit breaker in which a linkage is collapsiblel to cause opening of the contacts of the breaker with a single manipulative means engageable with different parts of said linkage to lock the breaker 'n closed circuit position.

The novel features that are considered characteristic of the invention are set forth in Darti'cular in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof will be best understood from the following detailed description of several embodiments thereof when read in connection 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 fragmentary plan view of a part of the circuit breaker showing the manual locking device,

Fig. 3 is a side elevational view of the circuit breaker illustrating a modified form of the locking device,

Fig. 4 is a fragmentary detail view showing the operating knob and the indicating device of the modified form of the invention, and

Fig. 5 is a fragmentary sectional view taken on line V-V of Fig. 3 and showing the pull rod locking device.

Referring to Fig. 1 of the drawings, the circuit breaker ls provided swith a common operating mechanism which is mounted in a U-shaped main frame I8 having parallel sides il joined by a cross member I9. The frame I6 is secured to the center portion of an insulating base il by means of bolts 2| and 23, and the outer ends of the sides of the frame are rigidly connected by a cross member 25.

The bolt 2l extends through the cross member I9 and serves to rigidly secure a connector 21 of conducting material to the cross member and to the base i i. A shaft 2l extends through an opening in the connector 21 and through openings in the sides of the frame It and pivotally supports a pair of arms Il having their outer ends integral with a contact arm lil for the center pole. The contact arms for the outer poles are not shown in the drawings buteach comprises a structure similar to the contact arm I0 for the center pole without the arms Il. The contact arms for the outer poles are rigidly secured to a tie bar 6l which extends across all three poles and which is clamped to the contact arm I0 for the center pole by a clamp 1I and a screw 1i, each of the contact arms being insulated from the tie bar 81 by means of sheaths of insulating material 69 between the tie bar 61 and the contact arms 30 for the several poles.

The contact structure for the several poles of the breaker are alike for which reason only the structure for the center pole will be described. The contact arm l0 pivotally carries a main contact member 4l and an arcing contact member II. The main contact member l1 is pivoted on a pivot 4. in Projections 5I of the arm Il, and the arcing 2 asaasos contact member 55 is pivoted on a pivot pin 51 in projection 59 oi' the arm 30.

The contact member 41 carries a contact 33, and a contact 35 is secured to the arcing contact member 55. These contacts 33 and 35 are adapted to engage respectively fixed contacts 39 and 31 secured on a conductor 4|. The conductor 4I which is secured to the base I I by bolts 43 extends upwardly and a bent portion thereof extends through an opening in the base I I, forming a terminal connector 45.

A spring 53 compressed between spring seats on the contact arm and on the contact member 41 provides contact pressure for the main contacts 33-39. Contact pressure for the arcing contacts -31 is provided by a spring 63 surrounding a rod 6| pivotally connected to the contact member 55. The spring 63 is compressed between a collar 65 seated on a shoulder on the rod 6| and the bottom of a recess formed in the contact arm 30. The rod 9| slidably projects through an opening in the recessed portion of the arm 30 and has a nut 15 on the end thereof, the nut 15 acting to limit counterclockwise rotation of the contact member 55 about its pivot 51 when the. arm 30 is moved to open the contacts. Counterclockwise movement of the main contact member 41 is limited by a shoulder 13 therein striking the body of the arm 30. The adjustment of the nut 15 on the rod 6| is such that the main contacts 33-39 open before the arcing contacts 35-31 open.

When the arm 30 is operated to open the contacts the arc resulting from the rupture of the current is extinguished by an arc extinguisher indicated generally at 16, there being one arc extinguisher for each pole of the breaker. While any suitable extinguisher may be employed, the one illustrated is of the spaced plate type and comprises, generally, a stack of slotted plates (not shown) disposed adjacent the path of travel of the arcing contact 35. The plates serve to draw the arc toward the ends of the slots where it is broken up into a plurality of short arcs which are quickly cooled and extinguished.

The arcing contact member 55 is connected by a flexible shunt conductor 11 to the main contact member 41 and this member is connected by means of a flexible shunt conductor 19 to the connector 21. Secured to the connector 21 by means of bolts 14 is a downwardly extending conductor 0| which is bent at right angles and extends between the legs of a U-shaped tripping magnet core IBI and through an opening in the base II. The end 83 of the conductor 9| forms a terminal connector which, together with the terminal connector serves to connect the breaker in an electrical circuit.

The electrical circuits for the several poles of the breaker are essentially the same; therefore, only the circuit for the center pole will be de scribed. This circuit extends from the terminal connector 45\through the conductor 4|, the main contacts 33-39, the main contact member 41, the flexible shunt conductor 19, the connector 21, the conductor 8| to the terminal connector 83. The circuit for the arcing contacts extends from the conductor 4| through the arcing contacts 31-35, the arcing contact member 55, the flexible shunt conductor 11, the main contact member I1 and over the previously described circuitl to the terminal connector 83.

The contact arm 30 for the center pole is biased in a clockwise (Fig, 1) or opening direction by a pair of springs 85. These springs are tensioned between a fixed pivot 91, on the frame I5, and

the contact arm 30. However, under normal circuit conditions, the contact arm 30 is releasably restrained in its closed contact position by means of a toggle and linkage which is collapsible to eifect opening of the contacts.

This collapsible linkage includes a lever 39 pivotally mounted on a fixed pivot 9| supported on the main frame I9, the lever 99 comprising a pair of levers rigidly connected by a cross member I I1. The lever 99 is operatively connected to the arms 3| of the center pole contact arm 30 by a main operating toggle comprising a toggle link 93 having one end pivoted on a pin |0| on the lever 99- and a toggle link 95 having one end pivoted on a pin 99 supported on the arms 3|. 'I'he link 95 comprises a pair of links rigidly joined by a cross bar ||5 and is pivotally connected to the link 93 by means of a knee pin 91.

The free end of the lever I9 is connected by'a link |03 to one arm oi' a lever |05 pivoted on the fixed pivot 91. The other arm of the lever |05 is pivotally connected to a toggle link |01 of a tripping toggle comprising the link |01 and a toggle link 09 pivoted on a fixed pivot |I3 in the frame I1, the toggle links |01 and |09 being pivotally connected by a knee pin I The toggle link 01 comprises a pair of links connected by a yoke I I9 having a bent portion to which is secured an extension |2I, the purpose of which is to cooperate with a manual handle |4| to trip the breaker, as will be more fully brought out later. The toggle link |09 comprises a pair oi' links joined by a yoke |23 having formed portions |25 and |21 thereon. 'I'he lever |05 comprises a pair of levers rigidly connected by a yoke |05, and the link |03 comprises a pair of links joined by a yoke |04.

The linkage just described, under normal conditions serves to releasably hold the contact assemblage including the movable contacts for all of the poles in closed contact position. In this position the main operating toggle 93-95 is over center above aline through the center of the pins 99 and |0I. A second toggle, one link of which comprises the overcenter links 93 and 95, and the other link of which comprises the lever 39, is over center above a line through the centers of the pins 99 and 9|. The overcenter movement of the main operating toggle 93-95 is limited by the projecting end of the link 93 engaging the cross bar Ill of the toggle link 95.

With the main operating toggle 93--95 and the toggle comprising linksl 93-95 and lever 39 in their overcenter position, as shown in the drawings, the springs 05 and the three sets of contact pressure springs 53 and 53 bias the lever 99 in a clockwise direction. Movement of the lever 99, however, is normally prevented by the tripping toggle |01- |09 which is biased over center in the left of a line drawn through the center of the fixed pivot ||3 and the point of connection of the toggle link |01 with `the lever |05, by means of a spring |29 tensioned between the yoke U9 and the fixed pivot ||3. The overcenter position of the tripping toggle |01-|09 is adjustably determined by the formed portion |25 of the yoke |23 engaging an adjusting screw |29 in the cross member 25 of the frame I5. The tripping toggle |01| 09 in its overcenter position, acting through the lever |05 and link |03, prevents clockwise rotation of the lever 89, and consequently holds the contact assemblage in the closed contact position against the biasing influence of the springs I5 and the springs 53 and 93.

The tripping toggle |01- |09 is adapted to be 9,838,403 3 the toggle 33-95 rotates the contact arm 30 counmoved over center outwardly in a direction toward collapsed position to cause opening oi' the contacts by means of a trip device indicated generally at |33. The trip device, when operated in response to an overload current, actuates a trip rod |35 which is slidable vertically through a shunt trip coil (not shown) enclosed in a casing |33 secured to the main frame I5. The shunt coil is adapted to be energized from a suitable source either automatically, or by a manual control switch, in a manner well known in the art to operate the trip rod |35 from a remote point. When operated either by the shunt coil or by the trip device |33, the trip rod |35 is thrust upwardly and strikes the formed portion |21 of the yoke |23 of the link |09and rocks said toggle link clockwise about the fixed pivot ||3. This movement causes collapse of the tripping toggle I31|09 permitting the springs 35 to rock the contact assemblage clockwise to open the circuit.

The main operating toggle 93-95 does not immediately collapse, but the force of the springs 35 applied through the main operating -toggle causes collapse of the toggle comprising links 33--95 and the lever 39 `rocking the lever 39 clockwise as viewed in Fig. 1. This movement is transmitted through the link |03 and lever |05 to complete the collapse of the tripping toggle |01-|09.

The clockwise or opening movement of the contact arm 30 is arrested by projections (not shown) thereon striking a portion |31 of the frame i3. At this time the rebound of the inertia of the main operating toggle 93-95 starts said toggle over center in a direction to cause its collapse. By the timethe knee pin 91 of the main toggle passes over center below the line 99|0| the weight of the parts causes the main toggle l93--95 to collapse and causes the lever 39,v

link |03, lever and the tripping toggle |01--I09 to be automatically reset to their normal positions. IThe main operating toggle 93-95 remains in its collapsed position until the breaker is closed.

The contacts are closed manually by operation of the previously mentioned handle |4|. The handle is secured to the outer end of a short shaft |42 rotatably mounted in a bracket |43 of insulating material which is secured to the outer end of the frame I6. A crank arm |44 secured on the shaft |42 has a depending link |5| pivotally connected to its free end. The lower end of the link |5| is notched and engages an hour glass-shaped roller |53 rotatably mounted on a cross member |41 rigidly connecting the outer ends of a pair of levers forming' a contact closing lever |45. The levers |45 are disposed one adjacent to each side of the frame I5 and are pivotally supported on the fixed pivot 9| the ends of which project beyond the sides of the frame I6 (see Fig. 2). The inner ends of the levers |45 are rigidly connected by a cross bar |49 from v-hich extend spaced projections |52. A roller |55 is rotatably mounted on a pin |51 supported in the projections |52.

The contacts are closed manually by clcckw'se rotation of the handle |4| which thrusts the link |5I downwardly and rotates the contact closing lever |45 in a clockwise direction. During this movement of the lever |45 the roller |55 engages the link 93 of the now collapsed operating toggle 93-95 and moves this toggle to its lextended overcenter position. Since at this time the tripping toggle HiT-|09v is over center in its restraining position, rotation of the lever 89v is prevented. and consequently the force applied to straighten v tion with the lever |05.

terclockwise to close the contacts and to tension the springs 35. The clockwisemovement of the closing levers |45 moves the toggle 93-35 over center above the line 99|0| so`that the contacts are held in the closed position until the breaker is again tripped.

Ay spring |59 having one end anchored to the lever |45 and the other end secured to the frame I5 is provided to restore the lever |45 and the handle |4| to their normal positions upon release of the handle following a contact closing operation.

The Contact closing lever |454 may be operated to close the contacts automatically by means of an electric motor |39. The motor is securely mounted on a plate suitably attached to one side of themain frame I6, and may be energized from any suitable source. When energized the motor is adapted to rotate a crank disc |30 which carries an anti-friction roller |3|. During this rotation the roller |3| engages a cam i'ace |32 of an arm |34 secured to the side of the closing lever and rotates said arm and the lever |45 clockwise to effect closing of the contacts in the manner previously set forth. As soon as the roller |3| passes out of engagement with the arm |34 the spring |59 acts to restore the closing lever |45 to its normal position. The motor |39 is deenergized by a suitable limit switch not shown) The circuit breaker may be tripped manually by rotating the handle |4| through a small angle in a counter-clockwise direction from its neutral position. When the handle is rotated counterclockwise it raises the link |5I. During this movement a projection on the link engages the previously described extension |2| on the yoke l0 of the toggle link |91, and rocks the link counterclockwise aibout its point of connec- This moves the tripping toggle |01|09 over center in the direction to cause its collapse and elect opening of the contacts in the manner previously described.

It was stated previously that the trip rod 35 is operated to effect tripping of the breaker by means of a trip device |33. There is a trip device |33 provided for at least two of the poles of the breaker but since they are alike only the trip device for the center pole will be described. This trip device includes the magnet core |6| and a frame comprising substantially parallel side members |63 rigidly connected by a yoke |65. The members |03 are provided with mounting feet |51 and bolts |69 extend through openings in the base I, the magnet core |3| and the feet |51 to rigidly secure the members to the base. A trip lever |13 is pivotally mounted on a rod |15 extending between and supported in the frames |33. The trip lever comprises a pair of spaced levers |13 having an armature |19 secured to one end, and connected by a yoke |11 at the other end. The -trip lever is biased against operation by the magnet by a spring |9| having one end booked onto the yoke |11 and the other end hooked'onto a vertically movable plate |93. An adjusting screw |95, provided with a knurled head |91 bearing against a formed projection |99 of the yoke |55, passes through an opening in the plate |93 and is provided with screw threads for moving the plate vertically to adjust the tension of the spring |9|. Spaced projection 20| on the yoke serves to support a scale plate 203 which bears suitableA indicia indicating the adjustment of the spring |9| as the tripping point of the breaker. An adjustable stop screw 205 in the yoke |55 is provided with a lock nut 201 and determines the open air gap of the magnet.

Rotatably mounted in a bracket |89, secured to the casing |38 housing the shunt trip coil, is a trip bar |81 extending across all of the poles of the breaker. A plurality of arms |85, one for each trip device is secured to the trip bar |81, the center one of the arms being disposed in alignment with the trip rod |35. An adjustable screw |8| is mounted in each of the yokes |11 in alignment with the arm |85 for its pole.

Normal rated current flowing through the circuit of the breaker causes slight energization of the magnet |6|. This energy, however, is insufficient to overcome the tension of the spring |9I. Upon the occurrence of an overload current above a predetermined value the flow of current through the conductor 8| energizes the magnet sufilciently to cause it to attract the armature |19 and operate the trip lever |13. Operation of the trip lever causes the screw to rock the arm |85 and the trip bar |81 clockwise which, as previously described, thrusts the trip rod |35 upwardly to effect tripping of the breaker.

It was stated previously that under certain circumstances it is desired to hold the contacts of the breaker inclosed position against any force acting to cause opening of the contacts. This is effected by manually locking the toggle and linkage mechanism in a manner to prevent collapse thereof. This not only prevents operation of the tripping toggle |01|09 but positively restrains the contacts in closed position.

This locking mechanism includes a cam member 209 secured to a shaft 2| I rotatably supported in spaced brackets 2|3 which are suitably secured to and supported by the sides of the frame I0. Also secured to the shaft 2I| is an arm 2|5 having its free end formed back on the body of the arm as at 2|1. A pivot pin 2I9 is supported in the ami 2|5 and the formed end 2 |1 thereof and a linkage 220 including a short rod 22| disposed in the U-shaped end of the arm is pivotally connected to the pin 2|9. The short rod 22| is threaded and thereby adjustably secured in the end of a larger rod 223 having an axially disposed opening in its other end. One end of a rod 225 is inserted in the opening and secured to the rod 223 by means of a pin 221, the other end of the rod 225 extending through a guide opening in an insulating plate 22S-secured to the bracket |43. A spring 23| compressed between the end of the rod 223 and the plate 229, biases the rod assemblage toward the left which movement is limited by an operating knob 233 secured to the outer end of the rod 225 and resting against the outer face of the plate 229.

The locking device is operated by manually grasping the knob 233 and drawing the linkage 220 outwardly. This rocks the arm 25|, the shaft 2li and the cam member 209 in a clockwise direction as viewed in Fig. 1. At this movement of the cam 209 a projection 235 thereon engages the yoke |06 of the lever |05 and rocks the lever |05 slightly counterclockwise. This removes from the tripping toggle |01--I09 the biasing force of the springs 85 transmitted through the contact arm 30, the main operating toggle 93-95, the lever 89, the link |03 and the lever |05, consequently any force applied to operate the tripping toggle |01--I09 either as a result of operation of the trip device |33 in response to overload currents, or by operation of the handle 4| is absorbed by the cam 209 and tripping of the breaker is defeated.

In addition to preventing operation of the tripping toggle |01-I09 the cam 209 when moved to its locking position beneath the yoke |09 acts also to prevent opening of the contact arm and contact. When the cam 209 is operated it locks the lever |05 against clockwise movement. Since the lever |05 is held against movement it follows that the lever 89 through the link |03 is held immovable. With the lever 99 held against movement and the force of the springs 35 and the springs 53 and 83 restraining the main operating toggle 93-95 in the over` center position it can be seen that a substantially solid linkage is effective through the operation of the cam 209 to maintain the contacts closed.

When it is desired to restore the circuit breaker to its normal functions the knob 233 is released and the spring 23| shifts the linkage 220 toward the left rocking the cam 209 counterclockwise. As the cam frees the yoke |03 the spring |29 immediately sets the tripping toggle |01|93 overcenter to the position shown without tripping the breaker.

Figs. 3, 4 and 5 illustrate another embodiment of the invention. In the case of ordinary shocks below a predetermined force the tension of the springs 35, 53 and 93 is sufficient to hold the main operating toggle 33-95 overcenter above the center line 99|0| and thus prevent accidental opening of the breaker due to Jars or shocks which might otherwise jar the toggle 93-95 overcenter in a direction to permit opening of the contacts.

A very heavy shock above the predetermined force might however cause the toggle 93-95 to break overcenter below the line 99| 0| and cause interruption of the power supply at a vital moment even though the previously described locking mechanism is effective to prevent operation of the tripping toggle |01| 09.

The purpose of the embodiment of the invention shown in Figs. 3, 4 and 5 is, therefore, to positiveLv lock the main operating toggle 93-95 as well as the tripping toggle |01--I09 against operation and thus positively lock the contacts in their closed circuit position. This embodiment of theinvention is illustrated as applied to the previously described circuit breaker mechanism and corresponding parts thereof have been given the same reference characters.

It will be remembered that after the breaker has been tripped and moved to the open circuit position either in response to an overload current or manually, the contacts are reclosed by operation of the contact closing lever |45 (Figs. l and 3)'. In accordance with the embodiment shown in Figs. 3, 4 and 5 the contacts are adapted to be locked in the closed position by interposing a locking member in the return path of travel of the closing lever thus positively holding the toggle 93--95 overcenter in the position where it isv effective to positively lock the contacts in closed position.

The locking member comprises a lever 231 (Fig. 3) pivotally supported on a stud 239 mounted in an upwardly extending portion 240 of the frame member I5. The lower portion 24| of the lever 231 is formed at an angle to the main body of the lever and is adapted, when operated, to engage a roller 243 rotatably mounted on a stud 245 projecting laterally from the closing lever |45. The lever 231 comprises a longer lever which iny v f 52,388,403

cludes the angular portion 24|, and a shorter le'- ver 241 disposed on the opposite side of the frame I8. The levers 231 and 241 are rigidly connected by a cross member 248.

The lowerend of the lever 241 is rounded and is adapted to engage a curved extension 25| of the yoke |84 connecting the sides of the previously described link^|83 for the purpose offpreventing operation of the tripping toggle H11-|08 as will be more fully brought out later.

ing lever clockwise to its closing position. Near the end of this movement the beveled end ,of the lever 231 assumes its position in the path of the In order to operate the locking' lever 231 there` is provided a pull rod assembly 253 which includes a rod 255 slidably and rotatably mounted in openings in an extension of the linsulating plate 228 and in the base II of the breaker, The rod 255 extends to the left (Fig. 3) of the base I and has a collar 251 secured on the end thereof. A restoring spring 258 is compressed between the collar 251 and a washer 28| disposed against the base` I I.

'I'he pull rod 255 is operatively connected to the locking levers 231-241 by means of a member 283 which is movable longitudinally with the rod 255 but which vpermits rotation of the rod therein. 'I'he member 283 is disposed between the upper ends of the levers 231 and 241 and is provided with an open slot 285 in the lower part thereof which engages a pin 281 mounted in the upper ends of the levers 231 and 241.

The member 283 is mounted on a reduced portion of the rod 255 and a sleeve 288 is secured to the reduced portion between the base and `the member 283 to prevent movement of the member 283 axially on the rod but which at the same time permits rotation of the rod 255 relative to the member. 'I'he sleeve 288 also acts to limit the unlocking movement oi' the rod assembly. Washers 21| and 213 are provided to absorb the thrust wear betwen the sleeve 288 and the base and the member 283. An operating knob 215 is secured to the outer end of the pull rod 255.

Assuming the breaker to be in an open position and that it is desired to close the contacts and lock them in closed position. The operator first closes the breaker by rotating lthe handle 4| in closing direction. This movement, as previously described, rotates the closing lever in a clockwise direction through the agency of the crank arm |44 (Fig. l), the link |5| and the roller |53. Clockwise rotation of the closing lever |45 engages the roller |55 with the toggle 83-85 and straightens this toggle thereby closing the contacts. While holding .the closing handle in closed position the operator grasps the knob 215 and draws the rod 255 outwardly, i. e., toward the right (Fig. 3).

This movement of the pull rod due to the connection 285-281 rocks the levers 231 and 241 clockwise about their common pivot 238. At this movement the rounded lever end of the lever 241 engages the extension 25| of the yoke |04 and prevents operation of the tripping toggle |||1 |88 by preventing clockwise rotation of the lever |05. Thereafter the beveled end of the lever 231 moves into the path of the roller 243 thus holding the closing lever |45 in its operated position.

If the breaker is already closed and it is desired to lock it in closed position the only operation required is to draw the rod to locking position. In this condition of the breaker the closing lever occupies the position in which it is shown in Figs. 1 and 3, and clockwise movement of the lever` 231 engages the angular portion 24| thereof with the roller 243 and rotates the closroller thus retaining thecloslng lever in the operated position.

After the pull rod 285 has been drawn out to its locking position it is desirable to lock it against the unlocking inuence of the spring 25s. '.L'his is accomplished by rotating the pull rod 25o' in a clockwise direction (Figs. 4 and 5) after it is moved to locking position. This movement engages a locking member 211 (Figs. 3 and 5). secured 'to the rodv255. with a notch 218 in a projection 28| of a fixed plate 283 mounted on a barrier 285 disposed between'adjacent poles oi the breaker. A member 281"integral with the member 2-11 engages the under side of the pro- Jection 28|, tolimit the unlocking rotation of the pull rod 255. AThe locking rotation of the rod is limited-by engagement of the locking member 211 with the 'upper edge of the extension 28|.

1n order to unlock the pull rod 255 it is first pulled out slightly to disengage the member 211 clockwise (Figs. 4 and 5). A pointer is provided on the knob 215 and an index plate 288 is secured to the insulating -plate 228 to indicate the locked and unlocked positions of the rod 255."

After the rod 255 has been unlocked it may be released and the spring 258 will restore the rod and the levers 231 and 241 to their ineffective positions. v As soon as the lever 231 clears the roher 243 the previously described spring |58 acts to rock the closing lever |45 counterclockwlse to its normal position.

Under normal conditions the circuit breaker is trip free of the handle, that is, if the breaker should ber closed against an overload it will immediately trip open even though the handle is held in the closed position. The circuit breaker may, however, be closed against an overload and locked in the closed position by proper manipulation of the locking device and the operating handle.

It will be remembered that when the circuit breaker is tripped open either manually or in response to an overload current the linkage including the lever 88, link |83, lever |05 and the tripping toggle H11-|08 (Fig. 3) is automatically reset to its normal position. In order to close and lock the breaker against an overload the pull rod 255 is first drawn outwardly rocking the levers 231-241 clockwise far enough to engage .the lever 241 (Fig. 3) with the projectionv 25| of the yoke |84 thus locking the tripping toggle against operation to trip the breaker when the `contacts are closed. The operating handle |4I is then rotated in closing direction, operating the closing lever |45 to close the contacts in the previously described manner. The pull rod 255 is now drawn outwardly to full locking position. This completes the clockwise movement of the levers 231-241 and engages the lower portion 24| ,thereof with the roller 243 to positively lock the contacts in their closed position.

Having described several embodiment of the n We claim as our invention:

1. A circuit breaker comprising a contact inember movable to an open position and to a closed position, a toggle operable to cause an opening movement of said contact member, means operable solely to move the contact member to closed position, and a pivoted lever having a part engageable with a part movable with said toggle and a part engageable with the closing means for moving said closing means to close position to prevent opening movement of the contact member.

2. A circuit breaker comprising a contact member movable to an open position and to a closed position, atoggle 'operable to cause an opening movement of said contact member, a closing lever operable to move the contact member to closed position, a pivoted member engageable with a part movable with the toggle to prevent operation of said toggle, said pivoted member having a part engageable with the closing lever to move said lever to closed position and to hold said closing lever in closed position, and manually operable means for operating the pivoted member.

3. A circuit breaker comprising a contact member movable to an open and to a closed position, a linkage operable to initiate an opening movement of the contact member, means engageable with a part of said linkage to prevent initiation of an opening movement of the contact member, closing means engageable with another part of said linkage to move the contact member to closed position, and means operable to hold said closing means in engagement with said linkage.

4. A circuit breaker including separable contacts, operating mechanism for said contacts including a manual operating member operable to cause opening of the contacts, a linkage for holding the contacts in closed position independently of said manual operating member, said linkage including a toggle operable to cause opening of the contacts, said manual member also being operable to close the contacts, a trip device operable in response to predetermined abnormal circuit conditions for operating the toggle to cause opening of the contacts irrespective of the position of the manual operating member, and manually operable means engageable with a part of said linkage for positively holding the contacts in closed position and also for preventing operation of said toggle by said trip device.

5. A circuit breaker comprising separable contacts, operating mechanism for said contacts, said operating mechanism including a manual operating handle movable in one direction to cause opening of said contacts and in another direction to close said contacts, a linkage for holding the contacts in closed position independently of said handle, said linkage including a toggle operable by said handle to cause opening of said contacts, current responsive means for operating said toggle to open the contacts Uli irrespective of the position of the handle, and locking means settable to a locking position in which it prevents operation of the toggle by said handle and also by said current responsive means and also positively locks the contacts closed.

6. A circuit breaker comprising a contact member movable to an open position and to a closed position, a toggle operable to initiate a movement of the contact member to open position, closing means comprising a lever operable solely to move the contact member to closed position, manually operable means movable to an intermediate posi- `tion wherein a portion thereof engages a part at all times movable with said toggle to prevent initiation of an opening movement oi' the contact member, said manually operable means being movable to a locking position wherein said portion thereof engages a part movable with the toggle to prevent initiation of an opening movement of the contact member and another portion thereof engages said closing lever to positively hold said contact member in closed position.

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 normally restraining said one end of said toggle in operative position, a pivoted operating lever operable solely to actuate said toggle to move said switch member to closed position, a trip device operable to cause said linkage to release said end of said toggle and thereby cause movement or the switch member to open circuit position, said linkage and said one end of said toggle being automatically reset to normal position following tripping of the breaker, and manual means for preventing operation of said linkage and release of said one end of said operating toggle when the switch member is being moved to closed position.

8. 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 normally holding said one end of said toggle in operative position, an operating lever operable solely to actuate said toggle to move said switch member to closed position, a trip device operable tocause said linkage to release said end of said toggle and cause movement oi the switch member to open position, said linkage and said one end of said toggle being automatically reset to normal position following tripping of the breaker, and manually operable means engageable with said linkage to hold said one end of said toggle in operative position while the breaker is being closed.

JOHN W. MAY. WILLIAM H. STUELLEIN. MERL E. HORN.

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