US2408199A

US2408199A - Circuit breaker

Info

Publication number: US2408199A
Application number: US410686A
Authority: US
Inventors: James M Cumming; Richard C Cunningham
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1941-09-13
Filing date: 1941-09-13
Publication date: 1946-09-24
Anticipated expiration: 1963-09-24

Description

Sept. 24, 19%.;

J.,M.CUMMING ETAL 2,408,199

CIRCUIT BREAKER Filed Sept. 15, 1941 2 Sheets-Sheet 1 WETNESSES: INVENTORS JamesM Cummin 2 R/ClyG/d C (unm'lgzzam Patented Sept. 24, 1946 UNITED STATES PATENT OFFICE CIRCUIT BREAKER James M. Cumming, Turtle Creek, and Richard C. Cunningham, East Mclieesport, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pin, a corporation of Pennsylvania Application September 13, 1941, Serial No. 410,686

17 Claims. 1

The invention relates to circuit breakers, and more particularly to high speed circuit breaker operating mechanisms of the pneumatic type.

High speed operation of circuit breakers is becoming increasingly important, and circuit breakers are now desired embodying operating mechanisms which are capable of quickly re- Versing the switching movement of the contacts in order to provide high speed opening of the contacts, and quick automatic reclosing of the contacts immediately after interruption of a short circuit. Automatic reclosing time can be materially reduced by quickly reversing the opening movement of the breaker to reclose the same immediately after interruption of the circuit, particularly if the reclosing movement is initiated before the breaker reaches full open position. It is also important that the breaker shall be opened quickly without substantial retardation in response to an overload. The movement of the contacts must be reversed quickly to opening movement without substantial retardation when the breaker is being closed or automatically reclosed against a fault, even though the closing air pressure is still being admitted to the operating cylinder.

An object of the invention is the provision of a circuit breaker embodying an operating mechanism operable by fluid pressure to close the breaker and having an improved construction which will permit quick reversal of operation of the breaker in either direction of movement.

Another object of the invention is the provision of a circuit breaker embodying an operating mechanism pneumatically operated to close or automatically reclose the breaker, and having means for causing quick and substantially unretarded opening of the breaker in response to predetermined abnormal conditions in the circuit even if the abnormal condition occurs at the instant the circuit is closed.

Another object of the invention is the provision of a circuit breaker operating mechanism which. is operated by fluid pressure to close or automatically reclose the breaker, and means for causing quick collapse of the closing fluid pressure in the operating cylinder upon the occurrence of predetermined abnormal conditions in the circuit to cause quick and substantially unretarded opening of the breaker in response to said condition even if the main inlet valve of the mechanism is open at the time.

Another object of the invention is the provision of a circuit breaker operating mechanism operated by fluid pressure to close or to automatically reclose the breaker and having an adequate fluid pressure exhausting means controlled by the circuit breaker tripping means to provide for quick and substantially unretarded opening of the breaker and produce the effect of trip free action without disconnecting the operating piston from the breaker.

Another object of the invention is the provision of a circuit breaker operating mechanism operated by compressed air to close or automatically reclose the breaker and having an improved air pressure exhausting means, for the operating cylinder, controlled by the circuit breaker tripping means so that a tripping impulse will always take precedence over a closing impulse thus providing the effect of trip free action without disconnecting the main circuit breaker operating piston from the breaker.

Another object of the invention is the provision of a circuit breaker operating mechanism which is pneumatically operated to close or automatically reclose the breaker and provided with a main exhaust valve of the piston type which is opened by air pressure under the control of a light pilot valve operated by the armature of the circuit breaker tripping means, whereby the exhaust valve is caused to open by air pressure in the operating cylinder at the same time the circuit breaker is unlatched or tripped, Without adding an appreciable load on the circuit breaker tripping coil.

Another object of the invention is the provision of a circuit breaker operating mechanism operable to close or quickly reclose the breaker by fluid pressure and having an exhaust passage larger than the main inlet passage and an exhaust valve controlled by the circuit breaker tripping means to provide trip free action, the exhaust passage being located in the operating cylinder so as to be closed by the main operating piston before it reaches the position at which fluid pressure is admitted for quick reclosure thus preventing exhausting of the reclosing fluid pressure and at the same time allowing a sufiicient time interval for the mechanical closing of the exhaust valve on a quick reclosing operation.

Another object of the invention is the provision of an improved circuit breaker operating mechanism of the pneumatic type, which is simple, reliable in operation and inexpensive to manufacture.

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 detailed description of several embodiments thereof when read in conjunction with the accompanying drawings, in which:

Figure 1 is a vertical sectional view of a circuit breaker operating mechanism embodying the features of the invention, the mechanism being shown in the closed position by the full lines;

Fig. 2 is a fragmentary sectional view, taken substantially along the line IlI--II of Fig. 1, show-- ing the exhaust valve of the mechanism, which cannot be seen in the section of Fig. 1;

Fig. 3 is a wiring diagram of the circuits for controlling opening and closing of the circuit breaker, the operating mechanism and circuit breaker being illustrated schematically in this figure; and

Fig. 4 is a fragmentary sectional View similar to Fig. 2 but illustrating a modified construction of the exhaust valve.

Referring to the drawings, the circuit breaker 1 shown schematically in Fig. 3, may be of any conventional construction either of the oil break, air break or gas blast type. The circuit breaker, as shown, comprises stationary contact means 9 and cooperating movable contact means H for controlling a main circuit represented diagrammatically by a single line |3. Although illustrated as a single pole circuit breaker, it will, of course, be understood that the breaker may be a multipole circuit breaker having a set of contact means 9| for each pole thereof with the movable contact means mechanically connected for simultaneous operation in the usual manner. The circuit breaker is biased to open circuit position by means of an accelerating spring shown schematically at l5, and the breaker is mechanically connected to the operating mechanism indicated generally at l1 by suitable connecting means. The connecting means is represented schematically as comprising a lever 9 pivoted at 2| on a fixed support, one end of the lever being pivotally connected to the breaker lift rod 23 and the other end being pivotally connected to the breaker operating rod 25 which is, in turn, mechanically connected to the operating mechanism l1.

Referring now to Fig. 1, the operating mechanism comprises a main casting 21 which is formed to provide a cylinder 29 closed at the upper end by an integral part of the casting. A closure member 3| is secured to the lower end of the cylinder 29 to close this end of the cylinder, and this closure member has a relatively large port 33 therein which is open to the atmosphere. An operating or latching lever 35 is pivotally mounted at one end on the casting 21. The operating lever consists of two spaced parallel levers 31 (only one being visible in Fig. l) which are pivotally connected at one end by means of a pivot pin 39 to the upper end of a pair of parallel links 4| (only one appearing in Fig. 1) which are in turn pivotally mounted on an car 43 of the main casting 21 by means of a pivot pin 44. The opposite end of the levers 31 comprising the operating lever 35 are connected by a cross member and carry a short shaft 45 therebetween, on which is rotatably mounted a roller 41 disposed between the parallel levers 31. The breaker operating rod 25 is pivotally connected by a pivot pin 49 to an intermediate point of the operating lever 35, the pivot pin 49 extending transversely through the parallel levers 31 and engaging an opening in the lower end of the rod 25 which is disposed between the parallel levers. The breaker operating lever 35 is adapted to be held in the closed position, shown in Fig. 1, to hold the breaker closed, by means of a high speed latching mechanism comprising a main latch 5| which is pivoted on the main casting 21 by means of a pivot pin 53. The latch 5| is adapted to extend between the parallel levers 31 and its latch end is adapted to engage and restrain the roller 41 carried by the free end of the breaker operating lever 35. The latch 5| is biased to latching position against a stop 55 by means of a spring pressed plunger 51 which engages a projection 59 of the latch. The plunger 51 is slidably mounted in an opening in a portion of the main casting 21 and is biased inwardly against the projection 59 of the latch 5| by means of a compression spring 5| surrounding the plunger 51 and disposed between the head thereof and a plate 63 secured to the casting 21. An adjustable nut 65 is threaded on the outer end of the spring pressed plunger 51 and this nut serves to limit inward movement or the plunger.

The construction of the latch face of the main latch 5| is such that this latch alone will not serve by itself to hold the breaker operating lever 35 in closed position unless the main latch is itself held in latching position. An auxiliary latch 61 is provided for normally engaging and holding the main latch 5| in latching position. The auxiliary latch 61 is pivoted on the casting 21 by means of a pivot pin 69 and has a latch projection 1| which is adapted to engage under a tail projection 13 of the main latch 5| in the latching position of the latching means. The auxiliary latch 61 is biased to latching position, as shown in Fig. 1, by a compression spring 15 which is seated in a recess in the casting 21 and engages an integral projection of the auxiliary latch. The auxiliary latch 61 is also provided with a projection 11 which extends directly over the upper end of the trip plunger 19 of an electromagnetic trip device 8|. The trip device 8| comprises in addition to the trip plunger 19, an E-shaped core 83 of magnetic material, an energizing winding 85 which is mounted on the center leg of the E.- shaped core, and a movable armature E1 cooperating with the core 83. The trip plunger 19 is secured to the center portion of the armature 81 and slidably extends upwardly through a guide opening in the center portion of the core 83 and through an opening in the horizontal portion of the main casting 21. The armature 81 is biased downwardly to unattracted position, as shown in Fig. 1, by a compression spring 89 which encircles the upper portion of the plunger 19 and is disposed between a collar 9| secured to the plunger and a bushing 93 which is threaded in the upper end of the opening of the casting through which the plunger extends. When the trip device 8| is energized, the armature 81 thereof is moved upwardly against the core 83 causing upward movement of the trip plunger 19. This upward movement of the trip plunger causes the auxiliary latch 1| to be rotated counterclockwise and disengage the projection 13 of the main latch 5|, whereupon the accelerating spring l5 of the circuit breaker moves the breaker to open circuit position, the operating lever 35 being rotated counterclockwise about its pivoted end by the opening movement of the breaker. During the initial opening movement of the operating lever 35, the roller 41 forces the main latch 5| in a counterclockwise direction as it clears the latch. In order to prevent the auxiliary latch from being returned to latching position until the breaker operating lever 35 is returned to closed position there is provided a U-shaped holding lever 95 the legs of which are pivotally mounted on the ends of the pivot pin 69 on opposite sides of the auxiliary latch til. The holding lever 95 is biased in a counterclockwise direction by the compression spring 91 which is seated in a recess in the casting 21 and engages a projection $9 of the holding lever. A cross member ml of the holding lever 95 is disposed directly beneath the end of the operating lever 35 so as to be held in inoperative position when the operating lever 35 is in closed position. However, when the operating lever is released and moves toward open position, the holding lever 95 is rotated in a counterclockwise direction and a lateral extension I09: of the portion 99 of the holding lever engages and holds the auxiliary latch 61 in unlatched position until the breaker operating lever 35 is returned to closed position and its roller has become reengaged by the latch face of the main latch 5i. For this purpose the biasing spring 91 of the holding lever is of greater strength than the auxiliary latch biasing spring I5.

An operating piston ")3 having piston rings N35 is movable within the operating cylinder 29 and this piston has a piston rod Ill! which slidably extends in a fluid tight manner through an opening provided therefor in the top wall of the cylinder 29. The upper end of the piston rod Iiil has a connecting element H39 threadedly connected thereto, which is pivotally connected to the pivot pin 49 carried by the operating or latching lever 35. Thus the operating piston I93 is mechanically connected directly to the circuit breaker operating rod 25. The purpose of the lever 35 is to provide a mechanical advantage for the latching means to reduce the latch load, otherwise the lever 35 could be omitted and the latch arranged to latch directly on the operating rod. The operating piston IE3 is adapted to be moved downwardly in the cylinder 29 to close or automatically reclose the circuit breaker, by compressed air from an auxiliary air reservoir or tank HI, the compressed air being admitted to the upper end of the operating cylinder 29 through an inlet passage controlled by a main inlet valve indicated generally at I 3. The opening operation of the main inlet valve is, in turn, controlled by a pilot valve H5 operated by an electromagnet ill.

A skirt on the lower end of the operating piston I03 cooperates with an annular recess I 84 formed by the closure plate 3: to provide a dash pot action to help in, stopping the piston at the end of its downward or closing stroke.

The main inlet valve [l3 comprises av valve housing I59 which is secured to the side of the main cylinder casting 27 by a plurality of bolts (not shown), and this valve housing is provided with inlet passages I2 l and the former communicating with the auxiliary air reservoir Hi and the latter communicating with an inlet port I25 in the upper end of the main cylinder 25. A main valve element 52! disposed in the valve housing has a stem I25 slidably mounted in guide sleeve '53.! which is carried by a bushing I33. The bushing I33 is threaded in an opening in the valve housing between the passages 12! and 823, and this bushing serves as a valve seat fer the valve element M27. The guide sleeve I35 is connected to the bushing :33 by a plurality of. spider legs which permit the compressed air to flow through the passages iZI and when the valve is open. The valve element 522: is biased to closed position, as shown in Fig. 1, by means of a helical compression spring I 351- which surrounds the guide sleeve I 3|. The lower end of the valve biasing spring I35 bears against the spider legs of the bushing I33 and the upper end of the spring bears against a, spring support I3! which is secured to the upper end of the valve stem I29. The auxiliary air tank III is secured to the underside of the valve housing II9 by means of a plurality of bolts I39 (only one being shown) which extend through the valve housing i it and engage an annular flange MI formed on the. neck of the air tank III, thereby clamping the flange tightly against the underside of the valve housing H9. A sealing ring 543 is inter posed between the valve housing and the flange MI of the auxiliary air tank iII to tightly seal the joint there-between. The auxiliary air tank i H is connected to a main air storage tank (not shown) by moans of a conduit M5, compressed air being supplied to and maintained in the main storage tank by a suitable motor driven compressor unit, not shown.

The main inlet valve I21 is adapted to be opened by means of a valve piston I4! to admit compressed air into the upper end of the operating cylinder 2% to close or automatically reclose the circuit breaker. The valve piston I4! is movable in a valve cylinder M9 formed in the valve housing H9, and the valve piston is biased upwardly to an. inoperative position against the head of the valve cylinder by means of a helical compression spring I5I which surrounds a portion of a valve biasing pring and is disposed between the underside of the valve piston and a shoulder formed in the valve housing I IS.

The valve operating piston M1 is adapted to be moved downwardly to open the main inlet valve, by compressed air from the auxiliary air tank Ill, through passages I52 and E53 formed in the valve housing II 9, the valve piston I l! being suitably recessed at its upper end, as shown in Fig. 1, for the purpose of permitting the compressed air to move the piston downwardly from its upper inoperative. position. The air passages and I53 communicate with cooperating passages in the pilot valve housin I55 which is secured to the main valve housing H9. Communication between. the auxiliary air tank and the upper end of the valve cylinder I is normally shut ofi, however, by a pilot valve I51 disposed in the pilot valve housing 555. The pilot valve I5! is biased to closed position against its seat by a compression spring I59 which bears against the underside of the pilot valve. The pilot valve is adapted to be operated to open position to cause air pressure to open the main inlet valve, by means of the electromagnet I I! upon energization thereof.

The cylinder portion I49 of the main inlet valve housing is provided with a plurality of ports lid (only one being shown) adjacent the lower end of the cylinder 549 which open to the atmosphere. These ports function to prevent the main inlet valve from being reclosed by the differential pressure on the under side of the valve piston I41 aided by the force of the springs I35 and I5!, as the main inlet valve 22.! opens. A skirt on the lower end of the valve piston M! closes the ports I555 as the piston I4! reaches the bottom end of its stroke to prevent any further leakage of the closing air pressure through ports 59. The ports E also function to slowly exhaust the air pressure in the operating cylinder 23 after the completion of a normal closing operation.

The electromagnet II! comprises a frame I6! and a core I53 both of magnetic material, an

energizing winding I65, and a pivoted armature I51. The electromagnet is secured to the pilot valve housing I55 by the lower end of the core I63 being threaded into an opening in the upper end of the ilot valve housing I55, thus clamping the winding spool and the frame IISI to the pilot Valve housing I55, the upper end of the core I63 having a shoulder which bears against a plate I59 which rests on the upper end of the winding spool. The armature I51 of the electromagnet is pivotally supported on the upper end of the frame IBI, and this armature engages a plunger I1I which extends slidably through an opening in the center of the core I33, and the plunger is connected at its lower end to the pilot valve I51. The pilot valve biasing spring I59 normally maintains the pilot valve in closed position and the armature I61 in unattracted position. A casing I13 is secured to the plate I59 and frame I6I, and this casing encloses the armature I61.

When the electromagnet H1 is energized, the armature I61 thereof is moved to attracted position depressing the plunger Ill and thereby causing opening of the pilot valve I51 to admit compressed air from the air tank II I to the upper end of the valve cylinder I49. The compressed air flowing into the upper end of the valve cylinder through the passages I52 and I53 forces the valve piston I41 downwardly, thereby causing opening of the main inlet valve I21 to admit compressed air to the upper end of the breaker operating cylinder 29. When the main inlet valve I21 is open, compressed air flows from the auxiliary air tank III, through the passages I2I and I23 into the main operating cylinder 29 and quickly moves the operating piston I93 downwardly to closed position, thereby closing the circuit breaker 1. As soon as the electromagnet II1 is deenergized, the pilot valve I 51 immediately closes and the main inlet valve I21 is quickly returned by its biasing spring I35 to closed position, the valve operating piston I41 being also returned upwardly to its upper inoperative position by the spring I5I.

A push button I extends through the casing I13 of the electromagnet and engages the armature I61. The push button I15 serves as a means for manually opening the pilot valve I51 to cause a closing operation of the circuit breaker. The electromagnet I I1 of the pilot valve I I5 is adapted to be operated electrically to cause closing or automatic reclosing of the circuit breaker by circuit means which will be hereinafter described.

In order to provide for quick reversal of move ment of the operating piston I93 and circuit breaker 1 (Fig. 3) to provide the effect of trip free operation of the circuit breaker and to also provide for quick reclosing of the breaker, the operating cylinder 29 is provided with an air pressure exhaust means for causing quick collapse of air pressure in the cylinder 29 whenever the tripping device BI is operated, the exhaust passage of the exhaust means being so located that it is closed by the main operating piston before the piston reaches a position at which compressed air is admitted for quick reclosure. The pressure exhaust means comprises exhaust ports I8I formed in the side wall of the operating cylinder, indicated by the dotted lines of Fig. 1.

Referring to Fig. 2, the exhaust ports I8I in the side of the main operating cylinder 29 communicate withv an exhaust passage I83 formed in the valve housing I35 of a main exhaust valve indicated generally at I81 (Fig. 2), The main exhaust valve housing I85 is secured to the side of the operating cylinder 29 by a plurality of bolts (not shown), and the exhaust passage I83 extends through the valve housing and is open to the atmosphere at a port I88 on one side of the valve housing I85. The exhaust passage I83, however, is normally closed by a piston type exhaust valve I39 which is slidably mounted in a cylinder I9I formed in the exhaust valve housing I85. The piston type exhaust valve I89 is biased upwardly to closed position in which it closes the exhaust passage I83, by means of a helical compression spring I93 disposed within the valve cylinder. The upper end of the biasing spring I93 bears against the underside of the top of the piston valve I89 and the lower end of the spring bears against the bottom closure plate I55 01 the valve cylinder I9I, An annular guide projection I91 is formed integral with the bottom end plate I95 of the valve cylinder I9I and a cooperating cylindrical shaped projection I99 is formed on the inside of the piston I89. The projections I91 and 199 serve as a guide for the biasing spring I93, and when the exhaust valve is moved downwardly to open position, the cylindrical projection I99 slides into the annular projection I31 to provide a cushioning effect by the trapped air in the bottom of the annular projection I31 at the end of the opening movement of the exhaust valve I89. The exhaust ports I8I and exhaust passage I83 are of a size sufficient when the exhaust valve is open to cause quick collapse of air pressure in the main operating cylinder 29 even though the main inlet valve I21 may be open. The exhaust passage and exhaust valve operate to quickly dump the air pressure in the main operating cylinder 29 whenever the trip device BI is operated, thus preventing any air pressure on the closing side of the main operating piston Hi3 from retarding opening movement of the circuit breaker when the circuit breaker is called upon to open. Opening of the main exhaust valve IE9 is controlled by a pilot valve, indicated generally at ZBI, which is adapted to be operated by the trip device 8I, Actual opening movement of the main exhaust valve I89 is produced by air pressure from the main operating cylinder 29, when the pilot valve is opened by the operation of the trip device 8|.

The exhaust pilot valve comprises a light pilot valve element 293 movable in an opening 294 provided therefor in the pilot valve housing 205 which is formed integral with the main operating cylinder casting 21. If desired the pilot valve housing 295 may be made as a separate casting secured to the cylinder 29. The pilot valve element 293 is directly mechanically connected to the lower end of the trip plunger 19 which is connected to and extends through the armature B1 of the trip device. An air passage 291 formed in the cylinder casting 21 communicates with the main operating cylinder at one end and at the other end with the valve opening 204, in which the pilot valve element 293 slides, The valve opening 294 is in communication with a passage.

2II (Fig. 2) formed in a closure plate 2I2 which is secured to the bottom of the pilot valve housing 295. A conduit 2I3 (Fig, 2) connects the air passage 2II to a recess 2I5 in the upper end of the exhaust valve cylinder I9l above the piston type main exhaust valve I89. The top of the main exhaust valve I89 is recessed, as shown in Fig. 2, to permit the air pressure admitted through the conduit 2I3 when the pilot valve is opened, to initiate opening movement of the main exhaust valve I89. As soon as the main exhaust valve I89 is opened a small distance by air pressure through the conduit 2I3, the air pressure flowing from the main operating cylinder 29, through the exhaust passage I83 passes over the top of the main exhaust valve I89 and the pressure quickly forces the main exhaust valve downwardly to open position and maintains it in open position against the force of the main exhaust valve spring I93 until the pressure in the main operating cylinder 29 has collapsed to a predetermined value whereupon the spring I93 immediately recloses the main exhaust valve. The air trapped in the annular projection I9'I by the piston type projection I99 assists the spring I93 in quickly returning the main exhaust valve to closed position upon collapse of pressure in the breaker operating cylinder. The biasing spring 39 of the trip plunger 19 serves to return the exhaust pilot valve 293 to closed position as soon as the trip device BI is deenergized.

A port H9 is provided in the lower end of the exhaust valve cylinder I9I to permit opening of the piston type main exhaust valve I89, the port 2I9 being opened to the atmosphere to allow air beneath the piston I99 to escape upon downward movement of the piston of the valve One or more small bleeder openings 22I are provided in the top of the piston type main exhaust valve I89 to prevent leakage air from the pilot valve 29I and from the main cylinder 29 from falsely operating the exhaust valve I89.

The exhaust ports I8! are located in the side wall of the cylinder 29 at a point intermediate the end positions of the operating piston H33 so that these exhaust ports will be closed by the main operating piston I03 after the breaker has opened a predetermined distance sufiicient to interrupt the circuit and before the main operating piston reaches the position at which compressed air is admitted for quick automatic reclosing of the breaker. This arrangement prevents the dumping of the quick reclosing air pressure and also allows a time interval for the mechanical closing of the main exhaust valve 99 on a quick reclosing operation of the mechanism. The closing of the exhaust ports I8I by the piston I93 also acts to provide a cushioning action for the partial opening stroke of the breaker and piston during a quick reclosing operation. It

will thus be seen that the pressure exhaust means in addition to providing trip free action to permit quick reversal of switching movement during closing or reclosing and substantially unretarded opening movement of the breaker, also provides for quick reversal of the opening movement during a quick reclosing operation by preventing the dumping of the reclosing air during the initial portion of the reclosing operation, before the exhaust valve I91 closes.

A pair of auxiliary switch devices 225 and 22'! is mounted on a bracket 229 secured to the main casting 27. Each of these auxiliary switch devices comprises a multi-pole auxiliary switch of conventional construction, wherein the individual switch poles are adjustable relative to their operating shafts 23I and 233, respectively, where by the auxiliary switches may be set to operate at predetermined desired points in the operation of the main circuit breaker I. The operating shaft 23! of the auxiliary switch device 225 is connected by a crank 235 and link 231 to the projection 239 of an auxiliary switch operating lever MI. The lever 24I is pivotally mounted on the fixed pivot pin 53 and the free end of this lever is connected by a slot 249 to the pivot pin 49 which connects the circuit breaker operating rod 25 to the operating lever 55. The operating shaft 233 of the auxiliary switch device is also connected by a crank 245 and a link 25? to the pro jection 239 of the auxiliary switch operating lever 2 Thus each of the auxiliary switch devices 225 and 22? is operated by and in accordance with the movement of the circuit breaker '5'.

Referring now to Fig 3 which diagrammatically shows the circuits for electrically controlling the inlet valve electromagnet II? and the trip device 8!. 25I and 253 designate a pair of supply conductors connected to a source of electric energy (not shown). The winding I65 of the electromagnet Ill which controls the admission of compressed air to the operating cylinder for closing the circuit breaker, is connected in an energizing circuit 255 extending from the supply conductor 25I, through the Winding I55, through back contacts 251 of a release relay 259 and front contacts 26! of an operating relay 293 to the supply conductor 253. The energizing winding of the operating relay 263 is connected in an energizing circuit which extends from the supply conductor 253, through a conductor 295, back contacts 26'! of the release relay 259, energizing winding of the operating relay 259, conductor 259 and through a manual control switch 2' for controlling normal closing operation of the circuit breaker, to the supply conductor 25L The energizing winding of the release relay 259 is connected in an energizing circuit which extends from the supply conductor 253, through an auxiliary switch 213 which is adapted to be closed when the circuit breaker reaches closed position, through a conductor 215, energizing winding of the release relay 259, conductor 21?. through the front contacts 2'58 of the operating relay 253 and through a conductor 219 to the supply conductor 25I.

A stick circuit is provided for maintaining the operating relay 253 energized after a momentary operation of the manual closing control switch 2. This stick circuit extends from the supply conductor 253, through the conductor 255 and back contacts 267 of the release relay 259, energiZing winding of the operating relay 253, and through a conductor 283, conductor 27?, front contacts 218 of the operating relay and conductor 279 to the supply conductor 25!. A locking circuit is also provided for maintaining the release relay 259 energized until the manual closing control switch 2' has been opened. This locking circuit for the relay 259 extends from the supply conductor 253, through a portion of the conductor 265, front contacts 285 of the release relay 259, energizing winding of release relay 259, conductor 283, conductor 299 and the manual closing control switch 2' to the supply conductor 25 I.

The winding of the trip device BI is connected in an energizing circuit which extends from the supply conductor 253, through conductor 287, through an auxiliary switch 299 which is closed when the circuit breaker is closed, conductor 29I, energizing winding of the trip device 8i, conductor 293 and the contacts 295 of a fault responsive relay 29? and through a conductor 299 to the opposite supply conductor 25L The fault responsive relay 291 is arranged to be operated to close its contacts 295 upon the occurrence of a predetermined overload, such, for example, as a short circuit in the main circuit I3 controlled by the circuit breaker I. For this purpose, the energizing winding of the protective relay 291 is arranged to be energized by a current transformer 39! associated with the main circuit conductor !3. Thus when a predetermined overload condition or short circuit ocours in the main circuit !3 controlled by the breaker I, the fault responsive relay 291 becomes energized a suflicient amount to close its contacts, thereby effecting energization of the trip device 8!. When the trip device 8! is energized, it causes release of the latching means 5!, 1! and circuit breaker operating lever 35, whereupon the circuit breaker is quickly moved to open position by its biasing springs.

The circuit breaker 1 may also be tripped open manually by means of a manually operable trip control switch 303 connected in series with a conductor 395 which is arranged to shunt the contacts 295 of the protective relay 291.

The circuit breaker 1 is adapted to be automatically reclosed immediately following interruption of the circuit by the circuit breaker 1, through the agency of a reclosing relay 391. Automatic reclosing movement of the circuit breaker is preferably initiated immediately after the circuit breaker has interrupted the circuit and before the circuit breaker reaches full open position. Reclosing relay 391 has its contacts 309 connected in series with a conductor 3!! which is connected in shunt relation to the contacts f the manual closing control switch 21!. A manually operable switch 3i3 is provided in the conductor 3!! for the purpose of preventing quick automatic reclosing operation of the circuit breaker if automatic reclosing is not desired. The energizing winding of th reclosing relay 301 is connected in series in an energizing circuit 3!5 which extends from the supply conductor 253, through the winding of the reclosing relay 301, through an adjustable auxiliary switch 3l1 which is adjusted to close during the initial opening movement of the circuit breaker, and through contacts 3!9 of the protective relay 291 and conductor 299 to the opposite supply conductor 25!.

The operation of the mechanism is as follows, assuming the circuit breaker to be in closed position, as shown in Figs. 1 and 3. When a predetermined overload or short circuit occurs in the main circuit !3 controlled by the circuit breaker 1, the fault responsive relay 291 is immediately energized and closes its contacts 295 to efiect energization of the trip device 8 I. When the trip device 8! is thus energized, it moves the trip plunger 19 upwardly to cause the auxiliary latch 61 to release the main latch thereby releasing the breaker operating lever 35. The circuit breaker is immediately moved to open position by its biasing spring !5. The operation of the trip plunger 19 also opens the pilot valve 293, thereby causing the main exhaust valve to be opened and quickly exhaust any air pressure in the operating cylinder 29, if there is any pressure in the cylinder 29 at this time. The main circuit I3 is interrupted during the first part of the opening movement of the circuit breaker 1 by the time the circuit breaker has opened through only a part of its full open distance.

Assuming the manual switch 3l3 to be closed, quick automatic reclosing operation of the circuit breaker will be caused to take place as soon as the circuit breaker has opened through a predetermined distance, less than the full open distance, Quick automatic reclosing operation of the circuit is accomplished by the reclosing relay 301 in response to closing of its circuit by the contacts 3l9 of the fault responsive relay 291 and closing the adjustable auxiliary switch 3l1. The contacts 3!9 of the fault responsive relay are closed simultaneously with the contacts 295 upon operation of the fault responsive relay in response to an overload or short circuit, thus immediately preparing the energizing circuit for the reclosing relay 391. During the initial opening movement of the circuit breaker, the aux--v iliary switch 3!1 closes and completes the energizing circuit for the reclosing relay 391', and the relay 391 thereupon closes its contacts 399, completing an energizing circuit for the operating relay 263, this energizing circuit extending from the supply conductor 25!, through the contacts 399 of the reclosing relay, conductor 3!!, conductor 269, energizing winding of operating relay 263, back contacts 261 of the release relay 259, and conductor 265 to the opposite supply conductor 253. The operating relay instantly closes its contacts 218 and 23!. Closing of the operating relay contacts 26! completes an nergizing circuit for the inlet valve controlling electromagnet l!1, through the back contacts 251 of the release relay, and through conductor 255. The electromagnet I !1 when energized opens the pilot valve !51, thereby causing opening of the main inlet valve !21. Compressed air is thereupon admitted to the upper end of the operating cylinder 29 quickly moving the operating piston ma downwardly to close the circuit breaker. These operations occur substantially instantaneously so that reclosing movement of the operating piston is initiated immediately after the circuit has been interrupted and before the breaker reaches the full open position. The position at which automatic reclosing movement of the main operating piston I93 takes place is indicated by the dotted lines R in Fig. 1. As has previously been explained, the exhaust ports !8! are located in a position such that they are closed by the operating piston I03 during the first part of the opening movement of the breaker before the piston reaches the position at which compressed air is admitted for quick reclosure, so that dumping of the reclosing air is thereby prevented and the exhaust valve [89 is given a time interval to mechanically close before the downward movement of the operating piston opens the exhaust ports !8!.

Closing of the contacts 218 of the operating relay 263 prepares an energizing circuit for the release relay 259. This circuit extending from the supply conductor 25!, through conductor 219, contacts 218, conductor 211, energizing winding of the release relay 259, conductor 215 to the auxiliary switch 213 which closes the instant the circuit breaker reaches closed position. As soon as the circuit breaker reaches closed position, the auxiliary switch 213 completes the energizing circuit for the release relay 259, whereupon the release relay operates to open its back contacts 261 and 251 and closes its front contacts 285. The opening of contacts 251 effects deenergization of the inlet valve controlling electromagnet !!1, thereby causing shutting off the supply of compressed air to the operating cylinder 29, and the opening of contacts 231 efiects deenergization of the operating relay 263. The closing of the front contacts 285 normally produces no effect during quick automatic reclosing operation, since the contacts 399 of the reclosing relay open before the breaker reaches closed position.

If the condition which caused the overload or short circuit has been removed by the time the circuit breaker completes the circuit upon a quick automatic reclosing operation, the circuit breaker remains closed and the control circuits assume the normal condition shown in Fig. 3. However, if the fault condition which causes the overload or short circuit is still present at the time the circuit is completed by the contacts of the circuit breaker during a quick reclosing operation thereof, the fault responsive relay 23! is again energized the instant the main circuit is completed again causing energization of the trip device 8!. Consequently trip plunger 19 is again operated. upwardly opening the pilot valve 203, thereby causing the air pressure in the operating cylinder 29 to open the main exhaust valve I89 and quickly cause collapse of the air pressure in the operating cylinder 29 even though the main inlet valve !2'! may still be open at this time. The trip device 8| also moves the latches to released position. Thus the circuit breaker is caused to quickly reverse its movement and start opening even though the inlet valve may be open at this time. The opening movement of the circuit breaker is substantially unretarded due to the quick collapse of air pressure in the operating cylinder 29. A lockout device 32! of any conventional construction may be provided in the circuit of the reclosing relay 3!]? to prevent more than one quick automatic reclosing operation of the circuit breaker, or to open the quick reclosing circuit and transfer control of the reclosing relay to a time delayed reclosing device in a manner well known in the art. If the lockout device 32! is of a character to provide for only a single quick automatic reclosure of the circuit breaker, the circuit breaker proceeds to the full open position and remains open after one unsuccessful attempt at quick reclosure.

Normal closing operation of the circuit breaker from the full open position is accomplished by closing the manual control switch 21!. The closing of this switch completes an energizing circuit for the operating relay 263. When the operating relay is thus energized, it closes its contacts 26! and 218, the closing of contacts 26! completing an energizing circuit for the inlet valve controlling electromagnet H1, thereby causing compressed air to be admitted to the operating cylinder to close the circuit breaker. The contacts 218 prepare an energizing circuit for the release relay 259, this circuit being completed by the auxiliary switch 213 when the breaker reaches the fully closed position. The manual closing control switch 21! need only be closed for an instant because as soon as the operating relay closes its contacts 218, a stick circuit is completed for maintaining the operating relay energized until the release relay operates. This stick circuit has been previously described. Closing of the contacts 218 of the operating relay 263 prepares an energizing circuit for the release relay 259 which is completed by the auxiliary switch 213 when the breaker reaches the fully closed position. When the release relay 259 is energized, it opens its back contacts 25! and 261, thereby deenergizing the inlet valve controlling electromagnet I !'l by the contacts 25! and also deenergizing the operating relay 263 by the contacts 26! nd .preventing further energization of the operating relay as long as these contacts remain open. The operation of the release relay also closes its front contacts 285 to complete a locking circuit for maintaining the release relay energized as long as the manual closing control switch 21! is held closed, this locking circuit extending from the supply conductor 253, through the front contacts 285 and energizing winding of the release relay 259, conductor 283, conductor 269 and manual closing control switch 21! to the supply conductor 25 I. This locking circuit thus prevents the circuit breaker from pumping if the breaker will not remain closed and the manual control switch is held in closed position. If the circuit breaker should be closed against an overload or short circuit during a normal closing operation, the trip device 8! will be operated to release the latch and cause opening of the exhaust valve !81 so that the breaker will immediately open even though the inlet valve I89 may be opened at the time the circuit is completed.

The circuit breaker may be manually tripped open by closing the manual trip control switch 303 which effects energization of the trip device 8! and tripping of the circuit breaker.

A modification of the main exhaust valve is illustrated in Fig. a. The construction of thi modified form of the exhaust valve is substantially the same as that shown in the original embodiment, except that the valve cylinder is open at its lower end and the lower end of the valve biasing spring is mechanically connected to the auxiliary switch operating lever 24%. Referring to Fig. 4, the modified exhaust valve comprises a valve housing 325 secured to the side of the main operating cylinder 29. The valve housing is formed to provide a valve cylinder 32? which is open at it lower end, and the housing contains the exhaust passage 329 which is open to the atmosphere at one end and communicates at its other end with the exhaust ports Hit of the operating cylinder 29. The exhaust valve 33! is a piston type valve which i slidably mounted in the valve cylinder 32?. The valve 33! is biased upwardly to closed position to close the exhaust passage 329 by means of a helical biasing spring the upper end of which bears against the underside of the piston type exhaust valve. The lower end of the spring 333 bears against a spring support 335 which is carried by a connecting rod 33?. The connecting rod 331 slidably extends through openings provided in the valve 33! and valve housing 325, and the upper end of the connecting rod is pivotally connected at 338 to the auxiliary switch operating lever 26!. The upper end of the valve cylinder 32'! has a passage 2I5 which is connected by conduit 2!? to the pilot valve passage 2! l in the same manner as shown and described in connection with the original embodiment, and the upper end of the piston type valve 33! is provided with a recess so that compressed air admitted through the conduit 2!3 to the upper end of the cylinder can initiate opening of the exhaust valve 33!. The purpose of connecting the lower end of the valve biasing spring to the auxiliary switch operating lever 24! is to provide for additional compression of the spring as the circuit breaker operating mechanism opens in order to insure quick closing of the exhaust valve and to prevent the valve from sticking open after the air in the breaker operating cylinder has been exhausted. The remaining structure of the exhaust valve and its function is substantially the same as in the case of the original embodiment.

While the invention has been disclosed in accordance with the provision of th patent statutes, it is to be understood that various changes in the structural details and arrangements of parts thereof may be made without departing from some of the essential features of the invention.

We claim as our invention:

1. In combination, a circuit breaker biased to open circuit position, operating mechanism therefor comprising an operating cylinder, a piston in said cylinder operatively related to the breaker, a source of compressed air for operating said piston to close the breaker, means including an inlet valve operable to connect said source of compressed air to said cylinder to close the breaker, latching means for releasably holding said breaker closed, trippin means operable in response to predetermined abnormal conditions in the circuit to cause said latching means to release the breaker and thereby cause opening of the breaker, air pressure exhaust means connected to said cylinder intermediate its ends so as to be closed off by said piston when in an intermediate position, said exhaust mean including a normally closed exhaust valve directly connected to said cylinder apart from the connection to said source of compressed. air, said valve when opened causing quick collapse of pressure in said cylinder except when said piston is at or to one side of said intermediate position, and means operated by said tripping means upon operation thereof for causing opening of said exhaust valve.

2. In combination, a circuit breaker biased to open circuit position, operating mechanism therefor comprising an operating cylinder, a piston in said cylinder operatively related to the breaker, a source of compressed air for operating said piston to close the breaker, means including an inlet valve operable to connect said source of compressed air to said cylinder to close the breaker, latching means for releasably holding said breaker closed, a tripping electromagnet having an armature operable upon the occurrence of predetermined abnormal conditions in the circuit to cause said latching means to release said breaker and thereby caus opening of the breaker, air pressure exhaust means associated with said operating cylinder including an exhaust valve biased closed and having a piston Operable by air pressure to open said valve, said exhaust valve when opened causing quick collapse of pressure in said breaker operating cylinder, and means including a normally closed pilot valve operable by the armature of said tripping electromagnet upon operation thereof to cause opening of said exhaust valve.

3. An operating mechanism for a circuit breaker comprising an operating cylinder, a piston reciprocable in said cylinder for actuating the breaker, a source of compressed air for operating said piston, an inlet valve operable to connect one end of said cylinder to said source of compressed air to close the breaker, means operable to cause opening of the breaker, an electromagnet having an armature operable in response to the occurrence of predetermined abnormal conditions to cause operation of said means to open the breaker, air pressure exhaust means associated with said operating cylinder including an exhaust valve biased closed and having a piston operable by air pressure to open said exhaust valve, said exhaust mean when said exhaust valve is open causing quick collapse of air pressure in said cylinder on the closing side of said breaker operating piston when said breaker-operating piston is in or adjacent closed position, and a normally closed pilot valve operable by the armature of said electromagnet upon operation thereof to cause opening of said exhaust valve.

4. An operating mechanism for a circuit breaker comprising an operating cylinder, at piston reciprocable in said cylinder for actuating the breaker, a source of compressed air for operating said piston, an inlet valve operable to connect one end of said cylinder to said source of compressed air to close the breaker, means operable to cause opening of the breaker, an electromagnet having an armature operable in response to the occurrence of predetermined abnormal conditions to cause operation of said means to open the breaker, an air pressure exhaust passage communicating with said operating cylinder of a size to cause quick collapse of pressure in said operating cylinder on the closing side of said piston even though said inlet valve is open, a piston type exhaust valve in said passage biased to normally close said passage, said exhaust valve being operable to open position to open said passage when air pressure is applied to one end of the piston of said valve, an auxiliary air passage connecting a portion of said operating cylinder with said one end of said piston valve, a pilot valve in said auxiliary passage biased to close said passage, said pilot valve being connected to the armature of said electromagnet to be opened thereby when said armature is operated to thereby cause opening of said exhaust valve by air pressure in said cylinder.

5. In combination, a circuit breaker biased to open circuit position, operating mechanism therefor comprising an operating cylinder, a piston in said cylinder connected to the breaker, a source of compressed air for operating said piston to close the breaker, means including an inlet valve operable to connect said source of compressed air to said cylinder to close the breaker, latching means for releasably holding said breaker closed, a tripping electromagnet having an armature operable upon the occurrence of predetermined abnormal conditions in the circuit to cause said latching means'to release the breaker and thereby cause opening of the breaker, a pressure exhaust passage communieating with said cylinder of a size to cause quick collapse of pressure in said cylinder when said passage is open, a piston type exhaust valve in said passage normally biased closed to close said passage, said exhaust valve being operable to open position when a predetermined air pressure is applied to one end of the piston of said valve, an auxiliary air passage connecting a portion of said cylinder with the exhaust valve housing adjacent said one end of the valve piston, a pilot valve in said auxiliary passage biased to normally close said passage, said pilot valve being connected to the armature of said tripping electromagnet to be opened thereby when said armature is operated to thereby cause opening of said exhaust valve by air pressure in said cylinder.

6. In combination, a circuit breaker biased to open circuit position, operating mechanism therefor comprising compressed air operated closing means for closing the breaker, latching means for releasably holding said breaker in closed circuit position, tripping means operable in response to predetermined abnormal conditions in the circuit to cause said latching means to release the breaker and thereby cause opening of the breaker, means automatically operable to initiate an instantaneous reclosing operation of the closing means after interruption of the circuit and at least by the time the breaker reaches full open position, air pressure exhaust means associated with said closing means including a normally closed exhaust valve operable to cause a quick collapse of closing air pressure in said closing means, said tripping means when operated causing opening of said exhaust valve, and means responsive to the position of said closing means for mechanically closing said exhaust means when said closing means is in the neighborhood of its open position.

7. In combination, a circuit breaker biased to open circuit position, operating mechanism therefor comprising an operating cylinder, a piston in said cylinder operatively related to said breaker, a source of compressed air, an inlet valve operable to connect said source of com pressed air to one end of said cylinder to effect closing of the breaker, latching means for releasably holding said breaker closed, tripping means operable upon the occurrence of predetermined overload conditions in the circuit to cause said latching means to release the breaker and thereby cause opening of the breaker, means operable to automatically open said inlet valve to cause said operating piston to initiate reclosing of the breaker after interruption of the circuit and before said breaker reaches the full open position, an air pressure exhaust passage communicating with said cylinder at a point intermediate its ends, said exhaust passage being of a size sufiicient to cause quick collapse of pressure in said cylinder even if said inlet valve is open when the piston is near the end of its stroke opposite the inlet end of the cylinder and said exhaust passage being closed off from the inlet when the piston is between said intermediate point and the inlet end of the cylinder sov as to permit quick reclosing of the breaker before reaching full open position, an exhaust valve in said passage biased to normally close said exhaust passage, and means operated by said tripping means upon operation thereof to cause opening of said exhaust valve.

8. In combination, a circuit breaker biased to open circuit position operating mechanism therefor comprising an operating cylinder, a piston movable in said cylinder and operatively related to said breaker, a source of compressed air, means including an inlet valve for connecting one end of said cylinder to said source of compressed-air to effect closing of the breaker, latching means for releasably holding said breaker closed, tripping means operable upon the occurrence of predetermined overload conditions in the circuit to cause said latching means to release the breaker and thereby cause opening of the breaker, a pressure exhaust passage communicating with said cylinder through the side Wall of the cylinder at a predetermined point intermediate the end positions of said piston, said passage having a size such as to cause a quick collapse of pressure in said cylinder when said passage is open even if said inlet valve is open, an exhaust valve in said passage normally biased closed to close said exhaust passage, and means operated by said tripping means upon operation thereof for causing opening of said exhaust valve.

9. In combination, a circuit breaker biased to open circuit position, operating mechanism therefor comprising an operating cylinder, a piston movable in said cylinder and operatively related to said breaker, a source of compressed air, means including an inlet valve for connecting one end of said cylinder to said source of compressed air to effect closing of the breaker, latching means for releasably holding said breaker closed, tripping means operable upon the occurrence of predetermined overload conditions in the circuit to cause said latching means to release the breaker and thereby cause opening of the breaker, a pressure exhaust passage communieating with said cylinder of a size sufficient to cause quick collapse of pressure in said cylinder when said passage is open even if said inlet valve is open, an exhaust valve in said passage biased to normally close said passage, means operated substantially simultaneously with said tripping means for causing opening of said exhaust valve, said exhaust passage being closed by a part movable in accordance with the movement of said piston when said piston is within a predetermined distance of the full open position.

10. In combination, a circuit breaker biased to open circuit position, operating mechanism therefor comprising an operating cylinder, a piston movable in said cylinder and operatively related to said breaker, a source of compressed air, means including an inlet valve for connecting one end of said cylinder to said source of compressed air to effect closing of the breaker, latching means for releasably holding said breaker closed, tripping means operable upon the occurrence of predetermined overload conditions in the circuit to cause said latching means to release the breaker and thereby cause opening of the breaker, a pressure exhaust passage communicating with said cylinder through the side wall thereof at a point intermediate the ends thereof, said passage being of a size sufficient to cause quick collapse of pressure in said cylinder when said passage is open, an exhaust valve in said passage normally biased closed, means operated by said tripping means upon operation thereof for causing opening Of said exhaust valve, said operating piston closing communication between a portion of said cylinder and said exhaust passage when the breaker is opened more than a predetermined distance to permit quick reclosing operation of the breaker and allow said exhaust valve to close during a quick reclosing operation.

11. An operating mechanism for a circuit breaker comprising an operating cylinder, a piston in said cylinder operatively related to the breaker, a source of compressed air for actuating said piston, means including an inlet valve operable to connect one end of said cylinder to said source of compressed air to effect closing of the breaker, latching means for releasably holding the breaker closed, tripping means operable upon the occurrence of predetermined overload conditions to cause said latching means to release the breaker and thereby cause opening of the breaker, a pressure exhaust passage communicating with said cylinder through the side Wall thereof, said passage being of a size sufficient when said passage is open to cause quick collapse of pressure in said cylinder even if said inlet valve is open, a piston type exhaust valve in said passage biased to normally close said passage, means operated substantially simultaneously with said tripping means for causing said exhaust valve to be opened by air pressure in said cylinder, said operating piston closing said exhaust passage off from a portion of the cylinder when said breaker has opened a predetermined amount less than the full opening distance.

12. An operating mechanism for a circuit breaker comprising an operating cylinder, a piston in said cylinder operatively related to the breaker, a source of compressed air for actuating aroma;

said piston to close the breaker, means including an inlet valve operable to connect one end of said cylinder to said source of compressed air to effect closing of the breaker, means operable to cause opening of the breaker, an electromagnet having an armature operable upon the occurrence of predetermined overload conditions in the circuit to cause operation of said means to open the breaker, a pressure exhaust passage communicating with said cylinder, said passage being of a size sufficient when said passage is open to cause quick collapse of pressure in said cylinder even if said inlet valve is open, a piston type exhaust valve in said passage, spring means for biasing said exhaust valve to normally close said passage, means operated by the armature of said electromagnet upon operation thereof to cause said exhaust valve to be opened by air pressure in said cylinder, and a connection between said spring means and a part movable with said piston for moving said spring to increase the force acting to close said exhaust valve during opening of the breaker.

13. Operating mechanism for a circuit breaker comprising an operating cylinder, a piston in said cylinder operatively related to the breaker, a source of fluid under pressure for actuating said piston, means including an inlet valve operable to connect one end of said cylinder to said source of fluid under pressure to effect closing of the breaker, means operable to cause opening of the breaker, an electromagnet having an armature operable upon the occurrence of predetermined overload conditions in the circuit to cause operation of said means to open the breaker, means automatically operable to open said inlet valve to initiate quick automatic reclosing operation of the breaker after interruption of the circuit but before the breaker reaches full open position, a fluid pressure exhaust passage communicating with said cylinder at a point intermediate the end positions of said piston, said passage being of a size suflicient when said passage is open to cause quick collapse of fluid pressure in said cylinder on the closing side of the piston even if said inlet valve is open, a piston type exhaust valve in said passage, spring means biasing said exhaust valve closed to normally close said exhaust passage, means operated simultaneously with the operation of said armature to cause said exhaust valve to be opened by fluid pressure in a portion of said cylinder, said breaker operating piston closing off communication between said exhaust passage and a portion of the operating cylinder after said breaker has opened a Y predetermined amount but before the time at which fluid under pressure is admitted to said cylinder for a quick automatic reclosing operation, thereby preventing dumping of the reclcsing fluid pressure in said cylinder during the first portion of a quick reclosing operation and allowing a time interval for mechanical closing of said exhaust valve.

14. In combination, a circuit breaker biased to open circuit position, operating mechanism therefor, comprising an operating cylinder, a piston in said cylinder operatively related to the breaker, a source of fluid under pressure for actuating said piston to close the breaker, means including an inlet valve operable to connect one end of said cylinder to said source of fluid under pressure to effect closing of the breaker, latching means for holding said breaker closed, tripping means operable upon the occurrence of predetermined overload conditions in the circuit to cause said latching means to release the breaker and thereby cause opening of the breaker, means automatically operable to open said inlet valve to initiate a quick automatic reclosing operation of the breaker after interruption of the circuit but before said breaker reaches full open position, a fluid pressure exhaust passage communieating with said cylinder at a point intermediate the end positions of said piston, said passage being of a size sufficient when said passage is open to cause quick collapse of fluid pressure in said cylinder even if said inlet valve is open, a piston type exhaust valve in said passage biased by a spring to normally close said passage, means operated by said tripping means upon operation thereof for causing said exhaust valve to be opened by fluid pressure in a portion of said cylinder, said breaker operating piston acting to close off communication between said exhaust passage and a portion of the operating cylinder after said breaker has opened a predetermined amount but before the time at which fluid under pressure is admitted to said cylinder for a quick automatic reclosing operation, thereby preventing dumping of the reclosing fluid pressure in said cylinder during the first portion of a quick reclosing operation and allowing a time interval for mechanical closing of said exhaust valve.

15. In combination, a circuit breaker biased to open circuit position, operating mechanism therefor comprising an operating cylinder, 2. piston in said cylinder operatively related to the breaker, a source of compressed air for operating said piston to close the breaker, means including an inlet valve operable to connect said source of compressed air to said cylinder to close the breaker, latching means for releasably holding said breaker closed, electromagnetic tripping means operable in response to predetermined abnormal conditions in the circuit to cause said latching means to release the breaker to thereby cause opening of the breaker, exhaust means associated with said cylinder includin a piston type exhaust valve biased closed and operable by air pressure to cause a quick collapse of pressure in said operating cylinder even if said inlet valve is open, means including a normally closed pilot valve operable to cause opening of said exhaust valve, and means for causing opening of said pilot valve substantially simultaneously with the operation of said electromagnetic tripping means. i

16. In combination, a circuit breaker, operating mechanism therefor comprising an operating cylinder, a piston in said cylinder operatively related to the breaker, a source of compressed air for operating said piston, means including an inlet valve operable to connect said source of compressed air to said cylinder to close the breaker, latching means for holding said breaker in closed position, tripping means operable in response to predetermined abnormal conditions in the circuit to cause said latching means to release the breaker, a, compressed air operated dump valve directly connected to said cylinder apart from the connection to said pressure source for instantaneously reducing back pressure against said piston so that high speed opening operation of said breaker may be obtained and means for causing opening of said dump valve in response to operation of said tripping means by pressure air from the cylinder if, and only if, there is pressure air in the cylinder.

17. A pneumatic operating mechanism of the trip-free type for an electric circuit breaker com- 21 prising a source of compressed gas, a fluid motor including a piston and cylinder, an inlet to said cylinder from said source, a control valve between said source and inlet, said valve being arranged to admit gas under pressure from said source to said cylinder, means operatively relating said piston to said circuit breaker for closing said breaker, a dump valve connected to said cylinder intermediate its ends for venting rapidly said cylinder to atmosphere at the work ing face of said piston only when said piston is on the side of said dump valve connection opposite said inlet whereby said piston can then return toward its initial position notwithstanding flow of fluid under pressure from said source through said control valve and inlet to said cylinder, and means for causing opening movement of said breaker and for also opening said dump valve for causing trip-free operation.

JAMES M. CUMMING. RICHARD C. CUNNINGHAM.