US2367920A

US2367920A - Circuit breaker

Info

Publication number: US2367920A
Application number: US423368A
Authority: US
Inventors: Albert H Baylis
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1941-12-17
Filing date: 1941-12-17
Publication date: 1945-01-23
Anticipated expiration: 1962-01-23

Description

Jan. 23, 1945.

BYLIS 2,367,920

C IRCUIT BREAKER Fi1ed Dec. 17] 1941 I5 Sheets-Sheet l MMM Patented Jan. 23, 1945 t CIRCUIT BREAKEB Albert H. Baylis, North Irwin, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application December 17, 1941, Serial No. 423,368 15 claims. (Cl. r11-.97)

The invention relates to circuit breaker systems and more particularly to an interlocking arrangement for interlocking a plurality of circuit breakers.

One object of the invention is the provision of an electrical system having a plurality of circuit breakers and a novel electrical interlock arrange? ment for the breakers to prevent closing of an open breaker while another breaker is in closed position and in which mechanical means is provided to prevent the closed breaker from tripping out due to a loss of control energy in the interlocking circuit.

Another object of the invention is the provision of a plurality of circuit breakers with an improved electrical interlock which prevents closing of one circuit breaker while the other is closed and in which mechanical means prevents the functioning of the interlock associated with the closed breaker due to loss of control energy for the interlock oircuit.

Another object of the invention is the provi;

l with means for preventing operation of its own electrorcsponsive means when in closed position.

Another object of the invention is the provision of an improved control device for a circuit breaker embodying an electroresponsive trip means adapted to be controlled from a second breaker y to effect tripping of the circuit breaker if said breaker is operated to closed position when the second breaker is closed.

Another object of the invention is to provide an improved control device for a circuit breaker comprising an electroresponsive trip means which is controlled by a second breaker when the second breaker is closed to prevent closing ofthe rst breaker, and which is provided with a mechanical member to positively prevent operation of the trip means when the iirst breaker is in closed position.

Another object ofthe invention is the provision of a circuit breaker embodying an auxiliary trip Idevice biased to cause tripping of the breaker wherein the trip device is prevented from operating by an electromagnetic means controlled y by a second breaker and in which a mechanical member is operated by the breaker when the breaker is closed to prevent Operation of the auxiliary trip device.

The novel features that are considered char- 4 acterlstic of the invention are set forth in partlcular in the appended claims. The invention litself, however. both as to structure and operation, together with additional objects and ad- 'l0 and a screw 1I.

vantages thereof, will be best understood-from the following description of a single embodiment thereof when read in conjunction with the accompanying drawings in which:

Fig. 1 is a side elevational view of one three pole circuit breaker embodying the interlocking arrangement of the invention.

Fig. 2 is a vertical sectional view through the center pole of the breaker.

Fig. 3 is a diagrammatic View showing two circuit breakers interlocked by the interlocking arrangement of the present invention and shoW ing the interlock control circuit, and

Fig. 4 is an enlarged sectional view taken on the center line of the resilient linkage of the interlocking mechanism.

The two electrically interlocked circuit breakers are of identical construction and hence the details of construct-ion of one will be sulcient.

Referring to Fig. 2 of the drawings which shows one of the electrically interlocked breakers, the circuit breaker is provided with an operating mechanism common to all of thev poles which is v mounted in a U-shaped main frame I6 comprising through anv opening in the connector 2l and through openings in the frame members l1 pivot- .ally supports a pair of arms 3l having their free 4ends integral with a contact arm 30 for,the center pole. The contact arms 3U (Fig. 1) for the outer poles are identical with the arm 30 for the A center pole but'are not provided with arms 3l.

The contact arms 30 for the outer poles are rigidly secured tc a tie bar 61 which extends across all of the poles and which is clamped to the center pole contact arm 30 by means of a split clamp Rectangular tubes 69 of insulating mat'erial between the tie bar 61 and contact arm 30 for the several poles serve to insulate the three movable contact arms and their associated contacts from the tie bar 61.

TheA movable contact structures and thesta.-

' tionary contacts for the several poles are alike able arcing contact member 55 is pivoted on a pivot pin 51 supported in projections 59 of the arm 30. The main movable contact member 41 carries a contact 33, and a contact 35 is secured to the arclng contact member 55. These

contacts

33 and 35 are adapted to engage respectively :

fixed contacts

33 and 31 secured on a conductor 4I which is in turn secured to the base by means of bolts 43. 'I'he conductor 4| extends upwardly and is bent at right angles, the bent portion extending through an opening in the base Il to form a terminal connector 45.

A spring 53 compressed between a spring seat on the Contact arm 30 and a spring seat on the main contact member 41 provides Contact pressure for the main contacts 33--39 when the contact arm is in the closed position. Contact pressure for the arcing contacts 35-31 is provided by a spring 53 surrounding a rod 6l pivotally connected to the arcing contact member 55 and slidable through an opening in a spring seat on the contact arm 30. The spring 53 `is compressed between washer 65, seated on a shoulder on the rofl tt, and the spring seat on the contact arm .lloc rod 6| has a nut 15 on the outer end thereof which acts to limit counterclockwise rotation of the arcvl ing contact member 55 about its pivot when the contact arm 3B is moved to open the contacts. Counterclockwise movement of the main contact member 41 is limited by a projection 13 thereon striking the body of the contact arm Siti. The adjustment of the nut 15 on the rod'lii is such that the arcing contacts 35-31 open after the main contacts 33--39 open during an opening operation of the circuit breaker and close before the main contact closes during a closing operation.

When the Contact arm :ill is operated to or 1 the contacts, the arc across the 35--31 resulting from the rupture of the c is drawn into an arc extinguisher indica erally at 1B where it is cooled and extingui led. Any suitable arc extinguisher may be employed, the one illustrated comprising, generally, a stack of slotted magnetic plates disposed adjacent the paths of travel of each of the arcing contacts 35. The plates serve to drawA the arc towards the ends of the slots where it is broken up into a plurality of short arcs which are quickly cooled and extinguished.

The movable arcing contact member 55 is connected by a flexible shunt conductor 11 to the main contact member 41 and another flexible shunt conductor 13 connects the main contact member 41 to the connector 21. The connector 21 for the center pole is secured to the-cross member I3 of the frame I5 by the bolts 23, and the connectors 21 for the outer poles are bolted to the base |l with a spacer 23 (Fig. 1) between the base and each of these connectors in order to align the members 21 of the outer poles with the corresponding members 21 for the center pole. A conductor Il (Fig. 2), secured to the connector 21 by means of bolts 14 extends downwardly therefrom and is bent at right angles. The horizontally disposed portion oi the conductor extends between the legs of a U-shaped tripping magnet core and projects through an I opening in the base Il where it forms a terminal connector 83 which. together with the terminal connector 45, serves to connect the pole of 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 traced.

This circuit extends from the terminal connector 45 through the conductor 4|, the main contacts 33-39, the main contact member 41, the iiexible shunt conductor 19, the connector 21, the conductor 8| to the terminal connector 83. The circuit for the arcing contacts 31--35 extends from the terminal connector 45, through the conductor 4|, the arcing contacts 31--35, the flexible shunt conductor 11, the main contact member 41 and through the previously described circuit to the terminal connector 83.

The contact arms 30 are biased in a clockwise or opening direction by :means ci a pair of springs 85 (Figs. 1 and 2). These springs are tensioned between the center pole contact arm 30 and a fixed pivot supportePl in the mein frame it l. the closed position. t e t if., if; l "i contact arm an consequently tact arms are re i Contact position linkage mechani opening of the conte forms a part of the mism.

This collapsible linkage inclu lever piv otally mounted on a fixed pivot i supported the ina-in frame it. The lever 89 compi oi." levers rigidly connected by an bar l il, and is operatively connected to the support arms 3l of the center pole contact arm 3M by a main operating toggle comprising

toggle links

93 and 95. The toggle link @t has one end pivoted on a pin lili supported on 'the lever S3 and the lint: 95 is pivoted on a pivot pin B9 on the arm 3|. The

links

93 and 95 are pivotally connected by a knee pivot pin 9i. The toe? fik dt coin o: c

ating noecliam pivot tid by' a :volte provided wil pri |25 andl t...,.e limit. ID'l comp pair oi l1 ii by f volte @it ha 50 l secured an extension g The toggle links |01 and |09 are pivotaliy connected by a linee pivot pin III. The purpose of the extension |24 is to cooperate with a part (notJ shown) connected to a manually operable handle i4| to manually trip the breaker in a manner to be more fully described later. The lever |05 and the link |03 each comprise a pair of members rigidly connected by yolies substantially as illustrated.

The linkage just described serves to releasably hold the Contact assemblage including the movable contacts for all of the poles of the breaker in closed contact position. In the closed position, the main operating toggle 93-95 is overcenter above a line through the center of the pins 99|||I, and a second toggle, one link of which comprises the overcenter links 93-95 and the other link of which comprises the lever 89, is overcenter above a line through the center of the

pins

89 and 3|. The overcenter movement oi' the main operating toggle 93-95 is limited by the projecting end of the link 93 engaging the cross bar ||5 of the link S5.

With the main operating toggle 93-35 and the toggle comprising the links 93-35 and the lever 89 in the overcenter position, as shown in Fig. 2, the Springs 85 bias the lever 89 in a clockwise direction. Movement of the lever 89, however, is normally prevented by the tripping toggle |01-|09 which is overcenter to the left of a line through the center of the iiXed pivot H3 and the point of connection of the toggle link |01 with the lever |05. The toggle |01- |09 is biased to its overcenter position by a spring |28 tensioned between the yoke ||9 and the nxed pivot ||3. The overcenter position of the tripping to"- gle |01-l 09 is adjustably determined by the projection of the yoke |23 engaging an adjusting screw |29 in the cross member 25 of the frame. The tripping toggle |01- |09 in its overcenter position, acting through the lever |05 and the link |03, prevents clockwise movement of the lever 89 and consequently holds the movable contact assemblage in the closed ucontact position against the biasing influence oi the springs 85.

The tripping toggle |01-|09 is adapted to be moved overcenter outwardly in a direction to cause its collapse to effect opening of the contacts by means of a current overload trip device indicated generally at |33 (Figs. l and 2). The trip device is operable in response to overload currents in the circuits of the breaker to actuate a trip rod |35 and cause collapse of the tripping toggle I 01-I09. The trip rod |35 is slidable vertically through a shunt trip coil (not shown) enclosed in a casing |38 attached to the main frame I6. The shunt coil is adapted to be energized from a suitable source and in a manner well known in the art, to operate the trip rod and trip the breaker from a remote point.

When operated either by the shunt coil or by the current overload trip device |33, the trip rod |35 is thrust upwardly and strikes the projection |21 of the yoke |23 and rocks the toggle link |09 clockwise about the xed pivot H3. This movement of the link |09 causes collapse of the tripping toggle |01-i 09 permitting clockwise movement of the lever S9 which permits the springs 85 to rock the movable Contact assemblage clockwise'to open the contacts.

The main operating toggle 03-95 does not immediately collapse but the force oi the springs t1;- applied through the contact arms Elfi-3| and the main operating toggle causes collapse of the toggle comprising the links 93-95 and the lever 85 which results in clockwise movement of the lever 09; This movement is transmitted through the link |03 and the lever 55 to complete the collapse of the tripping toggle |51 |09.

The clockwise or opening movement of the contact arm 30 is larrested by projections (not shown) thereon striking portions |31 of the frame members Il of the main frame I6. At this time the rebound of the inertia of the main operating toggle 93-95 and the parts of the linkage 89, |03 and |05 starts the main operating toggle overcenter in a direction to cause its collapse. By the time the knee pin 91 of the toggle has passed overcenter below the line 99|0| the weight of the parts acts to complete the collapse of the toggle 93-95 and causes the-linkage 89, |03, |05 andthe tripping toggle |01-|09 to be automatically reset to their normal position. The main operating toggle 93-95 remains in collapsed condition :mtil the contacts are closed.

The contacts are closed manually by operation of the previously mentioned handle |4|. The handle is rotatably mounted in a bracket |43 of insulating material secured'to the outer end of the main frame I6. operatively connected to the mechanism (not shown) `operated -by the handle is a link |5|. The lower end of the link |5| is recessed and straddles a pulley-shaped member |53 mounted on a cross member |41 rigidly connectingthe outer ends of a pair of spaced contact closing levers |45. These levers are dis- Dosed on the outside of the frame I6 and are pivotally supported on the ends of the fixed pivot 9| which project beyond the frame members I1. The inner ends of the lever |45 are rigidly connected by a cross member |49. Spaced projections |52 extending from the center portion of the cross member |49 support a pivot pin |51 upon which is rotatably mounted a roller |55.

The contacts are closed manually by clockwise rotation of the handle |4|. This movement of the handle, through connections (not shown) thrusts the link |5| downwardly and due to its engagement with the member |53, rotates the 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 main operating toggle 93-95 and moves this toggle to its overcenter position. Since at this time the tripping toggle |01-|09 has been restored to its overcenter position, rotation of the lever 89 is prevented and consequently the force applied by the `roller |55 to straighten the toggle 9395 rotates the contact arm 30 counterclockwise to close the contacts and to tension the springs 05. The clockwise movement of the closing lever |45 moves the toggle 93-95 overcenter above the line 99|0| so that the contacts are held in the closed position until the breaker is again tripped.

The closing lever |45 may be operated to automatically close the contacts through the agency of a motor |39 (Fig. 2) mounted on a plate attached to the side of the frame i6. The motor |39 may be energized from any suitable source. When energized, the motor is adapted, through a suitable driving connection, to rotate a crank disc |30. This disc carries an anti-friction roller |3| which engages a cam fac-e |32 on an arm |34 secured to one side of the closing lever |45 and rotates the arm and the closing lcv-er |45 clockwise to effect closing of the contacts in the previously described manner. As soon as the roller |3| passes out of engagement with the arm |34, the spring |59 acts to restore the 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 rotation-of the handle |4| through a small angle in a counterclockwise direction from its neutral position. When the handle is rotated in tripping direction, a projection (not shown) on the link |5| engages the extension |2| on the yoke ||9 of the toggle link |01 and rocks the link counterclockwise about its point of pivotal connection with the lever |05. This moves the tripping toggle |01-|09 overa-enter in a direction to cause its collapse and effects opening of the contacts in the previously described manner.

As previously stated, the trip rod |35 is operated to eiect tripping of the breaker by means of a. current responsive trip device |33. There is a trip device |33 provided for at least two of the poles oi' the breaker but since the trip devices are alike only the one for the center pole will be described.

Normal rated current flowing through the circuit of the breaker, including the conductor 8|, causes slight energization of the magnet |5| but not sufficient to overcome the tension of the springs |9|. Upon the occurrence of an overload current above a predetermined value in the circuit of any pole, the flow of current through the corresponding conductor 8| causes energizetion of the magnet suflicient to overcome the springs |9| and attract the armaturev |19 rock- `ing the trip lever |13 counterclockwise. At this movement of the trip lever |13; the screw IBI rotates the arm |85 and the trip bar |81 in a clockwise direction and thrusts the trip rod |35 upwardly to trip the breaker in the previously described manner.

Figure 3 illustrates diagrammatically an elec` trical control system wherein two circuit breakers ot the type hereinbefore described indicated generally at A and B are utilized to selectively connect independent supply circuits 3 and I to a load circuit 5. In such systems it is desirable to prevent closure of one breaker while the other is closed to avoid connecting both source circuits to the load circuit at the same time. It is also desirable to prevent the closed breaker from-tripping out in response to a loss of energy in the control circuit.

Each of the breakers A and B is provided with an interlocking device indicated generally at 205e. and 200b (Fig. 3). These interlocking devices are identical and therefore only one will be described.

Each 0I the interlocking devices includes an elec- 75 tromagnet 209 (Fig. 1) comprising an E-shaped core 2H rigidly mounted between the legs or a U-shaped frame 2|3 secured to the base adiacent the left hand pole as viewed from the front of the breaker. Each of the two cuter legs of the magnet core is surrounded by a coil 2 l1, the two coils being connected in series and forming the energizing winding of the electromagnet. An armature 2 9 is mounted between a pair of spaced arms 22| pvotally supported on a pivot pin 223 mounted on the U-shaped frame 2|3. The iower end of an extension 225 rigidly secured to the free ends of the arms 22| is provided with an ear 221 in which is mounted an adjustable screw 229. The screw 229 is in alignment with an arm 23|, similar to the previously described arms |55, secured to the 'trip bar 151 so that upon ccunterclockwise movement ci the spaced arms 22| and the extension 225, the screw will rock the trip bar clockwise to trip the breaker in the previously described manner.

The arm 22h-225 is connected to the tie bar t1 of the breaker contact assemblage by means of a resilient linkage 245(Figs. l. and fi). The one end of the linkage is pivotally connected to the arms 22| by a pivot pin 233 mounted in the arms and the other end of the linkage is pivotally connected to the tie bar 51 by a pivot pin 235 projecting from the end of the tie bar.

The resilient linkage 245 includes a cylinder 25| (Figs. 1 and 4) provided with a transverse opening at one end through which the pivot pin 233 extends. A cylindrical sleeve 255 (Fig. 4) iltting in the end of the cylinder 25| which is connected to the spaced arms 22| is retained in place by the pin 233 which extends transversely through openings therein. A shoulder rod 251 having its upper end threaded into a connector 231 projects into the cylinder 25|. The connector 231 has a transverse opening therein to receive the pin 235 which projects from the end of the tie bar 51 and thus serves to connect the upper end of the link-age 245 (Fig. 1) to the tie bar. A lock nut 239 is provided to lock the rod 251 and connector 231 in their adjusted po sitions. The other end of the rod 251 is provided with a screw 21| whose head is slidable in the sleeve 255. A spring 213 is compressed between a washer 215 seated against the inner end of the sleeve 255, and a washer 211 seated against the inner shoulder of the cylinder 25|. The construction is such that the head of the screw21| engages the washer 215, and the shoulder on the rod 251 engages the washer 211, so that the compression of the spring 213 in the cylinder will be increased when the rod 251 and the cylinder 26| are moved in either direction relative to each other. I

As shown in Fig. 4. the spring 213 is given an initial compression, the expansion force of which presses the washers 215 and 211, respectively, against the sleeve 255 and the inner shoulder of the cylinder 26|. The interlock device 200 is shown in Fig. 1 in the normal .position, that is, with the circuit breaker contact assemblage in the closed contact position and normal control voltage applied t0 the coils 2|1 of the electromagnet 209 through a control circuit which will be described later. In this c0ndition, the linkage 245 is in tension, i. e., the rod 251 is drawn partway out of the cylinder 25| giving the spring a greater compression than its initial compression. The tension of the linkage 245 in these circumstances, biases the arm 22|- 225 and the amature 2|9 in a counter-'f clockwise direction or to unattracted position. Normal voltage in the control circuit, however energizes the windings 2| 1 of the electromagnet 209 sufficiently to hold the armature 2|9 and the trip arm 22|225 in the attracted positions against the bias of the resilient linkage 245 to prevent tripping of the breaker by the interlock trip arm 22|-225.

Means is also provided to prevent tripping movement of the arm 22|-225 due to deenergization of the magnet 209 upon the loss of control voltage when the main breaker contacts are in closed position. This means comprises a bell crank lever 219 (Fig. 1) which is pivotally supported on a pivot pin 28| mounted in the upper ends of a pair of brackets 283 (only one being shown) secured to the sides of the U-shaped frame 2|3. An open slot 234 in the end of the upwardly extending arm of the lever 219 embraces the pin 235 and transmits the movement of the tie bar 61 to the lever 219. The other end of the lever 219 is formed in the shape of a yoke 285 in which is mounted an adjustable screw 281 which is adapted to cooperate with a projection 289 of the interlock trip arm 22| when the main'breaker contacts are in the closed contact position to prevent tripping movement of the arm 22|225 due to loss of control voltage of the interlock control circuit.

Referring now to Fig. 3, it can be seen that a circuit breaker of the type previously described and indicated schematically lat A is closed connecting a main source circuit 3 to a load circuit 5, and that a second circuit breaker B is open disconnecting an auxiliary source circuit 4 from the load circuit 5.` The breakers A and B are provided with auxiliary contacts 24|a and 2Mb, respectively. The contacts 24|a control the energization of the interlock magnet 2091 for the breaker B, and the contacts 24|b control the interlock magnet 209a for the breaker A. It can also be observed that the contacts 24|a and 24|?) are open when their corresponding breaker is closed and closed when the corresponding loreaker is open. Thus the magnet 299ais energized when breaker B is open land the magnet 209D is energized when breaker A is open. Conversely the magnet 20911, is deenergized when breaker B is closed and magnet 2091 is deenergized when breaker A is closed.

The control circuits for energizing the magnet 209a extends as follows: From a control supply conductor 241 through a conductor 249, auxiliary contacts 24|b, a conductor 25|, coils 2|1 of the magnet 209a, a conductor 253 to the supply conductor 255. Similarly the energizing circuit for the magnet 209i; extends from the supply conductor 241, through a conductor 251, auxiliary contacts 24|a, conductor 259. coils 2I1 of the magnet 2991i and conductor 262 to the control supply conductor 255.

When the circuit breaker is in the open position, i. e., with the main contact assemblage including the tie bar 61 in the open position the arm 22|225 is retained by the resilient linkage 245 in the position shown in Fig. 1 with the armature 2|9 in contact with the core 2| I. Tile linkage transmits the clockwise or opening movement. of the tie bar 61 to the spring 213. During the latter part of this movement the rod 261 telescopes into the cylinder 26| placing the linkage in compression, thereby holding the arm 22|-225 in the position shown in Fig. l and permitting overtravel of the parts `without subjecting them to undue strain. During the position,

movement of the contact assemblage to the open the bell crank lever 219 is rocked clockwise, due to the pin and slot connection 234-235, moving the screw 281 away from the projection 289.

Referring to Fig. 3, let it be assumed that the breaker B is in the open position, as just described, and that the breaker A is closed as illustrated in Fig. 1. It will be remembered that when the breaker was tripped open, the tripping toggie I 01|09 was momentarily collapsed permitting the springs to move the contact assemblage to the open position. Upon reaching the fully open position, the toggle 93-95 collapsed and the linkage including the lever 89, link |03, lever |05 and the tripping toggle [D1- |09 was restored to the normal position. The magret 209D is deenergized due to the opening of contacts 24 |a of breaker A.

If, with the breaker B in this condition, the handle 4| is rotated in closing direction, the closing lever |45 will be rotated in clockwise direction to eifect straightening of the operating toggle 93-95 as previously described. During the ilrst part of this movement, the contact arm 30-3| will Ibe. rocked slightly in closing direction since the tripping toggle |01-I09 is overcenter or in toggle at this time. The slight movement of the contact arm and the tie bar 61 again places the resilient linkage 245 in tension, thus transmitting the movement of the tie [bar to the trip arm 22 |-225. This rocks the trip arm counterclockwise and by means of the screw 229 actuates the trip -bar |81 which in turn thrusts the trip rod |35 upwardly and starts the tripping toggle IUT-|09 overcenter. The springs 85 then act to move the contact arm to the fully open position and to complete the collapse of the tripping toggle in the previously described manner. It can be seen, therefore, that since neither the breakers A or B can be closed when the other is closed, the load circuit 5 may be connected to only one of the

source circuits

3 or 4 at a time.

As previously described, the closed breaker may Ibe automatically opened in response to an overload condition in the breaker. In this event either Ibreaker may be manually closed since the control Imagnets 209e and 209b are both energized over their respective control contacts 24|b and 24|a. Energization of the magnet will attract the armature 2|9 with sufllcient force to prevent tripping movement of the interlock trip arm 22l-225. The tripping toggle |01| 09 will, therefore, remain in the overcenter restraining position and the breaker may be closed in the usual manner. As the contact assemblage including thetie bar 51 (Fig. 1) is moved to closed position the linkage 245 is again placed in tension.

It was mentioned previously that it is desired to prevent the closed breaker from tripping open due to failure of energy in the control circuit 241-255 With the rbreaker in closed position. the tension of the spring 213 (Fig. 4) of the ilexilble linkage 245 is overcome by the attraction ofthe magnet 209 (Fig. l) which prevents tripping operation of the interlock trip arm 22 |-225. If the source of control energy in the circuit 24T-255 were to fail the linkage 245 ordinarily would immediately -actuate the arfm 22I-225 to trip the breaker. Means comprising the bell crank 219 is provided to prevent such undesira-ble tripping action. From Fig. 1 it can 'be seen that when the breaker is in the closed position, the bell crank lever 219 is positively held in the circuit controlled by the position shown due to the pin and slot connection 234-235. With the bell crank 21B held in its Fig. 1 position, the screw 281 positively holds the arm 22 l--225 in the attracted position against the tension of the flexible linkage 245 irrespective of the energized condition of the magnet 209.

From the foregoing description, it can be seen that there is provided a system of electrically interlocking two remotely located circuit breakers in a manner which permits only one of the circuit breakers to be closed at a time. There has also been provided a simple and effective mechanical means for preventing tripping out oi the closed breaker due to loss of energy in the interlocking control circuit.

It is obvious that additional source circuits may be selectively connected to the load circuit and the circuit breakers for controlling the additional circuits may be interlocked with the other breakers by extending the energizing circuit for the control magnet for each breaker serially through auxiliary contacts on all of the other breakers'.

Having 'described a preferred embodiment oi the invention in accordance with the patent statutes, it is to be understood 'that various changes and modifications may'lbe made therein without departing `from some oi' the essential features of the invention. It is, therefore, desired that the appended claims be given as reasonably broad interpretation as the prior art permits.

I claim as my invention:

1. A circuit breaker comprising relatively movable contacts, operating mechanism for said contacts, a trip device operable to cause opening of the contacts, a second device operable to cause opening movement ci said contacts, said second device when operated preventing closing of the breaker, spring means for biasing said second device to operated position, an electromagnet operative when energized to prevent operation of said second device, said electromagnet when deenergized permitting operation of said second device, and means effective when said contacts are in closed position to positively prevent operation of the second device irrespective of condition of the electromagnet.

2. A circuit breaker comprising relatively movable contacts, operating mechanism for said contacts, a trip device operable in response to predetermined conditions in the circuit controlled f by the breaker to cause opening of the contacts, a trip mechanism including a resilient linkage operable during a closing-movement of the movable contacts to cause opening of the contacts,

an electromagnet having an armature operatively connected to the trip mechanism for restraining said trip mechanism when the electromagnet is energized, a control circuit including means op erated b y a second circuit breaker for'energizing the electromagnet when said second breaker is in open position and for deenergizing the electromagnet when the second circuit breaker is closed, and means eiective when the contacts of the first breake are in closed position to positively restrain the trip mechanism irrespective of the energized condition of said electromagnet.

3. A circuit breaker comprising relatively movable contacts, a switch member movable to open and close said contacts, operating mechanism for moving said switch member to open and to closed circuit positions, a trip device including resilient means operable if unrestrained during closing movement o! the switch member to cause opening movement of said switch member, an electromagnet responsive when energized to prevent operation of said trip device, said electromagnet when cleenergized permitting operation of the trip device to thereby prevent closing of the switch member, and means controlled by a second circuit breaker to control the energization of said electromagnet.

4. A circuit breaker comprising a switch member movable to an open and to a closed position, operating mechanism for moving said switch member to open and closed positions, a trip device including resilient means operatively connected to the switch member and operable during a closing movement of said switch member to initiate an opening movement of the f switch member, an electromagnet operable when energized to restrain the trip device and permit a complete closing movement of the switch member, means operable by a second circuit breaker to control the energication ci said electromagnet, and means operable when the switch member is in closed position to restrain the trip device independently oi' the eiectromagnet.

5. A circuit breaker comprising a switch member movable lto an open and to a closed position a trip device including resilient means operable during a closing movement of the switch member to initiate an opening movement of said switch member to thereby prevent closing of the switch member, an electromagnet effective when energized to prevent operation of said trip device, said electromagnet when deenergized permitting operation of the trip device to thereby prevent movement of the switch member to the fully closed position, means including a second y circuit breaker for controlling the energization of said electromagnet, and a current responsive trip device operable in response to predetermined conditions in the circuit controlled by the first breaker to cause opening movement of the switch member irrespective of the energized condition of the electromagnet.

6. In combination, a pair of circuit breakers, each of said circuit breakers comprising relatively movable contacts, operating mechanism including a toggle operable to cause opening of said contacts which toggle in the operated position prevents closing of said contacts, a trip device including resilient means operable to cause operation of said toggle, an electromagnet having an armature operatively connected to the trip device for restraining said trip device against operation by the biasing force of said resilient means, said electromagnet when deenergized releasing the trip device for operation, and means operable by one of the breakers when said breaker is operated to closed position to deenergize the electromagnet for the other breaker and permit operation of the trip device.

7. The combination with two supply circuits and a load circuit, of a. circuit breaker associated with each of said supply circuits for selectively connecting said supply circuits to said load icircuit, each of said circuit breakers comprising relatively movable 4contacts, operating mechanism including a member movable to a position to cause opening movement oi said contacts, said member when in said .position preventing closing of said contacts, meansbiased to cause movement of said member to said position, an electromagnet having an armature operatively connected to said means for holding the means in operative position against the biasing action, said electromaget when deenergized releasing the biased means for operation, means operable by one o! said breakers when said breaker is opascasafc 7 erated to closed position to effect deenergization of the electromagnet for the other breaker to thereby prevent operation of said other breaker to closed position, and means on each breaker operable when the breaker is in closed position to restrain the biased means independently of theelectromagnet.

8. The combination with a circuit to be ener? gized, a plurality of sources of energy therefor, and connecting means comprising a plurality of circuit breakers disposed between the circuit and each of the respective sources for selectively connecting said circuit to said sources, a device vfor each breaker operable to prevent closing of the associated breaker, an electromagnet associated with each device and operable when energized to prevent operation of said device, said magnet when deenergized permitting operation of its associated device, means on each of the breakers to control the energization of the electromagnet for the other of said breakers, and means on each breaker operable when said breaker is in closed position to positively prevent operation of the device independently of the electromagnet.

9. A circuit breaker comprising relatively movtacts including a toggle operable to cause opening of said contacts, a current responsive trip device operable in response to predetermined circuit conditions for operating said toggle, means including a resilient linkage for operating the toggle to prevent closing oi the contacts, an electromagnet energized under control of another circuit breaker and operable when energized to prevent operation of said means, and means operable when the nrst breaker is in closed position to positively prevent operation of said linkage independently of the electromagnet, said current responsive trip device being operable to cause opening of said contacts irrespective of the operative condition of the linkage.

l0. A circuit breaker comprising relatively movable contacts, operating mechanism for said contacts, a. member movable to a tripping Dosition to cause opening movement of said contacts, said member preventing closing of said contacts when in said tripping position, resilient means operable to bias said member in one direction during initial closing movement of the breaker and when the breaker is in the closed position and in the opposite direction when the breaker is open, an electromagnet operable when energized to prevent movement of said member to tripping position, said electromagnet when deenergized permitting movement of said member to tripping position, and means effective when said closing movement'of the breaker and when the breaker is in closed position, an electromagnet eiective when energized to prevent movement of the member to said position, and means efbreakers each having a member movable to a tripping positionto cause opening of the breaker and to prevent closing of the breaker, resilient means biasing said member in one direction during initial closing movement of the breaker and when the breaker is in closed position and in the opposite direction when the breaker is open, an electromagnet effective when energized to prevent movement of said member to tripping position, said electromagnet when deenergized permitting movement of 'said member to tripping position, means for energizing said electromagnet, means effective when the contacts are in closed position to prevent movement ofV said member to tripping position, and means on each breaker operable when the breaker is closed to effect deenergization of the electromagnets of the other circuit breakers.

13. A circuit breaker comprising relatively movable contacts, operating mechanism for said contacts, a member movablefto a tripping position to cause opening movement of said contacts, said member preventing closing of said contacts when in said tripping position, spring means for biasing salid member to tripping position, an electromagnet operable whenn energized to prevent movement of said member to tripping position, said electromagnet when deenergized permitting movement of said member to tripping position, and means effective when said contacts are in closed position to prevent movement of said member to tripping position irrespective of said electromagnet. f

14. Incombination, a plurality of circuit breakers each having a'member movable to a tripping position to cause opening of the breaker and to prevent closing of the breaker, spring means for biasing said member to tripping position, an electromagnet eiective when energized to prevent movement of said member to tripping position, said electromagnet when deenergized permitting movement lof said member to tripping position, and means eiective when said contacts are in closed position to prevent movement of said member to tripping position, means for energizing resilient means operable by said switch member for biasing said trip member to tripping position during the initial closing movement of said switch member and when said switch member is in closed position, an electromagnet having an armature operatively connected to Said trip member for holding the trip member against the biasing force of said resilient means, said electromagnet when deenergized releasing the trip member for movement to tripping position, and means operable by the switch member when said switch member is in the closed position to hold the trip member independently of the electromagnet.

ALBERT H. BAYLIS.